BMI1 overexpression is correlated with a poor prognosis and immune infiltration in hepatocellular carcinoma

Background:Owing to the occurrence of primary or secondary tolerance,the efficacy of immunotherapy for hepatocellular carcinoma(HCC)patients is limited.Therefore,the mechanism underlying this tolerance needs to be further investigated.B cell–specific Moloney murine leukemia virus integration site 1(BMI1)is associated with cancer stem cell tumorigenesis,progression,and the maintenance of the self-renewal.However,the effect of BMI1 expression on immune infiltration and prognosis in HCC is still unclear.Methods:To assess the relationship between BMI1 expression and HCC prognosis and immune infiltration,the GEPIA database,TIMER database,and K-M plotter were used.TIMER database was used to determine the levels ofBMI1 in various tumor tissues and corresponding normal tissues,and examine the association between BMI1 expression and tumor-infiltrating immune cells.GEPIA database was applied to determine BMI1 expression in various tumor tissues and corresponding normal tissues.K-M Plotter was used to study the relationships among BMI1 expression,clinicopathological features,and survival rates.Results:BMI1 expression was markedly higher in various solid tumors compared with that in the respective normal tissues,including HCC,and high expression led to poor relapse-free survival and overall survival in HCC patients.BMI1 overexpression was also correlated with the infiltration of immune cells(eg,B cells,CD8+T cells,CD4+T cells,dendritic cells,neutrophils,and macrophages)and positively associated with different subsets of T cells,monocytes,and M1 macrophages,among others.Conclusions:This study demonstrates that high BMI1 expression is strongly correlated with immune infiltration and poor prognosis in HCC.Increased expression of BMI1 might thus be a potential mechanism of immune tolerance in this disease.