Concomitant overexpression of mir‐182‐5p and mir‐182‐3p raises the possibility of IL‐17–producing Treg formation in breast cancer by targeting CD3d, ITK, FOXO1, and NFATs: A meta‐analysis and experimental study

T cells are polarized toward regulatory T cells (Tregs) in tumor microenvironment by the shuttling of microRNAs that target T cell–activating signaling pathways. We evaluated the expression of the miR‐182 cluster (miR‐96, 182, and 183) in peripheral blood mononuclear cells (PBMCs) of patients with breast cancer (BC), and T cell polarization by the expression of FOXO1, NFATs, ITK, TCR/CD3 complex, and IL‐2/IL‐2RA. Twenty‐six microRNAs overexpressed in tumor tissues and sera of these patients were extracted by a meta‐analysis. Then, the expression of the miR‐182 cluster was investigated in PBMCs and sera of these patients and correlated with their targets in PBMCs. Finally, miR‐182 was cloned into Jurkat cells to evaluate its effects on T cell polarization. FOXO1, CD3d, ITK, NFATc3, NFATc4, and IL‐2RA were targeted by miR‐182, due to which their expression decreased in PBMCs of patients. Although IL‐6, IL‐17, and TGF‐β increased after miR‐182 transduction, IL‐2 dramatically decreased. We revealed CD4(+)FOXP3(+) T cell differentiation in the miR‐182–transduced group. Although miR‐182 has inhibitory effects on T cells by the inhibition of FOXO1, TCR/CD3 complex, NFATs, and IL‐2/IL‐2RA signaling pathways, it increases FOXP3, TGF‐β, and IL‐17 expression to possibly drive T cell deviation toward the transitional state of IL‐17–producing Tregs and Treg formation in the end.