Reversal of P-glycoprotein-mediated multidrug resistance of cancer cells by five schizandrins isolated from the Chinese herb Fructus Schizandrae

In Silico and In Vitro Identification of P-Glycoprotein Inhibitors from a Library of 375 Phytochemicals

Cancer therapy with clinically established anticancer drugs is frequently hampered by the development of drug resistance of tumors and severe side effects in normal organs and tissues. The demand for powerful, but less toxic, drugs is high. Phytochemicals represent an important reservoir for drug development and frequently exert less toxicity than synthetic drugs. Bioinformatics can accelerate and simplify the highly complex, time-consuming, and expensive drug development process. Here, we analyzed 375 phytochemicals using virtual screenings, molecular docking, and in silico toxicity predictions. Based on these in silico studies, six candidate compounds were further investigated in vitro. Resazurin assays were performed to determine the growth-inhibitory effects towards wild-type CCRF-CEM leukemia cells and their multidrug-resistant, P-glycoprotein (P-gp)-overexpressing subline, CEM/ADR5000. Flow cytometry was used to measure the potential to measure P-gp-mediated doxorubicin transport. Bidwillon A, neobavaisoflavone, coptisine, and z-guggulsterone all showed growth-inhibitory effects and moderate P-gp inhibition, whereas miltirone and chamazulene strongly inhibited tumor cell growth and strongly increased intracellular doxorubicin uptake. Bidwillon A and miltirone were selected for molecular docking to wildtype and mutated P-gp forms in closed and open conformations. The P-gp homology models harbored clinically relevant mutations, i.e., six single missense mutations (F336Y, A718C, Q725A, F728A, M949C, Y953C), three double mutations (Y310A-F728A; F343C-V982C; Y953A-F978A), or one quadruple mutation (Y307C-F728A-Y953A-F978A). The mutants did not show major differences in binding energies compared to wildtypes. Closed P-gp forms generally showed higher binding affinities than open ones. Closed conformations might stabilize the binding, thereby leading to higher binding affinities, while open conformations may favor the release of compounds into the extracellular space. In conclusion, this study described the capability of selected phytochemicals to overcome multidrug resistance.

Schisandra chinensis (Turcz.) Baill. Protects against DSS-induced colitis in mice: Involvement of TLR4/NF-κB/NLRP3 inflammasome pathway and gut microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

the fruit of Schisandra chinensis (Turcz.) Baill. (SC) is an important traditional Chinese herbal medicine, which has been widely used in traditional Chinese medicine (TCM) for treating intestinal diseases. It is also traditionally used as health product and medicine in Russia and other countries. However, the effect of SC ethanol extract on anti-ulcerative colitis (UC) has not been systematically studied yet.

AIM OF THE STUDY

We investigated the protective effects and underlying action mechanisms of SC extract (SCE) for UC treatment.

MATERIALS AND METHODS

An animal model of UC induced by dextran sulfate sodium (DSS) was established. After oral administration of SCE, the Disease Activity Index (DAI) was calculated, the length of colon measured, levels of proinflammatory factors determined, and histopathology carried out to assess the therapeutic efficacy of SCE on UC. The effects of SCE on the toll-like receptor 4/nuclear factor-kappa B/nucleotide-binding and oligomerization domain-like receptor family pyrin domain containing 3 inflammasome (TLR4/NF-κB/NLRP3 inflammasome) signaling pathway were evaluated by western blotting. High-throughput sequencing was done to reveal the effect of SCE on the change of the gut microbiota (GM) in mice with DSS-induced colitis.

RESULTS

SCE significantly reduced the DAI score, restored colon-length shortening, and ameliorated colonic histopathologic injury in mice with DSS-induced colitis. SCE inhibited the inflammatory response by regulating the TLR4/NF-κB/NLRP3 inflammasome pathway in mice with UC. SCE also maintained gut barrier function by increasing the levels of zonula occludens (ZO)-1 and occludin. 16S rRNA sequencing showed that SCE could reverse the GM imbalance caused by UC.

CONCLUSIONS

SCE can ameliorate DSS-induced colitis, and that its effects might be associated with suppression of the TLR4/NF-κB/NLRP3 inflammasome pathway and GM regulation, which may provide significant supports for the development of potential candidates for UC treatment.

Schizandrin A enhances killing effect of oxaliplatin on colorectal cancer cells

BACKGROUND

Schizandrin A (SchA) has anticancer and multidrug resistance-reversing effects in a variety of tumors, but its effect on oxaliplatin (L-OHP) in colorectal cancer cells is not clear.

AIM

To investigate whether SchA can enhance the killing effect of L-OHP on colorectal cancer cells, and to analyze the possible mechanism involved.

METHODS

Colorectal cancer cells were divided into control group, SchA treatment group, L-OHP treatment group, and SchA + L-OHP treatment group. Cell viability was detected by MTT assay. Cell apoptosis was detected by flow cytometry. The contents of reactive oxygen species (ROS) in cells was detected using a ROS probe. Mitochondrial membrane potential was evaluated by using the 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachloroimidacarbocyanine iodide (JC-1) probe. Western blot was used to detect the expression of B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), cytochrome c (Cyt c), and cleaved cysteine proteinase-3 (caspase-3) in the cells.

RESULTS

Compared with the L-OHP treatment group, the viability of colorectal cancer cells in the SchA + L-OHP treatment group was significantly decreased, while apoptosis was significantly increased. SchA could enhance ROS accumulation, Bax and cleaved caspase-3 expression, and mitochondrial Cyt c release, and decrease Bcl-2 expression in colorectal cancer cells induced by L-OHP.

CONCLUSION

SchA enhances the killing effect of L-OHP on colorectal cancer cells, and the mechanism may be related to the enhancement of intracellular ROS accumulation and the expression of apoptosis-related proteins.

Schizandrin A can inhibit non‑small cell lung cancer cell proliferation by inducing cell cycle arrest, apoptosis and autophagy

Schizandrin A (SchA) can be extracted from the vine plant Schisandra chinensis and has been reported to confer various biologically active properties. However, its potential biological effects on non‑small cell lung cancer (NSCLC) remain unknown. Therefore, the present study aims to address this issue. NSCLC and normal lung epithelial cell lines were first treated with SchA. Cell viability and proliferation were measured using CellTiter‑Glo Assay and colony formation assays, respectively. PI staining was used to measure cell cycle distribution. Cell cycle‑related proteins p53, p21, cyclin D1, CDK4, CDK6, cyclin E1, cyclin E2, CDK2 and DNA damage‑related protein SOX4 were detected by western blot analysis. Annexin V‑FITC/PI staining, DNA electrophoresis and Hoechst 33342/PI dual staining were used to detect apoptosis. JC‑1 and DCFH‑DA fluorescent dyes were used to measure the mitochondrial membrane potential and reactive oxygen species concentrations, respectively. Apoptosis‑related proteins caspase‑3, cleaved caspase‑3, poly(ADP‑ribose) polymerase (PARP), cleaved PARP, BimEL, BimL, BimS, Bcl2, Bax, caspase‑9 and cleaved caspas‑9 were measured by western blot analysis. Dansylcadaverine was used to detect the presence of the acidic lysosomal vesicles. The expression levels of the autophagy‑related proteins LC3‑I/II, p62/SQSTM and AMPKα activation were measured using western blot analysis. In addition, the autophagy inhibitor 3‑methyladenine was used to inhibit autophagy. SchA treatment was found to reduce NSCLC cell viability whilst inhibiting cell proliferation. Low concentrations of SchA (10‑20 µM) mainly induced G₁/S‑phase cell cycle arrest. By contrast, as the concentration of SchA used increases (20‑50 µM), cells underwent apoptosis and G₂/M‑phase cell cycle a13rrest. As the treatment concentration of SchA increased from 0 to 50 µM, the expression of p53 and SOX4 protein also concomitantly increased, but the expression of p21 protein was increased by 10 µM SchA and decreased by higher concentrations (20‑50 µM). In addition, the mRNA and protein expression levels of Bcl‑like 11 (Bim)EL, BimL and BimS increased following SchA application. SchA induced the accumulation of acidic vesicles and induced a marked increase in the expression of LC3‑II protein, suggsting that SchA activated the autophagy pathway. However, the expression of the p62 protein was found to be increased by SchA, suggesting that p62 was not degraded during the autophagic flux. The 3‑methyladenine exerted no notable effects on SchA‑induced apoptosis. Taken together, results from the present study suggest that SchA exerted inhibitory effects on NSCLC physiology by inducing cell cycle arrest and apoptosis. In addition, SchA partially induced autophagy, which did not result in any cytoprotective effects.

Gomisin L1, a Lignan Isolated from Schisandra Berries, Induces Apoptosis by Regulating NADPH Oxidase in Human Ovarian Cancer Cells

The fruits of Schisandra chinensis (Schisandra berries) are used as health food supplements and popular food ingredients in East Asia. Lignans, major and characteristic polyphenol compounds of Schisandra berries, possess various biological activities, including hepatoprotective and anticancer effects. However, the biological activities of gomisin L1, a lignan isolated from Schisandra berries, are less to be investigated. In this study, the antitumor activity of gomisin L1 and its underlying molecular mechanism in human ovarian cancer cells were investigated. Gomisin L1 exhibited potent cytotoxic activity against A2780 and SKOV3 ovarian cancer cells. Flow cytometry analysis revealed that the growth inhibitory effects of gomisin L1 were mediated by the induction of apoptosis. Furthermore, gomisin L1 induced an increase in intracellular reactive oxygen species (ROS) levels, and the antioxidant N-acetyl cysteine significantly negated gomisin L1-induced cell death. Moreover, inhibition of NADPH oxidase (NOX) using an inhibitor and siRNA attenuated gomisin L1-induced death of, and ROS production in, human ovarian cancer cells. Taken together, these data indicate that the lignan gomisin L1 from Schisandra berries induces apoptotic cell death by regulating intracellular ROS production via NOX.

Screening of Natural Compounds as P-Glycoprotein Inhibitors against Multidrug Resistance

Multidrug resistance (MDR) is a common problem when fighting cancer with chemotherapy. P-glycoprotein (P-gp, or MDR1) is an active pump responsible for the efflux of xenobiotics out of the cell, including anti-cancer drugs. It is a validated target against MDR. No crystal structure of the human P-gp is available to date, and only recently several cryo-EM structures have been solved. In this paper, we present a comprehensive computational approach that includes constructing the full-length three-dimensional structure of the human P-gp and its refinement using molecular dynamics. We assessed its flexibility and conformational diversity, compiling a dynamical ensemble that was used to dock a set of lignan compounds, previously reported as active P-gp inhibitors, and disclose their binding modes. Based on the statistical analysis of the docking results, we selected a system for performing the structure-based virtual screening of new potential P-gp inhibitors. We tested the method on a library of 87 natural flavonoids described in the literature, and 10 of those were experimentally assayed. The results reproduced the theoretical predictions only partially due to various possible factors. However, at least two of the predicted natural flavonoids were demonstrated to be effective P-gp inhibitors. They were able to increase the accumulation of doxorubicin inside the human promyelocytic leukemia HL60/MDR cells overexpressing P-gp and potentiate the antiproliferative activity of this anti-cancer drug.

Phytochemicals: Potential Lead Molecules for MDR Reversal

Multidrug resistance (MDR) is one of the main impediments in the treatment of cancers. MDR cancer cells are resistant to multiple anticancer drugs. One of the major mechanisms of MDR is the efflux of anticancer drugs by ABC transporters. Increased activity and overexpression of these transporters are important causes of drug efflux and, therefore, resistance to cancer chemotherapy. Overcoming MDR is a fundamental prerequisite for developing an efficient treatment of cancer. To date, various types of ABC transporter inhibitors have been employed but no effective anticancer drug is available at present, which can completely overcome MDR. Phytochemicals can reverse MDR in cancer cells via affecting the expression or activity of ABC transporters, and also through exerting synergistic interactions with anticancer drugs by addressing additional molecular targets. We have listed numerous phytochemicals which can affect the expression and activity of ABC transporters in MDR cancer cell lines. Phytochemicals in the groups of flavonoids, alkaloids, terpenes, carotenoids, stilbenoids, lignans, polyketides, and curcuminoids have been examined for MDR-reversing activity. The use of MDR-reversing phytochemicals with low toxicity to human in combination with effective anticancer agents may result in successful treatment of chemotherapy-resistant cancer. In this review, we summarize and discuss published evidence for natural products with MDR modulation abilities.

Schizandrin A enhances chemosensitivity of colon carcinoma cells to 5-fluorouracil through up-regulation of miR-195

Nowadays 5-fluorouracil (5-FU)-based adjuvant chemotherapy is widely used for treating colon carcinoma. However, 5-FU resistance in the treatment of colon carcinoma has become more common and thereby new therapeutic strategies and new adjuvant drugs still need to be explored. Two 5-FU-resistant colon cancer cell lines, HCT116 and SW480, were used to investigate the effects of Schizandrin A (SchA), 5-FU, or their combination on cell viability and apoptosis. Besides, the role of miR-195 was studied to further clarify the specific function of SchA. CCK-8 assay and flow cytometry analysis were conducted to determine cell viability and apoptosis, respectively. miR-195 expression was determined by quantitative real-time PCR. Cell apoptosis-related proteins and factors of PI3K/AKT and NF-κB pathways were analyzed by Western blot. Cell viability assay showed that SchA treatment at non-toxic dosages caused a marked enhancement of 5-FU-induced cytotoxicity. Moreover, we explored that miR-195 was up-regulated by SchA; and overexpression of miR-195 reduced cell viability and sensitized 5-FU-resistant HCT116 and SW480 cells to 5-FU. The promoting effect of SchA on 5-FU susceptibility can be partly abolished by miR-195 knockdown. Thus it was speculated that SchA might enhance cell chemosensitivity to 5-FU by up-regulating miR-195. Finally, we found that PI3K/AKT and NF-κB pathways were inhibited by high expression of miR-195 reduced by SchA. Our results suggested that SchA sensitized 5-FU-resistant colon carcinoma cells to 5-FU by up-regulating miR-195. SchA combined with 5-FU could be a promising strategy for the adjuvant chemotherapy of colon cancer.

Barbigerone reverses multidrug resistance in breast MCF-7/ADR cells

Development of agents to overcome multidrug resistance (MDR) is one of the important strategies in cancer chemotherapy, and P-glycoprotein (P-gp) correlates with the degree of resistance. As a naturally occurring isoflavone, whether barbigerone (BA) could reverse MDR, is unknown. In this paper, we evaluated effects of BA on reversing P-gp mediated MDR of adriamycin (ADR)-resistant human breast carcinoma (MCF-7/ADR) cells. BA (0.5 μM) treatment showed strong potency to increase ADR cytotoxicity toward MCF-7/ADR cells. It was also demonstrated that BA time- and dose-dependently increased accumulations of ADR and reduced the efflux in MCF-7/ADR cells, pretreatment of these cells with BA might relocalized ADR to the nuclei. Furthermore, the results also revealed that BA did not affect P-gp, but alter P-gp ATPase activity. Intravenous administration of BA significantly increased anticancer efficacy of ADR to MCF-7/ADR xenograft model in nude mice. These results revealed that BA might reverse P-gp mediated MDR through inhibition of ATPase activity, which indicated a novel use of BA as a potent candidate for cancer chemotherapy.

Deoxyschizandrin, Isolated from Schisandra Berries, Induces Cell Cycle Arrest in Ovarian Cancer Cells and Inhibits the Protumoural Activation of Tumour-Associated Macrophages

Deoxyschizandrin, a major lignan of Schisandra berries, has been demonstrated to have various biological activities such as antioxidant, hepatoprotective, and antidiabetic effects. However, the anti-cancer effects of deoxyschizandrin are poorly characterized. In the present study, we investigated the anti-cancer effect of deoxyschizandrin on human ovarian cancer cell lines and tumour-associated macrophages (TAMs). Deoxyschizandrin induced G₀/G₁ phase cell cycle arrest and inhibited cyclin E expression in human ovarian cancer cells. Overexpression of cyclin E significantly reversed the deoxyschizandrin-induced cell growth inhibition. Interestingly, increased production of reactive oxygen species and decreased activation of Akt were observed in A2780 cells treated with deoxyschizandrin, and the antioxidant compromised the deoxyschizandrin-induced cell growth inhibition and Akt inactivation. Moreover, deoxyschizandrin-induced cell growth inhibition was markedly suppressed by Akt overexpression. In addition, deoxyschizandrin was found to inhibit the expression of the M2 phenotype markers CD163 and CD209 in TAMs, macrophages stimulated by the ovarian cancer cells. Moreover, expression and production of the tumour-promoting factors MMP-9, RANTES, and VEGF, which are highly enhanced in TAMs, was significantly suppressed by deoxyschizandrin treatment. Taken together, these data suggest that deoxyschizandrin exerts anti-cancer effects by inducing G₀/G₁ cell cycle arrest in ovarian cancer cells and reducing the protumoural phenotype of TAMs.

Schisandrin B inhibits the proliferation and invasion of glioma cells by regulating the HOTAIR-micoRNA-125a-mTOR pathway

Glioma is one of the most common malignant central nervous system tumors in humans. Schisandrin B (Sch B) has been confirmed to cause the proliferation and invasion of glioma cells. In the present study, the potential mechanism underlying the antitumor effect of Sch B on glioma cells was investigated. The glioma cell lines, U251 and U87, were exposed to Sch B, and the cell viability, apoptosis, migration, and invasion were determined using the MTT assay, flow cytometry, and transwell assay, respectively. Then, the effects of HOTAIR and miR-125a on tumor biology and the mammalian target of rapamycin (mTOR) protein expression in cell lines exposed to Sch B were investigated. The results showed that Sch B decreased HOTAIR expression and increased miR-125a-5p expression. HOTAIR overexpression decreased miR-125a expression and increased mTOR expression in cells with the treatment of Sch B. The miR-125a inhibitor reversed the effects of HOTAIR downregulation on cell proliferation and migration. On co-incubation with rapamycin, a specific mTOR inhibitor, the cell viability, migration, and invasion were decreased and cell apoptosis was increased in two cell lines exposed to Sch B after the treatment of pcDNA-HOTAIR. In conclusion, Sch B played an inhibitory role in the proliferation and invasion of glioma cells by regulating the HOTAIR-micoRNA-125a-mTOR pathway.

Mechanism Underlying the Reversal of Drug Resistance in P-Glycoprotein-Expressing Leukemia Cells by Pinoresinol and the Study of a Derivative

P-glycoprotein (P-gp) is a membrane protein associated with multidrug resistance (MDR) due to its key role in mediating the traffic of chemotherapeutic drugs outside cancer cells, leading to a cellular response that hinders efforts toward successful therapy. With the aim of finding agents that circumvent the MDR phenotype mediated by P-gp, 15 compounds isolated from native and naturalized plants of Argentina were screened. Among these, the non-cytotoxic lignan (±) pinoresinol successfully restored sensitivity to doxorubicin from 7 μM in the P-gp overexpressed human myelogenous leukemia cells, Lucena 1. This resistance-reversing effect was confirmed by competitively increasing the intracellular doxorubicin accumulation and by significantly inhibiting the efflux of doxorubicin and, to a lesser extent, that of rhodamine 123. The activity obtained was similar to that observed with verapamil. No such results were observed in the sensitive parental K562 cell line. To gain deeper insight into the mode of action of pinoresinol, its effect on P-gp function and expression was examined. The docking simulations indicated that the lignan bound to P-gp at the apex of the V-shaped transmembrane cavity, involving transmembrane helices 4, 5, and 6, and partially overlapped the binding region of tariquidar, which was used as a positive control. These results would shed some light on the nature of its interaction with P-gp at molecular level and merit further mechanistic and kinetic studies. In addition, it showed a maximum 29% activation of ATP hydrolysis and antagonized verapamil-stimulated ATPase activity with an IC₅₀ of 20.9 μM. On the other hand, pinoresinol decreased the presence of P-gp in the cell surface. Derivatives of pinoresinol with improved activity were identified by docking studies. The most promising one, the non-cytotoxic 1-acetoxypinoresinol, caused a reversion of doxorubicin resistance from 0.11 μM and thus higher activity than the lead compound. It also caused a significant increase in doxorubicin accumulation. Results were similar to those observed with verapamil. The results obtained positioned these compounds as potential candidates for effective agents to overcome P-gp-mediated MDR, leading to better outcomes for leukemia chemotherapy.

Effect of traditional Chinese medicine components on multidrug resistance in tumors mediated by P-glycoprotein

Multidrug resistance (MDR) is a major cause of chemotherapy failure. It occurs when an organism is resistant to one type of drug, but also develops resistance to other drugs with different structures and targets. There is a high incidence of MDR in cancer chemotherapy, therefore, finding an effective and non-toxic MDR reversal agent is an important goal, particularly for P-glycoprotein-mediated MDR in cancer. Improvements continue to be made to the status and understanding of traditional Chinese medicine (TCM), due to the advantages of low toxicity and relatively minor side effects. Therefore TCM is currently being used in the treatment of various types of diseases. In recent years, numerous components of TCM have been identified to be effective in reversing MDR by downregulating expression of the drug transporter membrane protein, recovering changes in enzymes involved in detoxification and metabolism and repairing the cell apoptosis pathway. The present study summarizes the anticancerous properties and MDR reversing components of traditional medicinal plants commonly used in the treatment of cancer.

A microemulsion co-loaded with Schizandrin A-docetaxel enhances esophageal carcinoma treatment through overcoming multidrug resistance

Multidrug resistance (MDR) is the major underlying cause of the low 5-year survival rate of esophageal carcinoma. In this study, we developed a novel microemulsion system (SD-ME) co-loaded with docetaxel (DTX) and Schizandrin A, a potent chemotherapeutic agent and a potential drug resistance modulator, respectively. In the physicochemical characterization studies, SD-ME displayed a well-defined spherical shape and size (56.62 ± 4.16 nm), a narrow polydispersity index (PDI, 0.132 ± 0.002), and a negative surface charge (−19.81 ± 3.11 mv). In the cellular uptake studies, SD-ME with a DTX concentration of 30 μg/mL exhibited a 3.9-fold enhancement of DTX internalization in DTX-resistant EC109 (EC109/DDR) cells in comparison to that observed for EC109 cells, and the mechanisms were associated with reducing P-gp expression and inhibiting P-gp ATPease. The half-maximal inhibitory concentrations (IC₅₀) of DTX and SD-ME against EC109/DDR cells were 40.57 ± 0.39 and 3.59 ± 0.06 μg/mL, respectively. Likewise, the apoptotic rate of EC109/DDR treated with SD-ME increased up to 20-fold compared to that observed with free DTX. In anticancer efficacy studies in vivo, SD-ME markedly retarded the tumor growth of nude mice bearing EC109/DDR tumor xenografts compared with D-ME and free DTX throughout the duration of study. Consequently, mice treated with SD-ME had the highest survival rate (37.5%) during the observation period (70 days). In addition, there were no apparent side effects after the administration of SD-ME. Overall, our study provides evidence for SD-ME as an effective drug delivery system for enhanced MDR tumor treatment.

Quinone derivatives isolated from the endolichenic fungus Phialocephala fortinii are Mdr1 modulators that combat azole resistance in Candida albicans

One of the main azole-resistance mechanisms in Candida pathogens is the upregulation of drug efflux pumps, which compromises the efficacy of azoles and results in treatment failure. The combination of azole-antifungal agents with efflux pump inhibitors represents a promising strategy to combat fungal infection. High-throughput screening of 150 extracts obtained from endolichenic fungal cultures led to the discovery that the extract of Phialocephala fortinii exhibits potent activity for the reversal of azole resistance. From P. fortinii cultures, a total of 15 quinone derivatives, comprising 11 new derivatives and 4 known compounds, were obtained. Among these compounds, palmarumycin P3 (3) and phialocephalarin B (8) specifically modulate the expression of MDR1 to inhibit the activity of drug efflux pumps and therefore reverse azole resistance. The present study revealed Mdr1 targeting as an alternative mechanism for the discovery of new agents to fight antifungal drug resistance.

Clinical Experiences of Korean Medicine Treatment against Urinary Bladder Cancer in General Practice

Urinary bladder cancer (UBC) is one of the most common cancers, with 1 out of every 26 men and 1 out of every 80 women worldwide developing the disease during their lifetime. Moreover, it is a disease that predominantly affects the elderly and is becoming a major health problem as the elderly population continues to rapidly increase. In spite of the rapid development of medical science, the 5-year survival rate has remained around 75% since the 1990s, and the FDA has approved no new drugs for UBC over the last 10 years. In addition, most patients experience frequent recurrence and poor quality of life after diagnosis. Therefore, in order to solve unmet needs by alternative methods, we present our clinical cases of UBC where we observed outstanding results including regression and recurrence prevention exclusively through Traditional Korean Medicine such as (1) herbal therapy, (2) acupuncture, (3) pharmacopuncture and needle-embedding therapy, (4) moxibustion, and (5) cupping therapy. From our experience, it appears that multimodal strategies for synergistic efficiency are more effective than single Korean Medicine treatment. We hope this will encourage investigation of the efficacy of Korean Medicine treatment in clinical trials for UBC patients.

Development of in Silico Models for Predicting P-Glycoprotein Inhibitors Based on a Two-Step Approach for Feature Selection and Its Application to Chinese Herbal Medicine Screening

P-glycoprotein (P-gp) is regarded as an important factor in determining the ADMET (absorption, distribution, metabolism, elimination, and toxicity) characteristics of drugs and drug candidates. Successful prediction of P-gp inhibitors can thus lead to an improved understanding of the underlying mechanisms of both changes in the pharmacokinetics of drugs and drug-drug interactions. Therefore, there has been considerable interest in the development of in silico modeling of P-gp inhibitors in recent years. Considering that a large number of molecular descriptors are used to characterize diverse structural moleculars, efficient feature selection methods are required to extract the most informative predictors. In this work, we constructed an extensive available data set of 2428 molecules that includes 1518 P-gp inhibitors and 910 P-gp noninhibitors from multiple resources. Importantly, a two-step feature selection approach based on a genetic algorithm and a greedy forward-searching algorithm was employed to select the minimum set of the most informative descriptors that contribute to the prediction of P-gp inhibitors. To determine the best machine learning algorithm, 18 classifiers coupled with the feature selection method were compared. The top three best-performing models (flexible discriminant analysis, support vector machine, and random forest) and their ensemble model using respectively only 3, 9, 7, and 14 descriptors achieve an overall accuracy of 83.2%-86.7% for the training set containing 1040 compounds, an overall accuracy of 82.3%-85.5% for the test set containing 1039 compounds, and a prediction accuracy of 77.4%-79.9% for the external validation set containing 349 compounds. The models were further extensively validated by DrugBank database (1890 compounds). The proposed models are competitive with and in some cases better than other published models in terms of prediction accuracy and minimum number of descriptors. Applicability domain then was addressed by developing an ensemble classification model to obtain more reliable predictions. Finally, we employed these models as a virtual screening tool for identifying potential P-gp inhibitors in Traditional Chinese Medicine Systems Pharmacology (TCMSP) database containing a total of 13 051 unique compounds from 498 herbs, resulting in 875 potential P-gp inhibitors and 15 inhibitor-rich herbs. These predictions were partly supported by a literature search and are valuable not only to develop novel P-gp inhibitors from TCM in the early stages of drug development, but also to optimize the use of herbal remedies.

Effects of Schisandra chinensis extract on gastrointestinal motility in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (Turcz.) Baill. (SC) continues to be used as a traditional folk medicine in Asia, especially for the treatment of gastrointestinal (GI) disorders related to gastritis, diarrhea, enterocolitis and abnormal GI motility.

AIM OF THE STUDY

Because GI disorders, especially abnormal GI motility, are major lifelong problems, we investigated the effects of SC on the pacemaker activity of the interstitial cells of Cajal (ICCs) in murine small intestine and GI motility.

MATERIALS AND METHODS

Enzymatic digestions were used to dissociate ICCs from small intestines, and the whole-cell patch-clamp configuration was used to record potentials generated by cultured ICCs. In vivo effects of SC on GI motility were investigated by measuring the intestinal transit rate (ITR) of Evans blue in normal and GI motility dysfunction mice.

RESULTS

SC extracts depolarized the membrane potentials of ICCs in a dose dependent manner. Pretreatment with Ca(2+) free solution or thapsigargin (a Ca(2+)-ATPase inhibitor in the endoplasmic reticulum) abolished the generation of pacemaker potentials by ICCs, and under these conditions, SC extract did not depolarize the membrane potentials of ICCs. In addition, membrane depolarizations were inhibited by intracellular GDPβS and by U-73122 (an active phospholipase C (PLC) inhibitor). In normal mice, ITRs were significantly increased by SC extract (0.1-1g/kg, intragastrically (i.g.)) in a dose dependent manner. Also, SC extract significantly recovered the GI motility dysfunctions in acetic acid (AA)-injected and streptozotocin (STZ)-induced diabetic mice, which are the GI motility animal models.

MATERIALS AND METHODS

SC extract modulates pacemaker potentials in ICCs in a dose dependent manner via external and internal Ca(2+) regulations, and via G protein and the PLC pathway. In addition, SC extract increased ITRs in normal and abnormal GI motility mice models. This study shows that SC extract offers a basis for the development of a prokinetic agent that prevents or alleviates GI motility dysfunctions.

Protective effect of Wuzhi tablet (Schisandra sphenanthera extract) against cisplatin-induced nephrotoxicity via Nrf2-mediated defense response

Cisplatin is a potent anti-cancer agent for various types of tumors. However, the clinical use of cisplatin is often limited by its nephrotoxicity. This study reports that WZ tablet (WZ, a preparation of an ethanol extract of Schisandra sphenanthera) mitigates cisplatin-induced toxicity in renal epithelial HK-2 cells and in mice. Pretreatment of HK-2 cells with WZ ameliorated cisplatin-induced cytotoxicity caused by oxidative stress, as was demonstrated by reductions in the levels of reactive oxygen species (ROS) and increased levels of glutathione (GSH). WZ facilitated the nuclear accumulation of the transcription factor NF-E2-related factor 2 (Nrf2) and the subsequent expression of its target genes such as

NAD(P)H

quinine oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1) and glutamate cysteine ligase (GCL). Protective effects of WZ on cisplatin-induced nephrotoxicity were also observed in mice. WZ attenuated cisplatin-induced renal dysfunction, structural damage and oxidative stress. The nuclear accumulation of Nrf2 and its target genes were increased by WZ treatment. Taken together, these findings demonstrated WZ have a protective effect against cisplatin-induced nephrotoxicity by activation of the Nrf2 mediated defense response, which is of significant importance for therapeutic intervention in cisplatin induced renal injury.

Herb-drug pharmacokinetic interaction of a traditional chinese medicine jia-wei-xiao-yao-san with 5-Fluorouracil in the blood and brain of rat using microdialysis

According to a survey from the National Health Insurance Research Database (NHIRD), Jia-Wei-Xiao-Yao-San (JWXYS) is the most popular Chinese medicine for cancer patients in Taiwan. 5-Fluorouracil (5-FU) is a general anticancer drug for the chemotherapy. To investigate the herb-drug interaction of JWXYS on pharmacokinetics of 5-FU, a microdialysis technique coupled with a high-performance liquid chromatography system was used to monitor 5-FU in rat blood and brain. Rats were divided into four parallel groups, one of which was treated with 5-FU (100 mg/kg, i.v.) alone and the remaining three groups were pretreated with a different dose of JWXYS (600, 1200, or 2400 mg/kg/day for 5 consecutive days) followed by a combination with 5-FU. This study demonstrates that 5-FU with JWXYS (600 mg/kg/day or 1200 mg/kg/day) has no significant effect on the pharmacokinetics of 5-FU in the blood and brain. However, JWXYS (2400 mg/kg/day) coadministered with 5-FU extends the elimination half-life and increases the volume of distribution of 5-FU in the blood. The elimination half-life of 5-FU in the brain for the pretreatment group with 2400 mg/kg/day of JWXYS is significantly longer than that for the group treated with 5-FU alone and also reduces the clearance. This study provides practical dosage information for clinical practice and proves the safety of 5-FU coadministered with JWXYS.

Schisandrin A enhances the cytotoxicity of doxorubicin by the inhibition of nuclear factor-kappa B signaling in a doxorubicin-resistant human osteosarcoma cell line

Schisandrin A reversed chemoresistance in doxorubicin-induced MG-63 subline by inhibiting NF-kappaB-mediate expression of P-gp.

Multiple drug resistance due to resistance to stem cells and stem cell treatment progress in cancer (Review)

In recent years, the cancer stem cell (CSC) theory has provided a new angle in the research of cancer, and has gradually gained significance. According to this theory, the multiple drug resistance (MDR) of cancer is most likely due to the resistance of CSCs, and a significant quantity of research has been carried out into the MDR mechanisms of CSC. Over time, some of these mechanisms have been gradually accepted, including ATP-binding cassette transporters, aldehyde dehydrogenase, the CSC microenvironment and epithelial to mesenchymal transition. In the present review, we summarize these mechanisms in detail and review possible appropriate therapy plans against CSCs based on CSC theory.

In vitro, in vivo and ex vivo characterization of ibrutinib: a potent inhibitor of the efflux function of the transporter MRP1

BACKGROUND AND PURPOSE

The transporter, multidrug resistance protein 1 (MRP1, ABCC1), plays a critical role in the development of multidrug resistance (MDR). Ibrutinib is an inhibitor of Bruton's tyrosine kinase. Here we investigated the reversal effect of ibrutinib on MRP1-mediated MDR.

EXPERIMENTAL APPROACH

Cytotoxicity was determined by MTT assay. The expression of protein was detected by Western blot. RT-PCR and Q-PCR were performed to detect the expression of MRP1 mRNA. The intracellular accumulation and efflux of substrates for MRP1 were measured by scintillation counter and flow cytometry. HEK293/MRP1 cell xenografts in nude mice were established to study the effects of ibrutinib in vivo.

KEY RESULTS

Ibrutinib significantly enhanced the cytotoxicity of MRP1 substrates in HEK293/MRP1 and HL60/Adr cells overexpressing MRP1. Furthermore, ibrutinib increased the accumulation of substrates in these MRP1-overexpressing cells by inhibiting the drug efflux function of MRP1. However, mRNA and protein expression of MRP1 remained unaltered after treatment with ibrutinib in MRP1-overexpressing cells. In vivo, ibrutinib enhanced the efficacy of vincristine to inhibit the growth of HEK293/MRP1 tumour xenografts in nude mice. Importantly, ibrutinib also enhances the cytotoxicity of vincristine in primary cultures of leukaemia blasts, derived from patients.

CONCLUSIONS AND IMPLICATIONS

Our results indicated that ibrutinib significantly increased the efficacy of the chemotherapeutic agents which were MRP1 substrates, in MRP1-overexpressing cells, in vitro, in vivo and ex vivo. These findings will lead to further studies on the effects of a combination of ibrutinib with chemotherapeutic agents in cancer patients overexpressing MRP1.

Antidiabetic Effect of Schisandrae Chinensis Fructus Involves Inhibition of the Sodium Glucose Cotransporter

Preclinical Research Schisandrae Chinensis Fructus (SCF), the fruit of Schisandra chinensis (Turcz.) Baill. (family Schisandraceae) is traditionally used as a tonic and antidiabetic agent in Asia. In this study, SCF was investigated for its effects on sodium glucose cotransporters 1 and 2 (SGLT 1 and 2) expressed in a COS-7 cell line for its specificity in inhibiting SGLT2, which is a novel mechanism to screen for potential antidiabetic agents. Using a bioassay-guided fractionation, we then tried to isolate and identify the active fraction(s)/component(s). The ethanol extract of SCF at a concentration of 1 mg/mL significantly inhibited 89% of SGLT1 and 73% of SGLT2 activities in a [¹⁴ C]-α-methyl-d-glucopyranoside ([¹⁴ C]-AMG) uptake assay. Fractionation of the ethanol extract yielded nine fractions, of which F8, at a concentration of 1 mg/mL, was specific in inhibiting SGLT 2 (42% inhibition, P < 0.001), without inhibiting SGLT 1. Using LC/MS-MS, three compounds, deoxyschisandrin, schisandrin B (γ-schisandrin) and schisandrin were identified in F8 and their amounts quantified. However, subsequent evaluation in the [¹⁴ C]-AMG uptake assay showed that these three compounds failed to inhibit SGLT 2 activity indicating that the SGLT active component(s) from SCF have yet to be identified. Drug Dev Res 76 : 1-8, 2015.

Identification of key structural characteristics of Schisandra chinensis lignans involved in P-glycoprotein inhibition

The aim of the present study was to determine the structural requirements for dibenzocyclooctadiene lignans essential for P-glycoprotein inhibition. Altogether 15 structurally related lignans isolated from Schisandra chinensis or prepared by modification of their backbone were investigated, including three pairs of enantiomers. P-Glycoprotein inhibition was quantified using a doxorubicin accumulation assay in human promyelotic leukemia HL60/MDR cells overexpressing P-glycoprotein. A preliminary quantitative structure-activity relationship analysis revealed three main structural features involved in P-glycoprotein inhibition: a 1,2,3-trimethoxy moiety, a 6-acyloxy group, and the absence of a 7-hydroxy group. The most effective inhibitors, (-)-gomisin N (1) and (+)-deoxyschizandrin [(+)-2], were selected for further evaluation of their effects. Both these lignans restored the cytotoxic effect of doxorubicin in HL60/MDR cells and when combined with a subtoxic concentration of this compound increased the proportion of G2/M cells significantly, which is a usual response to treatment with this anticancer drug.

Gene expression profiling of sesaminol triglucoside and its tetrahydrofuranoid metabolites in primary rat hepatocytes

Sesaminol triglucoside is a major lignin in sesame meal and has a methylenedioxyphenyl group and multiple functions in vivo. As a tetrahydrofurofuran type lignan, sesaminol triglucoside is metabolized to mammalian lignans. This investigation studies the effect of sesaminol triglucoside and its tetrahydrofuranoid metabolites (sesaminol, 2-episesaminol, hydroxymethyl sesaminol-tetrahydrofuran, enterolactone, and enterodiol) on gene expression in primary rat hepatocytes using a DNA microarray. Sesame lignans significantly affected the expression of xenobiotic-induced transcripts of cytochrome P450, solute carrier (SLC), and ATP-binding cassette (ABC) transporters. Changes in gene expression were generally greater in response to metabolites with methylenedioxyphenyl moieties (sesaminol triglucoside, sesaminol, and 2-episesaminol) than to the tetrahydrofuranoid metabolites (hydroxymethyl sesaminol-tetrahydrofuran, enterolactone, and enterodiol). Tetrahydrofuran lignans, such as sesaminol triglucoside, sesamin, hydroxymethyl sesaminol-tetrahydrofuran, and sesaminol changed the expression of ABC transporters.

Gomisin A inhibits lipopolysaccharide-induced inflammatory responses in N9 microglia via blocking the NF-κB/MAPKs pathway

Gomisin A, one of the major dibenzocyclooctadiene lignans isolated from Schisandra chinensis Baill., has proved to possess a variety of pharmacological effects. The aim of the present study was to investigate the anti-inflammatory and neuroprotective effects of gomisin A as well as its potential molecular mechanisms. It was found that gomisin A not only inhibited the production of NO and PGE2 in a concentration-dependent manner but also suppressed the expressions of iNOS and COX-2 in LPS-stimulated N9 microglia without observable cytotoxicity. Gomisin A was also able to attenuate the mRNA expression and the production of pro-inflammatory factors TNF-α, IL-1β and IL-6. Moreover, LPS induced reactive oxygen species (ROS) production, NADPH oxidase activation, and gp91phox expression, which were markedly inhibited by gomisin A in microglia. Furthermore, the data showed that gomisin A significantly down-regulated the TLR4 protein expression, and inhibited nuclear transcription factor (NF)-κB and mitogen-activated protein kinases (MAPKs) signaling pathways. Additionally, gomisin A alleviated the cell death of SH-SY5Y neuroblastoma, rat primary cortical and hippocampal neurons induced by the conditioned-media from activated microglia. In summary, gomisin A may exert neuroprotective effects by attenuating the microglia-mediated neuroinflammatory response via inhibiting the TLR4-mediated NF-κB and MAPKs signaling pathways.

Reversal effect of bufalin on multidrug resistance in human hepatocellular carcinoma BEL-7402/5-FU cells

Multidrug resistance (MDR) is a major obstacle to chemotherapy in patients with hepatocellular carcinoma (HCC). To overcome MDR and improve chemotherapeutic efficacy, novel reversal agents with higher efficacy and lower toxicity are urgently needed for HCC. The present study was designed to examine the potential reversal activity of bufalin, a toxic ligand isolated from the traditional Chinese medicine 'Chansu' and to elucidate the possible related mechanisms. A multidrug-resistant HCC cell line, BEL-7402/5-FU, was used as the cell model. The working concentration of bufalin as an effective reversal agent, and the cell viability in the reversal experiments were determined by MTT assay. The effects of bufalin at a non-cytotoxic dose on cell cycle distribution, apoptosis and drug efflux pump activity were measured by flow cytometry. Qualitative observation of apoptosis was also carried out by confocal microscopy. Furthermore, the effects of bufalin on the expression of potential genes involved in MDR of BEL-7402/5-FU cells, including thymidylate synthase (TS), P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), B-cell lymphoma-extra large (Bcl-xL) and Bcl-2-associated X protein (Bax), were determined using real-time PCR and western blot analysis. The results showed that bufalin at a concentration of 1 nM enhanced the chemosensitivity of BEL-7402/5-FU cells to 5-FU with a reversal fold of 3.8 which was similar to that of 1 µM verapamil. Bufalin significantly arrested the cell cycle at the G₀/G₁ phase, induced apoptosis through an increase in the Bax/Bcl-xL ratio, inhibited drug efflux pump activity via downregulation of MRP1, and reduced the expression of TS in BEL-7402/5-FU cells. The present study revealed that bufalin effectively reversed MDR in BEL-7402/5-FU cells through multiple pathways. The combination of bufalin with cytotoxic drugs may serve as a promising strategy for the chemotherapy of HCC.

Reversal effects of Rabdosia rubescens extract on multidrug resistance of MCF-7/Adr cells in vitro

CONTEXT

Rabdosia rubescens (Hemsl.) Hara (Lamiaceae) is widely used in traditional Chinese medicines for the treatment of antitumor, antimicrobial, anti-inflammatory and antioxidation. It is also used as a supplement in the treatment of many cancers, such as esophagus, mammary gland, liver and prostate cancers.

OBJECTIVE

To investigate the multidrug resistance (MDR) reversal effects and its possible mechanism of R. rubescens extracts on human breast cancer cell line MCF-7/Adr (Michigan Cancer Foundation--7/adriamycin resistance).

MATERIALS AND METHODS

Rabdosia rubescens were extracted by reflux extraction method with different solvent such as petroleum ether, chloroform, ethyl acetate, n-butyl alcohol and water in order and obtain petroleum ether fraction (PEF), chloroform fraction (CF), ethyl acetate fraction (EAF), n-butyl alcohol fraction (BAF) and aqueous fraction (AF). The active extract fractions of R. rubescens were screened by rhodamine123 (Rh123) accumulation assay. Cytotoxicity of the effect fraction was examined by the MTT assay; the intracellular accumulation of adriamycin and expression of P-gp were examined by flow cytometry; the gene transcription of MDR1 was determined by RT-PCR.

RESULTS

CF and EAF fractions could increase the intracellular accumulation of adriamycin in MCF-7/Adr cells, PEF, BAF and AF fractions showed little effect on the intracellular accumulation of adriamycin or Rh123. When adriamycin was used in combination with CF and EAF fractions at non-toxic concentration on MCF-7/Adr cells, CF and EAF fractions can reverse MDR of MCF-7/Adr cells, and the reverse folds were 2.16 (CF, 4 μg/mL), 4.60 (CF, 20 μg/mL), 1.87 (EAF, 4 μg/mL) and 4.02 (EAF, 20 μg/mL), respectively. After treatment with CF (4.20 μg/mL) and EAF (4.20 μg/mL) for 48 h, the MDR1 gene expression level in MCF-7/Adr cells was decreased by 40.17, 48.14, 33.86 and 42.52%, and the abundance of P-gp also decreased by 8.63, 24.53, 27.50 and 34.91% in MCF-7/Adr cells, respectively.

DISCUSSION AND CONCLUSION

These results indicate the therapeutic value of chloroform fraction (CF) and ethyl acetate fraction (EAF) from R. rubescens as potential MDR reversing agents and warranted further investigation.

Effect of acupuncture on target tissue distribution of Schisandra lignans

BACKGROUND

Recently, the combination of acupuncture and Chinese medicine as a practical strategy to treat diseases is receiving considerable attention worldwide as they are usually found to exhibit intriguing therapeutic effectiveness. The current study aimed to study the adjunct effect of acupuncture on target tissue distribution of schisandra lignans when acupuncture is combined with Schisandra chinensis.

METHODS

A simple and reliable high performance liquid chromatography-electrospray tandem-mass spectrometry (HPLC-ESI-MS) method for simultaneous analysis of three bioactive lignans (schisandrin, deoxyschisandrin and schisandrin B) in rat tissues was established. Using this analytical method we evaluated whether acupuncture had a synergistic effect on the tissue distribution of schisandra lignans.

RESULTS

Tissue concentrations of the three lignans in the group receiving acupuncture were significantly higher than those in the schisandra only group, suggesting that acupuncture may potently increase tissue concentrations of schisandra lignans. The highest concentrations of the three lignans occurred in the liver compared with other tissues, and tissue concentrations in the heart, spleen, lungs and kidneys were increased by 315%, 203%, 250% and 224%, respectively. In addition, retention times of the lignans in tissues were prolonged for a relative long time.

CONCLUSIONS

Our date indicate that the combined use of acupuncture and Schisandra chinensis could produce a synergistic effect which could play a beneficial role on promoting the tissue distribution of lignans. This has supported our initial hypothesis. The HPLC-MS method showed good sensitivity in quantifying the three schisandra lignans in different tissues.

Reversal effect of rosmarinic acid on multidrug resistance in SGC7901/Adr cell

Multidrug resistance (MDR) has been a major problem in cancer chemotherapy. In this study, the aim was to explore the reversal effect and its potential mechanism of rosmarinic acid (RA) on SGC7901/Adr cells. 3-(4,5-Dimethylthiazol)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to investigate the reversal index of RA in SGC7901/Adr cell line. The intracellular accumulation of adriamycin, rhodamine123 (Rh123), and the expression of P-glycoprotein (P-gp) were assayed by flow cytometry. The influence of RA on the transcription of MDR1 gene was determined by reverse transcription-polymerase chain reaction. The results showed that RA could reverse the MDR of SGC7901/Adr cells, increase the intracellular accumulation of Adr and Rh123, and decrease the transcription of MDR1 gene and the expression of P-gp in SGC7901/Adr cells. These results indicated that RA was a potential multidrug resistance-reversing agent and warranted further investigations.

BBA, a derivative of 23-hydroxybetulinic acid, potently reverses ABCB1-mediated drug resistance in vitro and in vivo

23-O-(1,4'-Bipiperidine-1-carbonyl)betulinic acid (BBA), a synthetic derivative of 23-hydroxybetulinic acid (23-HBA), shows a reversal effect on multidrug resistance (MDR) in our preliminary screening. Overexpression of ATP-binding cassette (ABC) transporters such as ABCB1, ABCG2, and ABCC1 has been reported in recent studies to be a major factor contributing to MDR. Our study results showed that BBA enhanced the cytotoxicity of ABCB1 substrates and increased the accumulation of doxorubicin or rhodamine123 in ABCB1 overexpressing cells, but had no effect on non ABCB1 substrate, such as cisplatin; what's more, BBA slightly reversed ABCG2-mediated resistance to SN-38, but did not affect the ABCC1-mediated MDR. Further studies on the mechanism indicated that BBA did not alter the expression of ABCB1 at mRNA or protein levels, but affected the ABCB1 ATPase activity by stimulating the basal activity at lower concentrations and inhibiting the activity at higher concentrations. In addition, BBA inhibited the verapamil-stimulated ABCB1 ATPase activity and the photolabeling of ABCB1 with [(125)I] iodoarylazidoprazosin in a concentration-dependent manner, indicating that BBA directly interacts with ABCB1. The docking study confirmed this notion that BBA could bind to the drug binding site(s) on ABCB1, but its binding position was only partially overlapping with that of verapamil or iodoarylazidoprazosin. Importantly, BBA increased the inhibitory effect of paclitaxel in ABCB1 overexpressing KB-C2 cell xenografts in nude mice. Taken together, our findings suggest that BBA can reverse ABCB1-mediated MDR by inhibiting its efflux function of ABCB1, which supports the development of BBA as a novel potential MDR reversal agent used in the clinic.

Reversion of multidrug resistance in a chemoresistant human breast cancer cell line by β-elemene

BACKGROUND

Multidrug resistance (MDR) presents a problem in cancer chemotherapy, and developing new agents to overcome MDR is important. This study intends to investigate the reversal effect of -elemene on MDR in human breast carcinoma MCF-7 and doxorubicin-resistant MCF-7 cells.

METHODS

MTT cytotoxicity assays, flow cytometry, and Western blot analysis were performed to investigate the antiproliferative effects of the combination of anticancer drugs with -elemene, to study the reversal of drug resistance, and to examine the inhibitory effects on protein expression.

RESULTS

The results showed that -elemene (30 μ mol/l) had a strong potency to increase the cytotoxicity of doxorubicin to MCF-7/DOX cells, with a reversal fold of 6.38. In addition, the mechanisms of -elemene in reversing P-glycoprotein (Pgp)-mediated MDR demonstrated that -elemene significantly increases the intracellular accumulations of doxorubicin and Rh123 via inhibition of the P-gp transport function in MCF-7/DOX cells. Flow cytometry and Western blot analyses revealed that -elemene could inhibit the expression of P-gp, while it had little effect on the expression of MRP1 protein. In addition, -elemene had little inhibitory effect on the intracellular GSH levels and GST activities in MCF-7/DOX cells.

CONCLUSIONS

-Elemene might represent a promising agent for overcoming MDR in cancer therapy.

Effects of schizandrin on the expression of thymic stromal lymphopoietin in human mast cell line HMC-1

AIMS

Thymic stromal lymphopoietin (TSLP) plays an important role in allergic diseases such as asthma and atopic dermatitis. Schizandrin has various effects such as anti-asthmatic, anti-cancer and anti-inflammatory effects. However, the effect of schizandrin on the production of TSLP has not been clarified. Thus, we investigated how schizandrin inhibits the production of TSLP in the human mast cell line HMC-1 cells.

MAIN METHODS

We used enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, luciferase assay, and Western blot analysis to investigate the effects of schizandrin.

KEY FINDINGS

Schizandrin inhibited the production and mRNA expression of TSLP in HMC-1 cells. The maximal inhibition rate of TSLP production by schizandrin (10 μM) was 68.62 ± 3.47%. Schizandrin inhibited the translocation and luciferase activity of nuclear factor-κB induced by phorbol myristate acetate plus A23187. In the activated HMC-1 cells, the activation of caspase-1 was increased, whereas the activation of caspase-1 was decreased by pretreatment with schizandrin.

SIGNIFICANCE

These results suggest that schizandrin can be used to treat inflammatory and atopic diseases through the inhibition of TSLP.

Schisandrin B attenuates cancer invasion and metastasis via inhibiting epithelial-mesenchymal transition

Background

Metastasis is the major cause of cancer related death and targeting the process of metastasis has been proposed as a strategy to combat cancer. Therefore, to develop candidate drugs that target the process of metastasis is very important. In the preliminary studies, we found that schisandrin B (Sch B), a naturally-occurring dibenzocyclooctadiene lignan with very low toxicity, could suppress cancer metastasis.

Methodology

BALB/c mice were inoculated subcutaneously or injected via tail vein with murine breast cancer 4T1 cells. Mice were divided into Sch B-treated and control groups. The primary tumor growth, local invasion, lung and bone metastasis, and survival time were monitored. Tumor biopsies were examined immuno- and histo-pathologically. The inhibitory activity of Sch B on TGF-β induced epithelial-mesenchymal transition (EMT) of 4T1 and primary human breast cancer cells was assayed.

Principal Findings

Sch B significantly suppressed the spontaneous lung and bone metastasis of 4T1 cells inoculated s.c. without significant effect on primary tumor growth and significantly extended the survival time of these mice. Sch B did not inhibit lung metastasis of 4T1 cells that were injected via tail vein. Delayed start of treatment with Sch B in mice with pre-existing tumors did not reduce lung metastasis. These results suggested that Sch B acted at the step of local invasion. Histopathological evidences demonstrated that the primary tumors in Sch B group were significantly less locally invasive than control tumors. In vitro assays demonstrated that Sch B could inhibit TGF-β induced EMT of 4T1 cells and of primary human breast cancer cells.

Conclusions

Sch B significantly suppresses the lung and bone metastasis of 4T1 cells via inhibiting EMT, suggesting its potential application in targeting the process of cancer metastasis.

P-glycoprotein and its inhibition in tumors by phytochemicals derived from Chinese herbs

P-glycoprotein belongs to the family of ATP-binding cassette (ABC) transporters. It functions in cellular detoxification, pumping a wide range of xenobiotic compounds, including anticancer drugs out of the cell. In cancerous cells, P-glycoprotein confers resistance to a broad spectrum of anticancer agents, a phenomenon termed multidrug resistance. An attractive strategy for overcoming multidrug resistance is to block the transport function of P-glycoprotein and thus increase intracellular concentrations of anticancer drugs to lethal levels. Efforts to identify P-glycoprotein inhibitors have led to numerous candidates, none of which have passed clinical trials with cancer patients due to their high toxicity. The search for naturally inhibitory products from traditional Chinese medicine may be more promising because natural products are frequently less toxic than chemically synthesized substances. In this review, we give an overview of molecular and clinical aspects of P-glycoprotein and multidrug resistance in the context of cancer as well as Chinese herbs and phytochemicals showing inhibitory activity towards P-glycoprotein.

Schisandra chinensis reverses visceral hypersensitivity in a neonatal-maternal separated rat model

Visceral hypersensitivity is an important characteristic feature of functional gastrointestinal disorders, such as irritable bowel syndrome (IBS). This study evaluated the effect of Schisandra chinensis on visceral hyperalgesia induced by neonatal maternal separation (NMS) in an IBS rat model. The visceromotor responses to colorectal balloon distension (CRD) were measured by abdominal withdrawal reflex (AWR) and electromyographic (EMG) activities. NMS control rats (receiving vehicle) underwent aggravated visceral pain in response to CRD as compared to normal rats, evidenced by the reduced pain threshold, enhanced AWR scores and EMG responses. Treatment with a 70% ethanol extract of S. chinensis (0.3g/kg and 1.5g/kg/day) for 7 days resulted in an increase in the pain threshold (NMS control: 19.1±1.0mmHg vs low-dose: 24.8±1.3mmHg and high-dose: 25.2±1.8mmHg, p<0.01), and abolished the elevated AWR and EMG responses to CRD in NMS rats (AUC values of EMG response curve were: 1952±202 in NMS control group vs 1074±90 in low-dose group and 1145±92 in high-dose group, p<0.001), indicating that S. chinensis could reverse the visceral hypersensitivity induced by early-life stress event. The result of ELSA measurement shows that the elevated serotonin (5-HT) level in the distal colon of NMS rats returned to normal level after treatment with S. chinensis. Moreover, the increase in pain threshold in rats treated with S. chinensis was associated with a decline of the mRNA level of 5-HT(3) receptor in the distal colon. All available results demonstrate that S. chinensis can reverse visceral hypersensitivity induced by neonatal-maternal separation, and the effect may be mediated through colonic 5-HT pathway in the rat.