Background: The genes coding for human (h) chorionic somatomammotropin (CS), hCS-A and hCS-B, and placental growth hormone (GH-V), hGH-V are located at a single locus on chromosome 17q22-24. Local regulatory (5´ P and 3´ enhancer) sequences and a remote locus control region (LCR) containing a placenta-specific hypersensitive site (HS) IV, have been implicated in the efficient expression of the placental hCS/GH-V genes, in part through gene transfer studies in placental and non-placental tumor cell lines. However, low levels of endogenous expression are reported in placental tumor cells compared to normal term placenta. Thus it was hypothesized that the hCS/GH-V chromatin structure in human choriocarcinoma cells is less accessible to regulatory regions essential for efficient expression due to DNA and/or histone modifications, specifically methylation and acetylation, respectively. Approach: To assess individual hCS-A, hCS-B and hGH-V gene expression in placental and non-placental tumor cells, and assess the effect of increasing “chromatin accessibility” on hCS/GH-V RNA levels by inhibiting DNA methylation and histone deacetylation using 5-aza-2´-deoxycytidine (azadC) and trichostatin A (TSA). Principal Findings: Low levels of hCS-A, hCS-B and hGH-V RNA were detected in placental and non-placental tumor cells compared to term placenta. A significant >5-fold increase in promoter activity was seen in placental but not non-placental cells transfected with hybrid hCS promoter luciferase genes containing 3´-enhancer sequences. Placental JEG-3 cells pretreated with azadC and TSA resulted in a significant >10-fold increase in hCS-A, hCS-B and hGH-V RNA levels compared to TSA treatment alone, however, a modest ~3-fold effect was seen in non-placental MCF-7 cells. By contrast to the effect of pretreatment with azadC, post-treatment with azadC mutes the stimulatory effects of TSA on hCS/GH-V transcripts. The specificity of the response suggests that azadC treatment, and presumably hypomethylation of DNA, results in an increase in response to TSA and histone hyperacetylation at the hGH/CS locus. An assessment of histone H3/H4 hyperacetylation in JEG-3 cells treated with azadC and TSA versus TSA alone revealed significant increases consistent with a more open chromatin structure including the hCS 3´-enhancer sequences and LCR. Conclusions: These observations suggest that accessibility of remote and local regulatory regions required for efficient placental hGH/CS expression can be restricted by DNA methylation and histone acetylation status. This includes restricting access of the hCS 3´-enhancer sequences to available placental enhancer transcription factors. / May 2016

Background: The aim of this thesis was to study the relationship of pre-diagnostic circulating concentrations of sex steroid hormones (androgens, estradiol, 17-hydroxyprogesterone, and progesterone), growth factors (insulin-like growth factor-I (IGF-I), placental growth hormone (GH)), sex hormone binding globulin (SHBG), and anti-Müllerian hormone (AMH) with risk of epithelial ovarian cancer (EOC) overall, and by tumor invasiveness and histology. A longitudinal study was used to assess patterns of hormonal changes during a single pregnancy, and in two consecutive pregnancies. Materials & Methods: A case-control study was nested within the Finnish Maternity Cohort and the Northern Sweden Maternity Cohort. A total of 1 052 EOC cases were identified through linkages with the cancer registries in both countries. For each case, 2-3 controls were selected. Cases and controls were matched on cohort, age and date at blood draw, as well as for parity at blood draw and at diagnosis (n=2 695). Odds ratios (OR) and corresponding 95% confidence intervals [CI] were estimated using conditional logistic regression. The longitudinal study was based on 71 pregnant Finnish women, who donated blood samples in each trimester of pregnancy. Results: Higher androgen concentrations were associated with an increased risk of overall EOC (e.g., testosterone ORT3 vs. T1: 1.56 [1.30-1.87], ptrend<0.0001), while the risk of endometrioid tumors increased with higher estradiol concentrations (ORT3 vs. T1: 2.76 [1.04-7.33], ptrend=0.03). Higher IGF-I was associated with a non-significant decrease in risk for invasive (ORT3 vs. T1: 0.79 [0.62-1.02], ptrend=0.07) and endometrioid tumors (ORT3 vs. T1: 0.55 [0.28-1.07], ptrend=0.07). The inverse association between IGF-I levels and risk of invasive EOC was stronger in analyses limited to women aged <55 years at diagnosis (ORT3 vs. T1: 0.74 [0.57-0.96], ptrend=0.03). No associations were observed between pre-diagnostic progesterone, SHBG, placental GH, and AMH with EOC risk overall, or by tumor invasiveness and histology. The longitudinal study showed that hormone concentrations were more strongly correlated between consecutive trimesters of a pregnancy than between the 1st and 3rd trimesters. Further, 3rd trimester hormone concentrations can be estimated from 1st or 2nd trimester measurements. Conclusion: Higher pre-diagnostic androgens, estradiol, and IGF-I are associated with EOC risk, and associations differ by tumor invasiveness and histology.