miR-514a regulates the tumour suppressor NF1 and modulates BRAFi sensitivity in melanoma

Abstract

To identify 'melanoma-specific' microRNAs (miRNAs) we used an unbiased microRNA profiling approach to comprehensively study cutaneous melanoma in relation to other solid malignancies, which revealed 233 differentially expressed (≥ 2 fold, p < 0.05) miRNAs. Among the top 20 most significantly different miRNAs was hsa-miR-514a-3p. miR-514a is a member of a cluster of miRNAs (miR-506-514) involved in initiating melanocyte transformation and promotion of melanoma growth.We found miR-514a was expressed in 38/55 (69%) melanoma cell lines but in only 1/34 (3%) other solid cancers. To identify miR-514a regulated targets we conducted a miR-514a-mRNA 'pull-down' experiment, which revealed hundreds of genes, including: CTNNB1, CDK2, MC1R, and NF1, previously associated with melanoma. NF1 was selected for functional validation because of its recent implication in acquired resistance to BRAFV600E-targeted therapy. Luciferase-reporter assays confirmed NF1 as a direct target of miR-514a and over-expression of miR-514a in melanoma cell lines inhibited NF1 expression, which correlated with increased survival of BRAFV600E cells treated with PLX4032. These data provide another mechanism for the dysregulation of the MAPK pathway which may contribute to the profound resistance associated with current RAF-targeted therapies.

Scan_Tcga Tools for Integrated Epigenomic and Transcriptomic Analysis of Tumor Subgroups

“…We observed that a group of miRNAs were consistently expressed either at a high level (e.g., let7a/b, miR-21 and miR-30d, Figure 6) or a low level (e.g., miR-34b, miR-26a, miR-137, miR-18b). These results are consistent with previous reports of deregulation of future science group Methodology Chatterjee, Stockwell, Rodger, Parry & Eccles these miRNAs in melanoma [43][44][45][46][47][48]. Furthermore, a group of miRNA showed distinct expression profiles between primary and melanoma patients.…”

microRNA-7-5p inhibits melanoma cell proliferation and metastasis by suppressing RelA/NF-κB

“…Our expression array data indicate that miR-7-5p functions to regulate large networks of genes in melanoma, and our network analysis supports the concept of regulation via “hub genes”, which includes RelA, a transcriptional regulator that itself regulates expression of many other genes, and hence altering miR-7-5p expression produces a significant “flow on” effect in terms of broadly altering gene expression [62]. We found that downregulation of RelA by miR-7-5p resulted in reduced expression of various canonical targets of NF-κB, including IL-1β, thus providing additional evidence for the indirect inhibition of broad transcriptional networks.…”

“…Further, we and others have shown that miR-7-5p is capable of sensitizing other resistant tumor types to targeted therapies, such as the EGFR tyrosine kinase inhibitor erlotinib [61]. In support of this concept, Stark et al have shown that miR-514a modulates BRAF inhibitor sensitivity in melanoma through its regulation of the tumor suppressor NF1 [62]. In addition, miR-7-5p could potentially augment the anti-melanoma immune response, by blocking expression of immunosuppressive cytokines, such as IL-6 [63].…”

miR‑514a‑3p functions as a tumor suppressor in renal cell carcinoma

“…miR-514a-3p (previously known as miR-514), located on chrXq27.3, has been demonstrated to be abnormally expressed in melanoma and metastatic RCC (25,26). In melanoma, Stark et al observed that miR-514a-3p negatively regulated nuclear factor 1 (NF1) and cyclin-dependent kinase 2 (CDK2) (26).…”

“…In melanoma, Stark et al observed that miR-514a-3p negatively regulated nuclear factor 1 (NF1) and cyclin-dependent kinase 2 (CDK2) (26). Wotschofsky et al assessed the expression of miR-514a-3p in 111 RCC patients (22 cases with metastases and 89 without) and the results revealed that miR-514a-3p was further downregulated in metastatic RCC compared with non-metastatic RCC tissues (25).…”