Investigating the Role of miR-187-3p in Molecular Apocrine Breast Cancer

Abstract

: Breast cancer (BC) is a health problem that is reported to have the highest incidence and mortality rates of cancer among females worldwide and in Lebanon. Moreover, BC heterogeneity renders it from being diagnosed or treated as a single entity. As such, there has been several attempts to classify BC. The expression of hormonal receptors is one of the methods being used for subtyping BC. These receptors are estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Thus, based on the expression of these receptors, BC is classified into 4 molecular subtypes. The most aggressive subtype is negative for the three receptors and is called triple negative BC (TNBC). TNBC itself is also heterogenous and it overlaps with distinct subtypes, namely Molecular Apocrine (MA) and Luminal Androgen (LAR) BCs. These subtypes which overexpress Androgen receptor (AR) are, even today, still misdiagnosed and poorly treated. The discovery of new biomarkers that can help in differentiating subtypes might serve as a helpful tool. A significant amount of research has proved these micro-RNAs (miRNAs) are dysregulated in different types of cancers including BC, and consequently could be involved in cancer initiation and/or progression. Moreover, some miRNAs exhibit distinct dysregulation patterns across BC subtypes, offering potential diagnostic value. Using publicly available data and in silico analysis done on a cohort of ER-negative tissues, our lab found that miR-187-3p is significantly upregulated in samples classified as MABC compared to non-MABC samples. In addition, miR-187-3p is reported as a key player in the tumorigenesis of several types of cancer by controlling proliferation, invasiveness, migration, and aggressiveness of cancerous cells. Building upon these findings, we investigated the role of miR-187-3p in the tumorigenesis of MABC using in vitro BC cellular models.