Multidrug Resistance Reversal Agents Research Articles

Cantharidin reverses multidrug resistance of human hepatoma HepG2/ADM cells via down-regulation of P-glycoprotein expression

Multidrug resistance (MDR) is a serious obstacle encountered in cancer treatment. In this study, we established an in vitro multiple drug resistant HepG2 cell line (HepG2/ADM), and characterized its MDR. This model was used to screen potential candidate chemosensitisers from over 200 purified naturally occurring compounds extracted from plants and animals. Cantharidin was found to have a significant reversal on MDR in our model. Further, our results showed that Cantharidin could significantly inhibit P-gp (P-glycoprotein) expression, mRNA transcription, as well as MDR1 promoter activity. These results suggest that Cantharidin is a novel and potent MDR reversal agent and may be a potential adjunctive agent for tumor chemotherapy.

The Enantioselective Total Synthesis and Unambiguous Proof of the Absolute Stereochemistry of Pervilleine C

The first enantioselective, total synthesis of the naturally occurring, potent cancer MDR reversal agent pervilleine C is reported. Each enantiomer of the natural product has been prepared as well as the enantiomers of the corresponding 8-oxa-pervilleine C.

Reversal of Multidrug Resistance by Synthetic and Natural Compounds in Drug-Resistant MCF-7 Cell Lines

Background: Ineffectiveness of anticancer drugs is frequently observed in cancer chemotherapy. The resistance of tumor cells to various cytotoxic drugs is defined as multidrug resistance (MDR). The purpose of this study is to investigate the potential reversal effect of some synthetic and natural chemicals on drug-resistant MCF-7 cell lines. The effects of potential MDR modulators combined with some anticancer drugs were also studied. Methods: Flow cytometry, MTT cytotoxicity assays and checkerboard combination assays were performed to study the reversal of drug resistance and to investigate the antiproliferative effects of the combination of anticancer drugs and the potential modulators. The results indicated that verapamil, capsanthin, zeaxanthin and promethazine inhibited P-gp effectively, but chrysin was not effective at reversing the resistance in MCF-7 sublines. Four selective anticancer drugs (paclitaxel, docetaxel, doxorubicin and vincristine) and 4 effective MDR modulators (verapamil, capsanthin, zeaxanthin and promethazine) were applied to the sublines in combination. Results and Conclusion: Fractional inhibitory indices show that verapamil and zeaxanthin seem to be the most effective MDR reversal agents that may be used together with paclitaxel, docetaxel, vincristine and doxorubicin in drug-resistant mammary carcinoma sublines. In conclusion, this report represents the importance to find out active and efficient drug resistance modulators for improving the efficacy of chemotherapy.

Design and synthesis of tetrahydroisoquinoline derivatives as potential multidrug resistance reversal agents in cancer

Exploration for new MDR-modulator utilizing tetrahydroisoquinoline as scaffold disclosed 6,7-dimethoxy-1-(3,4-dimethoxy)benzyl-2-( N- n-octyl- N′-cyano)guanyl-1,2,3,4-tetrahydroisoquinoline ( 7) as a readily accessible medicinal lead. Compound 7 possessed potent MDR reversal activity in the range of the reference compound verapamil, and had not cardiovascular activity compared to verapamil.

Limitation of multi-drug resistance reversal agents and study advance of new agents

The clinical application of multi-drug resistance reversal agents is greatly limited due to its severe side-effects and interference in pharmacokinetics of chemotherapeutic agents. Multi-drug resistance reversal agents haven' t been applicated in clinic successfully. The third generation multi- drug resistance reversal agents, including gefitinib and GF120918, etc, has promising prospect. Key words: Neoplasms ; Drug tolerance ; Carrier proteins

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

Fructus Schizandrae (FS) is commonly used as a tonic in traditional Chinese medicine. Recently, FS was found to significantly improve liver dysfunction in chronic hepatitis patients. The present study was to assess the reversal effect of five schizandrins and crude extract from FS (named LCC) on multidrug resistance (MDR) of cancer cells, both in vitro and in vivo. Chemically, the five schizandins are derivatives of dibenzo-(a, c)-cyclooctene lignan with distinct structures differing from any known MDR reversal agents. A panel of sensitive and resistant cancer cell lines were treated with various concentrations of LCC and schizandrins. Drug sensitivity, accumulation of Doxorubicin (Dox), expression of P-glycoprotein and protein kinase C (PKC), and apoptosis were determined in vitro. The in vivo effect was tested in nude mice grafted with sensitive and resistant human epidermal cancer cell line to vincristine (VCR) (KB, KBv200). The tested five compounds at 25 muM showed various levels of MDR reversal activity, of which, schizandrin A (Sin A) was the most potent one. Sin A reversed VCR resistance in KBv200 cells, MCF-7/Dox cells and Bel7402 cells by 309-, 38-, and 84-folds, respectively. Also, Sin A reversed the resistance of Dox in the above cancer cell lines. LCC at 25 mug/ml reversed VCR resistance by 619-folds in KBv200, 181-folds in MCF-7/Dox cell line, and 1,563-folds in innate resistance of human hepatic cellular carcinoma Bel7402 cells to VCR. Furthermore, LCC and its active component Sin A potently reversed the cross-resistance to paclitaxel in those cell lines. Both Sin A and LCC markedly increased intracellular Dox accumulation and enhanced apoptosis, down-regulated Pgp protein and mRNA and total PKC expression in MDR cells. Coadministration of LCC (p.o.) significantly potentiated the inhibitory effect of VCR (i.p.) on tumor growth in nude mice bearing KBv200 xenograft. The LCC and its active component Sin A have remarkable reversal effect on MDR in cancer cells by inhibition of both the function and expression of Pgp and total PKC.

Synthesis of curcumin mimics with multidrug resistance reversal activities

In order to discover novel multidrug resistance (MDR) reversal agents for efficient cancer chemotherapy, the unsymmetrical curcumin mimics with various amide moieties ( 6– 19) were synthesized and evaluated their MDR reversal activities in MDR cell line KBV20C. Among the tested compounds, 13, 16, and 17 showed potent MDR reversal activities by inhibiting drug efflux function of P-glycoprotein in KB20C cells, and almost recovered the cytotoxicity of vincristine and paclitaxel against KBV20C cell to the degree of potency against drug sensitive KB cells.

Lobeline, a piperidine alkaloid from Lobelia can reverse P-gp dependent multidrug resistance in tumor cells

Multidrug resistance (MDR) can limit efficacy of chemotherapy. The best studied mechanism involves P-gp (P-glycoprotein) mediated drug efflux. This study focuses on MDR reversal agents from medicinal plants, which can interfere with P-gp. Rhodamine 123 accumulation assay and flow cytometry analysis were employed to screen for P-gp dependant efflux inhibitors. Lobeline, a piperidine alkaloid from Lobelia inflata and several other Lobelia species, inhibited P-gp activity. MDR reversal potential of lobeline could be demonstrated in cells treated with doxorubicin in that lobeline can sensitize resistant tumor cells at non-toxic concentrations. However, lobeline cannot block BCRP (Breast Cancer Resistance Protein) dependent mitoxantrone efflux. Lobeline could be a good candidate for the development of new MDR reversal agents.

Biotransformation and tumor multidrug resistance reversal potency of polyoxygenated taxadienes

The biotransformation of four taxadienes, 2α,5α-diacetoxy-14β-hydroxy-10β-methoxytaxa-4(20),11(12)-diene ( 1), 10β-methoxy-2α,5α,14β-triacetoxytaxa-4(20),11(12)-diene ( 2), 2α,5α,10β-triacetoxytaxa-4(20),11(12)-dien-13-one ( 3), and 2α,5α-diacetoxy-10β-methoxytaxa-4(20),11(12)-dien-13-one ( 4) were individually investigated by the cultured cells of Ginkgo biloba. Six new metabolites together with four known metabolites were obtained from their biotransformations. Most compounds were evaluated for the MDR reversal activity against taxol-resistant human non-small cell lung cancer (NSCLC)-lung adenocarcinoma cell line, A549/taxol. Two compounds, 5 and 6, exhibited significant MDR reversal activity when co-administered with taxol at 5 μM. The result showed that the methoxyl group at C-10 and hydroxyl group at C-14 may be potential pharmacophores with taxadiene MDR reversal agents.

Synthesis and biological evaluation of tetrahydroisoquinoline derivatives as potential multidrug resistance reversal agents in cancer

Tetrahydroisoquinoline derivatives were synthesized and their multidrug resistance reversal activities were evaluated in vitro. The results showed that some of the synthetic compounds had higher multidrug resistance (MDR) reversal activities than verapamil.

Substituted tetrahydroisoquinoline compound B3 inhibited P-glycoprotein-mediated multidrug resistance in-vitro and in-vivo

P-glycoprotein (P-gp) mediated multidrug resistance (MDR) is one of the main obstacles in tumour chemotherapy. A promising approach to reverse MDR is the combined use of nontoxic and potent P-gp inhibitor with conventional anticancer drugs. We have examined the potential of a newly synthesized tetrahydroisoquinoline derivative B3 as a MDR-reversing agent. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to examine the effect of B3 on the cytotoxicity in K562/A02 and MCF-7/ADM cells caused by doxorubicin (adriamycin). Accumulation and efflux of P-gp substrate rhodamine123 in K562/A02 and primary cultured rat brain microvessel endothelial cells (RBMECs) were measured to evaluate the inhibitory effect of B3 on P-gp. The K562/A02 xenograft model in nude mice was established to examine MDR-reversing efficacy of B3 in-vivo. The results indicated that co-administration of B3 resulted in an increase on chemosensitivity of K562/A02 and MCF-7/ADM cells to doxorubicin in a dose-dependent manner. Rhodamine123 accumulation in K562/A02 cells and RBMECs were significantly enhanced after the incubation with various concentrations of B3. Furthermore, B3 inhibited the efflux of rhodamine123 from RBMECs. Co-administration of B3 with doxorubicin significantly decreased weight and volume of tumour in nude mice. In conclusion, B3 is a novel and potent MDR reversal agent with the potential to be an adjunctive agent for tumour chemotherapy.

Melanoma differentiation associated gene-7/interleukin-24 reverses multidrug resistance in human colorectal cancer cells

Overexpression of the multidrug resistance 1 (MDR1) gene, encoding P-glycoprotein (P-gp), facilitates resistance to diverse chemotherapeutic drugs and current P-gp inhibitors display high toxicity. We studied the effects of melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24), which exhibits cancer-specific apoptosis-inducing properties, in drug-sensitive (SW620) and drug-resistant (SW620/Dox) colorectal carcinoma cells. Adenovirus administered mda-7/IL-24, Ad.mda-7, effectively reversed resistance to doxorubicin-induced apoptosis in SW620/Dox cells by increased intracellular accumulation and decreased efflux of doxorubicin. Unexpectedly, P-gp-overexpressing cells (SW620/Dox) displayed increased apoptosis following Ad.mda-7 infection compared with parental SW620 cells, which correlated with more MDA-7/IL-24 protein in SW620/Dox than SW620 cell and potentially explains the increased sensitivity of P-gp-overexpressing cells to mda-7/IL-24. Transient overexpression of MDR1 in SW620 cells significantly increased apoptosis, decreased anchorage-independent growth, and increased MDA-7/IL-24 protein following Ad.mda-7 infection, whereas down-modulation of MDR1 in SW620/Dox cells by small interfering RNA decreased apoptosis following Ad.mda-7 infection. The increased mda-7/IL-24 sensitivity observed in SW620/Dox cells was partly due to increased reactive oxygen species generation and lower mitochondrial membrane potential. These findings confirm that mda-7/IL-24 is a potent MDR reversal agent, preferentially causing apoptosis in P-gp-overexpressing MDR cells, suggesting significant expanded clinical implications for the use of mda-7/IL-24 in treating neoplasms that have failed chemotherapy mediated by the P-gp MDR mechanism.

New terpenoids from Maytenus apurimacensis as MDR reversal agents in the parasite Leishmania

Two new sesquiterpenes ( 1– 2) and one new lupane triterpene ( 3) have been isolated from the roots of Maytenus apurimacensis. The novel β-dihydroagarofurans are the first sesquiterpenes with a basic polyhydroxy skeleton of 15-deoxyalatol and 4,15-dideoxyalatol that show high MDR reversing activity in the protozoan parasite Leishmania tropica.

Reversal effect of BM-cyclin 1 on multidrug resistance in C-A120 cells

In this study, multidrug-resistant human epidermoid C-A120 cells and the sensitive parental KB cells were used as experimental models. BM-cyclin 1, a traditional antimycoplasma drug, was tested to explore the reversal effect of multidrug resistance and its mechanisms in these cell lines. The MTT analysis showed that BM-cyclin 1 could reverse multidrug resistance effectively in C-A120 cells; the sensitivity of C-A120 cells to adriamycin, etoposide and cisplatin was enhanced by 6.0, 8.2 and 1.7 times, respectively. Immunoblotting analysis and reverse transcription-polymerase chain reaction were used to study the BM-cyclin 1-induced changes in topoisomerase IIalpha. The results showed that the expression of topoisomerase IIalpha in treated C-A120 cells increased significantly. Topoisomerase II catalytic activity increased by 30% compared with the untreated cells, as measured by decatenation of kinetopolast DNA. Immunoblotting analysis also indicated the transcription factor levels of specificity: those of protein 1 (Sp1) and nuclear factor-YA increased after treatment with BM-cyclin 1, whereas the mRNA and protein expression of multidrug resistance protein 2 was significantly downregulated. These results demonstrated that BM-cyclin 1 could effectively reverse the multidrug resistance of C-A120 cells by increasing the expression of topoisomerase IIalpha and by suppressing the expression of multidrug resistance protein 2, strongly suggesting that BM-cyclin 1 is a potential multidrug resistance reversal agent.

Polyoxyethylene 40 stearate modulates multidrug resistance and enhances antitumor activity of vinblastine sulfate

Multidrug resistance (MDR) is one of the major obstacles limiting the efficacy of cancer chemotherapy. Identification of new and effective MDR reversal agents is needed. In this study, the effects of polyoxyethylene 40 stearate (PS40) on MDR were evaluated via the transport of the P-glycoprotein (P-gp) substrate vinblastine sulfate (VBL) through Caco-2 cell monolayers and rat intestine tissue. The effects of PS40 on the antitumor activity of VBL were examined through 3-(4,5)-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay and multidrug-resistant tumor-bearing mice. Results of the transport experiments showed that PS40 reduced VBL efflux. The cytotoxicity of vinblastine to K562/ADR cells was significantly enhanced when the cells were cotreated with 100 or 150 microg/mL PS40. In vivo data revealed that average tumor volume and average tumor weight were significantly less in the VBL+PS40 group than in the VBL group. The inhibition rate for tumor growth was increased from 0.06 (VBL group) to 0.84 (VBL+PS40 group). These results suggest that PS40 may be a potentially useful adjuvant to enhance the therapeutic effects of P-gp substrates.

Drug Resistance in Melanoma: New Perspectives

Melanoma is the most aggressive form of skin cancer and advantages stages are inevitably resistant to conventional therapeutic agents. In particular, the inability of undergo apoptosis in response to chemotherapy and other external stimuli poses a selective advantage for tumor progression, metastasis formation as well as resistance to therapy in melanoma. Herein, we will review the discovery of MDR transporters and the apoptotic mechanisms used by melanoma cells. Furthermore, the novel strategies to overcome tumor chemoresistance will also discuss. In particular, we will review the cancer stem cell hypothesis and how the failure of MDR reversal agents might increase the therapeutic index of substrate antineoplastic agents.

New 1,3-dioxolane and 1,3-dioxane derivatives as effective modulators to overcome multidrug resistance

Multidrug resistance (MDR) to antitumor agents represents a major obstacle to a successful chemotherapy of cancer. Overexpression of P-glycoprotein (p-gp) seems to be the major factor responsible for MDR. A large number of chemically unrelated compounds are known to interact with p-gp resulting in a decreasing resistance. In our efforts related to structure–activity studies of new potential MDR reversal agents we synthesized a series of compounds that differ in the aromatic core structure, the linker, and the basic moiety. For our search of new aromatic core structures we synthesized novel 2,2-diphenyl-1,3-dioxolane, 2,2- diphenyl-1,3-dioxane, and 4,5-diphenyl-1,3-dioxolane derivatives. A range of lipophilic linker structures and protonable basic moieties were synthesized and investigated to optimize the structure of the potential MDR-modulators. The compounds were tested in vitro using human Caco-2 cells. Both the cytotoxicity of the synthons and their ability to resensitize the cells were determined with a MTT assay. The results show that at low concentration various substances reverse tumor cell MDR. Some of the new structures show better effects than established modulators like trifluoperazine.

Structure–activity relationships of some taxoids as multidrug resistance modulator

1,7-Deoxy-4-deacetylbaccatin III ( 12) and its five analogues 6– 9, 13, and their oxetane ring opened derivatives 14, 16, and 17, which were synthesized from taxinine, showed significant activity as MDR reversal agent by the assay of the calcein accumulation toward MDR human ovarian cancer 2780AD cells. The most effective compound 12 in this assay is actually efficient for the recovery of cytotoxic activity of paclitaxel (taxol ®), adriamycin (ADM), and vincristine (VCR) toward MDR 2780AD cells at the same level toward parental 2780 cells. This activity of 12 is very interesting because baccatin III ( 4) has no such MDR reversal activity but has cytotoxic activity. The essential functional groups inducing such a difference in biological activity between 4 and 12 are 4α-acetoxyl for 4 and 4α-hydroxyl for 12. In seven compounds possessing MDR reversal activity, compound 12 is the most desirable compound for anti-MDR cancer reversal agent, because it has the highest accumulation ability of anticancer agent in MDR cancer cells and weak cytotoxic activity. Compounds 8 and 13 showed significant cytotoxic activity toward HepG2 and VA-13, respectively, as well as MDR reversal activity. They are expected to become lead compounds for new types of anticancer agent or anti-MDR cancer agent.

Recent advances in P-gp-mediated MDR reversal mechanisms

Expression of the multidrug resistance (MDR) phenotype is responsible for chemotherapy failure in numerous cancers. Overexpression of mdr1 gene-encoded permeability glycoprotein (P-gp) is known to play a pivotal role in the development of this phenotype. The role of P-gp has been proposed as an important goal in the design of chemotherapy strategies. However, modulation of P-gp activity by chemotherapy has limited possibilities because of toxicity and poor specificity. In this article, we review the latest advancements in different potential P-gp-mediated MDR reversal mechanisms as well as the methods of evaluating MDR reversal activity, which would be helpful in finding novel MDR reversal agents (or chemosensitizers).

Research advancement of high-throughput analysis technology in tumor multidrug resistance and resistance reversal agent

高通量分析技术是近年来肿瘤研究新平台,肿瘤多药耐药(MDR)和耐药逆转药物研究在肿瘤化疗领域亟需解决.现综述基因芯片、蛋白质芯片、组织芯片三大高通量微阵列技术在肿瘤MDR机制、筛选耐药逆转靶点和逆转药物及指导临床个体化治疗等方面的应用。