Expression of cancer-testis antigen SPANXB and its mechanism in affecting hepatocellular carcinoma progress

Abstract

Objective·To analyze the expression of cancer-testis antigen (CTA) family member SPANXB (sperm protein associated with the nucleus on the X chromosome B) in liver cancer and its correlation with the prognosis of liver cancer patients, and to explore the impact of SPANXB on liver cancer cell proliferation and its potential mechanism.Methods·By using liver cancer sample data from the cancer genome atlas (TCGA) database, the expression of SPANXB in liver cancer tissue and its correlation with patient survival were analyzed. By constructing stable knockdown of SPANXB and stable overexpression of SPANXB in liver cancer cell lines, the effects of SPANXB on liver cancer cell proliferation were evaluated with live cell imaging experiments, EdU cell proliferation experiments and plate clone formation experiments. The regulatory pathways of SPANXB in liver cancer cell proliferation were explored through RNA-sequence (RNA-seq), and the effect of SPANXB on liver cancer cell cycle was validated through cell cycle experiments. Immunoprecipitation-mass spectrometry (IP-MS) was used to explore the proteins that interacted with SPANXB, and co-immunoprecipitation (Co-IP) was used to verify their interaction.Results·The expression of SPANXB mRNA in liver cancer tissues was higher than that in normal tissues (P=0.003), and was negatively correlated with the survival of liver cancer patients. Stable knockdown of SPANXB could reduce the proliferation and clone formation ability of liver cancer cells, while stable overexpression of SPANXB could promote these processes. The analysis results of RNA-seq showed that knockdown of SPANXB could lead to downregulation of DNA replication and G1/S cell cycle transition-related pathways. The results of cell cycle experiments showed that knockdown of SPANXB could result in changes in the liver cancer cell cycle. The results of IP-MS and Co-IP showed that SPAXNB interacted with cell cycle-related proteins such as mitotic arrest defect 2-like protein 1 (MAD2L1) and WD repeat domain 5 (WDR5).Conclusion·The high expression of SPANXB is negatively correlated with the prognosis of liver cancer. SPANXB may regulate the cell cycle and enhance the proliferation activity of liver cancer cells by interacting with MAD2L1 and WDR5.

Keywords

• cancer-testis antigen (cta)
• sperm protein associated with the nucleus on the x chromosome b (spanxb)
• liver cancer
• cell cycle