BolA family member 2 enhances cell proliferation and predicts a poor prognosis in hepatocellular carcinoma with tumor hemorrhage

Objective: BolA family member 2 (BOLA2) is a novel gene highly associated with human hepatocellular carcinoma (HCC) progression. Tumor hemorrhage (TH) acts as a poor marker for HCC patients and is a community affair in the tumor microenvironment. In the present study, we examined a possible association between BOLA2 levels and HCC patients with TH. Methods: The mRNA and protein levels of BOLA2 were determined in two independent cohorts of HCC specimens by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) analysis, respectively. Survival curves and Cox regression models were used to evaluate the prognosis of HCC patients. The CRISPR/Cas9 system was used to knock out BOLA2 in HCC cells, and the functional role of BOLA2 in HCC cell proliferation in vitro and growth in vivo was examined. Results: BOLA2 mRNA expression is significantly higher in HCC tumour tissue than in nontumour tissue. Immunohistochemistry analysis of HCC tissues showed that BOLA2 protein was significantly correlated with TH, a more metastatic phenotype and worse HCC survival. The potential clinical relevance of BOLA2 expression and TH was validated by a Cox regression model. Furthermore, loss-of-function studies determined that BOLA2 plays critical roles in promoting iron overload, tumor growth and TH. Bioinformatics analysis from Gene Expression Profiling Interactive Analysis (GEPIA) revealed that BOLA2 is closely associated with the activation of p62-Keap1 signalling and ATG4B expression. These results were confirmed by immunohistochemistry analysis in HCC tissues. Conclusions: Our results suggest that BOLA2 plays an important role in cancer biology and is an independent predictor of prognosis in HCC.