Toll-like receptor 4 mediates cross-talk between peroxisome proliferator-activated receptor γ and nuclear factor-κb in mouse melanoma (b16f10) in vitro

Nasim Dana,1,* Shaghayegh haghjooy javanmard ,2 Golnaz vaseghi,3

1. Applied Physiology Research Center, Cardiovascular research institute, Isfahan University of Medical Sciences
2. Applied Physiology Research Center, Cardiovascular research institute, Isfahan University of Medical Sciences
3. Isfahan Cardiovascular research center, Department of Pharmacology, Cardiovascular research institute, Isfahan Universit

Abstract

Introduction

There is increasing evidence that chronic activation of nuclear factor-κb (nf-κb), which is an essential signaling pathway involved in conveying inflammatory signals, is causally related to cancer pathology. activation of toll-like receptor-4 (tlr-4) signalling by lipopolysaccharide (lps), induces nuclear factor-κb (nf-κb). interestingly, it is known that activation of peroxisome proliferator-activated receptors (ppar-γ) can exert anti-inflammatory effects and suppresses nf-κb transcriptional activity. herein, we investigated the modulatory effects of pioglitazone as ppar-γ agonist on lps-mediated inflammatory responses and tlr4 signaling in melanoma cancer cell line(b16f10).

Methods

B16f10 cells were treated with lps (5 µg/ml) with or without pioglitazone (1,10,100,300 µm) and mtt assay was done .the expression of tlr4, myeloid differentiation primary-response gene 88 (myd88) and nuclear factor kappa-light-chain-enhancer of activated b cells (nf-κb) mrna were detected by quantitative real time-polymerase chain reaction method(qrt-pcr).

Results

Results showed that pioglitazone treatment without lps significantly decreased cell viability only at 300 µm (p<0.001).pioglitazone treatment with lps significantly decreased cell viability at all pioglitazone concentrations (p<0.001). by qrt-pcr analysis, results showed that pioglitazone concentration-dependently downregulated mrna expressions of tlr4, myd88, nf-κb.

Conclusion

These results demonstrate that pioglitazone negatively regulates tlr4 signaling in lps-stimulated melanoma cells. it is may be exerts its anti-inflammatory effect by this way. it provides new insight to understand the mode of action of ppar-γ agonist for its anti-cancer effects.

Keywords

Melanoma, lps, pioglitazone, tlr4 signaling, peroxisome proliferator-activated receptor-γ