Background: Cervical cancer is one of the leading cause of mortality among women in US. Naturally occurring dietary compounds have gained increasing attention for their anticancer effects. Cucurbitacins, tetracyclic triterpenoid compound, belong to a family of Cucurbitaceae have shown promising anti-cancer activity. Herein, we investigated the potential anti-cancer effects of a novel analogue of cucurbitacin D (Cuc D) against cervical cancer in in vitro and in a xenograft mouse model.

Methods: In our study, we used human cervical cancer cells (CaSki and SiHa). Cells were treated with Cuc D (0.05 to 1μM) for 48 and 72 hrs. MTS and colony formation assays were performed to investigate the effects of Cuc D on cell viability and proliferation. Western Blot analysis was performed to investigate the effects of Cuc D on cell proliferation and apoptotic markers. To determine the therapeutic effects of Cuc D, we used female athymic nude mice and injected CaSki cells (4 × 106) into the cervix to develop orthotopic xenograft tumors. Cuc D (1 mg/kg body weight) was administered through intratumoral injection four weeks post-tumor cell injection. Tumor volume in these mice were recorded bi-weekly.

Results: Cuc D inhibited cell viability of cervical cancer cells in a dose-dependent manner. IC50 of Cuc D was observed 400 nM and 250 nM in Caski and SiHa cells, respectively. Cuc D treatment effectively inhibited growth of cervical cancer cells which was determined by decreased cell proliferation and colony formation assays. Cuc D treatment induced apoptosis in cervical cancer cells as measured by enhanced Annexin V staining. Western blot result also illustrated cleavage in PARP protein in Cuc D treated cells which further confirms apoptosis induction. Cuc D treatment also inhibited PI3K and c-Myc protein levels and phosphorylation of STAT3 and Rb proteins. In addition, Cuc D treatment induced the cell cycle inhibitory proteins (p21 and p27) and PTEN and the expression of a tumor suppressor microRNA, miR-145, as determined by qRT-PCR. In an orthotopic tumor xenograft mouse model, Cuc D treatment effectively inhibited tumor growth as compared to vehicle control treated mice.

Conclusion: Taken together, our results demonstrate potent anti-cancer efficacy of Cuc D in cervical cancer cells via modulation of key onco/tumor suppressor proteins. Thus, Cuc D could be a useful therapeutic agent for cervical cancer treatment.

Citation Format: Mohammed Sikander, Bilal Bin Hafeez, Fathi T. Halaweish, Murali M. Yallapu, Meena Jaggi, Subhash C. Chauhan. Novel cucurbitacin analogue Cuc D exhibits potent anti-cancer activity in cervical cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3081.