Involvement of NSAID‐activated gene‐1 in a novel synthetic hexahydrocannabinol analogue‐induced growth inhibition and apoptosis of colon cancer cells
Nonsteroidal anti-inflammatory drug (NSAID)-activated gene-1 (NAG-1) has received greater attention as a novel molecular target for various cancers including colorectal cancer. In this study, we identified a novel synthetic hexahydrocannabinol analogue LYR-8 as a potent NAG-1 inducer which inhibited growth and induced apoptosis in a panel of human cancer cells irrespective of p53-status. In colon cancer cells, LYR-8 dramatically induced NAG-1expression in a concentration- and time-dependent manner. The induction of NAG-1 protein expression was independent of p53-activation even in wild-type HCT116 cells which had increased nuclear p53 after LYR-8 treatment. The induction of NAG-1 promoter activity by the LYR-8 was strongly associated with increased Sp1 activation as noted in various luc-promoters activities. Furthermore, pre-treatment of specific Sp1 inhibitor Mithramycin A completely reversed the LYR-8-induced NAG-1 expression. Genetically knockdown of NAG-1 using siRNA significantly reversed cell death induced by LYR-8 in both wild-type as well as mutant p53-expressing colon cancer cells, thus suggesting the role of p53-independent NAG-1 activation. These results suggest that p53-indepenent induction of NAG-1 via Sp1 activation is a promising therapeutic approach and novel compound like LYR-8 could be a potent chemotherapeutic agent targeting colon cancers irrespective of p53-mutation.