Abstract 1039: HO-3867, is selectively cytotoxic to ovarian cancer cells through a dual mechanism of action involving the STAT3 and AKT pathways .
Authors: McCann Georgia A. , Rath Kellie S. , Naidu Shan , Lata Pushpa , Hemant Bid , Sudhakar Meryl , Hideg Kálmán , Houghton Peter , Kuppusamy Periannan , Cohn David E. , Selvendiran Karuppaiyah 
Published: August 2014

Objective: The development of anticancer drugs that selectively kills cancer cells while sparing the surrounding healthy tissues is of paramount importance for safe and effective anti-cancer therapy. We have developed a novel class of compounds that are fluoro-substituted analogs of curcumin, called diarylidenylpiperiden-4-ones (DAPs). We hypothesize that the structural backbone of DAP compounds would have cytotoxic activity, and the -NOH moiety would function as a tissue-specific modulator of this cytotoxicity via its anti-oxidant properties. The goal of this study was to analyze the differential cytotoxic effects of one of these compounds, HO-3867, on both ovarian cancer and normal cells.

Methods: Protein expression in pro-apoptotic and survival signaling pathways were analyzed via western blotting, and immunofluorescence assays using human ovarian cancer (SKOV-3) and normal ovarian surface epithelial (hOSE) cell lines treated with 10 μM HO-3867. Flow cytometry was used to quantify apoptosis and immunohistochemistry was performed to analyze cellular localization of proteins. The selective cytotoxic effect of HO-3867 was verified using STAT3 cDNA and Akt siRNA transfection. In vivo analysis was performed on mice administered oral HO-3867 using histopathological analysis and TUNEL assays. Efficacy of HO-3867 proved in STAT3 knockdown SKOV3 ovarian cancer cell line.

Results: HO-3867 did not affect the proliferation rate of hOSE cells while showing potent cytotoxic activity against SKOV-3 cells. In vivo histopathological evaluation of internal organs collected from treated adult mice revealed no evidence of toxicity. TUNEL staining of collected tissues suggested that selective apoptotic induction was limited to neoplastic cells in tumor xenografts. HO-3867 protected the normal cells by up-regulating the pro-survival protein pAkt. Tumor cells were targeted through downregulation of pAkt, pStat3, pErk1/2 and Bcl2 and upregulation of p21 and p53. Furthermore, HO-3867 was selectively regulates kinase activity in ovarian cancer cells and compared with hOSE cells. In addition, HO-3867 treated into STAT3 knockdown SKOV3 cells, resulted in the decreased apoptosis. These data indicated that HO-3867 induced apoptosis through the targeting STAT3.

Conclusion: Our results showed that HO-3867 protects normal cells while retaining antiproliferative activity against ovarian cancer cells. Increased levels of pAkt and the free radical-scavenging effects of the pro-nitroxide N-hydroxypyrroline group mediate this selective protection. The results suggest that the antioxidant-conjugated DAPs may be useful as safe and effective anticancer agents for treatment of ovarian cancer

Citation Format: Georgia A. McCann, Kellie S. Rath, Shan Naidu, Pushpa Lata, Bid Hemant, Meryl Sudhakar, Kálmán Hideg, Peter Houghton, Periannan Kuppusamy, David E. Cohn, Karuppaiyah Selvendiran. HO-3867, is selectively cytotoxic to ovarian cancer cells through a dual mechanism of action involving the STAT3 and AKT pathways . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1039. doi:10.1158/1538-7445.AM2013-1039