Growth suppression of human pancreatic cells by a novel PKCβ inhibitor, enzastaurin

Abstract

14141 Background: Human pancreatic cancer is a devastating disease. Standard therapy, gemcitabine, is not able to alter the natural history of the disease. Targeting intracellular signaling molecules has proven to be a powerful approach in cancer therapy. Protein kinase C (PKC) family has been implicated in many human cancers including pancreatic cancer. Methods: In this pre-clinical study, we evaluated the effect of a novel small molecule inhibitor, enzastaurin, for PKCβ on human pancreatic cancer cells. We utilized MTT assay to assess cell proliferation and viability. To evaluate cell transforming activity, soft agar colony forming assay was used. Results: We showed that with addition of 20μM enzastaurin into the culture, the proliferative growth of two pancreatic cancer cell lines, Panc1 and L3.6p1, was significantly attenuated, as measured by the MTT assay. In addition, the combination of enzastaurin and a low dose of gemcitabine (25 nM) resulted in a synergistic cytotoxic effect in L3.6p1 cells. Further, the in vitro tumorogenicity assay demonstrated that the L3.6p1 cells treated with enzastaurin (20μM) formed much smaller colonies than the control parental cells in 0.4% soft-agar. Consistent with the in vitro cell proliferation results, the combination of enzastaurin and the low concentration of gemcitabine (25nM) further reduced the numbers and sizes of colonies in the soft-agar. Conclusions: Collectively, our data indicate that enzastaurin can effectively suppress the proliferation and in vitro transforming activity of the pancreatic cells, and more effectively when applied in combination with the low dose of gemcitabine. No significant financial relationships to disclose.