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  • Pihlajoki, Marjut (Helsingin yliopisto, 2014)
    The main steroidogenic organs, adrenal cortex and ovary, arise from a common pool of progenitors in the developing embryo. Similar signaling pathways regulate the differentiation, growth, and survival of cells in these tissues. Proper development of the adrenal cortex and ovary requires precise spatiotemporal control of gene expression and apoptosis; disruption of these processes may lead to congenital disorders or malignant transformation. Earlier in vitro studies demonstrated that transcription factor GATA6 regulates the expression of multiple steroidogenic genes in the adrenal cortex. To show that GATA6 is a crucial regulator of adrenocortical development and function in vivo, we generated a mouse model in which Gata6 is conditionally deleted in steroidogenic cells. These mice exhibited a complex adrenal phenotype that includes cortical thinning, blunted aldosterone production, lack of an X-zone, impaired apoptosis, and subcapsular cell hyperplasia. These results offer genetic proof that GATA6 regulates the differentiation of steroidogenic progenitors into adrenocortical cells. Ovarian granulosa cell tumors (GCTs), the most common sex-cord stromal tumors in women, are thought to be caused by aberrant granulosa cell apoptosis during folliculogenesis. A somatic missense mutation in transcription factor FOXL2 (402C→G) is present in vast majority of human GCTs. FOXL2 plays a key role in the development and function of normal granulosa cells. Wild type (wt) FOXL2 induces GCT cell apoptosis, while mutated FOXL2 is less effective. To clarify the molecular pathogenesis of GCTs, we investigated the impact of FOXL2 and two other factors implicated in granulosa cell function, GATA4 and SMAD3, on gene expression and cell viability in GCTs. We found that these factors physically interact and that GATA4 and SMAD3 synergistically induce CCND2 promoter transactivation, which is reduced by both wt and mutated FOXL2. Finally, we demonstrated that GATA4 and SMAD3 protect GCT cells from wt FOXL2 induced apoptosis without affecting the apoptosis induced by mutated FOXL2. These findings suggest that mutated FOXL2 disrupts the balance between growth and apoptosis in granulosa cells, leading to malignant transformation. The treatment of recurrent or metastatic GCTs is challenging, and biologically targeted treatment modalities are needed. Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) activates the extrinsic apoptotic pathway. Interestingly, TRAIL is able to induce apoptosis in malignant cells without affecting normal cells. Vascular endothelial growth factor (VEGF) is the key regulator of both physiological and pathological angiogenesis. Cancer cells often express VEGF receptor, and an autocrine VEGF/VEGFR signaling loop exists in several types of cancer cells. We found that GCT cells express functional TRAIL and VEGF receptors, and that treatment with TRAIL and the VEGF-binding antibody (bevacizumab) induce GCT cell apoptosis. These findings establish a preclinical basis for targeting these two pathways in the GCT treatment.
  • Boldt, Robert (Helsingin yliopisto, 2014)
    Hearing is a versatile sense allowing us, among other things, to avoid danger and engage in pleasurable discussions. The ease with which we follow a conversation in a noisy environment is astonishing. Study I in this thesis used functional magnetic resonance imaging to explore the large-scale organization of speech and non-speech sound processing during a naturalistic stimulus comprised of an audio drama. Two large-scale functional networks processed the audio drama; one processed only speech, the other processed both speech and non-speech sounds. Hearing is essential for blind subjects. Anatomical and functional changes in the brains of blind people allow them to experience a detailed auditory world, compensating for the lack of vision. Therefore, comparing early-blind subjects brains to those of sighted people during naturalistic stimuli reveals fundamental differences in brain organization. In Study II, naturalistic stimuli were employed to explore whether one of the most distinguishing traits of the auditory system the left-lateralized responses to speech changes following blindness. As expected, in sighted subjects, speech processing was left-hemisphere dominant. Curiously, the left-hemisphere dominance for speech was absent or even reversed in blind subjects. In early-blind people, the senses beyond vision are strained as they try to compensate for the loss of sight; on the other hand, the occipital cortices are devoid of normal visual information flow. Interestingly, in blind people, senses other than vision recruit the occipital cortex. Additional to changes in the occipital cortex, the sensory cortices devoted to touch and hearing change. Data presented here suggested more inter-subject variability in auditory and parietal areas in blind subjects compared with sighted subjects. The study suggested that the greater the inter-subject variability of the network, the greater the experience-dependent plasticity of that network. As the prefrontal areas display large inter-subject spatial variability, the activation of the prefrontal cortex varies greatly. The variable activation might partly explain why the top-down influences of the prefrontal cortex on tactile discrimination are not well understood. In the fourth study, anatomical variability was assessed on an individual level, and transcranial magnetic stimulation was targeted at individually-chosen prefrontal locations indicated in tactile processing. Stimulation of one out of two prefrontal cortex locations impaired the subjects ability to distinguish a single tactile pulse from paired pulses. Thus, the study suggested that tactile information is regulated by functionally specialized prefrontal subareas.
  • Eriksson, Johanna (Helsingin yliopisto, 2014)
    Cutaneous melanoma is one of the most aggressive malignancies, typified by a high metastatic tendency and refractoriness to treatments. Identification of the molecular mechanisms behind the development and progression of melanomas could provide new insights into treating this challenging disease. The aim of this study was to identify and characterize genes and proteins associated with melanoma development and progression by comparing genome-wide gene expression profiles from different stages of melanoma, and to evaluate their potential as diagnostic and prognostic markers and therapeutic targets. A further aim was to develop sensitive RT-PCR and immunohistochemical assays for the detection of melanoma micrometastases. We found the outgrowth of melanoma metastases to be associated with the activation of stromal fibroblasts, increased TGFβ/Smad2 signaling, and an up-regulation of TGFβ-target genes encoding extracellular matrix proteins fibronectin, collagen-I, periostin, and versican. These proteins were found to form around tumor cells fibrillar networks, which, suggested by our functional studies, promote the growth and migration of tumor cells as well as stromal fibroblasts and endothelial cells. In addition, periostin and cellular fibronectin were found to be specifically up-regulated in newly-formed tumor blood vessels. We further found a common up-regulation of collagen triple helix repeat containing 1 (CTHRC1) and cysteine cathepsin B and L1 proteases during melanoma progression. Our analyses suggest that CTHRC1 is, together with fibronectin and integrin β3, part of the pro-invasive and pro-angiogenic transcriptional program induced by the NFATC2 (nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 2) transcription factor. Cathepsins B and L1 (and TGFβ signaling), in turn, were found to play essential roles in the co-invasive process of melanoma cells and activated fibroblasts. Further, our results suggest that high expression of CTHRC1, fibronectin, and cathepsin B in primary melanomas may serve as prognostic factors predicting poor survival. Combined, these results suggest that TGFβ receptors, fibronectin, periostin, and CTHRC1, as well as cathepsins B and L1 are attractive therapeutic targets against advanced melanomas. In addition, we identified the best gene expression markers for the detection of melanoma lymph node metastases. Of the identified genes, melan-A (MLANA), tyrosinase (TYR), melanoma inhibitory activity (MIA), preferentially expressed antigen in melanoma (PRAME), and osteopontin (SPP1) were tested as potential melanoma micrometastasis markers by RT-PCR and immunohistochemistry (IHC). Graded MLANA- and TYR-RT-PCR analyses were found to detected clinically significant metastases better than IHC, suggesting that quantifiable RT-PCR analyses should be used to confirm and complement histological and immunohistochemical examinations. Further, the melanoma-specific genes, PRAME and SPP1, may be used to differentiate melanoma cells from benign nevus cells occasionally residing in lymph nodes.
  • Marbacher, Serge (Helsingin yliopisto, 2014)
    Background and Purpose: Subarachnoid hemorrhage attributable to saccular intracranial aneurysm (IA) rupture is a devastating disease leading to stroke, permanent neurological damage and death. Despite rapid advances in the development of endovascular treatment (EVT), complete and long lasting IA occlusion remains a challenge, especially in complexly shaped and large-sized aneurysms. Intraluminal thrombus induced by EVT may recanalize. The biological mechanisms predisposing IA to recanalize and grow are not yet fully understood, and the role of mural cell loss in these processes remains unclear. To elucidate these processes, animal models featuring complex aneurysm architecture and aneurysm models with different wall conditions (such as mural cell loss) are needed. Materials and Methods: Complex bilobular, bisaccular and broad-neck venous pouch aneurysms were microsurgically formed at artificially created bifurcations of both common carotid arteries in New Zealand rabbits. Sidewall aneurysms were microsurgically created on the abdominal aorta in Wistar rats. Some sidewall aneurysms were decellularized with sodium dodecyl sulfate. Thrombosis was induced using direct injection of a fibrin polymer into the aneurysm. CM-Dil-labeled syngeneic smooth muscle cells were injected into fibrin embolized aneurysms. The procedures were followed up with two-dimensional intra-arterial digital subtraction angiography, contrast-enhanced serial magnetic resonance angiographies, endoscopy, optical projection tomography, histology and immunohistochemistry. Results: Aneurysm and parent vessel patency of large aneurysms with complex angioarchitecture was 90% at one month and 86% at one year follow-up in the bifurcation rabbit model. Perioperative and one month postoperative mortality and morbidity were 0% and 9%. Mean operation time in the rat model was less than one hour and aneurysm dimensions proved to be highly standardized. Significant growth, dilatation or rupture of the experimental aneurysms was not observed, with a high overall patency rate of 86% at three week follow-up. Combined surgery-related mortality and morbidity was 9%. Decellularized aneurysms demonstrated a heterogeneous pattern of thrombosis, thrombus recanalization and growth, with ruptures in the sidewall rat model. Aneurysms with intraluminal local cell replacement at the time of thrombosis developed better neointima, showed less recurrence or growth and no ruptures. Growing and ruptured aneurysms demonstrated marked adventitial fibrosis and inflammation, complete wall disruption and increased neutrophil accumulation in unorganized luminal thrombus. Conclusions: Creation of complex venous pouch bifurcation aneurysms in the rabbit is feasible, with low morbidity, mortality and high short-term and long-term aneurysm patency. They represent a promising approach for in vivo animal testing of novel endovascular therapies. The sidewall aneurysm rat model is a quick and consistent method to create standardized aneurysms. Aneurysms missing mural cells are incapable of organizing a luminal thrombus, leading to aneurysm recanalization and increased inflammatory reactions. These, in turn, result in severe wall degeneration, aneurysm growth and eventual rupture. The results of the presented studies suggest that the biologically active luminal thrombus drives the healing process towards destructive wall remodeling and aneurysm rupture. Local smooth muscle cell transplantation compensates for mural cell loss and reduces recurrence, growth and rupture rate in a sidewall aneurysm rat model.
  • Lilius, Tuomas (Helsingin yliopisto, 2014)
    Opioid analgesics are effective in relieving acute and chronic pain. However, adverse effects and the development of opioid dependence and tolerance may restrict the use of opioids and result in inadequate pain relief. The effects of four structurally and functionally different drugs already on the market, ibudilast, atipamezole, spironolactone, and ketamine, were studied in coadministration with morphine, the prototypical mu-opioid receptor agonist. Experiments were conducted using thermal and mechanical tests of nociception in male Sprague-Dawley rats. Morphine tolerance was produced during four days by subcutaneous or intrathecal delivery of morphine. Drug and metabolite concentrations were measured using high-pressure liquid chromatography-tandem mass spectrometry. The objective of the thesis study was to search for potential drugs to augment morphine antinociception and prevent opioid tolerance. Ibudilast, a phosphodiesterase and macrophage inhibitory factor inhibitor, had transient sedative effects, but it restored the antinociceptive effect of morphine in morphine-tolerant rats after single and repeated administration. It did not prevent the development of opioid tolerance. Atipamezole, an alpha-2-adrenoceptor antagonist used for the reversal of sedation in animals during anesthesia, was effective in augmenting intrathecal morphine antinociception in both opioid-naïve and opioid-tolerant animals. These effects were observed at doses lower than those required for the antagonism of alpha-2-adrenoceptors. In subcutaneous administration, low doses of atipamezole did not influence morphine antinociception. The mineralocorticoid receptor antagonist spironolactone dose-dependently enhanced morphine antinociception. This effect was mediated via the increased access of morphine to the central nervous system by the inhibition of the efflux protein P-glycoprotein. Spironolactone did not inhibit the metabolism of morphine to the pronociceptive metabolite morphine-3-glucuronide, and it did not prevent the development of opioid tolerance. The effects of ketamine in augmenting opioid analgesia in tolerance are thought to result from a beneficial pharmacodynamic interaction. When acute ketamine was administered to rats under chronic morphine treatment, the brain concentrations of morphine, ketamine and norketamine were increased compared with the situation where either morphine treatment or acute ketamine were administered alone. The results indicate a potentially beneficial pharmacokinetic interaction between the two drugs. The results of the thesis study demonstrate that ibudilast and atipamezole modulate nociception at systemic and spinal levels in preclinical models of pain, and they may prove advantageous as an adjuvant to opioid therapy. Spironolactone had a pharmacokinetic interaction with morphine, leading to increased morphine concentrations in the central nervous system. Ketamine, a drug used for the treatment of opioid tolerance in cancer patients, may undergo previously unrecognized beneficial pharmacokinetic interactions with morphine.
  • Kolehmainen, Pekka (Helsingin yliopisto, 2014)
    Human parechovirus (HPeV) and Ljungan virus (LV) are non-enveloped, single-stranded RNA viruses that form the genus Parechovirus in the family Picornaviridae. The interest in these viruses has notably increased over the past 15 years because of their strengthened associations to human and animal diseases. HPeV types 1 and 3 have been associated with more severe infections in young children, such as infections of the central nervous system (CNS) and sepsis-like disease. Rodent-infecting LV has been suggested to possess zoonotic potential and induce various human diseases. However, the proof for this remains lacking. This study aimed to describe the epidemiological features of HPeVs in Finland and in the Netherlands, to examine the connection between HPeV-induced infection and human diseases and to study the circulation of LV in Finland. The epidemiological analysis of stool samples, collected from 1996 to 2007, revealed that HPeVs are highly common in healthy Finnish children. HPeV was primarily detectable in children under 2 years of age. Altogether, 39% of the study participants tested positive for HPeV at least once during the study period. HPeVs circulated throughout the year, with a distinct seasonal peak in October-November. The results indicated that not only the previously described HPeV1 but also HPeV genotypes 3 and 6 circulate in Finland. Microneutralisation assays, which were set up to detect HPeV1 to 6, the most common genotypes in Europe, provided a deeper understanding of HPeV seroprevalence in the Finnish and Dutch populations. Seropositivity for HPeV1, 2 and HPeV4 to 6 was high and moderate in adults, in contrast to seropositivity for HPeV3, which was extremely low. The serological data demonstrate that HPeV types 1 to 6 might be even more prevalent than previously assumed. All six HPeV types circulate in Finland. In addition to HPeV detection in background populations, we presented the first cases of severe infection in neonates with HPeV4 and, subsequently, the first isolation of this genotype in Finland. Five hospitalised neonates with a sepsis-like disease in the fall of 2012 were positive for HPeV. Four of these children had HPeV4, indicating a potential small epidemic of this genotype, whereas one HPeV remained untyped. In addition, we detected HPeV3 in a neonate with suspected viral sepsis in October 2011 and another untyped HPeV in a child with symptoms corresponding to acute disseminated encephalomyelitis in May 2012. Following these findings, we promoted the addition of HPeV detection to routine diagnostics of young children. To extend the knowledge regarding other parechoviruses in Finland, we studied LV antibody prevalence in both humans and rodents. The seroprevalence detected for LV was 38% in humans and 18% in bank voles (Myodes glareolus). The observation of LV antibodies in humans is relatively high because LV has never been isolated from humans. These results suggest that an LV or LV-like virus, in addition to HPeVs, circulates frequently among human populations in Finland.
  • Ketola, Sirpa (Helsingin yliopisto, 2014)
    Vertigo and dizziness are among the most frequent complaints in primary care. The symptoms are usually self-limited, and the clinical course is benign, with full recovery. In many cases, however, vertigo and dizzy spells recur, leading to impairment and chronic outcome. A number of studies have documented a high prevalence of psychiatric comorbidity in vertiginous patients. Vertigo and dizzy symptoms themselves can provoke psychological distress, because recurrent unpredictable attacks can induce fear of losing control, concern of serious illness, and worry about severe attacks compromising one s ability to adapt. Recurrent spells can also provoke earlier mental problems. Yet the degree of subjective handicap and emotional distress has shown no close relationship to measures of vertigo symptom severity. Psychiatric disorders do not cause vertigo or dizziness, but can, together with vertigo and dizzy symptoms, lead to persistent complaints. Anxiety and depression are the most common disorders associated with vertigo and dizziness. Vertigo and dizziness in children is not rare. One population-based study found a prevalence of vertigo of 14% (Russell and Abu-Arafeh 1999). The etiology varies, but usually involves organic causes. Psychiatric etiology is investigated only after the exclusion of organic etiology. Psychosomatic symptoms are common in children and adolescents, often reflecting problems in psychosocial background. The first study aimed to evaluate the adapting ability of patients with Ménière s disease based on the sense of coherence scale. Data were collected with two different postal questionnaires involving 547 recipients (Study I). Studies II and III evaluated the prevalence of psychiatric symptoms in vertiginous patients. This study group comprised 100 vertiginous subjects from a randomly selected community sample participating in a vertigo prevalence study in the Helsinki University Hospital district. The investigative program entailed a neuro-otological examination and psychiatric evaluation in questionnaire form. Study IV assessed the prevalence of psychiatric disorders in a group of 119 children and adolescents between the ages of 7 months to 17 years who had visited the ear, nose and throat clinic with a primary complaint of vertigo. An otologist and a psychiatrist reviewed and evaluated each patient s detailed medical history. The results indicate a high sense of coherence (SOC) to represent deeper contentment in life and less psychological distress despite the chronic disease. Although SOC scores did not relate to the severity of illness, subjects with low SOC scores exhibited more symptoms of both vertigo and psychological distress (Study I) than did subjects with high SOC scores. In Studies II and III, the prevalence of depressiveness was 19%, and the prevalence of symptoms of anxiety, 12%. A total of 68% of subjects reported psychiatric symptoms, the most common of which was personality disorder. Comorbidity between depressive, anxiety and personality symptoms were ample and related significantly to reduced functional capacity. In Study IV, the prevalence of psychogenic vertigo was 8%. Major depression was the most common disorder, and 2.5% of patients suffered from somatization disorder. The psychiatric distress commonly reflected psychosocial problems and affected seriously on daily life functioning. In conclusion, this study found that psychiatric symptoms are common in vertiginous patients. Comorbidity may lead to a more debilitating course of vertigo independently of an organic cause or the severity of vertigo symptoms. Feelings of disability correlated with psychological distress. In children and adolescents, vertigo symptoms with compromised daily functioning, together with psychosocial stress factors, should invoke at least the possibility of psychiatric distress. Keywords: vertigo, depression, anxiety, personality disorder, comorbidity, disability, coping, chronic 
  • Kanerva, Noora (Juvenesprint, 2014)
    Obesity causes metabolic dysregulations that increase the risk of cardiovascular disease (CVD) and type 2 diabetes (T2D). Diet is known to play a key role in preventing obesity. In epidemiological studies, because single food and nutrient studies focusing on obesity have produced generally inconsistent results, nutrition researchers have shifted to exploring the health related effects of the whole diet, measured with dietary scores. Recently, a diet constructed of healthy Nordic foods has been suggested as having obesity and metabolic health enhancing features. However, there is a lack of population-based studies on this topic. The aim of the research presented in this thesis was to develop a dietary score reflecting the healthy Nordic diet, and to assess its associations with obesity, metabolic risk factors (e.g., low-grade inflammation, lipid fractions) and T2D in an epidemiological setting. This study was based on data from three health surveys conducted between 2001-2007: the DILGOM study (n = 5024), the Health 2000 survey (n = 6772), and the Helsinki birth cohort study (HBCS) (n = 2003). In clinical examinations, the weight, height, waist circumference and blood pressure of participants were measured, and blood samples were drawn. Information on the past medical history was derived from nationwide health registers. Participants habitual diet was assessed with a validated food frequency questionnaire, which was used to derive the Baltic Sea Diet Score (BSDS) reflecting the healthy Nordic diet. The BSDS included nine components typical of the Nordic diet, which were scored according to the predictable health effect of each component, using sex- and population specific quartile cut-offs. The final summary score ranged between 0-25 points. Participants with high adherence to the healthy Nordic diet (BSDS ≥ 17) had significantly higher intake of carbohydrates, fibre, vitamins, minerals and sodium, and lower intake of saturated fat and alcohol compared to those who did not adhere to the diet (BSDS ≤ 9). Moreover, those who adhered to the diet were 35-52% less likely to be abdominally obese and 27-42% less likely to have elevated C-reactive protein (CRP) concentrations compared to the others. In contrast, women adhering to the healthy Nordic diet were 40% more likely to have a low concentration of high-density lipoprotein (HDL) cholesterol than the others. The BSDS did not associate with T2D incidence during 10 years of follow-up. In conclusion, the BSDS appears to be a valid tool for measuring adherence to a healthy diet. The findings related to abdominal obesity and low-grade inflammation, if proven causal, may lead to decrement in chronic disease risk, and therefore, be relevant from the public health perspective.
  • Wasik, Anita Agnieszka (Helsingin yliopisto, 2014)
    Diabetic nephropathy (DN) is a major microvascular complication of diabetes and a common cause of end-stage renal disease. Mechanisms leading to the development of DN are not fully understood, but podocyte injury is involved. Interestingly, in respect to glucose uptake podocytes are uniquely insulin sensitive cells. Insulin rapidly induces remodeling of the actin cytoskeleton and leads to glucose uptake via glucose transporters GLUT1 and GLUT4. Defects in the trafficking of the glucose transporters may affect the insulin sensitivity of podocytes. Thus, regulators of glucose transporter trafficking may provide suitable targets to enhance insulin sensitivity of podocytes and prevent the development and progression of DN. However, the precise mechanisms regulating glucose transporter trafficking and glucose uptake into podocytes are largely uncharacterized. To identify changes in the expression of glomerular proteins at an early stage of DN we performed quantitative proteomic profiling of glomeruli isolated from rats with streptozotocin-induced diabetes and controls. Ezrin was found to be downregulated in diabetic glomeruli. In cultured podocytes depletion of ezrin increased glucose uptake by increasing translocation of GLUT1 to the plasma membrane. Loss of ezrin also induced actin remodelling, which involved cofilin-1. Phosphorylated cofilin-1 was upregulated in diabetic glomeruli suggesting altered actin dynamics. Furthermore, reduced expression of ezrin was found in the podocytes of human patients with diabetes. We found that the filament-forming septin 7 forms a complex with CD2AP and nephrin, both of which are essential for glomerular ultrafiltration. We showed that septin 7 negatively regulates GLUT4 storage vesicle (GSV) trafficking by forming a physical barrier between the vesicles and the plasma membrane. The novel interaction partner of septin 7, nonmuscle myosin heavy chain IIA (NMHC-IIA), was found to positively regulate insulin-stimulated glucose uptake into podocytes. Loss of NMHC-IIA reduced formation of the SNARE complex involved in GSV exocytosis. Furthermore, we presented that insulin regulates the association of septin 7 and phosphorylated RLC (pp-RLC), a part of myosin hexameric complex, with a plasma membrane SNARE, SNAP23. pp-RLC is upregulated in diabetic glomeruli and cultured human podocytes exposed to macroalbuminuric sera from patients with Type 1 diabetes. Our findings indicate that ezrin, septin 7 and NMHC-IIA regulate glucose uptake into podocytes and may play a role in the development of the renal complication in diabetes by regulating glucose transport and organization of the actin cytoskeleton in podocytes.
  • Mattsson, Johanna (Helsingin yliopisto, 2014)
    Prostate-specific antigen (PSA) is a very useful biomarker for prostate cancer. The PSA concentration in circulation increases due to leakage of PSA from cancerous tissue. Normally PSA, a serine protease with chymotrypsin-like enzymatic activity, is secreted into seminal fluid by the epithelial cells of the prostate. The major physiological function of PSA in seminal fluid is to digest semenogelins, which leads to liquefaction of the seminal clot. Several other functions have also been suggested for PSA, some of which are associated with cancer. PSA exerts antiangiogenic activity, but PSA may also promote tumor growth and metastatic dissemination. The aim of the research presented in this thesis was to characterize the antiangiogenic and proteolytic activities of PSA. One of the main goals was to elucidate whether the enzymatic activity of PSA is a requirement for its antiangiogenic activity. The antiangiogenic activity of PSA was studied using an in vitro angiogenesis model based on tube formation of human umbilical vein endothelial cells (HUVEC). In this model only enzymatically active PSA was able to inhibit angiogenesis. Peptides that stimulate the proteolytic activity of PSA enhanced the antiangiogenic activity, while small molecule compounds that inhibit PSA abolished this activity. DNA microarray study showed that PSA-induced changes in the gene expression of HUVECs were small during tube formation, and it was not clear whether these changes were primary or secondary to the antiangiogenic activity of PSA. The results of this thesis suggest that the antiangiogenic activity of PSA is mediated by a proteolytic product generated by PSA. The proteolytic activity of PSA was studied using several peptide and protein substrates. Semenogelins are the major physiological substrates of PSA and they were shown to be degraded much more rapidly than any other protein substrate studied. Nidogen-1, a component of the basement membrane, was identified as a novel substrate for PSA by mass spectrometry. However, the cleavage of nidogen-1 did not explain the antiangiogenic activity of PSA, since either its fragments or full-length form did not affect HUVEC tube formation. Contrary to a previous report, we showed that the antiangiogenic activity of PSA was not mediated by angiostatin-like fragments generated by the cleavage of plasminogen. The results of this thesis established that the proteolytic activity is necessary for the antiangiogenic activity of PSA and that the antiangiogenic activity can be enhanced by PSA-stimulating peptides and abolished by PSA-inhibitors. The comparison of the efficiency of PSA to cleave different protein substrates and the identification of nidogen-1 as one of these substrates provided new information about the biological role of PSA. The typically slow growth of most prostate cancers may be caused by the antiangiogenic activity of PSA, as there are high concentrations of active PSA present in prostatic tissue. Therefore, peptides that stimulate the antiangiogenic activity of PSA and reduce tumor angiogenesis could be used to control prostate cancer growth.
  • Hautamäki, Hanna (Helsingin yliopisto, 2014)
    Hot flushes, the most characteristic symptoms in menopause, are encountered by c.a. 80% of women. Hot flushes and other menopausal complaints can significantly impair a woman s quality of life. Additionally, the majority of women experience premenstrual symptoms in their fertile age. Due to the resemblance between premenstrual and menopausal symptoms, women with severe premenstrual symptoms might fear for an increased risk of developing menopausal complaints, such as vasomotor symptoms. It is, however, unclear why some women experience intolerable hot flushes while others remain completely asymptomatic. Hot flushes are characterised by cardiovascular reactions such as rapid episodes of reddening of skin and palpitations. Thus, women with or without hot flushes may differ in their cardiovascular reactivity and responses to hormone therapy. The present study was designed to investigate the impact of hot flushes and different forms of hormone therapy on health-related quality of life and cardiovascular autonomic function. Therefore, 150 healthy, recently postmenopausal women showing a large variation in hot flushes were studied before and during six months of hormone therapy. Hot flushes were evaluated prospectively with a two-week hot flush diary. The relationship between a history of premenstrual symptoms and the postmenopausal quality of life and hot flushes was also assessed. The cardiovascular autonomic function was studied with a standardised test series in controlled laboratory settings. Hot flushes were important determinants for the decreased health-related quality of life in menopause. Previous premenstrual symptoms lacked correlation with the severity of postmenopausal hot flushes but associated with deterioration of health-related quality of life, seen as poor sleep, depressive feelings and impaired memory and concentration. Women with hot flushes reacted with more tachycardia and slightly blunted parasympathetic activity in heart rate responses to cardiovascular autonomic testing compared with asymptomatic women. In a randomized study, all hormone therapy regimens alleviated hot flushes and other menopausal symptoms equally effectively. In women with pre-treatment hot flushes, hormone therapy improved health-related quality of life in terms of sleep, anxiety and fears, memory and concentration, and general health. Hot flushes were accompanied with lowered resting blood pressures but increases in blood pressure responses to physical strain during all hormone therapy regimens. Estradiol treatment lowered resting heart rate and reduced maximal heart rate in response to physical strain in women with pre-treatment hot flushes. This beneficial effect on heart rate was attenuated by adding medroxyprogesterone acetate to estradiol treatment. In conclusion, the hot flush status and hormone therapy contribute to cardiovascular autonomic function. Hot flushes seem to associate with slightly pronounced sympathetic responses in autonomic regulation of heart rate and blood pressure, which can be considered unbeneficial for cardiovascular function. This possibly unfavourable sympathetic activity can be reduced with estradiol treatment especially in women with hot flushes, who are potential candidates for hormone therapy in clinical practice. Hot flushes impair the health-related quality of life in recently postmenopausal women, but can be effectively alleviated with hormone therapy. Premenstrual symptoms do not predict severe hot flushes in menopause, which is comforting for women having troublesome premenstrual symptoms.
  • Järvinen, Petrus (Helsingin yliopisto, 2014)
    Abstract Pseudomyxoma peritonei (PMP) is best treated by surgery. It was formerly treated by serial debulking. The current gold standard is complete cytoreductive surgery (CRS) to be followed by hyperthermic intraperitoneal chemotherapy (HIPEC). Improved survival figures for patients treated by CRS and HIPEC combined have been reported recently. The aim of this PhD research was to evaluate (I) the outcome of patients treated by serial debulking in Helsinki University Central Hospital, (II) investigate the clinical manifestation of the disease, (III) assess the feasibility of CRS and HIPEC modality in combination, and (IV) compare results of serial debulking and CRS with HIPEC in patients with PMP. The surgical data and the survival outcome of 33 patients that were treated by serial debulking were analyzed in study I. The symptoms and signs of 82 patients with PMP were investigated in study II. Study III included 90 patients, who were evaluated in our facility and then given HIPEC when practicable. The characteristics that were associated with technically successful administration of HIPEC were analysed. The outcome of 87 patients treated in the HIPEC era was compared with those treated before the HIPEC era in study IV. The 5-year and 10-year overall survival (OS) rates were 67% and 31%. Four patients (12%) presented with no apparent evidence of disease at the completion of follow-up (I). The most common symptom of PMP was abdominal pain in 23% of the cases (II). Of 53 women, 26 (49%) underwent their initial operations because of presumed ovarian tumour. Of 29 men, 13 (45%) underwent their initial operations with a suspicion of PMP. Of the 90 patients assessed, 56 (62%) were feasible for HIPEC (III). Low-grade tumour (P=0.013), age under 65 (P=0.004), and serum CEA under 5.0µg/L (P=0.003) were associated with successful administration of HIPEC. The 5-year OS rates were 69% for the HIPEC era and 67% for the debulking era (IV). The proportion of patients who presented with no evidence of disease was higher for the HIPEC-era group than for the debulking-era group (54% vs. 24%). Patients who were treated by CRS and HIPEC combined managed well, but it is unfeasible to deliver HIPEC to every patient. A comparison of the 5-year OS rates of HIPEC era with those of the debulking era showed them to be approximately equal, when the whole patient population was included for the comparison. The natural progression of PMP is slow and thus the survival difference may only become apparent in follow-up periods in excess of 5-years. The proportion of patients who had undergone curative treatment may be higher in the HIPEC era.
  • Karhunen, Janne (Helsingin yliopisto, 2014)
    Sudden hemodynamic collapse after coronary artery bypass surgery is a major complication associated with high mortality and morbidity. There are many well-established risk stratification systems to assess the risk of mortality and morbidity after cardiac surgery. These risk scores, however, do not predict severe immediate postoperative complications such as sudden hemodynamic collapse. This study is based on analysis of patients who suffered from hemodynamic collapse early after coronary artery bypass surgery between 1988 and 1999 in Helsinki University Hospital. One matched control patient was selected for every study patient. Patients, who died, underwent a medico-legal autopsy and a rubber cast angiography to reveal possible surgical errors in myocardial revascularization. Patients still alive in 2009 were traced with respect to mortality data and a health-related quality of life questionnaire was sent to the patients and to the controls. In addition, a comparison was made between patients who suffered from postoperative hemodynamic collapse and patients who underwent a postoperative angiography due to persistent myocardial ischemia. Angiography was introduced in 2000 and this patient series was collected prospectively between 2000 and 2007. This thesis consists of four studies. The specific goals were to explore predictive factors of sudden hemodynamic collapse, to reveal the possible surgical errors that led to hemodynamic collapse and fatal outcome with the means of an autopsy, to find out the impact that postoperative angiography has on the incidence of hemodynamic collapse, and the rate of mortality, and morbidity of patients, and to investigate the quality of life of patients surviving hemodynamic collapse in comparison with an age- and sex-matched national reference population. The results suggest the following: Sudden hemodynamic collapse after CABG is a major complication with high mortality. Inadequate tissue perfusion, postoperative myocardial ischemia, and increased need for inotropic as well as mechanical support are predictive of hemodynamic collapse. Technical graft complications are a major underlying cause of postoperative hemodynamic collapse. Post-mortem angiography improves the accuracy of diagnostics of graft complications. The cause of death could be established in every case. Use of early postoperative angiography in case of hemodynamic compromise or myocardial ischemia reduces the rate of emergency reoperations and decreases morbidity and mortality. It also allows treatment with intravascular medication. Patients who survive hemodynamic collapse and emergency reoperations have a similar prognosis as matched control patients. Health-related quality of life that is also comparable with age- and sex-matched national reference population as long as 15 years postoperatively.
  • Molander, Pauliina (Helsingin yliopisto, 2014)
    In the era of TNFα-blocking therapy, MH and even DR have been suggested as new therapeutic targets in both CD and UC. Recent studies have indicated that DR may be achieved in roughly half of IBD patients on TNFα-blocking maintenance therapy, resulting in more favorable treatment outcomes. However, considering the potential side-effects and economic issues associated with long-term immunosuppressive therapy with TNFα-blocking agents, the possibility of discontinuing therapy should be evaluated at least once after achieving DR. At present, no widely accepted recommendations for discontinuing TNFα-blocking therapy are available. Based on the results of our study, only for about half of patients in DR were candidates for discontinuation of TNF-blocking medication for various reasons. Nevertheless, up to 67% of IBD patients in DR at the time of cessation of TNFα-blocking therapy remained in clinical remission during the 12-month follow-up, and moreover, the majority of these patients also remained in endoscopic remission. Therefore, withdrawal of therapy could be considered in IBD patients in DR even after one-year treatment. Reassuringly, in case of a relapse, the response to restart of TNFα-blocking therapy seems to be effective and well-tolerated. To evaluate treatment response and possible relapse during maintenance therapy or after discontinuation of TNFα-blocking therapy, FC seems to be a reliable surrogate marker to replace endoscopic assessment. A normal FC after induction with TNFα-blocking agents predicts sustained remission in the majority of patients with active luminal disease receiving scheduled treatment. However, an objective cut-off value for treatment response and relapse risk is to some extent still undefined. To predict IBD relapse and identify patients requiring a close follow-up in clinical practice, FC seems to be a useful surrogate marker, as it increases and remains elevated as early as 6 months before symptomatic relapse. FC measurements should therefore be included in monitoring IBD patient s treatment response in everyday clinical practice.
  • Filppula, Anne (Helsingin yliopisto, 2014)
    The drug-metabolising enzyme cytochrome P450 (CYP) 2C8 is involved in the elimination of several important drugs. The asthma drug montelukast inhibits CYP2C8 potently in vitro, but does not affect the pharmacokinetics of CYP2C8 substrates in vivo. In turn, the cancer drug imatinib is a CYP2C8 and CYP3A4 substrate in vitro, but CYP3A4 inhibitors have little effect on its concentrations in vivo. This thesis aimed to examine these discrepancies, and to study the role of CYP2C8 in the metabolism of montelukast and imatinib. The work comprised in vitro experiments, physiologically based pharmacokinetic (PBPK) simulations, and two interaction studies with a two-phase, placebo-controlled crossover design in healthy subjects. In vitro, CYP2C8 metabolised montelukast extensively. In the clinical study, the strong CYP2C8 inhibitor gemfibrozil increased the area under the plasma concentration time-curve (AUC) of montelukast by 4.5-fold in healthy subjects, thus suggesting that CYP2C8 contributes to ~80% of its elimination. In vitro, imatinib was mainly metabolised by CYP2C8 and CYP3A4, but imatinib also inhibited CYP3A4 irreversibly. In vivo, gemfibrozil unexpectedly reduced imatinib absorption, while it had no effect on imatinib AUC. However, the AUC of the main metabolite of imatinib decreased by ~50%. PBPK simulations suggested that the findings could be explained by a complex interaction involving simultaneous inhibition of an uptake transporter involved in imatinib absorption and of CYP2C8 by gemfibrozil. Furthermore, the simulations proposed that the elimination of imatinib during steady state relies more on CYP2C8 than on CYP3A4, because of CYP3A4 autoinhibition by imatinib. Inhibition of CYP3A4 by imatinib also suggests that concomitant use of imatinib with CYP3A4 substrates may lead to harmful interactions. The findings of this work explain the previously documented in vitro-in vivo inconsistencies and provide important information for a safe use of these drugs. CYP2C8 inhibitors may increase the effect and adverse reactions of montelukast and imatinib. On the other hand, because montelukast is generally well-tolerated and CYP2C8 seems to play a key role in its elimination, these data suggest that it could serve as a CYP2C8 probe in interaction studies. Collectively, the studies of this work strengthen the role of CYP2C8 as an important drug-metabolising enzyme.
  • Tuuminen, Raimo (Helsingin yliopisto, 2014)
    Transplant ischemia/reperfusion injury (Tx-IRI) remains among the major clinical challenges in organ transplantation. Tx-IRI may result in deleterious short-term consequences such as primary graft dysfunction and increased immunogenicity of the allograft, both of which enhance the propability for late vascular remodeling and fibroproliferative processes, ultimately leading to untreatable chronic allograft dysfunction and compromised long-term survival. The underlying mechanisms in primary graft dysfunction involve microvascular dysfunction culminating in increased vascular permeability, perfusion defects, and leukocyte infiltration into the allograft, which may lead to pro-inflammatory and pro-fibroproliferative prosesses. The pleiotropic, cholesterol-independent vasculoprotective effects of statins, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, have been well described. Statins improve microvascular integrity and perfusion through endothelial cell (EC) and pericyte function. Statins attenuate the expression and secretion of angiogenic growth factors and microvascular reactivity at the site of vascular injury. Statins seem to have also anti-inflammatory, -oxidative, and -thrombotic effects. They are widely used for primary and secondary prevention of cardiovascular disease. In the transplant recipients, statin treatment decreases allograft inflammation and vasculopathy and cardiovascular morbidity. However, the therapeutic potential of donor statin treatment against Tx-IRI and microvascular dysfunction remains undelineated. The majority of potential cardiac allograft donors from brain-dead donors do not have previous medical track record of cardiovascular diseases nor statin medication. The heart is especially susceptible to donor brain death that elicits cardiotoxic pro-inflammatory cytokine release, cardiovascular disintegration and poor organ perfusion, which often lead to disqualification of a transplant. On the other hand, shortage of donors and different donor-related factors limit the availability of transplants, and thus lead to the use of organ donors with extended criteria such as older age. Aggressive donor management could not only improve the quality of donated organs, but also expand the donor pool by increasing suitability of donors with extended criteria and thus reduce costs of transplantation affecting e.g. need for inotropic support and stay at intensive care unit. Based on these clinically relevant issues, we chose pharmacological approaches to treat donors to improve allograft resistance to Tx-IRI and primary and and chronic allograft dysfunction. Donor rats without brain death were treated with a single peroral dose of lipophilic simvastatin two hours before heart and kidney removal, which is the clinical time-window to treat a brain-dead organ donor. The cardiac allografts were subjected to 4-h and kidney allografts to 16-h cold-ischemic preservation to mimic clinical situation and transplanted to fully major histocompatibility complex (MHC)-mismatched WF rat recipients. As our current clinical practice includes donor treatment with high dose of methylprednisolone, that modulates inflammatory state after brain death, we also investigated whether combined donor simvastatin and methylprednisolone treatment could be superior to either treatment alone on Tx-IRI and allograft survival. Here, we report that the expression of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, a target molecule of statins, was abundant in endothelial cells (ECs) and pericytes of normal hearts as well as in glomerular and peritubular microvascular structures of normal kidneys. Rat cardiac and kidney allograft Tx-IRI resulted in profound microvascular dysfunction; leakage, perfusion defects and increased adhesivity. Donor, but not recipient treatment with peroral single-dose simvastatin two hours before graft procurement inhibited microvascular EC and pericyte RhoA/Rho-associated protein kinase activation and inter-EC gap formation, vascular leakage, the no-reflow phenomenon, danger-associated ligand hyaluronan induction, leukocyte infiltration and myocardial and tubulointersitital injury. In the chronic rejection model, donor simvastatin treatment inhibited cardiac allograft inflammation, TGF-β1 signaling and myocardial fibrosis, vasculopathy and improved long-term allograft survival. Furthermore, donor treatment with a combination of simvastatin and methylprednisolone was superior in the prevention of Tx-IRI and significantly prolonged acute survival of non-immunosuppressed major MHC-mismatched cardiac allograft. In conclusion, donor treatment may target microvascular dysfunction, immunomodulation and the initiation of pro-inflammatory and pro-fibroproliferative pathways in cardiac and kidney allografts subjected to prolonged ischemia time using a protocol relevant for clinical cadaveric transplantation. Minimizing microvascular injury and the activation of innate immunity by combined donor simvastatin and methylprednisolone treatment may offer a novel therapeutic strategy to expand the donor pool and furthermore improve the function of donor organs with extended criteria. We have therefore initiated a randomized clinical trial to investigate the effect of combined donor simvastatin and methylprednisolone treatment as an adjunct therapy on short- and long-term results of cardiac and kidney allografts.
  • Roos, Eira (Helsingin yliopisto, 2014)
    Obesity and overweight are common among working aged population. Obesity is associated with a number of long-term illnesses as well as increased mortality. Previous studies have found that obesity is also associated with some forms of work disability. However, longitudinal studies with register-based large data sets are scarce. The aim of this study was to examine the association between working conditions and subsequent weight gain as well as the associations between body weight, weight change and subsequent work disability in a cohort setting among middle-aged employees. This study is part of Helsinki Health Study (HHS), a cohort study on employees of the City of Helsinki. The data consists of a baseline mail questionnaire survey sent in 2000-2002 to 40-, 45-, 50-, 55- and 60-year old employees (respondents n=8960) and a follow-up questionnaire survey sent to the respondents of the baseline survey in 2007 (respondents n=7332). Questionnaire surveys yielded data on a wide range of factors such as socio-economic determinants, health and working conditions. The data from the surveys were combined with data from health check-ups that were carried out among the employees of the City of Helsinki during 2000-2002. The data were additionally linked with register data on employees sickness absence spells and disability retirements from the Finnish Centre for Pensions. Logistic regression analyses, the Cox proportional hazards model and Poisson regression analyses were used as statistical methods. A number of confounding factors were controlled for the analysis, including working conditions, health behaviours, previous health, and physical and mental functioning. Weight gain was common as one in four employees experienced major weight gain during the 5-7 year follow-up. For most of the studied working conditions, no association with weight gain was observed. Night shift work, work that was characterized as having hazardous exposures, passive work, and work where facing physical violence or threats was common were weakly associated with major weight gain. Both obesity and weight change (even among normal-weight employees) were associated with subsequent sickness absence. Obesity increased the risk of long spells of sickness absence in particular, but also elevated the risk of short spells. Weight loss, weight gain and stable obesity increased the risk of sickness absence spells of all lengths. Obesity was strongly associated with disability retirement due to musculoskeletal diseases, and to a lesser degree to mental disorders and other causes. Following adjustment for earlier health, working conditions and functioning, the association between obesity and long sickness absence spells and disability retirement was somewhat attenuated. The results of this study show that weight gain is common among middle-aged employees and that the studied working conditions are weakly or not at all associated with weight gain. The findings also indicate that weight gain and obesity are clearly and consistently associated with both temporary and permanent work disability. Obesity is thus not only a public health issue but also affects occupational health and work ability. Prevention of obesity and weight gain is increasingly important in primary health care as well as in occupational health care.
  • Scifo, Enzo (Helsingin yliopisto, 2014)
    Neuronal ceroid lipofuscinoses (NCL) are common inherited childhood brain disorders. Since 1995, 13 known NCL causative genes (CLN1-8, CLN10-14) have been identified. Despite progress in the NCL field, the primary function and physiological roles of most NCL proteins remain unresolved. In this thesis, we utilized various techniques, such as: functional proteomics, bioinformatics, and mouse disease models, in an effort to clarify disease pathways associated with congenital (CLN10), infantile, late-Infantile (CLN1, CLN5) and juvenile NCL (CLN3) in the human brain. Firstly, we examined the synaptic proteome in a cathepsin D (Ctsd / Cln10) knockout mouse model of congenital NCL, where the synaptic pathology resembles that of patients. Quantitative mass spectrometry analysis of mouse brain synaptosomes, showed that 43 proteins were differentially expressed in the Ctsd knockout mice brains. We used protein-protein interaction databases to generate a network of differentially expressed proteins and checked individual proteins for involvement in processes, pathways or disease phenotypes. This work highlighted defects in migratory functions of cathepsin D deficient cells that were attributed to downregulation of cytoskeletal proteins. We also aimed to map the CLN3-CLN5 protein interactome in the brain by identifying their associated proteins. Protein complexes from CLN3 or CLN5 expressing SH-SY5Y stable cells were analysed by mass spectrometry and processed by bioinformatics, to unravel molecular mechanisms underlying CLN3 and CLN5 diseases. Novel CLN3 and CLN5 interacting partners (42 and 31, respectively) were identified in this study. The extent of crosstalk amongst CLN3 and CLN5, suggests that the mechanisms leading to the functional deficits are shared between them. CLN3 was implicated in new roles of G-protein signalling and protein folding / sorting in the ER. Finally, we analysed protein complexes from human PPT1 (CLN1) expressing SH-SY5Y stable cells as described above. The goal of this study was to identify in vivo PPT1 substrates that could provide insight on the onset and progression of CLN1 disease. Our findings suggest putative new roles of PPT1 in neuronal migration and dopamine receptor mediated signalling pathway.
  • Surakka, Ida (Helsingin yliopisto, 2014)
    Circulating blood lipids are well-established risk factors for cardiovascular diseases. Levels of high-density lipoprotein, low-density lipoprotein, total cholesterol, and triglycerides are affected by environmental and genetic factors. As the genetic factors explain around half of the population lipid variation based on twin studies, knowledge of the genetic determinants is crucial in prevention and early treatment of harmful lipid levels. In this thesis, genetic markers associated with lipid levels were screened using genome-wide marker datasets to better understand the biological and heritable mechanisms behind lipid levels. To identify different types of associated loci, genome-wide single nucleotide polymorphism (SNP) data from multiple European cohorts was combined. In addition, this thesis presents the effect of using Finnish imputation panel as reference on the quality of genotype imputation, which enables the usage of denser SNP marker sets in association analysis. In total, 95 genetic loci with genome-wide significant association (P-value less than 5×10-8, accounting for one million independent tests) on lipid levels were identified. In one of these loci, the SNP genotype modified the association between total cholesterol and waist-to-hip ratio. Common genetic markers found in the first publication together with the previously associated loci in publications of other research groups explained up to 4.8% of the lipid level variation. When combining all the genetic information available from different sources at the end of this thesis project, up to 16.6% of the trait variation could be explained, which corresponds to 33% of the trait heritability. In the work described in this thesis almost a hundred genetic loci associated to circulating blood lipids were successfully identified using large-scale genome-wide approaches. This thesis demonstrates new biology behind lipid levels, in addition to how large scale studies with dense SNP panels enabled by genotype imputation, can be a key in revealing biological determinants behind complex diseases and traits. Keywords: Circulating blood lipids, genome-wide association, gene-environment interaction, genotype data imputation
  • Sahi, Helka (Helsingin yliopisto, 2014)
    Background and purpose: Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer, with a high tendency to both relapse and metastasize. 70-80% of MCCs carry the recently detected Merkel cell polyomavirus (MCV). MCV integrates clonally into the tumour genome and harbors specific mutations, which suggest a causal role in the tumorigenesis. Predispositional factors for MCC include advanced age, Caucasian race and immunocompromising states. The purpose of this study was to examine the etiological factors of MCC, particularly in the subgroups of immunodeficient and unusually young MCC patients. We also aimed to elucidate the biology and molecular mechanisms underlying the pathogenesis of the subgroup of tumours that do not present with MCV. Methods: In the clinicopathological studies (I, IV and V), we combined clinical data derived from the Finnish Cancer Registry and patient records with biological features of MCC. All MCC diagnoses were confirmed histologically from the primary tumour paraffin blocks used as samples in the molecular analyses. MCV was analysed by quantitative PCR of the tumour samples. Expression of bcl-2 and RB proteins were examined by immunohistochemistry of tissue array blocks constructed from the primary tumour samples. Chromosomal aberrations were determined with array genomic hybridization, and the methylation of the RB1 promoter with methylation-specific multiplex ligation-dependent probe amplification technique. Standard statistical methods were employed to compare the findings between MCV-negative and positive tumour subgroups, and between patients younger and older than 50 years of age. In the epidemiological studies (II and III) we utilized record linkage of the Finnish Cancer Registry and the National Prescription Register of the Social Security Institution. A case-control study with all MCC patients diagnosed in Finland was conducted to determine the role of autoimmune diseases as predictors of MCC. The effects of statin use on the incidence of MCC were studied in a cohort consisting of all statin users in Finland. Results: The young MCC patients were frequently immunocompromised and MCV-positive. Bcl-2 expression did not vary according to MCV status and was associated with good survival in both groups. MCV-negative tumours were found to be chromosomally more unstable than MCV-positive tumours, and to harbor more frequent deletions of the chromosome 11p and the RB1 locus (7.7% vs 38 %). The RB1 promoter was methylated in a distinctive pattern in MCC tumours, but did not vary according to MCV status. Autoimmune diseases in general (OR 1.63, 95%CI 1.19-2.22), and specifically rheumatoid and diabetic conditions, led to a predisposition for MCC. The incidence of MCC was significantly increased among young Finnish statin users (SIR 1.94, 95%CI 1.23-2.90). Paradoxically, the risk decreased significantly moving towards older age-groups of statin users. Conclusions: Based on our results, autoimmune diseases and statin use play a part in the pathogenesis of MCC. The unusually young patients included in our material were also often immunocompromised. MCC should be kept in mind when dealing with skin manifestations of these subgroups. RB1 deletions and chromosomal instability are of importance in the pathogenesis the MCV-negative MCC tumours, whereas no differences were observed in bcl-2 expression between the subgroups. These findings provide further evidence that MCV infection defines subgroups of MCC.