Sorafenib is one of the options for advanced hepatocellular carcinoma treatment and has been shown to extend median overall survival. However, sorafenib resistance often develops a few months after treatment. Hence, developing various strategies to overcome sorafenib resistance and understand the possible mechanisms is urgently needed. We first established sorafenib-resistant hepatocellular carcinoma (HCC) cells. Then, we found that sorafenib-resistant Huh7 cells (Huh7/SR) exhibit higher glucose uptakes and express elevated fatty acid synthesis and glucose metabolism-related proteins than their parental counterparts (Huh7). The current study investigated whether sorafenib resistance could be reversed by suppressing fatty acid synthesis, using a fatty acid synthase (FASN) inhibitor, orlistat, in HCC cells. FASN inhibition-caused changes in protein expressions and cell cycle distribution were analyzed by Western blot and flow cytometry, and changes in glucose uptakes were also evaluated by 18F-FDG uptake. Orlistat remarkably enhanced the cytotoxicity of sorafenib in both Huh7 and Huh7/SR cells, and flow cytometry showed that combination treatment significantly increased the sub-G1 population in both cell lines. Western blot revealed that the combination treatment effectively increased the ratio of Bax/Bcl-2 and decreased expressions of pERK; additionally, the combination treatment also strongly suppressed fatty acid synthesis-related proteins (e.g., FASN and SCD) in both cell lines. Lastly, the 18F-FDG uptake was repressed by the combination treatment in both cell lines. Our results indicated that orlistat-mediated FASN inhibition could overcome sorafenib resistance and enhance cell killing in HCC by changing cell metabolism.
Keywords: fatty acid synthase; hepatocellular carcinoma; metabolism; sorafenib resistance.