Triptolide induces mitochondria-mediated apoptosis of Burkitt's lymphoma cell via deacetylation of GSK-3ß by increased SIRT3 expression.

Burkitt's lymphoma (BL) is a highly aggressive B-cell non-Hodgkin lymphoma with rapid growth and dissemination propensity. Triptolide (TP), an active component extracted from Chinese herb Tripterygium wilfordii Hook f., has broad-spectrum anti-tumor activities. This study aimed to explore the in vitro and in vivo anti-cancer effects of TP on BL and the potential molecular mechanisms. In this study, the in vitro anti-tumor activity of TP was determined by CCK-8 and flow cytometry assays in Raji, NAMALWA and Daudi cells. The expression of SIRT3, phosphorylation and acetylation of glycogen synthase kinase-3ß (GSK-3ß) were analyzed by Western blot assay. Moreover, we examined the mitochondrial membrane potential by JC-1 method and measured apoptosis related protein using Western blot assay. BL xenograft model in NOD/SCID mice were established to evaluate the in vivo anti-cancer effect of TP. We discovered that TP inhibited BL cell growth and induced apoptosis in a dose-dependent manner. Loss of SIRT3 provides growth advances for BL cells. However, TP could up-regulate SIRT3 expression, which resulted in suppression of BL cells proliferation. GSK-3ß was activated by SIRT3-mediated deacetylation, which subsequently induced mitochondrial translocation and accumulation of Bax and decrease of mitochondrial membrane potential. Anti-tumor studies in vivo showed that TP (0.36 mg/kg) inhibited the growth of BL xenografts in NOD/SCID mice with an inhibitory rate of 73.13%. Our data revealed that TP triggered mitochondrial apoptotic pathway in BL by increasing SIRT3 expression and activating SIRT3/GSK-3ß/Bax pathway. This study indicated that TP is a potential anti-cancer Chinese herbal medicine against BL.

Inhibition of glycogen synthase kinase 3beta ameliorates triptolide-induced acute cardiac injury by desensitizing mitochondrial permeability transition.

Triptolide (TP), a diterpene triepoxide, is a major active component of Tripterygium wilfordii extracts, which are prepared as tablets and has been used clinically for the treatment of inflammation and autoimmune disorders. However, TP's therapeutic potential is limited by severe adverse effects. In a previous study, we reported that TP induced mitochondria dependent apoptosis in cardiomyocytes. Glycogen synthase kinase-3ß (GSK-3ß) is a multifunctional serine/threonine kinase that plays important roles in the necrosis and apoptosis of cardiomyocytes. Our study aimed to investigate the role of GSK-3ß in TP-induced cardiotoxicity. Inhibition of GSK-3ß activity by SB 216763, a potent and selective GSK-3 inhibitor, prominently ameliorated the detrimental effects in C57BL/6J mice with TP administration, which was associated with a correction of GSK-3ß overactivity. Consistently, in TP-treated H9c2 cells, SB 216763 treatment counteracted GSK-3ß overactivity, improved cell viability, and prevented apoptosis by modulating the expression of Bcl-2 family proteins. Mechanistically, GSK-3ß interacted with and phosphorylated cyclophilin F (Cyp-F), a key regulator of mitochondrial permeability transition pore (mPTP). GSK-3ß inhibition prevented the phosphorylation and activation of Cyp-F, and desensitized mPTP. Our findings suggest that pharmacological targeting of GSK-3ß could represent a promising therapeutic strategy for protecting against cardiotoxicity induced by TP.

Resveratrol protects against triptolide-induced cardiotoxicity through SIRT3 signaling pathway in vivo and in vitro.

Clinical application of triptolide (TP), a main active ingredient of the traditional Chinese herb Tripterygium wilfordii Hook f. (TWHF), is limited by a series of severe toxicities, including cardiotoxicity. In previous studies, we found the activation of sirtuin 3 (SIRT3) attenuated TP-induced toxicity in cardiomyocytes. Resveratrol (RSV), a polyphenol from the skins of grapes and red wine, is an activator of SIRT3. The current study aimed to investigate the protective effect of RSV against TP-induced cardiotoxicity and the underlying mechanisms. Mice were treated with a single dose of TP (2.5 mg/kg) via the intragastric (i.g.) route. After 24 h, TP induced abnormal changes of serum biochemistry, activity decrease of antioxidant enzymes and damage of heart tissue such as myocardial fiber rupture, cell swelling and interstitial congestion. In contrast, administration with RSV (50 mg/kg i.g. 12 h before and 2 h after the administration of TP) attenuated the detrimental effects induced by TP in BALB/c mice. Moreover, the cardiomyocyte protective effects of RSV on TP-induced heart injury were associated with the activation of SIRT3 and its downstream targets. In vitro study also indicated that RSV counteracted TP-induced cardiotoxicity through SIRT3-FOXO3 signaling pathway in H9c2 cells. Collectively, these findings suggest the potential of RSV as a promising agent in protecting heart from TP-induced damage.

Triptolide impairs thioredoxin system by suppressing Notch1-mediated PTEN/Akt/Txnip signaling in hepatocytes.

Triptolide (TP) is the main ingredient of Chinese herb Tripterygium wilfordii Hook f. (TWHF). Despite of its multifunction in pharmaceutics, accumulating evidences showed that TP caused obvious hepatotoxicity in clinic. The current study investigated the role of Notch1 signaling in TP-induced hepatotoxicity. Our data indicated that TP inhibited the protein expression of Notch1 and its active form Notch intracellular domain (NICD) leading to increased PTEN (phosphatase and tensin homolog deleted on chromosome ten) expression. Moreover, PTEN triggered Txnip (thioredoxin-interacting protein) activation by inhibiting Akt phosphorylation, which resulted in reduction of Trx (thioredoxin). In conclusion, TP caused liver injury through initiating oxidative stress in hepatocyte. This study indicated the potency of Notch1 to protect against TP-induced hepatotoxicity.

Triptolide-induced mitochondrial damage dysregulates fatty acid metabolism in mouse sertoli cells.

Triptolide is a major active ingredient of tripterygium glycosides, used for the therapy of immune and inflammatory diseases. However, its clinical applications are limited by severe male fertility toxicity associated with decreased sperm count, mobility and testicular injures. In this study, we determined that triptoide-induced mitochondrial dysfunction triggered reduction of lactate and dysregulation of fatty acid metabolism in mouse Sertoli cells. First, triptolide induced mitochondrial damage through the suppressing of proliferator-activated receptor coactivator-1 alpha (PGC-1α) activity and protein. Second, mitochondrial damage decreased lactate production and dysregulated fatty acid metabolism. Finally, mitochondrial dysfunction was initiated by the inhibition of sirtuin 1 (SIRT1) with the regulation of AMP-activated protein kinase (AMPK) in Sertoli cells after triptolide treatment. Meanwhile, triptolide induced mitochondrial fatty acid oxidation dysregulation by increasing AMPK phosphorylation. Taken together, we provide evidence that the mechanism of triptolide-induced testicular toxicity under mitochondrial injury may involve a metabolic change.

Activation of SIRT3 attenuates triptolide-induced toxicity through closing mitochondrial permeability transition pore in cardiomyocytes.

Triptolide (TP), an active component of the traditional Chinese herb Tripterygium wilfordii Hook f. (TWHF), has multiple pharmacological effects. However, the severe toxicity of TP greatly restricts its clinical applications. Although TP exposure causes serious heart injury, the mechanism underlying TP-induced cardiotoxicity has rarely been investigated. In previous studies, we found that TP-induced oxidative stress was involved in the mitochondria-dependent apoptosis of cardiomyocytes. Opening of the mitochondrial permeability transition pore (mPTP) is the key to the mitochondrial dysfunction in cardiac toxicity. The aim of this study was to investigate the potential cardioprotective effects of sirtuin 3 (SIRT3) on the mPTP. In the present study, the cytotoxicity of TP was accompanied by the up-regulation of the SIRT3 protein level and its rapid aggregation in nuclei and mitochondria. The SIRT3-FOXO3 signaling pathway was activated simultaneously, resulting in increased transcription of manganese superoxide dismutase (MnSOD) and catalase (CAT) for the elimination of reactive oxygen species (ROS). In addition, augmentation of the SIRT3 level via the overexpression plasmid SIRT3-Flag provided resistance to TP-induced cellular damage, whereas knocking down the SIRT3 level via siRNA accelerated the damage. Because it is an activator of SIRT3, the protective effect of resveratrol was also evaluated in H9c2 cells. In conclusion, the current results suggest that activation of SIRT3 substantially ameliorates the detrimental effects of TP by closing the mPTP.