Differential effects of choline on TLR2/4 mediated signaling through possible regulation of toll-interacting protein in hepatocellular carcinoma cell lines

Abstract

Toll-like receptor (TLR) mediated inflammatory status plays an important role in development and progression of hepatocellular carcinoma (HCC). Toll-interacting protein (TOLLIP) has an inhibitory effect on TLR-mediated inflammatory signalling and expression profile of TOLLIP varies between malignancies including HCC. Cholinergic anti-inflammatory pathway (CAP) is an endogenous mechanism that controls inflammatory status via α7nicotinic acetylcholine receptors (α7nAChR). This study aims to investigate the effect of CAP-acting agent choline on TOLLIP and its related TLR-mediated inflammatory response in HCC cells with distinct differentiation stages. The expression patterns of α7nAChR, TLR2/4, TOLLIP, IL6,NFkB genes were evaluated by RT-PCR and ELISA in the presence of choline, along with the real-time cell proliferation and migration in HEP3B and SNU449 HCC cell lines. The interaction between choline and TOLLIP assessed by using in-silico analyses. Choline downregulated TOLLIP in Hep3B and SNU449 cells. However, the expressions of α7nAChR, NF-κB, IL-6, TLR2 and TLR4 showed a decreased pattern in well differentiated HEP3B cells, while an increased pattern in poorly differentiated SNU449 cells. Choline might exert differential effects in TLR2/4-dependent signalling based on the differentiation stages of the HCC cells, suggesting its potential therapeutic effects in earlier stages of HCC which might be result of its partial modulation of TOLLIP.