Synergistic Antitumor Effect of Triptolide and Cisplatin in Cisplatin Resistant Human Bladder Cancer Cells

Excavatolide C/cisplatin combination induces antiproliferation and drives apoptosis and DNA damage in bladder cancer cells

Excavatolide C (EXCC), a marine coral-derived compound, exhibits an antiproliferation effect on bladder cancer cells. The present study evaluated the improvement in the antiproliferation ability of EXCC by co-treatment with cisplatin in bladder cancer cells. EXCC/cisplatin (12.5 and 1 μg/mL) showed higher antiproliferation effects on bladder cancer cells than single treatments (EXCC or cisplatin alone) in the 48 h ATP assay. EXCC/cisplatin also enhanced the increase in subG1, annexin V-mediated apoptosis, and activation of poly (ADP-ribose) polymerase (PARP) and several caspases (caspases 3, 8, and 9) compared to the single treatments. Cellular and mitochondrial oxidative stress was enhanced with EXCC/cisplatin compared to the single treatments according to analyses of reactive oxygen species (ROS), mitochondrial superoxide, and mitochondrial membrane potential; in addition, cellular antioxidants, such as glutathione (GSH), and the mRNA expressions of antioxidant signaling genes (catalase and NFE2-like bZIP transcription factor 2) were downregulated. EXCC/cisplatin treatment produced more DNA damage than the single treatments, as indicated by γH2AX and 8-hydroxy-2'-deoxyguanosine levels. Moreover, several DNA repair genes for homologous recombination (HR) and non-homologous end joining (NHEJ) were downregulated in EXCC/cisplatin compared to others. The addition of the GSH precursor N-acetylcysteine, which has ROS scavenging activity, attenuated all EXCC/cisplatin-induced changes. Notably, EXCC/cisplatin showed lower antiproliferation, apoptosis, ROS induction, GSH depletion, and γH2AX DNA damage in normal cells than in bladder cancer cells. Therefore, the co-treatment of EXCC/cisplatin reduces the proliferation of bladder cancer cells via oxidative stress-mediated mechanisms with normal cell safety.

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

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

Natural biomolecules and derivatives as anticancer immunomodulatory agents

Despite advancements in chemotherapy, the issue of resistance and non-responsiveness to many chemotherapeutic drugs that are currently in clinical use still remains. Recently, cancer immunotherapy has gathered attention as a novel treatment against select cancers. Immunomodulation is also emerging as an effective strategy to improve efficacy. Natural phytochemicals, with known anticancer properties, been reported to mediate their effects by modulating both traditional cancer pathways and immunity. The mechanism of phytochemical mediated-immunomodulatory activity may be attributed to the remodeling of the tumor immunosuppressive microenvironment and the sensitization of the immune system. This allows for improved recognition and targeting of cancer cells by the immune system and synergy with chemotherapeutics. In this review, we will discuss several well-known plant-derived biomolecules and examine their potential as immunomodulators, and therefore, as novel immunotherapies for cancer treatment.

Nano-drug co-delivery system of natural active ingredients and chemotherapy drugs for cancer treatment: a review

Chemotherapy drugs have been used for a long time in the treatment of cancer, but serious side effects are caused by the inability of the drug to be solely delivered to the tumor when treating cancer with chemotherapy. Natural products have attracted more and more attention due to the antitumor effect in multiple ways, abundant resources and less side effects. Therefore, the combination of natural active ingredients and chemotherapy drugs may be an effective antitumor strategy, which can inhibit the growth of tumor and multidrug resistance, reduce side effects of chemotherapy drugs. Nano-drug co-delivery system (NDCDS) can play an important role in the combination of natural active ingredients and chemotherapy drugs. This review provides a comprehensive summary of the research status and application prospect of nano-delivery strategies for the combination of natural active ingredients and chemotherapy drugs, aiming to provide a basis for the development of anti-tumor drugs.

Minnelide synergizes with conventional chemotherapy by targeting both cancer and associated stroma components in pancreatic cancer

Addition of nab-paclitaxel to gemcitabine offers a survival benefit of only 6 weeks over gemcitabine alone at a cost of increased toxicity in PDAC. The goal of the present study is to evaluate the efficacy of Minnelide, a water-soluble prodrug of triptolide, in combination with the standard of care regimen for chemotherapy with the added advantage of reducing the doses of these drugs to minimize toxicity. Pancreatic cancer cell lines were implanted subcutaneously or orthotopically in athymic nude or C57BL/6J mice. Subsequently, animals were randomized and received saline or minnelide or full dose chemotherapy or low dose chemotherapy or minnelide in combination with low dose chemotherapy. Our results show that a combination of low doses of Minnelide with Gemcitabine + nab-paclitaxel significantly inhibited tumor progression and increased the survival of tumor-bearing mice in comparison with conventional chemotherapy alone. Moreover, combination therapy significantly reduced cancer-related morbidity by decreasing ascites and metastasis and effectively targeted both cancer and the associated stroma. In vitro studies with a combination of low doses of triptolide and paclitaxel significantly decreased the cell viability, increased apoptosis and led to significantly increased M-phase cell cycle arrest in various pancreatic cancer cell lines as compared to either drug alone. Our results show that Minnelide synergizes with conventional chemotherapy leading to a significant reduction in the doses of these toxic drugs, all the while achieving better efficacy in the treatment of PDAC. This combination effectively targeted both the cancer and the associated stromal components of pancreatic cancer.

Synergistic Antiproliferation of Cisplatin and Nitrated [6,6,6]Tricycle Derivative (SK2) for a Combined Treatment of Oral Cancer Cells

SK2, a nitrated [6,6,6]tricycle derivative with an n-butyloxy group, showed selective antiproliferation effects on oral cancer but not on normal oral cells. This investigation assessed for the first time the synergistic antiproliferation potential of cisplatin/SK2 in oral cancer cells. Cell viability assay at 24 h showed that a low dose of combined cisplatin/SK2 (10 μM/10 μg/mL) provided more antiproliferation than cisplatin or SK2 alone. Cisplatin/SK2 triggered also more apoptosis inductions in terms of subG1 accumulation, annexin V, pancaspase, and caspase 3/8/9 measurements. Moreover, cisplatin/SK2 provided more oxidative stress and DNA damage in oral cancer cells than independent treatments. Oxidative stress inhibitors rescued the cisplatin/SK2-induced antiproliferation and oxidative stress generation. Moreover, cisplatin/SK2 induced more antiproliferation, apoptosis, oxidative stress, and DNA damage in oral cancer cells than in normal oral cells (S-G). In conclusion, low-dose cisplatin/SK2 combined treatment promoted selective and synergistic antiproliferation in oral cancer cells depending on oxidative-stress-associated responses.

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.

Exosome-liposome hybrid nanoparticle codelivery of TP and miR497 conspicuously overcomes chemoresistant ovarian cancer

Background

Although cisplatin-based chemotherapy has been used as the first-line treatment for ovarian cancer (OC), tumor cells develop resistance to cisplatin during treatment, causing poor prognosis in OC patients. Studies have demonstrated that overactivation of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway is involved in tumor chemoresistance and that overexpression of microRNA-497 (miR497) may overcome OC chemotherapy resistance by inhibiting the mTOR pathway. However, the low transcriptional efficiency and unstable chemical properties of miR497 limit its clinical application. Additionally, triptolide (TP) was confirmed to possess a superior killing effect on cisplatin-resistant cell lines, partially through inhibiting the mTOR pathway. Even so, the clinical applications of TP are restricted by serious systemic toxicity and weak water solubility.

Results

Herein, whether the combined application of miR497 and TP could further overcome OC chemoresistance by synergically suppressing the mTOR signaling pathway was investigated. Bioinspired hybrid nanoparticles formed by the fusion of CD47-expressing tumor exosomes and cRGD-modified liposomes (miR497/TP-HENPs) were prepared to codeliver miR497 and TP. In vitro results indicated that the nanoparticles were efficiently taken up by tumor cells, thus significantly enhancing tumor cell apoptosis. Similarly, the hybrid nanoparticles were effectively enriched in the tumor areas and exerted significant anticancer activity without any negative effects in vivo. Mechanistically, they promoted dephosphorylation of the overactivated PI3K/AKT/mTOR signaling pathway, boosted reactive oxygen species (ROS) generation and upregulated the polarization of macrophages from M2 to M1 macrophages.

Conclusion

Overall, our findings may provide a translational strategy to overcome cisplatin-resistant OC and offer a potential solution for the treatment of other cisplatin-resistant tumors.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01264-5.

A pH-sensitive supramolecular nanosystem with chlorin e6 and triptolide co-delivery for chemo-photodynamic combination therapy

The combination of Ce6, an acknowledged photosensitizer, and TPL, a natural anticancer agent, has been demonstrated as a useful strategy to reinforce the tumor growth suppression, as well as decrease the systemic side effects compared with their monotherapy. However, in view of the optimal chemo-photodynamic combination efficiency, there is still short of the feasible nanovehicle to steadily co-deliver Ce6 and TPL, and stimuli-responsively burst release drugs in tumor site. Herein, we described the synergistic antitumor performance of a pH-sensitive supramolecular nanosystem, mediated by the host–guest complexing between β-CD and acid pH-responsive amphiphilic co-polymer mPEG-PBAE-mPEG, showing the shell–core structural micelles with the tight β-CD layer coating. Both Ce6 and TPL were facilely co-loaded into the spherical supramolecular NPs (TPL+Ce6/NPs) by one-step nanoprecipitation method, with an ideal particle size (156.0 nm), acid pH-responsive drug release profile, and enhanced cellular internalization capacity. In view of the combination benefit of photodynamic therapy and chemotherapy, as well as co-encapsulation in the fabricated pH-sensitive supramolecular NPs, TPL+Ce6/NPs exhibited significant efficacy to suppress cellular proliferation, boost ROS level, lower MMP, and promote cellular apoptosis in vitro. Particularly, fluorescence imaging revealed that TPL+Ce6/NPs preferentially accumulated in the tumor tissue area, with higher intensity than that of free Ce6. As expected, upon 650-nm laser irradiation, TPL+Ce6/NPs exhibited a cascade of amplified synergistic chemo-photodynamic therapeutic benefits to suppress tumor progression in both hepatoma H22 tumor-bearing mice and B16 tumor-bearing mice. More importantly, lower systemic toxicity was found in the tumor-bearing mice treated with TPL+Ce6/NPs. Overall, the designed supramolecular TPL+Ce6/NPs provided a promising alternative approach for chemo-photodynamic therapy in tumor treatment.

Emerging strategies for the improvement of chemotherapy in bladder cancer: Current knowledge and future perspectives

•

The response of chemotherapy and prognosis in bladder cancer is unsatisfied.

•

Immunotherapy, targeted therapy, and ADC improve the efficacy of chemotherapy.

•

Emerging targets in cancer cells and TME spawned novel preclinical agents.

•

Novel drug delivery, such as nanotechnology, enhances effects of chemotherapeutics.

•

The organoid and PDX model are promising to screen and evaluate the target therapy.

Background

Chemotherapy is a first-line treatment for advanced and metastatic bladder cancer, but the unsatisfactory objective response rate to this treatment yields poor 5-year patient survival. Only PD-1/PD-L1-based immune checkpoint inhibitors, FGFR3 inhibitors and antibody-drug conjugates are approved by the FDA to be used in bladder cancer, mainly for platinum-refractory or platinum-ineligible locally advanced or metastatic urothelial carcinoma. Emerging studies indicate that the combination of targeted therapy and chemotherapy shows better efficacy than targeted therapy or chemotherapy alone. Newly identified targets in cancer cells and various functions of the tumour microenvironment have spawned novel agents and regimens, which give impetus to sensitizing chemotherapy in the bladder cancer setting.

Aim of Review

This review aims to present the current evidence for potentiating the efficacy of chemotherapy in bladder cancer. We focus on combining chemotherapy with other treatments as follows: targeted therapy, including immunotherapy and antibody-drug conjugates in clinic; novel targeted drugs and nanoparticles in preclinical models and potential targets that may contribute to chemosensitivity in future clinical practice. The prospect of precision therapy is also discussed in bladder cancer.

Key Scientific Concepts of Review

Combining chemotherapy drugs with immune checkpoint inhibitors, antibody-drug conjugates and VEGF inhibitors potentially elevates the response rate and survival. Novel targets, including cancer stem cells, DNA damage repair, antiapoptosis, drug metabolism and the tumour microenvironment, contribute to chemosensitization. Gene alteration-based drug selection and patient-derived xenograft- and organoid-based drug validation are the future for precision therapy.

MEK is a promising target in the basal subtype of bladder cancer

While many resources exist for the drug screening of bladder cancer cell lines in 2D culture, it is widely recognized that screening in 3D culture is more representative of in vivo response. Importantly, signaling changes between 2D and 3D culture can result in changes to drug response. To address the need for 3D drug screening of bladder cancer cell lines, we screened 17 bladder cancer cell lines using a library of 652 investigational small-molecules and 3 clinically relevant drug combinations in 3D cell culture. Our goal was to identify compounds and classes of compounds with efficacy in bladder cancer. Utilizing established genomic and transcriptomic data for these bladder cancer cell lines, we correlated the genomic molecular parameters with drug response, to identify potentially novel groups of tumors that are vulnerable to specific drugs or classes of drugs. Importantly, we demonstrate that MEK inhibitors are a promising targeted therapy for the basal subtype of bladder cancer, and our data indicate that drug screening of 3D cultures provides an important resource for hypothesis generation.

Study on the chemodrug-induced effect in nasopharyngeal carcinoma cells using laser tweezer Raman spectroscopy

To explore the effect in nasopharyngeal carcinoma (NPC) cells after treatment with chemodrugs, Raman profiles were characterized by laser tweezer Raman spectroscopy. Two NPC cell lines (CNE2 and C666-1) were treated with gemcitabine, cisplatin, and paclitaxel, respectively. The high-quality Raman spectra of cells without or with treatments were recorded at the single-cell level with label-free laser tweezers Raman spectroscopy (LTRS) and analyzed for the differences of alterations of Raman profiles. Tentative assignments of Raman peaks indicated that the cellular specific biomolecular changes associated with drug treatment include changes in protein structure (e.g. 1655 cm^-1), changes in DNA/RNA content and structure (e.g. 830 cm^-1), destruction of DNA/RNA base pairs (e.g. 785 cm^-1), and reduction in lipids (e.g. 970 cm^-1). Besides, both principal components analysis (PCA) combined with linear discriminant analysis (LDA) and the classification and regression trees (CRT) algorithms were employed to further analyze and classify the spectral data between control group and treated group, with the best discriminant accuracy of 96.7% and 90.0% for CNE2 and C666-1 group treated with paclitaxel, respectively. This exploratory work demonstrated that LTRS technology combined with multivariate statistical analysis has promising potential to be a novel analytical strategy at the single-cell level for the evaluation of NPC-related chemotherapeutic drugs.

Triptolide inhibits epithelial‑mesenchymal transition and induces apoptosis in gefitinib‑resistant lung cancer cells

The epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), gefitinib, is used widely to treat non-small cell lung cancer (NSCLC) with EGFR-activating mutations. Unfortunately, the acquired drug resistance promoted by epithelial-mesenchymal transition (EMT) markedly limits the clinical effects and remains a major barrier to a cure. Our previous isobaric tags for relative and absolute quantitation-based proteomics analysis revealed that the E-cadherin protein level was markedly upregulated by triptolide (TP). The present study aimed to determine whether TP reverses the gefitinib resistance of human lung cancer cells by regulating EMT. It was revealed that TP combined with gefitinib synergistically inhibited the migration and invasion of lung adenocarcinoma cell line A549; the combination treatment had a significantly better outcome than that of TP and gefitinib alone. Moreover, TP effectively increased the sensitivity of drug resistant A549 cells to gefitinib by upregulating E-cadherin protein expression and downregulating the MMP9, SNAIL, and vimentin expression levels. The dysregulated E-cadherin expression of gefitinib-sensitive cells induced gefitinib resistance, which could be overcome by TP. Finally, TP combined with gefitinib significantly inhibited the growth of xenograft tumors induced using gefitinib-resistant A549 cells, which was associated with EMT reversal and E-cadherin signaling activation in vivo. The present results indicated that the combination of TP and TKIs may be a promising therapeutic strategy to treat patients with NSCLCs harboring EGFR mutations.

Cisplatin Resistance in Osteosarcoma: In vitro Validation of Candidate DNA Repair-Related Therapeutic Targets and Drugs for Tailored Treatments

Treatment of high-grade osteosarcoma, the most common malignant tumor of bone, is largely based on administration of cisplatin and other DNA damaging drugs. Altered DNA repair mechanisms may thus significantly impact on either response or resistance to chemotherapy. In this study, by using a panel of human osteosarcoma cell lines, either sensitive or resistant to cisplatin, we assessed the value as candidate therapeutic targets of DNA repair-related factors belonging to the nucleotide excision repair (NER) or base excision repair (BER) pathways, as well as of a group of 18 kinases, which expression was higher in cisplatin-resistant variants compared to their parental cell lines and may be indirectly involved in DNA repair. The causal involvement of these factors in cisplatin resistance of human osteosarcoma cells was validated through gene silencing approaches and in vitro reversal of CDDP resistance. This approach highlighted a subgroup of genes, which value as promising candidate therapeutic targets was further confirmed by protein expression analyses. The in vitro activity of 15 inhibitor drugs against either these genes or their pathways was then analyzed, in order to identify the most active ones in terms of inherent activity and ability to overcome cisplatin resistance. NSC130813 (NERI02; F06) and triptolide, both targeting NER factors, proved to be the two most active agents, without evidence of cross-resistance with cisplatin. Combined in vitro treatments showed that NSC130813 and triptolide, when administered together with cisplatin, were able to improve its efficacy in both drug-sensitive and resistant osteosarcoma cells. This evidence may indicate an interesting therapeutic future option for treatment of osteosarcoma patients who present reduced responsiveness to cisplatin, even if possible effects of additive collateral toxicities must be carefully considered. Moreover, our study also showed that targeting protein kinases belonging to the mitogen-activated protein kinase (MAPK) or fibroblast growth factor receptor (FGFR) pathways might indicate new promising therapeutic perspectives in osteosarcoma, demanding for additional investigation.

Antitumor effects of MutT homolog 1 inhibitors in human bladder cancer cells

As standard second-line regimen has not been established for patients who are refractory to or relapse with cisplatin-based chemotherapy, an effective class of novel chemotherapeutic agents is needed for cisplatin-resistant bladder cancer. Recent publications reported that MutT homolog 1 (MTH1) inhibitors suppress tumor growth and induce impressive therapeutic responses in a variety of human cancer cells. Few studies investigated the cytotoxic effects of MTH1 inhibitors in human bladder cancer. Accordingly, we investigated the antitumor effects and the possible molecular mechanisms of MTH1 inhibitors in cisplatin-sensitive (T24) and – resistant (T24R2) human bladder cancer cell lines. These results suggest that TH588 or TH287 may induce cancer cell suppression by off-target effects such as alterations in the expression of apoptosis- and cell cycle-related proteins rather than MTH1 inhibition in cisplatin-sensitive and – resistant bladder cancer cells.

Abbreviations: MTH: MutT homolog; ROS: reactive oxygen species; CCK-8: cell counting kit-8; DCFH-DA: dichlorofluorescein diacetate; PARP: poly (ADP-ribose) polymerase

Triptolide inhibits PDGF-induced proliferation of ASMCs through G0/G1 cell cycle arrest and suppression of the AKT/NF-κB/cyclinD1 signaling pathway

Abnormal proliferation of airway smooth muscle cells (ASMCs) is a hallmark of airway remodeling. Platelet-derived growth factor (PDGF) is known to be a major stimulus inducing the proliferation of ASMCs. It has been reported that triptolide demonstrates protective effects against airway remodeling. In this study, we investigated the antiproliferative effects of triptolide on PDGF-induced ASMCs and its underlying mechanisms. Cell proliferation was determined using the Cell Counting Kit-8 (CCK-8) assay. Flow cytometry was used to study the influence of triptolide on cell cycle and apoptosis. Quantitative real-time PCR and Western blot analysis were employed to detect the expression of proliferating cell nuclear antigen (PCNA), cyclinD1 and cyclin dependent kinase 4 (CDK4). Proteins involved in the protein kinase B (AKT) and nuclear factor kappa B (NF-κB) signaling pathways were evaluated using Western blot analysis. Triptolide could significantly inhibit cell proliferation, induce cell cycle arrest in the G0/G1 phase, and reduce the expression of PCNA, cyclinD1, and CDK4 in PDGF-treated ASMCs. Levels of phosphorylated AKT, p65 and NF-κB inhibitor α (IκBα) stimulated by the presence of PDGF were markedly suppressed after triptolide treatment. Moreover, triptolide cotreatment with the phosphatidylinositol 3 kinase (PI3k) inhibitor, 2-(4-morpholinyl)-8-phenylchromone (LY294002), could further suppress the proliferation, NF-κB activation and cyclinD1 expression. Similar results were observed after triptolide cotreatment with the NF-κB inhibitor, ammonium pyrrolidinedithiocarbamate (PDTC). Our results suggest that triptolide could inhibit the PDGF-induced proliferation of ASMCs through G0/G1 cell cycle arrest and suppression of the AKT/NF-κB/cyclinD1 signaling pathway.

Naturally occurring anti-cancer compounds: shining from Chinese herbal medicine

Numerous natural products originated from Chinese herbal medicine exhibit anti-cancer activities, including anti-proliferative, pro-apoptotic, anti-metastatic, anti-angiogenic effects, as well as regulate autophagy, reverse multidrug resistance, balance immunity, and enhance chemotherapy in vitro and in vivo. To provide new insights into the critical path ahead, we systemically reviewed the most recent advances (reported since 2011) on the key compounds with anti-cancer effects derived from Chinese herbal medicine (curcumin, epigallocatechin gallate, berberine, artemisinin, ginsenoside Rg3, ursolic acid, silibinin, emodin, triptolide, cucurbitacin B, tanshinone I, oridonin, shikonin, gambogic acid, artesunate, wogonin, β-elemene, and cepharanthine) in scientific databases (PubMed, Web of Science, Medline, Scopus, and Clinical Trials). With a broader perspective, we focused on their recently discovered and/or investigated pharmacological effects, novel mechanism of action, relevant clinical studies, and their innovative applications in combined therapy and immunomodulation. In addition, the present review has extended to describe other promising compounds including dihydroartemisinin, ginsenoside Rh2, compound K, cucurbitacins D, E, I, tanshinone IIA and cryptotanshinone in view of their potentials in cancer therapy. Up to now, the evidence about the immunomodulatory effects and clinical trials of natural anti-cancer compounds from Chinese herbal medicine is very limited, and further research is needed to monitor their immunoregulatory effects and explore their mechanisms of action as modulators of immune checkpoints.

TFIIH: A multi-subunit complex at the cross-roads of transcription and DNA repair

Transcription factor IIH (TFIIH) is a multiprotein complex involved in both eukaryotic transcription and DNA repair, revealing a tight connection between these two processes. Composed of 10 subunits, it can be resolved into a 7-subunits core complex with the XPB translocase and the XPD helicase, and the 3-subunits kinase complex CAK, which also exists as a free complex with a distinct function. Initially identified as basal transcription factor, TFIIH also participates in transcription regulation and plays a key role in nucleotide excision repair (NER) for opening DNA at damaged sites, lesion verification and recruitment of additional repair factors. Our understanding of TFIIH function in eukaryotic cells has greatly benefited from studies of the genetic rare diseases xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD), that are not only characterized by cancer and aging predispositions but also by neurological and developmental defects. Although much remains unknown about TFIIH function, significant progresses have been done regarding the structure of the complex, the functions of its catalytic subunits and the multiple roles of the regulatory core-TFIIH subunits. This review provides a non-exhaustive survey of key discoveries on the structure and function of this pivotal factor, which can be considered as a promising target for therapeutic strategies.

Notch pathway inhibition using DAPT, a γ-secretase inhibitor (GSI), enhances the antitumor effect of cisplatin in resistant osteosarcoma

Overcoming platinum drug resistance represents a major clinical challenge in osteosarcoma (OS) treatment. The high rates and patterns of therapeutic failure seen in patients are consistent with a steady accumulation of drug-resistant cancer stem cells (CSCs). Notch signaling is implicated in regulating CSCs and tumor resistance to platinum. Thus, we attempt to investigate whether inhibiting of Notch pathway could sensitize cisplatin (CDDP) to CDDP-resistant OS cells and the underlying molecular mechanisms. OS cell lines resistant to CDDP were treated with DAPT, CDDP or combination, we present evidences that DAPT enhances the cytotoxic effect of CDDP in resistant OS by inhibiting proliferation, resulting in G0/G1 cell-cycle arrest, inducing apoptosis, and reducing motility. In addition, DAPT targeting depletes OS stem cells (OSCs), thus increasing tumor sensitivity to platinum, which indicating that a dual combination targeting both OSCs and the bulk of tumor cells are needed for tumor eradication. We also found that the combination of CDDP and DAPT exhibit additive suppression on phosphorylated AKT and ERK, contributing to the anti-cancer effects. In animal model, this combination therapy inhibits the growth and metastasis of CDDP resistant tumor xenografts in nude mice to a greater extent than treatment with either reagent alone. Based on these results, we conclude that CDDP plus DAPT was able to sensitize CDDP-resistant human OS cells to CDDP by downregulation of Notch signaling. CDDP and DAPT combination treatment may be effective and promising for advanced OS.

Triptolide exhibits antitumor effects by reversing hypermethylation of WIF‑1 in lung cancer cells

Triptolide (TP) exhibits numerous biological activities, including immunosuppressive, anti‑inflammatory and antitumor effects. The aim of the present study was to investigate the role of TP as a potent therapeutic drug for the treatment of lung cancer and to investigate the underlying therapeutic mechanisms. Western blot analyses and reverse transcription‑quantitative polymerase chain reaction (PCR) were performed to investigate the expression of genes at transcriptional and translational levels, respectively. Methylation‑specific PCR assays were conducted to investigate whether TP affects the Wnt inhibitory factor‑1 (WIF‑1) methylation status and subsequently affects apoptosis, migration or the invasion of lung cancer cells. The results of the present study revealed that the methylation status of WIF‑1 in lung cancer cell lines A549 and H460 was significantly enhanced compared with the human normal bronchial epithelial cell line HBE, whereas treatment with TP was revealed to induce the demethylation of WIF‑1. The present study aimed to investigate whether the biological activities of TP are regulated by inhibiting the Wnt signaling pathway via an increase in WIF‑1 expression levels. The results of the present study revealed that Wnt signaling was suppressed in cells following treatment with TP, which was concluded by the downregulation of Axin 2 and β‑catenin expression. Further investigation demonstrated that the silencing of WIF‑1 expression with small interfering RNA reversed the TP‑induced upregulation of WIF‑1 expression, upregulated Axin 2 and β‑catenin expression and enhanced the activation of Wnt signaling. Notably, an upregulation of cellular tumor antigen p53 expression, and downregulation of matrix metalloproteinase‑9 (MMP‑9) and phosphorylated‑nuclear factor‑κB (NF‑κB) P65 (p‑P65) levels was observed following TP treatment. These results suggest that the Wnt, p53 and NF‑κB signaling pathways mediate the potent antitumor effects of TP. Notably, the silencing of WIF‑1 did not completely recover the levels of p53, MMP‑9 and p‑P65 in cells treated with TP compared with the control cells, thus suggesting that TP exhibits further functions in addition to the targeting of WIF‑1.

Synergistic effect of black tea polyphenol, theaflavin-3,3'-digallate with cisplatin against cisplatin resistant human ovarian cancer cells

Theaflavin-3, 3'-digallate (TF3) is a phenolic compound extracted from black tea. We previously demonstrated that TF3 selectively inhibited ovarian cancer cells. Ovarian cancer has high death rate because of acquired cisplatin resistance. We aimed to investigate the synergistic effect of TF3 and cisplatin (CDDP) against cisplatin resistant ovarian cancer cells. In the present study, combination treatment with TF3 and CDDP showed a synergistic cytotoxic effect in A2780/CP70 and OVCAR3 cells. Combination treatment showed a synergistic pro-apoptotic effect and synergistically induced G1/S phase cell cycle arrest. Synergistic apoptosis was accompanied by regulating protein expression of cleaved caspase 3/7, cytochrome c, Bax and Bcl-2. Combination treatment induced G1/S phase cell cycle arrest via regulating protein expression of cyclin A2, cyclin D1, cyclin E1 and CDK2/4. Combination treatment could synergistically down-regulate Akt phosphorylation in both cell lines. TF3 may be used as an adjuvant for the treatment of advanced ovarian cancer.

An overview of chemical inhibitors of the Nrf2-ARE signaling pathway and their potential applications in cancer therapy

The Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor regulating a wide array of genes for antioxidant and detoxification enzymes in response to oxidative and xenobiotic stress. A large number of Nrf2-antioxidant response element (ARE) activators have been screened for use as chemopreventive agents in oxidative stress-related diseases and even cancer. However, constitutive activation of Nrf2 occurs in a variety of cancers. Aberrant activation of Nrf2 is correlated with cancer progression, chemoresistance, and radioresistance. In this review, we examine recent studies of Nrf2-ARE inhibitors in the context of cancer therapy. We enumerate the possible Nrf2-inhibiting mechanisms of these compounds, their effects sensitizing cancer cells to chemotherapeutic agents, and the prospect of applying them in clinical cancer therapy.

Synergistic antitumor activity of gemcitabine combined with triptolide in pancreatic cancer cells

Pancreatic cancer is a fatal human malignancy associated with an exceptionally poor prognosis. Novel therapeutic strategies are urgently required to treat this disease. In addition to immunosuppressive activity, triptolide possesses strong antitumor activity and synergistically enhances the antitumor activities of conventional chemotherapeutic drugs in preclinical models of pancreatic cancer. The present study investigated the antitumor effects of triptolide in pancreatic cancer cells, either in combination with gemcitabine, or alone. The pancreatic cancer BxPC-3 and PANC-1 cell lines were treated with triptolide, which resulted in time- and dose-dependent growth arrest. When incorporated into a sequential schedule, triptolide synergistically increased gemcitabine-induced cell growth inhibition and apoptosis, in addition to the cooperative regulation of B-cell lymphoma 2 family proteins and loss of mitochondrial membrane potential. Furthermore, triptolide enhanced gemcitabine-induced S phase arrest and DNA double-strand breaks, possibly through checkpoint kinase 1 suppression. The results of the present study suggest that triptolide has therapeutic potential for the treatment of pancreatic cancer, particularly when administered in combination with gemcitabine.

Triptolide reduces proliferation and enhances apoptosis of human non-small cell lung cancer cells through PTEN by targeting miR-21

Triptolide is used in traditional Chinese medicine. It has the advantages of a unique mechanism of action, a wide antitumor spectrum, multiple targets, multi-channel effects and low toxicity. The current study was conducted to evaluate whether the potential anticancer effects of triptolide reduces proliferation and enhances apoptosis of human non‑small cell lung cancer (NSCLC) cells, and to assess the underlying anticancer mechanisms. In PC‑9 cells, treatment with triptolide reduced cell proliferation and increased cell apoptosis and caspase‑3 and 9 activity. Triptolide treatment reduced miR‑21 expression and enhanced phosphatase and tensin homolog (PTEN) protein expression levels in the PC‑9 cells. Furthermore, the upregulation of miR‑21 expression levels suppressed the effect of triptolide on cell viability and PTEN protein expression levels in PC‑9 cells. To the best of our knowledge, the present study is the first to demonstrate that triptolide reduced the proliferation and enhanced the apoptosis of human NSCLC cells through PTEN by targeting miR-21.

Minnelide Overcomes Oxaliplatin Resistance by Downregulating the DNA Repair Pathway in Pancreatic Cancer

INTRODUCTION

Oxaliplatin is part of pancreatic cancer therapy in the FOLFIRINOX or GEMOX/XELOX regimen. DNA damage repair is one of the factors responsible for oxaliplatin resistance that eventually develops in this cancer. Triptolide/Minnelide has been shown to be effective against pancreatic cancer in preclinical trials. In this study, we evaluated the efficacy of combination of triptolide and oxaliplatin against pancreatic cancer.

METHODS

Highly aggressive pancreatic cancer cells (MIA PaCa-2 and PANC-1) were treated with oxaliplatin (0-10 μM), low-dose triptolide (50 nM), or a combination of both for 24-48 h. Cell viability, apoptosis, and DNA damage were evaluated by appropriate methods. Nucleotide excision repair pathway components were quantitated using qPCR and Western blot. Combination of low doses of Minnelide and oxaliplatin was tested in an orthotopic murine model of pancreatic cancer.

RESULTS

Proliferation of pancreatic cancer cells was markedly inhibited by combination treatment. Triptolide potentiated apoptotic cell death induced by oxaliplatin and sensitized cancer cells towards oxaliplatin-induced DNA damage by suppressing the oxaliplatin-induced DNA damage repair pathway. Combination of low doses of Minnelide and oxaliplatin inhibited tumor progression by inducing significant apoptotic cell death in these tumors.

CONCLUSIONS

Combination of low doses of Minnelide and oxaliplatin has immense potential to emerge as a novel therapeutic strategy against pancreatic cancer.

Theracurmin® efficiently inhibits the growth of human prostate and bladder cancer cells via induction of apoptotic cell death and cell cycle arrest

In the present study, we aimed to investigate the anticancer properties of Theracurmin®, a novel form of the yellow curry pigment curcumin, as well as explore the molecular mechanisms of the potential anticancer effects of Theracurmin® on human prostate cancer and bladder cancer cells in vitro. The proliferation of cancer cells was examined by using the Cell Counting Kit-8. The clonogenic growth potential was determined by clonogenic assay. Cell cycle distribution was evaluated by flow cytometry using propidium iodide staining. Western blot analysis was applied to explore the expression patterns of molecules associated with apoptotic cell death and cell cycle checkpoint. We noted that Theracurmin® and curcumin exhibited similar anticancer effects in both androgen-dependent and -independent human prostate cancer cells in a dose- and time-dependent manner. These agents reduced cell viability and clonogenic growth potential by inducing apoptosis and cell cycle disturbance in human prostate cancer cells. Theracurmin® and curcumin also exerted marked anticancer effects on human bladder cancer cells, even in cisplatin-resistant T24R2 cells, in a dose- and time-dependent manner. Moreover, Theracurmin® and curcumin treatment decreased cell viability and clonogenicity via induction of apoptotic cell death and cell cycle dysregulation in human bladder cancer cells. In conclusion, our study suggests that Theracurmin® has potential as an anticancer agent in complementary and alternative medicine for these urological cancers.

Triptolide potentiates lung cancer cells to cisplatin-induced apoptosis by selectively inhibiting the NER activity

Background

Cisplatin and many other platinum-based compounds are important anticancer drugs that are used in treating many cancer types. The development of cisplatin-resistant cancer cells, however, quickly diminishes the effectiveness of these drugs and causes treatment failure. New strategies that reverse cancer cell drug resistance phenotype or sensitize cancer cells to these drugs, therefore, need to be explored in order to improve platinum drug-based cancer treatment. Triptolide is a bioactive ingredient isolated from Tripterygium wilfordii, a Chinese herbal medicine. Triptolide binds to the TFIIH basal transcription factor and is required for both transcription and nucleotide excision repair (NER), a DNA repair pathway involved in repairing DNA damage generated by the platinum-based anticancer drugs.

Methods

Caspase-3 activation and cell growth inhibition assays were used to determine the effect of triptolide on cisplatin-induced apoptosis and cell growth in lung cancer cells. Real time PCR, immunoblotting, and expression of reef coral red protein were used to determine a mechanism through which the presence of triptolide increased cisplatin-induced apoptosis of the lung cancer cells.

Results

Our caspase-3 activation studies demonstrated that the presence of low-levels of triptolide greatly increased the cisplatin-induced apoptosis of HTB182, A549, CRL5810, and CRL5922 lung cancer cells. The results of our cell growth inhibition studies revealed that the presence of low-levels triptolide itself had little effect on cell growth but greatly enhanced cisplatin-induced cell growth inhibition in both A549 and HTB182 cells. The results of our reef coral-red protein reporter expression studies indicated that the presence of low-levels triptolide did not affect expression of the reef coral-red protein from pDsRed2-C1 plasmid but greatly inhibited expression of the reef coral-red protein from cisplatin-damaged pDsRed2-C1 plasmid DNA in A549 cells. In addition, the results of our protein phosphorylation studies indicated that the presence of low-levels triptolide caused a decrease for cisplatin-induced CHK1 phosphorylation at Ser^317/345 but an increase for cisplatin-induced ATM phosphorylation at Ser¹⁹⁸¹ in both HTB182 and A549 cells.

Conclusion

The results of our studies suggest that the presence of low-levels of triptolide potentiates lung cancer cells to cisplatin treatment by selectively inhibiting NER activity, resulting in an increase in apoptosis of the lung cancer cells.