Triptolide-Assisted Phosphorylation of p53 Suppresses Inflammation-Induced NF-κB Survival Pathways in Cancer Cells

Antitumor mechanisms and future clinical applications of the natural product triptolide

Triptolide (TPL) is a compound sourced from Tripterygium wilfordii Hook. F., a traditional Chinese medicinal herb recognized for its impressive anti-inflammatory, anti-angiogenic, immunosuppressive, and antitumor qualities. Notwithstanding its favorable attributes, the precise mechanism through which TPL influences tumor cells remains enigmatic. Its toxicity and limited water solubility significantly impede the clinical application of TPL. We offer a comprehensive overview of recent research endeavors aimed at unraveling the antitumor mechanism of TPL in this review. Additionally, we briefly discuss current strategies to effectively manage the challenges associated with TPL in future clinical applications. By compiling this information, we aim to enhance the understanding of the underlying mechanisms involved in TPL and identify potential avenues for further advancement in antitumor therapy.

Isoforskolin modulates AQP4-SPP1-PIK3C3 related pathway for chronic obstructive pulmonary disease via cAMP signaling

BACKGROUND

Cyclic adenosine monophosphate (cAMP) levels are directly activated by adenylate cyclase (AC) and play an anti-inflammatory role in chronic obstructive pulmonary disease (COPD). Previously, we have shown that isoforskolin (ISOF) can effectively activate AC1 and AC2 in vitro, improve pulmonary ventilation and reduce the inflammatory response in COPD model rats, supporting that ISOF may be a potential drug for the prevention and treatment of COPD, but the mechanism has not been explored in detail.

METHODS

The potential pharmacological mechanisms of ISOF against COPD were analyzed by network pharmacology and multi-omics based on pharmacodynamic study. To use specific agonists, inhibitors and/or SiRNA for gene regulation function studies, combined qPCR, WB were applied to detect changes in mRNA and protein expression of important targets PIK3C3, AKT, mTOR, SPP1 and AQP4 which related to ISOF effect on COPD. And the key inflammatory factors detected by ELISA.

RESULTS

Bioinformatics suggested that the anti-COPD pharmacological mechanism of ISOF was related to PI3K-AKT signaling pathway, and suggested target protein like PIK3C3, AQP4, SPP1, AKT, mTOR. Using the AQP4 inhibitor,or inhibiting SPP1 expression by siRNA-SPP1 could block the PIK3C3-AKT-mTOR pathway and ameliorate chronic inflammation. ISOF showed cAMP-promoting effect then suppressed AQP4 expression, together with decreased level of IL-1β, IL-6, and IL-8.

CONCLUSIONS

These findings demonstrate ISOF controlled the cAMP-regulated PIK3C3-AKT-mTOR pathway, thereby alleviating inflammatory development in COPD. The cAMP/AQP4/PIK3C3 axis also modulate Th17/Treg differentiation, revealed potential therapeutic targets for this disease.

An overview of Twist1 in glioma progression and recurrence

Glioma cells are characterized by high migration ability, resulting in the aggressive growth of the tumors and poor prognosis of patients. Epithelial-to-mesenchymal transition (EMT) is one of the most important steps for tumor migration and metastasis and be elevated during glioma progression and recurrence. Twist1 is a basic helix-loop-helix transcription factor and a key transcription factor involved in the process of EMT. Twist1 is related to glioma mesenchymal change, invasion, heterogeneity, self-renewal of tumor stem cells, angiogenesis, etc., and may be used as a prognostic indicator and therapeutic target for glioma patients. This paper mainly reviews the structural characteristics, regulatory mechanisms, and apparent regulation of Twist1, as well as the roles of Twist1 during glioma progression and recurrence, providing new revelations for its use as a potential drug target and glioma treatment research.

A Bibliometric Analysis of Triptolide and the Recent Advances in Treating Non-Small Cell Lung Cancer

In recent decades, natural products derived from plants and their derivatives have attracted great interest in the field of disease treatment. Triptolide is a tricyclic diterpene extracted from Tripterygium wilfordii, a traditional Chinese medicine, which has shown excellent therapeutic potential in the fields of immune inflammation and cancer treatment. In this study, 1,106 Web-of-Science-indexed manuscripts and 1,160 Chinese-National-Knowledge-Infrastructure-indexed manuscripts regarding triptolide published between 2011 and 2021 were analyzed, mapping the co-occurrence networks of keywords and clusters using CiteSpace software. The research frontier and development trend were determined by keyword frequency and cluster analysis, which can be used to predict the future research development of triptolide. Non-small cell lung cancer (NSCLC) is most common in lung cancer patients, accounting for about 80% of all lung cancer patients. New evidence suggests that triptolide effectively inhibits the development and metastasis of NSCLC by the induction of apoptosis, reversion of EMT, and regulation of gene expression. Specifically, it acts on NF-κB, MAPKs, P53, Wnt/β-catenin, and microRNAs (miRNAs), signaling pathways and molecular mechanisms. Consequently, this article reviews the research progress of the anti-NSCLC effect of triptolide. In addition, attenuated studies on triptolide and the potential of tumor immunotherapy are also discussed.

Modulation of TLR/NF-κB/NLRP Signaling by Bioactive Phytocompounds: A Promising Strategy to Augment Cancer Chemotherapy and Immunotherapy

Background

Tumors often progress to a more aggressive phenotype to resist drugs. Multiple dysregulated pathways are behind this tumor behavior which is known as cancer chemoresistance. Thus, there is an emerging need to discover pivotal signaling pathways involved in the resistance to chemotherapeutic agents and cancer immunotherapy. Reports indicate the critical role of the toll-like receptor (TLR)/nuclear factor-κB (NF-κB)/Nod-like receptor pyrin domain-containing (NLRP) pathway in cancer initiation, progression, and development. Therefore, targeting TLR/NF-κB/NLRP signaling is a promising strategy to augment cancer chemotherapy and immunotherapy and to combat chemoresistance. Considering the potential of phytochemicals in the regulation of multiple dysregulated pathways during cancer initiation, promotion, and progression, such compounds could be suitable candidates against cancer chemoresistance.

Objectives

This is the first comprehensive and systematic review regarding the role of phytochemicals in the mitigation of chemoresistance by regulating the TLR/NF-κB/NLRP signaling pathway in chemotherapy and immunotherapy.

Methods

A comprehensive and systematic review was designed based on Web of Science, PubMed, Scopus, and Cochrane electronic databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to include papers on TLR/NF-κB/NLRP and chemotherapy/immunotherapy/chemoresistance by phytochemicals.

Results

Phytochemicals are promising multi-targeting candidates against the TLR/NF-κB/NLRP signaling pathway and interconnected mediators. Employing phenolic compounds, alkaloids, terpenoids, and sulfur compounds could be a promising strategy for managing cancer chemoresistance through the modulation of the TLR/NF-κB/NLRP signaling pathway. Novel delivery systems of phytochemicals in cancer chemotherapy/immunotherapy are also highlighted.

Conclusion

Targeting TLR/NF-κB/NLRP signaling with bioactive phytocompounds reverses chemoresistance and improves the outcome for chemotherapy and immunotherapy in both preclinical and clinical stages.

Triptolide: pharmacological spectrum, biosynthesis, chemical synthesis and derivatives

Triptolide, an abietane-type diterpenoid isolated from Tripterygium wilfordii Hook. F., has significant pharmacological activity. Research results show that triptolide has obvious inhibitory effects on many solid tumors. Therefore, triptolide has become one of the lead compounds candidates for being the next "blockbuster" drug, and multiple triptolide derivatives have entered clinical research. An increasing number of researchers have developed triptolide synthesis methods to meet the clinical need. To provide new ideas for researchers in different disciplines and connect different disciplines with researchers aiming to solve scientific problems more efficiently, this article reviews the research progress made with analyzes of triptolide pharmacological activity, biosynthetic pathways, and chemical synthesis pathways and reported in toxicological and clinical studies of derivatives over the past 20 years, which have laid the foundation for subsequent researchers to study triptolide in many ways.

Perspectives and controversies regarding the use of natural products for the treatment of lung cancer

Lung cancer is the leading cause of cancer‐related mortality both in men and women and accounts for 18.4% of all cancer‐related deaths. Although advanced therapy methods have been developed, the prognosis of lung cancer patients remains extremely poor. Over the past few decades, clinicians and researchers have found that chemical compounds extracted from natural products may be useful for treating lung cancer. Drug formulations derived from natural compounds, such as paclitaxel, doxorubicin, and camptothecin, have been successfully used as chemotherapeutics for lung cancer. In recent years, hundreds of new natural compounds that can be used to treat lung cancer have been found through basic and sub‐clinical research. However, there has not been a corresponding increase in the number of drugs that have been used in a clinical setting. The probable reasons may include low solubility, limited absorption, unfavorable metabolism, and severe side effects. In this review, we present a summary of the natural compounds that have been proven to be effective for the treatment of lung cancer, as well as an understanding of the mechanisms underlying their pharmacological effects. We have also highlighted current controversies and have attempted to provide solutions for the clinical translation of these compounds.

Triptolide reduces salivary gland damage in a non-obese diabetic mice model of Sjögren's syndrome via JAK/STAT and NF-κB signaling pathways

Triptolide (TP) has anti-inflammatory and immunosuppressive effects. However, the effect of triptolide on Sjögren's syndrome (SS) is rarely reported. In this paper, we studied the effects of triptolide on non-obese diabetes mice model of SS. In this study, salivary flow rate was measured every two weeks, and autoantibodies levels in the serum were detected. Salivary gland index and spleen index were detected, pathological changes of salivary gland were detected by hematoxylin-eosin staining, inflammatory factors were detected by enzyme linked immunosorbent assay, lymphocytes were detected by flow cytometry, proliferation of T cells and B cells were detected, and related proteins were detected by Western blot. Triptolide increased salivary flow rate and salivary gland index, and decreased spleen gland index. Moreover, triptolide reduced the infiltration of lymphocytes to salivary glands, decreased the level of autoantibodies in serum, and reduced the inflammatory factors in salivary glands and IFN-γ induced salivary gland epithelial cells. Further, triptolide inhibited activator of JAK/STAT pathway and NF-κB pathway. In conclusion, triptolide could inhibit the infiltration of lymphocytes and the expression of inflammatory factors through JAK/STAT pathway and NF-κB pathway. Thus, triptolide may be used as a potential drug to treat SS.

Targeting the tumor immune microenvironment with "nutraceuticals": From bench to clinical trials

The occurrence of immune effector cells in the tissue microenvironment during neoplastic progression is critical in determining tumor growth outcomes. On the other hand, tumors may also avoid immune system-mediated elimination by recruiting immunosuppressive leukocytes and soluble factors, which coordinate a tumor microenvironment that counteracts the efficiency of the antitumor immune response. Checkpoint inhibitor therapy results have indicated a way forward via activation of the immune system against cancer. Widespread evidence has shown that different compounds in foods, when administered as purified substances, can act as immunomodulators in humans and animals. Although there is no universally accepted definition of nutraceuticals, the term identifies a wide category of natural compounds that may impact health and disease statuses and includes purified substances from natural sources, plant extracts, dietary supplements, vitamins, phytonutrients, and various products with combinations of functional ingredients. In this review, we summarize the current knowledge on the immunomodulatory effects of nutraceuticals with a special focus on the cancer microenvironment, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of nutraceuticals for envisioning future therapies employing nutraceuticals as chemoadjuvants.

Cetuximab-Triptolide Conjugate Suppresses the Growth of EGFR-Overexpressing Lung Cancers through Targeting RNA Polymerase II

To overcome poor pharmacokinetics and toxicity of triptolide (TPL), a natural compound that exhibits potent anticancer activities, we developed a novel antibody-drug conjugate (ADC) to specifically deliver TPL to epidermal growth factor receptor (EGFR)-overexpressing non-small cell lung cancer (NSCLC) and others. The ADC (Cet-TPL) is made by conjugation of TPL to lysine residues of cetuximab (Cet), a clinically available anti-EGFR monoclonal antibody. Studies of antitumor efficacy demonstrated that Cet-TPL drastically suppressed in vitro proliferation and in vivo growth of these EGFR-overexpressing cancers, including NSCLC A549 and H1299 cells and two patient-derived xenografts, and head and neck squamous carcinoma UM-SCC6 cell, while it did not inhibit the proliferation and growth of NSCLC H520 that rarely expresses EGFR. Furthermore, immunofluorescence analysis revealed that Cet-TPL was effectively internalized and transported into lysosomes of EGFR-overexpressing cells. Cet-TPL effectively led to degradation of RNA polymerase II (Pol II) and demethylation of histone H3 lysines, and significantly induced apoptosis in these EGFR-overexpressing cancers. Compared with TPL, Cet, or their combination, Cet-TPL displayed higher target-specific cytotoxicity against EGFR-expressing cancers and much lower in vivo toxicity. In addition, Cet-TPL efficiently suppressed the activated EGFR pathway in UM-SCC6 cancer cells. Taken together, Cet-TPL represents a potent targeting therapeutic agent against EGFR-overexpressing NSCLC and others.

Triptolide alleviates radiation-induced pulmonary fibrosis via inhibiting IKKβ stimulated LOX production

Lysyl oxidase (LOX) is involved in fibrosis by catalyzing collagen cross-linking. Previous work observed that Triptolide (TPL) alleviated radiation-induced pulmonary fibrosis (RIPF), but it is unknown whether the anti-RIPF effect of TPL is related to LOX. In a mouse model of RIPF, we found that LOX persistently increased in RIPF which was significantly lowered by TPL. Excessive LOX aggravated fibrotic lesions in RIPF, while LOX inhibition mitigated RIPF. Irradiation enhanced the transcription and synthesis of LOX by lung fibroblasts through IKKβ/NFκB activation, and siRNA knockdown IKKβ largely abolished LOX production. By interfering radiation induced IKKβ activation, TPL prevented NFκB nuclear translocation and DNA binding, and potently decreased LOX synthesis. Our results demonstrate that the anti-RIPF effect of TPL is associated with reduction of LOX production which mediated by inhibition of IKKβ/NFκB pathway.

Impact of triptolide during ex vivo lung perfusion on grafts after transplantation in a rat model

OBJECTIVE

Ex vivo lung perfusion creates a proinflammatory environment leading to deterioration in graft quality that may contribute to post-transplant graft dysfunction. Triptolide has been shown to have a therapeutic potential in various disease states because of its anti-inflammatory properties. On this basis, we investigated the impact of triptolide on graft preservation during ex vivo lung perfusion and associated post-transplant outcomes in a rat transplant model.

METHODS

We performed rat normothermic ex vivo lung perfusion with acellular Steen solution containing 100 nM triptolide for 4 hours and compared the data with untreated lungs. Orthotopic single lung transplantation after ex vivo lung perfusion was performed.

RESULTS

Physiologic and functional parameters of lung grafts on ex vivo lung perfusion with triptolide were better than those without treatment. Graft glucose consumption was significantly attenuated on ex vivo lung perfusion with triptolide via inhibition of hypoxia signaling resulting in improved mitochondrial function and reduced oxidative stress. Also, intragraft inflammation was markedly lower in triptolide-treated lungs because of inhibition of nuclear factor-κB signaling. Furthermore, post-transplant graft function and inflammatory events were significantly improved in the triptolide group compared with the untreated group.

CONCLUSIONS

Treatment of lung grafts with triptolide during ex vivo lung perfusion may serve to enhance graft preservation and improve graft protection resulting in better post-transplant outcomes.

The Roles of Plant-Derived Triptolide on Non-Small Cell Lung Cancer

Over the past decade, natural compounds have been proven to be effective against many human diseases, including cancers. Triptolide (TPL), a diterpenoid triepoxide from the Chinese herb Tripterygium wilfordii Hook F, has exhibited attractive cytotoxic activity on several cancer cells. An increasing number of studies have emphasized the antitumor effects of TPL on non-small cell lung cancer (NSCLC). Here we mainly focused on the key molecular signaling pathways that lead to the inhibitory effects of TPL on human NSCLC, such as mitogen-activated protein kinases (MAPKs) modulation, inhibition of NF-κB activation, suppression of miRNA expression, etc. In addition, the effect of TIG on immune response in cancer patients is summarized for improved immune modulation utilization. However, the clinical use of TPL is often limited by its severe toxicity and water insolubility. Future clinical trials and drug delivery strategies that will evaluate the security and validate the underlying tumor-killing properties of TPL in human NSCLC are also to be discussed.

Apoptotic Pathway as the Therapeutic Target for Anticancer Traditional Chinese Medicines

Cancer is a leading cause of morbidity and mortality worldwide. Apoptosis is a process of programmed cell death and it plays a vital role in human development and tissue homeostasis. Mounting evidence indicates that apoptosis is closely related to the survival of cancer and it has emerged as a key target for the discovery and development of novel anticancer drugs. Various studies indicate that targeting the apoptotic signaling pathway by anticancer drugs is an important mechanism in cancer therapy. Therefore, numerous novel anticancer agents have been discovered and developed from traditional Chinese medicines (TCMs) by targeting the cellular apoptotic pathway of cancer cells and shown clinically beneficial effects in cancer therapy. This review aims to provide a comprehensive discussion for the role, pharmacology, related biology, and possible mechanism(s) of a number of important anticancer TCMs and their derivatives mainly targeting the cellular apoptotic pathway. It may have important clinical implications in cancer therapy.

Inhibition of RNA polymerase III transcription by Triptolide attenuates colorectal tumorigenesis

Background

Upregulation of RNA polymerase (Pol) III products, including tRNAs and 5S rRNA, in tumor cells leads to enhanced protein synthesis and tumor formation, making it a potential target for cancer treatment. In this study, we evaluated the inhibition of Pol III transcription by triptolide and the anti-cancer effect of this drug in colorectal tumorigenesis.

Methods

The effect of triptolide on colorectal cancer development was assessed in colorectal cancer mouse models, 3D organoids, and cultured cells. Colorectal cancer cells were treated with triptolide. Pol III transcription was measured by real-time quantitative polymerase chain reaction (PCR). The formation of TFIIIB, a multi-subunit transcription factor for Pol III, was determined by chromatin immunoprecipitation (ChIP), co-immunoprecipitation (Co-IP), and fluorescence resonance energy transfer (FRET).

Results

Triptolide reduced both tumor number and tumor size in adenomatous polyposis coli (Apc) mutated (Apc^Min/+) mice as well as AOM/DSS-induced mice. Moreover, triptolide effectively inhibited colorectal cancer cell proliferation, colony formation, and organoid growth in vitro, which was associated with decreased Pol III target genes. Mechanistically, triptolide treatment blocked TBP/Brf1interaction, leading to the reduced formation of TFIIIB at the promoters of tRNAs and 5S rRNA.

Conclusions

Together, our data suggest that inhibition of Pol III transcription with existing drugs such as triptolide provides a new avenue for developing novel therapies for colorectal cancer.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1232-x) contains supplementary material, which is available to authorized users.

Triptolide Induces Glioma Cell Autophagy and Apoptosis via Upregulating the ROS/JNK and Downregulating the Akt/mTOR Signaling Pathways

Apoptosis and autophagy are the two prominent forms of developmental cell death, and researches have shown that crosstalk exists between these two processes. A prior study demonstrated that triptolide inhibited the proliferation of malignant glioma cells. However, whether apoptosis and autophagy participate in the inhibitory effect of triptolide in glioma cells has not been clarified. In the present study, we demonstrated that triptolide potently inhibited the growth of glioma cells by inducing cell cycle arrest at the G2/M phase. Additionally, the treatment with triptolide induced apoptosis and autophagy in various glioma cell lines. Triptolide-induced autophagy may have tumor-supporting effects. Autophagy and apoptosis could cross-inhibit each other in glioma cells treated with triptolide. Moreover, we found that triptolide induced ROS production and JNK activation and inhibited the activity of Akt and mTOR. Finally, we demonstrated that triptolide suppressed tumor growth in an orthotopic xenograft glioma model. Collectively, these data indicated that triptolide induced G2/M phase arrest, apoptosis, and autophagy via activating the ROS/JNK and blocking the Akt/mTOR signaling pathways in glioma cells. Triptolide may be a potential anti-tumor drug targeting gliomas.

Cathepsin B mediated scramblase activation triggers cytotoxicity and cell cycle arrest by andrographolide to overcome cellular resistance in cisplatin resistant human hepatocellular carcinoma HepG2 cells

Andrographolide regimen in single or in combination with anticancer drugs is a promising new strategy to reverse chemoresistance in heaptocellular carcinoma. Apoptosis inducing factor (AIF) may regulate a complementary, cooperative or redundant pathway, along with caspase cascades. Despite these findings, mechanisms underlying caspase-dependent and-independent signaling pathways in andrographolide -induced apoptosis in cisplatin-resistant human hepatocellular carcinoma cell line (HepG2CR) remain unclear. Andrographolide treatment effectively reduced NF-κβ nuclear localization by modulating protein kinase A- protein phosphatase 2 A- Iκβ kinase (PKA/PP2 A/IKK) axis that in turn maintains initiator caspase8 activity. Lysosomal distribution of tBid stimulates cytosolic cathepsin B resulting accumulation of truncated-AIF with induction in scramblase mediated phosphatidylserine exposure in HepG2CR cells. Andrographolide treatment thereby switch on subG1 phase arrest by modulating cellular check points (cyclin A, B, cyclin dependent kinase-1) cueing to the apoptosis event. Collectively, this study suggested antineoplastic potential of andrographolide through PKA/PP2 A/IKK pathway in HepG2CR cells.

Triptolide delays disease progression in an adult rat model of polycystic kidney disease through the JAK2-STAT3 pathway

The aim of our current study was to investigate the long-term effect and the mechanism of triptolide in an adult nonorthologous rat model of polycystic kidney disease (PKD). Male wild-type (+/+) and Cy/+ cystic Han:SPRD rats were treated with vehicle or triptolide from 4 to 16 wk of age. Rats were killed at 16 wk of age for blood, urine, and organ collection. Human-derived WT9–12 PKD cells were treated with triptolide with or without IL-6 pretreatment. Cell proliferation, apoptosis, and cytotoxicity were determined. Western blotting and immunohistochemistry analysis were performed to evaluate the activation of IL-6-JAK2-STAT3 pathway. Renal function was protected by 12 wk of triptolide treatment in cystic Han:SPRD rats as shown by reduced blood urea nitrogen, serum creatinine, and proteinuria levels. Cyst and kidney growth were also retarded by triptolide treatment in Cy/+ rats. We further found that the proliferation index was reduced by triptolide in cystic rats, which was correlated with the reduced expression of IL-6/IL-6 receptor, decreased phosphorylation of JAK2-STAT3, and increased expression of suppressor of cytokine signaling 3 (SOCS3). The inhibitory effect of triptolide was further studied in WT9–12 cells. Triptolide inhibited cell proliferation and the activation of JAK2-STAT3 pathway in PKD cells, but it increased the expression of SOCS3. Pretreatment with IL-6 attenuated the inhibitory effect of triptolide on STAT3 phosphorylation. Our study revealed a long-term beneficial effect of triptolide in PKD that was probably through inhibition of the JAK2-STAT3 pathway.

Targeting IκappaB kinases for cancer therapy

The inhibitory kappa B kinases (IKKs) and IKK related kinases are crucial regulators of the pro-inflammatory transcription factor, nuclear factor kappa B (NF-κB). The dysregulation in the activities of these kinases has been reported in several cancer types. These kinases are known to regulate survival, proliferation, invasion, angiogenesis, and metastasis of cancer cells. Thus, IKK and IKK related kinases have emerged as an attractive target for the development of cancer therapeutics. Several IKK inhibitors have been developed, few of which have advanced to the clinic. These inhibitors target IKK either directly or indirectly by modulating the activities of other signaling molecules. Some inhibitors suppress IKK activity by disrupting the protein-protein interaction in the IKK complex. The inhibition of IKK has also been shown to enhance the efficacy of conventional chemotherapeutic agents. Because IKK and NF-κB are the key components of innate immunity, suppressing IKK is associated with the risk of immune suppression. Furthermore, IKK inhibitors may hit other signaling molecules and thus may produce off-target effects. Recent studies suggest that multiple cytoplasmic and nuclear proteins distinct from NF-κB and inhibitory κB are also substrates of IKK. In this review, we discuss the utility of IKK inhibitors for cancer therapy. The limitations associated with the intervention of IKK are also discussed.

A Mechanistic Overview of Triptolide and Celastrol, Natural Products from Tripterygium wilfordii Hook F

Triptolide and celastrol are predominantly active natural products isolated from the medicinal plant Tripterygium wilfordii Hook F. These compounds exhibit similar pharmacological activities, including anti-cancer, anti-inflammation, anti-obesity, and anti-diabetic activities. Triptolide and celastrol also provide neuroprotection and prevent cardiovascular and metabolic diseases. However, toxicity restricts the further development of triptolide and celastrol. In this review, we comprehensively review therapeutic targets and mechanisms of action, and translational study of triptolide and celastrol. We systemically discuss the structure-activity-relationship of triptolide, celastrol, and their derivatives. Furthermore, we propose the use of structural derivatives, targeted therapy, and combination treatment as possible solutions to reduce toxicity and increase therapeutic window of these potent natural products from T. wilfordii Hook F.

P53 modulates hepatic insulin sensitivity through NF-κB and p38/ERK MAPK pathways

Besides its well-established oncosuppressor activity, the role of p53 in regulating metabolic pathways has been recently identified. Nevertheless, the function of p53 with respect to insulin resistance appears highly controversial. To address this issue, we investigated the expression of p53 in experimental model of insulin resistance. Then we used activator (nutlin-3α) and inhibitor (pifithrin-α, PFT-α) of p53 in HepG2 cell. Here we showed that p53 protein level was decreased in the hepatic tissue of high-fat diet-induced insulin resistance mice, genetically diabetic ob/ob mice and palmitate (PA) treated HepG2 cells. And high expression of phosphor-p38, ERK1/2 and nuclear factor kappa B (NF-κB) p65 accompanied with low expression of p53. But activation of p53 with nutlin-3α prevented PA-induced reduction of glucose consumption and suppression of insulin signaling pathways. At the same time, nutlin-3α downregulated the activation of NF-κB, p38 and ERK1/2 pathways upon stimulation with PA. In contrast, inhibition of p53 with PFT-α decreased glucose consumption and suppressed insulin signaling pathway. Furthermore, PFT-α activated NF-κB, p38 and ERK1/2 pathways in HepG2 cells. Overall, these results suggest that p53 is involved in improving insulin sensitivity of hepatic cells via inhibition of mitogen-activated protein kinases (MAPKs) and NF-κB pathways.