The effect of fenofibrate, a PPARalpha activator on toll-like receptor-4 signal transduction in melanoma both in vitro and in vivo

Abstract

BACKGROUND: The anti-cancer effect of peroxisome proliferator-activated receptor (PPAR) alpha ligands on growth and metastatic potential of melanoma cells has been shown previously. However, the mechanism underlying these effects remains to be elucidated. Here, we investigated the effects of fenofibrate (PPAR ligand) on Toll-like receptor-4 (TLR-4) signaling in mice melanoma. METHODS: Mice melanoma cells (B16F10) were treated with fenofibrate or LPS or LPS + fenofibrate or pre-treated with CLI-095 (a TLR4 inhibitor), followed by fenofibrate. In in vivo model, C57BL/6 mice were subcutaneously injected with B16F10 cells (with/without LPS pre-treatment), and fenofibrate was administrated after development of palpable tumors. Cell proliferation, the expression level of Tlr4, Myd88, Nf-kappab1 genes, TLR-4 protein expression, TNF-alpha levels, and tumor volume were measured. RESULT: Our results indicated that fenofibrate significantly inhibited the Tlr-4, Myd-88, and Nf-kb1 mRNA expression and TNF-alpha concentration in B16F10 LPS-stimulated cells. In addition, blocking TLR-4 signaling increased the anti-inflammatory potential of fenofibrate. Also fenofibrate can reduce LPS-induced tumor volume, Tlr-4, Myd-88, Nf-kb1 mRNA, and TLR-4 protein expression in tumor tissue and also TNF-alpha level in tumor tissue lysate. CONCLUSION: Our data indicate that fenofibrate may exert its anti-melanoma effects via interaction with TLR4-dependent signaling pathway (TLR-4/MyD-88/ NF-kB).