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The relationship between the role of VEGF and autophagy in the process of retinal angiogenesis is still unclear. In this study, we explored this issue by using the mouse retinal vascular endothelial cell (RVEC) as a model.
RVECs were divided into the following groups: control, hypoxia (H), 3-methyladenine (3-MA) + H, VEGF + H, 3-MA + VEGF+H, anti-VEGF antibody + H, 3-MA+ anti-VEGF antibody + H. We then examined activation of autophagy by detecting formation of autophagosomes with transmission electron microscopy (TEM) and by counting the number of green fluorescent protein-positive (GFP+) puncta in RVECs. The turnover of microtubule associated protein 1 light chain 3 B (LC3B) and VEGF were examined by western blot. Cell migratory capacity was measured with wound healing assay and transwell assay. The capillary formation assay was performed to investigate the angiogenic capacity.
Hypoxia led to an increased number of autophagosome and of the GFP+ puncta, an increased ratio of LC3B-II/I and enhanced migratory and capillary-formation capacities of RVECs. Pre-treatment with 3-MA attenuated activation of autophagy and abrogated the enhanced cell migration and capillary formation under hypoxia. Exposure to VEGF significantly increased migratory and capillary formation capacities of RVECs under hypoxia and 3-MA decreased VEGF-induced angiogenesis without its expression. Formation of autophagosome, the number of GFP+ puncta of RVECs and expression of LC3B-II/I were both elevated in cells treated with anti-VEGF antibody and these effects were partially inhibited by 3-MA pretreatment.
Our present data may identify autophagic response as a novel target for enhancing the therapeutic efficacy of angiogenesis inhibitors.