(E)-2,4-bis(p-hydroxyphenyl)-2-butenal has an antiproliferative effect on NSCLC cells induced by p38 MAPK-mediated suppression of NF-κB and up-regulation of TNFRSF10B (DR5).

BACKGROUND AND
PURPOSE: The Maillard Reaction Products (MRPs) are known to be effective in chemoprevention. Here we focused on the anticancer effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal (a MRP) on human non-small-cell lung cancer (NSCLC) cells and its mechanism of action. EXPERIMENTAL APPROACH: We analysed the activity of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal on NSCLC cells (NCI-H460 and A549) by use of Western blot analysis for major apoptotic proteins, MAPK, NF-κB and death receptor expression. We also used RT-PCR to determine its effects on death receptor mRNA expression, EMSA for effects on NF-κB DNA binding activity and colony formation assay for effects of inhibitors on (E)-2,4-bis(p-hydroxyphenyl)-2-butenal's actions. KEY
RESULTS: (E)-2,4-bis(p-hydroxyphenyl)-2-butenal induced a concentration (10-40 μg·mL⁻¹)- and time (30 min-72 h)-dependent inhibitory effect on the growth of NSCLC cells due to induction of apoptosis. Concomitantly, it significantly increased the expression of apoptotic proteins such as cleaved caspase-3, cleaved caspase-9, Bax and p53, but down-regulated the expression of anti-apoptotic proteins Bcl-2, cIAP1 and cIAP2. This effect was induced by up-regulation of MAPK and death receptor proteins TNFRSF12, TNFRSF10B and TNFRSF21, but suppression of NF-κB. Of the death receptors activated, only TNFRSF10B knock down with siRNA reversed the effect of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal. Even though all the MAPKs were activated, only pretreatment with a p38 MAPK inhibitor reversed (E)-2,4-bis(p-hydroxyphenyl)-2-butenal-induced cell growth inhibition, increase in cleaved caspase-3, -9 and TNFRSF10B expression, and NF-κB inactivation. CONCLUSIONS AND IMPLICATIONS: (E)-2,4-bis(p-hydroxyphenyl)-2-butenal induces apoptosis in NSCLC cells by p38 MAPK-mediated suppression of NF-κB and activation of TNFRSF10B, which then activates the caspase-3 and caspase-9 pathways.