Fenofibrate reduces cisplatin-induced apoptosis by inhibiting the p53/Puma/Caspase-9 pathway and the MAPK/Caspase-8 pathway rather than by promoting autophagy in murine renal proximal tubular cells

Abstract

The main lesion of cisplatin nephrotoxicity is damage to proximal tubular cells due to increased apoptosis via the mitochondrial and death receptor pathways, which may be alleviated by appropriate promotion of autophagy. Fenofibrate, a peroxisome proliferator-activated receptor-alpha (PPAR-α) activator, is recently reported to promote autophagy as well as protect against cisplatin nephrotoxicity, although the mechanisms were only partially analyzed. Here, the detailed mechanisms of these putative protective effects were investigated in a murine renal proximal tubular (mProx) cell line. Fenofibrate attenuated cisplatin-induced apoptosis of mProx cells based on flow cytometry. As for the mitochondrial apoptotic pathway, the reagent reduced cisplatin-stimulated caspase-3 activation by decreasing the phosphorylation of p53, JNK, and 14-3-3, cytosolic and mitochondrial Puma accumulation, cytochrome C release to the cytosol, and resulting cytosolic caspase-9 activation. Fenofibrate also decreased cisplatin-stimulated activation of caspases-8 by suppressing MAPK and NFkB pathways and reducing the gene expression of TNF-α, TL1A, and Fas, main mediators of the death receptor apoptotic pathway. Autophagy defined by p62 reduction and an increase in LC3 II/I was promoted by fenofibrate in mProx cells under starvation. Autophagy inhibition using 3-MA further increased basal and cisplatin-induced caspase-3 and -8 activation, but had no influence on the inhibitory effects of fenofibrate on caspase activation. In conclusion, our study suggests fenofibrate to be a candidate agent to mitigate cisplatin nephrotoxicity by inhibiting the mitochondrial and death apoptotic pathways rather than by promoting autophagy.