Pan-Cancer Analysis of the Prognostic and Immunological Role of SMG5: A biomarker for cancers

Introduction: SMG5 is involved in tumor cell development and viewed as a potential target for immunotherapy. The purpose of this study was to systematically analyze the expression level, function and prognostic value of SMG5 in pan-cancers. Methods: Differential expression of SMG5 in normal and tumor tissues was analyzed using The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression database (GTEx) data. Survival analysis was performed by Kaplan-Meier (KM) method and Cox risk regression. The relationship between SMG5 expression and lymphocyte abundance, tumor cell immune infiltration level, molecular and immune subtypes, as well as immune checkpoints were analyzed by Tumor-immune system interactions database (TISIDB), Tumor Immune Estimation Resource (TIMER) and Sangerbox databases. The correlation between SMG5 and immune scores was studied using the Estimation of Stromal and Immune cells in Malignant Tumours using Expression data (ESTIMATE) algorithm. Further, drug sensitivity analysis of SMG5 with low-grade glioma (LGG) was conducted using the CellMiner database. Results: SMG5 was highly expressed in 23 tumors and only had a significant impact on the prognosis of patients with LGG only. In addition, in tumor microenvironment and tumor immune analysis, we found that the level of immune infiltration, tumor mutational load (TMB), microsatellite instability (MSI) and immune checkpoints of LGG were significantly correlated with SMG5 expression. Furthermore, SMG5 was significantly associated with immune scores, stromal scores and sensitivity of some drugs in LGG. Conclusion: SMG5 is differentially expressed in several cancers and is significantly associated with prognosis, immune microenvironment and immune checkpoints in LGG patients. Therefore, SMG5 could be a potential pan-cancer biomarker and an immunotherapeutic target for LGG.