The SMAC mimetic AT-101 exhibits anti-tumor and anti-metastasis activity in lung adenocarcinoma cells by the IAPs/caspase-dependent apoptosis and p65-NFκB cross-talk

Objective(s): The Inhibitors of Apoptosis (IAPs) regulate initiator and effector phases of caspase mediated apoptosis. This study evaluates the effects of SMAC mimetic AT-101 in regulation of IAPs/caspases/NF kappa B-p65 in an adenocarcinoma cell line. Materials and Methods: MTT assay was performed in the NCI-H522 cell line. Flow cytometry was used for detecting cell cycle, apoptosis, and NF kappa B-p65 regulation. Effects of AT-101 on IAPs and caspases were determined by quantitative real time-PCR and western blotting. AutoDock-VINA was used for computational analysis. Results: AT-101 reduced the cell proliferation of NCI-H522 with a GI50 value of 7 mu M. The compound arrested adenocarcinoma cells in the G1 phase of the cell cycle and increased early and late phase apoptosis while decreasing tumor-cell trans-migration. AT-101 treatment to NCI H522 at a concentration of 0.35 mu M decreased XIAP, cIAP-1, and cIAP-2 mRNA levels to 4.39 +/- 0.66, 1.93 +/- 0.26, and 2.20 +/- 0.24 folds, respectively. Increased dose of AT-101 at 0.7 mu M concentration further decreased XIAP, cIAP-1, and cIAP-2 mRNA levels to 2.44 +/- 0.67, 1.46 +/- 0.93, and 0.97 +/- 0.10 folds, respectively. Similar effects of a dose-dependent decrease in the protein expressions of XIAP, cIAP-1, and cIAP-2 were observed with AT-101 treatments, while a dose-responsive increase in the mRNA and protein expression levels of caspase 6 and caspase 7 was observed in the NCI-H522 cell line. The compound exhibited binding affinity (-6.1 kcal/mol) and inhibited NF kappa B-p65 in these cells. Conclusion: AT-101 had anti-tumor efficacy against lung adenocarcinoma cells which could be mediated through IAPs/caspase-dependent apoptosis and NF kappa B-p65 cross talk. Results from this study suggests a signal cross talk between IAPs and NFkB and open new channels for further investigations in therapeutic intervention against lung cancer management.