miR-193b represses cell proliferation and regulates cyclin D1 in melanoma: benign nevi and metastatic melanoma

Cutaneous melanoma is an increasingly common form of skin cancer. The molecular mechanisms regulating melanoma progression are not completely understood. We speculated that specific miRNAs may be involved in melanoma development. We compared the miRNA expression profiles of benign nevi and metastatic melanomas. Unsupervised hierarchical clustering demonstrated a distinct miRNA expression pattern in metastatic melanomas compared to nevi. We identified miRNAs that were differentially expressed in melanoma. Notably, miR-193b was significantly down-regulated in the melanoma tissue examined. Using functional studies we demonstrated that over-expression of miR-193b significantly reduced melanoma cell proliferation, and arrested cell at G1 phase. Further gene expression analysis revealed that miR-193b regulated targets involved in cell cycle. Cyclin D1 was down-regulated by miR-193b at both the mRNA and protein level. This is the first study to show that the miR-193b may reduce cell proliferation by directly repressing cyclin D1. Overall, our study suggests that miRNAs are dysregulated in metastatic melanoma, and that miR-193b may play an important role in melanoma. 8 benign nevi and 8 metastatic melanoma tissue samples were profiled by Agilent MicroRNA Microarray (V1.5).

皮肤黑色素瘤（cutaneous melanoma）是一类发病率持续升高的皮肤恶性肿瘤。目前，调控黑色素瘤进展的分子机制尚未完全明晰。我们推测特定微小RNA（miRNA）可能参与黑色素瘤的发生与发展进程。本研究对比了良性痣与转移性黑色素瘤的微小RNA表达谱。无监督层次聚类分析结果显示，相较于良性痣组织，转移性黑色素瘤组织具备独特的微小RNA表达模式。我们筛选得到了在黑色素瘤中差异表达的微小RNA，其中miR-193b在受试黑色素瘤组织中显著下调。通过功能学实验，我们证实过表达miR-193b可显著抑制黑色素瘤细胞增殖，并将细胞周期阻滞于G1期。进一步的基因表达分析揭示，miR-193b的靶基因参与细胞周期调控；细胞周期蛋白D1（Cyclin D1）的mRNA与蛋白表达水平均被miR-193b下调。本研究首次表明，miR-193b可通过直接抑制细胞周期蛋白D1的表达，降低细胞增殖能力。综上，本研究提示转移性黑色素瘤中存在微小RNA表达失调，且miR-193b可能在黑色素瘤发生发展中发挥重要作用。本研究采用安捷伦微小RNA微阵列（V1.5版本），对8例良性痣组织与8例转移性黑色素瘤组织的微小RNA表达谱进行了检测。