Abstract 1261: TRAIL-induced pro- and antiapoptotic kinase activation in non-small cell lung cancer cells

Abstract Non-small cell lung cancer (NSCLC) is a disease with poor prognosis and novel therapeutic approaches are greatly needed. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) belongs to the TNF gene superfamily and it mediates its apoptotic function through interaction with the death receptors, DR4 and DR5. An important feature of TRAIL is its ability to induce apoptosis in a wide variety of tumors without harming normal cells, making it an attractive anti-cancer therapeutic compared to conventional anti-cancer agents. However, TRAIL is also able to activate signaling pathways that are implicated in cell survival and cell proliferation, counteracting its death-inducing effects. Thus, TRAIL-based therapies combined with inhibitors of pro-survival signals are expected to have beneficial therapeutic effects. In this study, we examined the pro-survival signaling induced by recombinant TRAIL in NSCLC cells. We monitored the activation of a number of kinases known to be involved in TRAIL signaling by Western blotting, including p38 MAPK, JNK, ERK and Akt. In addition we employed PepChip kinase arrays. With these arrays 1024 peptide kinase substrates can be screened in one experiment, whereby a comparison of kinase patterns between untreated and treated cells can be obtained. H460 and A549 NSCLC cell lines, which are sensitive and resistant for TRAIL, respectively, were exposed to 50 ng/ml TRAIL for different periods of time (5, 10, 15, 30, 60, 120, 180, 240 minutes) to evaluate the kinetics of the kinases. In H460 cells, TRAIL phosphorylated p38 MAPK after 2 hours and JNK1/2 after 3 hours. As the activation of these kinases can be both anti- and pro-apoptotic, kinase inhibitors were used to explore this further. In H460 cells the activation of JNK, ERK and Akt had anti-apoptotic activity. Inhibition of these kinases with SP600125, PD098059, and LY294002, respectively, showed a 2 fold increase in apoptosis when combined with TRAIL. The activation of MAPK p38 on the other hand was pro-apoptotic, since its inhibition with SB203580 resulted in a reduction of TRAIL-induced apoptosis in H460 cells. In resistant A549 cells, however, Akt, ERK, p38 MAPK, and JNK1/2 activation appeared to have anti-apoptotic activity. Furthermore, in these cells an increase in IκBα phosphorylation was observed that was not seen in H460 cells, where levels of phosphorylated IκBα decreased after 1 hour that correlated with cleavage of RIP. Thus reduction of NFκB activation could be associated with TRAIL sensitivity. Additional experiments, including the PepChip kinase arrays, are ongoing to further examine the involvement of these and other kinases in TRAIL sensitivity and for possible use in sensitization strategies. In conclusion, we observed differential TRAIL-dependent activation of p38 MAPK, JNK1/2, ERK, Akt and IκBα in sensitive and resistant NSCLC cells and the relationship with TRAIL sensitivity is currently further explored. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1261.