Involvement of NSAID‐activated gene‐1 in a novel synthetic hexahydrocannabinol analogue‐induced growth inhibition and apoptosis of colon cancer cells

Abstract

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.