title: Glucocorticoid regulation of SLIT/ROBO tumour suppressor genes in the ovarian surface epithelium and ovarian cancer cells.
abstract: The three SLIT ligands and their four ROBO receptors have fundamental roles in mammalian development by promoting apoptosis and repulsing aberrant cell migration. SLITs and ROBOs have emerged as candidate tumour suppressor genes whose expression is inhibited in a variety of epithelial tumours. We demonstrated that their expression could be negatively regulated by cortisol in normal ovarian luteal cells. We hypothesised that after ovulation the locally produced cortisol would inhibit SLIT/ROBO expression in the ovarian surface epithelium (OSE) to facilitate its repair and that this regulatory pathway was still present, and could be manipulated, in ovarian epithelial cancer cells. Here we examined the expression and regulation of the SLIT/ROBO pathway in OSE, ovarian cancer epithelial cells and ovarian tumour cell lines. Basal SLIT2, SLIT3, ROBO1, ROBO2 and ROBO4 expression was lower in primary cultures of ovarian cancer epithelial cells when compared to normal OSE (P<0.05) and in poorly differentiated SKOV-3 cells compared to the more differentiated PEO-14 cells (P<0.05). Cortisol reduced the expression of certain SLITs and ROBOs in normal OSE and PEO-14 cells (P<0.05). Furthermore blocking SLIT/ROBO activity reduced apoptosis in both PEO-14 and SKOV-3 tumour cells (P<0.05). Interestingly SLIT/ROBO expression could be increased by reducing the expression of the glucocorticoid receptor using siRNA (P<0.05). Overall our findings indicate that in the post-ovulatory phase one role of cortisol may be to temporarily inhibit SLIT/ROBO expression to facilitate regeneration of the OSE. Therefore this pathway may be a target to develop strategies to manipulate the SLIT/ROBO system in ovarian cancer.
authors: Medical Research Council Centre for Reproductive Health, The University of Edinburgh, Edinburgh, United Kingdom.
authors: Rachel E
authors: RE
authors: Dickinson
authors: K Scott
authors: KS
authors: Fegan
authors: Xia
authors: X
authors: Ren
authors: Stephen G
authors: SG
authors: Hillier
authors: W Colin
authors: WC
authors: Duncan
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D000077216:Carcinoma, Ovarian Epithelial; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D052138:Genes, Neoplasm / Q000235:genetics*; D005938:Glucocorticoids / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology; D009375:Neoplasms, Glandular and Epithelial / Q000235:genetics* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D000097905:Roundabout Proteins
chemical_list: D005938:Glucocorticoids; D006854:Hydrocortisone; D009419:Nerve Tissue Proteins; D011965:Receptors, Glucocorticoid; D011971:Receptors, Immunologic; D025521:Tumor Suppressor Proteins; D000097905:Roundabout Proteins