Multiple drug resistance protein (MDR-1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) gene expression in childhood acute lymphoblastic leukemia

Overexpression of P-glycoprotein and MRP-1 are pharmacogenomic biomarkers to determine steroid resistant phenotype in childhood idiopathic nephrotic syndrome

Steroid remains the keystone therapy for Idiopathic Nephrotic Syndrome (NS). Besides genetic factors and histological changes, pharmacogenomic factors also affect the steroid response. The upregulation of P-glycoprotein (P-gp) and Multidrug resistance-associated protein 1 (MRP-1) modulate the pharmacokinetics of steroids and may contribute to steroid resistance. Flow-cytometric analysis of P-gp, MRP-1 expression and functional activity on peripheral blood mononuclear cells (PBMCs) was carried out in steroid-sensitive nephrotic syndrome (SSNS) (n = 171, male 103, mean age = 8.54 ± 4.3); and steroid-resistant nephrotic syndrome (SRNS) (n = 83, male 43, mean age = 7.43 ± 4.6) patients. The genotypings of MDR-1 gene were carried out using PCR-RFLP. We observed that the percentage expression of P-gp (10.01 ± 2.09 and 3.79 ± 1.13, p < 0.001); and MRP-1 (15.91 ± 3.99 and 7.40 ± 2.33, p < 0.001) on lymphocyte gated population were significantly higher in SRNS than that of SSNS. The functional activity of P-gp and MRP-1 was also significantly escalated in SRNS as compared to SSNS (68.10 ± 13.35 and 28.93 ± 7.57, p < 0.001); (72.13 ± 8.34 and 31.56 ± 8.65, p < 0.001) respectively. AUC-ROC curve analysis revealed that P-gp and MRP-1 expression with a cut-off value of 7.13% and 9.62% predicted SRNS with the sensitivity of 90% and 80.7%; and specificity 90% and 80%, respectively. Moreover, MDR-1 homozygous mutant TT+AA for G2677T/A (rs2032582) was significantly associated with SRNS (p = 0.025, OR = 2.86 CI = 1.14-7.14). The expression of P-gp (9.68 ± 4.99 v/s 5.88 ± 3.38, p = 0.002) was significantly higher in the patients of homozygous mutant alleles compared to wildtype GG. The increased expression and functionality of P-gp and MRP-1 contribute to steroid resistance, and MDR-1 homozygous mutant G2677T/A promotes steroid resistance by inducing P-gp expression in NS.

MicroRNA-18a-5p regulates the Warburg effect by targeting hypoxia-inducible factor 1α in the K562/ADM cell line

The Warburg effect is involved in drug resistance and recurrence of cancer, and poses a challenge for the treatment of chronic myelogenous leukemia (CML). Hypoxia-inducible factor 1α (HIF-1α) plays a key role in the Warburg effect. microRNAs (miRs) targeting HIF-1α have potential of regulating such aberrant metabolic process. The present study demonstrated that miR-18a-5p was expressed at a low level in K562/ADM cells via reverse transcription-quantitative PCR (RT-qPCR). The results of the luciferase reporter assay indicated that miR-18a-5p could specifically bind the 3'-untranslated region of HIF-1α. Through RT-qPCR and western blotting, it was revealed that miR-18a-5p downregulated the expression of HIF-1α. By inhibiting HIF-1α, miR-18a-5p suppressed aerobic glycolysis in K562/ADM cells, according to the results produced by glucose uptake, lactate production, pyruvate level and ATP synthesis measurement, along with the results obtained from extracellular acidification rate and oxygen consumption rate assays. These results provided new evidence that miR-18a-5p may suppress the Warburg effect by targeting HIF-1α. Furthermore, via CCK-8 and flow cytometry assays, cells transfected with miR-18a-5p mimics were more sensitive to Adriamycin (AMD) compared with AMD group. Reversing the Warburg effect by miR-30a-5p might provide a potential therapeutic strategy for CML.

Vault RNAs: hidden gems in RNA and protein regulation

Non-coding RNAs are important regulators of differentiation during embryogenesis as well as key players in the fine-tuning of transcription and furthermore, they control the post-transcriptional regulation of mRNAs under physiological conditions. Deregulated expression of non-coding RNAs is often identified as one major contribution in a number of pathological conditions. Non-coding RNAs are a heterogenous group of RNAs and they represent the majority of nuclear transcripts in eukaryotes. An evolutionary highly conserved sub-group of non-coding RNAs is represented by vault RNAs, named since firstly discovered as component of the largest known ribonucleoprotein complexes called "vault". Although they have been initially described 30 years ago, vault RNAs are largely unknown and their molecular role is still under investigation. In this review we will summarize the known functions of vault RNAs and their involvement in cellular mechanisms.

In vitro and ex vivo anti‑tumor effect and mechanism of Tucatinib in leukemia stem cells and ABCG2‑overexpressing leukemia cells

Leukemia stem cells (LSCs), which evade standard chemotherapy, may lead to chemoresistance and disease relapse. The overexpression of ATP-binding cassette subfamily G member 2 (ABCG2) is an important determinant of drug resistance in LSCs and it can serve as a marker for LSCs. Targeting ABCG2 is a potential strategy to selectively treat and eradicate LSCs, and, hence, improve leukemia therapy. Tucatinib (Irbinitinib) is a novel tyrosine kinase inhibitor, targeting ErbB family member HER2, and was approved by the Food and Drug Administration in April 2020, and in Switzerland in May 2020 for the treatment of HER2-positive breast cancer. In the present study, the results demonstrated that tucatinib significantly improved the efficacy of conventional chemotherapeutic agents in ABCG2-overexpressing leukemia cells and primary leukemia blast cells, derived from patients with leukemia. In addition, tucatinib markedly decreased the proportion of leukemia stem cell-like side population (SP) cells. In SP cells, isolated from leukemia cells, the intracellular accumulation of Hoechst 33342, which is an ABCG2 substrate, was significantly elevated by tucatinib. Furthermore, tucatinib notably inhibited the efflux of [³H]-mitoxantrone and, hence, there was a higher level of [³H]-mitoxantrone in the HL60/ABCG2 cell line. The result from the ATPase assay revealed that tucatinib may interact with the drug substrate-binding site and stimulated ATPase activity of ABCG2. However, the protein expression level and cellular location of ABCG2 were not affected by tucatinib treatment. Taken together, these data suggested that tucatinib could sensitize conventional chemotherapeutic agents, in ABCG2-overexpressing leukemia cells and LSCs, by blocking the pump function of the ABCG2 protein. The present study revealed that combined treatment with tucatinib and conventional cytotoxic agents could be a potential therapeutic strategy in ABCG2-positive leukemia.

Characterizing Iranian Pediatric Patients With Relapsed Acute Lymphoblastic Leukemia Through Gene Expression Profiling of Common ATP Binding Cassette Transporters Subfamily C

BACKGROUND

The correlation between gene expression of ABCC transporters and recurrence as a treatment failure in pediatric patients with acute lymphoblastic leukemia (ALL) is an unsolved problem in scientific associations. The aim of this study was to evaluate the predictive value of ABCC1-6 gene expression pattern for estimating recurrence in Iranian pediatric patients with ALL.

MATERIALS AND METHODS

Iranian pediatric patients with approved ALL enrolled in this study as 2 groups of case (relapsed ALL) and control (treated individuals who lasted for >3 years following their final treatment). Real-time polymerase chain reaction was done with GAPDH for expressing ABCC1-6 transporter genes. Cumulative doses of Vincristine, Daunorubicin, and L-Asparginase were checked for each patient. Gathered data analyzed with SPSS version 22 and REST 2009 software.

RESULTS

Thirty-nine samples as 23 relapsed ALL and 16 controls enrolled. High expression of ABCC2-6 and low expression of ABCC1 were detected in pediatric patients with relapse. ABCC3 and ABCC4 had significant relation with high-risk patients of NCI group. Also, ABCC4 and ABCC6 had more expression with high doses of Daunorubicin and L-Asparginase.

CONCLUSIONS

Designed expression pattern have the predictive value for estimating of conferring relapse in Iranian pediatric patients with diagnosed ALL. The authors suggest of designing a multiple childhood malignancy center project to evaluate this pattern in a cohort study.

Inorganic Nanoparticles as Drug Delivery Systems and Their Potential Role in the Treatment of Chronic Myelogenous Leukaemia

Chronic myeloid leukemia is a myeloproliferative disease where cells of myeloid linage display a t(9;22) chromosomal translocation leading to the formation of the BCR/ABL fusion gene and the continuous activation of tyrosine kinases. This malignancy has a peak incidence at 45 to 85 years, accounting for 15% of all leukemias in adults. Controlling the activity of tyrosine kinase became the main strategy in chronic myeloid leukemia treatment, with imatinib being placed at the forefront of current treatment protocols. New approaches in future anticancer therapy are emerging with nanomedicine being gradually implemented. Setting through a thorough survey of published literature, this review discusses the use of inorganic nanoparticles in chronic myeloid leukemia therapy. After an introduction on the basics of chronic myeloid leukemia, a description of the current treatment modalities of chronic myeloid leukemia and drug-resistance mechanisms is presented. This is followed by a general view on the applications of nanostrategies in medicine and then a detailed breakdown of inorganic nanocarriers and their uses in chronic myeloid leukemia treatment.

Structural Basis of Colchicine-Site targeting Acylhydrazones active against Multidrug-Resistant Acute Lymphoblastic Leukemia

Tubulin is one of the best validated anti-cancer targets, but most anti-tubulin agents have unfavorable therapeutic indexes. Here, we characterized the tubulin-binding activity, the mechanism of action, and the in vivo anti-leukemia efficacy of three 3,4,5-trimethoxy-N-acylhydrazones. We show that all compounds target the colchicine-binding site of tubulin and that none is a substrate of ABC transporters. The crystal structure of the tubulin-bound N-(1′-naphthyl)-3,4,5-trimethoxybenzohydrazide (12) revealed steric hindrance on the T7 loop movement of β-tubulin, thereby rendering tubulin assembly incompetent. Using dose escalation and short-term repeated dose studies, we further report that this compound class is well tolerated to >100 mg/kg in mice. We finally observed that intraperitoneally administered compound 12 significantly prolonged the overall survival of mice transplanted with both sensitive and multidrug-resistant acute lymphoblastic leukemia (ALL) cells. Taken together, this work describes promising colchicine-site-targeting tubulin inhibitors featuring favorable therapeutic effects against ALL and multidrug-resistant cells.

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3,4,5-trimethoxy-N-acylhydrazones bind to the colchicine site of tubulin

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12 forms a single H-bond with αThr179 and causes steric hindrance of tubulin βT7 loop

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3,4,5-trimethoxy-N-acylhydrazones feature low toxicity

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12 shows therapeutic effect against multidrug-resistant acute lymphoblastic leukemia

Sodium butyrate and panobinostat induce apoptosis of chronic myeloid leukemia cells via multiple pathways

Purpose

Histone deacetylase inhibitor (HDACI) is a novel therapeutic option for cancer. However, the effects of HDACIs on chronic myeloid leukemia (CML) and the underlying mechanisms are still unknown. The aim of this study was to investigate the effect and the mechanism‐of‐action of two HDACI members, sodium butyrate (NaBu) and panobinostat (LBH589) in K562 and the adriamycin–resistant cell line K562/ADR.

Methods

Cell viability was assessed using MTT assay. Cell apoptosis was detected with flow cytometry. Cell cycle analysis and western blot were performed to explore the possible molecules related to HDACIs effects.

Results

The effect of NaBu was more powerful on K562/ADR than on K562 cells. LBH589 triggered apoptosis and inhibited the growth of K562 cells. Both HDACIs inhibited K562 and K562/ADR cells via activation of intrinsic/extrinsic apoptotic pathways and inhibition of AKT‐mTOR pathway while NaBu also activated endoplasmic reticulum stress (ERS) mediated apoptotic pathway in K562/ADR cells. LBH589 reduced the expression of drug–resistant related proteins in K562 cells. However, neither NaBu nor LBH589 could significantly influence the expression of the drug–resistant related proteins in K562/ADR cells.

Conclusion

The combination of HDACI and other therapeutic strategies are likely required to overcome drug resistance in CML therapy.

Lung resistance-related protein (LRP) predicts favorable therapeutic outcome in Acute Myeloid Leukemia

There is conflicting evidence that MDR1, MRP2 and LRP expression is responsible for chemotherapy resistance. We conducted this study to explore their role in AML therapy outcomes. Bone marrow and peripheral blood samples of 90 AML patients, receiving chemotherapy, were analyzed by real time PCR. Gene expression was calculated by the 2-ΔΔCt method. The patients who had a persistent remission were labelled 'Good Responder' (GRes) whereas, those with relapse or drug resistance were labelled 'Poor Responders' (PRes). Higher LRP expression in bone marrow, but not in peripheral blood, was positively associated with persistent remission (p = 0.001), GRes (p = 0.002), 1-year overall as well as disease-free survival (p = 0.02 and p = 0.007, respectively). Marrow and blood MDR1 and MRP2 expression did not differ significantly between the above groups. Logistic regression analysis showed that only a diagnosis of acute promyelocytic leukemia (APL; M3) or high marrow LRP expression significantly predicted a favorable therapeutic outcome. This is the first report showing that high bone marrow LRP expression predicts significant favorable therapeutic outcome. Peripheral blood LRP expression as well as marrow and blood MDR1 and MRP2 expression have no predictive value in AML patients treated with standard dose cytarabine and daunorubicin 3+7 regimen.

P-glycoprotein Activity Correlates With Treatment Response in 2 Leukemia Child Patients

Acute lymphoblastic leukemia is the most important childhood cancer. Multidrug resistance is an important factor of poor prognosis. We present the P-glycoprotein (P-gp) activity in 2 patients with different outcomes. Both patients had B-cell acute lymphoblastic leukemia; they were responding properly to the treatment, but one of them had an increment in the P-gp activity that correlates with an increment in the disease manifestation, the patient had to be hospitalized and developed sepsis and subsequently died. P-gp levels were correlated with disease progression. P-gp activity needs to be evaluated during treatment to assess and prevent disease relapse or the patient´s death.

Effects of Clostridium difficile toxin A on K562/A02 cell proliferation, apoptosis and multi-drug resistance

The aim of the present study was to investigate the cytotoxic effect and multi-drug resistance (MDR) of Clostridium difficile toxin A (TcdA) on K562/A02 cells, and understand its underlying molecular pathways. K562/A02 cells were treated with TcdA at different concentrations for 24, 48 and 72 h, and the inhibition effect and drug resistance of TcdA on K562/A02 cell proliferation was assessed by methyl thiazolyl tetrazolium colorimetric assay. Furthermore, cell cycle-apoptosis was analyzed by flow cytometry, P-glycoprotein (P-gp) expression was determined by western blot analysis and caspase-3 activity was measured using a caspase-3 activity kit. TcdA inhibited K562/A02 cell proliferation in a time- and dose-dependent manner. The inhibition rate of K562/A02 cells reached 8.76±0.76, 28.55±0.43, 47.89±0.27, 58.08±0.06 and 57.70±0.79% following treatment with 50, 100, 200, 400 and 800 ng/ml TcdA, respectively, for 24 h. K562/A02 cells in the G0/G1 phase increased and cells in the S phase decreased following treatment with TcdA (P<0.05), and the apoptotic rates in the 200 and 400 ng/ml concentration groups were 14.05 and 22.89%, respectively. In addition, TcdA (50 ng/ml) significantly inhibited the proliferation of K562/A02 cells and reduced the half maximal inhibitory concentration of these drugs in combination with chemotherapy drugs. The reversal folds were 3.09, 2.89 and 2.79, respectively. Furthermore, TcdA treatment was associated with the upregulation of P-gp in K562/A02 cells, and caspase-3 activity was observed to increase in K562/A02 cells following TcdA treatment, when compared with untreated controls (P<0.05). These findings suggested that TcdA may be able to inhibit K562/A02 cell growth, induce cell apoptosis by decreasing P-gp levels and caspase-3 activation, and partially reverse MDR. Further studies are required to evaluate the potential of TcdA as a candidate for the chemotherapy of hematologic malignancies.

Expression of multidrug resistance proteins in retinoblastoma

AIM

To elucidate the mechanism of multidrug resistance in retinoblastoma, and to acquire more insights into in vivo drug resistance.

METHODS

Three anticancer drug resistant Y79 human RB cells were generated against vincristine, etoposide or carboplatin, which are used for conventional chemotherapy in RB. Primary cultures from enucleated eyes after chemotherapy (PCNC) were also prepared. Their chemosensitivity to chemotherapeutic agents (vincristine, etoposide and carboplatin) were measured using MTT assay. Western blot analysis was performed to evaluate the expression of p53, Bcl-2 and various multidrug resistant proteins in retinoblastoma cells.

RESULTS

Following exposure to chemotherapeutic drugs, PCNC showed less sensitivity to drugs. No significant changes observed in the p53 expression, whereas Bcl-2 expression was found to be increased in the drug resistant cells as well as in PCNC. Increased expression of P-glycoprotein (P-gp) was observed in drug resistant Y79 cells; however there was no significant change in the expression of P-gp found between primary cultures of primarily enucleated eyes and PCNC. Multidrug resistance protein 1 (Mrp-1) expression was found to be elevated in the drug resistant Y79 cells as well as in PCNC. No significant change in the expression of lung resistance associated protein (Lrp) was observed in the drug resistant Y79 cells as well as in PCNC.

CONCLUSION

Our results suggest that multidrug resistant proteins are intrinsically present in retinoblastoma which causes treatment failure in managing retinoblastoma with chemotherapy.

Multidrug resistance gene 1 polymorphisms in pediatric patients with leukemia at a national referral hospital in Indonesia

Background

Acute lymphoblastic leukemia (ALL) is the most prevalent cancer in the pediatric population. From 25% to 30% of patients with ALL will have a relapse that leads to death when they are teenagers. At Cipto Mangunkusumo Hospital, 40% of 126 pediatric patients with ALL relapsed from 2005 to 2011. A multiple variant of multidrug resistance gene 1 (MDR1) is C3435T, which can be used to understand the genetic basis of susceptibility to relapse.

Objectives

To identify the profile of MDR1 polymorphism in pediatric Indonesian patients with ALL.

Methods

We collected data from 44 patients with ALL who attended Cipto Mangunkusumo Hospital between January and June 2014. We investigated a silent C3435T polymorphism in MDR1 exon 26 with polymerase chain reaction- restriction fragment length polymorphism using MboI.

Results

There were 32 male and 12 female patient participants in this study. Eighteen patients were 1–3 years old and 26 were over 3 years. The mean age at 1–3 years was 2.4 ± 0.86, and over 3 years it was 6.3 ± 2.67 years. There were 27 patients with ALL in the standard risk group and 17 in the high risk group. We determined that the 25 samples from patients with ALL in the standard risk group were not digestible (allele T) and the 6 samples from patients with ALL in the high risk group were digestible (allele C).

Conclusions

The prevalence of the T allele was higher than that of the C allele in pediatric Indonesian patients with ALL.

Clinical significance of the ABCB1 and ABCG2 gene expression levels in acute lymphoblastic leukemia

OBJECTIVES

Acute lymphoblastic leukemia (ALL) is a clonal disease that accounts for 20% of acute leukemias in adults. A high percentage of adult patients (ranging from 70 to 80%) reach complete remission; however, the 5-year survival rate is only 20-40%. One of the main obstacles to treatment success is the drug resistance of leukemic cells. Therefore, our research group analyzed the ABCB1 and ABCG2 gene expression levels in 61 patients diagnosed with ALL and assessed whether the levels affected the clinical parameters and 40-month survival rate.

METHODS

The ABCB1 and ABCG2 gene expression levels were analyzed using real-time polymerase chain reaction in 61 patients diagnosed with ALL and 99 healthy donors as controls. The association between ABCB1 and ABCG2 gene expression levels and clinical variables was determined using the Chi-square test and Fisher's exact test. Overall survival (OS) was determined using the Kaplan-Meier method.

RESULTS

The results showed high ABCB1 and ABCG2 gene levels, which were 4.5 and 2.3 times the levels of healthy donors, respectively. A total of 52% of the study patients expressed high ABCB1 levels and were significantly associated with the high-risk patient group and a decreased 40-month survival rate of 78%. Only 49% of the patients expressed high ABCG2 gene levels. No association was found between the clinical parameters and the ABCG2 gene expression levels.

CONCLUSIONS

Early detection of ABCB1 gene expression levels could be important for the diagnosis and monitoring of ALL patients.

Oncolytic virus efficiency inhibited growth of tumour cells with multiple drug resistant phenotype in vivo and in vitro

Background

Tumour resistance to a wide range of drugs (multiple drug resistant, MDR) acquired after intensive chemotherapy is considered to be the main obstacle of the curative treatment of cancer patients. Recent work has shown that oncolytic viruses demonstrated prominent potential for effective treatment of diverse cancers. Here, we evaluated whether genetically modified vaccinia virus (LIVP-GFP) may be effective in treatment of cancers displaying MDR phenotype.

Methods

LIVP-GFP replication, transgene expression and cytopathic effects were analysed in human cervical carcinomas KB-3-1 (MDR−), KB-8-5 (MDR+) and in murine melanoma B-16 (MDR−), murine lymphosarcomas RLS and RLS-40 (MDR+). To investigate the efficacy of this therapy in vivo, we treated immunocompetent mice bearing murine lymphosarcoma RLS-40 (MDR+) (6- to 8-week-old female CBA mice; n = 10/group) or melanoma B-16 (MDR−) (6- to 8-week-old female C57Bl mice; n = 6/group) with LIVP-GFP (5 × 10⁷ PFU of virus in 0.1 mL of IMDM immediately and 4 days after tumour implantation).

Results

We demonstrated that LIVP-GFP replication was effective in human cervical carcinomas KB-3-1 (MDR−) and KB-8-5 (MDR+) and in murine melanoma B-16 (MDR−), whereas active viral production was not detected in murine lymphosarcomas RLS and RLS-40 (MDR+). Additionally, it was found that in tumour models in immunocompetent mice under the optimized regimen intratumoural injections of LIVP-GFP significantly inhibited melanoma B16 (33 % of mice were with complete response after 90 days) and RLS-40 tumour growth (fourfold increase in tumour doubling time) as well as metastasis.

Conclusion

The anti-tumour activity of LIVP-GFP is a result of direct oncolysis of tumour cells in case of melanoma B-16 because the virus effectively replicates and destroys these cells, and virus-mediated activation of the host immune system followed by immunologically mediated destruction of of tumour cells in case of lymphosarcoma RLS-40. Thus, the recombinant vaccinia virus LIVP-GFP is able to inhibit the growth of malignant cells with the MDR phenotype and tumour metastasis when administered in the early stages of tumour development.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1002-x) contains supplementary material, which is available to authorized users.

High Expression of Lung Resistance Protein mRNA at Diagnosis Predicts Poor Early Response to Induction Chemotherapy in Childhood Acute Lymphoblastic Leukemia

BACKGROUND

Treatment failure in leukemia is due to either pharmacokinetic resistance or cell resistance to drugs.

MATERIALS AND METHODS

Gene expression of multiple drug resistance protein (MDR-1), multidrug resistance-related protein (MRP) and low resistance protein (LRP) was assessed in 45 pediatric ALL cases and 7 healthy controls by real time PCR. The expression was scored as negative, weak, moderate and strong.

RESULTS

The male female ratio of cases was 2.75:1 and the mean age was 5.2 years. Some 26/45 (58%) were in standard risk, 17/45(38%) intermediate and 2/45 (4%) in high risk categorie, 42/45 (93%) being B-ALL and recurrent translocations being noted in 5/45 (11.0%). Rapid early response (RER) at day 14 was seen in 37/45 (82.3%) and slow early response (SER) in 8/45 (17.7%) cases. Positive expression of MDR-1, LRP and MRP was noted in 14/45 (31%), 15/45 (33%) and 27/45 (60%) cases and strong expression in 3/14 (21%), 11/27 (40.7%) and 8/15 (53.3%) cases respectively. Dual or more gene positivity was noted in 17/45 (38%) cases. 46.5 % (7/15) of LRP positive cases at day 14 were in RER as compared to 100% (30/30) of LRP negative cases (p<0.05). All 8 (100%) LRP positive cases in SER had strong LRP expression (p=<0.05). Moreover, only 53.3% of LRP positive cases were in haematological remission at day 30 as compared to 100% of LRP negative cases (p=<0.05).

CONCLUSIONS

Our study indicated that increased LRP expression at diagnosis in pediatric ALL predicts poor response to early treatment and hence can be used as a prognostic marker. However, larger prospective studies with longer follow up are needed, to understand the clinical relevance of drug resistance proteins.

Quantitative and qualitative analysis of small RNAs in human endothelial cells and exosomes provides insights into localized RNA processing, degradation and sorting

Exosomes are small vesicles that mediate cell-cell communication. They contain proteins, lipids and RNA, and evidence is accumulating that these molecules are specifically sorted for release via exosomes. We recently showed that endothelial-cell-produced exosomes promote angiogenesis in vivo in a small RNA-dependent manner. Recent deep sequencing studies in exosomes from lymphocytic origin revealed a broad spectrum of small RNAs. However, selective depletion or incorporation of small RNA species into endothelial exosomes has not been studied extensively. With next generation sequencing, we identified all known non-coding RNA classes, including microRNAs (miRNAs), small nucleolar RNAs, yRNAs, vault RNAs, 5p and 3p fragments of miRNAs and miRNA-like fragments. In addition, we mapped many fragments of messenger RNAs (mRNAs) and mitochondrial RNAs (mtRNAs). The distribution of small RNAs in exosomes revealed a considerable overlap with the distribution in the producing cells. However, we identified a remarkable enrichment of yRNA fragments and mRNA degradation products in exosomes consistent with yRNAs having a role in degradation of structured and misfolded RNAs in close proximity to endosomes. We propose that endothelial endosomes selectively sequester cytoplasmic RNA-degrading machineries taking part in gene regulation. The release of these regulatory RNAs via exosomes may have implications for endothelial cell-cell communication.

Overcoming multiple drug resistance mechanisms in medulloblastoma

INTRODUCTION

Medulloblastoma (MB) is the most common malignant paediatric brain tumour. Recurrence and progression of disease occurs in 15-20% of standard risk and 30-40% of high risk patients. We analysed whether circumvention of chemoresistance pathways (drug export, DNA repair and apoptotic inhibition) can restore chemotherapeutic efficacy in a panel of MB cell lines.

RESULTS

We demonstrate, by immunohistochemistry in patient tissue microarrays, that ABCB1 is expressed in 43% of tumours and is significantly associated with high-risk. We show that ABCB1, O6-methylguanine-DNA-methyltransferase (MGMT) and BCL2 family members are differentially expressed (by quantitative reverse transcription polymerase chain reaction, Western blotting and flow cytometry) in MB cell lines. Based on these findings, each pathway was then inhibited or circumvented and cell survival assessed using clonogenic assays. Inhibition of ABCB1 using vardenafil or verapamil resulted in a significant increase in sensitivity to etoposide in ABCB1-expressing MB cell lines. Sensitivity to temozolomide (TMZ) was MGMT-dependent, but two novel imidazotetrazine derivatives (N-3 sulfoxide and N-3 propargyl TMZ analogues) demonstrated ≥7 fold and ≥3 fold more potent cytotoxicity respectively compared to TMZ in MGMT-expressing MB cell lines. Activity of the BAD mimetic ABT-737 was BCL2A1 and ABCB1 dependent, whereas the pan-BCL2 inhibitor obatoclax was effective as a single cytotoxic agent irrespective of MCL1, BCL2, BCL2A1, or ABCB1 expression.

CONCLUSIONS

ABCB1 is associated with high-risk MB; hence, inhibition of ABCB1 by vardenafil may represent a valid approach in these patients. Imidazotetrazine analogues of TMZ and the BH3 mimetic obatoclax are promising clinical candidates in drug resistant MB tumours expressing MGMT and BCL2 anti-apoptotic members respectively.

mRNA expression profile of multidrug-resistant genes in acute lymphoblastic leukemia of children, a prognostic value for ABCA3 and ABCA2

Multidrug resistance (MDR) is an important cause of treatment failure in acute lymphoblastic leukemia (ALL). The ABC family of membrane transporters is proposed, albeit with controversy, to be involved in this process. The present study aims to investigate the mRNA expression profile of several genes of this family, including ABCA2, ABCA3, ABCB1/MDR1, MRP1/ABCC1, MRP3/ABCC3, ABCG2/BCRP, and the intracellular transporter MVP/LRP, in childhood ALL, and to evaluate their association with response to therapy. Some genes in the present research are being studied for the first time in Iran. Using quantitative real-time PCR, we evaluated 27 children with ALL at diagnosis and 15 children with normal bone marrow. The status of response to therapy was assessed one year after the onset of therapy through investigating the IgH/TCRγ gene rearrangements. Our findings indicate a considerable and direct relationship between mRNA expression levels of ABCA2, ABCA3, MDR1, and MRP1 genes and positive minimal residual disease (MRD) measured after one year of treatment. Statistical analysis revealed that expression of these genes higher than the cutoff point will raise the risk of MRD by 15-, 6.25-, 12-, and 9-fold, respectively. No relationship was found between of MVP/LRP, MRP3 and ABCG2 genes expression and ALL prognoses. Considering the direct and significant relationship between the increased expression of ABCA2, ABCA3, MDR1, and MRP1 genes and positive risk of MRD in children with ALL, evaluating the expression profile of these genes on diagnosis may identify high risk individuals and help plan a more efficient treatment strategy.

Importance of detecting multidrug resistance proteins in acute leukemia prognosis and therapy

Multidrug resistance (MDR) is a multifactorial phenomenon and the role of these proteins in generating the MDR phenotype is controversial. With this in mind, this review compiled the current data on the role of ABCB1, ABCC1, and LRP proteins in the prognosis of hematologic neoplasms and their influence on the choice of therapy. Literature showed that the detection of these proteins, mainly ABCB1, is important in the AL prognosis. However, there is controversy regarding the methodology used for their detection. In summary, the expression and activity profiles of ABCB1, ABCC1, and LRP, proteins capable of promoting the efflux of a variety of chemotherapeutic agents from the cell cytoplasm represent one of the greatest causes of failure in AL treatment.

Regulation of expression of ABCB1 and LRP genes by mitogen-activated protein kinase/extracellular signal-regulated kinase pathway and its role in generation of side population cells in canine lymphoma cell lines

The concept of the cancer stem cell (CSC) has been recognized as key for elucidation of the mechanisms that confer the multidrug resistance (MDR) phenotype to tumor cells, and the side population (SP) fraction has been shown to be enriched by cells with the CSC phenotype. The purpose of the present study was to identify the mechanism that induces a difference of phenotype between the SP and the remaining major population (MP) using two canine lymphoma cell lines. Expression levels of ABCB1 and LRP genes, which encode efflux pumps, were significantly higher in the SP than in the MP. Microarray analysis revealed up-regulation of the expression of transforming growth factor-β (TGF-β) type II receptor in SP compared with MP, and the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway was more up-regulated in the SP than in the MP. Stimulation of the MAPK/ERK pathway significantly increased the mRNA expression of both ABCB1 and LRP genes. These results indicate increased expression of the efflux pumps through the MAPK/ERK pathway in SP cells.

Evaluation of multidrug resistance in 46 newly diagnosed patients with acute leukemia

OBJECTIVES

The aim of the present study was to assess the expression profile of multidrug resistance (MDR)-related proteins ABCB1, ABCC1 and LRP in 46 patients with acute leukemia (AL).

METHODS

The levels of MDR gene mRNA expression and protein expression at diagnosis were analyzed by semi-quantitative PCR and flow cytometry, respectively.

RESULTS

In the adult group, higher expression levels of abcc1 gene were associated with older age and lower levels of lactate dehydrogenase (LDH). In the pediatric group, abcc1 gene expression levels were associated with higher CD34 expression and a higher ABCB1 protein expression was correlated with high WBC counts.

DISCUSSION/CONCLUSION

The present data indicate that abcb1 gene overexpression may be associated with a poor prognosis in adults with AL and that ABCB1 and abcc1 expression correlates with different prognostic factors in pediatric patients with AL. Our findings demonstrate that the method of choice to evaluate chemotherapy resistance-related proteins is a major variable.

Gene polymorphisms of ABC transporters are associated with clinical outcomes in children with acute lymphoblastic leukemia

INTRODUCTION

Genetic variability affects clinical outcome in pediatric acute lymphocytic leukemia (ALL) patients. Evaluating gene polymorphisms in ABC transporters could help identify relapse risk and predict outcome.

MATERIAL AND METHODS

The SNaPshot SNP technique was used to analyze single-nucleotide polymorphisms (SNPs) in the multidrug transporter 1 (MDR1), multidrug resistance associated proteins (MRP1, MRP2) and breast cancer resistance protein (BCRP) genes of 82 pediatric ALL patients. The association between the SNPs with risk of all events and death as well as with survival was evaluated by the univariate Cox proportional hazard model.

RESULTS

The BCRP G34A SNP was the only SNP significantly associated with ALL. Risk factors included pre-treatment WBC counts and post-treatment peripheral and bone marrow leukemic cell counts. We found no association between MDR1 SNPs with these factors. The BCRP C421A C/A and C/C genotypes were significantly associated with low pre-treatment WBC counts while MRP2 G1249A G/G was significantly associated with low levels of post-treatment peripheral and bone marrow leukemic cells. A combination of C1236T, G1249A and/or G34A SNPs was significantly associated with lower EFS and OS.

CONCLUSIONS

Polymorphisms associated with risk of ALL and clinical outcome may be potential biomarkers to predict clinical outcome and improve prognosis in childhood ALL.

MVP and vaults: a role in the radiation response

Vaults are evolutionary highly conserved ribonucleoproteins particles with a hollow barrel-like structure. The main component of vaults represents the 110 kDa major vault protein (MVP), whereas two minor vaults proteins comprise the 193 kDa vault poly(ADP-ribose) polymerase (vPARP) and the 240 kDa telomerase-associated protein-1 (TEP-1). Additionally, at least one small and untranslated RNA is found as a constitutive component. MVP seems to play an important role in the development of multidrug resistance. This particle has also been implicated in the regulation of several cellular processes including transport mechanisms, signal transmission and immune responses. Vaults are considered a prognostic marker for different cancer types. The level of MVP expression predicts the clinical outcome after chemotherapy in different tumour types. Recently, new roles have been assigned to MVP and vaults including the association with the insulin-like growth factor-1, hypoxia-inducible factor-1alpha, and the two major DNA double-strand break repair machineries: non-homologous endjoining and homologous recombination. Furthermore, MVP has been proposed as a useful prognostic factor associated with radiotherapy resistance. Here, we review these novel actions of vaults and discuss a putative role of MVP and vaults in the response to radiotherapy.

Lentinan enhances cisplatin-mediated inhibition of cell proliferation in human gastric cancer cell line SGC-7901

AIM: To investigate whether lentinan enhances cisplatin-mediated inhibition of cell proliferation in human gastric cancer cell line SGC-7901 and to explore its effect on the expression of multidrug resistance genes.

METHODS: SGC-7901 cells were divided into four groups: untreated cells (control group), those treated with lentinan alone (lentinan group), those treated with cisplatin alone (cisplatin group), and those treated with both lentinan and cisplatin (lentinan + cisplatin group). RT-PCR was applied to detect the mRNA expression of MDR1, MRP1, and LRP in SGC-7901 cells. The proliferation of SGC-7901 cells was detected using the Cell Counting Kit-8.

RESULTS: High expression of multidrug resistance genes MDR1, MRP1 and LRP was detected in untreated SGC-7901 cells. Treatment with lentinan significantly decreased the mRNA expression of multidrug resistance genes but had no effect on cell proliferation (P > 0.05). Cisplatin treatment lessened cell proliferation and promoted the expression of multidrug resistance genes. Treatment with lentinan + cisplatin completely suppressed the mRNA expression of MDR1 and MRP1 and significantly decreased LRP expression and cell proliferation compared with the control group, lentinan group, and cisplatin group (10 d: 0.54 vs 1.90, 1.88, 0.92, all P < 0.05).

CONCLUSION: Lentinan combined with cisplatin can significantly inhibit the expression of multidrug resistance genes and strongly enhance cisplatin-mediated inhibition of the proliferation of SGC-7901 cells.

Update information on drug metabolism systems--2009, part II: summary of information on the effects of diseases and environmental factors on human cytochrome P450 (CYP) enzymes and transporters

The present paper is an update of the data on the effects of diseases and environmental factors on the expression and/or activity of human cytochrome P450 (CYP) enzymes and transporters. The data are presented in tabular form (Tables 1 and 2) and are a continuation of previously published summaries on the effects of drugs and other chemicals on CYP enzymes (Rendic, S.; Di Carlo, F. Drug Metab. Rev., 1997, 29(1-2), 413-580., Rendic, S. Drug Metab. Rev., 2002, 34(1-2), 83-448.). The collected information presented here is as stated by the cited author(s), and in cases when several references are cited the latest published information is included. Inconsistent results and conclusions obtained by different authors are highlighted, followed by discussion of the major findings. The searchable database is available as an Excel file, for information about file availability contact the corresponding author.

Mechanisms of multidrug resistance in cancer

The development of multidrug resistance (MDR) to chemotherapy remains a major challenge in the treatment of cancer. Resistance exists against every effective anticancer drug and can develop by numerous mechanisms including decreased drug uptake, increased drug efflux, activation of detoxifying systems, activation of DNA repair mechanisms, evasion of drug-induced apoptosis, etc. In the first part of this chapter, we briefly summarize the current knowledge on individual cellular mechanisms responsible for MDR, with a special emphasis on ATP-binding cassette transporters, perhaps the main theme of this textbook. Although extensive work has been done to characterize MDR mechanisms in vitro, the translation of this knowledge to the clinic has not been crowned with success. Therefore, identifying genes and mechanisms critical to the development of MDR in vivo and establishing a reliable method for analyzing clinical samples could help to predict the development of resistance and lead to treatments designed to circumvent it. Our thoughts about translational research needed to achieve significant progress in the understanding of this complex phenomenon are therefore discussed in a third section. The pleotropic response of cancer cells to chemotherapy is summarized in a concluding diagram.

Expression of lung resistance protein and multidrug resistance-related protein (MRP1) in pediatric acute lymphoblastic leukemia

Multidrug resistance (MDR) is a phenomenon by which cells become resistant to unrelated chemotherapeutic agents. The prognostic value that lung resistance protein (LRP) and multidrug resistance-related protein 1 (MRP1) have in the setting of pediatric acute lymphoblastic leukemia (ALL) is controversial. The aim of this study was to investigate the expression of LRP and MRP1 and effect on clinical outcome and prognosis. The mRNA expression of LRP and MRP1 were analyzed in leukemic blasts of 34 pediatric ALL patients. LRP and MRP1 mRNA expression were detected in 41.2% and 35.3%, respectively. Eleven (91.7%) of 12 patients without LRP achieved CR compared with 9 (50.0%) of 18 with LRP expression. Similarly, 11 (100%) of 11 patients without MRP1 expression achieved CR compared with 9 (47.4%) of 19 with MRP1 expression and higher LRP expression rate or MRP1 expression rate was present in patients with relapse than MDR genes negative patients. The expression of either of two genes was associated with poorer 2-year survival. Also, patients expressing both genes had poorer outcomes and had worse 2-year survival. We suggest that MDR expression affects complete remission and survival rates in ALL patients. Thus, diagnosis appears to provide prognostic information for pediatric ALL.

mRNA expression profile of multidrug resistance genes in childhood acute lymphoblastic leukemia. Low expression levels associated with a higher risk of toxic death

BACKGROUND

Increased activity of multidrug resistance (MDR) genes has been associated with treatment failure in acute leukemias, although with controversial reports. The objective of the present study was to assess the expression profile of the genes related to MDR: ABCB1, ABCC1, ABCC3, ABCG2, and LRP/MVP in terms of the clinical and biological variable and the survival of children with acute lymphoblastic leukemia (ALL).

PROCEDURE

The levels of mRNA expression of the drug resistance genes ABCB1, ABCC1, ABCC3, ABCG2, and LRP/MVP were analyzed by quantitative real-time PCR using the median values as cut-off points, in consecutive samples from 140 children with ALL at diagnosis.

RESULTS

Expression levels of the ABCG2 gene in the patient group as a whole (P = 0.05) and of the ABCG2 and ABCC1 genes in patients classified as being at high risk were associated with higher rates of 5-year event-free survival (EFS) (P = 0.04 and P = 0.01). Expression levels of the ABCG2 gene below the median were associated with a greater chance of death related to treatment toxicity for the patient group as a whole (P = 0.009) and expression levels below the median of the ABCG2 and ABCC1 genes were associated with a greater chance of death due to treatment toxicity for the high-risk group (P = 0.02 and P = 0.03, respectively).

CONCLUSION

The present data suggest a low participation of the drug efflux genes in treatment failure in patients with childhood ALL. However, the low expression of some of these genes may be associated with a higher death risk related to treatment toxicity.

Effect of magnetic nanoparticles of Fe3O4 and 5-bromotetrandrine on reversal of multidrug resistance in K562/A02 leukemic cells

This study aims to evaluate the multidrug resistance (MDR) reversal activity by magnetic nanoparticles of Fe3O4 (MNPs-Fe3O4) and 5-bromotetrandrine (BrTet) MDR cell line K562/A02 solitarily or symphysially. The proliferation of K562 and K562/A02 cells and the cytotoxicity on peripheral blood mononuclear cells (PMBCs) were evaluated by MTT assay. Cellular accumulation of daunorubicin (DNR) was analyzed by flow cytometry. Real-time polymerase chain reaction and Western blotting analyses were performed to examine the mRNA and protein levels of mdr1, respectively. The results showed that the combination of MNPs-Fe3O4 and BrTet with effective concentrations significantly increased cytotoxicity against MDR cell line K562/A02. Both BrTet and MNPs-Fe3O4 increased the intracellular DNR accumulation in the K562/A02 cell line, and downregulated the level of mdr1 gene and expression of P-glycoprotein. Furthermore, the combination did not have significant cytotoxicity in PMBCs. We propose that MNPs-Fe3O4 conjugated with DNR and BrTet probably have synergetic effects on MDR reversal.

Expression of multidrug resistance proteins in prostate cancer is related with cell sensitivity to chemotherapeutic drugs

BACKGROUND

Multidrug resistance (MDR) proteins have been associated with the lack of chemotherapy response. Expression of these proteins has been described in the prostate, but there is no information about their role in the chemotherapy response of prostate cancer (PC). We studied the gene and protein expression of MDR proteins in primary cell cultures from PC tumors and PC cell lines, their relationship with chemotherapy and their effects on cell survival.

METHODS

Primary cell cultures from PC were obtained from samples provided by our Institutional Hospital. Cell lines LNCaP, PC3, and DU145 were also examined. Cells were treated during 72 hr with several chemotherapeutic drugs. Protein and mRNA expressions of P-glycoprotein (P-Gp), MRP1 and LRP, before and after drug treatment, were evaluated by RT-PCR and Western blot analyses. The effect on cell survival was evaluated by proliferation assays (MTT), and cell cycle and apoptosis by flow cytometry.

RESULTS

Primary PC cultures exhibited higher MDR protein expression and lower drug sensitivity than cell lines, in which P-Gp was not detected. Docetaxel and mitoxantrone displayed the highest apoptotic effect. Exposure to chemotherapeutic drugs increased apoptosis, cell cycle arrest, and MDR expression. Long-term treatment with doxorubicin diminished apoptosis elicited by all drugs examined in this study, suggesting a cross-resistance phenomenon.

CONCLUSIONS

Low chemotherapy response observed in PC primary cultures could be explained, in part, by the high levels of MDR proteins (intrinsic MDR phenotype), and also, by their over-expression induced after long-term exposure to drugs (acquired MDR phenotype), which increase treatment resistance. Prostate 69: 1448-1459, 2009. (c) 2009 Wiley-Liss, Inc.

P-glycoprotein activity predicts outcome in childhood acute lymphoblastic leukemia

Treatment of children with acute lymphoblastic leukemia (ALL) is based on P-glycoprotein (P-gp)-dependent cytostatics. We assessed the P-gp function in blast cells as a possible prognostic factor and its influence on the overall survival. P-gp function was measured using the verapamil-sensitive Rhodamine efflux. Cell samples from 7 of 45 (16%) patients revealed rhodamine-efflux positive blasts. There were no relations between the presence of P-gp, clinical characteristics (age, sex, hepatomegaly, and splenomegaly) and initial laboratory parameters (immunophenotype, white blood cells count, and serum lactate dehydrogenase) in ALL. P-gp activity plays a negative role, both for a remission achieved on day 33 and for susceptibility to steroid therapy. Children bearing rhodamine-efflux positive blasts had a significantly shorter 5-year overall survival of 35%, as compared with 74% in those negative for P-gp function. Lack of any association with clinical characteristic and initial laboratory parameters suggests that presence of P-gp is an independent prognostic factor.

Multi-functional nanocarriers to overcome tumor drug resistance

The development of resistance to variety of chemotherapeutic agents is one of the major challenges in effective cancer treatment. Tumor cells are able to generate a multi-drug resistance (MDR) phenotype due to microenvironmental selection pressures. This review addresses the use of nanotechnology-based delivery systems to overcome MDR in solid tumors. Our own work along with evidence from the literature illustrates the development of various types of engineered nanocarriers specifically designed to enhance tumor-targeted delivery through passive and active targeting strategies. Additionally, multi-functional nanocarriers are developed to enhance drug delivery and overcome MDR by either simultaneous or sequential delivery of resistance modulators (e.g., with P-glycoprotein substrates), agents that regulate intracellular pH, agents that lower the apoptotic threshold (e.g., with ceramide), or in combination with energy delivery (e.g., sound, heat, and light) to enhance the effectiveness of anticancer agents in refractory tumors. In preclinical studies, the use of multi-functional nanocarriers has shown significant promise in enhancing cancer therapy, especially against MDR tumors.

Predictive value of multidrug resistance proteins and cellular drug resistance in childhood relapsed acute lymphoblastic leukemia

PURPOSE

Cellular resistance in childhood acute leukemias might be related to profile and function of multidrug resistance proteins and apoptosis regulating proteins. The aims of the study were: (1) analysis of expression of MRP1, PGP1, LRP, BCL-2 and p53 proteins; (2) correlation with ex vivo drug resistance, and (3) analysis of their prognostic impact on clinical outcome in childhood acute lymphoblastic (ALL) and acute myeloid (AML) leukemia.

METHODS

Total number of 787 children diagnosed for initial ALL (n = 527), relapsed ALL (n = 104), initial AML (n = 133) and relapsed AML (n = 23) were included into the study. Mean follow-up period was 3.5 years. Drug resistance for up to 30 anticancer agents was performed by the MTT assay. Expression of all proteins was tested by flow cytometry.

RESULTS

Both initial AML and relapsed ALL samples showed higher drug resistance than initial ALL samples. No significant differences were found in drug resistance between initial and relapsed AML samples. The presence of multidrug resistance and apoptosis proteins had no impact on pDFS in iALL and iAML, however strong trend towards adverse prognostic impact of MRP1, PGP and LRP on pDFS in rALL was observed. The same trend was observed for each of analyzed co-expressions of tested multidrug resistance proteins.

CONCLUSIONS

The phenomenon of cellular drug resistance in childhood acute leukemias is multifactorial and plays an important role in response to therapy. Expression of MRP1, PGP and LRP proteins, as well as their co-expression play possible role in childhood relapsed ALL.

MDR1, MRP1 and LRP expression in patients with untreated acute leukaemia: Correlation with 99mTc-MIBI bone marrow scintigraphy

BACKGROUND

Chemotherapy failure linked to multidrug-resistance (MDR) plays an important role in many cancer types, including leukaemia. It is believed that overexpression of some of membrane or intracellular proteins confers the MDR phenotype to cancer cells. (99m)Tc-sestamibi (MIBI) is a transport substrate for the Pgp pump. We assessed the bone marrow uptake of (99m)Tc-MIBI and its correlation with messenger RNA (mRNA) levels of MDR1, multidrug-resistance associated protein-1 (MRP1) and lung resistance protein (LRP) in acute leukaemia.

METHODS

A total of 26 patients (age range 17-72 years; mean age 51.88+/-2.52 years) with newly diagnosed acute leukaemia were included in the study. The expression of MDR1, MRP1 and LRP on mRNA levels were assessed by quantitative RT-PCR in the blast cells. The MIBI uptake in the bone marrow was evaluated using a quantitative scoring system with determination of the tumour-to-background ratios for the bone marrow areas. The correlation between the quantitative RT-PCR results and MIBI uptake was analysed by using Spearman's rank correlation coefficients with two-tailed test of significance.

RESULTS

There was an inverse relationship between (99m)Tc-MIBI uptake of bone marrow and both mRNA levels of MDR1 and MRP1 (P=0.000, r= -0.733 and P=0.001, r= -0.610, respectively). No correlation was found between MIBI uptake and mRNA levels of LRP.

CONCLUSION

Increased expression of MDR1 and MRP1 correlates with a low accumulation of (99m)Tc-MIBI in bone marrow areas in patients with acute leukaemia. (99m)Tc-MIBI bone marrow scintigraphy can identify the MDR1 and MRP1 phenotype, but not LRP, in patients with acute leukaemia.

Overcoming drug-resistant cancer by a newly developed copper chelate through host-protective cytokine-mediated apoptosis

PURPOSE

Previously, we have synthesized and characterized a novel Cu(II) complex, copper N-(2-hydroxy acetophenone) glycinate (CuNG). Herein, we have determined the efficacy of CuNG in overcoming multidrug-resistant cancer using drug-resistant murine and human cancer cell lines.

EXPERIMENTAL DESIGN

Action of CuNG following single i.m. administration (5 mg/kg body weight) was tested in vivo on doxorubicin-resistant Ehrlich ascites carcinoma (EAC/Dox)-bearing mice and doxorubicin-resistant sarcoma 180-bearing mice. Tumor size, ascitic load, and survival rates were monitored at regular intervals. Apoptosis of cancer cells was determined by cell cycle analysis, confocal microscopy, Annexin V binding, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay ex vivo. IFN-gamma and tumor necrosis factor-alpha were assayed in the culture supernatants of in vivo and in vitro CuNG-treated splenic mononuclear cells from EAC/Dox-bearing mice and their apoptogenic effect was determined. Source of IFN-gamma and changes in number of T regulatory marker-bearing cells in the tumor site following CuNG treatment were investigated by flow cytometry. Supernatants of in vitro CuNG-treated cultures of peripheral blood mononuclear cells from different drug-insensitive cancer patients were tested for presence of the apoptogenic cytokine IFN-gamma and its involvement in induction of apoptosis of doxorubicin-resistant CEM/ADR5000 cells.

RESULTS

CuNG treatment could resolve drug-resistant cancers through induction of apoptogenic cytokines, such as IFN-gamma and/or tumor necrosis factor-alpha, from splenic mononuclear cells or patient peripheral blood mononuclear cells and reduce the number of T regulatory marker-bearing cells while increase infiltration of IFN-gamma-producing T cells in the ascetic tumor site.

CONCLUSION

Our results show the potential usefulness of CuNG in immunotherapy of drug-resistant cancers irrespective of multidrug resistance phenotype.

Expression of P-glycoprotein, glutathione S-transferase-π, topoisomerase Ⅱ and lung resistance protein in cardiac carcinoma and their clinical significances

AIM: To investigate the expression of multidrug resistant proteins and their clinical significances in cardiac carcinoma tissues.

METHODS: The expression of P-glycoprotein (P-gp), glutathione S-transferase-p (GST-π), topoisomerase Ⅱ (Topo-Ⅱ) and lung resistance protein (LRP) in 69 patients with cardiac carcinoma were determined by SP immunohistochemistry,and the results were studied in correlation with clinicopathological data.

RESULTS: The positive rates of P-gp, GST-π, Topo-Ⅱ and LRP expression in cardiac carcinoma (49.2%, 75.4%, 68.1% and 58%, respectively) were all higher than those in the normal tissues (0, 30%, 20% and 0, respectively, all P < 0.01). The expression of P-gp was correlated with clinical staging (Ⅰ, Ⅱ vs Ⅲ, Ⅳ: 28.6% vs 58.3%, P < 0.05) and lymphatic metastasis (metastasis vs non-metastasis: 67.5% vs 24.1%, P < 0.01). A significant correlation was found between GST-π and differentiated degree (40%, 75.8% and 88.5% for high, moderate, and low differentiation, respectively, P < 0.05), clinical staging (Ⅰ, Ⅱ vs Ⅲ, Ⅳ: 57.1% vs 83.2%, P < 0.05) and lymphatic metastasis (metastasis vs non-metastasis: 87.5% vs 58.6%, P< 0.05). The level of Topo-Ⅱexpression was associated with differentiated degree (33.3%, 69.7%, and 80.7%, for high, moderate, and low differentiation, respectively, P < 0.01), but not with the clinical staging (P > 0.05) and lymphatic metastasis (P > 0.05). LRP expression was in correlation with the clinical staging (Ⅰ, Ⅱ vs Ⅲ, Ⅳ: 38% vs 66.6%, P < 0.05), and lymphatic metastasis (metastasis vs non-metastasis: 70.0% vs 41.4%, P < 0.05).

CONCLUSION: Primary multidrug resistance coexists in cardiac carcinoma. Combined determination of P-gp, GST-π, Topo-Ⅱand LRP is useful for predicting the chemosensitivities and optimizing the chemotherapy strategies.

Prognostic significance of multidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression in acute leukemia

The prognostic significance of multidrug resistance (MDR) gene expression is controversial. We investigated whether multidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression are associated with outcomes in acute leukemia patients. At diagnosis we examined MDR1, MRP and LRP mRNA expression in bone marrow samples from 71 acute leukemia patients (39 myeloid, 32 lymphoblastic) using nested RT-PCR. The expression of each of these genes was then expressed as a ratio in relation to beta-actin gene expression, and the three genes were categorized as being either 0, 1+, 2+ or 3+. MDR1, MRP and LRP mRNA expression was detected in 23.9%, 83.1% and 45.1 %, respectively. LRP mRNA expression was significantly associated with resistance to induction chemotherapy in acute leukemia patients, and in the AML proportion (p=0.02 and p=0.03, respectively). MRP and high MDR1 mRNA expression was associated with poorer 2-yr survival (p=0.049 and p=0.04, respectively). Patients expressing both MRP and LRP mRNA had poorer outcomes and had worse 2-yr survival. The present data suggest that MDR expression affects complete remission and survival rates in acute leukemia patients. Thus, determination of MDR gene expression at diagnosis appears likely to provide useful prognostic information for acute leukemia patients.

Prognostic significance of multidrug resistance-related proteins in childhood acute lymphoblastic leukaemia

An important problem in the treatment of children with acute lymphoblastic leukaemia (ALL) is pre-existent or acquired resistance to structurally and functionally unrelated chemotherapeutic compounds. Various cellular mechanisms can give rise to multidrug resistance (MDR). Best studied is the transmembrane protein-mediated efflux of cytotoxic compounds that leads to decreased cellular drug accumulation and toxicity. Several MDR-related efflux pumps have been characterised, including P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), breast cancer resistance protein (BCRP) and lung resistance protein (LRP). P-gp expression and/or activity has been associated with unfavourable outcome in paediatric ALL patients, whereas MRP1 and BCRP do not seem to play a major role. LRP might contribute to drug resistance in B-lineage ALL, but larger studies are needed to confirm these results. The present review summarises the current knowledge concerning multidrug resistance-related proteins and focuses on the clinical relevance and prognostic value of these efflux pumps in childhood ALL.