Doxorubicin-resistant Human Myelogenous Leukemia Research Articles

Overexpression of tensin homolog deleted on chromosome ten (PTEN) by ciglitazone sensitizes doxorubicin-resistance leukemia cancer cells to treatment.

Overcoming multidrug resistance (MDR) is a final goal of various recent studies, in which combination of different compounds and conventional chemotherapeutics results in circumventing MDR and hence cancer progression. Therefore, we aimed to investigate the effects of peroxisome proliferator-activated receptors (PPARs)-γ on MDR in doxorubicin-resistant human myelogenous leukemia cells. The effect of doxorubicin on cell viability following treatment with ciglitazone was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The activity of P-glycoprotein (P-gp), as one of the membrane transporters, was determined by the rhodamine 123 (Rho 123) assay. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot were used for the measurement of P-gp, and tensin homolog deleted on chromosome ten (PTEN) expression at mRNA and protein, respectively. For evaluation of doxorubicin (DOX)-induced apoptosis by annexin V/PI staining was used. Ciglitazone significantly increases the cytotoxic effects of DOX. In addition, ciglitazone considerably decreased the expression levels and activity of P-gp in DOX-resistant K562 cells. Furthermore, upon the ciglitazone treatment, PTEN expression could be increased in K562/DOX cells in a PPARγ-dependent manner. Moreover, ciglitazone significantly enhanced DOX-induced apoptosis in K562/DOX cells. The combination treatment of K562/DOX leukemia cancer cells with doxorubicin and ciglitazone might be an effective strategy in inducing apoptosis and reversing developed MDR, and more importantly decreasing the adverse side effects of these agents.

Balaglitazone reverses P-glycoprotein-mediated multidrug resistance via upregulation of PTEN in a PPARγ-dependent manner in leukemia cells.

Multidrug resistance in tumor cells is still a big challenge in cancer treatment. Therefore, identification ofsafe and effective multidrug resistance-reversing compounds with minimal side effects is an important approach in cancer treatment. Here, we investigated the role and potential mechanisms of peroxisome proliferator-activated receptor γ in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. The effect of doxorubicin on cell viability following treatment with balaglitazone, a peroxisome proliferator-activated receptor γ agonist, was evaluated using trypan blue and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Rhodamine123 assay was used to determine the activity of two common drug efflux membrane transporters P-glycoprotein and multidrug resistance protein-1. P-glycoprotein, multidrug resistance protein-1, and phosphatase and tensin homolog deleted on chromosome 10 messenger RNA/protein expression levels were measured by quantitative reverse transcription polymerase chain reaction and western blot analyses. Annexin V/fluorescein isothiocyanate assay was also employed to investigate apoptosis. We showed that balaglitazone considerably enhanced the cytotoxicity of doxorubicin. Balaglitazone also significantly downregulated P-glycoprotein expression and activity in K562/DOX cells and reduced multidrug resistance through elevation of intracellular doxorubicin in cells. Furthermore, upon balaglitazone treatment, phosphatase and tensin homolog deleted on chromosome 10 expression could be restored in K562/DOX cells in a peroxisome proliferator-activated receptor γ-dependent manner. We concluded that peroxisome proliferator-activated receptor γ agonist, balaglitazone, could reverse multidrug resistance by inducing phosphatase and tensin homolog deleted on chromosome 10 and peroxisome proliferator-activated receptor/ phosphatase and tensin homolog deleted on chromosome 10 signaling pathway. These findings suggest that targeting peroxisome proliferator-activated receptor γ might serve as an effective approach for circumventing multidrug resistance in chemotherapy of cancerous patients.

Chemical constituents from Cicuta virosa Linnaeus and their reversal effects on doxorubicin-resistant human myelogenous leukemia (K562/A02) cells

Abstract Two new compounds, 11,11′-dimer of scopoletin ( 1 ) and 11- O - β -glucopyranosylhamaudol ( 2 ), together with seven known compounds were isolated and identified from the whole grass of Cicuta virosa . The chemical structures of the isolated compounds were elucidated using different spectroscopic methods. In addition, the chemical constituents were evaluated for multidrug resistance reversing activity towards doxorubicin-resistant K562/A02 cells. Compounds 1 , 8 , and 9 were endowed with remarkable MDR reversing effects.

BME, a novel compound of anthraquinone, down regulated P-glycoprotein expression in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells via generation of reactive oxygen species

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in tumor cells is still a main obstacle for the chemotherapeutic treatment of cancers. Thus, development of effective MDR reversing agents is an important approach in the clinic. The present study revealed that BME, a novel compound of anthraquinone, elevated intracellular accumulation of the P-gp substrates and reduced concentration resulting in 50% inhibition of cell growth (IC50) values for doxorubicin (DOX) in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. Further more, BME was also reported to down regulated P-gp expression accompanying with generation of nontoxic low level of intracellular reactive oxygen species (iROS) and activation of extracellular signal-regulated kinase (ERK)1/2 as well as c-JUN N-terminal kinase (JNK). However, treatment with N-acetyl-cysteine (NAC), U0216 and SP600125 almost abolished actions of the BME mentioned above. These results indicated that the effect of the BME on the P-gp may be involved in generation of nontoxic low level of iROS and activation of ERK1/2 or JNK, which suggested valuable clues to screen and develop P-gp reversing agents.

Interaction of CJY, an Isoflavone, with ATPase of P-glycoprotein in Doxorubicin-resistant Human Myelogenous Leukemia (K562/DOX) Cells

The previous study reported CJY, an isoflavone, can reverse P-glycoprotein (P-gp)-mediated multidrug-resistance (MDR) in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. This study will investigate the exact mechanism of CJY on P-gp. By assessment of ATPase activity, we gained further insight into the nature of the CJY interactions with P-gp. Kinetic studies on ATPase activity were applied to show the effects of Verapamil (Ver) on CJY-stimulated, CJX1 on Ver-stimulated, and CJX1 on CJY-stimulated P-gp ATPase activity. Furthermore, the combined effects of CJY with Ver, and CJY with CJX1 were also evaluated isobolographically in numerous fixed-ratio combinations of 1:1, 1:2, 1:4, 1:8, and 1:10. The results showed that basal P-gp ATPase activity was increased by CJY with half-maximal activity concentration (Km) of 2.9±0.3 μM and the maximal ATPase activity velocity (Vmax) of 265±21 nM · min-1 · mg-1. Kinetic studies on ATPase activity showed the effects of Verapamil (Ver) on CJY-stimulated, CJX1 on Ver-stimulated, and CJX1 on CJY-stimulated P-gp ATPase activity were all non-competitive inhibition, indicating that these substrates can simultaneously but independently bind to diverse sites on P-gp. The combined effects of CJY with Ver, and CJY with CJX1 show that mixtures of both drugs at these fixed-ratios displayed synergistic interactions. CJY, CJX1 and Ver bind P-gp on different sites. CJY could be applied combining with other P-gp inhibitors to get better reversal of multidrug resistance than it used alone.

Molecular mechanism study of chemosensitization of doxorubicin-resistant human myelogenous leukemia cells induced by a composite polymer micelle

The present study was aimed to overcome the multidrug resistance (MDR) of tumor cells which accounts for the failure of clinical chemotherapy. A novel doxorubicin (DOX)-loaded composite micelle consisting of polyethylene glycol (PEG)–polycaprolactone (PCL)/Pluronic P105 has been developed and was proved to inhibit the drug resistance of human myelogenous leukemia (K562/ADR) cells. The modulation mechanism that DOX-loaded the composite micelle inhibited MDR was for the first time investigated at cell levels. Results indicated that the cytotoxicity in K562/ADR cells treated by DOX-loaded PEG–PCL/P105 composite micelle was about 4 times higher than DOX solution at 12 μg/mL of DOX. Confocal images showed that the DOX-loaded composite micelles gradually entered into cytoplasm and nucleus, and stayed in intracellular much longer than DOX solution. All the micelles (PEG–PCL micelle, P105 micelle and PEG–PCL/P105 composite micelle) did not change Pgp expression on the surface of K562/ADR cells. However, further study revealed that micelle containing of P105 (P105 or PEG–PCL/P105 composite micelle) significantly decreased ATP level, and consequently restricted the activity of Pgp by down-regulation of mitochondrial membrane potential. On the other hand, the PEG–PCL micelle had no effect on both mitochondrial membrane potential and ATP level of the K562/ADR cells, but its access to K562/ADR cells through endocytic pathway avoided the recognition of Pgp. The PEG–PCL/P105 composite micelle was designed based on the combination of P105-mediated down regulation of mitochondrial membrane potential the malignant cells and PEG–PCL-mediated internalization effect. Therefore, the novel composite micelle is a promising drug delivery system for anticancer drug to overcome MDR.

The synergistic reversal effect of multidrug resistance by quercetin and hyperthermia in doxorubicin-resistant human myelogenous leukemia cells

Purpose: This study aimed to evaluate the multidrug resistance (MDR) reversal activity of quercetin (Que) in combination with hyperthermia (HT) in human myelogenous leukemia cells K562/A.Methods: The cytotoxicity of Que alone and the effect of Que and HT to doxorubicin (Dox) cytotoxicity were determined using MTT assay in K562 and K562/A cells. K562/A cells was heated with or without Que pretreatment, and the protein and mRNA levels of heat shock protein 70 (HSP70) and P-glycoprotein (P-gp) were determined by flow cytometry (FCM) and RT-PCR, respectively. Intracellular accumulation of Dox, cell cycle and apoptosis were monitored with FCM.Results: Que alone inhibited cell growth in a dose-dependent manner in K562 and K562/A cells. Either Que or HT alone had a weak reversal effect on Dox resistance, however, combination HT and Que showed a much more significant reversal effect on Dox resistance (reverse fold 9.49). The elevated protein expression and mRNA level of HSP70 and P-gp in response to HT were inhibited by Que. Pretreatment with Que caused the cells to accumulate Dox 8.3-fold higher than in control cells. In addition, Que induced apoptosis and G2/M arrest in a dose-dependent manner, and the combination of Que and HT was found to have a synergistic efeect on apoptosis.Conclusions: Que pretreatment could significantly inhance the MDR reversal activity of HT in resistant cell line, by sensitizing the cell to reversing MDR activity of HT.

CJX2, an amlodipine derivative, reverses p-glycoprotein-mediated multidrug-resistance in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells

P-glycoprotein-mediated drug efflux can yield a multidrug-resistance (MDR) phenotype that is associated with a poor response to cancer chemotherapy. Development of safe and effective MDR-reversing agents is an important approach in the clinic. The aim of this study was to observe the effects of CJX2, an amlodipine derivative, on the inhibition of P-gp function and P-gp-mediated MDR in K562/DOX cells and parental K562 cells. Based on the flow cytometric technology, the uptake, accumulation, and efflux of rhodamine123 (Rh123) were detected in these cells by measuring Rh123-associated mean fluorescence intensity (MFI). The effects of CJX2 on the doxorubicin cytotoxicity were evaluated by assaying for MTT (3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide) reduction and the reversal fold (RF) values. The DNA content, percentage of apoptosis, and cell cycle analysis were monitored with flow cytometry. Intracellular accumulation of doxorubicin was also assessed by the determination of doxorubicin-associated MFI. Verapamil was employed as a comparative agent. Incubation of K562/DOX cells with CJX2 caused a marked increase in accumulation, uptake, and a notable decrease in efflux of Rh123. No such results were found in parental K562 cells. The inhibitory effect of the agent on P-gp function was reversible, but it persisted at least for 90 min after removal of 2.5 µM CJX2 from incubation medium. The doxorubicin-induced cytotoxicity, apoptosis, and cell cycle perturbations were significantly potentiated by CJX2. The intracellular accumulation of doxorubicin was enhanced in the presence of various concentrations of CJX2. The CJX2 exhibited potent effects in vitro in the reversal of P-gp-mediated MDR, suggesting that the compound may become a candidate for an effective MDR-reversing agent in cancer chemotherapy. Drug Dev. Res. 66:278–285, 2006. © 2006 Wiley-Liss, Inc.

Reversal of p-glycoprotein-mediated multidrug resistance by CJX1, an amlodipine derivative, in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells

P-glycoprotein-mediated drug efflux can yield a multidrug resistance (MDR) phenotype that is associated with a poor response to cancer chemotherapy. Development of safe and effective MDR reversing agents is an important approach in the clinic. The aim of this study was to observe the effects of CJX1, an amlodipine derivative, on the inhibition of P-gp function and P-gp-mediated MDR in K562/DOX cells and parental K562 cells. Based on the flow cytometric technology, the uptake, accumulation and efflux of rhodamine123 (Rh123) were detected in these cells by measuring Rh123-associated mean fluorescence intensity (MFI). The effects of CJX1 on the doxorubicin cytotoxicity were evaluated by assaying for MTT (3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide) reduction and the reversal fold (RF) values. The DNA content, percentage of apoptosis and cell cycle analysis were monitored with flow cytometry. Intracellular accumulation of doxorubicin was also assessed by the determination of doxorubicin-associated MFI. Verapamil was employed as a comparative agent. Incubation of K562/DOX cells with CJX1 caused a marked increase in uptake and a notable decrease in efflux of Rh123, No such results were found in parental K562 cells. The inhibitory effect of the agent of P-gp function was reversible, but it persisted at least for 90 min after removal of 2.5 μM CJX1 from incubation medium. The doxorubicin-induced cytotoxicity, apoptosis and cell cycle perturbations were significantly potentiated by CJX1. The intracellular accumulation of doxorubicin was enhanced in the presence of various concentrations of CJX1. The CJX1 exhibited potent effects in vitro in the reversal of P-gp-mediated MDR, suggesting that the compound may become a candidate of effective MDR reversing agent in cancer chemotherapy.