MiR-5586-5p Suppresses Hypoxia-induced Angiogenesis Through Multiple Targeting of HIF-1α, HBEGF and ADAM17 in Breast Cancer.

Abstract

Background/aim: Hypoxia-inducible factor-1 alpha (HIF-1α) plays a key role in the cellular response to hypoxia, which plays a crucial role in the induction of abnormal angiogenesis and metastasis. Understanding the mechanism for the regulation of angiogenesis by HIF-1α-regulating miRNA will contribute to developing the strategy to prevent metastasis.

Materials and methods: We conducted a functional screening for HIF-1α-inhibiting miRNAs by evaluating the effects of miRNA mimics on HIF-1α expression and identified miR-5586-5p as an angiogenesis inhibitor through a mechanistic study. Angiogenic activity was assessed by tube formation assays using HUVEC cells exposed to conditioned media from miRNA-transfected breast cancer cells. In vivo activity of miR-5586-5p was examined through intratumoral injection of miRNA in orthotopic xenograft mice established by injecting MDA-MB-231 cells into the mammary fat pads of BALB/c nu/nu mice.

Results: The expression of the critical proangiogenic factors vascular endothelial growth factor A (VEGFA) and angiopoietin-like protein 4 (ANGPTL4) was inhibited by miR-5586-5p. Migration and tube formation of human umbilical vein endothelial cells were reduced in the conditioned medium prepared from miR-5586-5p-transfected cells. miR-5586-5p also suppressed the expression of heparin-binding EGF-like growth factor (HBEGF) and a disintegrin and metalloprotease 17 (ADAM17), which play a role in hypoxic signaling to induce the expression of VEGFA and ANGPTL4. HIF-1α, HBEGF, and ADAM17 were verified as the direct targets of miR-5586-5p responsible for the angiogenesis-suppressing function of miR-5586-5p. Expression levels of miR-5586-5p were lower in tumor tissues than in neighboring normal tissues of breast cancer patients. The expression of miR-5586-5p was inversely correlated to those of HIF-1α, HBEGF, ADAM17, VEGFA, and ANGPTL4. Angiogenesis and subsequent tumor growth were suppressed by intratumoral injection of miR-5586-5p in orthotopic MDA-MB-231 xenografts in mice.

Conclusion: A potent tumor-suppressive function of miR-5586-5p applicable for the development of a novel cancer treatment strategy is herein described.