Diterpenoid Triepoxide Research Articles

Triptolide represses oral cancer cell proliferation, invasion, migration, and angiogenesis in co-inoculation with U937 cells

ObjectivesAdvanced oral cancer is a major public health concern because of a lack of effective prevention and treatment. Triptolide (TPL), a diterpenoid triepoxide derived from the Chinese herb Tripterygium wilfordii, has been demonstrated to possess strong anticancer properties. In this study, we investigated whether TPL exerts anticancer effects on the tumor microenvironment of head and neck squamous cell carcinoma (HNSCC).Materials and methodsHuman macrophage-like U937 cells were co-inoculated with oral cancer SAS cells in a noncontact transwell coculture system. Cytokine expression was detected using ELISA, and cell proliferation was detected using methylene blue. RNA levels were detected using qPCR. Protein levels were detected using Western blot analysis. In vivo experiments involved using xenografted NOD/SCID mice.ResultsOur results demonstrated that TPL inhibited the growth of SAS cells co-inoculated with U937 cells in vitro and in vivo. TPL inhibited the invasion, migration ability, and angiogenesis of SAS cells co-inoculated with U937 cells. Expression of cytokines IL-6, IL-8, and TNF-α was induced by co-inoculation, but TPL repressed their expression.ConclusionTPL suppressed the expression of cytokines IL-6, IL-8, and TNF-α, as well as tumor growth, invasion, migration, and angiogenesis in the co-inoculation of human tongue cancer cells with macrophage-like U937 cells.Clinical relevanceTPL is a potential candidate among novel chemotherapeutic agents or adjuvants for modulating tumor-associated macrophages in a tumor microenvironment of HNSCC.

Triptolide and its prodrug minnelide suppress Hsp70 and inhibit in vivo growth in a xenograft model of mesothelioma.

Malignant mesothelioma is a devastating disease with a poor prognosis for which there is a clear need for more successful therapeutic approaches. Triptolide, a diterpenoid triepoxide, is a highly effective agent against several cancer types in animal models. Owing to triptolide's poor solubility in water, a water-soluble analog, minnelide, was synthesized. Minnelide is a prodrug of triptolide and is activated by exposure to phosphatases that are found in all body tissues, including blood. Mesothelioma cells were treated in vitro with minnelide or its parent compound, triptolide. Minnelide and triptolide were both found to significantly reduce mesothelioma cell viability and induce apoptosis. The level of Hsp70, a protein that promotes cancer cell survival, was measured in mesothelioma cells before and after treatment with triptolide. Hsp70 levels were decreased in a dose-dependent manner. In addition, triptolide sensitized cells to gemcitabine and pemetrexed as measured by cell viability. Mice bearing mesothelioma flank tumors were treated with daily injections (28 d) of minnelide or saline solution and xenograft tumor growth recorded. Mice displayed significantly reduced tumor burden. These findings support the clinical evaluation of minnelide therapy for mesothelioma.

Triptolide to induce cell death of pancreatic cancer cells via inhibition of 14-3-3γ expression.

425 Background: Pancreatic cancer is one of the malignant tumors which exhibit resistance to chemotherapy. Gemcitabine-based therapy is a standard for advanced pancreatic cancer though it brings severe side-effect and average median survival is only 6 months. Hence increasing interest has focused on new agent with targeted therapies. Here we investigated the growth-inhibitory and apoptotic effect of triptolide, a diterpenoid triepoxide, and the role of 14-3-3γ expression in the apoptotic pathway induced by triptolide in human pancreatic cancer cells (AsPC-1 and PANC-1). Methods: Cell proliferation was measured by SRB, apoptotic cells were assessed by flow cytometry for Annexin V/PI staining and western blot for cleaved caspase-8, 9, 3 and fluorescent substrate assay for activities of caspase-8, 9, 3. To explore further mechanism of triptolide triggering death receptor pathway, specific siRNA targeted for 14-3-3γ was used to knock down 14-3-3γ expression measured by ELISA. In vivo, AsPC-1 xenografts in the absence or presence of stable down-regulation of 14-3-3γ expression by RNAi were treated with triptolide for 4 weeks and the tumor growth was compared, tumor samples were tested by ELISA and western blot for 14-3-3γ level. Results: Triptolide inhibits the proliferation at extremely low concentrations (12.5-50 nM) and induces apoptosis of pancreatic cancer cells through activating the caspase cascade associated with Bid cleavage. Moreover triptolide inhibited 14-3-3γ expression at dose and time-dependent manner and 14-3-3γ down-regulation sensitized cells to triptolide-induced apoptosis. Likewise, in vivo experiment of AsPC-1 xenografts, stable down-regulation of 14-3-3γ expression by RNAi significantly enhances triptolide-induced apoptosis and tumor growth delay. Conclusions: Triptolide exerted significant growth inhibitory effects and induced apoptosis in vitro and in vivo. Triptolide may have a potential to be an effective agent against pancreatic cancer and its mechanism of action is mediated by the inhibition of 14-3-3γ expression. The role of 14-3-3γ expression involved in resistance to apoptosis pathway make it be a potential therapeutic target in pancreatic cancer.

High effectiveness of triptolide, an active diterpenoid triepoxide, in suppressing Kir-channel currents from human glioma cells

Triptolide (Trip), a diterpene triepoxide isolated from medicinal vine Trypterygium wilfordii Hook. F. possessed multiple biological activities including antineoplastic actions. However, no report concerning its effects on ion currents has been published. In this study, we attempted to determine whether this compound has any effects on ion currents in malignant glioma cells. The mRNA expression of KCNJ10 (Kir4.1) was detected in U373 glioma cells. The inwardly rectifying K+ currents (IK(IR)) in U373 cells were almost fully blocked by BaCl2 (1mM). Trip (30nM–10μM) effectively decreased the amplitude of IK(IR) in a concentration-dependent manner with an IC50 value of 0.72μM. In chlorotoxin-treated U373 cells, Trip-mediated block of IK(IR) remained effective. Addition of Trip (3μM) slightly inhibited the amplitude of Ca2+-activated K+ current and sustained K+ outward current in U373 cells. In cell-attached configuration, when Trip was added to the bath, the activity of inwardly rectifying K+ (Kir) channels diminished with no change in single-channel conductance. Its suppression of Kir channels was accompanied by a reduction in the slow component of mean open time. Under current-clamp conditions, addition of Trip depolarized the membrane along with changes in frequency histogram of resting potential. Block by this component of Kir4.1 channels may be an important mechanism underlying its actions on the functional activity of glioma cells. Targeting at Kir4.1 channels may be clinically useful as an adjunctive regimen to anti-cancer drugs.

Triptolide inhibits MCF‐7 cell growth via estrogen receptor‐α‐related pathways (657.5)

Triptolide, a diterpenoid triepoxide from the traditional Chinese medicinal herb Tripterygium wilfordii Hook. f., is a potential treatment for autoimmune diseases as well a possible anti‐tumor agent. Our previous studies have shown that triptolide inhibits the proliferation of breast cancer cells in vitro and more potently reduces growth of estrogen receptor α (ERα)‐positive breast cancer cells than ERα‐negative cells. In this study, its ability to block the proliferation of breast cancer and its molecular mechanism of action were investigated. Methods: Cell viability was assessed by PrestoBlue assay. Real‐time PCR and western were used to determine ERα expression. To further investigate the effect of ERα on triptolide inhibition of cell growth, MDA‐MB‐231 cells that overexpress ERα were used. The MCF‐7 xenograft mouse tumor model was used to measure the effects of triptolide on breast cancer in vivo. Results:Levels of ERα and phosphorylated ERK were reduced by triptolide. Overexpression of ERα in MDA‐MB‐231 cells significantly enhanced triptolide’s inhibitory effects. In vivo tumor xenograft model, treatment of triptolide significantly reduced tumor size and ERα expression and inhibited phosphorylated ERK expression. Conclusions:This result suggests that triptolide might be a candidate for prevention of ER‐positive breast cancer cell lines.

Triptolide-induced in vitro and in vivo cytotoxicity in human breast cancer stem cells and primary breast cancer cells

We investigated the potential efficacy of the Chinese herbal extract triptolide for the treatment of human breast cancer by measuring the triptolide-induced cytotoxicity in cultures of human primary breast cancer cells (BCCs) and breast cancer stem cells (BCSCs) in vitro and in vivo. Human BCCs and BCSCs from invasive ductal carcinoma samples were cultured and treated with 0.1, 0.5 or 1.0 µM triptolide. Cell death and apoptosis were measured after 24, 48 and 72 h of treatment. Mammospheres were found to be highly tumorigenic when implanted subcutaneously in nude BALB/c mice. Triptolide was cytotoxic against both human primary BCCs and BCSCs in vitro (P<0.05), but the cytotoxicity was stronger against the BCCs. In response to 1 µM triptolide for 72 h, the apoptotic rates were approximately 60% for BCCs and 30% for BCSCs. The BCSCs exhibited a high formation rate of tumors when implanted subcutaneously in nude BALB/c mice. Triptolide treatment in vivo significantly inhibited tumor growth compared with mock treatment. In conclusion, the cytotoxicity of triptolide against BCCs and BCSCs in vitro and in vivo suggests that this natural diterpenoid triepoxide compound may have clinical applications for the suppression of breast tumor growth.

Nanostructured lipid carriers as a novel oral delivery system for triptolide: induced changes in pharmacokinetics profile associated with reduced toxicity in male rats

After oral administration in rodents, triptolide (TP), a diterpenoid triepoxide compound, active as anti-inflammatory, immunosuppressive, anti-fertility, anti-cystogenesis, and anticancer agent, is rapidly absorbed into the blood circulation (from 5.0 to 19.5 minutes after dosing, depending on the rodent species) followed by a short elimination half-life (from about 20 minutes to less than 1 hour). Such significant and rapid fluctuations of TP in plasma likely contribute to its toxicity, which is characterized by injury to hepatic, renal, digestive, reproductive, and hematological systems. With the aim of prolonging drug release and improving its safety, TP-loaded nanostructured lipid carriers (TP-NLCs), composed of Compritol® 888 ATO (solid lipid) and Capryol™ 90 (liquid lipid), were developed using a microemulsion technique. The formulated TP-NLCs were also characterized and in vitro release was evaluated using the dialysis bag diffusion technique. In addition, the pharmacokinetics and toxicology profiles of TP-NLCs were compared to free TP and TP-loaded solid lipid nanoparticles (TP-SLNs; containing Compritol 888 ATO only). Results demonstrate that TP-NLCs had mean particle size of 231.8 nm, increased drug encapsulation with a 71.6% efficiency, and stable drug incorporation for over 1-month. TP-NLCs manifested a better in vitro sustained-release pattern compared to TP-SLNs. Furthermore, TP-NLCs prolonged mean residence time (MRT)0–t (P<0.001, P<0.001), delayed Tmax (P<0.01, P<0.05) and decreased Cmax (P<0.01, P<0.05) compared to free TP and TP-SLNs, respectively, which was associated with reduced subacute toxicity in male rats. In conclusion, our data suggest that TP-NLCs are superior to TP-SLNs and could be a promising oral delivery system for a safer use of TP.

Triptolide induces apoptosis through the SERCA 3 upregulation in PC12 cells

Diterpenoid triepoxide - Triptolide (TTL) - increased protein levels of the noradrenaline transporter in three pheochromocytoma cell lines. This transporter is involved in the apoptosis induction through the inhibition of a transcription factor NF-kappa B. Nevertheless, calcium release from the endoplasmic reticulum can also induce inner mitochondrial pathway of apoptosis in variety of cells. Therefore, the aim of this work was to evaluate an involvement of calcium and, more specifically, the intracellular calcium transport systems in the apoptosis induction in pheochrocytoma cell line PC12. We observed significantly increased amount of reticular calcium in TTL-treated cells compared to control, untreated cells. Surprisingly, gene expression of the IP3 receptors was not changed after the TTL treatment, but ryanodine receptor of the type 2 (RyR2) was downregulated and sarco/endoplasmic reticulum calcium ATPase type 3 (SERCA 3) was upregulated in TTL- treated cells, compared to untreated controls. SERCA 3 blocking with the specific blocker thapsigargin prevented increase in apoptosis observed by the TTL treatment. Decrease in the ATP production by a replacement of glucose in the cultivation medium for its nonutilizable analog 2-deoxyglucose also prevented induction of the apoptosis in TTL-treated PC12 cells. Thus, these results suggest that upregulation of the SERCA 3 is ultimately involved in the TTL-induced apoptosis in PC12 cells.

Triptolide inhibits the multidrug resistance in prostate cancer cells via the downregulation of MDR1 expression

Triptolide (TPL) is a diterpenoid triepoxide derived from the Chinese herb Tripterygium wilfordii and possesses anti-tumor activity against a range of cancer cells. However, the effect of TPL on prostate cancer cells and its potential to overcome multidrug resistance (MDR) have not been explored. Therefore, in this study we used prostate cancer cell line DU145 as the experimental model and established DU145/ADM cell line resistant to adriamycin (ADM). Our results showed that TPL inhibited the proliferation and induced the cell cycle arrest and apoptosis of DU145 cells in a dose and time dependent manner. TPL decreased the levels of Cyclin D1 and anti-apoptotic protein Bcl-2, and increased the levels of pro-apoptotic proteins Fas and Bax. Furthermore, we found that TPL restored the sensitivity DU145/ADM cells to ADM in a dose dependent manner, and this was accompanied by the inhibition of MDR1 expression at both mRNA and protein levels. Taken together, these results provide strong evidence that TPL overcomes MDR in prostate cancer cells by downregulating MDR1 expression, and suggest that TPL is a promising agent for prostate cancer therapy, especially for chemoresistant prostate cancer.

Low-dose Triptolide in combination with Idarubicin could induce apoptosis in leukemia stem and progenitor cells via affecting the intrinsic and extrinsic factors

BackgroundRelapse has been a major hurdle for the success of acute myeloid leukemia chemotherapy, whereas leukemia stem cells (LSCs) have been considered to be responsible for relapse recently. Thus new drug targeting LSCs is urgently needed. Triptolide (TPL), a diterpenoid triepoxide derived from Tripterygium wilfordii, has been used in Traditional Chinese Medicine (TCM) for centuries. Recently, it has been reported that TPL has the potential of depleting quiescent CD34+ primitive CML progenitor cells. Moreover, normal CD34+ hemopoietic stem cells are less sensitive than AML blasts to TPL, suggesting the seclectivity of TPL in targeting LSCs. AimsIn this study, the ability of triptolide to induce apoptosis in leukemia stem and progenitor cells was investigated with the underlying mechanism being explored. MethodsLeukemia stem and progenitor cells were sorted from KG1a cells using flow cytometry with cell cycle being analyzed and then were subjected to different treatments and thereafter MTT assay, flow cytometry and Western blot or RT-PCR, intracellular ROS measurement colony forming assay were used to determine IC50, apoptotic status and expression of Nrf2, HIF-1α and their target genes, ROS level and colony forming ability. ResultsTPL is highly cytotoxic to leukemia stem and progenitor cells with IC20 of 5.0±0.81nM and IC50 of 20.48±1.6nM after 72h exposure. Leukemia stem and progenitor cells were also exposed to series concentrations of IDA with or without TPL(IC20F5.0nM). TPL significantly enhanced cytotoxicity of IDA to LSCs (IC50-IDA: 285.20±13.7 nM vs. IC50-IDA+TPL: 27.01±0.73 nM, P<0.001) Combination index was also analyzed. Results of combination index showed that synergism effect was observed over a wide range of IC50-IC90 concentrations of IDA and TPL in combination. Moreover, apoptotic ratio of cells treated by IDA with TPL was significantly increased compared to cells treated by IDA alone (24.85±1.70% vs. 76.87±8.34%, P<0.001). What's more, TPL in combination with IDA significantly inhibited the clonogenicity of leukemia stem and progenitor cells (-VE: 2097.3±106.07/well; TPL: 1387.7±40.05/well; IDA: 1252±46.87/well; TPL+IDA: 211±93.18/well, P<0.001). Next, we explore the underlying mechanism of TPL-induced apoptosis in LSCs. The survival of LSCs are dependent of intrinsic factors (Nrf2 and ROS) and extrinsic factors(HIF-1α, VLA4). Induction of ROS while inhibition of protective factor Nrf2 could lead to the apoptosis of LSCs. ROS activation was concentration-dependent when IDA was combined with a constant concentration of TPL (IC20:5nM). The highest activity of intracellular ROS appeared in IDA 200nM+TPL5nM group. Down-regulation of Nrf2 as well as its target genes such as NQO1, GSR and HO-1 was also observed in our study. Moreover, extrinsic factors such as HIF-1α and its down-stream genes such as BNIP3, VEGF and CAIX were also down-regulated in TPL with IDA group. Important extrinsic factors affecting the adhesion of LSCs such as VLA4 and CXCR4 were also down-regulated in TPL with IDA group. ConclusionOur findings indicate that the cytotoxicity of triptolide and the enhancing effect of triptolide on the cytotoxicity of idarubicin in leukemia stem and progenitor cells may be caused by affecting the intrinsic and extrinsic factors. Disclosures:No relevant conflicts of interest to declare.

Low-dose Triptolide could enhance the Idarubicin-induced apoptosis in KG1α cells through down-regulation of MDR1 and NF-κb

BackgroundTriptolide (TPL), a diterpenoid triepoxide derived from Tripterygium wilfordii, has been used in Traditional Chinese Medicine (TCM) for centuries. Recently, TPL has also been shown to have strong anti-cancer ability both in vitro and in vivo. It could induce apoptosis in a variety of cancer cell lines. However, the clinical applications of TPL are limited by its narrow therapeutic window and severe toxicity. Thus, the focus of study about TPL has been switched to the ability of low dose of TPL in enhancing the drug-induced apoptosis of cancer cells. KG1a cell line is a kind of cell line which has been demonstrated to have a certain proportion of leukemia stem cells which are responsible for the relapse of leukemia. Usage of this kind of cell line could resemble the relapse situation of patients. MDR1 and NF-ΚB are two important factors closely related to drug-resistance. Dow-regulation of these two genes could lead to the sensitization of cells to drugs. AimsThis study aims to explore whether low-dose TPL could enhance the Idarubicin-induced apoptosis in KG1a cells through down-regulation of MDR1 and NF-κB. MethodsHoechst 33342 staining and flow cytometry analysis were used to determine the ability of TPL in enhancing the Idarubicin-induced apoptosis in KG1a cells. RT-PCR as well as western blotting analysis were used to determine whether TPL combined with Idarubicin could down-regulate MDR1 and NF-κB. ResultsHoechst 33342 staining and flow cytometry analysis showed that low-dose of TPL((IC20F5.0nM)) could significantly enhance the Idarubicin-induced apoptosis in KG1a cells(Idarubicin alone vs Idarubicn combined with TPL: 15.13%: 60.17%; P<0.05). TPL combined with Idarubicin could down-regulate expression of MDR1 both at protein and mRNA level with the down-regulation of NF-κB at protein level. ConclusionLow-dose Triptolide could enhance the Idarubicin-induced apoptosis IN KG1a cells through down-regulation of MDR1 and NF-κB Disclosures:No relevant conflicts of interest to declare.

Anti-Angiogenic Effect of Triptolide in Rheumatoid Arthritis by Targeting Angiogenic Cascade

Rheumatoid arthritis (RA) is characterized by a pre-vascular seriously inflammatory phase, followed by a vascular phase with high increase in vessel growth. Since angiogenesis has been considered as an essential event in perpetuating inflammatory and immune responses, as well as supporting pannus growth and development of RA, inhibition of angiogenesis has been proposed as a novel therapeutic strategy for RA. Triptolide, a diterpenoid triepoxide from Tripterygium wilfordii Hook F, has been extensively used in treatment of RA patients. It also acts as a small molecule inhibitor of tumor angiogenesis in several cancer types. However, it is unclear whether triptolide possesses an anti-angiogenic effect in RA. To address this problem, we constructed collagen-induced arthritis (CIA) model using DA rats by the injection of bovine type II collagen. Then, CIA rats were treated with triptolide (11–45 µg/kg/day) starting on the day 1 after first immunization. The arthritis scores (P<0.05) and the arthritis incidence (P<0.05) of inflamed joints were both significantly decreased in triptolide-treated CIA rats compared to vehicle CIA rats. More interestingly, doses of 11∼45 µg/kg triptolide could markedly reduce the capillaries, small, medium and large vessel density in synovial membrane tissues of inflamed joints (all P<0.05). Moreover, triptolide inhibited matrigel-induced cell adhesion of HFLS–RA and HUVEC. It also disrupted tube formation of HUVEC on matrigel and suppressed the VEGF-induced chemotactic migration of HFLS–RA and HUVEC, respectively. Furthermore, triptolide significantly reduced the expression of angiogenic activators including TNF-α, IL-17, VEGF, VEGFR, Ang-1, Ang-2 and Tie2, as well as suppressed the IL1-β-induced phosphorylated of ERK, p38 and JNK at protein levels. In conclusion, our data suggest for the first time that triptolide may possess anti-angiogenic effect in RA both in vivo and in vitro assay systems by downregulating the angiogenic activators and inhibiting the activation of mitogen-activated protein kinase downstream signal pathway.

Effect of triptolide on gemcitabine-mediated apoptosis in pancreatic cancer cell lines.

e22043 Background: Pancreatic cancer is notorious for its resistance to anticancer drug. gemcitabine, the most effective anticancer drug currently available for palliative chemotherapy in pancreatic cancer patients, hardly achieves clinically satisfactory response rates. Therefore, it is urgent to develop novel agents that overcome drug resistance of pancreatic cancer. In this study, we demonstrated for the first time that triptolide, a diterpenoid triepoxide purified from the Chinese herb Tripterygium wilfordii Hook F, can enhance gemcitabine-mediated apoptosis in human pancreatic cancer cell lines (AsPC-1 and PANC-1). Methods: Pancreatic cells were treated with gemcitabine or triptolide alone, and combination of them, cell viability was measured by MTT, and apoptotic cells were assessed by flow cytometry for Annexin V/PI staining and western blot for cleaved caspase-3, 8, 9 and PARP. To explore the mechanism of enhancement of triptolide and gemcitabine, proteomic approach was used to screen the related apoptosis factors. Results: Triptolide demonstrated toxicity on pancreatic cancer cell lines with the IC50 of 25-40 nM. The combination of triptolide (IC30 concentration) and gemcitabine enhanced the cytotoxicity significantly compared to gemcitabine alone. Combination index (CI) indicated the effect of triptolide plus gemcitabine was synergistic. Furthermore, pancreatic cancer cells treated with triptolide plus gemcitabine exhibited increased apoptosis, as evidenced by stronger Annexin V/ PI staining, higher levels of pro-apoptotic proteins including cleaved caspases and activated PARP compared to cells treated with gemcitabine alone. In the mechanism study, vimentin, a mesenchymal marker, was screened out to be correlated with enhanced apoptosis induced by triptolide plus gemcitabine. Conclusions: 1) Triptolide has a potent therapeutic effect on pancreatic cancer cell lines; 2) the combination of triptolide with gemcitabine enhances the apoptosis in vitro, low concentration of TPL showed synergistic effect with gemcitabine; 3) The enhanced apoptosis induced by triptolide plus gemcitabine is correlated with vimentin expression inhibited by triptolide.

Role of oxidative stress, endoplasmic reticulum stress and ERK activation in triptolide-induced apoptosis

Since its isolation from Tripterygium wilfordii in 1972, triptolide has been shown to possess potent anticancer activity against a variety of cancers, and has entered phase I clinical trial. It is a diterpenoid triepoxide that acts through multiple molecular targets and signaling pathways. The mitogen-activated protein kinases are well known for their modulation of cell survival and proliferation. In particular, the ERK pathway has a dual role in cell proliferation and cell death. Thus far, data on the effect of triptolide on ERK signaling remain limited. In our current study, we have shown for the first time that ERK activation rather than inhibition occurred in a dose- and time-dependent manner following triptolide treatment in MDA-MB-231 breast cancer cells. ERK activation was crucial in mediating triptolide-induced caspase-dependent apoptosis. Tritpolide-induced ERK activation modulated the expression of the Bcl-2 protein family member Bax but was not involved in the downregulation of Bcl-xL expression. Signals acted upstream of ERK activation included generation of reactive oxygen species (ROS) and endoplasmic reticulum stress predominantly via the PERK‑eIF2α pathway, as the MEK inhibitor U0126 did not inhibit the phosphorylation of PERK and eIF2α or the generation of ROS.

Triptolide triggers the apoptosis of pancreatic cancer cells via the downregulation of Decoy receptor 3 expression

Triptolide (TPL) is a diterpenoid triepoxide that effectively induces apoptosis in a wide variety of cancer cells. However, the detailed mechanism by which TPL activates caspase cascade remains elusive. This study aimed to examine the antitumor effects of TPL against pancreatic cancer and investigate the underlying mechanism. Cell proliferation was evaluated by sulforhodamine B assay. The apoptosis was evaluated by caspase activity assay, Western blot and flow cytometry. DcR3 level was measured by ELISA. AsPC-1 xenografts were established to compare the in vivo antitumor effects of TPL and Gemcitabine. TPL inhibited the proliferation and induced the apoptosis of pancreatic cancer cells in a dose- and time-dependent manner. TPL also inhibited DcR3 expression in a dose- and time-dependent manner. siRNA-mediated DcR3 knockdown sensitized pancreatic cancer cells to TPL-induced apoptosis. In vivo, DcR3 siRNA significantly enhanced TPL-induced apoptosis and tumor growth inhibition. Moreover, TPL showed less toxicity compared to Gemcitabine in mice model. TPL induces the apoptosis of pancreatic cancer cells via the downregulation of DcR3 expression and has the potential as an effective agent against pancreatic cancer.

Triptolide inhibits colon cancer cell proliferation and induces cleavage and translocation of 14‐3‐3 epsilon

Triptolide is a diterpenoid triepoxide derived from the traditional Chinese medical herb Tripterygium wilfordii. In the present study, we demonstrated that this phytochemical attenuated colon cancer growth in vitro and in vivo. Using a proteomic approach, we found that 14-3-3 epsilon, a cell cycle- and apoptosis-related protein, was altered in colon cancer cells treated with triptolide. In this regard, triptolide induced cleavage and perinuclear translocation of 14-3-3 epsilon. Taken together, our findings suggest that triptolide may merit investigation as a potential therapeutic agent for colon cancer, and its anticancer action may be associated with alteration of 14-3-3 epsilon.

Triptolide: structural modifications, structure–activity relationships, bioactivities, clinical development and mechanisms

Triptolide, a principal bioactive ingredient of Tripterygium wilfordii Hook F, has attracted extensive exploration due to its unique structure of a diterpenoid triepoxide and multiple biological activities. This review will focus on the structural modifications, structure-activity relationships, pharmacology, and clinical development of triptolide in the last forty years.

Triptolide protects mice from ischemia/reperfusion injury by inhibition of IL-17 production

Ischemia and reperfusion have been identified as a complex cascade of inflammatory mediators that are involved in the pathogenesis of hepatic injury. Triptolide (diterpenoid triepoxide), was extracted from a purified component of a traditional Chinese Medicine, Tripterygium wilfondii Hook F. Currently, triptolide has been shown to have anti-inflammatory, immunosuppressive, and antineoplastic activity. Accumulated data have shown that Th17 cells might contribute to the pathogenesis of liver diseases. Triptolide has been shown to reduce interleukin (IL)-17 expression in inflammatory bowel disease and arthritis. However, the role of triptolide in liver ischemia/reperfusion (I/R) and whether it can attenuate injury and the potential mechanism have not been investigated. Mice were treated with triptolide (0.1mg/kg) for 1week or IL-17 antibody (50μg/mouse) 2days before ischemic insult. Partial warm ischemia was produced in the hepatic lobes of C57BL/6 mice for 90min, followed by various periods of reperfusion. We demonstrated that IL-17 was involved in the inflammatory response to hepatic I/R injury, and that triptolide inhibited IL-17 generation and suppressed neutrophil migration after liver I/R injury through downregulation of signal transducer and activator of transcription 3 (STAT3) transcription. Also, triptolide pretreatment protected the liver from warm I/R injury, at least in part, mediated by the upregulation of Foxp3 expression. These results could pave the way for the use of triptolide as a novel agent to attenuate I/R injury.

Cytotoxicity of Triptolide and Triptolide loaded polymeric micelles in vitro

Triptolide (TP), a diterpenoid triepoxide purified from the Chinese herb Tripterygium wilfordii Hook F is characterized by strong anti-tumor effects on various cancer cells. Except its anti-tumor effects, TP also shows multiple pharmacological side activities, such as anti-inflammatory, immune-suppressive and male anti-fertility. In order to reduce these side effects, especially the immuno-suppressive activity when used to cure cancer, a novel polymeric micelle system containing TP (TP-PM) was constructed. The immune-modulation effects of TP-PM have been evaluated by previous studies. In this study, we compared the cytotoxicity of TP and TP-PM on Jurkat and HT29 cells. Therefore, we determined the cell viability, membrane integrity, cell proliferation, apoptosis, and caspase 3/7 activity after exposure to TP and TP-PM. The results demonstrated that actually low concentrated TP and TP-PM could induce an inhibition of cell growth and proliferation as well as membrane damage in both tumor cell lines. TP and TP-PM induced apoptosis and caused activation of caspase 3/7 even at low concentrations. Both formulations destroyed the membrane of Jurkat cells, nevertheless, TP-PM showed stronger pernicious effects. In general, TP-PM induced in both tested cell lines stronger effects than TP. Therefore, polymeric micelles can be considered as promising carriers for TP in cancer therapy.

Triptolide circumvents drug-resistant effect and enhances 5-fluorouracil antitumor effect on KB cells

Triptolide, a diterpenoid triepoxide derived from the Chinese herb Tripterygium wilfordii, exerts an antitumor effect in KB cancer cells through the induction of apoptosis. In this study, we show that triptolide possesses an anticancer effect on drug-sensitive parental KB cells and multidrug-resistant KB-7D and KB-tax cells that overexpress multidrug resistance protein and MDR, respectively. Our data revealed that triptolide decreases the expression of multidrug resistance protein and MDR in both KB-7D and KB-tax cells. It also induces apoptosis in these multidrug-resistant cancer cells by activating caspase-3, and decreasing Mcl-1 and XIAP. Triptolide not only inhibits tumor growth but also induces apoptosis of these drug-resistant cancer cells in xenograft mouse models. Moreover, we also show that triptolide combined with 5-fluorouracil could be an alternative strategy for chemotherapy enhancement. These results indicate the therapeutic value of triptolide on multidrug-resistant cells, and when combined with 5-fluorouracil for the enhancement of cancer therapy.