BCL2A1 is associated with tumor-associated macrophages and unfavorable prognosis in human gliomas

B-cell lymphoma 2-related protein A1 (BCL2A1) is a member of the BCL-2 family. Previous studies have shown that BCL2A1 is closely related to the tumorigenesis and resistance to chemotherapy of multiple solid tumors, such as breast cancer. However, the expression pattern and potential biological function of BCL2A1 in glioma remain unknown. For the first time, we found that the expression of BCL2A1 was higher in human glioma tissues than in normal brain tissues (NBTs) in both public datasets and an in-house cohort. High BCL2A1 expression was associated with advanced WHO grade, IDH 1/2 wild type and the mesenchymal (ME) subtype, and its overexpression in glioma predicted resistance to temozolomide (TMZ) chemotherapy and unfavorable prognosis. In addition, Gene set enrichment analysis (GSEA), Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that BCL2A1 was significantly correlated with the immune response and immune-related pathways, and BCL2A1 expression was positively correlated with microenvironmental parameters (immune, stromal, and ESTIMATE scores) and macrophage infiltration. Interestingly, bioinformatic prediction and immunohistochemical/immunofluorescence staining analysis revealed that BCL2A1 expression was obviously associated with the tumor-associated macrophages (TAMs) markers CD68 and CCL2. Notably, knockdown of BCL2A1 significantly inhibited cell proliferation of U87 and U251 in vitro, induced smaller tumor size and prolonged survival time of mice in vivo. Co-culture experiments of macrophages and GBM cells showed that BCL2A1 knockdown inhibited macrophage migration. Meanwhile, knockdown of BCL2A1 was associated with low expression of CD68 and CCL2 in intracranial xenograft model. This may suggest that BCL2A1 promotes the progression of glioma and influences the prognosis of patients by participating in TAMs infiltration. In conclusion, these findings suggest that BCL2A1 could serve as a promising prognostic indicator and immunotherapy target in gliomas.