Fenofibrate antagonizes Chk2 activation by inducing Wip1 expression: implications for cell proliferation and tumorigenesis.

AIMS

Fenofibrate is a peroxisome proliferator-activated receptor alpha (PPARalpha) agonist that has been widely used to treat dyslipidemia. Previous studies have suggested that fenofibrate plays a role in cell proliferation and the development of hepatocarcinoma, but the underlying mechanism has not been fully characterized. In this report, we investigated whether fenofibrate treatment affected on the machinery of cell cycle checkpoint using nocodazole-induced cell cycle arrest.

MAIN METHODS

The human normal liver cell line, CCL13 cells were treated with nocodazole and fenofibrate. Flow cytometry was performed for cell cycle analysis, and checkpoint kinase 2 (Chk2) and phosphatase Wip1 were analyzed by Western blot.

KEY FINDINGS

Fenofibrate treatment overrode nocodazole-induced G2/M cell cycle arrest in a PPARalpha-independent manner. Mechanistically, fenofibrate treatment inhibited phosphorylation of checkpoint kinase Chk2 induced by nocodazole, and increased the expression of Wip1, a negative regulator of Chk2, suggesting that fenofibrate suppressed the nocodazole-induced G2/M cell cycle checkpoint through Wip1-mediated inhibition of Chk2 activation.

SIGNIFICANCE

These results reveal a novel role of fenofibrate in cell cycle checkpoint control and provide a possible mechanistic explanation for how fenofibrate promotes cell proliferation and carcinogenesis.