CSIG promotes hepatocellular carcinoma proliferation by activating c-MYC expression

Area of Science:

• Oncology
• Molecular Biology
• Cell Biology

Background:

• Cellular senescence-inhibited gene (CSIG) protein is known to delay replicative senescence.
• The specific role of CSIG in tumorigenesis, particularly in hepatocellular carcinoma (HCC), remains largely undetermined.

Purpose of the Study:

• To investigate the expression and functional role of CSIG in HCC development and progression.
• To elucidate the molecular mechanisms underlying CSIG's involvement in HCC tumorigenesis.

Main Methods:

• Quantitative analysis of CSIG protein expression in human HCC tissues versus matched surrounding non-cancerous tissues.
• In vitro studies assessing the impact of CSIG modulation on HCC cell proliferation, colony formation, cell cycle, and apoptosis (using SMMC7721 and HepG2 cell lines).
• In vivo validation using a mouse xenograft model and investigation of CSIG's interaction with c-MYC protein.

Main Results:

• CSIG protein was significantly overexpressed in 86.4% of human HCC tissues compared to adjacent tissues.
• Overexpression of CSIG enhanced colony formation and proliferation of HCC cells in vitro and in vivo.
• Silencing CSIG induced cell cycle arrest and apoptosis in HCC cells.
• CSIG directly interacted with and stabilized c-MYC protein, increasing its levels, while CSIG knockdown enhanced c-MYC ubiquitination and degradation.

Conclusions:

• CSIG protein is upregulated in HCC and promotes tumor cell proliferation by stabilizing c-MYC.
• Targeting CSIG may represent a novel therapeutic strategy for hepatocellular carcinoma.