Altered MDR1 expression and/or function contribute to the pathogenesis of inflammatory bowel disease (IBD). DNA methylation was shown as an important mechanism in gene silencing. We investigated DNA methylation of the MDR1 gene in ulcerative colitis (UC) and its relation to MDR1 C3435T genotypes. Eighty-three UC patients were enrolled. Methylation of MDR1 promoter was determined by methylation ...

No control cell line was available for previous RNA interference studies on reversal of multidrug resistance (MDR) in colon cancer cells. Here, human COLO 320DM, with HT-29 as the control, colon cancer cell lines were used to investigate the reversal of MDR1/P-gp-dependent MDR by siRNA (#4123 and #4029 MDR1 siRNAs) targeting to MDR1 mRNA. Both siRNAs inhibited expression of MDR1 and P-gp in COL...

INTRODUCTION: Studies using MDCKII and LLC-PK1 cells transfected with MDR1 cDNA indicate that ciprofloxacin is not a substrate of P-glycoprotein. However, our data has shown that transport studies done using different P-gp overexpressing cell lines (MDCKI-MDR1, MDCKII-MDR1 and L-MDR1), could lead to contradictory conclusion on whether a compound is a substrate of P-gp. The aim of our study was ...

Constitutive overexpression of the Mdr1 efflux pump is an important mechanism of acquired drug resistance in the yeast Candida albicans. The zinc cluster transcription factor Mrr1 is a central regulator of MDR1 expression, but other transcription factors have also been implicated in MDR1 regulation. To better understand how MDR1-mediated drug resistance is achieved in this fungal pathogen, we s...

background: for the first time we tested an association between the human multidrug resistance gene 1 (mdr1) polymorphisms (snps) and idiopathic pulmonary fibrosis (ipf). several mdr1 polymorphisms are associated with pathologies in which they modify the drug susceptibility and pharmacokinetics. materials and methods: we genotyped three mdr1 polymorphisms of 48 ipf patients and 100 control subj...

PURPOSE Activation of the MDR1 upstream promoter (USP) has been described previously in four lymphoblastic leukemia patients, where it is the major MDR1 promoter associated with P-glycoprotein overexpression. We asked whether MDR1 USP-derived transcripts were also present in breast carcinoma and assessed their potential as a biomarker. EXPERIMENTAL DESIGN We developed a sensitive method for d...

BACKGROUND P-glycoprotein (gp170; encoded by the MDR1 gene [also known as PGY1]) is a membrane protein capable of exporting a variety of anticancer drugs from cells. MDR1/gp170 expression has been studied in breast cancer, but the prevalence of this expression and its role in breast tumor drug resistance are unclear. PURPOSE We conducted a critical review and meta-analysis of studies examinin...

We investigated the mechanisms of MDR1 gene activation by CCAAT/enhancer binding protein beta (C/EBPbeta, or nuclear factor for interleukin 6) in human cancer cells. Transfection of the breast cancer cell line MCF-7 and its doxorubicin-selected variant MCF-7/ADR by either C/EBPbeta or C/EBPbeta-LIP (a dominant-negative form of C/EBPbeta) confirmed their roles in the activation or repression of ...

background: chemotherapy plays a very important role in the treatment of leukemia but the resistance properties of the lymphoblasts limit the effect of chemotherapy. one of the main mechanisms of resistance to chemotherapy is the increased expression of mdr1 gene. the aim of this study was to explore the effect of resveratrol on the expression of mdr1 gene in leukemic lymphoblast of new cases o...

Colon cancer is one of the most common cancers in the world. Overexpression of MDR1 mRNA and P-gp is associated with the classic multidrug resistance of colon cancer cells. In our previous study, we reported on the transient specific reversal of MDR1/P-gp-dependent multi-drug resistance by RNA interference (RNAi) in colon cancer cells. In this study, RNAi targeting the MDR1 gene stably reversed...