ACE2 inhibits breast cancer angiogenesis in vitro. (a) Bubble plot of ACE2 and breast cancer angiogenesis obtained from the GO enrichment analysis. (b) Proliferation of HUVECs after 72 h in the TCM from transfected MDA-MB-231 and MCF-7 cells. (c) Tube formation ability of HUVECs cultivated for 6 h in the TCM from transfected MDA-MB-231 and MCF-7 cells. (d) Wound healing ability of HUVECs after 48 h in the TCM from transfected MDA-MB-231 and MCF-7 cells. Microscope magnification: 50×. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001

ACE2 inhibits breast cancer angiogenesis in vivo. (a) Equal number of Dil-labelled transfected MDA-MB-231 and MCF-7 cells were microinjected into the perivitelline space of embryos at 48 h post-fertilization. Thick arrows point to the injection sites. BF: bright field; RF: rhodamine fluorescence. (b) Dissemination and metastasis of the tumour cells in the zebrafish at 24 h post-injection (observed under a fluorescence microscope) and quantification of the number of disseminated foci and maximal metastatic distance. Small arrowheads point to the disseminated and metastatic tumour foci (MDA-MB-231, n = 9; MCF-7, n = 6). (c) Vasculature and neo-angiogenesis surrounding the primary tumour and metastasis sites in the zebrafish at 24 h post-injection (observed under a confocal microscope). Thin arrows point to newly formed tumour vessels. Fluorescence microscope magnification: 50×. Confocal microscope magnification: 200×. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001