Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.3.44 (P-glycoprotein)
 13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report a patient with aplastic anemia (AA)-paroxysmal nocturnal hemoglobinuria (PNH) syndrome who developed acute myelogenous leukemia (AML). Flow cytometric analysis showed that the leukemic cells in the bone marrow lacked CD59 antigen on their surface and were positive for P-glycoprotein. Heteroduplex and single-strand conformation polymorphism analysis followed by sequencing of the leukemic cells in the bone marrow disclosed 1 frameshift-type mutation in exon 2 of the phosphatidylinositol glycan-class A (PIG-A) gene, which deductively produces truncated PIG-A protein. These findings provide direct evidence that the leukemic cells evolved from the affected PNH clone. Cytogenetic analysis in the bone marrow in each stage of AA-PNH, AML, and at relapse of AML showed normal, -7, and -7 plus -20, respectively, showing evidence of a clonal evolution. Because complete remission of AML was not achieved by intensive chemotherapies, allogeneic peripheral blood stem cell transplantation (PBSCT) from the patient's HLA-matched sister was performed successfully with recovery of CD59 antigen on bone marrow hematopoietic cells; however, leukemia relapsed 4 months after PBSCT. Leukemia derived from PNH may be resistant to intensive chemotherapy, and a highly myeloablative regimen may be required for stem cell transplantation to eradicate the PNH-derived leukemia clone.
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PMID:Acute myelogenous leukemia with PIG-A gene mutation evolved from aplastic anemia-paroxysmal nocturnal hemoglobinuria syndrome. 1137 33

Anaplastic thyroid carcinoma is a rapidly growing, aggressive neoplasm affecting the elderly which does not respond to most of the therapies. We established cultured cell lines from four untreated tumors. The cultures grew in a monolayer of spindle-shaped cells in three cell lines and of small polygonal cells in one line, having relatively long doubling times and chromosomal abnormalities. The xenotransplantation of the lines in athymic nude mice produced tumors with a histology similar to the original tumors. The immunocytochemical staining showed the expression of PCNA, HLA-class 1, cytokeratin, vimentin and FAS (fatty acid synthase) but not CEA, desmin or P-glycoprotein. The lines secreted TPA, IL-6, IL-8 and few or no thyroid-related hormones in the culture supernatant. One cell line produced G-CSF. The chemosensitivity assay revealed intrinsic drug resistance to nine out of 11 antineoplastic agents. The reverse transcriptase-polymerase chain reaction (RT-PCR) detected MRP (multidrug resistance-associated protein) mRNA but not mdr (multidrug resistance protein)-1 and mdr-3 mRNAs. This finding indicates that the multidrug resistance of these lines is mediated by a P-glycoprotein-unrelated mechanism. The RT-PCR also presented FAS mRNA in all the lines, and IL-6 and IL-8 mRNAs in some of the lines.
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PMID:Biological characteristics and chemosensitivity profile of four human anaplastic thyroid carcinoma cell lines. 1168 81

Based on our previous demonstration that quinine could be used clinically to reverse P-glycoprotein-mediated resistance, we designed a multicenter, randomized trial aiming to determine whether quinine would improve the survival of adult patients (15-60 years old) with de novo acute myelogenous leukemia (AML). These patients randomly received (n = 213) or did not receive (n = 212) a 30 mg/kg/day continuous intravenous infusion of quinine in combination with induction chemotherapy combining idarubicine and cytarabine and, depending on bone marrow examination at day 20, an additional course of cytarabine and mitoxantrone. The mean steady-state quinine concentration was 7.8 mg/L and the mean multidrug resistance reversing activity of serum was 1.96. Complete remission (CR) was obtained in 344 patients (80.9%) without significant influence of quinine. Of the patients in complete remission, 82 were assigned to receive HLA-matched bone marrow transplants, whereas 262 were assigned to 2 courses of intensive consolidation chemotherapy, with or without quinine, depending on initial randomization. The 4-year actuarial overall survival (OS) of the 425 eligible patients was 42.0% +/- 2.5%, without significant influence of quinine. Of 160 patients who could be studied, 54 demonstrated rhodamine 123 efflux. In these patients, quinine significantly improved the CR rate from 12 of 25 (48.0%) to 24 of 29 (82.8%) (P =.01). However, there was no significant difference in OS. Neither mdr1 gene nor P-glycoprotein expression influenced the outcome. We conclude that quinine does not improve the survival of adult patients with de novo AML, even though it improves CR rate in a small subgroup of patients defined by rhodamine 123 efflux.
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PMID:Quinine as a multidrug resistance inhibitor: a phase 3 multicentric randomized study in adult de novo acute myelogenous leukemia. 1266 40

An abnormal HLA expression has been detected in some tumors including rhabdomyosarcoma (RMS). Classical cytotoxic treatment of these tumors, the most common childhood soft tissue malignancy, may induce multidrug resistance (MDR) associated with the expression of a 170-kDa membrane-associated glycoprotein (P-glycoprotein). In order to analyse the connection between modulation of HLA expression and the development of the MDR phenotype mediated by P-glycoprotein in RMS, we used three resistant RMS cell lines; two of these resistant cell lines (TE.32.7.DAC and RD-DAC) were established by in vitro exposure to actinomycin D, a drug of choice in the treatment of RMS; the resistant RMS- GR cell line was established from an embryonal RMS tumor after polychemotherapy. Our results showed that all the resistant cell lines showed a significant increase in the expression of HLA class I surface antigens in comparison to drug-sensitive cells. Blockade of P-glycoprotein with verapamil led to a decrease in HLA class I expression in RMS resistant cell lines. However, no modulation of HLA class II expression was observed in any of the three analyzed cell lines. These findings support the hypothesis that the development of resistance mediated by mdr 1/P-glycoprotein, directly influences the expression of HLA class I in RMS cells, inducing to upregulation. This effect may be relevant to the application in RMS of immunotherapy against tumor-associated antigens presented by HLA class I molecules.
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PMID:Modulation of HLA class I expression in multidrug-resistant human rhabdomyosarcoma cells. 1274 Jun 41

Persistent rejection in the face of treatment and multiple episodes of rejection are associated with the development of chronic rejection and graft loss in solid organ transplantation. The factors that create an environment for rejection that persists in the face of treatment are as yet not understood. The objective of this study was to evaluate the risk factors, including human multidrug resistance gene (MDR1), cytochrome P4503A5 (CYP3A5) and cytokine gene polymorphisms, associated with acute persistent rejection (APR) in lung transplant patients. One hundred and twenty-five adult lung transplant patients were studied. MDR1 G2677T, C3435T and CYP3A5 polymorphisms were assessed by direct sequencing of the polymorphic region in patient DNA. Cytokine genotyping for five cytokines was performed using the polymerase chain reaction-sequence specific primers (PCR-SSP) technique. Multivariate regression analysis was used to identify the predictors of acute persistent rejection. The dependent variable was the presence or absence of acute persistent rejection based on lung biopsies during the first postoperative year. The independent variables were MDR1 G2677T and C3435T, CYP4503A5 and cytokine polymorphisms, survival status, age, gender, survival days and HLA mismatches. The MDR1 C3435T polymorphism and age were independently associated with acute persistent rejection (p = 0.025, odds ratio = 0.29, 95% CI 0.1-0.86 and p = 0.016, odds ratio = 0.94, 95% CI 0.89-0.98, respectively). For the MDR1 C3435T polymorphism, 72% of patients with the C allele had acute persistent rejection in comparison to 52% for TT patients (p = 0.04). For age, a significant difference was found between the nonrejection group and the rejection group (mean+/-S.D. 52.1+/-11.2 vs. 44.4+/-12.3, p = 0.01). This is the first report of the association of a drug disposition genotype with drug-resistant acute rejection in organ transplant patients. The major predictor of acute persistent rejection in the first postoperative year for lung transplant patients was the MDR1 C3435T genotype. This association could be due to drug resistance, altered drug disposition or other immunologic effects associated with P-glycoprotein (P-gp) function. Future prospective treatment algorithms should be developed that will incorporate the knowledge of gene polymorphisms into treatment regimens to improve the outcome following lung transplantation.
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PMID:The impact of pharmacogenomic factors on acute persistent rejection in adult lung transplant patients. 1581 80

Relapse is a major obstacle in the cure of acute myeloid leukemia (AML). The Pediatric Oncology Group AML Study 9421 tested 2 different strategies to improve event-free survival (EFS) and overall survival (OS). Patients were randomized to receive standard-dose DAT (daunorubicin, cytarabine, and thioguanine) or high-dose DAT during induction. To interfere with P-glycoprotein (P-gp)-dependent drug efflux, the second randomization tested the benefit of cyclosporine (CsA) added to consolidation chemotherapy. Of the 282 children randomly assigned to receive standard DAT induction, 248 (87.9%) achieved remission compared to 253 (91%) of the 278 receiving high-dose DAT (P = ns). Children with HLA-identical sibling donors who achieved a complete remission received an allogeneic bone marrow transplant as consolidation. For the 83 patients receiving a matched related donor bone marrow transplantation (BMT), the 3-year disease-free survival (DFS) is 67%. Of the 418 children who achieved remission and went on to consolidation with and without CsA, the DFS was 40.6% and 33.9%, respectively (P = .24). Overexpression of P-gp was infrequent (14%) in this pediatric population. In this study, intensifying induction with high-dose DAT and the addition of CsA to consolidation chemotherapy did not prolong the durations of remission or improve overall survival for children with AML.
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PMID:Randomized use of cyclosporin A (CsA) to modulate P-glycoprotein in children with AML in remission: Pediatric Oncology Group Study 9421. 1675 81

Effectiveness of conventional cytotoxic treatment of rhabdomyosarcoma (RMS) may be limited by the development of multidrug resistance (MDR) mediated by mdr1 gene. This gene codes for P-glycoprotein (P-gp) which has been related to a immunoregulatory function. Modulation of HLA expression by P-gp has been described in different types of tumor cells including RMS. However, very little is known about biological implications of the P-gp expression in RMS patients treated with conventional chemotherapy. In order to study the problem, we used embryonal RMS tissue samples from treated patients. Our results indicated that positive RMS samples to mdr1 show higher HLA class I expression than those which were negative to mdr1 PCR, what indicates a significant correlation between the expression of both molecules. In addition, we developed two resistant RMS cell lines (A-204-1 and 2) using similar concentrations of actinomycin D as are plasma levels in clinical situation. Both resistant cell lines showed mdr1 expression and an increase of HLA class I expression which was dose-dependent. These results demonstrated that conventional chemotherapy of embryonal RMS is able to induce resistance which can modulate HLA class I expression and suggest that immunological studies of these tumors may be necessary to the design new specific therapeutic strategies.
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PMID:Induction of drug resistance in embryonal rhabdomyosarcoma treated with conventional chemotherapy is associated with HLA class I increase. 1665 92

Fludarabine phosphate (FLU), the 2-fluro derivative of Ara-A, 9-beta-D-arabino-furanosyl-2-fluoroadenine, has been shown to display both in vitro and in vivo antiproliferative activity toward a variety of murine tumors and human lymphoid malignancies. In the present study, we have determined the effect of FLU, alone and in combination with recombinant human fibroblast interferon (IFN-B), on in vitro growth, gene expression and the antigenic phenotype of human glioblastoma multiforme (GBM) cells displaying a multidrug sensitive and a multidrug resistant (MDR) phenotype. FLU exhibited a marked differential toxicity toward GBM-MDR cells versus the multidrug sensitive GBM parental cell line. Growth of GBM-MDR cells for seven days in 2.5 to 7.5 muM FLU resulted in a dose-dependent reduction or elimination of growth which persisted after removal of this agent. In contrast, recovery from FLU-induced growth suppression was observed in parental multidrug sensitive GBM cells. Acquisition of increased FLU sensitivity in GBM-MDR cells did not appear to result from selection for a subset of sensitive cells or an artifact associated with the DNA-transfection process. This conclusion is supported by the similar pattern of FLU resistance in GBM-18 clones isolated after transfection with a cloned hygromycin resistance gene and selection for resistance to hygromycin. The antiproliferative and toxic effect of FLU was increased in GBM-MDR cells by simultaneous growth in IFN-B and the toxic effect of FLU could be blocked in a dose-dependent manner by the simultaneous addition of deoxycytidine. In contrast, the toxicity of FLU toward GBM-MDR cells was not altered when cells were grown in the presence or absence of colchicine or by the administration of verapamil, which can reverse the MDR phenotype in GBM-MDR cells. The selective toxicity of FLU toward GBM-MDR versus GBM-18 cells was not associated with a consistent differential change in all of the GBM-18 MDR clones in the steady-state mRNA levels of a number of genes, including mdr-1, c-myc, c-fos, JunB, C-jun, proliferative cell nuclear antigen (PCNA), interferon stimulated gene-15 (ISG-15), fibronectin, tenascin, Class I HLA antigen, intercellular adhesion molecule I (ICAM-1), beta-actin or GAPDH. A common change observed in both parental GBM-18 cells and MDR GBM-18 clones exposed to FLU was an increase in the steady-state mRNA levels of deoxycytidine kinase (DCT). Analysis of the antigenic phenotype in GBM and GBM-MDR cells by fluorescence activated cell sorter (FACS) analysis using specific monoclonal antibodies (MoAbs) recognizing ICAM-1, Class I HLA antigen and a high molecular weight-melanoma associated antigen (HMW-MAA) indicated that FLU was generally more active as an immunomodulating agent in MDR versus non-MDR GBM cells. Although the mechanism underlying the differential effect of FLU toward GBM-MDR versus GBM cells is not presently known, the present findings indicate that the growth inhibitory and immunomodulatory effects of FLU are enhanced in cells expressing an MDR phenotype resulting from overexpression of a cell membrane localized 170,000 M(r) glycoprotein (P-glycoprotein).
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PMID:Fludarabine phosphate selectively inhibits growth and modifies the antigenic phenotype of human glioblastoma-multiforme cells expressing a multidrug resistance phenotype. 2158 36