MicroRNA miR-125b controls melanoma progression by direct regulation of c-Jun protein expression
MicroRNA miR-125b controls melanoma progression by direct regulation of c-Jun protein expression
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DOI：
10.1038/onc.2012.307
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发表时间：
2013-06-13
期刊：
影响因子：
8
通讯作者：
Bosserhoff, A-K
中科院分区：
文献类型：
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作者：
Kappelmann, M.;Kuphal, S.;Bosserhoff, A-K
恶性黑色素瘤发生和发展过程中的一个基本事件是癌症相关转录因子的解除调控。我们最近发现，c-jun是黑色素瘤肿瘤进展的主要调节因子，因此是这种疾病的AP-1转录因子家族中最重要的成员。有趣的是，我们发现c-jun的表达在转录后水平上受到调控，因此推测miRNAs可能参与了c-jun的调控。我们确定了c-Jun mRNA编码区miR-125b和miR-527的种子序列，这暗示了miRNA依赖的调控在蛋白质水平上的直接参与。我们发现，与黑素细胞相比，miR-125b在恶性黑色素瘤细胞系和组织样本中的表达显著降低，而miR-527的表达没有变化。在进一步的功能实验中，用前miR-125b处理黑色素瘤细胞可以强烈地抑制细胞的增殖和迁移，支持miR-125b在黑色素瘤中的作用。另外，前miR-125b基因在黑色素瘤细胞中表达下调，但不影响c-jun蛋白的表达。利用荧光素酶编码区含有miR-125b种子序列的报告质粒进行荧光素酶检测，证实了与miR-125b的直接相互作用。AgO-2免疫沉淀结果显示，在黑色素瘤细胞中，前miR-125b基因转染后，c-jun基因在RNA诱导的沉默复合体中积聚。综上所述，我们确定了miR-125b在恶性黑色素瘤中的重要作用。此外，我们还证实了该miRNA对c-jun的转录后调控作用，表明c-jun是miR-125b对黑色素瘤细胞作用的主要介导物。
A fundamental event in the development and progression of malignant melanoma is the deregulation of cancer-relevant transcription factors. We recently showed that c-Jun is a main regulator of tumor progression in melanoma and thus the most important member of the AP-1 transcription factor family for this disease. Interestingly, we revealed that c-Jun expression was regulated on the post-transcriptional level and therefore speculated that miRNAs could be involved in c-Jun regulation. We determined seed sequences for miR-125b and miR-527 in the coding region of c-Jun mRNA that hints at the direct involvement of miRNA-dependent regulation on the protein level. We found that the expression of miR-125b was significantly reduced in malignant melanoma cell lines and tissue samples compared with melanocytes, whereas miR-527 remained unchanged. In further functional experiments, treatment of melanoma cells with pre-miR-125b resulted in strong suppression of cellular proliferation and migration, supporting the role of miR-125b in melanoma. In addition, transfection of pre-miR-125b led to strong downregulation of c-Jun protein but not mRNA expression in melanoma cells. Luciferase assays using reporter plasmids containing the miR-125b seed sequence in the luciferase coding region confirmed the direct interaction with miR-125b. Furthermore, immunoprecipitation of Ago-2 revealed that c-Jun mRNA accumulated in the RNA-induced silencing complex after pre-miR-125b transfection in melanoma cells. In summary, we identified an important role for miR-125b in malignant melanoma. Moreover, we demonstrated post-transcriptional regulation of c-Jun by this miRNA and showed that c-Jun is a main mediator of the effects of miR-125b on melanoma cells.