Glucocorticoids inhibit cell death in ovarian cancer and up-regulate caspase inhibitor cIAP2

Abstract

Purpose: Almost all patients with epithelial ovarian cancer receive chemotherapy and, concurrently, the synthetic steroid hormone dexamethasone to alleviate the side effects. This study aims to test the impact of steroid hormones on the apoptosis of epithelial ovarian cancer cells and to identify its mediators.

Experimental design: Tumor cell lines from 19 patients with advanced epithelial ovarian cancer were analyzed for glucocorticoid receptor, estrogen receptor, progesterone receptor, and androgen receptor expression. Cells were incubated with corresponding steroid hormones at serum-equivalent doses in hormone-depleted medium. Apoptosis was induced by application of tumor necrosis factor-related apoptosis-inducing ligand or staurosporine and determined by poly(ADP-ribose)polymerase cleavage and cell survival. Microarray with 8K cDNA chips including apoptosis-relevant genes was used to study genes regulated by glucocorticoids.

Results: In cell culture, tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in OV-MZ-30 and OV-MZ-31 cells was reduced after treatment with dexamethasone or cortisol, but not with estradiol, progesterone, or androstenedione. Microarray analysis revealed a 7-fold up-regulation of the caspase inhibitor cIAP2 by dexamethasone in OV-MZ-30 and OV-MZ-31 cells. cIAP2 up-regulation by glucocorticoids was confirmed by RT-PCR and Western blot analysis in OV-MZ-30, OV-MZ-31, OV-CAR3, and SK-OV-3 cells. Down-regulation of cIAP2 expression by small interfering RNA sensitized SK-OV-3 cells to apoptosis inducer staurosporine. Under clinical conditions, treatment with dexamethasone was associated with significant up-regulation of cIAP2 in the ascites cells.

Conclusions: Activation of the glucocorticoid receptor in epithelial ovarian cancer cells caused an anti-apoptotic effect associated with the enhanced cellular expression level of cIAP2. Dexamethasone pretreatment of epithelial ovarian cancer patients receiving apoptosis-inducing chemotherapy raises questions about a negative effect on antitumor efficacy.