Triptolide inhibits transcription factor NF-kappaB and induces apoptosis of multiple myeloma cells

Jozimine A2, a Dimeric Naphthylisoquinoline (NIQ) Alkaloid, Shows In Vitro Cytotoxic Effects against Leukemia Cells through NF-κB Inhibition

Naphthylisoquinoline (NIQ) alkaloids are rising as a promising class of secondary metabolites with pharmaceutical potential. NF-κB has already been recognized as a significant modulator of cancer proliferation and drug resistance. We have previously reported the mechanisms behind the cytotoxic effect of dioncophylline A, an NIQ monomer, in leukemia cells. In the current study, we have investigated the cytotoxic effect of jozimine A2, an NIQ dimer, on leukemia cells in comparison to a second, structurally unsymmetric dimer, michellamine B. To this end, molecular docking was applied to predict the binding affinity of the dimers towards NF-κB, which was then validated through microscale thermophoresis. Next, cytotoxicity assays were performed on CCRF-CEM cells and multidrug-resistant CEM/ADR5000 cells following treatment. Transcriptome analysis uncovered the molecular networks affected by jozimine A2 and identified the cell cycle as one of the major affected processes. Cell death modes were evaluated through flow cytometry, while angiogenesis was measured with the endothelial cell tube formation assay on human umbilical vein endothelial cells (HUVECs). The results indicated that jozimine A2 bound to NF-κB, inhibited its activity and prevented its translocation to the nucleus. In addition, jozimine A2 induced cell death through apoptosis and prevented angiogenesis. Our study describes the cytotoxic effect of jozimine A2 on leukemia cells and explains the interactions with the NF-κB signaling pathway and the anticancer activity.

Mechanisms of cancer cell death induction by triptolide: A comprehensive overview

The need for naturally occurring constituents is driven by the rise in the cancer prevalence and the unpleasant side effects associated with chemotherapeutics. Triptolide, the primary active component of "Tripterygium Wilfordii", has exploited for biological mechanisms and therapeutic potential against various tumors. Based on the recent pre-clinical investigations, triptolide is linked to the induction of death of cancerous cells by triggering cellular apoptosis via inhibiting heat shock protein expression (HSP70), and cyclin dependent kinase (CDKs) by up regulating expression of P21. MKP1, histone methyl transferases and RNA polymerases have all recently identified as potential targets of triptolide in cells. Autophagy, AKT signaling pathway and various pathways involving targeted proteins such as A-disintegrin & metalloprotease-10 (ADAM10), Polycystin-2 (PC-2), dCTP pyro-phosphatase 1 (DCTP1), peroxiredoxin-I (Prx-I), TAK1 binding protein (TAB1), kinase subunit (DNA-PKcs) and the xeroderma-pigmentosum B (XPB or ERCC3) have been exploited. Besides that, triptolide is responsible for enhancing the effectiveness of various chemotherapeutics. In addition, several triptolide moieties, including minnelide and LLDT8, have progressed in investigations on humans for the treatment of cancer. Targeted strategies, such as triptolide conjugation with ligands or triptolide loaded nano-carriers, are efficient techniques to confront toxicities associated with triptolide. We expect and anticipate that advances in near future, regarding combination therapies of triptolide, might be beneficial against cancerous cells.

Triptolide increases resistance to bile duct ligation-induced liver injury and fibrosis in mice by inhibiting RELB

Cholestasis is a common, chronic liver disease that may cause fibrosis and cirrhosis. Tripterygium wilfordii Hook.f (TWHF) is a species in the Euonymus family that is commonly used as a source of medicine and food in Eastern and Southern China. Triptolide (TP) is an epoxy diterpene lactone of TWHF, as well as the main active ingredient in TWHF. Here, we used a mouse model of common bile duct ligation (BDL) cholestasis, along with cultured human intrahepatic biliary epithelial cells, to explore whether TP can relieve cholestasis. Compared with the control treatment, TP at a dose of 70 or 140 μg/kg reduced the serum levels of the liver enzymes alanine transaminase, aspartate aminotransferase, and alkaline phosphatase in mice; hematoxylin and eosin staining also showed that TP reduced necrosis in tissues. Both in vitro and in vivo analyses revealed that TP inhibited cholangiocyte proliferation by reducing the expression of RelB. Immunohistochemical staining of CK19 and Ki67, as well as measurement of Ck19 mRNA levels in hepatic tissue, revealed that TP inhibited the BDL-induced ductular reaction. Masson 3 and Sirius Red staining for hepatic hydroxyproline showed that TP alleviated BDL-induced hepatic fibrosis. Additionally, TP substantially inhibited BDL-induced hepatic inflammation. In summary, TP inhibited the BDL-induced ductular reaction by reducing the expression of RelB in cholangiocytes, thereby alleviating liver injury, fibrosis, and inflammation.

T4 reduces cisplatin resistance by inhibiting AEG-1 gene expression in lung cancer cells

Lung cancer is the most malignant form of cancer and has the highest morbidity and mortality worldwide. Due to drug resistance, the current chemotherapy for lung cancer is not effective and has poor therapeutic effects. Tripchlorolide (T4), a natural extract from the plant Tripterygium wilfordii, has powerful immunosuppressive and antitumour effects and may become a potential therapeutic agent for lung cancer. Therefore, this study aimed to investigate the effect of T4 on reducing chemoresistance in lung cancer cells and to explore the mechanism. 1. A549 and A549/DDP cells were separately transfected with AEG-1 overexpression and AEG-1 knockdown plasmids. A549/DDP cells were divided into the A549/DDP empty group, T4 group, and T4 + AEG-1 overexpression group. A CCK-8 assay was used to evaluate the proliferation of cells in each group. RT–qPCR and Western blotting were used to detect the expression of AEG-1 and MDR-1. Expression of AEG-1 in A549 and A549/DDP cells was positively correlated with cisplatin resistance. When the AEG-1 protein was overexpressed in A549 cells, the lethal effect of cisplatin on A549 cells was attenuated (all P < 0.05). After the AEG-1 protein was knocked down in A549/DDP cells, cisplatin was applied. The lethal effect was significantly increased compared to that in the corresponding control cells (all P < 0.05). AEG-1 protein expression gradually decreased with increasing T4 concentration in A549 and A549/DDP cells. Resistance to cisplatin was reduced after the addition of T4 to A549/DDP cells (P < 0.05), and this effect was enhanced after transfection with the AEG-1 knockdown plasmid. T4 plays an important role in increasing the sensitivity of lung cancer cells to cisplatin.

Triptolide targets super-enhancer networks in pancreatic cancer cells and cancer-associated fibroblasts

The tumor microenvironment in pancreatic ductal adenocarcinoma (PDAC) is highly heterogeneous, fibrotic, and hypovascular, marked by extensive desmoplasia and maintained by the tumor cells, cancer-associated fibroblasts (CAFs) and other stromal cells. There is an urgent need to identify and develop treatment strategies that not only target the tumor cells but can also modulate the stromal cells. A growing number of studies implicate the role of regulatory DNA elements called super-enhancers (SE) in maintaining cell-type-specific gene expression networks in both normal and cancer cells. Using chromatin activation marks, we first mapped SE networks in pancreatic CAFs and epithelial tumor cells and found them to have distinct SE profiles. Next, we explored the role of triptolide (TPL), a natural compound with antitumor activity, in the context of modulating cell-type-specific SE signatures in PDAC. We found that TPL, cytotoxic to both pancreatic tumor cells and CAFs, disrupted SEs in a manner that resulted in the downregulation of SE-associated genes (e.g., BRD4, MYC, RNA Pol II, and Collagen 1) in both cell types at mRNA and protein levels. Our observations suggest that TPL acts as a SE interactive agent and may elicit its antitumor activity through SE disruption to re-program cellular cross talk and signaling in PDAC. Based on our findings, epigenetic reprogramming of transcriptional regulation using SE modulating compounds such as TPL may provide means for effective treatment options for pancreatic cancer patients.

A review of the total syntheses of triptolide

Triptolide is a complex triepoxide diterpene natural product that has attracted considerable interest in the organic chemistry and medicinal chemistry societies due to its intriguing structural features and multiple promising biological activities. In this review, progress in the total syntheses of triptolide are systematically summarized. We hope to gain a better understanding of the field and provide constructive suggestions for future studies of triptolide.

Collateral Sensitivity of Parthenolide via NF-κB and HIF-α Inhibition and Epigenetic Changes in Drug-Resistant Cancer Cell Lines

Parthenolide (PT) is a sesquiterpene lactone isolated from Tanacetum parthenium. In this study, PT showed varying cytotoxic effects against different solid tumor cell lines. HCT116 (p53^+/+) colon carcinoma cells and their parental HCT116 knockout p53 (p53^-/-) cell lines showed a resistance degree of 2.36. On the other hand, wild-type U87.MG cells or cells transfected with a deletion-activated EGFR cDNA (U87.MGΔEGFR) exhibited slight sensitivity toward PT. Multidrug-resistant MDA-MB-231-BCRP cells were even more sensitive toward PT than sensitive MDA-MB-231-pcDNA cells with a resistance degree of 0.07 (collateral sensitivity). To the best of our knowledge, hypersensitivity (collateral sensitivity) in MDA-MB-231-BCRP cell line is reported in this study for the first time. We attempted to identify the mechanism of collateral sensitivity. Firstly, we found that PT bound to IKK preventing IκBα degradation and eventually inhibition of the nuclear factor kappa B (NF-κB) pathway. Down-regulation of hypoxia inducing factor 1-alpha (HIF-1α) in MDA-MB-231-BCRP resistant cells may be a second mechanism, since it is a target gene of NF-κB. Moreover, PT also showed epigenetic effect by inhibition of HDAC activity as shown using both molecular docking and HDAC activity assay. Based on COMPARE and hierarchical cluster analyses, we found gene expression profiles that predicted sensitivity or resistance of 47 tumor cell lines toward PT. Interestingly, pathway analyses of gene expression profiles revealed NF-κB and HIF signaling as top networks of these genes, cellular functions and canonical pathways influencing the activity of PT against tumor cells. In conclusion, PT exerted profound cytotoxic activity against various cancer cell lines mainly against BCRP-overexpressing tumor cells, suggesting PT as novel candidate for cancer treatment.

Effects of triptolide on bone marrow-derived mesenchymal stem cells from patients with multiple myeloma

Triptolide (TPL), an extract of the Chinese herb Tripterygium wilfordii Hook F, is a potent anti-inflammatory agent that further possesses anticancer activity. Its antiproliferative effects are well established. Only few studies have focused on TPL as a potential treatment in multiple myeloma (MM). In the current study, bone marrow-derived mesenchymal stem cells (BMMSCs) from patients with MM were isolated and treated with TPL at varying concentrations. Thalidomide is currently used as a positive control drug in the treatment of MM. Cell Counting kit-8 assays were performed to assess proliferation activity and flow cytometry with Annexin V-fluorescein/propidium iodide was used to detect cell apoptosis of TPL-treated BMMSCs. Reverse transcription-quantitative polymerase chain reaction assays were applied to measure interleukin (IL)-6, IL-1β and stem cell factor (SCF or Kit ligand) mRNA expression and western blot assays were performed to analyze transcription factor p65 (P65) expression in TPL-treated BMMSCs. ELISA was applied to measure vascular endothelial growth factor (VEGF) levels in the supernatant of the cultured and treated BMMSCs. TPL treatment significantly inhibited BMMSC proliferation compared with the untreated control (P<0.05). At 48 h following TPL treatment, a Cell Counting kit-8 study was performed and the IC₅₀ value was determined at 101.55±2.45 ng/ml. Apoptotic rates were observed to increase with increasing concentrations of TPL (P<0.001), and IL-6, IL-1β and SCF mRNA expression was significantly decreased with increasing TPL (P<0.001). P65 expression following TPL treatment was significantly decreased compared with the untreated control (P<0.05). VEGF levels were significantly reduced in the presence of increasing amounts of TPL (P<0.05). These findings suggest that TPL inhibited BMMSC growth and improved the bone marrow hematopoietic microenvironment by decreasing IL-6, IL-1β and SCF mRNA expression, subsequently inhibiting the proliferation of MM cells. Therefore, TPL may be used in the future to treat patients with MM.

Demethylzeylasteral inhibits glioma growth by regulating the miR-30e-5p/MYBL2 axis

Glioma is the most common and malignant form of primary brain tumour, and is characterised by high proliferation and extensive invasion and neurological destruction. Demethylzeylasteral (T-96), which is extracted from Tripterygium wilfordii, is considered to have immunosuppressive, anti-inflammatory and anti-angiogenic effects. Here, the anti-tumour effect of T-96 on glioma was evaluated. Our results demonstrated that T-96 significantly inhibited glioma cell growth and induced cell cycle arrest in G1 phase but did not induce apoptosis. Cell invasion and migration were dramatically suppressed after treatment with T-96. Almost all genes related to cell cycle and DNA replication were downregulated after treatment with T-96. Our results showed that miR-30e-5p was noticeably upregulated after T-96 treatment, and MYBL2, which is involved in cell cycle progression and is a target gene of miR-30e-5p, was significantly reduced in synchrony. Overexpression of MYBL2 partially rescued the T-96-induced inhibition of cell growth and proliferation. Moreover, a miR-30e-5p antagomir significantly reduced the upregulation of miR-30e-5p expression induced by T-96, leading to recovery of MYBL2 expression, and partially rescued the T-96-induced inhibition of cell growth and proliferation. More important, T-96 effectively upregulated miR-30e-5p expression and downregulated MYBL2 expression, thus inhibiting LN-229 cell tumour growth in a mouse model. These results indicated that T-96 might inhibit glioma cell growth by regulating the miR-30e-5p/MYBL2 axis. Our study demonstrated that T-96 might act as a promising agent for malignant glioma therapy.

Antitumor effect of triptolide in T-cell lymphoblastic lymphoma by inhibiting cell viability, invasion, and epithelial-mesenchymal transition via regulating the PI3K/AKT/mTOR pathway

INTRODUCTION

T-cell lymphoblastic lymphoma (T-LBL) is a widely disseminated disease worldwide. Triptolide (TPL) is purified from Chinese herb and displays anti-inflammatory, anti-fertility, anti-tumor and immunosuppressive effects.

MATERIALS AND METHODS

Here, in vitro and in vivo experiments were conducted to investigate the anti-tumor effect of TPL treatment in T-LBL and the potential mechanism in T-LBL progression.

RESULTS

TPL inhibited cell proliferation of T-LBL cells (Jurkat cells and Molt-3 cells) in a dose-dependent manner. Flow cytometry analysis showed that cell apoptosis rate was increased by TPL treatment. TPL also up-regulated the expression of Caspase-3, Bax and down-regulated the expression of Bcl-2, indicating that TPL promoted apoptosis in Jurkat cells. Moreover, TPL inhibited invasion ability of Jurkat cells and down-regulated the expression of MMP-3 and MMP-9 in a dose-dependent manner. The expression of Snail, Slug, Twist and Integrin αVβ6 was decreased and the expression of E-cadherin was increased by TPL treatment, indicating that TPL inhibited EMT of Jurkat cells. Apart from that, TPL treatment attenuated the phoslevels of PI3K, Akt and mTOR and suppressed AKT activation compared with control group, suggesting that TPL inhibited PI3K/Akt/mTOR signal pathway in T-LBL. In vivo experiments showed that TPL inhibited tumor growth of T-LBL and promoted apoptosis of tumor cells. The expression of PCNA, Bcl-2, Snail, p-PI3K, p-Akt and mTOR was suppressed by TPL in a dose-dependent manner, suggesting that TPL suppressed tumor growth and promoted apoptosis of tumor cells by inhibiting PI3K/Akt/mTOR signal pathway in T-LBL.

CONCLUSION

In conclusion, TPL exerted anti-tumor effect in T-LBL by inhibiting cell viability, invasion and EMT via regulating the PI3K/AKT/mTOR pathway.

Tripchlorolide induces autophagy in lung cancer cells by inhibiting the PI3K/AKT/mTOR pathway and improves cisplatin sensitivity in A549/DDP cells

Tripchlorolide (T4) has been shown to induce A549 lung cancer cell death predominantly by activating an autophagy pathway. However, the underlying mechanism remains unclear. Herein, we demonstrated that compared with T4 treatment alone, pretreatment with wortmannin (an inhibitor of phosphatidylinositol 3-kinase), perifosine (an inhibitor of AKT) or rapamycin (an inhibitor of mTOR) combined with a subsequent T4 treatment significantly impaired the cell viability of A549 and A549/DDP lung cancer cells. We found that either treatment scheme markedly reduced the activity of P13K and AKT. Expression of LC3II increased in parallel to the increase of the T4 concentration in both A549 and A549/DDP cells and was repressed by overexpression of AKT. The expression levels of PI3-K, PI3-P, AKT, TSC2, mTOR, p70S6K and 4E-BP1 were minimally affected by the wortmannin, perifosine, or rapamycin plus T4 treatments, but their phosphorylated products were greatly affected in A549 lung cancer cells and slightly affected in A549/DDP lung cancer cells. These results indicate that T4 induces autophagy in lung cancer cells by inhibiting the PI3K/AKT/mTOR signaling pathway. We further found that T4 decreased expression of MDR1 and improved cisplatin sensitivity of A549/DDP cells. Altogether, these results have meaningful implications for tumor therapy in the future.

"Heat shock protein 70 in pancreatic diseases: Friend or foe"

The heat shock response in pancreatitis that is activated via HSP70 protects acinar cells through multiple simultaneous mechanisms. It inhibits trypsinogen activation and modulates NF-κB signaling to limit acinar cell injury. On the other hand, HSP70 is overexpressed in pancreatic cancer and is hijacked by the cellular machinery to inhibit apoptosis. Inhibition of HSP70 in pancreatic cancer by a novel compound, Minnelide, has shown considerable clinical promise.

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.

Evidence that polycystins are involved in Hydra cnidocyte discharge

Like other cnidarians, the freshwater organism Hydra is characterized by the possession of cnidocytes (stinging cells). Most cnidocytes are located on hydra tentacles, where they are organized along with sensory cells and ganglion cells into battery complexes. The function of the battery complexes is to integrate multiple types of stimuli for the regulation of cnidocyte discharge. The molecular mechanisms controlling the discharge of cnidocytes are not yet fully understood, but it is known that discharge depends on extracellular Ca²⁺ and that mechanically induced cnidocyte discharge can be enhanced by the presence of prey extracts and other chemicals. Experiments in this paper show that a PKD2 (polycystin 2) transient receptor potential (TRP) channel is expressed in hydra tentacles and bases. PKD2 (TRPP) channels belong to the TRP channel superfamily and are non-selective Ca²⁺ channels involved in the transduction of both mechanical and chemical stimuli in other organisms. Non-specific PKD2 channel inhibitors Neo (neomycin) and Gd³⁺ (gadolinium) inhibit both prey capture and cnidocyte discharge in hydra. The PKD2 activator Trip (triptolide) enhances cnidocyte discharge in both starved and satiated hydra and reduces the inhibition of cnidocyte discharge caused by Neo. PKD1 and 2 proteins are known to act together to transduce mechanical and chemical stimuli; in situ hybridization experiments show that a PKD1 gene is expressed in hydra tentacles and bases, suggesting that polycystins play a direct or indirect role in cnidocyte discharge.

Nucleophosmin Mutations Induce Chemosensitivity in THP-1 Leukemia Cells by Suppressing NF-κB Activity and Regulating Bax/Bcl-2 Expression

Nucleophosmin (NPM1) - a gene that encodes for a nuclear protein with multiple functions. Mutations in NPM1 are seen in approximately one-third of acute myeloid leukemia (AML) and are generally associated with good response to induction chemotherapy. However, the mechanisms underlying this chemosensitivity are still unknown. Recent studies have established that nuclear factor-κB (NF-κB) activation is a key response of leukemia cell to chemotherapy. In this study, we transfected human monocytic leukemia THP-1 cells with the vector expressing NPM1 mutation variant (NPM1mA), and confirmed overexpression of NPM1mA at mRNA and protein levels by reverse transcription PCR (RT-PCR) and immunohistochemistry, respectively. The effects of NPM1 mutations on chemotherapeutical agents induced apoptosis, NF-κB activity and gene expression were examined using flow cytometry, luciferase reporter assays, quantitative real time PCR (qRT-PCR) and Western blot. We found that overexpression of NPM1mA in THP-1 cells sensitized these cells to apoptosis induced by chemotherapeutical agents such as daunorubicin (DNR) and cytarabine (Ara-C). Moreover, we demonstrated that expression of NPM1 mA reduced the NF-κB transcription activity of THP-1 cells upon drug treatment. In addition, restoration of NF-κB activity via TNF-α stimulation could attenuate the effect of NPM1mA overexpression on DNR-and Ara-C-induced apoptosis. Interestingly, expression of NPM1mA could upregulate Bax and downregulate Bcl-2 at mRNA and protein levels in THP-1 cells when treated with DNR or Ara-C. We also demonstrated that restoration of NF-κB activity via TNF-α pre-treatment reversed the effect of NPM1mA on the Bax/Bcl-2 expression. Furthermore, evaluation of gene expression data from The Cancer Genome Atlas (TCGA) dataset revealed that NPM1-mutated patients showed a higher expression of Bax and a lower expression of Bcl-2. These results suggest that the NPM1 gene mutations could confer increased sensitivity to chemotherapeutic agents, at least in part, by suppressing NF-κB activity and regulating Bax/Bcl-2 expression.

The triptolide derivative MRx102 inhibits Wnt pathway activation and has potent anti-tumor effects in lung cancer

BACKGROUND

The natural compound triptolide has been shown to decrease cell proliferation and induce apoptosis and cellular senescence. We previously demonstrated that triptolide decreases tumor formation and metastasis of human non-small cell lung cancer cells (NSCLC). Due to the toxicity of triptolide, derivatives of the natural compound have been developed that show more favorable toxicity profiles and pharmacokinetics in animal models. The purpose of this study was to evaluate MRx102 as a novel therapeutic for lung cancer.

METHODS

Mice injected subcutaneously with H460 lung cancer cells were treated with MRx102 or carboplatin to determine the effect of MRx102 on tumor formation in comparison to standard treatment. Patient-derived xenografts (PDX) with different WIF1 expression levels were treated with MRx102 or cisplatin. We tested the effects of MRx102 treatment on migration and invasion of lung cancer cells using Transwell filters coated with fibronectin and Matrigel, respectively. Tail vein injections using H460 and A549 cells were performed.

RESULTS

Here we report that the triptolide derivative MRx102 significantly decreases NSCLC proliferation and stimulates apoptosis. Further, MRx102 potently inhibits NSCLC haptotactic migration and invasion through Matrigel. In vivo, NSCLC tumor formation and metastasis were greatly decreased by MRx102 treatment. The decrease in tumor formation by MRx102 in the patient-derived xenograft model was WIF1-dependent, demonstrating that MRx102 is a potent inhibitor of the Wnt pathway in low WIF1 expressing NSCLC patient tumors.

CONCLUSIONS

These results indicate that MRx102 has potent antitumor effects both in vitro and in vivo, and is a potential novel therapy for the treatment of NSCLC.

Inhibitory Effect of Triptolide on Glioblastoma Multiforme In Vitro

This study investigated the effect of triptolide, derived from the traditional Chinese herb Tripterygium wilfordii, on the growth of glioblastoma multiforme (GBM) cells. Glioma cell lines U251MG and U87MG and normal human fetal astrocytes were exposed to various concentrations of triptolide, and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium and colony formation assays were used to measure cell growth and survival. Cell apoptosis was determined using annexin V. Levels of the oncogenic transformation-related proteins Ras-guanosine triphosphate (Ras-GTP), extracellular signal-regulated kinase (ERK) and Akt were determined by Western blotting. Triptolide caused a dose-dependent decrease in proliferation and increase in apoptosis in the glioma cell lines. Since U87MG has a wildtype p53 gene while U251MG harbours a mutated p53 gene, these results indicate that triptolide induces apoptosis in GBM cells via a p53-independent pathway. Treatment of GBM cells with triptolide attenuated both the Ras/ERK and the Ras/Akt signalling pathways. This could provide a theoretical basis for triptolide treatment in GBM, but further animal studies and clinical research are necessary.

The Effect of Triptolide on Apoptosis of Glioblastoma Multiforme (GBM) Cells

Triptolide, derived from the traditional Chinese herb, Tripterygium wilfordii, sensitizes cancer cells to apoptosis. Glioblastoma multiforme (GBM), which accounts for most cases of central nervous malignancy, has a very poor prognosis and lacks effective therapeutic inventions. We, therefore, investigated the effects of different concentrations of, and different periods of exposure to, triptolide on cell proliferation and apoptosis in the glioma cell lines, U251MG and U87MG, and in normal human fetal astrocytes. Cell proliferation was investigated by MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay and growth curve analysis, and apoptosis was assessed from genomic DNA fragmentation. Triptolide showed dose-dependent inhibition of cell proliferation and induction of apoptosis in glioma cells. It also increased the ratio of the pro-apoptotic protein, Bax, to the anti-apoptotic protein, Bcl-2. Since U87MG has the wild-type p53 gene whereas U251MG harbours a mutated p53 gene, our results indicate that triptolide induces apoptosis in GBM cells via a p53-independent pathway. The dose-dependent inhibition of cell proliferation and induction of apoptosis by triptolide may involve upregulation of Bax and downregulation of Bcl-2.

Pharmacogenomics of Scopoletin in Tumor Cells

Drug resistance and the severe side effects of chemotherapy necessitate the development of novel anticancer drugs. Natural products are a valuable source for drug development. Scopoletin is a coumarin compound, which can be found in several Artemisia species and other plant genera. Microarray-based RNA expression profiling of the NCI cell line panel showed that cellular response of scopoletin did not correlate to the expression of ATP-binding cassette (ABC) transporters as classical drug resistance mechanisms (ABCB1, ABCB5, ABCC1, ABCG2). This was also true for the expression of the oncogene EGFR and the mutational status of the tumor suppressor gene, TP53. However, mutations in the RAS oncogenes and the slow proliferative activity in terms of cell doubling times significantly correlated with scopoletin resistance. COMPARE and hierarchical cluster analyses of transcriptome-wide mRNA expression resulted in a set of 40 genes, which all harbored binding motifs in their promoter sequences for the transcription factor, NF-κB, which is known to be associated with drug resistance. RAS mutations, slow proliferative activity, and NF-κB may hamper its effectiveness. By in silico molecular docking studies, we found that scopoletin bound to NF-κB and its regulator IκB. Scopoletin activated NF-κB in a SEAP-driven NF-κB reporter cell line, indicating that NF-κB might be a resistance factor for scopoletin. In conclusion, scopoletin might serve as lead compound for drug development because of its favorable activity against tumor cells with ABC-transporter expression, although NF-κB activation may be considered as resistance factor for this compound. Further investigations are warranted to explore the full therapeutic potential of this natural product.

Triptolide suppresses proliferation, hypoxia-inducible factor-1α and c-Myc expression in pancreatic cancer cells

Triptolide (TL) is known to suppress the proliferation of a number of pancreatic cancer cell lines in vitro. Marked antitumor effects were also observed in a xenograft model of pancreatic cancer. Hypoxia‑inducible factor‑1α (HIF‑1α) is highly expressed in pancreatic cancer cells lines. The present study therefore tested the hypothesis that suppression of HIF‑1α is associated with the antitumor activity of TL. Quantitative polymerase chain reaction and western blot analysis were used to determine the level of gene expression. A xenograft tumor model of pancreatic cancer was established in athymic nude mice and the tumor size was measured to evaluate the outcome of TL treatment. Immunohistochemistry was used to detect the expression of HIF‑1α and vascular endothelial growth factor (VEGF), and to assess microvessel density. Microarray was used to investigate gene expression in pancreatic cancer cells following TL treatment. The expression of HIF‑1α was shown to be reduced in pancreatic cell lines following treatment with TL, and this effect occurred in a dose‑dependent manner. In a xenograft model of pancreatic cancer, reduced levels of HIF‑1α were also observed in mice that were treated with TL. Furthermore, the expression of VEGF, which is a direct target of HIF‑1α, was also suppressed, and the microvessel density of tumor tissues was consequently reduced. A microarray analysis of gene expression was performed in order to investigate the potential mechanisms underlying the antitumor activity of TL. The results showed that 11 genes, including c‑Myc, SOX9 and Ets2, were downregulated at an early stage following treatment with TL. A recent study indicated that overexpression of c‑Myc in colon cancer cells promotes increased expression of HIF‑1α and VEGF. Therefore, TL may suppress HIF‑1α through a c‑Myc‑dependent mechanism, which is involved in antitumor effects in mouse models of pancreatic cancer.

Protective effect of erythropoietin against myocardial injury in rats with sepsis and its underlying mechanisms

The aim of this study was to investigate the protective effect of erythropoietin (EPO) against acute myocardial injury and its underlying mechanisms. Mice (n=146) were randomly divided in a double-blind manner into four groups, sham, Rocephin, EPO and sepsis, and mortality was observed on the seventh day after cecal ligation and puncture. In addition, a total of 252 rats were randomly divided into three groups, sham, EPO and sepsis, and indicators of cardiac function, inflammatory mediators and serum creatine kinase levels were assessed. Mitochondrial membrane potential, cell apoptosis and nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) p65 expression levels were detected using flow cytometry. Following intervention with EPO, the mortality rate in mice with sepsis was significantly reduced and the cardiac function of septic rats was significantly improved. In addition, the levels of inflammatory mediators, serum creatine kinase and apoptosis and the myocardial mitochondrial membrane potential and expression of NF-κB p65 in cardiac tissue were all improved following EPO treatment, and the differences between the results for the sepsis and EPO groups were statistically significant (P<0.05). These findings suggest that EPO reduces the myocardial inflammatory response in septic rats, attenuates the reduction in mitochondrial membrane potential and inhibits myocardial cell apoptosis by reducing NF-κB p65 expression, and therefore exerts a protective effect in the myocardium.

Triptolide inhibits osteoclast formation, bone resorption, RANKL-mediated NF-қB activation and titanium particle-induced osteolysis in a mouse model

The RANKL-induced NF-κB signaling pathway is required for osteoclast formation and function. By screening for compounds that inhibit RANKL-induced NF-κB activation using a luciferase reporter gene assay in RAW264.7 cells, we identified triptolide (PG490), as a candidate compound targeting osteoclast differentiation and osteoclast-mediated osteolysis. Triptolide (PG490) is an active compound of the medicinal herb Tripterygium wilfordii Hook F (TWHF) or Lei Gong Teng with known anti-inflammatory properties. We found that triptolide inhibited osteoclastogenesis and bone resorption, as well as RANKL-induced NF-қB activities as monitored by luciferase reporter gene assays and the nuclear translocation of p65. In vivo studies showed that triptolide attenuates titanium-induced osteolysis and osteoclast formation in a mouse calvarial model. Considering that drugs which protect against localized bone loss are critically needed for the effective treatment of particle-induced osteolysis, our data suggest that triptolide might have therapeutic potential for the treatment of bone lytic diseases caused by prosthetic wear particles.

Identification of therapeutic target genes with DNA microarray in multiple myeloma cell line treated by IKKβ/NF-κB inhibitor

PURPOSE

To explore the mechanism of resistance to IKKβ inhibitor in multiple myeloma (MM) cells and uncover novel therapeutic targets for MM.

METHODS

We downloaded the microarray data (GSE8476) from GEO (Gene Expression Omnibus) database. The data were derived from the human MM cells lines (L363 cells) treated with IKKβ inhibitor MLN120b (MLN) for eight, 12 and 24 hours. Furthermore, we applied the Search Tool for the Retrieval of Interacting Genes (STRING) and Expression Analysis Systematic Explorer (EASE) database to construct protein-protein interaction networks and identified over-represented pathway among DEGs (differentially expressed genes).

RESULTS

We obtained 108 DGEs in 8h vs. 12h group and 101 ones in 8h vs. 24h group. Most of DGEs were found to be involved in biological regulation. The significant pathways were Ig A pathway and the CAMs pathways. In addition, 24 common DGEs were found in the networks of the two groups such as ICAM 3 and SELL.

CONCLUSION

Intercellular adhesion molecule 3 and SELL may be potential targets in multiple myeloma treatment in the future.

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.

Combined therapeutic effects of vinblastine and Astragalus saponins in human colon cancer cells and tumor xenograft via inhibition of tumor growth and proangiogenic factors

Our previous study had demonstrated that Astragalus saponins (AST) could reduce the side effects of orthodox chemotherapeutic drugs, while concurrently promote antitumor activity. In the present study, we attempted to investigate the potential synergistic anticarcinogenic effects of AST and a vinca alkaloid vinblastine (VBL). Reduced expression of key proangiogenic and metastatic factors including VEGF, bFGF, metalloproteinase (MMP)-2, and MMP-9 was detected in VBL-treated colon cancer cells, with further downregulation by combined VBL/AST treatment. Subsequently, VBL or AST decreased LoVo cell invasiveness, with further reduction when the drugs were cotreated. Significant growth inhibition and cell cycle arrest at G2/M phase were achieved by either drug treatment with apparent synergistic effects. VBL-induced apoptosis was confirmed but found to be unrelated to induction of the novel apoptotic protein NSAID-activated gene 1. In vivo study in tumor xenograft indicates that combined VBL/AST treatment resulted in sustained regression of tumor growth, with attenuation of the neutropenic and anemic effects of VBL. In addition, downregulation of proangiogenic and proliferative factors was also visualized, with boosting effect by combined drug treatment. These findings have provided evidence that AST combined with adjuvant chemotherapeutics like VBL could alleviate cancer development through diversified modes of action, including the regulation of angiogenesis.

Triptolide Synergistically Enhances Temozolomide-Induced Apoptosis and Potentiates Inhibition of NF-κB Signaling in Glioma Initiating Cells

Glioblastoma multiforme (GBM) is a lethal solid cancer in adults. Temozolomide (TMZ) is a first-line chemotherapeutic agent but the efficacy is limited by intrinsic and acquired resistance in GBM. Triptolide (TPL), a derivative from traditional Chinese medicine, demonstrated anti-tumor activity. In this study, we explored the interaction of TPL and TMZ in glioma-initiating cells (GICs) and the potential mechanism. A GIC line (GIC-1) was successfully established. Cell viability of GIC-1 after treatment was measured using a CCK-8 assay. The interaction between TPL and TMZ was calculated from Chou–Talalay equations and isobologram. Self-renewal was evaluated with tumor sphere formation assay. Apoptosis was assessed with flow cytometry and western blot. Luciferase assay was employed to measure NF-κB transcriptional activity. The expression of NF-κB downstream genes, NF-κB nuclear translocalization and phoshorylation of IκBα and p65 were evaluated using western blot. We found that GIC-1 cells were resistant to TMZ, with the expected IC50 of 705.7 μmol/L. Co-treatment with TPL yielded a more than three-fold dose reduction of TMZ. TPL significantly increased the percentage of apoptotic cells and suppressed the tumor sphere formation when combined with TMZ. Phosphorylation of IκBα and p65 coupled with NF-κB nuclear translocalization were notably inhibited after a combined treatment. Co-incubation synergistically repressed NF-κB transcriptional activity and downstream gene expression. TPL sensitizes GICs to TMZ by synergistically enhancing apoptosis, which is likely resulting from the augmented repression of NF-κB signaling. TPL is therefore a potential chemosensitizer in the treatment of GBM.

Triptolide improves early survival of mesenchymal stem cells transplanted into rat myocardium

OBJECTIVE

To investigate whether triptolide can prolong the survival of rat mesenchymal stem cells (MSCs) transfected with the mouse hyperpolarization-activated cyclic nucleotide-gated channel 4 (mHCN4) gene in the myocardium.

METHODS

Grafted cell survival was determined using a sex-mismatched cell transplantation model and analysis of Y chromosome-specific Sry gene expression from hearts harvested at different time points after cell transplantation. ELISA and RT-PCR were used to measure protein and mRNA levels, respectively, of nuclear factor (NF)-κB, IL-1β, IL-6 and TNF-α.

RESULTS

Donor cell numbers decreased over time. Pretreatment with triptolide improved graft survival both 24 (29.3 ± 0.9%) and 72 h (17.5 ± 1.2%) after transplantation of MSCs and resulted in a 2.5-fold increase in the total cell number 72 h after cell transplantation. The mRNA expression and protein content of NF-κB, IL-1β, IL-6 and TNF-α were significantly reduced in the triptolide-treated group compared with the control groups. In addition, triptolide downregulated Bax but upregulated Bcl-2 in the injected region.

CONCLUSIONS

Transient treatment with triptolide may significantly improve the early survival of MSCs in vivo. The mechanism underlying this effect involves attenuating the inflammatory response via inhibition of the NF-κB signaling pathway.

Triptolide induces apoptotic cell death of multiple myeloma cells via transcriptional repression of Mcl-1

Triptolide, a diterpenoid trioxide purified from the Chinese herb Tripterygium wilfordii Hook F, has been used as a natural medicine in China for hundreds of years. Several reports have demonstrated that triptolide inhibits the proliferation of cancer cells in vitro and reduces the growth of several types of tumors in vivo. To address the potential of triptolide as a novel therapeutic agent for patients with multiple myeloma, we investigated the effects of triptolide on the induction of apoptosis in human multiple myeloma cells in vitro. Triptolide rapidly induces apoptotic cell death in various myeloma cell lines. Triptolide-induced apoptosis in myeloma cells is associated with the loss of mitochondrial transmembrane potential (∆ψm), the release of cytochrome c and Smac/DIABLO from mitochondria into the cytosol, and the activation of caspase-3 and caspase-9. Furthermore, triptolide induces a rapid decline in the levels of Mcl-1 protein that correlates with caspase activation and induction of apoptosis. Inhibition of Mcl-1 synthesis by triptolide occurs at the level of mRNA transcription and is associated with an inhibition of phosphorylation of RNA polymerase II CTD. These results indicate that Mcl-1 is an important target for triptolide-induced apoptosis in myeloma cells that occurs via inhibition of Mcl-1 mRNA transcription coupled with rapid protein degradation through the ubiquitin-proteasome pathway.

An anti-leishmanial thiadiazine agent induces multiple myeloma cell apoptosis by suppressing the nuclear factor kappaB signalling pathway

Background:

Nuclear factor κB (NFκB) has a critical role in the pathophysiology of multiple myeloma. Targeting NFκB is an important strategy for anti-myeloma drug discovery.

Methods:

Luciferase assay was used to evaluate the effects of DETT on NFκB activity. Annexin V–PI double staining and immunoblotting were used to evaluate DETT-induced cell apoptosis and suppression of NFκB signalling. Anti-myeloma activity was studied in nude mice.

Results:

DETT downregulated IKKα, β, p65, and p50 expression and inhibited phosphorylation of p65 (Ser536) and IκBα. Simultaneously, DETT increased IκBα, an inhibitor of the p65/p50 heterodimer, even in the presence of stimulants lipopolysaccharide, tumour necrosis factor-α, or interleukin-6. DETT inhibited NFκB transcription activity and downregulated NFκB-targeted genes, including Bcl-2, Bcl-XL, and XIAP as measured by their protein expression. Deregulation of NFκB signalling by DETT resulted in MM cell apoptosis characterised by cleavage of caspase-3, caspase-8, and PARP. Notably, this apoptosis was partly blocked by the activation of NFκB signalling in the presence of TNFα and IL-6. Moreover, DETT delayed myeloma tumour growth in nude mice without overt toxicity.

Conclusion:

DETT displays a promising potential for MM therapy as an inhibitor of the NFκB signalling pathway.

Triptolide-mediated inhibition of interferon signaling enhances vesicular stomatitis virus-based oncolysis

Preclinical and clinical trials demonstrated that use of oncolytic viruses (OVs) is a promising new therapeutic approach to treat multiple types of cancer. To further improve their viral oncolysis, experimental strategies are now combining OVs with different cytotoxic compounds. In this study, we investigated the capacity of triptolide - a natural anticancer molecule - to enhance vesicular stomatitis virus (VSV) oncolysis in OV-resistant cancer cells. Triptolide treatment increased VSV replication in the human prostate cancer cell line PC3 and in other VSV-resistant cells in a dose- and time-dependent manner in vitro and in vivo. Mechanistically, triptolide (TPL) inhibited the innate antiviral response by blocking type I interferon (IFN) signaling, downstream of IRF3 activation. Furthermore, triptolide-enhanced VSV-induced apoptosis in a dose-dependent fashion in VSV-resistant cells, as measured by annexin-V, cleaved caspase-3, and B-cell lymphoma 2 staining. In vivo, using the TSA mammary adenocarcinoma and PC3 mouse xenograft models, combination treatment with VSV and triptolide delayed tumor growth and prolonged survival of tumor-bearing animals by enhancing viral replication. Together, these results demonstrate that triptolide inhibition of IFN production sensitizes prostate cancer cells to VSV replication and virus-mediated apoptosis.

Triptolide induces apoptosis of PMA-treated THP-1 cells through activation of caspases, inhibition of NF-κB and activation of MAPKs

Triptolide is known to be involved in many cellular events, such as those related to immunosuppressive and antitumor activity. We investigated whether triptolide mediates these effects through multiple mechanisms, including activation of cell cycle arrest and caspase-dependent pathways, as well as by blocking nuclear factor-κB (NF-κB) activation and by potentiating the activities of the mitogen-activated protein kinase (MAPK) pathway, in phorbol myristate acetate (PMA)-differentiated THP-1 cells. Triptolide significantly inhibited cell proliferation in a dose- and time-dependent manner and it increased the apoptotic fraction in the cell cycle and the number of apoptotic THP-1 cells. Exposure of the cells to triptolide also increased caspase-3 activity in these cells. Furthermore, co-treatment of cells with triptolide and the pan-caspase inhibitor, Z-VAD-FMK, or the caspase-3 inhibitor, Z-DEVE-FMK, increased THP-1 cell growth. Triptolide treatment resulted in a significant decrease in mRNA expression levels in genes encoding Bcl-2, cyclin D1, p27 and survivin and an increase in those encoding Bax and p21 in THP-1 cells. Triptolide not only inhibited NF-κB activation, but also activated p38 MAPK and MEK/ERK phosphorylation. These results show that triptolide inhibits the growth of THP-1 cells by inducing apoptosis through caspase activation and the mechanism involves NF-κB inhibition and the MAPK pathway.

Triptolide inhibits MDM2 and induces apoptosis in acute lymphoblastic leukemia cells through a p53-independent pathway

Triptolide, a natural product derived from the Chinese plant Tripterygium wilfordii, is reported to exhibit antitumor effects in a broad range of cancers. The antitumor activity of triptolide is associated with its biologic activities, as it inhibits various proproliferative or antiapoptotic factors that are dominantly expressed in given types of cancer cells. Herein, we show that triptolide induced apoptosis in a subgroup of acute lymphoblastic leukemia (ALL) cells overexpressing the MDM2 oncoprotein by inhibiting MDM2 expression. More specifically, we found that triptolide inhibited MDM2 at the transcriptional level by suppressing its mRNA synthesis. This MDM2 inhibition led in turn to increased levels of p53 protein; however, p53 functionality was not activated due to the fact that triptolide-treated cells lacked induction of p21 and PUMA as well as in G(1) cell-cycle arrest. Triptolide-mediated downregulation of MDM2 increased inhibition of X-linked inhibitor of apoptosis protein (XIAP), its translational target, in a manner distinct from reactions to cellular stress and DNA-damaging agent ionizing radiation that induce XIAP due to p53-activated MDM2. These results suggest that increased inhibition of XIAP due to downregulation of MDM2 may play a critical role in triptolide-induced apoptosis in MDM2-overexpressing cancers.

Antifibrotic effects of triptolide on hepatic stellate cells and dimethylnitrosamine-intoxicated rats

Triptolide (C₃₈H₄₂O₆N₂, TP, a diterpene triepoxide derived from Tripterygium wilfordii Hook F.), is a potent immunosuppresive and antiinflammatory agent. The present study investigated whether TP exerted antihepatofibrotic effects in vitro and in vivo. A cell line of rat hepatic stellate cells (HSC-T6) was stimulated with tumor necrosis factor-α (TNF-α) or transforming growth factor (TGF)-β1. The inhibitory effects of TP on the nuclear factor-κB (NFκB) signaling cascade and fibrosis markers, including α-smooth muscle actin (α-SMA) and collagen, were assessed. An in vivo therapeutic study was conducted in dimethylnitrosamine (DMN)-treated rats. The rats were randomly assigned to one of three groups: control rats, DMN rats receiving vehicle only and DMN rats receiving TP (20 μg/kg). Treatment was given by gavage twice daily for 3 weeks starting 1 week after the start of DMN administration. TP (5-100 nM) concentration-dependently inhibited the NFκB transcriptional activity induced by TNF-α, lipopolysaccharide and phorbol 12-myristate 13-acetate in HSC-T6 cells. In addition, TP also suppressed TNF-α and TGF-β1-induced collagen deposition and α-SMA secretion in HSC-T6 cells. In vivo, TP treatment significantly reduced hepatic fibrosis scores, collagen contents, IL-6 and TNF-α levels, and the number of α-SMA and NFκB-positive cells in DMN rats. The results showed that TP exerted antifibrotic effects in both HSC-T6 cells and DMN rats.

Identification of in vivo and in vitro metabolites of triptolide by liquid chromatography-tandem mass spectrometry

Triptolide, a major active constituent of Tripterygium wilfordii Hook F, has multiple pharmacological activities. In this work, a rapid, sensitive and specific liquid chromatography coupled to an ion trap mass spectrometer (MS) with electrospray ionization (ESI) interface has been developed for identification of triptolide and some of its metabolites in rat urine after oral administration of a single dose (0.6 mg/kg) of triptolide to healthy rats, as well as some metabolites in vitro after incubation with rat liver microsome (RLM) and rat intestinal flora, respectively. All samples were separated on a reversed-phase C18 column using a mobile phase of acetonitrile/water (70:30, v/v) and detected by an on-line MS(n) detector. Identification and structural elucidation of the selected metabolites were performed by comparing their full scan MS(n) spectra with those of the parent drug. In this paper we identified ten metabolites in rat urine, four metabolites in RLM incubation solution and one metabolite in rat intestinal flora incubation solution, after drug administration. The metabolic reactions of triptolide that we observed in vivo were hydrolysis reaction, hydroxylation reaction, and the conjugate reaction with sulfate, glucuronide and GSH, respectively. The in vitro metabolic reactions of triptolide observed were hydrolysis and hydroxylation reactions.

Triptolide inhibits colon-rectal cancer cells proliferation by induction of G1 phase arrest through upregulation of p21

Triptolide, a diterpene triepoxide compound extracted from the traditional Chinese medicine herb Tripterygium wilfordii Hook F., is a potential cancer chemotherapeutic for tumors. However, the mechanism of anti-proliferative mechanism of triptolide in colon cancer cells is not entirely clear. Triptolide markedly inhibited HT29 and SW480 cells proliferation in a dose- and time-dependent manner. Triptolide decreased ERK and AKT phosphorylation, and GABPα expression in colon cancer cells. Beta-catenin expression and phosphorylation were not altered by incubation of triptolide. However, we found that triptolide repressed expression of LEF/TCF. Although it did not significantly affect cells apoptosis, triptolide induced G1 phase arrest dose-dependently. Further detection for the expression of cell cycle-related proteins suggesting that triptolide stimulate expression of p21 and repress cyclin A1. Increased p21 binded to CDK4/CDK6, therefore blocked function of CDK4/CDK6, and subsequently contribute to the G1 arrest. These data suggested that triptolide is a potential agent for treatment of colon cancer, and its anti-proliferation effect mainly occur through G1 phase arrest.

Triptolide enhances the sensitivity of multiple myeloma cells to dexamethasone via microRNAs

Recently triptolide (TPL) has been proved to have the capacity to inhibit the proliferation of multiple myeloma (MM) cells as well as leukemic cells in vitro. In the present study, we found a synergistic effect when TPL was added to dexamethasone to induce apoptosis in MM.1S cells. This combination induced a significantly higher proportion of apoptotic cells compared with those treated with each drug separately. TPL down-regulated the expression of miR142 - 5p and miR181a, which have been shown to inhibit glucocorticoid receptor (GR) expression. MicroRNA mimics and inhibitors inhibited or enhanced the synergistic effect between TPL and dexamethasone in inducing apoptosis in MM.1S cells, suggesting an important role of miR142 - 5p and miR181a in GR regulation by TPL. The in vitro proapoptotic effect of TPL associated with dexamethasone reveals a new lead for further clinical investigation into the treatment of patients with MM with TPL.

Triptolide induces cell-cycle arrest and apoptosis of human multiple myeloma cells in vitro via altering expression of histone demethylase LSD1 and JMJD2B

AIM

To elucidate the relationship between triptolide-induced changes in histone methylation and its antitumor effect on human multiple myeloma (MM) cells in vitro.

METHODS

Human multiple myeloma cell line RPMI8226 was used. Apoptosis was evaluated using Annexin-V-FITC/PI-labeled flow cytometry, Hoechst 33258 staining, and transmission electron microscopy. Flow cytometry was used to detect the cell cycle distribution of the apoptotic cells. The presence of the LSD1, JMJD2B, H3K4me2, H3K9me2, and H3K36me2 proteins was verified by Western blot analysis. Semi-quantitative real-time PCR was performed to examine the expression of LSD1 and JMJD2B.

RESULTS

Triptolide (10-160 nmol/L) suppressed the proliferation of MM cells in a dose- and time-dependent manner with an IC(50) value of 99.2 ± 9.0 nmol/L at 24 h. Triptolide (50 nmol/L) induced G(0)/G(1) cell cycle arrest in MM cells. The agent (50-150 nmol/L) induced apoptosis of MM cells in a dose-dependent manner. The same concentrations of triptolide suppressed the expression of dimethylated H3K4, dimethylated H3K9 and dimethylated H3K36 by altering the expression of histone demethylase LSD1 and JMJD2B without affecting the expression of histone demethylase LSD1.

CONCLUSION

Triptolide potently inhibits the growth of MM cells via regulating the expression of histone demethylase LSD1 and JMJD2B, which lead to abnormal histone methylation.

Monitoring a nuclear factor-κB signature of drug resistance in multiple myeloma

The emergence of acquired drug resistance results from multiple compensatory mechanisms acting to prevent cell death. Simultaneous monitoring of proteins involved in drug resistance is a major challenge for both elucidation of the underlying biology and development of candidate biomarkers for assessment of personalized cancer therapy. Here, we have utilized an integrated analytical platform based on SDS-PAGE protein fractionation prior to liquid chromatography coupled to multiple reaction monitoring mass spectrometry, a versatile and powerful tool for targeted quantification of proteins in complex matrices, to evaluate a well-characterized model system of melphalan resistance in multiple myeloma (MM). Quantitative assays were developed to measure protein expression related to signaling events and biological processes relevant to melphalan resistance in multiple myeloma, specifically: nuclear factor-κB subunits, members of the Bcl-2 family of apoptosis-regulating proteins, and Fanconi Anemia DNA repair components. SDS-PAGE protein fractionation prior to liquid chromatography coupled to multiple reaction monitoring methods were developed for quantification of these selected target proteins in amounts of material compatible with direct translation to clinical specimens (i.e. less than 50,000 cells). As proof of principle, both relative and absolute quantification were performed on cell line models of MM to compare protein expression before and after drug treatment in naïve cells and in drug resistant cells; these liquid chromatography-multiple reaction monitoring results are compared with existing literature and Western blots. The initial stage of a systems biology platform for examining drug resistance in MM has been implemented in cell line models and has been translated to MM cells isolated from a patient. The ultimate application of this platform could assist in clinical decision-making for individualized patient treatment. Although these specific assays have been developed to monitor MM, these techniques are expected to have broad applicability in cancer and other types of disease.

The main anticancer bullets of the Chinese medicinal herb, thunder god vine

The thunder god vine or Tripterygium wilfordii Hook. F. is a representative Chinese medicinal herb which has been used widely and successfully for centuries in treating inflammatory diseases. More than 100 components have been isolated from this plant, and most of them have potent therapeutic efficacy for a variety of autoimmune and inflammatory diseases. In the past four decades, the anticancer activities of the extracts from this medicinal herb have attracted intensive attention by researchers worldwide. The diterpenoid epoxide triptolide and the quinone triterpene celastrol are two important bioactive ingredients that show a divergent therapeutic profile and can perturb multiple signal pathways. Both compounds promise to turn traditional medicines into modern drugs. In this review, we will mainly address the anticancer activities and mechanisms of action of these two agents and briefly describe some other antitumor components of the thunder god vine.

In vitro synergistic cytotoxic effect of triptolide combined with hydroxycamptothecin on pancreatic cancer cells

Pancreatic cancer is a devastating disease characterized by low sensitivity to conventional chemotherapeutic treatment that has a poor prognosis. Therefore, novel effective chemotherapeutic regimens need to be developed. In this study, we analyzed the combined cytotoxic effect of triptolide and hydroxycamptothecin (HCPT) on pancreatic cancer cell line PANC-1 by using 3-(4.5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) and fluorescence- activated cell sorting (FACS) assays. Our results showed that the sensitivity of a combined therapy using triptolide and HCPT was higher than that of triptolide or HCPT alone and that activation of caspase-9/caspase-3 and inhibition of nuclear factor-kappaB (NF-κB) signaling pathway may contribute to the synergistic cytotoxic effect of this combination therapy. Therefore, our observations provided evidence supporting the clinical applications of the combination chemotherapy using triptolide and HCPT for treating pancreatic cancer.

Triptolide inhibits the proliferation of cells from lymphocytic leukemic cell lines in association with downregulation of NF-κB activity and miR-16-1*

AIM

To examine the effects of triptolide (TPL) on T-cell leukemia cells and identify their underlying mechanisms.

METHODS

The cytotoxicity of TPL was assessed by MTT assay. Cell apoptosis was determined using annexin V and DAPI staining and analyzed by flow cytometry or fluorescence microscopy. The activation of caspase pathways and the expression of nuclear factor κB (NF-κB) p65 were examined by Western blotting. Differences in microRNA (miRNA) expression in Molt-4 and Jurkat cells before and after TPL treatment were identified using microarrays and real-time RT-PCR, respectively.

RESULTS

TPL 20-160 nmol/L treatment potently inhibited cell growth and induced apoptosis in T-cell lymphocytic leukemia cell lines. Molt-4 and Jurkat cells, however, were more sensitive to TPL than L428 and Raji cells. After 24 h of treatment, bortezomib abrogated the growth of Molt-4 and Jurkat cells with an IC(50) of 15.25 and 24.68 nmol/L, respectively. Using Molt-4 cells, we demonstrated that treatment 20-80 nmol/L inhibited the translocation of NF-κB p65 from the cytoplasm to the nucleus and that phosphorylated NF-κB p65 in nuclear extracts was down-regulated in a dose-dependent manner. Similar results were also seen in Jurkat cells but not in L428 cells, as these cells are resistant to TPL and bortezomib (a NF-κB inhibitor). Twenty-three miRNAs were differentially expressed after TPL treatment. Functional analysis revealed that TPL treatment could inhibit expression of miR-16-1* and that transfection of miR-16-1* led to significantly decreased apoptosis induced by TPL.

CONCLUSION

Our in vitro studies suggest that TPL might be an effective therapeutic agent for treatment of T-cell lymphocytic leukemia and that its cytotoxic effects could be associated with inhibition of NF-κB and down-regulation of miR-16-1*.

Triptolide downregulates human GD3 synthase (hST8Sia I) gene expression in SK-MEL-2 human melanoma cells

In this study, we have shown that gene expression of human GD3 synthase (hST8Sia I) is suppressed by triptolide (TPL) in human melanoma SK-MEL-2 cells. To elucidate the mechanism underlying the downregulation of hST8Sia I gene expression in TPL-treated SK-MEL-2 cells, we characterized the TPL-inducible promoter region within the hST8Sia I gene using luciferase constructs carrying 5'-deletions of the hST8Sia I promoter. Functional analysis of the 5'-flanking region of the hST8Sia I gene demonstrated that the -1146 to -646 region, which contains putative binding sites for transcription factors c-Ets-1, CREB, AP-1 and NF-κB, functions as the TPL-inducible promoter of hST8Sia I in SK-MEL-2 cells. Site-directed mutagenesis and ChIP analysis indicated that the NF-κB binding site at -731 to -722 is crucial for TPL-induced suppression of hST8Sia I in SK-MEL-2 cells. This suggests that TPL induces down-regulation of hST8Sia I gene expression through NF-κB activation in human melanoma cells.

Triptolide and its expanding multiple pharmacological functions

Triptolide, a diterpene triepoxide, is a major active component of extracts derived from the medicinal plant Tripterygium wilfordii Hook F (TWHF). Triptolide has multiple pharmacological activities including anti-inflammatory, immune modulation, antiproliferative and proapoptotic activity. So, triptolide has been widely used to treat inflammatory diseases, autoimmune diseases, organ transplantation and even tumors. Triptolide cannot only induce tumor cell apoptosis directly, but can also enhance apoptosis induced by cytotoxic agents such as TNF-α, TRAIL and chemotherapeutic agents regardless of p53 phenotype by inhibiting NFκB activation. Recently, the cellular targets of triptolide, such as MKP-1, HSP, 5-Lox, RNA polymerase and histone methyl-transferases had been demonstrated. However, the clinical use of triptolide is often limited by its severe toxicity and water-insolubility. New water-soluble triptolide derivatives have been designed and synthesized, such as PG490-88 or F60008, which have been shown to be safe and potent antitumor agent. Importantly, PG490-88 has been approved entry into Phase I clinical trial for treatment of prostate cancer in USA. This review will focus on these breakthrough findings of triptolide and its implications.