Autophagy promotes the survival and development of tumors by participating in the formation of vasculogenic mimicry

Abstract

Autophagy, type II nonapoptotic cell death, is characterized by the formation of double-membrane cytosolic vesicles, the recycling of damaged cytoplasmic content and the maintenance of genetic stability and cellular homeostasis, under conditions of nutrient starvation, hypoxia or other therapeutic stress. In the present study, we comprehensively discuss its indispensable role in the formation of vasculogenic mimicry (VM), capillary-like tubes consisting of cells from the tumor itself instead of vascular endothelial cells. A short hairpin RNA (shRNA) to silence beclin1, an autophagy-specific gene, was designed, synthesized and subcloned into a vector to establish an autophagy-inhibited group, while negative control and blank groups were also established using human gastric cancer SGC7901 cells. We then investigated the VM formation ability of these three groups and detected changes in gene expression, survival and invasion correspondingly. The results showed that, following the formation of VM, the expression of pluripotent genes (c-myc, oct3/4, sox-2) and autophagy-specific genes (beclin1, ATG5, ATG7) were increased, which was consistent with the negative control cell group. However, the autophagy inhibited cell group did not form VM, and the expression of pluripotent genes was decreased. Moreover, the inhibition of autophagy reduced the survival and invasive ability of cancer cells under stress. We suggest that during the formation of VM, the stable expression of genes and the maintenance of survival and invasion are indispensable. Under a stress environment, autophagy is activated to maintain the stability of gene expression, maintain survival and invasive ability and facilitate VM formation, which can provide nutrients, oxygen and invasive channels to tumors, facilitating survival and development under stress.