P-glycoprotein (P-gp), a membrane transporter encoded by MDR1 gene, influences pharmacokinetics of anti-cancer drugs and contributes to multi-drug resistance phenotype in adult acute lymphoblastic leukemia (ALL). In this study, we explored prognostic and functional role of single nucleotide polymorphism C3435T in MDR1 gene in 44 adult Caucasian patients with ALL. We found that the outcome of ch...

The extent of multidrug-resistance of human KB carcinoma cell lines has been shown to be proportional to the level of expression of the MDR1 gene. Using an in situ hybridization analysis with 35S-labeled RNA probes, we have found that there is some heterogeneity in expression of the MDR1 gene from cell to cell, but that the average level of expression is proportional to the resistance of the ce...

The expression of MDR1 gene was investigated in human solid tumors with respect to adriamycin resistance. Forty fresh human surgical specimens were analyzed by RNA dot blot assay for their expression of the human MDR1 gene and by immunohistological staining using a monoclonal antibody against P-glycoprotein (MDR1 gene product). The MDR1 mRNA level was increased in 11 cases of 40 cancer patients...

It has been suggested that expression of the P-glycoprotein transmembrane efflux pump (PGP), encoded by the multi-drug resistance (MDR1) gene, may play a role in the protection of epithelial tissues from a variety of local and systemic toxins. We report that in approximately 50% (6/11) of the population, MDR1 messenger RNA levels in the normal urinary epithelium are comparable to those found in...

Activation of the MDR1 (ABCB1) gene is a common event conferring multidrug resistance (MDR) in human cancers. We investigated MDR1 activation in MDR variants of a human sarcoma line, some of which express a mutant MDR1, which facilitated the study of allelic gene expression. Structural alterations of MDR1, gene copy numbers, and allelic expression were analyzed by cytogenetic karyotyping, oligo...

Resistance to multiple, unrelated cancer chemotherapeutic drugs can be mediated by P-glycoprotein, the MDR1 gene product. Numerous substances, including chemotherapeutic drugs, heavy metals, growth factors, activated oncogenes, or changes in temperature increase MDR1 gene expression. Because several of these factors regulate cellular function through the activation of phospholipase C (PLC), we ...

The bile canalicular membrane contains several ATP-dependent transporters that are involved in biliary secretion. Canalicular transporters are synthesized in ER, modified in Golgi and transported to the apical plasma membrane. However, the route and regulation of intracellular trafficking of ATP-dependent transporters have not been elucidated. In the present study, we generated a translational ...

BACKGROUND Multidrug resistance-related protein 1 (MRP1/ABCC1) and multidrug resistance protein 1 (MDR1/P-glycoprotein/ABCB1) are both membrane-bound drug transporters. In contrast to MDR1, MRP1 also transports glutathione (GSH) and drugs conjugated to GSH. Due to its extraordinary transport properties, MRP1/ABCC1 contributes to several physiological functions and pathophysiological incidents. ...

P-glycoprotein (Pgp) [the product of the MDR1 (ABCB1) gene] at the blood-brain barrier (BBB) limits central nervous system (CNS) entry of many prescribed drugs, contributing to the poor success rate of CNS drug candidates. Modulating Pgp expression could improve drug delivery into the brain; however, assays to predict regulation of human BBB Pgp are lacking. We developed a transgenic mouse mode...

Expression of the human MDR1 gene has been shown to confer the multidrug resistance (MDR) phenotype to sensitive cells. To investigate the possible contribution of the MDR phenotype to chemoresistance in ovarian carcinoma, we have analyzed MDR1 gene expression in fresh carcinoma specimens from 50 patients. Fifteen received chemotherapy before surgery and were judged as poor responders. Thirty-f...