Multidrug resistance to anticancer drugs, which is often associated with enhanced expression of the ATP‑binding cassette (ABC) transporter P‑glycoprotein (encoded by the ABCB1 gene) may limit the effects of cancer therapy.
Since P-glycoproteins control the extrusion of a broad range of toxins and xenobiotics and are responsible for drug resistance in many diseases including cancer and brain diseases such as epilepsy, we propose that the failure of NDGA in maintaining glutamate uptake upregulated in SOD1-G93A mice and its therapeutic inefficacy are due to acquired pharmacoresistance mediated by the increased expression of P-glycoprotein.
Unlike in previous reports the mdr1 promoter was no more active in two cancer cell lines with mutations in the p53 gene than in two other lines with wild-type p53, and its expression level could not be increased by either doxorubicin or taxol.
Summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for MDR1C3435T polymorphism and cancer were estimated using fixed- and random-effects models when appropriate.
We also found that the 3435TT genotype of MDR1 was associated with a lower risk of non-cardiac cancer (OR = 0.42; 95% CI = 0.23-0.79), middle-third cancer (OR = 0.36; 95% CI = 0.17-0.77), advanced cancer (OR = 0.31; 95% CI = 0.13-0.73), venous invasion (OR = 0.30; 95% CI = 0.10-0.91), and lymph node metastasis (OR = 0.28; 95% CI = 0.13-0.65).
Pharmacologically active in vivo doses of P-glycoprotein (Pgp) blockers, specifically verapamil, Cremophor EL and PSC833 cause toxicity in addition to that from the concomitantly used cancer chemotherapeutic drugs.
Younger age, history of pregnancy-related nausea, fewer hours slept the night prior to infusion, and variation in ABCB1 were associated with more severe acute nausea; advanced-stage cancer and receipt of highly emetogenic chemotherapy were associated with more severe delayed nausea (p values < 0.05).
Increased expression of the mdr-1 gene encoding the drug efflux pump P-glycoprotein is a well-established mediator of acquired drug resistance in vitro, and a similar role has been hypothesized in vivo in human malignancy.
Each of three 3435TT, C1236TT, 2677TT genotypes of ABCB1 and their combination was associated with about 50% higher anti-emetic response to 5-HT3 receptor antagonists in the acute phase of chemotherapy in patients with cancer receiving moderately or highly emetogenic chemotherapy.
Multidrug resistance (MDR) is a major obstacle in cancer treatment due to the ability of tumor cells to efflux chemotherapeutics via drug transporters (<i>e.g.</i> P-glycoprotein (Pgp; ABCB1)).
This safety-modified vector should be useful for introducing the MDR1 gene into bone marrow cells to protect normal cells from the toxic effects of cancer chemotherapy.
To clarify the role of MDR1 in this malignancy, we examined the relationship between MDR1 expression and patient outcome in subsets of 60 primary untreated neuroblastomas for which MYCN gene copy number and expression of the multidrug resistance-associated-protein (MRP) gene had been previously characterised.
Interest in chloride channels related to cancer first arose when the multidrug resistance protein (MDR/P-glycoprotein) was linked to volume-activated chloride channel activity in cancer cells from patients undergoing chemotherapy.
All three N276 compounds almost completely reversed the acquired resistance to vincristine (VCR), vinblastine (VBL), and doxorubicin (DXR) in MDR1-overexpressing human cancer cell lines (KB/VJ300 and T24/VCR).