New prognostic biomarker CMTM3 in low grade glioma and its immune infiltration

Background: The CKLF-like MARVEL transmembrane domain-containing 3 (CMTM3) is differentially expressed in a variety of tumors and closely related to tumor occurrence and progression. The expression of CMTM3 was significantly elevated in glioma compared with normal brain tissue, to explore the potential function of CMTM3 in the prognosis and immune infiltration of glioma has certain clinical significance. Methods: The tumor data in this study were derived from the sequencing data of various tumors in The Cancer Genome Atlas (TCGA) database. Low-grade glioma (LGG) data in the TCGA database include sequencing and clinical data. Clinical data mainly include survival time, survival outcome, age, WHO classification and other information. Sequencing data for normal tissues were obtained from the Genotype Tissue Expression (GTEx) database. Statistical analyses were mainly performed using bioinformatics tools and the corresponding R software (version 3.6.3). The Mann-Whitney U test (Wilcoxon rank sum test) was used to compare the expression differences between the tumor group and the normal group. Survival analysis was conducted using log-rank test to compare whether the overall survival (OS) time was statistically different between the CMTM3 high and low expression groups. The Tumor Immunity Estimation Resource (TIMER) database was used for immune infiltration analysis. Results: The results showed that the expression of CMTM3 in World Health Organization (WHO) II and WHO III gliomas was significantly higher than that of normal tissues (P<0.05). Glioma with high CMTM3 expression showed a lower overall survival (OS) (P<0.05). Gene enrichment analysis showed that CMTM3 was significantly enriched in 4 pathways (FDR <0.25, P<0.05). A high correlation was detected between CMTM3 and a variety of immune cells. CMTM3 is highly correlated with macrophages (r=0.536, P=1.31e-36), dendritic cells (r=0.546, P=2.85e-38), CD4+ T cells (r=0.517, P=6.17e-34). Conclusions: The CMTM3 gene can be used as a potential prognostic marker for WHO grade II and WHO grade III glioma, is related to the immune infiltration in glioma microenvironment, and may became a new immunotherapy target.