Comprehensive analysis of m6A subtype classification for immune microenvironment of pituitary adenomas

•We first identified two novel m6A subtypes in pituitary adenomas (PAs) based on the m6A regulator gene set. These subtypes exhibit distinct characteristics in tumor immune microenvironment, suggesting diverse responses to immunotherapy.•YTHDF2 showed a correlation with elevated levels of M2 macrophages and PD-L1 expression, making it a promising biomarker for immunotherapy and a potential molecular target in PAs.•A clinically accessible polygenic nomogram model was constructed to predict the m6A subtype classification in PAs. This nomogram demonstrated excellent predictive performance and can aid in clinical decision-making. N6-methyladenosine (m6A) RNA methylation and tumor immune microenvironment (IME) have an essential role in tumor development. However, their relationships in pituitary adenomas (PAs) remains unclear. PA datasets from the Gene Expression Omnibus (GEO) and European Bioinformatics Institute (EMBL-EBI) were used. We utilized hierarchical clustering algorithms based on the m6A regulator gene set to identify m6A subtypes. ESTIMATE and CIBERSORT algorithms were applied to explore the compositions of stromal and immune cells. A nomogram model was constructed for the prediction of m6A subtypes in PAs. Immunohistochemistry and multiplex immunofluorescence staining were used to analyze the expression level of m6A regulator YTHDF2 in relation to M2 macrophages and immune checkpoints in PAs. We concluded the IME landscape of m6A subtype classification and characterized two emerging m6A subtypes. Different IME between these two m6A subtypes were identified. Simultaneously, a polygenic nomogram model was constructed for predicting m6A subtype classification, with excellent predictive performance (training set, AUC = 0.984; validation set, AUC = 0.986). YTHDF2 was highly expressed in PAs and accompanied by upregulated M2 macrophages and expression of PD-L1. We proposed two novel m6A subtypes in PAs for the first time and constructed a reliable and clinically accessible nomogram model for them. Meanwhile, YTHDF2 was first identified as a promising biomarker for immunotherapy and potential molecular target in PAs.