Dehydroepiandrosterone inhibits the proliferation and induces the death of HPV‐positive and HPV‐negative cervical cancer cells through an androgen‐ and estrogen‐receptor independent mechanism

Abstract

Dehydroepiandrosterone (DHEA) has a protective role against epithelial-derived carcinomas; however, the mechanisms remain unknown. We determined the effect of DHEA on cell proliferation, the cell cycle and cell death in three cell lines derived from human uterine cervical cancers infected or not with human papilloma virus (HPV). We also determined whether DHEA effects are mediated by estrogen and androgen receptors. Proliferation of C33A (HPV-negative), CASKI (HPV16-positive) and HeLa (HPV18-positive) cells was evaluated by violet crystal staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) reduction. Flow cytometry was used to evaluate the phases of the cell cycle, and cell death was detected using a commercially available carboxyfluorescein apoptosis detection kit that determines caspase activation. DNA fragmentation was determined using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Flutamide and ICI 182,780 were used to inhibit androgen and estrogen receptors, respectively, and letrozol was used to inhibit the conversion of DHEA to estradiol. Our results show that DHEA inhibited cell proliferation in a dose-dependent manner in the three cell lines; the DHEA IC(50) doses were 50, 60 and 70 mum for C33A, CASKI and HeLa cells, respectively. The antiproliferative effect was not abrogated by inhibitors of androgen and estrogen receptors or by an inhibitor of the conversion of testosterone to estradiol, and this effect was associated with an increase in necrotic cell death in HPV-negative cells and apoptosis in HPV-positive cells. These results suggest that DHEA strongly inhibits the proliferation of cervical cancer cells, but its effect is not mediated by androgen or estrogen receptor pathways. DHEA could therefore be used as an alternative in the treatment of cervical cancer.