Tumor suppressor microRNA-204-5p regulates growth, metastasis, and immune microenvironment remodeling in breast cancer

Various microRNAs (miRNAs) play critical roles in the development and progression of solid tumors. In this study, we describe the role of miR-204-5p in limiting growth and progression of breast cancer. In breast cancer tissues, miR-204-5p was significantly downregulated compared to normal breast tissues, and its expression levels were associated with increased survival outcome in breast cancer patients. Overexpression of miR-204-5p inhibited viability, proliferation, and migration capacity in human and murine breast cancer cells. Additionally, miR-204-5p overexpression resulted in a significant alteration in metabolic properties of cancer cells and suppression of tumor growth and metastasis in mouse breast cancer models. The association between miR-204-5p expression and clinical outcomes of breast cancer patients showed a non-linear pattern that was reproduced in experimental assays of cancer cell behavior and metastatic capacities. Transcriptome and proteomic analysis revealed that various cancer-related pathways including PI3K/Akt and tumor immune interactions were significantly associated with miR-204-5p expression. PIK3CB, a major regulator of PI3K/Akt pathway, was a direct target for miR-204-5p, and the association between PIK3CB-related PI3K/Akt signaling and miR-204-5p was most evident in the basal subtype. The sensitivity of breast cancer cells to various anti-cancer drugs including PIK3CB inhibitors was significantly affected by miR-204-5p expression. Additionally, miR-204-5p regulated expression of key cytokines in tumor cells and reprogrammed the immune microenvironment by shifting myeloid and lymphocyte populations. These data demonstrate both cell-autonomous and non-cell-autonomous impacts of tumor suppressor miR-204-5p in breast cancer progression and metastasis.

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