Peptide identification of hepatocyte growth-promoting factor and its function in cytoprotection and promotion of liver cell proliferation through the JAK2/STAT3/c-MYC pathway

Hepatocyte growth-promoting factor (pHGF) has a significant effect in promoting liver cell proliferation and restoring liver function. In this study, 815 short peptides of pHGF were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), of which 574 short peptides were assigned to 152 proteins related to hemoglobin subunits and some catalytic enzymes, indicating that pHGF might participate in the oxidationreduction process by regulating reactive oxygen species (ROS) production. Proteomic analysis was used to identify the differentially expressed proteins (DEPs) in SMMC-7721 and L-02 cells after pHGF treatment, which suggested that pHGF had a significant impact on the JAK-STAT signaling pathway and the cell cycle of liver cells. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis revealed the mechanisms through which pHGF might activate the JAK2/STAT3/c-MYC pathway to up-regulate the expression of CDK4/6, thereby accelerating the G1/S transition to promote liver cell proliferation. These findings, for the first time, indicate the potential role of pHGF against the early or middle stages of acute, sub-acute, and chronic severe hepatitis. pHGF was also found to restore the reduced SOD1 and SOD2 protein levels that result from H2O2 exposure and significantly increase the HO-1 protein levels in L-02 cells, thus improving the viability of L-02 cells that have been damaged by H2O2 by reducing the ROS and lipid peroxidation levels.