Comprehensive Analysis of Prognostic and Immune Infiltrates for RAD51 in Human Breast Cancer

Breast cancer is the number one cause of death from malignant tumors in women. The expression level of RAD51 in malignant tumors is significantly higher than normal tissues and is closely related to tumor progression, immunosuppression, resistance to radiotherapy and chemotherapy, and prognosis. We assess the role of RAD51 in breast cancer via bioinformatics analysis. The expression of RAD51 in breast cancer and its relationship with clinicopathology were analyzed by TCGA, GEPIA2, TIMER database; univariable survival and multivariate Cox analysis were used to compare several clinical characteristics with survival. We also explored the correlation between RAD51 and cancer immune infiltrates cell level using cibersort and TIMER database. In addition, we used STRING, GeneMANIA, and GSEA analysis to explore RAD51 upstream and downstream regulatory proteins, RAD51 family (RAD51, RAD51B, RAD51C, RAD51D, XRCC2, XRCC3, and DMC1) gene interaction network map, and RAD51 enrichment analysis. Finally, RAD51 genetic variation, functional enrichment analysis of adjacent genes, and RAD51 immunohistochemical expression in breast cancer tissues were observed by cBioPortal, HPA database. RAD51 expression in breast cancer, lung adenocarcinoma, lung squamous cell carcinoma, gastric cancer, colon adenocarcinoma, and endometrial cancer are higher than normal tissues. In breast cancer patients, the expression of RAD51 was significantly different due to age, T stage, and tumor stage. The overall survival of RAD51 low-expression patients were better than high-expression patients (P = 0.018). Compared with the RAD51 low expression group, the M0 and M1 of activated CD4+ T cells, Tfh cells, Treg cells, and macrophages significantly increased in the high expression group; the initial B cells, resting CD4+ T cells, resting NK cells, resting dendritic cells, activated dendritic cells, resting mast cells, neutrophils significantly decreased; and RAD51 expression was significantly positively correlated with infiltration of B cells, CD4+ T cells, CD8/CD4+ T cells, neutrophils, and dendritic cells. STRING analysis showed the interaction between RAD51 and MND1, RAD52, BRCA2, CHEK1, BLM, EXO1, BRCA1, BARD1, MUS81, ATM. Matrix transcription factor pathway, cell cycle pathway, DNA replication pathway, and P53 signaling pathway were identified as the differentially enriched pathway in KEGG. RAD51 is a prognostic biomarker and correlated with immune infiltrates in breast cancer.