A Pan-Cancer Analysis of the BIRC Gene Family and Its Association with Prognosis, Tumor Microenvironment, and Therapeutic Targets

The inhibitors of apoptosis protein (IAP)/baculoviral IAP repeat containing (BIRC) gene families are necessary for cell protection, and most of these genes act as endogenous inhibitors of apoptosis. In some cancers, the over-expression of the BIRC gene is associated with cancer progression, multidrug resistance, poor prognosis and short-term survival. In this study, we aimed to assess the effect of the BIRC family in pan-cancer. We downloaded transcriptome and clinical data from 33 types of TCGA tumor samples and adjacent tissues. Then, the expression characteristics of IAP family members BIRC2, BIRC3, BIRC5, BIRC6 and BIRC7 in pan-cancer were analyzed. R packet and Cox regression were used to analyze the clinical correlation. In addition, the transcription level of BIRC and immune subtypes, stem cells, immune tumor microenvironment (TME) and drug sensitivity were analyzed by multidimensional correlation. Our studies have shown that the expression of IAP family members BIRC2, BIRC3, BIRC5, BIRC6, and BIRC7 is different in different tumor types, and the heterogeneity is obvious in cancers. Overall, our analysis showed that BIRC2, BIRC3, BIRC6, and BIRC7 were mainly down-regulated in tumors, whereas BIRC5 was mainly up-regulated in tumors. The expression of IAP family members is related to the overall survival of patients. However, the direction of the association varies depending on specific IAP subtypes and specific types of cancer. More specifically, BIRC5 is mainly related to poor prognosis. The rest of the IAP family showed either a survival advantage or a survival disadvantage, depending on the type of cancer. In addition, BIRC2, BIRC3, BIRC5, BIRC6 and BIRC7 were significantly correlated with immune infiltration subtypes and had different degrees of correlation with the degree of interstitial cell infiltration and tumor cell dryness. Finally, our study revealed that BIRC2, BIRC5, and BIRC7 genes may be related to drug resistance of tumor cells. Our systematic analysis of (IAP) gene expression and its relationship with immune infiltration, TME, cancer stem cells, drug sensitivity and prognosis of cancer patients highlights the need to study IAP family members as separate entities in each specific cancer type. In addition, our study confirmed that IAP family genes are promising therapeutic targets for cancer and potential prognostic indicators for clinical application, although further laboratory verification is needed.