Neuro-Oncology Advances, 2021
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Abstract Background Glioblastoma is the most common adult primary brain tumor with near universal fatality. Major histocompatibility complex (MHC) class-I molecules are important mediators of CD8 activation and can be downregulated by cancer cells to escape immune surveillance. MR1 is a non-classical MHC-I like molecule responsible for the activation of a subset of T cells. Although high levels of MR1 expression should enhance cancer cell recognition, various tumors demonstrate MR1 overexpression with unknown implications. Here, we study the role of MR1 in glioma. Methods Using multi-omics data from TCGA, we studied MR1 expression patterns and its impact on survival for various solid tumors. In glioma specifically, we validated MR1 expression by histology, elucidate transcriptomic profiles of MR1 high vs low gliomas. To understand MR1 expression we analyzed methylation status of the MR1 gene, and MR1 gene related transcription factor expression. Results MR1 is overexpressed in all grades of glioma and many other solid cancers. However, only in glioma, MR1 overexpression correlated with poor overall survival and demonstrated global dysregulation of many immune related genes in an MR1-dependent manner. MR1 overexpression correlated with decreased MR1 gene methylation and upregulation of predicted MR1 promoter binding TFs, implying MR1 gene methylation might regulate MR1 expression in glioma. Conclusion Our in-silico analysis show that MR1 expression is a predictor of clinical outcome in glioma patients and is potentially regulated at the epigenetic level, resulting in immune related genes dysregulation. These findings need to be validated using independent in vitro and in vivo functional studies.