Adenosine Induces Autophagy in Cholangiocarcinoma Cells

Abstract

Background/Aim: Cholangiocarcinoma is a lethal disease with increasing incidence worldwide. New therapeutic compounds are urgently needed for this disease. Here, the inhibitory effect of adenosine on cholangiocarcinoma cells was studied. Materials and Methods: Western blot analysis was used to study autophagy and flow cytometry to analyze cell death and the cell cycle. Results: Cholangiocarcinoma and immortalized cholangiocytes responded to adenosine differently, and adenosine inhibited cholangiocarcinoma cell growth by inducing autophagy. Adenosine failed to activate adenylyl cyclase in cholangiocarcinoma cell lines, but activated this enzyme in immortalized cholangiocytes. Adenosine treatment activated AMPK and led to phosphorylation of its downstream proteins including ULK and Raptor. In addition, autophagy induced by adenosine appeared to be a survival mechanism. The combination of adenosine with autophagy inhibitors greatly increased cell death, as compared to the use of either agent alone. Interestingly, immortalized cholangiocytes were more resistant to adenosine. Conclusion: Adenosine may have potential for application in cholangiocarcinoma treatment. Materials and MethodsCell culture. The intrahepatic cholangiocarcinoma cell line, HuCCA-1, was established by Prof. Stitaya Sirisinha at Chulabhorn Research Institute ( 22) and was also purchased from Japanese Collection of Research Bioresources (JCRB) Cell Bank (Osaka, Japan). HuCCA-1 was derived from a male Thai patient whose serum was positive for the O. viverrini antigen ( 22). The RMCCA-1 cell line, established from a peripheral cholangiocarcinoma specimen surgically obtained from a male Thai patient, was kindly 3769