Department of Dermatology, Ghent University Hospital, 9000 Ghent, Belgium.
Int J Oncol. 2013 Apr;42(4):1443-51. doi: 10.3892/ijo.2013.1823. Epub 2013 Feb 12.
MicroRNAs (miRNAs) are post-transcriptional modulators of gene expression which play important roles in tumorigenesis and cancer metastasis. Since they are often highly deregulated in various types of cancer, miRNAs may be effective treatment targets. miRNA profiling studies of melanoma have led to the identification of several tumor suppressor miRNAs. One of these include miR-145, although functional data proving its specific function are limited. Therefore, in this study, we examined the expression levels of miR-145 in three melanoma cell lines (BLM, FM3P and WM793). Additional gain-of-function experiments revealed that miR-145 exerts an anti-proliferative effect in the primary, non-invasive melanoma cell line, WM793, whereas cell migration and the invasive potential of metastatic melanoma cells was suppressed following transfection with miR-145 mimics. In order to investigate the mechanisms by which miR-145 exerts its invasion suppressor function, we examined the expression level of target genes [fascin homolog 1 (FSCN1), myosin‑Va (MYO5A and SOX9] and that of an indirect target (RAB27A) following the overexpression of miR-145. The results showed that SOX9, MYO5A and RAB27A were not involved in the biological effects caused by miR-145 mimics. Surprisingly, we discovered that miR-145 in melanoma, in contrast to many other tumor types, does not necessarily act via the target, FSCN1, since the downregulation of FSCN1 did not inhibit cell proliferation or migration but, on the contrary, increased cell invasion in two out of the three melanoma cell lines examined. Our in vitro data is in accordance with previously reported in vivo data describing the low expression of FSCN1 in malignant melanomas when compared to dysplastic nevi, suggesting that the expression of FSCN1 decreases as the formation and progression stage of melanoma advances. In conclusion, our data provide evidence that miR-145 is an invasion suppressor in metastatic melanoma cells. Despite the fact that it remains unclear which genes or pathways are regulated by miR-145 in melanoma, miR-145 may serve as a useful therapeutic agent in melanoma when re-expressed in situ.
微小 RNA（miRNAs）是基因表达的转录后调控因子，在肿瘤发生和癌症转移中发挥重要作用。由于它们在各种类型的癌症中经常高度失调，因此 miRNAs 可能是有效的治疗靶点。黑色素瘤的 miRNA 谱分析研究导致了几种肿瘤抑制 miRNA 的鉴定。其中包括 miR-145，尽管证明其特定功能的功能数据有限。因此，在这项研究中，我们检查了三种黑色素瘤细胞系（BLM、FM3P 和 WM793）中 miR-145 的表达水平。额外的功能获得实验表明，miR-145 在原发性、非侵袭性黑色素瘤细胞系 WM793 中发挥抗增殖作用，而转染 miR-145 模拟物后，转移性黑色素瘤细胞的迁移和侵袭潜力受到抑制。为了研究 miR-145 发挥其侵袭抑制功能的机制，我们检查了靶基因 [ fascin 同源物 1（FSCN1）、肌球蛋白 Va（MYO5A 和 SOX9]和间接靶基因（RAB27A）的表达水平，在过表达 miR-145 后。结果表明，SOX9、MYO5A 和 RAB27A 不参与 miR-145 模拟物引起的生物学效应。令人惊讶的是，我们发现黑色素瘤中的 miR-145 与许多其他肿瘤类型不同，不一定通过靶基因 FSCN1 发挥作用，因为 FSCN1 的下调不仅没有抑制细胞增殖或迁移，反而增加了在三种黑色素瘤细胞系中检查的两种细胞的侵袭。我们的体外数据与先前报道的体内数据一致，描述了与发育不良痣相比，恶性黑色素瘤中 FSCN1 的低表达，表明随着黑色素瘤形成和进展阶段的进展，FSCN1 的表达减少。总之，我们的数据提供了证据，表明 miR-145 是转移性黑色素瘤细胞的侵袭抑制剂。尽管目前尚不清楚 miR-145 在黑色素瘤中调节哪些基因或途径，但当在原位重新表达时，miR-145 可能成为黑色素瘤的有用治疗剂。
