Pan-cancer analysis of DEFB1 as a candidate prognostic biomarker and associated with immune infiltration

Despite many cell or animal experiments that support the close association of DEFB1 with cancer, no comprehensive pan-cancer analysis has been reported. The present research initially investigated its role in many cancers using The Cancer Genome Atlas (TCGA) data. To analyze DEFB1 in cancers, we utilized The Human Protein Atlas (HPA), TCGA, Genotype-Tissue Expression (GTEx), Tumor Immune Estimation Resource 2.0 (TIMER2.0), University of Alabama at Birmingham Cancer data analysis Portal (UALCAN), Gene Expression Profiling Interactive Analysis 2 (GEPIA2), and cBioPortal databases. The visualization of data was primarily accomplished through the use of the R language. Most cancers and their adjacent normal tissues exhibit differential expression of DEFB1.The prognosis of distinct cancers was notably impacted by DEFB1. High DEFB1 expression could induce a poorer overall survival (OS) in the lung adenocarcinoma (LUAD)and pancreatic adenocarcinoma (PAAD) cohorts; in contrast, it could lead to a significantly higher OS in the head-neck squamous cell carcinoma (HNSC) cohort ( P  < 0.05). Moreover, high DEFB1 expression could result in a poor disease-free survival (DFS) in the cholangiocarcinoma (CHOL) cohort ( P  < 0.05). Notably, Liver hepatocellular carcinoma (LIHC)samples demonstrated the highest DEFB1 mutation frequency among all cancer types. Furthermore, there was a close relationship of DEFB1 expression with the extent of cancer-associated fibroblast infiltration in LIHC, thyroid carcinoma (THCA), colon adenocarcinoma (COAD), head-neck squamous cell carcinoma (HNSC), and stomach adenocarcinoma (STAD), while neutrophil infiltration was revealed in other malignancies, including bladder carcinoma (BLCA), diffuse large B-cell (DLBC), lung squamous cell carcinoma (LUSC), PAAD, as well as uterine corpus endometrial carcinoma (UCEC). This initial pan-cancer research can help comprehensively understand the carcinogenesis of DEFB1 in many malignancies.