Abstract C36: Is DHT involved in the action of TGF-β1 in epithelial ovarian cancer?

Abstract

Abstract Ovarian cancer is the ninth most common female cancer worldwide and the fifth leading cause of cancer-related death among women in developed countries. In Chile, ovarian cancer is the second cause of death from gynaecological cancer. This disease is characterized by a silent course, late detection, high angiogenesis, with a poor response to therapy and a low survival. It is postulated that epithelial ovarian cancer (EOC) arises from the ovarian surface epithelium (OSE), but also it has been suggested that epithelial cells from fimbrae of the fallopian tubes could be implicated as the possible site of this malignancy, such as high-grade serous carcinoma. There are several hypotheses that intend to explain the origin of ovarian cancer and one of them postulate that sex steroid hormones have been involved in the aetiology and/or progression of some EOCs. In fact, androgens receptor (AR) is expressed in OSE cells and also in the majority of ovarian cancers. The microenvironment of ovarian cancer cells is enriched in androgens, and high levels of this steroid have also been reported in ascitic fluid; this condition supports the hypothesis that androgens, which are present in the ovarian stromal compartment, can produce neoplastic conversion of OSE and epithelial cells into de inclusion cyst and/or also be involved in ovarian cancer progression. Therefore, it is important to evaluate if dihydrotestosterone (DHT) is involved in the regulation of TGF-β1 receptors and also TGF-β1 signaling pathway, which is a potent inhibitor mechanism of cell proliferation, in EOC. This work was done with two types of experiments: 1) ex-vivo, with tissues of inactive normal ovaries and EOC poorly differentiated obtained from 10 patients from Hospital Clinico Universidad de Chile, with informed consent approved by Ethical Committee of the Institution, in order to evaluate the detection of AR by immunohistotochemistry (IHC). 2) In vitro experiments with human ovarian surface epithelium cell line (HOSE) and human epithelial ovarian cancer cell line (A2780). Both human cell lines are a good model that represents the epithelial cells from inactive normal ovaries and from EOC, respectively. These cells were stimulated with DHT and also with TGF-β1 during 72 h. The AR expression in cell lines was analysed by RT- PCR and immunocytochemistry (ICC). On the other hand, in both cell lines, TGF-β1R1 and TGF-β1R2 were detected by ICC and also in basal condition and with 10 and 100nM of DHT, by western-blot. In addition, we used an AR siRNA in order to know if DHT is involved in the TGF-β1R1 and/or in TGF-β1R2 expression in A2780 cell line. Our results show that AR protein levels in EOC and A2780 are significantly higher than inactive normal ovaries and HOSE cells, respectively (p<0.05). In basal condition, TGF-β1R1 protein levels in HOSE cells were higher than in EOC cells, but no changes were found in TGF-β1R2 protein levels in A2780. When cellular lines were treated with 100nM DHT, TGF-β1R1 and TGF-β1R2 protein levels decreased (p<0.05) with respect to the control condition only in A2780 cells. Besides, a 45% of AR silencing was obtained with AR siRNA (100 pmol) at 72 h in A2780 cells. Then, these cells were stimulated with 100 nM of DHT and it was obtained a 30% protein increase of the TGF-β receptors. These preliminary results suggest that DHT could be involved in TGF-β1 signaling pathway in epithelial ovarian cancer. This work has been support by grant FONDECYT # 1110372 (to CR) Citation Format: Karla Kohan, Cristian Poblete, Margarita Vega, Carmen Romero. Is DHT involved in the action of TGF-β1 in epithelial ovarian cancer? [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr C36.