Abstract 2765: Combination strategies for management of ovarian cancer using doxorubicin and withaferin A

Abstract

Abstract Ovarian cancer is the 5th cause of cancer death in women with a mortality rate of 70%. Main treatment options include cytoreductive surgery with platinum-based therapy. However, 70% of patients relapse due to the carcinomas becoming platinum-resistant. As an alternative method, doxorubicin (Dox) is used for the treatment of several cancers, including ovarian. However, due to severe side effects, Dox is used as a second-line treatment strategy despite better patient response rates. To overcome this problem, we developed a novel treatment strategy that combines Dox with Withaferin A (WFA). WFA has been used as an anti-inflammatory and anti-bacterial compound in traditional Indian medicine. More recently, it has gained attention as an anti-cancer compound to prevent tumor growth, angiogenesis, and metastasis. We propose that combination of Dox with WFA will enhance the therapeutic effect of Dox so a lower dose of Dox can be used and many side-effects avoided. We used epithelial ovarian cancer cell line A2780 as our in vitro model. Based on our results, combination of Dox with WFA increased cell death over Dox or WFA alone measured by MTT assays. In particular, combination of Dox 200nM with WFA 2μM resulted in 90-95% cell death after 48 hr of treatment. Early apoptosis marker Annexin V-FITC was used to confirm these results as well as TUNEL assay for DNA damage. In addition, we have studied the signaling mechanism responsible for cell death through the inactivation of pro-survival Akt pathway. We demonstrated that down regulation of mTOR/p70S6K leads to autophagy and confirmed this with transmission electron microscopy, autophagy marker LC3B, and cleaved caspase 3. We have also validated this combination therapy in vivo using a xenograft model of ovarian cancer and showed reduction in tumor growth and weight as well as reduced Ki67 and CD31 staining. Mice tolerated receiving low dose of Dox (1 mg/kg) and combination Dox (1mg/kg) + WFA (2 mg/kg), whereas mice receiving high dose of Dox (9 mg/kg) did not tolerate treatment and died within 6 six days of treatment. Three dimensional tumor growth studies showed that treatment of tumors with Dox and WFA suppressed tumors growth by 80% within 3 days of treatment compared to untreated tumors. This work was supported by a grant from NCI CA124630 (SSK).Three dimensional tumor growth studies were performed in association with Vivo Biosciences Inc., Birmingham, AL. 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 2765. doi:1538-7445.AM2012-2765