Overexpression of miR-490-5p/miR-490-3p Potentially Induces IL-17-Producing T Cells in Patients With Breast Cancer.

Objective: Breast cancer (BC) is the most prevalent female cancer globally and this is also true in Iranian women. Alteration in circulating microRNAs affects the fate of immune cells, affecting immunological response to neoplasia. Materials and Methods: We investigated the expression of miR-490-5p and miR-490-3p in peripheral blood mononuclear cells (PBMCs) and plasma of patients with BC. Moreover, the correlation of these microRNAs with the expression levels of CD3d, interleukin 2 (IL-2), IL-2 receptor chain alpha (IL-2RA), forkhead box O1 (FOXO1) and nuclear factor of activated T cells 5 (NFAT5) were investigated. Results: Two groups, including 42 patients with BC, aged 22-75 years with stage I, II, III disease without administration of immunosuppressive chemotherapy regimens/radiotherapy and 40 healthy controls aged 27-70 years, participated. Overexpression and higher circulation levels of miR-490-5p and miR-490-3p were found in the patients with consequent down-regulation of all targets investigated in PBMCs. Furthermore, there was a significant negative correlation between the overexpression of these microRNAs and a reduction in levels of CD3d, IL-2, and IL-2RA in patients with BC. Conclusion: These results suggest that down-regulation of the target genes by miR-490 may predispose and facilitate the production of Th17 lymphocytes and IL-17-producing Tregs. The variation in miR-490-5p/-3p and the investigated targets in the PBMCs of BC patients may be used as non-invasive diagnostic markers.