Girdin influences pancreatic cancer progression by regulating c-MYC expression.

Pancreatic ductal adenocarcinoma is a complex gastrointestinal tumor with high metastatic potential and poor prognosis. Actin-binding protein Girdin is highly expressed in a variety of tumors and promotes tumorigenesis and progression. However, the mechanisms underlying the involvement of Girdin in pancreatic cancer have not been clarified. In this study, we observed that the expression of Girdin was upregulated in pancreatic cancer cells. The siRNA-mediated gene knockdown experiments showed that reduced expression of Girdin in pancreatic cancer cells inhibited cell proliferation, migration, and invasion while promoting cell apoptosis. Functional assays revealed that c-MYC overexpression in pancreatic cancer cells could significantly increase the cell proliferation ability and rates of cell migration and invasion while decreasing the apoptosis rate. It has been shown that phosphorylation plays a role in the functional regulation of the c-MYC gene. Subsequently, we examined the expression level of c-MYC in cells with manipulated expression of Girdin and identified a positive correlation between Girdin expression and c-MYC expression. Moreover, we found that Girdin knockdown in c-MYC-overexpressing pancreatic cancer cells slowed cell growth, blocked the cell cycle progression, significantly promoted apoptosis, and markedly decreased the cell migration and invasion. This finding indicated that silencing Girdin could mitigate the effect of c-MYC on promoting proliferation and metastasis of pancreatic cancer. Overall, this study provided evidence that Girdin promoted pancreatic cancer development presumably by regulating the c-MYC overexpression.