LncRNA-MEG3 Suppresses the Proliferation and Invasion of Melanoma by Regulating CYLD Expression Mediated by Sponging miR-499-5p.

Jianwen Long,Xianming Pi

doi:10.1155/2018/2086564

Abstract

The abnormal expression of long noncoding RNA- (lncRNA-) MEG3 was clearly identified in a number of malignant tumors, but the specific function of MEG3 remains unknown in malignant melanoma until now. The research attempts to explore the effects of MEG3 on the growth and metastasis of malignant melanoma. MEG3 and miR-499-5p expression were determined by qRT-PCR method. Western blotting assay was applied to detect protein expression. Luciferase reporter assay was used to assess the correlation between MEG3 and miR-499-5p and between CYLD and miR-499-5p. Cell growth, cell cycle, and cell apoptosis were examined by CCK-8 assay, EdU assay, and flow cytometry assay, respectively. The invasion ability of melanoma cells was investigated by wound-healing and Transwell assays. The effect of MEG3 on growth of melanoma in vivo and cell chemosensitivity was detected by xenograft animal model and CCK-8 assay. As a result, the expression of MEG3 was decreased in melanoma tissues and cell lines. The level of MEG3 was significantly associated with poor prognosis. MEG3 could bind to miR-499-5p and CYLD mRNA contained a binding site of miR-499-5p. The expression of CYLD was reduced and the level of miR-499-5p was elevated in melanoma tissues and cell lines. Luciferase reporter assay and western blot assay confirmed that MEG3 regulated the expression of CYLD by sponging miR-499-5p. Functionally, upregulation of MEG3 inhibited melanoma cell proliferation, invasion, and migration, enhanced melanoma cell apoptosis, arrested melanoma cell cycle, and regulated the expression of E-cadherin, N-cadherin, and cyclin D1 by regulating CYLD expression mediated by sponging miR-499-5p. Importantly, overexpression of MEG3 suppressed the growth of xenograft tumor and improved chemotherapy sensitivity of A375 cells to cisplatin and 5-FU treatment. In conclusion, MEG3 has a crucial function in the tumorigenesis of melanoma, and MEG3 may be a potential therapeutic target in the treatment of melanoma.

Highlights

Malignant melanoma originating from melanocytes is an aggressive skin cancer which is listed as the seventh most frequent malignant tumor in females and the fifth most frequent malignant tumor in males worldwide [1]
The Expression of Maternally expressed gene 3 (MEG3) and CYLD Was Decreased, but the Expression of miR-499-5p Was Increased in Melanoma Specimens and Cell Lines. qRT-PCR and western blot assay were applied for detecting the expression of MEG3, miR-499-5p, and CYLD
It was identified that the level of MEG3 and CYLD was significantly decreased, but the expression of miR-4995p was dramatically increased in melanoma tissues and cell lines compared with paired nontumor tissues or HEMa-LP cells (Figure 1)

Summary

Introduction

Malignant melanoma originating from melanocytes is an aggressive skin cancer which is listed as the seventh most frequent malignant tumor in females and the fifth most frequent malignant tumor in males worldwide [1]. The incidence of melanoma has been remarkably increasing in recent years, and the progression and metastasis of melanoma are extremely rapid [2, 3]. Increasing evidences emphasized that lncRNAs played essential roles in regulating numerous biological activities including cell proliferation [4], cell autophagy [5], and tumor metastasis [6]. Expressed gene 3 (MEG3) is positioned on human chromosome 14q32.3 and encoded by a maternally imprinted gene [8]. Recent researches have demonstrated that MEG3 was involved in the tumorigenesis of diverse malignant tumors. Overexpression of MEG3 suppressed significantly chronic myeloid leukemia cell growth and invasion by regulating the expression of miR-184 [9], MEG3 inhibited breast cancer cell growth and metastasis by blocking AKT pathway [10], and MEG3 limited

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Conclusion