Purpose: Resistance to STI571 is an emerging problem for patients with chronic myelogenous leukemia (CML). Mutation in the kinase domain of Bcr-Abl is the predominant mechanism of the acquired resistance to STI571. In the present study, we investigated the effect of triptolide on cell survival or apoptosis in CML cells bearing Bcr-Abl-T315I or wild-type Bcr-Abl.
Experimental Design: CML cell lines (KBM5 versus KBM5-T315I, BaF3-Bcr-Abl versus BaF3-Bcr-Abl-T315I) and primary cells from CML patients with clinical resistance to STI571 were treated with triptolide, and analyzed in terms of growth, apoptosis, and signal transduction. Nude mouse xenograft model was also used to evaluate the antitumor activity.
Results: Triptolide potently down-regulated the mRNA and protein levels of Bcr-Abl independently of the caspase or proteosome activation in CML cells. It induced mitochondrial-dependent apoptosis in Bcr-Abl-T315I CML cells and primary cells from CML patients with clinical resistance to STI571. Additionally, triptolide inhibited the growth of STI571-sensitive KBM5 and STI571-resistant KBM5-T315I CML cells in nude mouse xenografts. Triptolide also down-regulated the expression of survivin, Mcl-1, and Akt in CML cells, which suggests that it may have multiple targets.
Conclusions:These findings suggest that triptolide is a promising agent to overcome STI571-resistant CML cells, and warrant a clinical trial of triptolide derivatives for CML with Bcr-Abl-T315I mutation.
NOTE Traditional Chinese medicine has used Tripterygium wilfordii Hook. f. for centuries to treat inflammation and autoimmune diseases (18–21). Among the many small molecules extracted and purified from this shrub-like vine, triptolide is the key biologically active component that mediates immunosuppression and anti-inflammation (20, 22). Of note, PG490-88, a water-soluble derivative of triptolide, has been under investigation as an immunosuppressant in a clinical trial of organ transplantation (23). Triptolide is a potent inhibitor of nuclear factor-κB– and NF-AT–mediated transcription (24). In addition, it has antitumor activities against a broad range of human cancer cells (25–28). For instance, it decreases XIAP and Mcl-1 levels and triggers apoptosis in acute myeloid leukemia cells (26). It also sensitizes tumor cells to apoptosis stimuli such as Apo2/TRAIL, tumor necrosis factor α, and various chemotherapeutic agents (29–32). Interestingly, it also down-regulates Bcr-Abl expression in K562 cells via an unknown mechanism (33).
We hypothesized that triptolide has antineoplastic activity against CML cells including STI571-resistant cells by down-regulating Bcr-Abl and, so, evaluated its translational efficacy against CML cells with wild-type or T315I-mutant Bcr-Abl. Here, we report the antineoplastic effect of triptolide against CML cell lines (including STI571-resistant lines) and primary cells from CML patients in cell culture and in mouse xenograft models. Triptolide may be a promising agent to overcome STI571- resistance caused by the Bcr-Abl-T315I mutation.
Apoptosis of human pancreatic cancer cells induced by Triptolide Guo-Xiong Zhou, Xiao-Ling Ding, Jie-Fei Huang, Hong Zhang, Sheng-Bao Wu, Jian-Ping Cheng, and Qun Wei Guo-Xiong Zhou, Xiao-Ling Ding, Jie-Fei Huang, Hong Zhang, Sheng-Bao Wu, Jian-Ping Cheng, Qun Wei, Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, ChinaAuthor contributions: Zhou GX, Ding XL contributed equally to this work; Zhou GX, Ding XL, Huang JF, Zhang H and Wu SB designed research; Ding XL, Zhang H, Wu SB, Cheng JP and Wei Q performed research; Zhou GX, Ding XL and Zhang H analyzed data; Zhou GX and Ding XL wrote the paper.
Pancreatic adenocarcinoma is characterized by a poor prognosis and lack of response to conventional therapy. The incidence has shown that no significant sign of decline throughout the past 20 years and almost equals its mortality[1–3]. The 5-year survival rate for this disease is less than 4% and the median survival time after diagnosis is less than 6 mo[2,3]. Surgical resection of the tumor is still the only effective treatment option, although only 20% of carcinomas of the head of the pancreas are resectable.Furthermore, the median survival even after apparent curative resection is only 20 mo, because of early tumor recurrence or rapid metastatic spread[2,4]. Other treatment options, such as chemotherapy or radiation therapy, provide limited palliation without significant improvement of survival in patients with unresectable pancreatic cancer. Therefore; new targets for chemo-preventive and therapeutic agents need to be identified.Triptolide (TL), extracts of the Chinese herb Tripterygium Wilfordii hook have potent anti-inflammatory and immunosuppressive properties and have been used successfully in traditional Chinese medicine for the treatment of rheumatoid arthritis and lupus erythematosus[5,6]. It has been recently reported that TL possesses anti-tumor and proapoptotic activities in many different tumor cell lines, including breast, prostate, lung, and leukemia cells lines[7–13]. TL was also shown to sensitize cells to death induced by a variety of agents, such as Apo2/Trail, TNF-α, and different chemotherapeutic agents[14–16]. In this study, we provide evidence that TL potently inhibits human pancreatic cancer cell lines growth in vitro, suggesting that TL could be used to prevent or treat pancreatic cancer in the future. Considerable studies indicated that TL functioned through a p53-dependent or independent way[11,14,17,18]. Recently, Bing et al suggested that TL induced caspase-dependent cell death via the mitochondrial pathway in leukemia cells. However, the cellular and molecular mechanisms underlying TL-induced apoptosis in tumor cells are not fully understood.The purpose of this study is to investigate the inhibitory effects of TL on apoptosis and angiogenesis of pancreatic cancer in vitro and further to explore whether TL exerts clinical therapeutic value for patients with pancreatic cancer.
RESULTS: TL inhibited the growth of human pancreatic cancer cells in a dose-and time-dependent manner. TL induced human pancreatic cancer cells to undergo apoptosis with typically apoptotic characteristics. TUNEL assay showed that after the treatment of human pancreatic cancer cells with 40 ng/mL TL for 12 h and 24 h, the apoptotic rates of human pancreatic cancer cells increased significantly. RT-PCR demonstrated that caspase-3 and bax were significantly up-regulated in SW1990 cells treated with TL while bcl-2 mRNA was not.
CONCLUSION: TL is able to induce the apoptosis in human pancreatic cancer cells. This apoptosis may be mediated by up-regulating the expression of apoptosis-associated caspase-3 and bax gene.