Overexpression of miRNA-497 inhibits tumor angiogenesis by targeting VEGFR2

Objectives Recent studies reported that miR-497 exhibited inhibitory effects in a variety of cancers. However, whether miR-497 is involved in inhibiting angiogenesis, which is critical for tumor growth and metastasis, is still unknown. Hence, the purpose of this study was to investigate the potential role of miR-497 in tumor angiogenesis in breast cancer.

Methods Proliferation and apoptosis analyses were conducted to explore the potential function of miR-497 in human umbilical vein endothelial cells (HUVECs) by using MTT and TUNEL assays. Western blotting (WB) analysis was employed to validate the downstream targets of miR-497 that influence endothelial cells survival and proliferation. Furthermore, in order to disclose the relationship between miR-497 and tumor angiogenesis, VEGFR2-luc transgenic mice were treated with miR-497 mimic and applied to monitor angiogenesis and tumor growth in vivo by using bioluminescent imaging (BLI). Finally, cancer tissues of miR-497 mimic treatment and control groups were employed to analyze the correlation between miR-497 levels and tumor angiogenesis through WB and immunohistochemistry analysis.

Results Overexpression of miR-497 demonstrated inhibitory effects on VEGFR2 activation and downstream Raf/MEK/ERK signal transduction pathways in both HUVECs and tumor tissues. Moreover, overexpression of miR-497 effectively induced endothelial cells apoptosis by targeting VEGFR2 and downstream PI3K/AKT signaling pathway. Furthermore, miR-497 exhibited anti-angiogenesis and anti-tumor effects in the VEGFR2-luc breast tumor model proven by in vivo BLI, in vitro WB and immunohistochemistry analysis.

Conclusions miR-497 inhibits tumor angiogenesis and tumor growth via targeting VEGFR2 in vitro and in vivo, indicating miR-497 can be explored as a potential drug candidate for cancer therapy.

Research Support This work was supported, in part, by the National Natural Science Foundation of China (31210103913), National Natural Science Foundation of China (81130028), Key Grant Project of Heilongjiang Province (GA12C302), and the Office of Science (BER), U.S. Department of Energy (DE-SC0008397).