Transduction of murine stem cells with a multidrug-resistance 1 gene (MDR1) retrovirus results in dramatic ex vivo and in vivo expansion of repopulating cells accompanied by a myeloproliferative disorder. Given the use of MDR1-containing vectors in human trials, investigations have been extended to nonhuman primates. Peripheral blood stem cells from 2 rhesus monkeys were collected, CD34-enriche...

The impact of BCR-ABL mRNA type (b3a2 vs. b2a2) on chronic myeloid leukemia (CML) phenotype is still a subject of controversies. We searched for a correlation between the BCR-ABL transcripts type and CML patients' characteristics, including MDR1 gene expression. Ninety-eight untreated chronic phase CML patients were studied. The type of BCR-ABL fusion transcripts and MDR1 gene expression were d...

To evaluate the clinical significance of drug resistance mechanisms in breast cancer, we examined the expression of MDR1 and MRP in primary breast carcinoma and normal adjacent tissue using a highly quantitative and reproducible reverse transcription-PCR assay. Expression of both genes was observed in all specimens examined, both tumor (n = 74) and normal adjacent tissue (n = 55). The expressio...

PURPOSE Pregnane x receptor (PXR) - activated overexpression of the multidrug resistance 1 (MDR1) gene is an important way for tumor cells to acquire drug resistance. However, the detailed mechanism still remains unclear. In the present study, we aimed to investigate whether protein arginine methyl transferase 1(PRMT1) is involved in PXR - activated overexpression of MDR1 during acquired multid...

Simultaneous resistance of cancer cells to multiple cytotoxic drugs, multidrug resistance (MDR), is the major limitation to the successful chemotherapeutic treatment of disseminated neoplasms. The 'classical' MDR phenotype is conferred by MDR1/P-glycoprotein (MDR1/P-gp) that is expressed in almost 50% of human cancers. Recent developments in the use of small interfering RNAs for specific inhibi...

The multidrug-resistance gene, MDR1 is expressed in many normal tissues, but little is known about its expression in normal hematopoietic cells. Using the monoclonal antibody C219 and flow cytometric analysis, P-glycoprotein (P-gp) was found to be expressed in all peripheral blood (PB) subpopulations (CD4, CD8, CD14, CD19, CD56) except granulocytes. To specifically determine MDR1 gene expressio...

We have previously demonstrated that within 24 h of exposure of the CEM/A7R cell line to epirubicin (EPI), MDR1 gene expression is induced. The aim of the current study was to investigate the role of cyclosporin A (CyA) and PSC 833, two biochemical modulators of the classical multidrug-resistant phenotype, in this model. CEM/A7R cells were exposed to EPI in the presence or absence of various co...

One of the limitations in the treatment of cancer patients with chemotherapy is the development of multidrug resistance (MDR). A well-known mechanism responsible for drug resistance is over-expression of ABC-transporter genes such as MDR1. This gene encodes p-glycoprotein (P-gp), a transmembrane glycoprotein that transports many hydrophobic substrates and anti-cancer drugs out of the cell. MDR1...

The multidrug resistance 1 (MDR1) gene encodes a M(r) 170,000 membrane glycoprotein termed P-glycoprotein, which catalyzes the energy-dependent efflux of multiple anticancer agents. We investigated the activation of the MDR1 gene promoter by UV light irradiation in human cancer KB cells after both transient and stable transfection assays of the MDR1 promoter fused to the chloramphenicol acetylt...