METTL3 is a Potential Prognostic Biomarker in Head and Neck Squamous Cell Carcinoma

Abstract

Background Head and neck squamous cell carcinoma (HNSCC) is a common malignant tumor., and incidence and mortality of HNSCC are relatively high. Most HNSCC patients are diagnosed at an advanced stage and lack specific treatment. There is an urgent need to identify new molecular markers for prognostic evaluation. It is well known that N6-methyladenosine (m6A) RNA modification plays a critical role in a variety of tumors, especially HNSCC. However, the relationship between the m6A “writer”, METTL3, and the prognosis of HNSCC remains unknown. The present study aimed to evaluate the potential roles and prognostic value of METTL3 in HNSCC. Methods A total of 448 HNSCC samples with clinical information obtained from The Cancer Genome Atlas (TCGA) datasets and 72 HNSCC samples from Gene Expression Omnibus (GEO) datasets were analyzed. The expression of METTL3 across cancers was analyzed with the TIMER database. Univariate and multivariate Cox regression analyses were used to determine the independent prognostic factors for HNSCC. The Kaplan–Meier method was used for survival analysis. Differential expression analysis of METTL3-related genes was performed with DESeq2. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted to identify the potential role of METTL3-related genes in HNSCC. The TIMER database was used to analyze the association between METTL3 expression and the infiltration levels of immune cell. Immunohistochemistry was used to verify the relationship between METTL3 expression and immune cells infiltration. Results METTL3 expression was significantly upregulated in HNSCC (P < 0.001), and HNSCC patients had a better prognosis when METTL3 was significantly upregulated. Low METTL3 expression in HNSCC patients over 60 years old was associated with poor prognosis (P = 0.0062) with the most significant result for laryngeal carcinoma patients (P < 0.0001). Additionally, METTL3 expression led to changes in the tumor immune microenvironment. We found that the high expression of METTL3 had a positive correlation with CD4 + T cells and neutrophils but a negative correlation with B cells, CD8 + T cells, macrophages, and dendritic cells. IHC assays further confirmed this conclusion. In addition to oral cancer, METTL3 was positively correlated with CD4 expression in laryngeal and tongue cancers (P < 0.05). Finally, we constructed a prognostic nomogram in HNSCC to predict the individuals’ survival probability by age, stage, T stage, N stage, M stage, and grade. Calibration was performed for the nomogram, and the calibration curves showed that the nomogram-predicted probability matched the observed line for the 1-, 3-, and 5-year survival. Conclusion The present study found that upregulated METTL3 recruits CD4 + T cells around the tumor, reshapes the immune microenvironment and enables prolonged survival. In conclusion, METTL3, as an independent factor affecting the prognosis of HNSCC, may become a novel biomarker for HNSCC, playing a role in regulating the tumor immune response.