Abstract: Objective The experiment aimed to study the protective effects and its mechanism of caffeic acid phenethyl ester (CAPE) on the lipotoxicity of hepatocytes in vitro. Methods Wild type L02 cells and peroxisome proliferator-activated receptor coactivator 1α (PGC1α) knockdown LO2 cells were respectively divided into control, palmitate- and palmitate plus CAPE-intervened groups. In palmitate-intervened group, the cells were cultured at 300 mM palmitate for 7 days, and in palmitate plus CAPE-intervened cells were cultured at 10μM CAPE and 300mM palmitate for 7 days. Cell triglycerides (TG), and tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels in the supernatants were detected. The mitochondrial reactive oxygen species (ROS) was measured by flow cytometry, the PGC1α and superoxide dismutase 2 (SOD2) mRNA were detected by qPCR, and the PGC1α proteins were detected by Western blotting. Results The cell TG level in palmitate-intervened group was (16.92±1.43)mg/g protein, significantly higher than [(10.53±0.81)mg/g protein, P<0.05] in palmitate plus CAPE-intervened group; the TNF-α and IL-6 levels in supernatants were (117.6±3.72)pg/ml and (67.9±2.7)pg/ml, both significantly higher than [(74.88±3.37)pg/ml and (53.94±2.39)pg/ml, respectively, P<0.05] in palmitate plus CAPE-intervened group; the ROS level was (1.7±0.06), much higher than [(1.36±0.04), P<0.05] in palmitate plus CAPE-intervened group; the SOD2 and PGC1α mRNA levels in palmitate plus CAPE-intervened group were (0.76±0.03) and (0.73±0.04), significantly higher than [(0.55±0.05) and (0.57±0.03), P<0.05] in palmitate-intervened group; the PGC1α protein expression was more strong than in palmitate-intervened group. After PGC1α knockdown, the cell TG level in palmitate plus CAPE-intervened knockdown L02 cells was (23.73±1.95)mg/g protein, not significantly different compared to (25.86±1.02)mg/g protein in palmitate-intervened cells (P>0.05), supernatant TNF-α and IL-6 levels were (128.33±4.41)pg/ml and (80.33±3.76)pg/ml, not significantly different compared to (145.78±5.79)pg/ml and (87.23±4.85)pg/ml in palmitate-intervened cells (P>0.05); the mitochondrial ROS level was (1.83±0.25), also not significantly different compared to (2.05±0.14) in palmitate-intervened group (P>0.05). Conclusion The CAPE could effectively protect the L02 cells from lipotoxicity, which might be through PGC1α pathway activation.

Key words: L02 cells, Caffeic acid phenethyl ester, Peroxisome proliferator-activated receptor coactivator 1α, Mitochondrial reactive oxygen species, In vitro