Effect of the Natural Product Triptolide on Pancreatic Cancer: A Systematic Review of Preclinical Studies

Natural products as inhibitors against pancreatic cancer cell proliferation and invasion: possible mechanisms

Pancreatic cancer is one of the gastrointestinal tumors with the lowest survival rate and the worst prognosis. At the time of diagnosis, the majority of patients have missed the opportunity for radical surgical resection and opt for chemotherapy as their primary treatment choice. And drug resistance emerges during the application of the most widely used chemotherapeutic regimens such as modified FOLFIRINOX regimen, gemcitabine monotherapy or 5-Fluorouracil combination therapy, which further reduces the therapeutic efficacy. Therefore, it is urgent to explore better treatment strategies for pancreatic cancer. In recent years, more and more studies have found that natural products have significant anti-pancreatic cancer properties. In this paper, we reviewed the possible mechanisms by which natural products inhibit the proliferation and invasion of pancreatic cancer cells, including the possible mechanisms of targeting the inhibition of the growth and proliferation regulatory pathways of pancreatic cancer cells, inducing apoptosis and autophagy of pancreatic cancer cells, inhibiting the EMT process of pancreatic cancer cells, and inhibiting the angiogenesis of pancreatic cancer. Meanwhile, natural products have also hindered the progress of their basic and clinical research due to the complexity of their composition and the limitation of biological extraction technology. Further exploration of the specific molecular mechanisms of natural products to inhibit the proliferation and invasion of pancreatic cancer cells, optimization of purification and preparation techniques, and enrichment of basic and clinical trials to verify their efficacy and safety may be the future direction of natural products in the field of anti-pancreatic cancer research.

Advances in the treatment of pancreatic cancer with traditional Chinese medicine

Pancreatic cancer is a common malignancy of the digestive system. With a high degree of malignancy and poor prognosis, it is called the "king of cancers." Currently, Western medicine treats pancreatic cancer mainly by surgical resection, radiotherapy, and chemotherapy. However, the curative effect is not satisfactory. The application of Traditional Chinese Medicine (TCM) in the treatment of pancreatic cancer has many advantages and is becoming an important facet of comprehensive clinical treatment. In this paper, we review current therapeutic approaches for pancreatic cancer. We also review the protective effects shown by TCM in different models and discuss the potential molecular mechanisms of these.

Focusing on the Role of Natural Products in Overcoming Cancer Drug Resistance: An Autophagy-Based Perspective

Autophagy is a critical cellular adaptive response in tumor formation. Nutritional deficiency and hypoxia exacerbate autophagic flux in established malignancies, promoting tumor cell proliferation, migration, metastasis, and resistance to therapeutic interventions. Pro-survival autophagy inhibition may be a promising treatment option for advanced cancer. Furthermore, excessive or persistent autophagy is cytotoxic, resulting in tumor cell death. Targeted autophagy activation has also shown significant promise in the fight against tumor drug resistance. Several research groups have examined the ability of natural products (NPs) such as alkaloids, terpenoids, polyphenols, and anthraquinones to serve as autophagy inhibitors or activators. The data support the capacity of NPs that promote lethal autophagy or inhibit pro-survival autophagy from being employed against tumor drug resistance. This paper discusses the potential applications of NPs that regulate autophagy in the fight against tumor drug resistance, some limitations of the current studies, and future research needs and priorities.

Exploring the Pharmacological Mechanisms of Tripterygium wilfordii Hook F against Cardiovascular Disease Using Network Pharmacology and Molecular Docking

Background

Tripterygium wilfordii Hook F (TwHF) has been used in traditional Chinese medicine (TCM) for treating cardiovascular disease (CVD). However, the underlying pharmacological mechanisms of the effects of TwHF on CVD remain elusive. This study revealed the pharmacological mechanisms of TwHF acting on CVD based on a pharmacology approach.

Materials and Methods

The active compounds were selected from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database according to the absorption, distribution, metabolism, and excretion (ADME). The potential targets of TwHF were obtained from the SwissTargetPrediction database. The CVD-related therapeutic targets were collected from the DrugBank, the GeneCards database, and the OMIM database. Protein–protein interaction (PPI) network was generated by the STITCH database. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed by R package. The network of drug-targets-diseases-pathways was constructed by the Cytoscape software.

Results

The 41 effective ingredients of TwHF and the 178 common targets of TwHF and CVD-related were collected. Furthermore, AKT1, amyloid precursor protein (APP), mitogen-activated protein kinase 1 (MAPK), phosphatidylinositol 3-kinase catalytic subunit alpha (PIK3CA), and cellular tumor antigen p53 (TP53) were identified as the core targets involved in the mechanism of TwHF on CVD. Top ten GO (biological processes, cellular components, and molecular functions) and KEGG pathways were screened with a P value ≤0.01. Finally, we constructed the network of TwHF-targets-CVD-GO-KEGG.

Conclusions

These findings demonstrate that the main active compound of TwHF, the core targets, and pathways maybe provide new insights into the development of a natural therapy for the prevention and treatment of CVD.

Terpenoids' anti-cancer effects: focus on autophagy

Terpenoids are the largest class of natural products, most of which are derived from plants. Amongst their numerous biological properties, their anti-tumor effects are of interest for they are extremely diverse which include anti-proliferative, apoptotic, anti-angiogenic, and anti-metastatic activities. Recently, several in vitro and in vivo studies have been dedicated to understanding the 'terpenoid induced autophagy' phenomenon in cancer cells. Light has already been shed on the intricacy of apoptosis and autophagy relationship. This latter crosstalk is driven by the delicate balance between activating or silencing of certain proteins whereby the outcome is expressed via interrelated signaling pathways. In this review, we focus on nine of the most studied terpenoids and on their cell death and autophagic activity. These terpenoids are grouped in three classes: sesquiterpenoid (artemisinin, parthenolide), diterpenoids (oridonin, triptolide), and triterpenoids (alisol, betulinic acid, oleanolic acid, platycodin D, and ursolic acid). We have selected these nine terpenoids among others as they belong to the different major classes of terpenoids and our extensive search of the literature indicated that they were the most studied in terms of autophagy in cancer. These terpenoids alone demonstrate the complexity by which these secondary metabolites induce autophagy via complex signaling pathways such as MAPK/ERK/JNK, PI3K/AKT/mTOR, AMPK, NF-kB, and reactive oxygen species. Moreover, induction of autophagy can be either destructive or protective in tumor cells. Nevertheless, should this phenomenon be well understood, we ought to be able to exploit it to create novel therapies and design more effective regimens in the management and treatment of cancer.

Development of Potential Antitumor Agents from the Scaffolds of Plant-Derived Terpenoid Lactones

Naturally occurring terpenoid lactones and their synthetic derivatives have attracted increasing interest for their promising antitumor activity and potential utilization in the discovery and design of new antitumor agents. In the present perspective article, selected plant-derived five-membered γ-lactones and six-membered δ-lactones that occur with terpenoid scaffolds are reviewed, with their structures, cancer cell line cytotoxicity and in vivo antitumor activity, structure-activity relationships, mechanism of action, and the potential for developing cancer chemotherapeutic agents discussed in each case. The compounds presented include artemisinin (ART, 1), parthenolide (PTL, 2), thapsigargin (TPG, 3), andrographolide (AGL, 4), ginkgolide B (GKL B, 5), jolkinolide B (JKL B, 6), nagilactone E (NGL E, 7), triptolide (TPL, 8), bruceantin (BRC, 9), dichapetalin A (DCT A, 10), and limonin (LMN, 11), and their naturally occurring analogues and synthetic derivatives. It is hoped that this contribution will be supportive of the future development of additional efficacious anticancer agents derived from natural products.

Pancreatic Cancer (PDAC): Introduction of Evidence-Based Complementary Measures into Integrative Clinical Management

The most common form of pancreatic cancer is pancreatic ductal adenocarcinoma (PDAC), which comprises some 85% of all cases. Currently, this is the fourth highest cause of cancer mortality worldwide and its incidence is rising steeply. Commonly applied clinical therapies offer limited chance of a lasting cure and the five-year survival rate is one of the lowest of the commonly occurring cancers. This review cultivates the hypothesis that the best management of PDAC would be possible by integrating 'western' clinical medicine with evidence-based complementary measures. Protecting the liver, where PDAC frequently first spreads, is also given some consideration. Overall, the complementary measures are divided into three groups: dietary factors, nutraceutical agents and lifestyle. In turn, dietary factors are considered as general conditioners, multi-factorial foodstuffs and specific compounds. The general conditioners are alkalinity, low-glycemic index and low-cholesterol. The multi-factorial foodstuffs comprise red meat, fish, fruit/vegetables, dairy, honey and coffee. The available evidence for the beneficial effects of the specific dietary and nutraceutical agents was considered at four levels (in order of prominence): clinical trials, meta-analyses, in vivo tests and in vitro studies. Thus, 9 specific agents were identified (6 dietary and 3 nutraceutical) as acceptable for integration with gemcitabine chemotherapy, the first-line treatment for pancreatic cancer. The specific dietary agents were the following: Vitamins A, C, D and E, genistein and curcumin. As nutraceutical compounds, propolis, triptolide and cannabidiol were accepted. The 9 complementary agents were sub-grouped into two with reference to the main 'hallmarks of cancer'. Lifestyle factors covered obesity, diabetes, smoking, alcohol and exercise. An integrative treatment regimen was devised for the management of PDAC patients. This involved combining first-line gemcitabine chemotherapy with the two sub-groups of complementary agents alternately in weekly cycles. The review concludes that integrated management currently offers the best patient outcome. Opportunities to be investigated in the future include emerging modalities, precision medicine, the nerve input to tumors and, importantly, clinical trials.

Apoptosis Exerts a Vital Role in the Treatment of Colitis-Associated Cancer by Herbal Medicine

Colitis-associated cancer (CAC) is known as inflammatory bowel disease (IBD)-developed colorectal cancer, the pathogenesis of which involves the occurrence of apoptosis. Western drugs clinically applied to CAC are often single-targeted and exert many adverse reactions after long-term administration, so it is urgent to develop new drugs for the treatment of CAC. Herbal medicines commonly have multiple components with multiple targets, and most of them are low-toxicity. Some herbal medicines have been reported to ameliorate CAC through inducing apoptosis, but there is still a lack of systematic review. In this work, we reviewed articles published in Sci Finder, Web of Science, PubMed, Google Scholar, CNKI, and other databases in recent years by setting the keywords as apoptosis in combination with colitis-associated cancer. We summarized the herbal medicine extracts or their compounds that can prevent CAC by modulating apoptosis and analyzed the mechanism of action. The results show the following. (1) Herbal medicines regulate both the mitochondrial apoptosis pathway and death receptor apoptosis pathway. (2) Herbal medicines modulate the above two apoptotic pathways by affecting signal transductions of IL-6/STAT3, MAPK/NF-κ B, Oxidative stress, Non-canonical TGF-β1, WNT/β-catenin, and Cell cycle, thereby ameliorating CAC. We conclude that following. (1) Studies on the role of herbal medicine in regulating apoptosis through the Ras/Raf/ERK, WNT/β-catenin, and Cell cycle pathways have not yet been carried out in sufficient depth. (2) The active constituents of reported anti-CAC herbal medicine mainly include polyphenols, terpenoids, and saccharide. Also, we identified other herbal medicines with the constituents mentioned above as their main components, aiming to provide a reference for the clinical use of herbal medicine in the treatment of CAC. (3) New dosage forms can be utilized to elevate the targeting and reduce the toxicity of herbal medicine.

Discovery of potential targets of Triptolide through inverse docking in ovarian cancer cells

Triptolide (TPL) is proposed as an effective anticancer agent known for its anti-proliferation of a variety of cancer cells including ovarian cancer cells. Although some studies have been conducted, the mechanism by which TPL acts on ovarian cancer remains to be clearly described. Herein, systematic work based on bioinformatics was carried out to discover the potential targets of TPL in SKOV-3 cells. TPL induces the early apoptosis of SKOV-3 cells in a dose- and time-dependent manner with an IC₅₀ = 40 ± 0.89 nM when cells are incubated for 48 h. Moreover, 20 nM TPL significantly promotes early apoptosis at a rate of 40.73%. Using a self-designed inverse molecular docking protocol, we fish the top 19 probable targets of TPL from the target library, which was built on 2,250 proteins extracted from the Protein Data Bank. The 2D-DIGE assay reveals that the expression of eight genes is affected by TPL. The results of western blotting and qRT-PCR assay suggest that 40 nM of TPL up-regulates the level of Annexin A5 (6.34 ± 0.07 fold) and ATP syn thase (4.08 ± 0.08 fold) and down-regulates the level of β-Tubulin (0.11 ± 0.12 fold) and HSP90 (0.21 ± 0.09 fold). More details of TPL affecting on Annexin A5 signaling pathway will be discovered in the future. Our results define some potential targets of TPL, with the hope that this agent could be used as therapy for the preclinical treatment of ovarian cancer.

RETRACTED: Triptolide inhibits the growth and migration of colon carcinoma cells by down-regulation of miR-191

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concerns were raised about the background pattern of the Western Blots from Figure 2A. Given the comments of Dr Elisabeth Bik regarding this article “This paper belongs to a set of over 400 papers (as per February 2020) that share very similar Western blots with tadpole-like shaped bands, the same background pattern, and striking similarities in title structures, paper layout, bar graph design, and - in a subset - flow cytometry panels”, the journal requested the authors to provide the raw data. However, the authors were not able to fulfil this request and therefore the Editor-in-Chief decided to retract the article.

Anti-oral cancer effects of triptolide by downregulation of DcR3 in vitro, in vivo, and in preclinical patient-derived tumor xenograft model

Background

Aberrant expression of decoy receptor 3 (DcR3) is considered to be a diagnostic and therapeutic target for human cancers. The aim of this study was to assess DcR3 as a target of the anticancer effects of triptolide (TPL) in preclinical patient‐derived tumor xenograft (PDTX) models of oral squamous cell carcinoma (OSCC).

Methods

The expression of DcR3 was evaluated through immunohistochemistry, and correlations were examined using clinical variables. The effects of TPL on the expression of DcR3 and cell proliferation were investigated in OSCC cell lines and in PDTX models.

Results

DcR3 overexpression was associated with overall survival and tumor size. TPL significantly decreased tumor growth. Moreover, TPL inhibited the expression of metastasis‐associated protein 1 (MTA1), a transcription factor for DcR3 in vivo, in vitro, and in PDTX models.

Conclusion

TPL appeared to exert anticancer effects by repressing DcR3 and MTA1 in vitro, in vivo, and in PDTX models.

Triptolide Decreases Cell Proliferation and Induces Cell Death in Triple Negative MDA-MB-231 Breast Cancer Cells

Triple negative breast cancers (TNBCs) do not respond to conventional estrogen receptor/progesterone receptor/human epidermal growth factor receptor-2 targeted interventions due to the absence of the respective receptor targets. They are aggressive, exhibit early recurrence, metastasize, are more invasive in nature, and develop drug resistance. Some plant-derived substances have been screened and have gained attention as efficient anticancer drugs for TNBCs with few adverse effects. Here, we evaluate triptolide (concentrations in the range of 100 pM to 10 µM), a di-terpene tri-epoxide isolated from thunder god vine for its efficacy as anticancer drug in MDA-MB-231 TNBC cells. Cell proliferation and viability were assessed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay and trypan blue exclusion assay, respectively. A flow cytometry-based apoptosis assay was performed by using fluorescein isothiocyanate (FITC)-conjugated annexin V and propidium iodide (PI). Western blotting was performed to determine the levels of apoptotic and autophagy proteins such as caspase 3, LC3B and SQSTM1/p62. Results indicate that in 72 h of 1 nM triptolide treatment, the percentage of cell proliferation in MDA-MB-231 cells declined to 49 ± 18.9% (mean ± standard deviation (SD)), whereas the proliferation rate did not drop below 80% in MCF-7 cells (non-TNBC cells which express the estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2) even at the highest concentration tested (10 µM). The MDA-MB-468 cells showed a similar trend to MDA-MB-231 cells. Furthermore, triptolide treatment for 72 h significantly decreased cell viability at concentrations above 10 nM. Apoptotic cell death assay in 72 h triptolide-treated MDA-MB-231 cells revealed 29.3 ± 10.57% of early apoptotic cells in comparison to the control group (4.61 ± 2.24%). Cell cycle analysis indicated accumulation of cells in sub G₀/G₁ phase, indicating apoptosis. Western blot analysis in the 25 nM triptolide treatment group revealed induction of autophagy as shown by a significant decrease in the levels of autophagy marker p62 (by 0.2-fold p < 0.0001) and with an increase in the levels of LC3B-II (by 8-fold p < 0.05). An increase in the levels of the apoptotic marker cleaved caspase 3 (by 4-fold p < 0.05) was also observed in triptolide treated MDA-MB-231 cells. Our data shows that triptolide could be an efficient anticancer agent in the treatment of TNBCs.

In vivo protective effects of chlorogenic acid against triptolide-induced hepatotoxicity and its mechanism

CONTEXT

Triptolide (TP) has outstanding biological activities, but it induces toxicities, particular hepatotoxicity, severely limiting its clinical application. Chlorogenic acid (CGA) has prominently medicinal and nutritional values. However, until now, it is not known whether CGA could mitigate TP-induced hepatotoxicity.

OBJECTIVE

This study explored the possible protection of CGA against TP-induced hepatotoxicity and its potential mechanisms, for the first time.

MATERIAL AND METHODS

KM mice were treated orally with TP at a single dose of 1 mg/kg at 4 h after being treated with CGA (10, 20 and 40 mg/kg) for seven continuous days. Blood samples were collected at 24 h after TP administration for measurement of serum biomarkers, and hepatic tissues for analysis of potential mechanisms.

RESULTS

TP treatment-induced acute hepatotoxicity manifested by the significant elevation in serum alanine transaminase (93.9 U/L), aspartate transaminase (185.8 U/L) and hepatic malondialdehyde (0.637 μmol/mg protein), and the remarkable reduction in hepatic glutathione (1.425 μg/mg protein), glutathione S-transferase, glutathione peroxidase, superoxide dismutase and catalase (91.7, 320.7, 360.6 and 140.7 U/mg protein, respectively). In contrast, pretreatment with CGA for 7 days effectively attenuated acute liver injury and oxidative stress caused by TP with each ED₅₀ of 44.4, 57.1, 46.6, 22.2, 40.9, 58.1, 86.4 and 61.0 mg/kg, respectively. Furthermore, pretreatment with CGA promoted the accumulation of Nrf2 into the nucleus, and up-regulated mRNA expression of Nrf2-target downstream genes.

DISCUSSION AND CONCLUSIONS

Combined CGA medication may probably reduce the risk of TP poisoning, and in-depth mechanisms can be developed around the signal molecules of Nrf2.

Griffipavixanthone induces apoptosis of human breast cancer MCF-7 cells in vitro

BACKGROUND

Griffipavixanthone (GPX) is a compound extracted from Garcinia oblongifolia Champ. But, no research has yet been done about the effect of GPX on breast cancer.

METHODS

We evaluated the proliferation of human breast cancer cells by CCK-8 assay and apoptosis by Annexin V (AV)-FITC and PI double staining. We used transwell assay to indicate the invasion and migration of MCF-7. To explore the molecular mechanism of GPX, we detected the mRNA and protein expression using qRT-PCR and Western blot.

RESULTS

In this study, we evaluated if GPX could inhibit the proliferation of human breast cancer cell MCF-7 and T-47D with IC50 value of 9.64 ± 0.12 µM and 10.2 1 ± 0.38 µM at 48 h. And the IC50 value of MCF-10A is 32.11 ± 0.21 µM, which showed GPX had a tiny side effect for normal breast cells. Annexin V (AV)-FITC and PI double staining demonstrated firmly the apoptosis of MCF-7 resulting from GPX. Transwell assay indicated that GPX inhibited the invasion and migration of MCF-7. In addition, we found GPX cleaved caspase-8/9 and PARP, which play important roles in apoptotic pathway. Furthermore, through the Western blot assay, GPX increased the level of pro-apoptosis protein Bax and cytochrome C. On the contrary, GPX decreased the level of anti-apoptosis protein Bcl-2. Moreover, GPX increased the mRNA and protein expression level of p53 and its target genes, which indicated that GPX induced MCF-7 cell apoptosis by up-regulating p53 and Bax expression while suppressing Bcl-2 expression.

CONCLUSION

All the results showed that GPX induces MCF-7 cell apoptosis and could be considered as a potential drug for breast cancer.

Ganglioside GD3 synthase (GD3S), a novel cancer drug target

Gangliosides are a class of important glycosphingolipids containing sialic acid that are widely distributed on the outer surface of cells and are abundantly distributed in brain tissue. Disialoganglioside with three glycosyl groups (GD3) and disialoganglioside with two glycosyl groups (GD2) are markedly increased in pathological conditions such as cancers and neurodegenerative diseases. GD3 and GD2 were found to play important roles in cancers by mediating cell proliferation, migration, invasion, adhesion, angiogenesis and in preventing immunosuppression of tumors. GD3 synthase (GD3S) is the regulatory enzyme of GD3 and GD2 synthesis, and is important in tumorigenesis and the development of cancers. The study of GD3S as a drug target may be of great significance for the discovery of new drugs for cancer treatment. This review will describe the gangliosides and their roles in physiological and pathological conditions; the roles of GD3 and GD2 in cancers; the expression, functions and mechanisms of GD3S, and its potential as a drug target in cancers.

[Monoside antagonizes triptolide-induced hepatocyte apoptosis via the anti-oxidative stress pathway]

OBJECTIVE

To investigate the protective effect of monoside against triptolide-induced liver injury and explore its molecular mechanism.

METHODS

BALB/C mice treated with gastric lavage with triptolide and monoside, either alone or in combination, were examined for changes of hepatic biochemical parameters using the serological method. The growth inhibition rate of HepG2 cells treated with triptolide or monoside or both was assessed with MTT assay, and the cell morphological changes were observed using laser confocal microscopy; the expressions of the target proteins in the antioxidative stress pathway were detected using flow cytometry and Western blotting.

RESULTS

In BALB/C mice, gastric lavage of triptolide induced obvious hepatic damage. In HepG2 cells, treatment with triptolide significantly inhibited the cell growth, resulting in a cell viability as low as 72.83% at 24 h; triptolide also induced obvious cell apoptosis and cell nucleus deformation, causing an apoptosis rate of 43.1% in the cells at 24 h. Triptolide significantly reduced the expressions of Nrf2 and HO-1 proteins related with the oxidative stress pathway. Combined treatment with morroniside obviously reversed these changes, resulting in significantly decreased hepatic biochemical parameters and the liver index in BALB/C mice and in significantly lowered cell apoptosis rate, improved cell morphology, and increased Nrf2 and HO-1 protein expressions in HepG2 cells.

CONCLUSIONS

Monoside protects against triptolide-induced liver injury possibly by relieving oxidative stress.