TMT1A inhibits lung adenocarcinoma progression by suppressing M2 macrophage polarization

The role of thiol methyltransferase 1A (TMT1A) in lung adenocarcinoma (LUAD) progression and the immune microenvironment remains unclear. Analysis of clinical samples and public databases revealed significantly lower TMT1A expression in tumorous LUAD samples compared to non-neoplastic counterparts. Cox regression analysis confirmed TMT1A as an independent prognostic factor for LUAD. Phenotypically, functional assays demonstrated that <i>TMT1A</i> expression inhibited LUAD cell proliferation and migration. Furthermore, single cell transcriptome sequencing analysis showed that TMT1A expression was positively correlated with the immune cells, especially macrophages. Mechanistically, high <i>TMT1A</i> expression was found to inhibit M2 macrophage polarization and downregulate PD-L1 expression in LUAD cells. In co-culture experiments involving LUAD cells and T cells, <i>TMT1A</i> knockdown suppressed T cell activation and reduced IFN-γ secretion. These findings were further validated by <i>in vivo</i> experiments, where <i>TMT1A</i> expression was found to promote CD8⁺ T cell infiltration in LUAD. These findings demonstrated tumor-suppressive functions coupled with its immunomodulatory capacity position TMT1A as a promising therapeutic target for LUAD treatment.