Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, People's Republic of China.
Hepatology. 2013 Aug;58(2):642-53. doi: 10.1002/hep.26373.
Hepatocellular carcinoma (HCC) is characterized by active angiogenesis and metastasis, which account for rapid recurrence and poor survival. There is frequent down-regulation of miR-195 expression in HCC tissues. In this study, the role of miR-195 in HCC angiogenesis and metastasis was investigated with in vitro capillary tube formation and transwell assays, in vivo orthotopic xenograft mouse models, and human HCC specimens. Reduction of miR-195 in HCC tissues was significantly associated with increased angiogenesis, metastasis, and worse recurrence-free survival. Both gain-of-function and loss-of-function studies of in vitro models revealed that miR-195 not only suppressed the ability of HCC cells to promote the migration and capillary tube formation of endothelial cells but also directly repressed the abilities of HCC cells to migrate and invade extracellular matrix gel. Based on mouse models, we found that the induced expression of miR-195 dramatically reduced microvessel densities in xenograft tumors and repressed both intrahepatic and pulmonary metastasis. Subsequent investigations disclosed that miR-195 directly inhibited the expression of the proangiogenic factor vascular endothelial growth factor (VEGF) and the prometastatic factors VAV2 and CDC42. Knockdown of these target molecules of miR-195 phenocopied the effects of miR-195 restoration, whereas overexpression of these targets antagonized the function of miR-195. Furthermore, we revealed that miR-195 down-regulation resulted in enhanced VEGF levels in the tumor microenvironment, which subsequently activated VEGF receptor 2 signaling in endothelial cells and thereby promoted angiogenesis. Additionally, miR-195 down-regulation led to increases in VAV2 and CDC42 expression, which stimulated VAV2/Rac1/CDC42 signaling and lamellipodia formation and thereby facilitated the metastasis of HCC cells.
miR-195 deregulation contributes to angiogenesis and metastasis in HCC. The restoration of miR-195 expression may be a promising strategy for HCC therapy.
肝细胞癌（HCC）的特征是活跃的血管生成和转移，这导致了快速复发和较差的生存。在 HCC 组织中经常下调 miR-195 的表达。在这项研究中，通过体外毛细血管形成和 Transwell 测定、体内原位异种移植小鼠模型和人 HCC 标本研究了 miR-195 在 HCC 血管生成和转移中的作用。HCC 组织中 miR-195 的减少与增加的血管生成、转移和更差的无复发生存率显著相关。体外模型的功能获得和功能丧失研究表明，miR-195 不仅抑制了 HCC 细胞促进内皮细胞迁移和毛细血管形成的能力，而且直接抑制了 HCC 细胞迁移和侵袭细胞外基质凝胶的能力。基于小鼠模型，我们发现诱导表达 miR-195 可显著降低异种移植肿瘤中的微血管密度，并抑制肝内和肺转移。随后的研究揭示，miR-195 直接抑制了促血管生成因子血管内皮生长因子（VEGF）和促转移因子 VAV2 和 CDC42 的表达。miR-195 靶分子的敲低模拟了 miR-195 恢复的效果，而这些靶分子的过表达则拮抗了 miR-195 的功能。此外，我们揭示了 miR-195 的下调导致肿瘤微环境中 VEGF 水平升高，随后激活内皮细胞中的 VEGF 受体 2 信号，从而促进血管生成。此外，miR-195 的下调导致 VAV2 和 CDC42 表达增加，从而刺激 VAV2/Rac1/CDC42 信号和片状伪足形成，从而促进 HCC 细胞的转移。
miR-195 的失调导致 HCC 的血管生成和转移。恢复 miR-195 的表达可能是 HCC 治疗的一种有前途的策略。
