ABSTRACT
AIM: To study the role and mechanism of curcumol in neovascularization induced by vascular endothelial growth factor(VEGF).METHODS: Human umbilical vein endothelial cells were cultured in vitro and treated with 50ng/mL VEGF and curcumol at different concentrations. Cell proliferation was detected by CCK-8 and EdU assay, the migration ability of cells was analyzed by Transwell assay, the angiogenesis ability of endothelial cells was analyzed by tube formation assay, and the change of Akt/mTORC1 signal pathway was detected by Western blot.RESULTS: CCK-8 results showed that the OD450 value of cells in 400 and 800 μmol/L curcumol+VEGF group was significantly lower than that in VEGF group(all P<0.01). EdU results showed that the rate of cell proliferation in 400 μmol/L curcumol+VEGF group was significantly lower than that in VEGF group(P<0.001). Transwell assay and the formation assay results showed that the number of migratory cells in 400 μmol/L curcumol+VEGF group was decreased, and the number and length of tube branches were also reduced compared with VEGF group(all P<0.001). Western blot results showed that curcumol significantly inhibited the expression of p-Akt and p-S6, which were downstream targets of Akt/mTORC1 pathway in cells.CONCLUSION: Curcumol can inhibit VEGF-induced cell proliferation, migration and tube formation of vein endothelial cells, and has a strong inhibitory effect on angiogenesis, which can be further studied in the treatment of ocular fundus neovascularization.
ABSTRACT
Autophagy, an evolutionarily conserved process by which components of the cell are degraded in lysosomes, may facilitate survival of cancer cells under stress conditions. 8-Azaguanine (8-AG), an inhibitor of purine nucleotide biosynthesis, shows antineoplastic activity in multiple tumor cells. However, chemoresistance has restricted its development as an anticancer agent, and the mechanism of 8-AG resistance is not fully understood. We report here that 8-AG induces a protective autophagy to eliminate its cytotoxicity, and inhibition of autophagy increases cellular sensitivity of cancer cells to 8-AG treatment. Using HepG2 or SMMC-7721 hepatic cancer cell lines, we found that 8-AG inhibited cell viability and induced intrinsic apoptosis, accompanied by the up-regulation of the pro-apoptotic protein BimS, one of Bim (also known as BCL-2-like protein 11, BCL2L11) isoforms. Furthermore, 8-AG treatment enhanced the autophagy flux by promoting the dephosphorylation and activation of Unc-51-like autophagy activating kinase 1 (ULK1) via Akt/mTORC1 (mammalian target of rapamycin complex 1) signaling inhibition. Depletion of autophagy-related gene 7 (ATG7) markedly enhanced the level of BimS, and promoted cell death in response to 8-AG. 8-AG in combination with autophagy inhibitor chloroquine (CQ) or bafilomycin A1 (Baf A1) promoted the 8-AG-induced apoptosis in hepatic cancer cells. Altogether, these findings suggest that autophagy promotes chemoresistance of cancer cells for 8-AG, and blocking autophagy increases cellular sensitivity of cancer cells to 8-AG treatment.