| Pancreatic cancer is the forth and sixth leading cause of cancer deaths in the United States and Hong Kong, respectively. The morbidity of pancreatic cancer is almost equal to its mortality rate. Poor diagnosis and intrinsic resistance to chemotherapy are the major characteristics for pancreatic cancer. Therefore, new therapeutic strategy is urgently warranted to overcome the drug-resistance challenge in the management of pancreatic cancer.;Nine Chinese medicinal herbs were selected for the screening experiment and, among them, BJ exhibited the most potent cytotoxic action on the three pancreatic adenocarcinoma cell lines, namely PANC-1, SW-1990 and CAPAN-1, with IC50 values of 2.5mug/ml, 5.1mug/ml and 1.5mug/ml, respectively. BD, one of the main chemical compounds found in BJ was found to possess strong apoptogenic effect in PANC-1 cells, as evidenced by DNA condensation and fragmentation, sub-G1 phase formation, proteolytic activation of caspase 3, 8 and 9, and attenuation of bcl-2 activity. Further mechanistic studies revealed that the apoptotic signals generated by BD were transduced from the cell membrane to nucleus via the mediation of p38-MAPK signaling pathway while the reactive oxygen species (ROS) was found to accumulate in BD-treated PANC-1 cells. The activation p38-MAPK phosphorylation was inhibited by pretreatment with an antioxidant. However, the inhibition of NF-kappaB activity and downregulation of anitapoptotic genes in BD-treated cells was independent of the ROS changes.;In vivo study demonstrated that daily administration of BD through intravenous injection for ten days in nude mice bearing pancreatic cancer cells effectively reduced tumor growth in terms of tumor weight and size, while showing no significant toxicity in heart, liver and kidney tissues of the mice.;In conclusion, the present study successfully demonstrate BJ as a potent anti-pancreatic cancer herb; BD is the main ingredient for its cytotoxic and apoptotic effects on the pancreatic cancer cells through activation of the redox-sensitive p38-MAPK signaling pathway and reduction of anti-apoptotic activity by inhibition of NF-kappaB activation in pancreatic cancer cells. The in vivo efficacy and low toxicity of BD render this chemical compound to be a potential for its further development into an anti-pancreatic cancer agent.;In recent decades, the application of Chinese herbal medicine has become an increasingly popular approach and alternative to treating cancer. Moreover, Chinese herbal medicine is the source for the discovery of novel anti-cancer drugs. For example, irinotecan and topotecan, the analogues of camptothecin which is isolated from the bark and stem of Camptotheca acuminate are found to be effective in ovarian, lung and colon cancers. Given that Chinese medicine is commonly used in the treatment of cancers, we postulate that Chinese herbs are a valuable source to possess anti-pancreatic cancer compounds. Accordingly, the aims of the present project are: (1) to screen Chinese medicinal herbs which has the most potent cytotoxic activity in pancreatic cancer cells in vitro; (2) to isolate and identify the effective compound in Brucea javanica (BJ) which mediates apoptosis in pancreatic cancer cell lines; (3) to study the mechanistic pathways involved in brucein D - (BD, a quassinoid found in abundance in BJ) mediated apoptosis in pancreatic cancer in vitro; and (4) to evaluate the efficacy of BD in pancreatic cancer using an xenograft animal model of pancreatic cancer. |
