Expression patterns of microRNA-218 and its potential functions by targeting CIP2A and BMI1 genes in melanoma.

Abstract

Melanoma is the most aggressive skin cancer, and it is typically resistant or rapidly develops resistance to a variety of chemotherapeutic agents. microRNAs (miRNAs) play a part in the occurrence and development of malignant melanoma. In this study, we analyzed the miR-218 expression level in melanoma patients and cell lines and observed alterations in proliferation, cell cycle, migration, and invasion by increasing miR-218 expression in melanoma cell lines. We also performed bioinformatic analyses using TargetScan and miRanda and cloned both the wild-type and mutant versions of the human cancerous inhibitor of protein phosphatase 2A (CIP2A) and B lymphoma Mo-MLV insertion region 1 (BMI1) 3'-UTR fragments into the pmirGLO reporter vector. We then used the Dual-Luciferase assay system, quantitative real-time RT-PCR (qRT-PCR), and Western blot analysis to determine that miR-218 targeted the 3'-UTR of the oncogenes CIP2A and BMI1 and thus regulated the biological process of melanoma. We further demonstrated that CIP2A and BMI1 knockdown phenocopies miR-218 overexpression. In conclusion, our findings have shown that miR-218 is downregulated in melanoma. By targeting CIP2A and BMI1, miR-218 regulates the proliferation, migration, and invasion of the melanoma cell lines A375 and SK-MEL-2, indicating that miR-218 plays a pivotal role in melanoma development.