Study of the mechanisms and functions of miR-524-5p and miR-596 in melanoma cells

• Main Authors: Szu-Mam Liu, 劉思蔓
• Other Authors: Nianhan Ma
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/57582867581480706291

博士 === 國立中央大學 === 生醫科學與工程學系 === 105 === MAPK/ERK pathway is deregulated in one-third of all human cancers, including melanoma. MicroRNAs have become an attractive strategy to apply in cancer therapy because that they are endogenous products and can repress several targets in a specific oncogenic signaling pathway. Previous results from microRNA microarray identified 22 candidate MAPK-related microRNAs in melanoma cells. However, the possible tumor-suppressive activities and clinic pathological characteristics of candidate microRNAs in melanoma had poorly evaluated and how microRNAs involved in the oncogenic signaling pathway remains unclear. Among 22 candidates, we narrowed down nine microRNAs (miR-192-3p, miR-218-2-3p, miR-518d-5p, miR-518f-5p, miR-520e, miR-524-5p, miR-567, miR-592 and miR-596) are linked to melanoma by GEO database analysis. We further found that all of them can control the melanoma cell growth and migration with different efficiency except miR-218-2-3p and miR-592. In further investigation, we delved into the mechanism of miR-524-5p and miR-596. miR-524-5p represses in MAPK signaling pathway through regulating the levels of BRAF and ERK2. Since BRAF and ERK2 are the main components of MAPK signaling, the overexpression of miR-524-5p effectively inhibits MAPK/ERK signaling, tumor proliferation, and melanoma cell migration. Another potential microRNA, expression of miR-596, is lower in melanoma than in nevi tissues. In addition, miR-596 overexpression effectively inhibits MAPK/ERK signaling, melanoma cell proliferation, migration, and invasion as well as increases cell apoptosis in vitro. Our novel findings showed that miR-596 not only negatively regulates the MAPK/ERK signaling pathway via the MEK1 3’ untranslated region (UTR) but also increases apoptosis via the MCL1 and BCL2L1 3’UTRs. This is the first finding illustrating that miR-596 is an important tumor-suppressive microRNA that can regulate both the survival and death of melanoma. In microRNA application, combinatorial microRNA therapeutics is a new frontier in gene therapy that has the ability to overcome the challenges by targeting multiple components of key oncogenic pathways. The issue of microRNA combination was rarely investigated in melanoma cells. In our preliminary data indicate that combination of miR-524-5p and miR-596 did not show a synergistic but lightly additive effect in melanoma cells. These results from my research studies should provide a research resource to further elucidate the regulatory roles of microRNAs in MAPK signaling pathway.