A cytokine known as tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has the ability to precisely cause the death of cancer cells, while normal cells are left undisturbed. Recent studies show that certain cancer cells are sensitive to the apoptotic effect of TRAIL. In this study, HT29 colorectal adenocarcinoma cells exposed to TRAIL were treated with heptaphylline and 7-methoxyheptaphylline from Clausena harmandiana in an effort to comprehend the mechanisms involved behind this activity. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test was utilized to determine cell survival, and phase contrast microscopy was used to examine cell morphology. Through using real-time RT-PCR, Western blotting, and RT-PCR, the molecular mechanisms were investigated. According to the findings, whilst hepataphylline caused cytotoxicity in normal colon FHC cells, in comparison to healthy colon FHC cells, 7-methoxyheptaphylline inhibited cancer cells in a concentration-dependent manner. Heptaphylline alone or in conjunction with TRAIL showed no discernible effect on TRAIL-induced HT29 cell death, but 7-methoxyheptaphylline boosted caspase-3 cleavage. The study showed that the c-Jun N-terminal kinase (JNK) pathway was responsible for the 7-methoxyheptaphylline's enhancement of the death receptor 5 (DR5) mRNA, TRAIL receptor, and protein. The results demonstrated that the 7-methoxyheptaphylline of Clausena harmandiana increased the expression of DR5 via the JNK pathway, intensifying TRAIL-induced HT29 cell death.
Keywords: 7-methoxyheptaphylline; Clausena harmandiana; apoptosis; cancer; death receptor-5; heptaphylline.