Figure 4.

Colicin N suppresses integrin mediated-survival pathways. (a) Western blot analysis revealed the alteration of regulatory proteins related to extrinsic apoptosis including caspase-8 and c-FLIP. (b) The increase of cleaved caspase-8 accompanied by down-regulation of caspase-8 and c-FLIP was observed after culture lung cancer H460 cells with colicin N at 5–15 µM for 12 h. (c) Colicin N mediated mitochondrial apoptosis signal through up-regulation of pro-apoptosis protein, Bax and decreased anti-apoptosis Mcl-1 protein. (d) Meanwhile, there was no significant alteration of Bcl-2 level in colicin N-treated H460 cells. (e) Down-regulation of integrin β1 and αV were demonstrated in lung cancer H460 cells cultured with 15 µM of colicin N for 12 h. Interestingly, the reduction of integrin β1 was also noted in the cells treated with 5-10 µM colicin N. (f) Treatment with colicin N (5–15 µM) obviously suppressed p-Akt level while Erk and its activated form (p-Erk) was fairly altered in H460 cells. Values are means of the independent triplicate experiments ± SD. * p ≤ 0.05 versus non-treated control.