Inhibitory Effect Of Lidamycin On Angiogenesis Of Zebrafish Embryos And Its Mechanism

Angiogenesis is the inevitable path to the tumor growth, and therefore anti-angiogenesis becomes a promising anticancer strategy and has curative effect to different kinds of tumors. Therefore, finding an effective tumor angiogenesis inhibitors has drawn much attention in the pharmaceutical community. Lidmycin (LDM), which is produced by actinomycetes, is an extremely potential anticancer antibiotic. Previous studies shown that LDM have could inhibit the proliferation and migration of endothelial and tumor cells. To study the in vivo anti-angiogenesis of LDM and the related mechanisms, zebrafish model was employed, which is a convenient, accurate and widely used animal model. In our present study, the inhibition of LDM on angiogenesis in zebrafish embryos was investigated. Furthermore, the molecular mechanisms underlying the anti-angiogenesis were illustrated.After treatment with different concentration of LDM, angiogenesis defects of zebrafish embryos were observed using a light microscope, including pericardial edema and reduced numbers of circulating red blood cells. Quantitative endogenous alkaline phosphatase (EAP) assay showed that LDM could significantly suppress the vessel growth of zebrafish embryos. The vessel growth is 74.3% and 62.9 % at the dose of 1μmol/L and 2.5μmol/L compared with control group. Alkaline phosphatase staining and transgenic zebrafish assay indicated that LDM could cause vascular defects of zebrafish embryos in a dose-dependent manner. A higher dose of LDM resulted in a more marked inhibition of subintestinal vessels (SIVs). Tumor angiogenesis is regulated by a variety of inhibiting and activating factors, and VEGF (vascular endothelial growth factor) is one of the most important activators. In the following experiments, the roles of VEGF in the LDM induced anti- angiogenesis on zebrafish embryos were studied using RT-PCR assay, quantitative reverse transcriptase real-time PCR (qRT-PCR) and western blotting analysis. The results revealed that LDM could significantly inhibit the expression of VEGF protein, while the expression of mRNA was not affected obviously. The present study suggests that LDM inhibits the zebrafish embryo angiogenesis by down-regulation of VEGF expression.