Abstract 3516: Tetrandrine promotes pancreatic cancer cell apoptosis in vitro and tumor regression in vivo

Abstract Introduction: Resistance to apoptosis is a hallmark of tumor progression and therapeutic failure in cancer, including Pancreatic Cancer. Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer related deaths in the United States with an overall five-year survival rate of less than five percent. The current standard treatment/s for PDAC are largely ineffective. There is an urgent yet unmet need for development of therapeutic agents for the treatment of PDAC. In the present study, we investigated the effects of Tetrandrine (a bis-benzylisoquinoline alkaloid) derivative- TET, on growth and viability of pancreatic cancer in vitro and in Xenograft models in vivo. Methods: Pancreatic Cancer cell lines: PANC-1 (epitheloid carcinoma), BxPC3 (Pancreatic Ductal Adeno-Carcinoma) and MiaPaCa2 (pancreatic carcinoma) were used in this study. Cytotoxicity was evaluated using the Crystal violet and MTT survival assays. Apoptosis was monitored by Flow cytometry following Annexin V/PI staining. Nuclear morphology was visualized by Immunofluorescence. Western Blot analysis was used to measure protein expression. Human pancreatic cancer (BXPC3) derived xenografts were generated in NOD/ SCID mice and TET (40 mg/kg body weight) was orally administered daily for four weeks. Tumor growth (measured as tumor volume by Vernier Caliper) and body weights were measured on alternate days. Tumor weight was measured at the end of the experimental period, prior to xenograft tissue harvesting. Results: TET inhibited growth and promoted cell death of pancreatic cancer cells in both dose and time dependent manner with an IC50 in the range of 5-10μM at 72 hr. The effects of TET were irreversible and there was progressive cell death with increasing time and at higher concentrations of TET. Treatment with TET resulted in nuclear condensation and apoptotic body formation, activation of caspase 3 and PARP cleavage, indicating apoptotic cell death. Moreover apoptosis was confirmed by flow cytometry after Annexin V and PI staining. TET administration not only halted the growth of BXPC3 derived xenografts, but also decreased tumor volume (TET treated vs PBS treated) over treatment period. Apoptosis (measured by TUNEL assay) was also observed in tumor tissues following TET treatment in vivo. Conclusion: These results show for the first time, that TET inhibits pancreatic cancer cell growth in vitro and induces pancreatic tumor regression in vivo in part by apoptosis. These results highlight the potential use of TET in treatment of pancreatic cancer. Acknowledgement: Financial support from following Sources is gratefully acknowledged: Carroll W. Feist endowed Chair Funds (Koul H), FWCC support and Chair commitment funds (Koul H) from the Chancellor and from the Dean School of Medicine- LSUHSC-Shreveport. All the members of Koul laboratory for their suggestions and help. Citation Format: Karnika Singh, Prakash Srinivasan Timiri Shanmugam, Sweaty Koul, Qin Dong, Neil Koul, Hari K. Koul. Tetrandrine promotes pancreatic cancer cell apoptosis in vitro and tumor regression in vivo. [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 3516.