Expression of fatty acid synthase is regulated by PGC-1α and contributes to increased cell proliferation

We previously demonstrated that overexpression of peroxisome proliferator-activated receptor. coactivator-1 alpha (PGC-1 alpha) promotes increased cell proliferation and tumorigenic potential through upregulation of specificity protein 1 (Sp1) and acyl-CoA-binding protein (ACBP). Fatty acid synthase (FASN) is a key enzyme in fatty acid biosynthesis, and its expression in various cancers is associated with survival, poor prognosis and cancer recurrence. In the present study, we evaluated whether PGC-1 alpha regulated FASN expression in human colorectal cancer (SNU-C4 and HT-29) cells. We also examined whether cell proliferation was inhibited by shRNA-induced FASN knockdown in SNU-C4 and HT-29 cells. In all tested cell lines, FASN-shRNA knockdown inhibited cell proliferation, decreased antioxidant enzyme expression, and increased apoptosis and production of H2O2-induced reactive oxygen species (ROS). These findings indicated that FASN expression may enhance cell proliferation by regulating antioxidant enzyme production and resistance to ROS-induced apoptosis. We further provided evidence that FASN expression was regulated indirectly through upregulation of Sp1 and SREBP-1c by PGC-1 alpha. Overall, our results revealed that FASN expression, mediated by PGC-1 alpha, may play a positive role in cancer cell proliferation.