Antitumor activity of a novel bis-aziridinylnaphthoquinone (AZ4) mediating cell cycle arrest and apoptosis in non-small cell lung cancer cell line NCI-H460

Aim: The cytotoxic activities of a series of bis-aziridinylnaphthoquinone, AZ1 to AZ4, on human lung carcinoma cell lines, H460, and normal lung cells fibroblast cell line, MRC-5, and the mechanisms of H460 cells induced by AZ4 were investigated. Methods: The MTT assay was used to determine the cell proliferation. Cell cycle was analysed by FACS. The activity of caspase 3, 8 and 9 was determined by cell-permeable fluorogenic detection system. Western blot assay was used to evaluate the regulation of cyclin B, Cdc-2, p53, p21, and the Bcl-2 protein. Results: AZ1 to AZ4 displayed various cytotoxicity activities against H460 and MRC-5 cells. Compared to those compounds, AZ4 was with the most effective agent among the 5 tested analogues at reducing H460 cell viability with an IC₅₀ value of 1.23 μmol/L; it also exhibited weak cytotoxicity against MRC-5 cells with an IC₅₀ value of 12.7 μmol/L. The results show that growth arrest on the G₂-M phase of H460 cells induced by AZ4 for 24 h was discovered, and this might be altered with the reduced Cdc-2 protein expression of 47% at 2.0 μmol/L AZ4, but not with cyclin B protein expression. The AZ4 treated cells were then led to apoptosis after 48 h. This was associated with the activation of apoptotic enzyme caspase 3 and mediated by caspase 8, but not caspase 9 at various concentrations of AZ4 after being cultured for 48 h and 30 h, respectively. The anti-apoptotic protein (Bcl-2) expression in H460 cells altered by 39% with downregulation, and the p53 protein by 25% with upregulation after being cultured with 2.0 μmol/L AZ4 for 48 h. In a time-dependent wanrer, the expression of the p53 and p21 proteins were increased to the maximum at 24 h, and then decreased at 48. Conclusion: AZ4 represents a novel antitumor aziridinylnaphthoquinone with therapeutic potential against the non-small cell lung cancer cells.