Abstract
Background: Schiff base compounds and their metal complexes have become important synthetic organic drugs due to their extensive biological activities, which include anticancer, antibacterial and antiviral effects. In this study, we investigated the cytotoxic and apoptotic effects of VALD-3, a Schiff base ligand synthesized from o-vanillin derivatives, on human breast cancer cells and the possible underlying mechanisms.Methods: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-test was used to observe the proliferation of human breast cancer MCF-7 and MDA-MB-231 cells induced on VALD-3. The effects of VALD-3 on the cell cycle were analyzed in MCF-7 and MDA-MB-231 cells by PI single staining. Hoechst 33258 staining was performed to determine if VALD-3 induced apoptosis of MCF-7 and MDA-MB-231 cells and Annexin V/PI staining was performed to quantify the percentages of apoptosis. The expression of pro-apoptotic proteins and anti-apoptotic proteins in MCF-7 and MDA-MB-231 cells was investigated by Western blotting. Wnt/β-catenin signaling pathways were also examined. The antitumor activity and survival analysis of VALD-3 in vivo was determined by the nude mice xenograft assay.Results: Flow cytometry analysis showed that VALD-3 triggered cell cycle arrest and induced apoptosis of breast cancer cells. Western blot analysis revealed that VALD-3 upregulated pro-apoptotic proteins (Bad and Bax), downregulated anti-apoptotic proteins (Bcl-2, Bcl-xl, survivin and XIAP) and increased the expression of cleaved caspase-3, cleaved caspase-8, Cyto-c and cleaved PARP. VALD-3 also regulated the Wnt/β-catenin signaling pathway in breast cancer cells, inhibiting the activation of downstream molecules. By xenografting human breast cancer cells into nude mice, we found that VALD-3 significantly suppressed tumor cell growth while showing low toxicity against major organs. In addition, survival analysis results showed that VALD-3 can significantly prolong the survival time of mice (P=0.036).Conclusion: This study is the first to show that VALD-3 induces apoptosis and cell cycle arrest in human breast cancer cells by suppressing Wnt/β-catenin signaling, indicating that it could be a potential drug for the treatment of breast cancer.
Pectenotoxin-2 induces G2/M phase cell cycle arrest in human breast cancer cells via ATM and Chk1/2-mediated phosphorylation of cdc25C
