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MicroRNA mediated aberrant gene regulation has been implicated in several diseases including cancer. Recent research has highlighted the role of epigenetic modulation of the complex process of breast cancer metastasis by miRNAs. miRNAs play a crucial role in the process of metastatic evolution by facilitating alterations in the phenotype of tumor cells and the tumor microenvironment that promote this process. They act as critical determinants of the multi-step progression starting from carcinogenesis all the way to organotropism. In this review, we focus on the current understanding of the compelling role of miRNAs in breast cancer metastasis., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: The study assessed the epigenetic regulation and the role of microRNA (miR) expression in locally advanced triple negative breast cancers (TNBC) and comparison with the clinico-pathological variables and survival., Methods: Fifty patients of locally advanced TNBC during the period 2011-2013 were included. Expression level of test microRNA (miR-182 and miR-18a) was determined using Taqman quantitative Real time polymerase chain reaction (qRT-PCR) from formalin fixed paraffin embedded biopsy blocks. Clinical and demographic information and survival data was retrieved from the Hospital medical records., Results: An improved clinical complete response (cCR) was observed in patients with age ≥ 45 years (80%), premenopausal status (70%), tumor size < 6 cms (80%), nodal status N0-N1 (95%) and grade II-III tumor (80%). A statistically significant correlation was observed on comparison of cCR with menopausal status (p-value 0.020), T category (p-value 0.018) and the clinical nodal status (p-value 0.003). pCR also correlated with clinical nodal status (p-value 0.008). Epigenetically, miR-18a under expression (< 8.84) was most commonly associated with tumor size < 6 cms (76.7%), clinical nodal status N0-N1 (90%), cCR (60%) and pCR (53.3%). A similar trend was observed with miR-182. Statistical significance was observed with T category (p-values 0.003 and 0.004), clinical nodal status (p-values 0.001 and 0.001), clinical response (p-values 0.002 and 0.002) and pathological response (p-values 0.007 and 0.006) with respect to miR-18a and miR-182, respectively. Also, the menopausal status significantly correlated with the miR-182 expression (p-value 0.009). miR-182 overexpression (≥ 6.32) was not observed in any of the postmenopausal patients. A univariate cox proportional hazard regression model also showed statistical interactions (p-values <0.004)., Conclusion: miR-182 and miR-18a overexpression correlates with worse clinical and pathological tumor characteristics in locally advanced TNBC and hence could be used to predict the outcomes and prognosis in these patients., Competing Interests: The authors have declared that no competing interests exist.