The Dual Effects of Silibinin on Human Pancreatic Cells

Objective: Silibinin is a flavonoid with antihepatotoxic properties, and exhibits pleiotropic anticancer effects. However, the molecular mechanisms responsible for its anticancer actions in pancreatic cancer cells, and the effects on such cells and normal pancreatic cells, remain unclear. The objective of this study was to determine the effect of silibinin on human pancreatic cancer cells and normal ductal cells. Methods: Human pancreatic cancer cells (MIA PaCa-2 and PANC-1) and normal ductal cells (hTERT-HPNE) were cultured with 0-400 μM silibinin for 48 h. Thereafter, the proliferation, invasion, apoptosis, and signaling pathways of the pancreatic cells were evaluated. Results: Silibinin significantly inhibited the proliferation, invasion, and spheroid formation of human pancreatic cancer cells in vitro in a dosedependent manner (p<0.05). It also induced apoptosis in a dose-dependent manner. Western blot analysis showed that silibinin downregulated extracellular signaling-regulated kinase (ERK) and serine/threonine protein kinase (AKT) in human pancreatic cancer cells. It also upregulated microtubule associated protein 1 light chain 3 β (LC3B) and cleaved caspase-3 via c-Jun N-terminal kinases (JNK) signaling. On the other hand, silibinin increased the mRNA and protein levels of c-Jun, Twist-related protein 1, and Snail. It also decreased exogenous p53 levels, but increased endogenous c-Jun protein levels in human pancreatic cancer cells. However, silibinin did not affect cell viability and endogenous c-Jun levels in pancreatic normal ductal cells. It increased exogenous p53 levels, but decreased stemness-related gene expression in pancreatic normal ductal cells. Silibinin increased Ki-67 levels in pancreatic cancer cells, but decreased them in pancreatic normal ductal cells. Conclusion: Silibinin not only exerted anticancer effects by inhibiting AKTERK and JNK signaling, but also upregulated cancer stemness-related genes in human pancreatic cancer cells. These results suggest that silibinin should be used as a therapeutic agent for human pancreatic cancer with caution.