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  • 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.
  • Pietiläinen, Olli (Helsingin yliopisto, 2014)
    Severe mental disorders including schizophrenia often segregate within the same families. Twin and family studies suggest that this co-occurrence is largely genetic, which implies that the different mental disorders have a shared genetic background. Some symptomatic features, such as cognitive impairment also manifest to a variable degree in the majority of severe mental disorders. Cognitive impairment occurs already before the onset of the disease and healthy family members of patients perform worse in cognitive tests than do the general population, which suggests that the cognitive impairment is indicative of genetic loading of the disease. Furthermore, the cognitive impairment persists throughout the disease and is associated with poorer outcome. This led us to hypothesize that the genetic architecture of schizophrenia is more similar to developmental disorders than had been considered earlier. Specifically, we hypothesized that rare high impact genetic variants play a role in the genetic risk for schizophrenia. Rare recurrent large-scale structural variation has long known to cause developmental syndromes, such as Prader-Willi syndrome or Velocardiofacial syndrome. In this study we investigated the role of large-scale chromosomal copy number variants in the genetic background of schizophrenia and other traits hypothesized to reflect abnormal neuronal development. In this study four chromosomal deletions on 1q21, 15q11.2, 15q13.3 and 22q11.2 were identified to be associated with schizophrenia. Three of the deletions occurred recurrently, whereas the deletion on 22q11.22 was a founder mutation enriched especially in the North-East region of Finland. On a population level, carriers of large deletions were found to have more intellectual disability or sub-normality (IQ<85) than non-carriers. Also milder learning difficulties as measured by repeated grades in school were more common among carriers of large deletions. The four deletions specifically identified as associating with schizophrenia are linked to variable phenotypes with the strongest effect manifesting in intellectual disabilities. The regional enrichment of the deletion on 22q11.22 also enabled the assessment of recessive effects related to the deletion. Four individuals, all presenting with a neurodevelopmental phenotype and/or schizophrenia, were identified as homozygous for the deletion. This deletion overlaps one gene encoding for topoisomerase 3 beta (TOP3β) that forms a protein complex with FMRP, the fragile X mental retardation protein, via tudor domain containing 3 (TDRD3) protein. The results of this study imply that rare high risk variants are present in a sub set of schizophrenia patients and that these variants are shared with developmental disorders. The study also demonstrates that special populations such as population isolates can provide useful study designs in identifying rare genetic risk variants, especially with recessive effects for complex traits.
  • Ylösmäki, Erkko (Helsingin yliopisto, 2013)
    MicroRNAs (miRNAs) are small noncoding RNA molecules that have important regulatory roles in a wide range of biological processes. miRNAs are often expressed in a tissue- and/or differentiation state-specific patterns, and it is estimated that miRNAs can regulate the expression of more than 50% of all human genes. We have exploited these tissue-specific miRNA expression patterns in the modification of viral replicative tropism. In order to engineer the replicative tropism of oncolytic adenoviruses, we developed a recombinant adenovirus that in the 3 UTR of the critical E1A gene contains sequences complementary to the liver-specific miRNA miR122. This allowed us to generate a novel recombinant adenovirus that was severely attenuated in human liver, but replicated to high titres in colorectal cancer. Systemic injection of miR122-targeted adenovirus into mice did not induce liver toxicity. In a human lung cancer xenograft mouse model this miR122-targeted adenovirus showed potent antitumour activity. We also studied the possibility to exploit neuron-specific miRNA expression patterns in the modification of tissue tropism of an alphavirus Semliki Forest virus (SFV). We engineered SFV genome to contain sequences complementary to the neuron-specific miRNA miR124. In vitro characterization of this novel virus showed that the modification of the SFV genome per se did not affect polyprotein processing or oncolytic potency. Intraperitoneally administered miR124-targeted SFV displayed an attenuated spread into the central nervous system (CNS) and increased survival of infected mice. Also, mice pre-infected with miR124-targeted SFV elicited strong protective immunity against otherwise lethal challenge with a highly virulent wild-type SFV strain. In conclusion, these results show that miRNA-targeting is a potent new strategy to engineer viral tropism in development of safer and more efficient reagents for virotherapy applications.
  • Järveläinen, Juha (Helsingin yliopisto, 2005)
  • Puputti, Marjut (Helsingin yliopisto, 2012)
    In the present study we investigated expression and amplification of KIT, PDGFRA, VEGFR2 and EGFR in glioblastomas and in lower grade gliomas, and analyzed the hot spot mutation sites of KIT, PDGFRA and EGFR genes for presence of mutations in glioblastoma. Furthermore, we evaluated expression of KIT, SCF and VEGFR2 in paediatric brain tumors and in tumour endothelial cells, and studied the intratumoral heterogeneity of EGFR and KIT amplifications in primary glioblastomas and astrocytomas. Mutations turned out to be infrequent in these genes suggesting that neither primary nor secondary glioblastomas are usually driven by KIT or PDGFRA mutations, or by EGFR kinase domain mutations. Amplifications of KIT, VEGFR2, PDGFRA and EGFR turned out to be frequent in glioblastoma. KIT was amplified in 47% and VEGFR2 in 39% out of the 43 primary glioblastomas investigated, and PDGFRA in 29%. Presence of KIT, PDGFRA and VEGFR2 amplifications were strongly associated (p < 0.0001 for each pair wise comparison) suggesting co-amplification. We investigated presence of gene amplifications also in other types of gliomas either in tumour samples collected at the time of the diagnosis or in samples collected at the time of tumour recurrence. In tumour tissue samples collected at the time of the diagnosis KIT and PDGFRA amplifications turned out to be more frequent in anaplastic astrocytomas than in astrocytomas, oligodendrogliomas and oligoastrocytomas. Amplified KIT was more frequently present in recurrent gliomas than in newly diagnosed. Pilocytic astrocytomas studied did not harbour amplification of KIT. KIT expression was common in tumour endothelial cells in pilocytic astrocytomas, and endothelial cell KIT was frequently activated. Tumour endothelial cell KIT expression was associated with a young age at the time of the diagnosis. Ependymomas also frequently expressed KIT in endothelial cells, and its expression tended to be associated with a young age at the time of the diagnosis. Finally, we investigated heterogeneity of KIT and EGFR amplification and their protein products in gliomas by studying several tissue blocks from each tumour. EGFR amplification was found in ten out of the 15 glioblastomas studied when analysis was carried out from only one tissue block, and in 11 cases when all available tissue blocks were analyzed. KIT was amplified in six out of the 15 index glioblastoma tissue blocks, but in 10 glioblastomas when all tissue blocks were analyzed. These findings suggest that glioblastomas show marked heterogeneity in KIT amplifications and that heterogeneity is less for EGFR amplifications.
  • Mantere, Outi (Helsingin yliopisto, 2007)
    This study is part of an ongoing collaborative bipolar research project, the Jorvi Bipolar Study (JoBS). The JoBS is run by the Department of Mental Health and Alcohol Research of the National Public Health Institute, Helsinki, and the Department of Psychiatry, Jorvi Hospital, Helsinki University Central Hospital (HUCH), Espoo, Finland. It is a prospective, naturalistic cohort study of secondary level care psychiatric in- and outpatients with a new episode of bipolar disorder (BD). The second report also included 269 major depressive disorder (MDD) patients from the Vantaa Depression Study (VDS). The VDS was carried out in collaboration with the Department of Psychiatry of the Peijas Medical Care District. Using the Mood Disorder Questionnaire (MDQ), all in- and outpatients at the Department of Psychiatry at Jorvi Hospital who currently had a possible new phase of DSM-IV BD were sought. Altogether, 1630 psychiatric patients were screened, and 490 were interviewed using a semistructured interview (SCID-I/P). The patients included in the cohort (n=191) had at intake a current phase of BD. The patients were evaluated at intake and at 6- and 18-month interviews. Based on this study, BD is poorly recognized even in psychiatric settings. Of the BD patients with acute worsening of illness, 39% had never been correctly diagnosed. The classic presentations of BD with hospitalizations, manic episodes, and psychotic symptoms lead clinicians to correct diagnosis of BD I in psychiatric care. Time of follow-up elapsed in psychiatric care, but none of the clinical features, seemed to explain correct diagnosis of BD II, suggesting reliance on cross- sectional presentation of illness. Even though BD II was clearly less often correctly diagnosed than BD I, few other differences between the two types of BD were detected. BD I and II patients appeared to differ little in terms of clinical picture or comorbidity, and the prevalence of psychiatric comorbidity was strongly related to the current illness phase in both types. At the same time, the difference in outcome was clear. BD II patients spent about 40% more time depressed than BD I patients. Patterns of psychiatric comorbidity of BD and MDD differed somewhat qualitatively. Overall, MDD patients were likely to have more anxiety disorders and cluster A personality disorders, and bipolar patients to have more cluster B personality disorders. The adverse consequences of missing or delayed diagnosis are potentially serious. Thus, these findings strongly support the value of screening for BD in psychiatric settings, especially among the major depressive patients. Nevertheless, the diagnosis must be based on a clinical interview and follow-up of mood. Comorbidity, present in 59% of bipolar patients in a current phase, needs concomitant evaluation, follow-up, and treatment. To improve outcome in BD, treatment of bipolar depression is a major challenge for clinicians.
  • Natah, Sirajedin Sabri (Helsingin yliopisto, 2001)
  • Ilmarinen, Taru (Helsingin yliopisto, 2013)
    Some manifestations of human papillomavirus (HPV) infection are indolent and self-limiting, while others cause considerable morbidity. In recurrent respiratory papillomatosis (RRP), low-risk HPV types within the respiratory tract cause wart-like lesions, typically on vocal folds. The most common symptom is hoarseness, but stridor may also occur due to airway obstruction. In a minority of patients, the disease becomes aggressive and may undergo malignant transformation. Medical records were reviewed from all patients (n=32) treated for juvenile-onset recurrent respiratory papillomatosis (JORRP) between 1975 and 1994 at Helsinki University Hospital. Eighteen patients participated in a study assessing the effect of JORRP on adult voice quality and health-related quality of life (HRQOL). Compared to age- and gender-matched controls with similar smoking habits, the quality of voice in these adult patients with a history of JORRP was significantly lower in both acoustic and perceptual analyses. Significant differences emerged neither in HRQOL, nor in subjective voice-related handicap. Despite the viral etiology, treatment of RRP is based on surgery. Patients with frequently relapsing or otherwise aggressive disease may benefit from adjuvant medical therapies, such as local injections of cidofovir. Cidofovir is an antiviral medicine officially indicated for intravenous treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS). Its intravenous administration has caused nephrotoxic side-effects and neutropenia. Animal studies have raised suspicions of its carcinogenicity. According to its manufacturer, patients treated either by off-label indications, or by an unapproved route of administration (intraocular or topical) have developed severe side-effects. An international multicenter study collected data from 635 RRP patients, 275 of which were treated with cidofovir. Mean follow-up after the first cidofovir injection was 3.3 years. Differences in incidence of upper respiratory tract and tracheal malignancies were non-significant between patients treated with and without cidofovir. After local administration of cidofovir, no clinical evidence emerged for nephrotoxicity or neutropenia. Between 1975 and 2011, a total of 324 RRP patients underwent treatment at Helsinki University Hospital for laryngeal papillomas (LPs). Nine patients (2.8%) developed laryngeal squamous cell carcinoma (SCC). Expression of toll-like receptors (TLRs) 2, 4, and 9 were analyzed in laryngeal tissue specimens from these patients by immunohistochemistry (IHC). Controls were 9 RRP patients without malignant transformation, 23 patients clinically presenting with chronic laryngitis, and 19 laryngeal SCC patients without pre-existing RRP. Compared to specimens from those with chronic laryngitis and laryngeal SCC, expression of cytoplasmic TLR4 and TLR9 was significantly lower in LPs. Nuclear TLR4 staining was significantly lower in LPs undergoing transformation into laryngeal SCC, than in LPs without malignant conversion. In laryngeal SCCs, high cytoplasmic staining for TLR4 was associated with higher grade and advanced T stage. HPV infections are spread through direct contact from skin or mucosa during sexual contact, and from mother to child during labor. Five RRP patients and five patients with genital warts participated with six physicians and twelve nurses in a study investigating transmission of HPV from patients to the oral mucosa and surgical gloves and masks of health care personnel during carbon dioxide (CO2) laser treatment. HPV deoxyribonucleic acid (DNA) was detected by polymerase chain reaction (PCR) on the surgical gloves, but not on the surgical masks or oral mucosa of health care personnel. Provided that protection is sufficient during CO2 laser treatment, the risk for HPV transmission to health care personnel seems low.
  • Laitinen, Arja (Helsingin yliopisto, 2009)
    The purpose of this study was to estimate the prevalence and distribution of reduced visual acuity, major chronic eye diseases, and subsequent need for eye care services in the Finnish adult population comprising persons aged 30 years and older. In addition, we analyzed the effect of decreased vision on functioning and need for assistance using the World Health Organization’s (WHO) International Classification of Functioning, Disability, and Health (ICF) as a framework. The study was based on the Health 2000 health examination survey, a nationally representative population-based comprehensive survey of health and functional capacity carried out in 2000 to 2001 in Finland. The study sample representing the Finnish population aged 30 years and older was drawn by a two-stage stratified cluster sampling. The Health 2000 survey included a home interview and a comprehensive health examination conducted at a nearby screening center. If the invited participants did not attend, an abridged examination was conducted at home or in an institution. Based on our finding in participants, the great majority (96%) of Finnish adults had at least moderate visual acuity (VA ≥ 0.5) with current refraction correction, if any. However, in the age group 75–84 years the prevalence decreased to 81%, and after 85 years to 46%. In the population aged 30 years and older, the prevalence of habitual visual impairment (VA ≤ 0.25) was 1.6%, and 0.5% were blind (VA < 0.1). The prevalence of visual impairment increased significantly with age (p < 0.001), and after the age of 65 years the increase was sharp. Visual impairment was equally common for both sexes (OR 1.20, 95% CI 0.82 – 1.74). Based on self-reported and/or register-based data, the estimated total prevalences of cataract, glaucoma, age-related maculopathy (ARM), and diabetic retinopathy (DR) in the study population were 10%, 5%, 4%, and 1%, respectively. The prevalence of all of these chronic eye diseases increased with age (p < 0.001). Cataract and glaucoma were more common in women than in men (OR 1.55, 95% CI 1.26 – 1.91 and OR 1.57, 95% CI 1.24 – 1.98, respectively). The most prevalent eye diseases in people with visual impairment (VA ≤ 0.25) were ARM (37%), unoperated cataract (27%), glaucoma (22%), and DR (7%). One-half (58%) of visually impaired people had had a vision examination during the past five years, and 79% had received some vision rehabilitation services, mainly in the form of spectacles (70%). Only one-third (31%) had received formal low vision rehabilitation (i.e., fitting of low vision aids, receiving patient education, training for orientation and mobility, training for activities of daily living (ADL), or consultation with a social worker). People with low vision (VA 0.1 – 0.25) were less likely to have received formal low vision rehabilitation, magnifying glasses, or other low vision aids than blind people (VA < 0.1). Furthermore, low cognitive capacity and living in an institution were associated with limited use of vision rehabilitation services. Of the visually impaired living in the community, 71% reported a need for assistance and 24% had an unmet need for assistance in everyday activities. Prevalence of ADL, instrumental activities of daily living (IADL), and mobility increased with decreasing VA (p < 0.001). Visually impaired persons (VA ≤ 0.25) were four times more likely to have ADL disabilities than those with good VA (VA ≥ 0.8) after adjustment for sociodemographic and behavioral factors and chronic conditions (OR 4.36, 95% CI 2.44 – 7.78). Limitations in IADL and measured mobility were five times as likely (OR 4.82, 95% CI 2.38 – 9.76 and OR 5.37, 95% CI 2.44 – 7.78, respectively) and self-reported mobility limitations were three times as likely (OR 3.07, 95% CI 1.67 – 9.63) as in persons with good VA. The high prevalence of age-related eye diseases and subsequent visual impairment in the fastest growing segment of the population will result in a substantial increase in the demand for eye care services in the future. Many of the visually impaired, especially older persons with decreased cognitive capacity or living in an institution, have not had a recent vision examination and lack adequate low vision rehabilitation. This highlights the need for regular evaluation of visual function in the elderly and an active dissemination of information about rehabilitation services. Decreased VA is strongly associated with functional limitations, and even a slight decrease in VA was found to be associated with limited functioning. Thus, continuous efforts are needed to identify and treat eye diseases to maintain patients’ quality of life and to alleviate the social and economic burden of serious eye diseases.
  • Vuori-Heikkilä, Elisa (Helsingin yliopisto, 2010)
    In anisometropia, the two eyes have unequal refractive power. Anisometropia is a risk factor for amblyopia. The visual deficiencies are thought to be irreversible after the first decade of life. There is, however, accumulating evidence that neural plasticity exists also in adult brains. The aim of this study was to investigate functional outcome of excimer laser refractive surgery in adult anisometropic and visually impaired patients. Additional goal was to examine changes in the primary visual cortex (V1) using multifocal functional magnetic resonance imaging (mffMRI) after laser refractive surgery. Study I comprised of 57 anisometropic patients (anisometropia of ≥3.25 diopters) and 174 isometropic myopic subjects formed the control group. A significant improvement in best-spectacle-corrected visual acuity (BSCVA) among myopic control subjects was evident 3 months postoperatively. The improvement in BSCVA was significantly slower for anisometropic patients and the improvement appeared to persist to the end of the follow-up (24 months). In study II we found that refractive surgery may be also successfully used for iathrogenic anisometropia. In Study III we evaluated mildly visually impaired adult patients after refractive surgery. There was a statistically significant improvement in BSCVA among visually impaired patients and the difference in the mean BSCVA between visually impaired patients and isometropic myopic control subjects diminished during follow-up. Study IV was a prospective follow-up trial examining the changes in the primary visual cortex after refractive surgery. Two anisometropic patients and two isometropic myopic patients were examined with a 61-region mffMRI before refractive surgery and at three, six, nine and twelve months postoperatively. In this study, a dramatic decrease in the number of active voxels in the fovea was found among anisometropic patients. The results presented in this thesis revealed that refractive surgery may be successfully used for the treatment of anisometropic adults with both congenital and iatrogenic anisometropia and for mildly visually impaired adults. The findings in conclusion strengthen our hypothesis of plastic changes in the visual cortex of adult anisometropic and mildly visually impaired patients after refractive surgery.
  • Maille, Kukka (Helsingin yliopisto, 2012)
    Inflammatory bowel diseases (IBD) and cancers of the gastrointestinal (GI) tract cause considerable morbidity and mortality. In order to enhance the diagnostics and therapeutic measures, the biology of these diseases needs to be better understood. Cellular targets and biomarkers are needed to identify subgroups of patients that are likely to respond to the treatments. This study concentrates on a novel potential biomarker. Its significance for the biology of the normal GI tract, the IBDs, the cancers of the GI tract and neuroendocrine tumors (NET) is studied. IBD cDNA expression libraries were screened to detect potential diagnostic, prognostic or predictive markers and/or targets for therapeutic intervention. A previously unknown gene, later named Reg IV, was identified. The gene was selected for characterization because of its restricted expression pattern and its upregulated expression in IBDs and in colorectal cancer (CRC). DNA cloning techniques, Western, Southern, and Northern blot techniques, cell culture, gene transfection, in situ hybridization, immunohistochemistry, and immunofluorescence were used to characterize Reg IV. Reg IV protein is a 17 kD secreted C-type lectin that belongs to the Reg protein family of known mitogens and/or antiapoptotic factors. It is physiologically expressed in enteroendocrine cells (EEC) and in proliferating goblet cells. It is expressed to a lesser extent in pancreas, stomach, prostate and testes. In EECs, it is co-expressed with serotonin and substance P, and partially co-expressed with somatostatin, ghrelin, PYY, GLP-1, GLP-2, and secretin. Interestingly, co-expression with somatostatin and ghrelin occurs only in colon and appendix, but not in the small intestine, which suggests different functions for EECs of the small intestine and colon. Reg IV protein expression was upregulated in the intestinal epithelium during inflammation and regeneration, i.e. in goblet cells of intestinal metaplasia, in proliferating margins of stomach ulcers, and in IBDs, so it can be considered a marker of reactive , proliferating goblet cells. Reg IV expression was upregulated in many mucinous and neuroendocrine tumors (NET). Strong expression was noted in mucinous cystadenoma of the appendix and pseudomyxoma peritonei. Reg IV expression in these tumors coincided partially with CDX2, MUC2, MUC5AC, and MUC6, but no regulatory correlation was found. Reg IV was also upregulated in NETs of small intestine, appendix, colon, lung, parathyroid, skin, and, more rarely, of pancreas. Co-expression with the intestinal transcription factor Hath1 was studied in normal gut epithelium and in the NETs, but no regulatory correlation was found. In ileal NET, a spatial correlation in with CD138, c-met, bFGF and HGF was found, supporting the existing data on the role of Reg IV in EGFR signaling and cell proliferation. Reg IV was thus found to be a novel member of the Reg protein family, an intestinal protein, and a putative mitogen. The regulation of its expression and its exact mechanisms of action still remain to be elucidated. Based on its expression pattern, Reg IV might have a role in maintaining the integrity of the epithelial lining of the GI tract, in the proliferation of goblet cells, and in the development of certain types of GI cancer, i.e., CRC, PMP and NETs. Further investigation is needed to confirm its value as a therapeutic target and/or prognostic or predictive biomarker.
  • Parviainen, Helka (Helsingin yliopisto, 2011)
    Transcription factors play a key role in tumor development, in which dysfunction of genes regulating tissue growth and differentiation is a central phenomenon. The GATA family of transcription factors consists of six members that bind to a consensus DNA sequence (A/T)GATA(A/G) in gene promoters and enhancers. The two GATA factors expressed in the adrenal cortex are GATA-4 and GATA-6. In both mice and humans, GATA-4 can be detected only during the fetal period, whereas GATA-6 expression is abundant both throughout development and in the adult. It is already established that GATA factors are important in both normal development and tumorigenesis of several endocrine organs, and expression of GATA-4 and GATA-6 is detected in adrenocortical tumors. The aim of this study was to elucidate the function of these factors in adrenocortical tumor growth. In embryonal development, the adrenocortical cells arise and differentiate from a common pool with gonadal steroidogenic cells, the urogenital ridge. As the adult adrenal cortex undergoes constant renewal, it is hypothesized that undifferentiated adrenocortical progenitor cells reside adjacent to the adrenal capsule and give rise to daughter cells that differentiate and migrate centripetally. A diverse array of hormones controls the differentiation, growth and survival of steroidogenic cells in the adrenal gland and the gonads. Factors such as luteinizing hormone and inhibins, traditionally associated with gonadal steroidogenic cells, can also influence the function of adrenocortical cells in physiological and pathophysiological states. Certain inbred strains of mice develop subcapsular adrenocortical tumors in response to gonadectomy. In this study, we found that these tumors express GATA-4, normally absent from the adult adrenal cortex, while GATA-6 expression is downregulated. Gonadal markers such as luteinizing hormone receptor, anti-Müllerian hormone and P450c17 are also expressed in the neoplastic cells, and the tumors produce gonadal hormones. The tumor cells have lost the expression of melanocortin-2 receptor and the CYP enzymes necessary for the synthesis of corticosterone and aldosterone. By way of xenograft studies utilizing NU/J nude mice, we confirmed that chronic gonadotropin elevation is sufficient to induce adrenocortical tumorigenesis in susceptible inbred strains. Collectively, these studies suggest that subcapsular adrenocortical progenitor cells can, under certain conditions, adopt a gonadal fate. We studied the molecular mechanisms involved in gene regulation in endocrine cells in order to elucidate the role of GATA factors in endocrine tissues. Ovarian granulosa cells express both GATA-4 and GATA-6, and the TGF-β signaling pathway is active in these cells. Inhibin-α is both a target gene for, and an atypical or antagonistic member of the TGF-β growth factor superfamily. In this study, we show that GATA-4 is required for TGF-β-mediated inhibin-α promoter activation in granulosa cells, and that GATA-4 physically interacts with Smad3, a TGF-β downstream protein. Apart from the regulation of steroidogenesis and other events in normal tissues, TGF-β signaling is implicated in tumors of multiple organs, including the adrenal cortex. Another signaling pathway found often to be aberrantly active in adrenocortical tumors is the Wnt pathway. As both of these pathways regulate the expression of inhibin-α, a transcriptional target for GATA-4 and GATA-6, we wanted to investigate whether GATA factors are associated with the components of these signaling cascades in human adrenocortical tumors. We found that the expression of Wnt co-receptors LRP5 and LRP6, Smad3, GATA-6 and SF-1 was diminished in adrenocortical carcinomas with poor outcome. All of these factors drive inhibin-α expression, and their expression in adrenocortical tumors correlated with that of inhibin-α. The results support a tumor suppressor role previously suggested for inhibin-α in the mouse adrenal cortex, and offer putative pathways associated with adrenocortical tumor aggressiveness. Unraveling the role of GATA factors and associated molecules in human and mouse adrenocortical tumors could ultimately contribute to the development of diagnostic tools and future therapies for these diseases.
  • Pietarinen-Runtti, Petra (Helsingin yliopisto, 2000)
  • Myllärniemi, Marjukka (Helsingin yliopisto, 1999)
  • Erkkilä, Krista (Helsingin yliopisto, 2002)