MicroRNA-195 Suppresses Angiogenesis and Metastasis of Hepatocellular Carcinoma by Inhibiting the Expression of VEGF, VAV2, and CDC42

Abstract

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. Conclusion: miR-195 deregulation contributes to angiogenesis and metastasis in HCC. The restoration of miR-195 expression may be a promising strategy for HCC therapy. (HEPATOLOGY 2013;58:642-653) G lobally, hepatocellular carcinoma (HCC) is a common and highly lethal malignancy. Active angiogenesis and frequent metastasis are responsible for rapid recurrence and poor survival of HCC. Therefore, identifying molecules that can suppress angiogenesis and metastasis may provide novel targets for HCC therapies.MicroRNAs (miRNAs) constitute a class of endogenous small noncoding RNAs that suppress protein expression by base-pairing with the 3 0 -untranslated

microRNA-195 functions as a tumor suppressor by inhibiting CBX4 in hepatocellular carcinoma

“…Interestingly, miR-195 is frequently downregulated and plays different roles in multiple cancer types (12)(13)(14)(15)(16). A recent study found that miR-195 is associated with tumor metastasis and angiogenesis in HCC cells (17). As yet, the exact mechanisms of miR-195 in HCC development still remain largely unknown.…”

MicroRNA-195 targets VEGFR2 and has a tumor suppressive role in ACHN cells via PI3K/Akt and Raf/MEK/ERK signaling pathways

“…Recently, it has been shown that some microRNAs inhibit cancer via suppressing certain cytokines. For example, hepatocellular carcinoma was inhibited by miR-195 through VEGF inhibition and colorectal cancer was inhibited by miR-497 via regulating IGF1 (32,33). Slaby et al (9) showed that miR-195 was decreased in tumors from patients who developed relapse and in primary metastasis.…”

The regulatory role of microRNAs in angiogenesis‐related diseases

“…MiR‐195 enhances the remodelling of angiocarpy by improving the Ang 2 and TGF‐β1/Smads signalling pathways 136. Moreover, down‐regulation of miR‐195 increases VEGF in the tumour microenvironment, which subsequently activates VEGFR2 signalling in ECs and thereby enhances angiogenesis 135. Thus, miR‐195 plays an important role in the physiological and pathological processes of angiogenesis and it is likely to be a prospective therapeutic target for repressing angiogenesis.…”