Pan-cancer analysis of the glycoprotein - associated gene B4GALNT4  with prognositc value and immunological role in malignant tumors

Abstract Background The beta-1,4-N-acetyl-galactosaminyltransferase 4 (B4GALNT4) gene, encoding glycosyltransferase is involved in tumor-associated glycoprotein biosynthesis in different cancer types, which influences cell proliferation, migration, invasion and metastasis. However, the correlation between the expression of B4GALNT4 and the pan-cancers prognosis, immune infiltration, and mutation of tumor-related gene was under investigated. Methods The expression of B4GALNT4 was analyzed using the data from The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), Tumor Immune Evaluation Resource 2 (TIMER2), Gene Expression Profiling Interactive Analysis 2 (GEPIA2), Search Tool for the Retrieval of Interacting Genes/Proteins (STRING), and cBioPortal databases. Human pan-cancer analysis of the association of B4GALNT4 expression with survival prognosis and pathological stage was also performed. Pearson correlation analysis was utilized to determine the potential relationship between B4GALNT4 expression with tumor immune infiltration, tumor neoantigens and immune checkpoint gene expression. Mutational features of the B4GALNT4 gene were further analyzed, including its expression patterns in relation to tumor mutational burden (TMB), microsatellite instability (MSI) and DNA methyltransferase (DNMT). Finally, we investigated the relationship between B4GALNT4-binding proteins and genes correlated with B4GALNT4 expression. Immunohistochemical staining was performed to validate B4GALNT4 protein expression in pan-cancer tissues. Results Data from this study showed that the expression of B4GANLT4 was significantly up regulated in most cancers. Immunohistochemical staining of B4GANLT4 in different cancer tissues also validated this finding. B4GANLT4 expression was positively correlated with poor prognosis of patients, specifically, overall survival (OS) in five cancer types and disease-free survival (DFS) in four cancer types. Immune infiltration analysis revealed a significant negative association of B4GALNT4 expression with different immune infiltration cell populations in glioblastoma multiforme (GBM), low-grade glioma (LGG), and lung squamous cell carcinoma (LUSC), which was further validated with The ESTIMATE algorithm. Increased B4GALNT4 expression and immune neoantigen were strongly positively correlated in rectum adenocarcinoma (READ) and head-and-neck squamous cell carcinoma (HNSC), and conversely, negatively correlated in uterine corpus endometrial carcinoma (UCEC) and thyroid carcinoma (THCA). Additionally, correlation of B4GALNT4 expression with immune checkpoint genes, TMB, MSI, and DNMT was observed across all tumors of TCGA. An intersection analysis of the B4GALNT4-binding proteins and B4GALNT4-correlated genes revealed that BRSK2 and TTYH1 were the intersecting genes of the two sets. Conclusion High expression of B4GALNT4 is associated with poor prognosis and advanced pathological stages in most cancer types, in particular, kidney renal clear cell carcinoma (KIRC), and negatively correlated with immune infiltration levels and the immune checkpoint markers in GBM, LGG and LUSC. Our results support the potential utility of B4GALNT4 as a pan-cancer prognostic prediction tool and novel biomarker of the immunotherapy response.