Abstract 5236: Bitter melon juice causes strong efficacy towards pancreatic cancer stem cells by modulating the hedgehog signaling pathway

Abstract

Abstract According to ACS estimates for year 2015, ∼48,960 new cases of pancreatic cancer (PanC) would be diagnosed with 40,560 associated deaths in the US alone. The median life of PanC patients post diagnosis is <6 months and overall 5 year survival is 3-5%. Thus, there is an urgent need for newer strategies to improve the disease outcome in these patients. Recently, considerable efforts have been directed towards natural dietary/non-dietary agents for both prevention/intervention of PanC. One such dietary agent, bitter melon (Momordica charantia) from Cucurbitaceae family, is now being extensively evaluated for its efficacy against various malignancies including PanC. Recently, we have shown significant growth inhibitory effects of bitter melon juice (BMJ) against a panel of PanC cells including Mia PaCa-2 xenograft tumors. Our studies also showed BMJ activity against both gemcitabine (frontline chemotherapeutic in PanC patients) sensitive as well as resistant PanC cell lines. Since the presence of cancer stem cells (CSC) is now recognized as the main cause for initiation, promotion and drug-resistance as well as relapse of most of the cancers, including PanC, there is a possibility that BMJ was affecting the CSC population in the PanC cells. Accordingly, the present study was aimed to determine whether BMJ has the potential to target CSC in PanC. We isolated CSC enriched (CD44+CD24+EpCAMhigh) cell population from the PanC cell lines, MiaPaCa2, PANC1 and AsPC1 and subjected them as well as the unsorted cells to sphere cluster formation assays in the presence or absence (single vs. multiple time treatment) of BMJ (0.25-2% v/v). The% of floating spheroids generated in the sphere cluster assays after 1-2 weeks were determined. The results indicated a dose-dependent effect of BMJ on both number and size (volume) of spheres, with 2% BMJ showing a significant reduction in both number and size of generated spheres in all PanC cell lines; single treatment of BMJ was found to be equally effective as multiple dosing regimens. Since formation of spheroids under specific in vitro conditions is a measure of stemness, our results show that BMJ has the potential to target the self-renewal of CSCs in PanC cell lines. Subsequent studies employing real time RT-PCR and immunofluorescence showed BMJ effect to be mediated in part by a significant down regulation in the expression of CSC marker CD44, CD133, and hedgehog (Hh)-pathway members in PanC cell lines. Further studies found that BMJ also decreases the protein levels of Hh-pathway members SHH and SMO in MiaPaCa2 xenograft tumors. Together, these are significant findings as they clearly show that BMJ interferes with the kinetics of CSC pool expansion via targeting various regulatory signals associated with the survival and multiplication of CSC pool leading to effective anti-cancer efficacy against PanC cells and their resistant phenotypes. Citation Format: Rajesh Agarwal, Deepanshi Dhar, Chapla Agarwal, Gagan Deep. Bitter melon juice causes strong efficacy towards pancreatic cancer stem cells by modulating the hedgehog signaling pathway. [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 5236.