miRNAs as therapeutic targets to counteract triple negative breast cancer

Triple Negative Breast Cancer (TNBC) is a specific subset of breast cancer defined by the loss of Estrogen Receptor (ER), Progesterone Receptor (PR) and Human Epidermal Growth Factor 2 (HER2). Beside these phenotypic features, it is also characterized by a poorer prognosis, compared to the other breast cancer subtypes, due to higher risk of relapse and early metastasis. Currently, no targeted therapy is available, therefore a better understanding of the disease both at a biological and molecular level and the identification of novel targets is essential. MicroRNAs (miRNAs) are small non-coding RNA sequences that modify the gene expression post-transcriptionally, by binding to complementary sequences at the 3’-UTR of mRNAs. In the last decade, they have emerged as important regulators of tumor progression and metastasis by acting either as oncogenic-miRs or oncosuppressor-miRs. In this work, I am going to discuss about three different miRNAs namely miR-4306, miR-22-3p and miR-1290: the first two are oncosupressor-miRs and their poor expression levels promotes proliferation, invasion and metastasis. The third, instead, is involved in radioresistance and blocks pyroptosis, thus having a key role in promoting the tumor growth. Further studies on miRNA-based therapies could lead to the identification of new promising tools to counteract TNBC.