A New Cyclooxygenase-2 Inhibitor, (1E,4E)-1,5-Bis(2-bromophenyl)penta-1,4-dien-3-one (GL63) Suppresses Cyclooxygenase-2 Gene Expression in Human Lung Epithelial Cancer Cells: Coupled mRNA Stabilization and Posttranscriptional Inhibition

Abstract

Lung cancer is a leading cause of morbidity and mortality worldwide. Cyclooxygenase-2 (COX-2) expression is upregulated in lung carcinomas and is considered an attractive therapeutic target. In this study, the effect of curcumin and curcumin analogues on COX-2 expression induced by phorbol 12-myristate 13-acetate (PMA) were investigated. We found that a novel curcumin analogue (GL63) inhibited PMA-induced COX-2 mRNA and protein levels in H460 cells to a greater degree than curcumin. To understand the molecular mechanisms governing COX-2 regulation, the effect on COX-2 mRNA degradation was examined; we found that GL63 significantly decreased COX-2 mRNA stability by reducing cytoplasmic localization and protein abundance of human antigen R (HuR). The 3′-untranslated region (3′-UTR) report gene assay also showed GL63 substantially reduced the 3′-UTR green fluorescent protein values, indicating that the destabilizing effect on COX-2 mRNA may be couple with the posttranscriptional inhibition of COX-2. Taken together, our results provide evidence that the novel curcumin analogue can effectively inhibit PMA-induced COX-2 expression in H460 cells, a mechanism associated with COX-2 mRNA stability and post-transcriptional regulation.