Presence Of Triptolide Research Articles

Triptolide enhances carboplatin-induced apoptosis by inhibiting nucleotide excision repair (NER) activity in melanoma.

Introduction: Carboplatin (CBP) is a DNA damaging drug used to treat various cancers, including advanced melanoma. Yet we still face low response rates and short survival due to resistance. Triptolide (TPL) is considered to have multifunctional antitumor effects and has been confirmed to enhance the cytotoxic effects of chemotherapeutic drugs. Herein, we aimed to investigate the knowledge about the effects and mechanisms for the combined application of TPL and CBP against melanoma. Methods: Melanoma cell lines and xenograft mouse model were used to uncover the antitumor effects and the underlying molecular mechanisms of the alone or combined treatment of TPL and CBP in melanoma. Cell viability, migration, invasion, apoptosis, and DNA damage were detected by conventional methods. The rate-limiting proteins of the NER pathway were quantitated using PCR and Western blot. Fluorescent reporter plasmids were used to test the NER repair capacity. Results: Our results showed that the presence of TPL in CBP treatment could selectively inhibit NER pathway activity, and TPL exerts a synergistic effect with CBP to inhibit viability, migration, invasion, and induce apoptosis of A375 and B16 cells. Moreover, combined treatment with TPL and CBP significantly inhibited tumor progression in nude mice by suppressing cell proliferation and inducing apoptosis. Discussion: This study reveals the NER inhibitor TPL which has great potential in treating melanoma, either alone or in combination with CBP.

Mechanisms of action of triptolide against colorectal cancer: insights from proteomic and phosphoproteomic analyses

Triptolide is a potent anti-inflammatory agent that also possesses anticancer activity, including against colorectal cancer (CRC), one of the most frequent cancers around the world. In order to clarify how triptolide may be effective against CRC, we analyzed the proteome and phosphoproteome of CRC cell line HCT116 after incubation for 48 h with the drug (40 nM) or vehicle. Tandem mass tagging led to the identification of 403 proteins whose levels increased and 559 whose levels decreased in the presence of triptolide. We also identified 3,110 sites in proteins that were phosphorylated at higher levels and 3,161 sites phosphorylated at lower levels in the presence of the drug. Analysis of these differentially expressed and/or phosphorylated proteins showed that they were enriched in pathways involving ribosome biogenesis, PI3K−Akt signaling, MAPK signaling, nucleic acid binding as well as other pathways. Protein–protein interactions were explored using the STRING database, and we identified nine protein modules and 15 hub proteins. Finally, we identified 57 motifs using motif analysis of phosphosites and found 16 motifs were experimentally verified for known protein kinases, while 41 appear to be novel. These findings may help clarify how triptolide works against CRC and may guide the development of novel treatments.

STUDIES ON THE INTERACTION BETWEEN TRIPTOLIDE AND BOVINE SERUM ALBUMIN (BSA) BY SPECTROSCOPIC AND MOLECULAR MODELING METHODS.

Background:Triptolide is a major active constituent isolated from Tripterygiumwilfordii Hook F, a Chinese herbal medicine. This study investigated the intermolecular interaction between triptolide and bovine serum albumin (BSA).Materials and Methods:The fluorescence, circular dichroism (CD) and molecular docking methods were used to investigate the intermolecular interaction between triptolide and BSA. The binding constant, the number of binding sites, binding subdomain and the thermodynamic parameters were measured.Results:The results of this experiment revealed that the intrinsic fluorescence of BSA was effectively quenched by triptolide via static quenching. The experimental results of synchronous fluorescence and CD spectra showed that the conformation of BSA was changed in the presence of triptolide.Conclusion:It indicated that triptolide could spontaneously bind on site II (subdomain IIIA) of BSA mainly via hydrogen bonding interactions and Van der Waals force.

Triptolide enhances the tumoricidal activity of TRAIL against renal cell carcinoma.

Renal cell carcinoma (RCC) is resistant to traditional cancer therapies, and metastatic RCC (mRCC) is incurable. The shortcomings in current therapeutic options for patients with mRCC provide the rationale for the development of novel treatment protocols. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has proven to be a potent inducer of tumor cell death in vitro and in vivo, and a number of TRAIL death receptor agonists (recombinant TRAIL or TRAIL death receptor-specific mAb) have been developed and tested clinically. Unfortunately the clinical efficacy of TRAIL has been underwhelming and is likely due to a number of possible mechanisms that render tumors resistant to TRAIL, prompting the search for drugs that increase tumor cell susceptibility to TRAIL. The objective of this study was to determine the effectiveness of combining the diterpene triepoxide triptolide, or its water-soluble prodrug, Minnelide, with TRAIL receptor agonists against RCC in vitro or in vivo, respectively. TRAIL-induced apoptotic death of human RCC cells was increased in the presence of triptolide. The triptolide-induced sensitization was accompanied by increased TRAIL-R2 (DR5) and decreased heat shock protein 70 expression. In vivo treatment of mice bearing orthotopic RCC (Renca) tumors showed the combination of Minnelide and agonistic anti-DR5 mAb significantly decreased tumor burden and increased animal survival compared to either therapy alone. Our data suggest triptolide/Minnelide sensitizes RCC cells to TRAIL-induced apoptosis through altered TRAIL death receptor and heat shock protein expression.

Triptolide inhibits human immunodeficiency virus type 1 replication by promoting proteasomal degradation of Tat protein.

BackgroundPlants remain an important source of new drugs, new leads and new chemical entities. Triptolide is a diterpenoid epoxide isolated from Tripterygium wilfordii Hook F that possesses a broad range of bioactivities, including anti-inflammatory, immunosuppressive and anti-tumor properties. The antiviral activity of triptolide against human immunodeficiency virus type 1 (HIV-1) has not been reported.ResultsIn this study, nanomolar concentrations of triptolide were shown to potently inhibit HIV-1 replication in vitro. To identify the step(s) of the HIV-1 replication cycle affected by triptolide, time-of-addition studies, PCR analysis and direct transfection of viral genomic DNA were performed. The results of these experiments indicated that triptolide acts at the stage of viral gene transcription. In addition, a luciferase-based reporter assay that allows quantitative analysis of long terminal repeat (LTR)-driven transcription showed that Tat-induced LTR activation was impaired in the presence of triptolide. Moreover, Western blot analysis of exogenous gene expression (driven by the human elongation factor 1 α subunit promoter) in transiently transfected cells revealed that triptolide specifically reduces the steady-state level of Tat protein, without suppressing global gene expression. Further studies showed that triptolide accelerates Tat protein degradation, which can be rescued by administration of the proteasome inhibitor MG132. Mutation analysis revealed that N-terminal domains of Tat protein and nuclear localization are required for triptolide to reduce steady-state level of Tat.ConclusionThis study suggests for the first time that triptolide exerts its anti-HIV-1 activity by specifically prompting the degradation of the virally encoded Tat protein, which is a novel mechanism of action for an anti-HIV-1 compound. This compound may serve as a starting point for developing a novel HIV-1 therapeutic approach or as a basic research tool for interrogating events during viral replication.

Abstract 5110: The role triptolide in sensitizing lung tumor cells to cisplatin-induced apoptosis

Abstract Cisplatin is an anticancer drug used in treatment for many types of cancer, including lung cancer. The quick development of tumor cell drug resistance, however, greatly hindered the effectiveness of cisplatin in cancer treatment. Exploring new strategies that can sensitize tumor cells to cisplatin treatment, therefore, is essential for improving the effectiveness of cisplatin in cancer treatment. Triptolide is a bioactive ingredient isolated from Tripterygium wilfordii, a traditional Chinese herbal medicine that has been used to treat immune-related disorders. Recent studies revealed that Triptolide possesses potent antitumor properties through CDK7-depedent RNA polymerase II (Pol II) degradation and global transcription inhibition by binding to the XPB subunit of general transcription factor TFIIH and inhibiting its ATPase activity. We have studied the possibility of using Triptolide to sensitize lung tumor cell to cisplatin-induced apoptosis. Using both HTB182 and CRL5985 lung tumor cells, our caspase 3 activation studies demonstrated that the presence of low-level Triptolide greatly sensitized these lung tumor cells to cisplatin-induced apoptosis. Our western blots results indicated that the presence of low-level Triptolide increased the cisplatin-induced expression of PUMA but reduced expression of Bcl-XL in these lung tumor cells. Our immune-blotting studies revealed that the RNA Pol II level was not significantly affected by the presence of low-level Triptolide. Our real time PCR studies results indicated that expression levels of several tested genes also were not affected by the presence of Triptolide. These results suggest that the presence of low levels of triptolide sensitizes the lung cancer cells to cisplatin-induced apoptosis through binding to XPB of the TFIIH and inhibiting the DNA repair activity for cisplatin DNA damage, resulting in increased apoptosis of the lung tumor cells. Therefore, the presence of low levels of triptolide sensitizes lung tumor cells to cisplatin-induced apoptosis. Citation Format: Gan Wang, Xiaoxin Susan Xu, Yi Zhang. The role triptolide in sensitizing lung tumor cells to cisplatin-induced apoptosis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5110. doi:10.1158/1538-7445.AM2014-5110

Triptolide inhibits human immunodeficiency virus type 1 replication by promoting proteasomal degradation of Tat protein

Plants remain an important source of new drugs, new leads and new chemical entities. Triptolide is a diterpenoid epoxide isolated from Tripterygium wilfordii Hook F that possesses a broad range of bioactivities, including anti-inflammatory, immunosuppressive and anti-tumor properties. The antiviral activity of triptolide against human immunodeficiency virus type 1 (HIV-1) has not been reported. In this study, nanomolar concentrations of triptolide were shown to potently inhibit HIV-1 replication in vitro. To identify the step(s) of the HIV-1 replication cycle affected by triptolide, time-of-addition studies, PCR analysis and direct transfection of viral genomic DNA were performed. The results of these experiments indicated that triptolide acts at the stage of viral gene transcription. In addition, a luciferase-based reporter assay that allows quantitative analysis of long terminal repeat (LTR)-driven transcription showed that Tat-induced LTR activation was impaired in the presence of triptolide. Moreover, Western blot analysis of exogenous gene expression (driven by the human elongation factor 1 α subunit promoter) in transiently transfected cells revealed that triptolide specifically reduces the steady-state level of Tat protein, without suppressing global gene expression. Further studies showed that triptolide accelerates Tat protein degradation, which can be rescued by administration of the proteasome inhibitor MG132. Mutation analysis revealed that N-terminal domains of Tat protein and nuclear localization are required for triptolide to reduce steady-state level of Tat. This study suggests for the first time that triptolide exerts its anti-HIV-1 activity by specifically prompting the degradation of the virally encoded Tat protein, which is a novel mechanism of action for an anti-HIV-1 compound. This compound may serve as a starting point for developing a novel HIV-1 therapeutic approach or as a basic research tool for interrogating events during viral replication.

Possible involvement of mitogen-activated protein kinase phosphatase-1 (MKP-1) in thyrotropin-releasing hormone (TRH)-induced prolactin gene expression

The role of extracellular signal-regulated kinase (ERK) in mediating the ability of thyrotropin-releasing hormone (TRH) to stimulate the prolactin gene has been well elucidated. ERK is inactivated by a dual specificity phosphatase, mitogen-activated protein kinase phosphatase (MKP). In this study, we examined the induction of MKP-1 protein by thyrotropin-releasing hormone (TRH) in pituitary GH3 cells, and investigated the possible role for MKP-1 in TRH-induced prolactin gene expression. MKP-1 protein was induced significantly from 60 min after TRH stimulation, and remained elevated at 4 h. The effect of TRH on MKP-1 expression was completely prevented in the presence of the MEK inhibitor, U0126. In the experiments using triptolide, a potent blocker for MKP-1, MKP-1 induction by TRH was completely inhibited in a dose-dependent manner. TRH-induced ERK activation was significantly enhanced in this condition. Prolactin promoter activity, activated by TRH, was reduced to the control level in the presence of triptolide in a dose-dependent manner. In GH3 cells, which were transfected with MKP-1 specific siRNA, both the basal and TRH-stimulated activities of the prolactin promoter were significantly reduced compared to the cells transfected with negative control siRNA. Our present results support a critical role of MKP-1 in TRH-induced, ERK-dependent, prolactin gene expression.

Downregulation of lymphocyte activity and human synovial fibroblast growth in rheumatoid arthritis by triptolide

The antirheumatic effects of triptolide, a purified component derived from a Chinese herb, Tripterygium wilfordii Hook f. (TWH), was examined. Peripheral blood mononuclear cells (PBMC), T cells, or human synovial fibroblasts isolated from healthy controls or rheumatoid arthritis (RA) patients were cultured in vitro in the absence or presence of triptolide. Estimated by ELISA, immunoglobulin synthesis in pokeweed mitogen or Staphylococcus aureus Cowan 1 strain stimulated PBMC was significantly impaired by triptolide in a concentration-dependent manner (1–10 nM). Similarly, proliferation of PBMC in response to phytohemagglutinin (PHA-M), interleukin-2, or phorbol 12-myristate 13-acetate (PMA)/ionomycin estimated by incorporation of [3H]-thymidine was inhibited by triptolide. Cell viability was not affected at the immunosuppressive concentrations of triptolide. No abnormality of intracellular Ca2+ flux as estimated by flow cytometry was detected in PHA-M-stimulated T cells by triptolide. Biosynthesis of cellular protein estimated by incorporation of [3H]-leucine was significantly reduced in PMA/ionomycin stimulated PBMC by triptolide at concentrations above 7.5 nM. Proliferation of human synovial fibroblasts as estimated by crystal violet staining was significantly inhibited by triptolide at 30 nM. The present data demonstrate that triptolide is a potent immunosuppressant and has an antiproliferative effect on synovial fibroblast. The immunosuppressive activity of triptolide is not due to cytotoxicity, nor is it targeted at the initial membrane signal transduction process and the generation of second messengers. Inhibition of cellular protein synthesis by triptolide during lymphocyte activation may account for its inhibitory activity. The precise mechanism of action of triptolide needs to be defined in order to develop improved versions of the molecule for the potential treatment of RA. Drug Dev. Res. 47:144–153, 1999. © 1999 Wiley-Liss, Inc.