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 oxidation-reduction 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.