Department of Laboratory Medicine, Keenan Research Centre in the Li Ka Shing Knowledge Institute St. Michael's Hospital, Toronto, Ontario, Canada.
Am J Pathol. 2012 Apr;180(4):1675-87. doi: 10.1016/j.ajpath.2011.12.030. Epub 2012 Feb 9.
The von Hippel-Lindau (VHL) gene is lost in ≈ 70% of all renal cell carcinomas (RCCs); however, increasing evidence supports the involvement of alternative mechanisms in the regulation of VHL expression, including suppression by microRNAs (miRNAs). miRNAs are small, noncoding RNA molecules that regulate gene expression through binding to target mRNAs. In this study, we found that miRNAs, which are dysregulated in cases of RCC, can target multiple members of RCC-related signaling pathways. Importantly, both VHL and the hypoxia-inducible factor 1-α gene are experimentally validated and are likely direct targets of miR-17-5p and miR-224, as shown by both luciferase assay and Western blot analysis. We found a negative correlation between miR-17-5p and its two predicted targets, VEGF-A and EGLN3, and between miR-224 and its targets SMAD4 and SMAD5 in RCC specimens, suggesting that downstream signaling pathways are also modulated by clear cell RCC-dysregulated miRs. Results from our bioinformatics analysis show that a single miRNA molecule can target multiple components of the same pathway and that multiple miRNAs can target the same molecule. Our results also indicate that miRNAs represent a mechanism for the inactivation of VHL in cases of RCC and can elucidate a new dimension in cancer pathogenesis. As such, miRNAs exemplify new potential therapeutic targets with a significant effect on both tumor growth and metastatic potential.
希佩尔-林道（von Hippel-Lindau，VHL）基因在 ≈70%的肾细胞癌（renal cell carcinomas，RCC）中丢失；然而，越来越多的证据支持替代机制在 VHL 表达调控中的作用，包括 microRNAs（miRNAs）的抑制作用。miRNAs 是小的非编码 RNA 分子，通过与靶 mRNA 结合来调节基因表达。在这项研究中，我们发现 RCC 病例中失调的 miRNAs 可以靶向多个 RCC 相关信号通路的成员。重要的是，VHL 和缺氧诱导因子 1-α基因都是实验验证的，并且很可能是 miR-17-5p 和 miR-224 的直接靶标，这通过荧光素酶测定和 Western blot 分析都得到了证实。我们在 RCC 标本中发现 miR-17-5p 与其两个预测靶标 VEGF-A 和 EGLN3 之间以及 miR-224 与其靶标 SMAD4 和 SMAD5 之间存在负相关，表明下游信号通路也受到 clear cell RCC 失调的 miRs 的调节。我们的生物信息学分析结果表明，单个 miRNA 分子可以靶向同一途径的多个成分，并且多个 miRNAs 可以靶向同一分子。我们的结果还表明，miRNAs 代表了 RCC 中 VHL 失活的一种机制，并可以阐明癌症发病机制的新维度。因此，miRNAs 是新的潜在治疗靶点的范例，对肿瘤生长和转移潜能都有显著影响。
