Browsing by Title

Sort by: Order: Results:

Now showing items 1222-1241 of 1630
  • Nyman, Heidi (Helsingin yliopisto, 2010)
    Diffuse large B-cell lymphoma (DLBCL) is the most common of the non-Hodgkin lymphomas. As DLBCL is characterized by heterogeneous clinical and biological features, its prognosis varies. To date, the International Prognostic Index has been the strongest predictor of outcome for DLBCL patients. However, no biological characters of the disease are taken into account. Gene expression profiling studies have identified two major cell-of-origin phenotypes in DLBCL with different prognoses, the favourable germinal centre B-cell-like (GCB) and the unfavourable activated B-cell-like (ABC) phenotypes. However, results of the prognostic impact of the immunohistochemically defined GCB and non-GCB distinction are controversial. Furthermore, since the addition of the CD20 antibody rituximab to chemotherapy has been established as the standard treatment of DLBCL, all molecular markers need to be evaluated in the post-rituximab era. In this study, we aimed to evaluate the predictive value of immunohistochemically defined cell-of-origin classification in DLBCL patients. The GCB and non-GCB phenotypes were defined according to the Hans algorithm (CD10, BCL6 and MUM1/IRF4) among 90 immunochemotherapy- and 104 chemotherapy-treated DLBCL patients. In the chemotherapy group, we observed a significant difference in survival between GCB and non-GCB patients, with a good and a poor prognosis, respectively. However, in the rituximab group, no prognostic value of the GCB phenotype was observed. Likewise, among 29 high-risk de novo DLBCL patients receiving high-dose chemotherapy and autologous stem cell transplantation, the survival of non-GCB patients was improved, but no difference in outcome was seen between GCB and non-GCB subgroups. Since the results suggested that the Hans algorithm was not applicable in immunochemotherapy-treated DLBCL patients, we aimed to further focus on algorithms based on ABC markers. We examined the modified activated B-cell-like algorithm based (MUM1/IRF4 and FOXP1), as well as a previously reported Muris algorithm (BCL2, CD10 and MUM1/IRF4) among 88 DLBCL patients uniformly treated with immunochemotherapy. Both algorithms distinguished the unfavourable ABC-like subgroup with a significantly inferior failure-free survival relative to the GCB-like DLBCL patients. Similarly, the results of the individual predictive molecular markers transcription factor FOXP1 and anti-apoptotic protein BCL2 have been inconsistent and should be assessed in immunochemotherapy-treated DLBCL patients. The markers were evaluated in a cohort of 117 patients treated with rituximab and chemotherapy. FOXP1 expression could not distinguish between patients, with favourable and those with poor outcomes. In contrast, BCL2-negative DLBCL patients had significantly superior survival relative to BCL2-positive patients. Our results indicate that the immunohistochemically defined cell-of-origin classification in DLBCL has a prognostic impact in the immunochemotherapy era, when the identifying algorithms are based on ABC-associated markers. We also propose that BCL2 negativity is predictive of a favourable outcome. Further investigational efforts are, however, warranted to identify the molecular features of DLBCL that could enable individualized cancer therapy in routine patient care.
  • Mrena, Johanna (Helsingin yliopisto, 2011)
    Background and aims: Low stage and curative surgery are established factors for improved survival in gastric cancer. However, not all low-stage patients have a good prognosis. Cyclooxygenase-2 (COX-2) is known to associate with reduced survival in several cancers, and has been shown to play an important role in gastric carcinogenesis. Since new and better prognostic markers are needed for gastric cancer, we studied the prognostic significance of COX-2 and of markers that associate with COX-2 expression. We also studied markers reflecting proliferation and apoptosis, and evaluated their association with COX-2. Our purpose was to construct an accurate prognostic model by combining tissue markers and clinicopathogical factors. Materials and methods: Of 342 consecutive patients who underwent surgery for gastric cancer at Meilahti Hospital, Helsinki University Central Hospital, 337 were included in this study. Low stages I to II were represented by 141 (42%) patients, and high stages III to IV by 196 (58%). Curative surgery was performed on 176 (52%) patients. Survival data were obtained from the national registers. Slides from archive tissue blocks were prepared for immunohistochemistry by use of COX-2, human antigen R (HuR), cyclin A, matrix metalloproteinases 2 and 9 (MMP-2, MMP-9), and Ki-67 antibodies. Immunostainings were scored by microscopy, and scores were entered into a database. Associations of tumor markers with clinicopathological factors were calculated, as well as associations with p53, p21, and results of flow cytometry from earlier studies. Survival analysis was performed by the Kaplan-Meier method, and Cox multivariate models were reconstructed. Cell culture experiments were performed to explore the effect of small interfering (si)RNA of HuR on COX-2 expression in a TMK-1 gastric cancer cell line. Results: Overall 5-year survival was 35.1%. Study I showed that COX-2 was an independent prognostic factor, and that the prognostic impact of COX-2 was more pronounced in low-stage patients. Cytoplasmic HuR expression also associated with reduced survival in gastric cancer patients in a non-independent manner. Cell culture experiments showed that HuR can regulate COX-2 expression in TMK-1 cells in vitro, with an association also between COX-2 and HuR tissue expression in a clinical material. In Study II, cyclin A was an independent prognostic factor and was associated with HuR expression in the gastric cancer material. The results of Study III showed that epithelial MMP-2 associated with survival in univariate, but not in multivariate analysis. However, MMP-9 showed no prognostic value. MMP-2 expression was associated with COX-2 expression. In Study IV, the prognostic power of COX-2 was compared with that of all tested markers associated with survival in Studies I to III, as well as with p21, p53, and flow cytometry results. COX-2 and p53 were independent prognostic factors, and COX-2 expression was associated with that of p53 and Ki-67 and also with aneuploidy. Conclusions: COX-2 is an independent prognostic factor in gastric cancer, and its prognostic power emerges especially in low stage cancer. COX-2 is regulated by HuR, and is associated with factors reflecting invasion, proliferation, and apoptosis. In an extended multivariate model, COX-2 retained its position as an independent prognosticator. COX-2 can be considered a promising new prognostic marker in gastric cancer.
  • Juuti, Anne (Helsingin yliopisto, 2006)
    Background. Pancreatic cancer is one of the major causes of cancer death in the industrialised world. The overall survival of patients with ductal pancreatic adenocarcinoma is poor: 5-year survival is only 0.2 to 4%. Tumour stage and histological grade are used as prognostic markers in pancreatic cancer. However, there are differences in survival within stages and histological grades. New, additional and more accurate prognostic tools are needed. Aims. The purpose of this study was to investigate whether the tissue expression of potential and promising tumour markers p27, tenascin C, syndecan-1, COX-2 and MMP-2 are associated with clinicopathological parameters in pancreatic cancer. The expression of p27, tenascin C and syndecan-1 was also evaluated in acute and chronic pancreatitis. The main purpose in the study was to find new prognostic markers for pancreatic adenocarcinoma. Patients. The study included 147 patients with histologically verified pancreatic adenocarcinoma treated at Helsinki University Central Hospital from 1974 to1998. Methods. The expression of tumour marker antigens was demonstrated by immunohistochemistry using monoclonal antibodies against p27, syndecan-1, tenascin C, COX-2 and MMP-2. The results were compared with clinicopathological variables, i.e. age, sex, TNM stage and histological grade. Survival analyses were performed with univariate Kaplan-Meier life-tables and the log-rank test, while multivariate analyses were performed using Cox regression. Results. Pancreatic adenocarcinomas expressed p27, syndecan-1, tenascin C, COX-2 and MMP-2 in 30, 94, 92, 36 and 50% of the samples, respectively. Loss of p27 expression was associated with poor prognosis in stage I and II pancreatic cancer. Stromal syndecan-1 expression was an independent prognostic marker in pancreatic cancer, whereas epithelial syndecan-1 expression predicted better prognosis only in stage I and II disease. Tenascin C expression did not correlate with survival but was associated with differentiation. COX-2 expression was associated with poor outcome and was an independent prognostic factor. Epithelial MMP-2 correlated with poor prognosis in pancreatic cancer. Conclusion: p27 and epithelial syndecan-1 are prognostic markers in early (stage I and II) pancreatic cancer. Stromal syndecan-1, COX-2 and epithelial MMP-2 are prognostic factors in ductal pancreatic adenocarcinoma.
  • Tynninen, Olli (Helsingin yliopisto, 2011)
    Gliomas are the most frequent primary brain tumours. The cardinal features of gliomas are infiltrative growth pattern and progression from low-grade tumours to a more malignant phenotype. These features of gliomas generally prevent their complete surgical excision and cause their inherent tendency to recur after initial treatment and lead to poor long-term prognosis. Increasing knowledge about the molecular biology of gliomas has produced new markers that supplement histopathological diagnostics. Molecular markers are also used to evaluate the prognosis and predict therapeutic response. The purpose of this thesis is to study molecular events involved in the malignant progression of gliomas. Gliomas are highly vascularised tumours. Contrast enhancement in magnetic resonance imaging (MRI) reflects a disrupted blood-brain barrier and is often seen in malignant gliomas. In this thesis, 62 astrocytomas, oligodendrogliomas and oligoastrocytomas were studied by MRI and immunohistochemistry. Contrast enhancement in preoperative MRI was associated with angiogenesis, tumour cell proliferation and histological grade of gliomas. Activation of oncogenes by gene amplification is a common genetic aberration in gliomas. EGFR amplification on chromosome 7p12 occurs in 30-40% of glioblastomas. PDGFRA, KIT and VEGFR2 are receptor tyrosine kinase genes located on chromosome 4q12. Amplification of these genes was studied using in situ hybridisation in the primary and recurrent astrocytomas, oligodendrogliomas and oligoastrocytomas of 87 patients. PDGFRA, KIT or VEGFR2 amplification was found in 22% of primary tumours and 36% of recurrent tumours including low-grade and malignant gliomas. The most frequent aberration was KIT amplification, which occurred in 10% of primary tumours and in 27% of recurrent tumours. The expression of ezrin, cyclooxygenase 2 (COX-2) and HuR was studied immunohistochemically in a series of primary and recurrent gliomas of 113 patients. Ezrin is a cell membrane-cytoskeleton linking-protein involved in the migration of glioma cells. The COX-2 enzyme is implicated in the carcinogenesis of epithelial neoplasms and is overexpressed in gliomas. HuR is an RNA-stabilising protein, which regulates the expression of several proteins including COX-2. Ezrin, COX-2 and HuR were associated with histological grade and the overall survival of glioma patients. However, in multivariate analysis they were not independent prognostic factors. In conclusion, these results suggest that contrast enhancement in MRI can be used as a surrogate marker for the proliferative and angiogenic potential of gliomas. Aberrations of PDGFRA, KIT and VEGFR2 genes, as well as the dysregulated expression of ezrin, COX-2 and HuR proteins, are linked to the progression of gliomas.
  • Nevalainen, Martti Juha (Helsingin yliopisto, 2004)
  • Koskentausta, Terhi (Helsingin yliopisto, 2006)
    Children with intellectual disability are at increased risk for emotional and behavioural problems, but many of these disturbances fail to be diagnosed. Structured checklists have been used to supplement the psychiatric assessment of children without intellectual disability, but for children with intellectual disability, only a few checklists are available. The aim of the study was to investigate psychiatric disturbances among children with intellectual disability: the prevalence, types and risk factors of psychiatric disturbances as well as the applicability of the Finnish translations of the Developmental Behaviour Checklist (DBC-P) and the Child Behavior Checklist (CBCL) in the assessment of psychopathology. The subjects comprised 155 children with intellectual disability, and data were obtained from case records and five questionnaires completed by the parents or other carers of the child. According to case records, a psychiatric disorder had previously been diagnosed in 11% of the children. Upon careful re-examination of case records, the total proportion of children with a psychiatric disorder increased to 33%. According to checklists, the frequency of probable psychiatric disorder was 34% by the DBC-P, and 43% by the CBCL. The most common diagnoses were pervasive developmental disorders and hyperkinetic disorders. The results support previous findings that compared with children without intellectual disability, the risk of psychiatric disturbances is 2-3-fold in children with intellectual disability. The risk of psychopathology was most significantly increased by moderate intellectual disability and low socio-economic status, and decreased by adaptive behaviour, language development, and socialisation as well as living with both biological parents. The results of the study suggest that both the DBC-P and the CBCL can be used to discriminate between children with intellectual disability with and without emotional or psychiatric disturbance. The DBC-P is suitable for children with any degree of intellectual disability, and the CBCL is suitable at least for children with mild intellectual disability. Because the problems of children with intellectual disability differ somewhat from those of children without intellectual disability, checklists designed specifically for children with intellectual disability are needed.
  • 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 
  • Ahola, Aila (Helsingin yliopisto, 2012)
    Diabetes is characterized by a number of metabolic disturbances. Self-management, that aims at normalizing these disturbances, constitutes the backbone of diabetes treatment. A number of factors may affect how patients take care of themselves. Knowledge of the current treatment guidelines is not sufficient alone, but must be translated into compliance. Also various psychological determinants, such as depression, may affect how patients take care of themselves. Sense of coherence (SOC), which refers to the extent to which individuals are able to use various resources to sustain and improve health, offers another kind of an approach to the issue of diabetes management. The aim of this thesis was to investigate the adherence with dietary recommendations in patients with type 1 diabetes, and to study the association between self-reported and measured compliance with recommendations. We also investigated the relevance of the SOC in diabetes self care, patients per-ceptions of their disease, and microvascular complications. Moreover the associations between depression and the metabolic syndrome and mortality were evaluated. The thesis is part of the Finnish Diabetic Nephropathy (FinnDiane) study. Compliance with dietary guidelines was highest for the intake of protein, alcohol, and sucrose. A substantial proportion of the participants consumed less carbohydrates, and fibre than recommended. Sodium chloride and saturated fatty acid intakes frequently exceeded the recommendations. Of the micronutrients, the recommendations for vitamin D, folate and iron were most frequently unmet. Self-reported compliance with dietary recommendations was reflected in more frequently meeting the recommendations for carbohydrates, total fat, saturated fatty acids, and alcohol intakes. Despite this, the observed frequencies of meeting the actual guidelines among these patients were, for many nutrients, only modest (e.g., 55% for carbohydrates and 35% for saturated fatty acids). In women, higher SOC score (indicating stronger SOC) was associated with more prudent food choices. In men, the SOC scores were positively associated with higher level of physical activity. Weak SOC was associated with higher HbA1c levels among women. In men, weak SOC was associated with the presence of diabetic nephropathy. Four factors were formed from the diabetes questionnaire (conceptions of HbA1c, complications, diabetes control, and hypoglycaemia). Higher factor scores describing less favourable self-reports were observed for conceptions of HbA1c and hypoglycaemia among those with weak SOC. Moreover, in men, weak SOC was associated with the complications factor. In women, the metabolic syndrome was a more frequent observation among those with symptoms of depression. Of the individual components of the metabolic syndrome, the BDI score was associated with the waist and triglyceride components in women. Purchases of antidepressant agents reduced the 10-year cumulative survival, mostly so among women with such purchases at around the baseline visit. The purchasers of antidepressant agents died mostly of chronic diabetic complications, while the predominant underlying cause of death among non-purchasers were cardiovascular diseases.
  • Talala, Kirsi (Helsingin yliopisto, 2013)
    Mental health problems have shown to be highly prevalent and associated with socio-economic factors in populations worldwide. Persistent or increasing health inequalities are a common phenomenon, however, few studies have explored socioeconomic differences in mental health over time. Psychological distress refers to non-specific psychopathology, which includes symptoms such as depression, insomnia and stress. Psychological distress is prevalent (5 - 48%) and known to be associated with lower quality of life, mental and physical morbidity and mortality. Moreover, psychological distress has been proposed as one probable explanation in mediating the socio-economic gradient in health and mortality. Few studies have examined prevalence trends in psychological distress and changes in socio-economic differences in psychological distress over time, or the contribution of psychological distress to the socio-economic differences in cause-specific mortality. This study aimed to explore these topics. The database was Health Behaviour and Health among the Finnish Adult Population -survey (AVTK, 1979 - 2002) linked with Statistics Finland socio-economic register data, and the Finnish Cause of Death Register follow-up. Outcome measures for psychological distress included self-reported depression, insomnia and stress. Socio-economic status was measured by education, employment status and household income. Mortality data consisted of suicide, accidents and violence, alcohol-related causes of death and coronary heart disease mortality. The overall prevalence of psychological distress was 14 - 20%. Insomnia and stress increased among both genders, whereas depression decreased among women. Socio-economic differences were demonstrated in all psychological distress measures. High risk groups for psychological distress were the unemployed, retired respondents (<65 years) and those with no partner. Those with the lowest household incomes experienced more depression and stress. However, some of the associations were curvilinear and converse. Most notably, stress was most common among the highest educated. Socio-economic differences in psychological distress did not change substantially over time. Depression, insomnia and extremely high stress accounted for some of the socio-economic differences in unnatural but not in CHD mortality. The increase in the prevalence of insomnia and stress, and persistent socio-economic differences in psychological distress present a perceptible public health challenge. However, reversed gradients, especially in stress, should be considered in detail. Improvement of psychological distress in certain socio-economic groups may reduce some of the socio-economic differences, particularly in unnatural mortality.
  • Pirinen, Teija (Helsingin yliopisto, 2012)
    According to the literature, risk for emotional symptoms, anxiety and social dysfunction is increased among youth with inflammatory bowel disease (IBD). Previous studies in this area are, however, sparse and in those that do exist, methodological problems occur. Frequency of sleep disturbances, daytime tiredness, and psychosocial symptoms related to sleeping difficulties in paediatric IBD are so far unstudied. The current study aimed to evaluate the frequency of psychosocial symptoms and sleep problems among Finnish adolescents with paediatric IBD compared to population-based controls. Both parents and adolescents themselves were used as a source of information. The data was collected in spring 2007 as a postal questionnaire-based survey. Parents and adolescents received standardised questionnaires that measured adolescents psychosocial symptoms, competence, sleep, and daytime tiredness (Child Behavior Checklist, CBCL, for parent; Youth Self-Report, YSR, and Sleep Self-Report, SSR, for adolescent). The final study includes 160 (56%) adolescents with IBD and 236 (27%) controls with their parents. The groups of patients and controls were similar according to demographic and descriptive characteristics (gender, age, place of residence and socio-economic status), and represented the whole country well. In the first study, parent and self-reported psychosocial symptoms and competence were evaluated among adolescents with IBD in comparison to the controls, and in the patients, according to severity of IBD symptoms. The main findings here were that the patients reported equally as much psychosocial problems in self-reports as the controls did, even though their parents reported significantly more emotional symptoms, somatic complaints, social problems, thought problems, and lower competence in their children compared to the parents of controls. The frequency of psychosocial problems correlated positively with the severity of IBD symptoms according to both respondents. This study suggests that self-rated questionnaires may not be efficient enough to measure psychosocial well-being of adolescents with IBD and, thus, complementary assessments should be applied. Furthermore, psychosocial evaluation especially among patients with severe IBD symptoms should be routinely applied in clinical visits. Parental evaluation is of great value and should be included in the psychosocial assessment of adolescents with IBD. The second study assessed parent-adolescent agreement regarding emotional, behavioural and somatic symptoms in adolescents with IBD. In 5% of the cases, parents and adolescents agreed on the presence of a psychosocial problem, but in 21% of the cases they disagreed. According to both respondents, no problems existed in 74% of the cases. Altogether, the parent-adolescent agreement rate was poor to low, being lowest on anxious/depressed mood and thought problems, and highest on social problems. The parents reported significantly more often somatic symptoms close to clinical range (subclinical) in their adolescents than the adolescents themselves did. These results indicate that in patients with paediatric IBD, parents and adolescents often disagree on patient s psychosocial problems and somatic complaints. Clinically significant psychosocial and somatic problems would stay unrecognised in this patient group without asking about these symptoms from both the parents and the adolescents themselves. The third study evaluated frequency of parent and self-reported sleep problems and daytime tiredness among adolescents with IBD in relation to the controls and, in the patient group, in relation to the severity of the disease. The results revealed that, according to the parental perception, adolescents with IBD are burdened with more frequent sleep disturbances and overtiredness than the controls. However, self-reported sleep problems and daytime tiredness were equally common in both groups. Parent and self-reported sleep problems and overtiredness associated positively with the self-reported severity of IBD symptoms. Thus, especially those adolescents with IBD who suffer from severe symptoms of the disease should be further assessed for sleep disturbances and daytime tiredness. Finally, the fourth study examined parent and self-reported psychosocial symptoms and somatic complaints in sleep-troubled (n=32) versus non-sleep troubled adolescents with IBD (n=125). According to both respondents, the sleep-troubled patients had more frequent psychosocial problems (especially anxiety/depressed mood and aggressive behaviour) and somatic complaints (various aches and nausea) than their counterparts without sleep trouble. Additionally, SSR-measured sleep quality correlated significantly with parent and self-reported attention problems. These results indicate that in those adolescents with IBD who self-perceive sleeping difficulties, further assessment of psychosocial symptoms and proper evaluation of somatic symptoms is needed, as are the interventions to improve sleep quality among them.
  • Helenius, Mikko (Helsingin yliopisto, 2015)
    Irreversible vascular remodeling has a central role in a variety of pathophysiological conditions including pulmonary arterial hypertension (PAH). Hypoxia and inflammation are prominent features in PAH, along with hyperplasia and hypertrophy of vessel wall layers. Although, endothelial cell (EC) dysfunction is thought to drive the multiple forms of vascular remodeling, the origins of this phenomenon are poorly understood. Extracellular ATP and its metabolites are important regulators of vascular tone, permeability, and homeostasis. Yet little is known about their role in pathological vascular remodeling. By using chronic hypoxia and PAH animal models as well as human PAH patient samples, this study was undertaken to evaluate the catalytic activities and expression levels of nucleoside triphosphate diphosphohydrolase-1 (NTPDase1, otherwise known as CD39) and other purine-converting ectoenzymes with a primary focus on vascular EC. For this purpose we employed thin-layer chromatographic enzyme assays with 3H-labelled nucleotide substrates, in combination with various immunoassays and qPCR. In addition we have developed a highly sensitive assay for simultaneous sensing of extracellular ATP and its metabolites and also a novel method for measuring CD39 activity in modeled to in vivo conditions. In functional assays, cells or animals were stimulated through purine signaling pathways and proliferation, apoptosis, permeability, and DNA damage were assayed. Our results clearly demonstrated that the activity of CD39 was downregulated in chronic hypoxia, monocrotaline induced animal models of PAH and in human PAH patients. Attenuated enzyme activities could create a niche in the vasculature where ATP levels were increased and adenosine levels were decreased. Even a small increase in ATP concentration was enough to induce an apoptosis-resistant, hyper-proliferative, and DNA-damageresistant phenotype in ECs of pulmonary origin. The observed effects were at least partly dependent on P2Y11 receptor activation. In addition, we found that low ATP concentrations could induce pulmonary smooth muscle cell proliferation and migration. Interestingly, we found that small apelin peptide could directly restore the downregulated CD39 activity. This study implies that purinergic signaling, ATP mediated cell activation in particular, plays a truly significant role in pathological vascular remodeling, and that it could be used as a therapeutic target. Moreover, purinergic signaling pathways could be used before vascular injury to precondition EC against irradiation or chemotherapy induced DNA damage.
  • af Hällström, Taija (Helsingin yliopisto, 2007)
    Prostate cancer is the most common noncutaneous malignancy and the second leading cause of cancer mortality in men. In 2004, 5237 new cases were diagnosed and altogether 25 664 men suffered from prostate cancer in Finland (Suomen Syöpärekisteri). Although extensively investigated, we still have a very rudimentary understanding of the molecular mechanisms leading to the frequent transformation of the prostate epithelium. Prostate cancer is characterized by several unique features including the multifocal origin of tumors and extreme resistance to chemotherapy, and new treatment options are therefore urgently needed. The integrity of genomic DNA is constantly challenged by genotoxic insults. Cellular responses to DNA damage involve elegant checkpoint cascades enforcing cell cycle arrest, thus facilitating damage repair, apoptosis or cellular senescence. Cellular DNA damage triggers the activation of tumor suppressor protein p53 and Wee1 kinase which act as executors of the cellular checkpoint responses. These are essential for genomic integrity, and are activated in early stages of tumorigenesis in order to function as barriers against tumor formation. Our work establishes that the primary human prostatic epithelial cells and prostatic epithelium have unexpectedly indulgent checkpoint surveillance. This is evidenced by the absence of inhibitory Tyr15 phosphorylation on Cdk2, lack of p53 response, radioresistant DNA synthesis, lack of G1/S and G2/M phase arrest, and presence of persistent gammaH2AX damage foci. We ascribe the absence of inhibitory Tyr15 phosphorylation to low levels of Wee1A, a tyrosine kinase and negative regulator of cell cycle progression. Ectopic Wee1A kinase restored Cdk2-Tyr15 phosphorylation and efficiently rescued the ionizing radiation-induced checkpoints in the human prostatic epithelial cells. As variability in the DNA damage responses has been shown to underlie susceptibility to cancer, our results imply that a suboptimal checkpoint arrest may greatly increase the accumulation of genetic lesions in the prostate epithelia. We also show that small molecules can restore p53 function in prostatic epithelial cells and may serve as a paradigm for the development of future therapeutic agents for the treatment of prostate cancer We hypothesize that the prostate has evolved to activate the damage surveillance pathways and molecules involved in these pathways only to certain stresses in extreme circumstances. In doing so, this organ inadvertently made itself vulnerable to genotoxic stress, which may have implications in malignant transformation. Recognition of the limited activity of p53 and Wee1 in the prostate could drive mechanism-based discovery of preventative and therapeutic agents.
  • Hattula, Katarina (Helsingin yliopisto, 2007)
    Rab8 and its interacting proteins as regulators of cell polarization During the development of a multi-cellular organism, progenitor cells have to divide and migrate appropriately as well as organize their differentiation with one another, in order to produce a viable embryo. To divide, differentiate and migrate cells have to undergo polarization, a process where internal and external components such as actin, microtubules and adhesion receptors are reorganized to produce a cell that is asymmetric, with functionally different surfaces. Also in the adult organism there is a continuous need for these processes, as cells need to migrate in response to tissue damage and to fight infection. Improper regulation of cell proliferation and migration can conversely lead to disease such as cancer. GTP-binding proteins function as molecular switches by cycling between a GTP-bound (active) conformation and a GDP-bound (inactive) conformation. The Ras super-family of small GTPases are found in all eukaryotic cells. They can be functionally divided into five subfamilies. The Ras family members mainly regulate gene expression, controlling cell proliferation and differentiation. Ras was in fact the first human oncogene to be characterized, and as much as 30% of all human tumors may be directly or indirectly caused by mutations of Ras molecules The Rho family members mainly regulate cytoskeletal reorganization. Arf proteins are known to regulate vesicle budding and Rab proteins regulate vesicular transport. Ran regulates nuclear transport as well as microtubule organization during mitosis. The focus of the thesis of Katarina Hattula, is on Rab8, a small GTPase of the Rab family. Activated Rab8 has previously been shown to induce the formation of new surface extensions, reorganizing both actin and microtubules, and to have a role in directed membrane transport to cell surfaces. However, the exact membrane route it regulates has remained elusive. In the thesis three novel interactors of Rab8 are presented. Rabin8 is a Rab8-specific GEF that localizes to vesicles where it presumably recruits and activates its target Rab8. Its expression in cells leads to remodelling of actin and the formation of polarized cell surface domains. Optineurin, known to be associated with a leading cause of blindness in humans (open-angle glaucoma), is shown to interact specifically with GTP-bound Rab8. Rab8 binds to an amino-terminal region and interestingly, the Huntingtin protein binds a carboxy-terminal region of optineurin. (Aberrant Huntingtin protein is known to be the cause Huntington s disease in humans.) Co-expression of Huntingtin and optineurin enhanced the recruitment of Huntingtin to Rab8-positive vesicular structures. Furthermore, optineurin promoted cell polarization in a similar way to Rab8. A third novel interactor of Rab8 presented in this thesis is JFC1, a member of the synaptogamin-like protein (Slp) family. JFC1 interacts with Rab8 specifically in its GTP-bound form, co-localizes with endogenous Rab8 on tubular and vesicular structures, and is probably involved in controlling Rab8 membrane dynamics. Rab8 is in this thesis work clearly shown to have a strong effect on cell shape. Blocking Rab8 activity by expression of Rab8 RNAi, or by expressing the dominant negative Rab8 (T22N) mutant leads to loss of cell polarity. Conversely, cells expressing the constitutively active Rab8 (Q67L) mutant exhibit a strongly polarized phenotype. Experiments in live cells show that Rab8 is associated with macropinosomes generated at ruffling areas of the membrane. These macropinosomes fuse with or transform into tubules that move toward the cell centre, from where they are recycled back to the leading edge to participate in protrusion formation. The biogenesis of these tubules is shown to be dependent on both actin and microtubule dynamics. The Rab8-specific membrane route studied contained several markers known to be internalized and recycled (1 integrin, transferrin, transferrin receptor, cholera toxin B subunit (CTxB), and major histocompatibility complex class I protein (MHCI)). Co-expression studies revealed that Rab8 localization overlaps with that of Rab11 and Arf6. Rab8 is furthermore clearly functionally linked to Arf6. The data presented in this thesis strongly suggests a role for Rab8 as a regulator for a recycling compartment, which is involved in providing structural and regulatory components to the leading edge to participate in protrusion formation.
  • Kotaniemi-Talonen, Laura (Helsingin yliopisto, 2009)
    A randomised and population-based screening design with new technologies has been applied to the organised cervical cancer screening programme in Finland. In this experiment the women invited to routine five-yearly screening are individually randomised to be screened with automation-assisted cytology, human papillomavirus (HPV) test or conventional cytology. By using the randomised design, the ultimate aim is to assess and compare the long-term outcomes of the different screening regimens. The primary aim of the current study was to evaluate, based on the material collected during the implementation phase of the Finnish randomised screening experiment, the cross-sectional performance and validity of automation-assisted cytology (Papnet system) and primary HPV DNA testing (Hybrid Capture II assay for 13 oncogenic HPV types) within service screening, in comparison to conventional cytology. The parameters of interest were test positivity rate, histological detection rate, relative sensitivity, relative specificity and positive predictive value. Also, the effect of variation in performance by screening laboratory on age-adjusted cervical cancer incidence was assessed. Based on the cross-sectional results, almost no differences were observed in the performance of conventional and automation-assisted screening. Instead, primary HPV screening found 58% (95% confidence interval 19-109%) more cervical lesions than conventional screening. However, this was mainly due to overrepresentation of mild- and moderate-grade lesions and, thus, is likely to result in overtreatment since a great deal of these lesions would never progress to invasive cancer. Primary screening with an HPV DNA test alone caused substantial loss in specificity in comparison to cytological screening. With the use of cytology triage test, the specificity of HPV screening improved close to the level of conventional cytology. The specificity of primary HPV screening was also increased by increasing the test positivity cutoff from the level recommended for clinical use, but the increase was more modest than the one gained with the use of cytology triage. The performance of the cervical cancer screening programme varied widely between the screening laboratories, but the variation in overall programme effectiveness between respective populations was more marginal from the very beginning of the organised screening activity. Thus, conclusive interpretations on the quality or success of screening should not be based on performance parameters only. In the evaluation of cervical cancer screening the outcome should be selected as closely as possible to the true measure of programme effectiveness, which is the number of invasive cervical cancers and subsequent deaths prevented in the target population. The evaluation of benefits and adverse effects of each new suggested screening technology should be performed before the technology becomes an accepted routine in the existing screening programme. At best, the evaluation is performed randomised, within the population and screening programme in question, which makes the results directly applicable to routine use.