Dysregulated notch signaling plays an important role in the progression of pancreatic cancer. Previous studies have demonstrated that curcumin, the active ingredient in the spice turmeric can modulate notch activity. In this study, we have developed a novel curcumin analog SR1264 and have determined its effects on notch signaling in pancreatic cancer cells.

Methods: Five pancreatic adenocarcinoma cell lines (AsPC-1, MiaPaCa-2, PanC-1, BxPC-3 and Pan02) were used in the study. Cell proliferation was measured by hexosaminidase and colony formation assays. Apoptosis was determined by measuring caspase 3/7 activity and western blot analysis for caspase 3. Cell cycle analysis was performed by propidium iodide staining and flow cytometry. Real Time PCR and western blot analyses were used to measure mRNA and protein levels. For in vivo studies, nude mouse xenografts were developed with mouse pancreatic cancer cells (Pan02). The resulting effects of SR1264 treatment was assessed by measuring tumor volume. Immunohistochemistry was performed for CD31 (endothelial marker, surrogate for angiogenesis) and for COX-2, VEGF and Notch-1 expression.

Results: SR1264 treatment resulted in a dose and time dependent inhibition of proliferation and in colony formation in all 5 pancreatic cell lines. Conversely, SR1264 did not affect the proliferation of normal mouse embryo fibroblasts. The compound also induced apoptosis by activating caspase 3. Cell cycle analyses demonstrated that SR1264 induced G2/M cell cycle arrest, which was followed by the induction of apoptosis as evidenced by caspase-3 activation and an increased number of cells with a sub-G1 DNA fraction. Western blot analyses demonstrated that SR1264 downregulated the expression of cell cycle related proteins cyclin A, D1 and E, while upregulating p21Waf1. In addition, SR1264 significantly downregulated the expression of Notch-1, Jagged-1, Hey-1, Hes-1, COX-2, IL-8 and VEGF. To determine the effect of SR1264 on tumor growth in vivo, nude mice harboring pancreatic cancer tumor xenografts in their flanks were administered with the compound intraperitoneally every day for 21 days. SR1264 significantly inhibited tumor xenograft growth, with notably lower tumor volume and weight. Microvessel density, based on CD31 staining was also significantly lower in the tumors following SR1264 treatment when compared to tumors in controls. Real Time PCR and immunohistochemistry analyses demonstrated significant inhibition of COX-2, VEGF, and Notch-1, and cyclin D1 mRNA and protein expression in the tumors.

Conclusion: Together, these data suggest that SR1264 is an effective inhibitor of pancreatic tumor growth in vivo in part through downregulating Notch-1 protein and its downstream targets. Therefore, SR1264 may be a novel therapeutic agent for pancreatic cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5046.