Abstract 4653: 5F203-induced reactive oxidative species, DNA damage and apoptosis involves aryl hydrocarbon activation in ovarian cancer cells

Abstract

Abstract Ovarian cancer is the 2nd cause of death by gynecological malignancies after breast cancer. These tumors have poor prognoses because they are detected at advanced stages of disease and show acquired or intrinsic resistance to therapy.Benzothiazoles, agents with preclinical antitumor activity against ovarian and breast cancer models, belong to a novel mechanistic class which bind to the arylhydrocarbon receptor (AhR). Phortress the lysylamide prodrug of 2-(4-amino-3-methylphenyl)-5- fluorobenzothiazole (5F203) is currently under phase I clinical evaluation. We previously demonstrated that these compounds activate AhR signaling in sensitive breast cancer cells, the goal of this project was to evaluate the role of AhR in 5F203 activity in two human ovarian cell lines: IGROV-1 sensitive to 5F203 and SKOV-3 resistant to this agent. We observed by MTS assay IGROV-1 cell growth inhibition of 31.9±12.2% by 0.01 μM 5F203 and almost total growth inhibition (91.9±3.4%) after treatment of IGROV-1 cells with 1 μM 5F203. Pre-incubation with the AhR inhibitor ΔNF (1 μM), partially blocked the effect of 5F203 (inhibition of 21.6±4.7% and 27.7±5.3% respectively). In contrast, 5F203 failed to inhibit growth of SKOV-3 cells.5F203 (1 μM) induced AhR translocation from cytosolic to nuclear fractions evaluated by Western blot and confocal microscopy in IGROV-1 cells only. Moreover, activation of CYP1A1 related promoter sequences and EROD activity further indicated activation of AhR signaling. 5F203 treatment for 1h increased ROS and induced NFκB nuclear translocation only in IGROV-1 cells, effects which were attenuated by pre-treatment with ΔNF. Detection of γH2AX revealed DNA double strand breaks 2h post 5F203 treatment of IGROV-1 cells only. After 24h exposure, 5F203 resulted in increased IGROV-1 cell apoptosis, evaluated by DAPI staining of apoptotic bodies, increased pP53, caspase 3 and PARP cleavage. We also observed G1 cell cycle arrest, increased P21 expression and decreased cyclin D1 expression induced by 5F 203. We conclude that the antitumor/pro-apoptotic effects of 5F203 observed in IGROV-1 cells is mediated by AhR which may be a new molecular target in the treatment of ovarian tumors and that this agent may represent a potential novel treatment for ovarian cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4653. doi:1538-7445.AM2012-4653