Synergistic effect of triptolide combined with 5-fluorouracil on colon carcinoma

Targeted drug-loaded peptides induce tumor cell apoptosis and immunomodulation to increase antitumor efficacy

Immunotherapy is an emerging approach for the treatment of solid tumors. Although chemotherapy is generally considered immunosuppressive, specific chemotherapeutic agents can induce tumor immunity. In this study, we developed a targeted, acid-sensitive peptide nanoparticle (DT/Pep1) to deliver doxorubicin (DOX) and triptolide (TPL) to breast cancer cells via the enhanced permeability and retention (EPR) effect and the breast cancer-targeting effect of peptide D8. Compared with administration of the free drugs, treatment with the DT/Pep1 system increased the accumulation of DOX and TPL at the tumor site and achieved deeper penetration into the tumor tissue. In an acidic environment, DT/Pep1 transformed from spherical nanoparticles to aggregates with a high aspect ratio, which successfully extended the retention of the drugs in the tumor cells and bolstered the anticancer effect. In both in vivo and in vitro experiments, DT/Pep1 effectively blocked the cell cycle and induced apoptosis. Importantly, the DT/Pep1 system efficiently suppressed tumor development in mice bearing 4T1 tumors while simultaneously promoting immune system activation. Thus, the results of this study provide a system for breast cancer therapy and offer a novel and promising platform for peptide nanocarrier-based drug delivery.

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.

The Study of Cellular Mechanism of Triptolide in the Treatment of Cancer, Bone Loss and Cardiovascular Disease and Triptolide's Toxicity

Triptolide (TPL), the active component of Tripterygium wilfordii Hook F (Twhf) has been used to treat cancer and bone loss conditions for over two hundred years in traditional Chinese medicine (TCM). In this paper, we reviewed the specific molecular mechanisms in the treatment of cancer, bone loss and cardiovascular disease. In addition, we analyze the toxicity of TPL and collect some optimized derivatives extracted from TPL. Although positive results were obtained in most cell culture and animal studies, further studies are needed to substantiate the beneficial effects of TPL.

1H NMR-Based Metabolomics Reveals the Antitumor Mechanisms of Triptolide in BALB/c Mice Bearing CT26 Tumors

Triptolide, the main active ingredient in Tripterygium wilfordii Hook. f. (Celastraceae), has shown promising effects against a variety of tumors. However, the molecular pharmacological mechanisms explaining the action of triptolide remain unknown. In this study, the CT26 colon tumor cell line was inoculated subcutaneously into BALB/c mice, and plasma samples were subjected to ¹H NMR metabolomics analysis. The metabolic signature identified five metabolites whose levels were lower and 15 whose levels were higher in CT26 tumor-bearing mice than in normal control mice. Triptolide treatment significantly reversed the levels of nine of these metabolites, including isoleucine, glutamine, methionine, proline, 3-hydroxybutyric acid, 2-hydroxyisovalerate, 2-hydroxyisobutyrate, and low-density lipoprotein/very low-density lipoprotein. Based on the identities of these potential biomarkers, we conclude that the antitumor mechanism of triptolide might rely on correcting perturbations in branched-chain amino acid metabolism, serine/glycine/methionine biosynthesis, and ketone bodies metabolism.

Traditional Chinese medicine-combination therapies utilizing nanotechnology-based targeted delivery systems: a new strategy for antitumor treatment

Cancer is a major public health problem, and is now the world’s leading cause of death. Traditional Chinese medicine (TCM)-combination therapy is a new treatment approach and a vital therapeutic strategy for cancer, as it exhibits promising antitumor potential. Nano-targeted drug-delivery systems have remarkable advantages and allow the development of TCM-combination therapies by systematically controlling drug release and delivering drugs to solid tumors. In this review, the anticancer activity of TCM compounds is introduced. The combined use of TCM for antitumor treatment is analyzed and summarized. These combination therapies, using a single nanocarrier system, namely codelivery, are analyzed, issues that require attention are determined, and future perspectives are identified. We carried out a systematic review of >280 studies published in PubMed since 1985 (no patents involved), in order to provide a few basic considerations in terms of the design principles and management of targeted nanotechnology-based TCM-combination therapies.

Combinatorial Cytotoxic Effects of Gelam Honey and 5-Fluorouracil against Human Adenocarcinoma Colon Cancer HT-29 Cells In Vitro

Combination of natural products with chemodrugs is becoming a trend in discovering new therapeutics approach for enhancing the cancer treatment process. In the present study, we aimed to investigate the cytotoxic and apoptosis induction of Gelam honey (GH) combined with or without 5-Fluorouracil (5-FU) on HT-29 cells. The cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay to assess cytotoxicity. Morphological changes and apoptosis were determined by the inverted microscope, Annexin V-FITC, and DNA fragmentation via flow cytometric analysis, respectively. Our results demonstrate that combined treatment revealed a remarkable and concentration-dependent cytotoxic effect on HT-29 cells in comparison with GH and 5-FU alone. Flow cytometry analysis showed that early apoptosis event was more pronounced in combined treatment. In addition, compared to 5-FU alone, apoptosis of HT-29 cells treated with combinations of GH and 5-FU demonstrated increasing percentages of fragmented DNA. Our results suggest that GH has a synergistic cytotoxic effect with 5-FU in HT-29 cell lines in vitro. Although the actions of the molecular mechanisms are not yet clear, the results reveal that the combination of GH and 5-FU could have the potential as a therapeutic agent.

Triptolide inhibits Epstein-Barr nuclear antigen 1 expression by increasing sensitivity of mitochondria apoptosis of nasopharyngeal carcinoma cells

BACKGROUND

Epstein-Barr virus (EBV) is widely found in nasopharyngeal carcinoma (NPC) tissue and associated with poor prognosis of patients. EBV nuclear antigen 1 (EBNA1) is expressed in all NPC tumors and plays multiple biological roles in both virus and host cells. Triptolide is a natural product extracted from Tripterygium and shows anti-cancer activities. The goal of this work was to illustrate the anti-cancer effect of triptolide and elucidate a novel anti-apoptotic mechanism of EBNA1 in NPC cells encountered with triptolide.

METHODS

In the present study, a CCK-8 assay was used to analyze the proliferation of NPC cells treated with triptolide in a dose- and time-dependent ways. Effects of triptolide on NPC cell cycle and apoptosis were investigated by flow cytometric analysis. EBNA1 expression in mRNA and protein levels was determined by quantitative real-time PCR and Western blot, respectively.

RESULTS

Our results showed that triptolide effectively inhibited proliferation of NPC cells. Triptolide arrested NPC cell cycles in S phase and induced apoptosis through a caspase-9-dependent apoptosis pathway. Low-dose of triptolide reduced the half-life of EBNA1 and significantly decreased EBNA1 expression by promoting the process of proteasome-ubiquitin pathway. Over-expression of EBNA1, which was independent from EBV genome, effectively attenuated the apoptosis induced by triptolide. In addition, triptolide significantly inhibited proliferations of tumors induced by EBV-positive cells in vivo. Furthermore, EBNA1 were expressed in all NPC biopsies of Chinese patients.

CONCLUSIONS

In summary, our study provides the evidence that triptolide induces EBNA1 degradation and stimulates NPC apoptosis through mitochondria apoptotic pathway. In addition, EBNA1 assists NPC cells to resist triptolide-induced apoptosis through inhibiting caspase-9-dependent apoptotic pathway.

New Insights toward Colorectal Cancer Chemotherapy Using Natural Bioactive Compounds

Combination therapy consists in the simultaneous administration of a conventional chemotherapy drug (or sometimes, a radiotherapy protocol) together with one or more natural bioactives (usually from plant or fungal origin) of small molecular weight. This combination of anticancer drugs may be applied to cell cultures of tumor cells, or to an animal model for a cancer type (or its xenograft), or to a clinical trial in patients. In this review, we summarize current knowledge describing diverse synergistic effects on colorectal cancer cell cultures, animal models, and clinical trials of various natural bioactives (stilbenes, flavonoids, terpenes, curcumin, and other structural families), which may be important with respect to diminish final doses of the chemotherapy drug, although maintaining its biological effect. This is important as these approaches may help reduce side effects in patients under conventional chemotherapy. Also, these molecules may exerts their synergistic effects via different cell cycle pathways, including different ones to those responsible of resistance phenotypes: transcription factors, membrane receptors, adhesion and structural molecules, cell cycle regulatory components, and apoptosis pathways.

Codelivery of doxorubicin and triptolide with reduction-sensitive lipid-polymer hybrid nanoparticles for in vitro and in vivo synergistic cancer treatment

Codelivery is a promising strategy to overcome the limitations of single chemotherapeutic agents in cancer treatment. Despite progress, codelivery of two or more different functional drugs to increase anticancer efficiency still remains a challenge. Here, reduction-sensitive lipid–polymer hybrid nanoparticles (LPNPs) drug delivery system composed of monomethoxy-poly(ethylene glycol)-S-S-hexadecyl (mPEG-S-S-C₁₆), soybean lecithin, and poly(D,L-lactide-co-glycolide) (PLGA) was used for codelivery of doxorubicin (DOX) and a Chinese herb extract triptolide (TPL). Hydrophobic DOX and TPL could be successfully loaded in LPNPs by self-assembly. More importantly, drug release and cellular uptake experiments demonstrated that the two drugs were reduction sensitive, released simultaneously from LPNPs, and taken up effectively by the tumor cells. DOX/TPL-coloaded LPNPs (DOX/TPL-LPNPs) exhibited a high level of synergistic activation with low combination index (CI) in vitro and in vivo. Moreover, the highest synergistic therapeutic effect was achieved at the ratio of 1:0.2 DOX/TPL. Further experiments showed that TPL enhanced the uptake of DOX by human oral cavity squamous cell carcinoma cells (KB cells). Overall, DOX/TPL-coencapsulated reduction-sensitive nanoparticles will be a promising strategy for cancer treatment.

Triptolide Combined with Radiotherapy for the Treatment of Nasopharyngeal Carcinoma via NF-κB-Related Mechanism

Advanced nasopharyngeal carcinoma (NPC) has a poor prognosis because of the lack of an effective treatment. Here we explored the efficiency and the molecular mechanisms of combined treatment with triptolide and ionizing radiation for treating NPC. Human nasopharyngeal carcinoma (CNE) cells were treated with triptolide, ionizing radiation, or triptolide plus ionizing radiation in vitro. Tumor potency was examined in an in vivo CNE cell xenograft mouse model, which was treated as above. Our results demonstrated that triptolide caused a significant reduction in cell growth and colony number, and induced a marked apoptosis that was further enhanced with increasing doses of ionizing radiation. Combination treatment synergistically reduced tumor weight and volume without obvious toxicity. Western blot analysis in vitro and in vivo showed that triptolide induced apoptotic protein Bax expression and inhibited phosph-NF-κB p65, Bcl-2 and VEGF proteins without affecting other NF-κB related protein expression. In conclusion, our findings revealed that triptolide plus ionizing radiation had synergistic anti-tumor and anti-angiogenesis effects in NPC via down-regulating NF-κB p65 phosphorylation. The combination therapy may provide novel mechanism insights into inhibit NPC.

Chinese Herbal Medicine and Fluorouracil-Based Chemotherapy for Colorectal Cancer: A Quality-Adjusted Meta-Analysis of Randomized Controlled Trials

Background Chinese herbal medicines reportedly increase efficacy and minimize toxicity of chemotherapy; however, little attention has been paid to how poor study quality can bias outcomes. Methods We systematically searched MEDLINE, TCMLARS, EMBASE, and Cochrane Library for randomized controlled trials of Chinese herbal medicines combined with fluorouracil-based chemotherapy compared with the same chemotherapy alone. We screened for eligibility, extracted data, and pooled data with random-effects meta-analysis. Outcome measures were survival, toxicity, tumor response, performance status, quality of life, and Cochrane Risk of Bias (ROB) criteria to critically evaluate the quality of reporting in the randomized trials included in the meta-analysis. Results We found 36 potentially eligible studies, with only 3 (those with low ROB) qualifying for meta-analysis. Two reported chemotherapy-related diarrhea reduced by 57% (relative risk [RR] = 0.43; 95% CI = 0.19-1.01; I(2) test for variation in RR due to heterogeneity = 0.0%), with nonsignificant results. Two reported white blood cell toxicity reduced by 66% (RR = 0.34; 95% CI = 0.16-0.72; I(2) test for variation in RR due to heterogeneity = 0.0%), with statistically significant results. Stratifying analysis by studies with high versus low ROB, we found substantial overestimation of benefit: Studies with high ROB overestimated by nearly 2-fold reduction of platelet toxicity by Chinese herbal medicines (RR = 0.35, 95% CI = 0.15-0.84 vs RR = 0.65, 95% CI = 0.11-3.92). Studies with high ROB overestimated by nearly 2-fold reduction of vomiting toxicity (RR = 0.45, 95% CI = 0.33-0.61 vs RR = 0.87, 95% CI = 0.48-1.58). And, studies with high ROB overestimated by 21% the reduction in diarrhea toxicity (RR = 0.34, 95% CI = 0.20-0.58 vs RR = 0.43, 95% CI = 0.19-1.01). Studies with high ROB also overestimated by 16% improvement in tumor response (RR = 1.39, 95% CI = 1.18-1.63 vs RR = 1.20; 95% CI = 0.81-1.79). Not accounting for ROB would have exaggerated evidence of benefit and failed to detect nonsignificance of results. Conclusions In the present analysis, involving 36 studies, 2593 patients, 20 outcomes, 36 medical institutions, and 271 named research authors, 92% of the data points were from studies at high ROB. Given the poor quality of the data in studies identified, it cannot be concluded whether combining Chinese herbs with chemotherapy reduces toxicity of chemotherapy.

Suppressive effect of sinomenine combined with 5-fluorouracil on colon carcinoma cell growth

It is reported that sinomenine (SIN) and 5-fluorouracil (5-FU) both are effective for colon cancer, but their cooperative suppressive effects and toxicity remain to be clarified in detail. This study aimed to determine suppressive effects and toxicity of sinomenine (SIN) plus 5-fluorouracil (5-FU) on LoVo colon carcinoma cells in vitro and in vivo. CCK-8, Hoechst 33258 staining and an annexin V-FITC/PI apoptosis kit were used to detect suppressive effects. Western blotting was applied to investigate the essential mechanism underlying SIN and 5-FU-induced apoptosis. SIN or 5-FU or both were injected into nude mice, and then suppressive effects and side effects were observed. SIN plus 5-FU apparently inhibited the proliferation of LoVo cells and induced apoptosis. Moreover the united effects were stronger than individually (p<0.05). The results of annexin V-FITC /PI staining and Hoechst 33258 staining showed that the percentage of apoptotic cells induced by SIN and 5-FU combined or alone was significantly higher than the control group (p<0.05). Expression of Bax and Bcl-2 was up-regulated and down-regulated respectively. SIN or 5-FU significantly inhibited effects on the volume of tumour xenografts and their combined suppressive effects were stronger (p<0.05). No obvious side effects were observed. It was apparent that the united effects of SIN and 5-FU on the growth of colorectal carcinoma LoVo cells in vitro and in vivo were superior to those using them individually, and it did not markedly increase the side effects of chemotherapy.

Piper betle leaf extract enhances the cytotoxicity effect of 5-fluorouracil in inhibiting the growth of HT29 and HCT116 colon cancer cells

OBJECTIVE

The combination effect of Piper betle (PB) and 5-fluorouracil (5-FU) in enhancing the cytotoxic potential of 5-FU in inhibiting the growth of colon cancer cells was investigated.

METHODS

HT29 and HCT116 cells were subjected to 5-FU or PB treatment. 5-FU and PB were then combined and their effects on both cell lines were observed after 24 h of treatment. PB-5-FU interaction was elucidated by isobologram analysis. Apoptosis features of the treated cells were revealed by annexin V/PI stain. High-performance liquid chromatography (HPLC) was performed to exclude any possible chemical interaction between the compounds.

RESULTS

In the presence of PB extract, the cytotoxicity of 5-FU was observed at a lower dose (IC50 12.5 µmol/L) and a shorter time (24 h) in both cell lines. Both cell lines treated with 5-FU or PB alone induced a greater apoptosis effect compared with the combination treatment. Isobologram analysis indicated that PB and 5-FU interacted synergistically and antagonistically in inhibiting the growth of HT29 and HCT116 cells, respectively.

CONCLUSIONS

In the presence of PB, a lower dosage of 5-FU is required to achieve the maximum drug effect in inhibiting the growth of HT29 cells. However, PB did not significantly reduce 5-FU dosage in HCT116 cells. Our result showed that this interaction may not solely contribute to the apoptosis pathway.

Combination treatment with triptolide and hydroxycamptothecin synergistically enhances apoptosis in A549 lung adenocarcinoma cells through PP2A-regulated ERK, p38 MAPKs and Akt signaling pathways

Lung cancer is the leading cause of cancer death worldwide. Recently, two plant-derived drugs triptolide (TP) and hydroxycamptothecin (HCPT) both have shown broad-spectrum anticancer activities. Our previous study documented that combination treatment with these two drugs acted more effectively than mono-therapy, however, the molecular basis underlying the synergistic cytotoxicity remains poorly understood. In this study, we aimed to clarify the molecular mechanism of TP/HCPT anticancer effect in A549 lung adenocarcinoma cells, by investigating the involvement of phosphatase 2A (PP2A) and PP2A-regulated mitogen-activated protein kinases (MAPKs) and Akt signaling pathways. The results showed that TP and HCPT synergistically exerted cytotoxicity in the growth of A549 cells. Combinatorial TP/HCPT treatment significantly enhanced the activation of caspase-3 and -9, Bax/Bcl-2 ratio, release of cytochrome c from mitochondrial and subsequent apoptosis. While the Akt survival pathway was inhibited, ERK and p38 MAPKs were dramatically activated. Furthermore, the activity of PP2A was significantly augmented. Regulation of p38, ERK and Akt by PP2A was demonstrated, by using a specific PP2A inhibitor okadaic acid (OA). Finally, pharmacological inhibitors OA, SB203580, SP600125 and PD98059 confirm the role of PP2A and its substrates ERK, p38 MAPK and Akt in mediating TP/HCPT-induced apoptosis. Taken together, this study provides the first evidence for a synergistic TP/HCPT anti-cancer activity in A549 cells and also supports a critical role of PP2A and PP2A-regulated signaling pathways, providing new insight into the mode of action of TP/HCPT in cancer therapy.

Triptolide: progress on research in pharmacodynamics and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Tripterygium wilfordii Hook. f. (Tripterygium wilfordii), also known as Huangteng and gelsemium elegan, is a traditional Chinese medicine that has been marketed in China as Tripterygium wilfordii glycoside tablets. Triptolide (TP), an active component in Tripterygium wilfordii extracts, has been used to treat various diseases, including lupus, cancer, rheumatoid arthritis and nephritic syndrome. This review summarizes recent developments in the research on the pharmacodynamics, pharmacokinetics, pharmacy and toxicology of TP, with a focus on its novel mechanism of reducing toxicity. This review provides insight for future studies on traditional Chinese medicine, a field that is both historically and currently important.

MATERIALS AND METHODS

We included studies published primarily within the last five years that were available in online academic databases (e.g., PubMed, Google Scholar, CNKI, SciFinder and Web of Science).

RESULTS

TP has a long history of use in China because it displays multiple pharmacological activities, including anti-rheumatism, anti-inflammatory, anti-tumor and neuroprotective properties. It has been widely used for the treatment of various diseases, such as rheumatoid arthritis, nephritic syndrome, lupus, Behcet׳s disease and central nervous system diseases. Recently, numerous breakthroughs have been made in our understanding of the pharmacological efficacy of TP. Although TP has been marketed as a traditional Chinese medicine, its multi-organ toxicity prevents it from being widely used in clinical practice.

CONCLUSIONS

Triptolide, a biologically active natural product extracted from the root of Tripterygium wilfordii, has shown promising pharmacological effects, particularly as an anti-tumor agent. Currently, in anti-cancer research, more effort should be devoted to investigating effective anti-tumor targets and confirming the anti-tumor spectrum and clinical indications of novel anti-tumor pro-drugs. To apply TP appropriately, with high efficacy and low toxicity, the safety and non-toxic dose range for specific target organs and diseases should be determined, the altered pathways and mechanisms of exposure need to be clarified, and an early warning system for toxicity needs to be established. With further in-depth study of the efficacy and toxicity of TP, we believe that TP will become a promising multi-use drug with improved clinical efficacy and safety in the future.

Gelam honey and ginger potentiate the anti cancer effect of 5-FU against HCT 116 colorectal cancer cells

The development of chemopreventive approaches using a concoction of phytochemicals is potentially viable for combating many types of cancer including colon carcinogenesis. This study evaluated the anti-proliferative effects of ginger and Gelam honey and its efficacy in enhancing the anti-cancer effects of 5-FU (5-fluorouracil) against a colorectal cancer cell line, HCT 116. Cell viability was measured via MTS (3-(4,5-dimethylthiazol-2- yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphenyl)-2H-tetrazolium) assay showing ginger inhibiting the growth of HCT 116 cells more potently (IC50 of 3mg/mL) in comparison to Gelam honey (IC50 of 75 mg/mL). Combined treatment of the two compounds (3mg/mL ginger+75 mg/mL Gelam honey) synergistically lowered the IC50 of Gelam honey to 22 mg/mL. Combination with 35 mg/mL Gelam honey markedly enhanced 5-FU inhibiting effects on the growth of HCT 116 cells. Subsequent analysis on the induction of cellular apoptosis suggested that individual treatment of ginger and Gelam honey produced higher apoptosis than 5-FU alone. In addition, treatment with the combination of two natural compounds increased the apoptotic rate of HCT 116 cells dose- dependently while treatment of either ginger or Gelam honey combined with 5-FU only showed modest changes. Combination index analysis showed the combination effect of both natural compounds to be synergistic in their inhibitory action against HCT 116 colon cancer cells (CI 0.96 < 1). In conclusion, combined treatment of Gelam honey and ginger extract could potentially enhance the chemotherapeutic effect of 5-FU against colorectal cancer.

Minnelide: a novel therapeutic that promotes apoptosis in non-small cell lung carcinoma in vivo

BACKGROUND

Minnelide, a pro-drug of triptolide, has recently emerged as a potent anticancer agent. The precise mechanisms of its cytotoxic effects remain unclear.

METHODS

Cell viability was studied using CCK8 assay. Cell proliferation was measured real-time on cultured cells using Electric Cell Substrate Impedence Sensing (ECIS). Apoptosis was assayed by Caspase activity on cultured lung cancer cells and TUNEL staining on tissue sections. Expression of pro-survival and anti-apoptotic genes (HSP70, BIRC5, BIRC4, BIRC2, UACA, APAF-1) was estimated by qRTPCR. Effect of Minnelide on proliferative cells in the tissue was estimated by Ki-67 staining of animal tissue sections.

RESULTS

In this study, we investigated in vitro and in vivo antitumor effects of triptolide/Minnelide in non-small cell lung carcinoma (NSCLC). Triptolide/Minnelide exhibited anti-proliferative effects and induced apoptosis in NSCLC cell lines and NSCLC mouse models. Triptolide/Minnelide significantly down-regulated the expression of pro-survival and anti-apoptotic genes (HSP70, BIRC5, BIRC4, BIRC2, UACA) and up-regulated pro-apoptotic APAF-1 gene, in part, via attenuating the NF-κB signaling activity.

CONCLUSION

In conclusion, our results provide supporting mechanistic evidence for Minnelide as a potential in NSCLC.

Herbal compound triptolide synergistically enhanced antitumor activity of amino-terminal fragment of urokinase

Background

Urokinase (uPA) and its receptor (uPAR) play an important role in tumour growth and metastasis, and overexpression of these molecules is strongly correlated with poor prognosis in a variety of malignant tumours. Targeting the excessive activation of this system as well as the proliferation of the tumour vascular endothelial cell would be expected to prevent tumour neovasculature and halt tumour development. The amino terminal fragment (ATF) of urokinase has been confirmed effective to inhibit the proliferation, migration and invasiveness of cancer cells via interrupting the interaction of uPA and uPAR. Triptolide (TPL) is a purified diterpenoid isolated from the Chinese herb Tripterygium wilfordii Hook F that has shown antitumor activities in various cancer cell types. However, its therapeutic application is limited by its toxicity in normal tissues and complications caused in patients. In this study, we attempted to investigate the synergistic anticancer activity of TPL and ATF in various solid tumour cells.

Methods

Using in vitro and in vivo experiments, we investigated the combined effect of TPL and ATF at a low dosage on cell proliferation, cell apoptosis, cell cycle distribution, cell migration, signalling pathways, xenograft tumour growth and angiogenesis.

Results

Our data showed that the sensitivity of a combined therapy using TPL and ATF was higher than that of TPL or ATF alone. Suppression of NF-κB transcriptional activity, activation of caspase-9/caspase-3, cell cycle arrest, and inhibition of uPAR-mediated signalling pathway contributed to the synergistic effects of this combination therapy. Furthermore, using a mouse xenograft model, we demonstrated that the combined treatment completely suppressed tumour growth by inhibiting angiogenesis as compared with ATF or TPL treatment alone.

Conclusions

Our study suggests that lower concentration of ATF and TPL used in combination may produce a synergistic anticancer efficacy that warrants further investigation for its potential clinical applications.

Triptolide modulates the sensitivity of K562/A02 cells to adriamycin by regulating miR-21 expression

CONTEXT

Multidrug-resistance is a serious obstacle encountered in leukemia treatment. Recent studies have shown microRNA-21 (miR-21) is overexpressed in several types of cancer and contributes to tumor resistance to chemotherapy. In our previous studies, we found triptolide (TPL) could enhance adriamycin-induced cytotoxicity and apoptosis in K562/A02 cells.

OBJECTIVE

In the present study, we investigated the mechanism of TPL on the sensitivity of K562/A02 cells to adriamycin.

MATERIALS AND METHODS

Cell viability was assessed by methyl thiazolyl tetrazolium (MTT) assay. Expression of mature miR-21 was determined by SYBER green PCR. The miR-21 mimics and inhibitors were chemically synthesized and transfected into K562 cells or K562/A02 cells. PTEN protein levels was determined by western blots. PTEN promoter activity was measured by luciferase assays.

RESULTS

TPL (5 nmol/L) increased the sensitivity of K562/A02 to adriamycin. When adriamycin was combined with 5 nmol/L TPL, the mean apoptotic population of K562/A02 cells was increased from 4.3 to 18.5%, respectively. K562/A02 cells showed a significant reduction in miR-21 and phosphatase and tensin homolog deleted on chromosome ten (PTEN) expressions after TPL treatment. K562/A02 cells that were transfected with the miR-21 inhibitor had a significantly higher PTEN protein level than the control. K562 cells that were pre-treated with PTEN siRNA had increased survival rate compared to the control group.

DISCUSSION AND CONCLUSION

Our findings indicated that triptolide modulates the sensitivity of K562/A02 cells to adriamycin by regulating miR-21 expression. Triptolide inhibited miR-21 expression and enhanced PTEN levels in K562/A02 cells.

Triptolide: structural modifications, structure-activity relationships, bioactivities, clinical development and mechanisms

Triptolide, a principal bioactive ingredient of Tripterygium wilfordii Hook F, has attracted extensive exploration due to its unique structure of a diterpenoid triepoxide and multiple biological activities. This review will focus on the structural modifications, structure-activity relationships, pharmacology, and clinical development of triptolide in the last forty years.

Modulation of P-glycoprotein expression by triptolide in adriamycin-resistant K562/A02 cells

Multidrug resistance is a serious obstacle encountered in leukemia treatment. Previous studies have found drug resistance in human leukemia is mainly associated with overexpression of the multidrug resistance gene 1 (MDR1). The aim of the present study was to investigate the modulation of P-glycoprotein expression by triptolide in adriamycin-resistant K562/A02 cells. The reverse effects of triptolide on drug resistance in K562/A02 cells were assessed by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyl-tetrazolium bromide (MTT) assay. The percentage of apoptotic cells was obtained from annexin V/fluorescein isothiocyanate (FITC) and propridium iodide (PI) double-staining. The effects of triptolide on P-glycoprotein activity were evaluated by measuring intracellular adriamycin accumulation. The expression of P-glycoprotein was determined by flow cytometry. A luciferase reporter gene assay was used to detect the transcriptional activity of the MDR1 promoter. Results revealed that triptolide decreased the degree of resistance of K562/A02 cells, and significantly inhibited P-glycoprotein expression and drug-transport function, and increased the accumulation of adriamycin in K562/A02 cells as measured by flow cytometry. A luciferase reporter gene assay demonstrated that triptolide was capable of inhibiting the transcriptional activity of the MDR1 promoter. Triptolide may effectively reverse the adriamycin resistance in K562/A02 cells via modulation of the P-glycoprotein expression and by increasing intracellular adriamycin accumulation.

Anti-cancer natural products isolated from chinese medicinal herbs

In recent years, a number of natural products isolated from Chinese herbs have been found to inhibit proliferation, induce apoptosis, suppress angiogenesis, retard metastasis and enhance chemotherapy, exhibiting anti-cancer potential both in vitro and in vivo. This article summarizes recent advances in in vitro and in vivo research on the anti-cancer effects and related mechanisms of some promising natural products. These natural products are also reviewed for their therapeutic potentials, including flavonoids (gambogic acid, curcumin, wogonin and silibinin), alkaloids (berberine), terpenes (artemisinin, β-elemene, oridonin, triptolide, and ursolic acid), quinones (shikonin and emodin) and saponins (ginsenoside Rg3), which are isolated from Chinese medicinal herbs. In particular, the discovery of the new use of artemisinin derivatives as excellent anti-cancer drugs is also reviewed.

Anti-cancer natural products isolated from chinese medicinal herbs

In recent years, a number of natural products isolated from Chinese herbs have been found to inhibit proliferation, induce apoptosis, suppress angiogenesis, retard metastasis and enhance chemotherapy, exhibiting anti-cancer potential both in vitro and in vivo. This article summarizes recent advances in in vitro and in vivo research on the anti-cancer effects and related mechanisms of some promising natural products. These natural products are also reviewed for their therapeutic potentials, including flavonoids (gambogic acid, curcumin, wogonin and silibinin), alkaloids (berberine), terpenes (artemisinin, β-elemene, oridonin, triptolide, and ursolic acid), quinones (shikonin and emodin) and saponins (ginsenoside Rg₃), which are isolated from Chinese medicinal herbs. In particular, the discovery of the new use of artemisinin derivatives as excellent anti-cancer drugs is also reviewed.

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

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

Quercetin enhances 5-fluorouracil-induced apoptosis in MSI colorectal cancer cells through p53 modulation

PURPOSE

Colorectal tumors (CRC) with microsatellite instability (MSI) show resistance to chemotherapy with 5-fluorouracil (5-FU), the most widely used pharmacological drug for CRC treatment. The aims of this study were to test the ability of quercetin (Q) and luteolin (L) to increase the sensitivity of MSI CRC cells to 5-FU and characterize the dependence of the effects on cells' p53 status.

METHODS

Two MSI human CRC-derived cell lines were used: CO115 wild type (wt) for p53 and HCT15 that harbors a p53 mutation. Apoptosis induction in these cells by 5-FU, Q and L alone, and in combinations was evaluated by TUNEL and western blot. The dependence of the effects on p53 was confirmed by small interference RNA (siRNA) in CO115 cells and in MSI HCT116 wt and p53 knockout cells.

RESULTS

CO115 p53-wt cells are more sensitive to 5-FU than the p53-mutated HCT15. The combination treatment of 5-FU with L and Q increased apoptosis with a significant effect for Q in CO115. Both flavonoids increased p53 expression in both cell lines, an effect particularly remarkable for Q. The significant apoptotic enhancement in CO115 incubated with Q plus 5-FU involved the activation of the apoptotic mitochondrial pathway. Importantly, knockdown of p53 by siRNA in CO115 cells and p53 knockout in HCT116 cells totally abrogated apoptosis induction, demonstrating the dependence of the effect on p53 modulation by Q.

CONCLUSION

This study suggests the potential applicability of these phytochemicals for enhancement 5-FU efficiency in MSI CRC therapy, especially Q in p53 wt tumors.

Triptolide and its expanding multiple pharmacological functions

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

The synergistic effect of recombinant human endostatin (YH-16) combined with oxaliplatin on human colorectal carcinoma

This study was designed to investigate the effect of recombinant human endostatin (YH-16) combined with oxaliplatin (L-OHP) on the growth of orthotopically-implanted human colorectal carcinoma in nude mice. Tumour volumes and weights were measured after therapy. Tumour cell morphology was observed by light and electron microscopy. Apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling (TUNEL) assay, and vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) were determined by immunohistochemical staining. Tumour volumes in all treatment groups were significantly reduced compared with controls. YH-16 and L-OHP either alone or in combination caused tumour cell apoptosis, except in the YH-16 low-dose group. MVD was strongly inhibited in the treatment groups compared with the controls, although only YH-16 combined with L-OHP or L-OHP alone decreased VEGF expression. No obvious change in side-effects occurred. In conclusion, YH-16 combined with L-OHP inhibited growth and induced apoptosis in orthotopically-transplanted human colorectal carcinoma in nude mice without increasing side-effects.

Expression and functional research of TLR4 in human colon carcinoma

INTRODUCTION

To verify whether human colon carcinoma cells can express Toll-like receptor 4 (TLR4) and investigate the biological function of TLR4 on human colon carcinoma cells.

METHODS

Human colon carcinoma cells SW480 was cultured with RPMI 1640 medium. The expression of TLR4 was analyzed by reverse transcription polymerase chain reaction and quantified by flow cytometry. Cell proliferation was evaluated by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide assay. The production of transforming growth factor-beta, vascular endothelial growth factor, and interleukin-8 induced by lipopolysaccharide (LPS)-the TLR4 ligand was tested by enzyme-linked immunosorbent assay. Whether mitogen-associated protein kinases and nuclear factor-kappaB (NF-kappaB) proteins were activated was analyzed by Western blot. Apoptosis was analyzed by Annenxin V/PI staining.

RESULTS

TLR4 is expressed on SW480 cells. LPS could not affect TLR4 expression and the proliferation of SW480 cells. LPS increased the phosphorylation of ERK1/2 and P38 and activated NF-kappaB. LPS promoted the production of vascular endothelial growth factor, transforming growth factor-beta, and interleukin-8. In addition, LPS induced resistance of SW480 cells to tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis. Furthermore, NF-kappaB activation was necessary for apoptosis resistance of SW480 cells induced by LPS.

CONCLUSION

TLR4 is expressed on human colon carcinoma cells and functionally active. It may play important roles in promoting immune escape of human colon carcinoma cells by inducing immunosuppressive factors and apoptosis resistance.

Enhanced 5-fluorouracil cytotoxicity in high cyclooxygenase-2 expressing colorectal cancer cells and xenografts induced by non-steroidal anti-inflammatory drugs via downregulation of dihydropyrimidine dehydrogenase

PURPOSE

To prove that 5-FU cytotoxicity could be increased by combination with low-dose non-steroidal anti-inflammatory drugs (NSAIDs) (indomethacin or NS-398) in high cyclooxygenase-2- (COX-2) expressing cells and xenografts through the modulation of dihydropyrimidine dehydrogenase (DPD) mRNA expression and/or enzyme activity.

METHODS

HT-29 cells were grown on collagen IV coated plates (HT-29-C). The antiproliferative effect of 5-fluorouracil (5-FU) +/- NSAIDs was examined on non-COX-2 expressing HT-29 and COX-2-expressing HT-29-C cells by sulphorhodamine B assay. The COX-2 and DPD expressions were visualized by immunofluorescent staining, and prostaglandin E(2) levels were measured by ELISA kit. The HT-29 xenograft was established in SCID mice and treated with 5-FU +/- NSAIDs for 5 days. The tumor volume, enzyme activity, and DPD mRNA expression were investigated by caliper, radioenzymatic method, and real-time RT-PCR, respectively. The drug interaction was calculated for both combinations (5-FU + indomethacin and 5-FU + NS-398).

RESULTS

Collagen IV up-regulated significantly the COX-2 and DPD mRNA, and protein expressions, and also their enzyme activities in HT-29 cells. NSAIDs enhanced in a synergistic manner the cytotoxic effect of 5-FU treatment both in vitro and in vivo. Downregulation of DPD was observed after 5-FU monotherapy, but the combined effect of NSAIDs and 5-FU on DPD mRNA expression, and enzyme activity was superior to the effect of 5-FU alone.

CONCLUSIONS

Since 5-FU + NSAID treatment can alter the DPD enzyme activity resulting in an enhanced cytotoxic effect, further studies in clinical practice are warranted.

Triptolide exerts anti-tumor effect on oral cancer and KB cells in vitro and in vivo

Triptolide (TPL), a diterpenoid triepoxide purified from the Chinese herb Tripterygium wilfordii Hook F, has been reported to potentiate the anti-tumor effect in various cancer cells. However, the effect of TPL on oral cancers is not yet evaluated. Herein we first demonstrate that TPL induces prominent growth inhibition and apoptosis in two oral cancer cell lines, SCC25 and OEC-M1 and in KB cells. Our results indicate that TPL induces a dose-dependent apoptosis of these cells at nanomolar concentration. Apoptosis signalings are both activated through time upon TPL treatment detected by elevated caspase-3, 8, 9 activities. In xenograft tumor mouse model, TPL injection successfully inhibits the tumor growth via apoptosis induction which was demonstrated by TUNEL assay. These results demonstrate that TPL exerts anti-tumor effect on oral cancer and KB cells and suggest further the potential of TPL combining with other chemotherapeutic agents or radiotherapy for advanced oral cancer.

Triptolide and management of systemic malignancies besides pancreatic carcinomas

The recent article by Zhou et al was highly interesting and thought provoking. The authors have clearly shown that triptolide administration is associated with up-regulation of the Bax gene, resulting in an attenuating effect on cell growth in gastrointestinal malignancies such as pancreatic carcinomas. The article by Zhou et al is all the more important because it highlights the rapidly increasing role of triplodide in the management of systemic malignancies. For instance, triptolide acts on the PI3K/Akt/NF-κB pathway, thereby enhancing apoptosis secondary to the administration of bortezomib in multiple myeloma cells. Similar synergisms are seen when triptolide is administered along with 5-fluoruracil for the management of colonic carcinomas. Similarly, triptolide causes down-regulation of the Bcl-2 gene, resulting in control of cell growth in tumors, such as glioblastoma multiformes.