Triptolide induces cell death in pancreatic cancer cells by apoptotic and autophagic pathways.
ABSTRACT Pancreatic adenocarcinoma, among the most lethal human malignancies, is resistant to current chemotherapies. We previously showed that triptolide inhibits the growth of pancreatic cancer cells in vitro and prevents tumor growth in vivo. This study investigates the mechanism by which triptolide kills pancreatic cancer cells.
Cells were treated with triptolide and viability and caspase-3 activity were measured using colorimetric assays. Annexin V, propidium iodide, and acridine orange staining were measured by flow cytometry. Immunofluorescence was used to monitor the localization of cytochrome c and Light Chain 3 (LC3) proteins. Caspase-3, Atg5, and Beclin1 levels were down-regulated by exposing cells to their respective short interfering RNA.
We show that triptolide induces apoptosis in MiaPaCa-2, Capan-1, and BxPC-3 cells and induces autophagy in S2-013, S2-VP10, and Hs766T cells. Triptolide-induced autophagy has a pro-death effect, requires autophagy-specific genes, atg5 or beclin1, and is associated with the inactivation of the Protein kinase B (Akt)/mammalian target of Rapamycin/p70S6K pathway and the up-regulation of the Extracellular Signal-Related Kinase (ERK)1/2 pathway. Inhibition of autophagy in S2-013 and S2-VP10 cells results in cell death via the apoptotic pathway whereas inhibition of both autophagy and apoptosis rescues cell death.
This study shows that triptolide kills pancreatic cancer cells by 2 different pathways. It induces caspase-dependent apoptotic death in MiaPaCa-2, Capan-1, and BxPC-3, and induces caspase-independent autophagic death in metastatic cell lines S2-013, S2-VP10, and Hs766T, thereby making it an attractive chemotherapeutic agent against a broad spectrum of pancreatic cancers.
- SourceAvailable from: Reginald HalabyJournal of Molecular Biology and Molecular Imaging. 12/2014; 1(1):3-2014.
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ABSTRACT: Sorafenib is the only drug approved by the Food and Drug Administration for metastatic hepatocellular carcinoma (HCC). Triptolide, a diterpene triepoxide, exhibits antineoplastic properties in multiple tumor cell types. In this study, we examined the effects of these agents and their combination on HCC in vitro and in vivo models.Surgery 06/2014; · 3.37 Impact Factor
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ABSTRACT: Hepatocellular carcinoma (HCC) has one of the worst prognoses for survival as it is poorly responsive to both conventional chemotherapy and mechanism-directed therapy. This results from a lack of therapeutic concentration in the tumor tissue coupled with the highly toxic off-site effects exhibited by these compounds. Consequently, we believe the best packaging for holistic therapy for HCC will involve three components: a potent therapeutic, a rationally designed drug delivery vehicle to enrich the target site concentration of the drug, and a surface ligand that can enable a greater propensity to internalization by tumor cells compared to the parenchyma. We screened a library containing hundreds of compounds against a panel of HCC cells and found the natural product, triptolide, to be more effective than sorafenib, doxorubicin, and daunorubicin, which are the current standards of therapy. However, the potential clinical application of triptolide is limited due to its poor solubility and high toxicity. Consequently, we synthesized tumor pH-sensitive nanoformulated triptolide coated with folate for use in an HCC-subpopulation that overexpresses the folate receptor. Our results show triptolide itself can prevent disease progression, but at the cost of significant toxicity. Conversely, our pH-sensitive nanoformulated triptolide facilitates uptake into the tumor, and specifically tumor cells, leading to a further increase in efficacy while mitigating systemic toxicity.ACS Nano 08/2014; · 12.03 Impact Factor