The Prognostic Significance of Immune-Related Metabolic Enzyme MTHFD2 in Head and Neck Squamous Cell Carcinoma

Metabolic dysregulation has emerged as a crucial determinant of the clinical responses to immunotherapy. The aim of this study was to determine the clinical significance of the candidate immune-related metabolic enzymes (IRMEs) methylenetetrahydrofolate dehydrogenase (NADP+ dependent) 2 (MTHFD2) in head and neck squamous cell carcinoma (HNSCC). The gene expression profile of HNSCC cohort and the corresponding clinical information were downloaded from The Cancer Genome Atlas (TCGA). The differentially expressed IRMEs were identified, and then, the prognosis-associated IRMEs were revealed by univariate cox regression analysis. The prognostic significance of MTHFD2 in HNSCC as well as the association between MTHFD2 and immune cell infiltration were further analyzed. A total of 121 significantly altered IRMEs were identified between HNSCC and normal tissues, and 21 IRMEs were found to be strongly associated with overall survival of HNSCC. Upregulation of MTHFD2 was positively correlated with adverse clinicopathological factors in TCGA HNSCC cohort, which was further validated with our own cohort using immunohistochemical analysis. Interestingly, bioinformatic analysis further revealed that increased MTHFD2 expression was negatively associated with NK cells activation, while positively correlated with mast cells activation. In conclusion, MTHFD2 overexpression is closely correlated with unfavorable prognosis of HNSCC, and it might play an important role in modulating the tumor immune microenvironment.