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)

Results concerning a possible link between susceptibility to natural-cell-mediated immune cytolysis and the multi-drug resistance (MDR) phenotype are conflicting. We evaluated in human acute lymphocytic leukemia the relationship between acquired drug resistance and susceptibility to cytolysis mediated by endogenous, interferon-activated, and interleukin-2-activated natural cytotoxic cells. Eight human leukemia drug-resistant/sensitive cell line pairs were evaluated; drug-resistant sub-lines included those selected for primary resistance to adriamycin, etoposide, teniposide, vincristine, and vinblastine. A majority of P-glycoprotein-positive MDR sub-lines displayed slight but statistically significant resistance to endogenous and/or interferon-activated natural-killer(NK)-cell-mediated lysis, as compared with the drug-sensitive parental type. P-glycoprotein-negative sub-lines displayed variable NK susceptibility; within this group, the variants selected for primary etoposide resistance were more susceptible to NK cytolysis than parental cells. Results of cold-target-inhibition experiments suggest that altered NK susceptibility does not arise solely from modulation of NK target recognition and adherence structures. IL2-activated killer (LAK) cells lysed both drug-sensitive and drug-resistant lines. Two MDR lines selected for primary etoposide resistance displayed enhanced LAK susceptibility. In contrast, the 2 variants selected for resistance to adriamycin exhibited partial resistance to LAK-mediated killing, which could be overcome at high effector-to-target ratios. Our results support the development of interleukin-2/LAK immunotherapy for the treatment of leukemias with acquired drug resistance.
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PMID:The relationship between multi-drug resistance and resistance to natural-killer-cell and lymphokine-activated killer-cell lysis in human leukemic cell lines. 137 Apr 37

We have shown previously that (a) aging leads to an increase in the proportion of murine splenic T cells that express high activity of P-glycoprotein (PGP), the ATP-dependent plasma membrane pump that mediates multiple drug resistance, and (b) PGPhi CD4 memory cells from mice of any age do not proliferate or secrete IL-4 after activation with anti-CD3 and IL2. We now report that the age-associated increase in expression of MHC Class I molecules is limited to the subset of T cells that overexpress PGP and thus extrude the fluorochrome R123 (the "R123lo" subset). Although H-2 levels increase on T cells of old mice, the levels of TAP1, a component of the polypeptide pump responsible for assembly and internal transport of Class I MHC molecules, decline, unexpectedly, by about fourfold in T cells from old donors. Thus, aging leads to reciprocal changes in the level of T-cell expression of PGP and TAP1, two closely related members of the ABC superfamily of peptide transport proteins.
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PMID:Reciprocal expression of P-glycoprotein and TAP1 accompanied by higher expression of MHC class I antigens in T cells of old mice. 854 4

In the present study, we examined the effect of interleukin-2 (IL-2) gene transfer into multidrug resistance (MDR) cancer cells on the therapeutic efficacy of MRK16. Human MDR ovarian cancer cells, AD10, were transduced with a bicistronic IL-2 retrovirus, Ha-IL2-IRES-Neo. The G418-resistant population, IL2-AD10, secreted IL-2 into the culture supernatant and did not form a tumor mass in nude mice. The IL2-AD10 cells were more susceptible to the cytotoxicity of murine spleen cells than AD10 cells in vitro. For examination of the effect of IL-2 gene transfer on the antitumor activity of MRK16 against P-glycoprotein-positive tumors, IL2-AD10 cells were co-transplanted s.c. with AD10 cells into nude mice in a ratio of 1:3, and the mice were treated with MRK16 on days 2 and 7. MRK16 markedly inhibited the growth of AD10 cells mixed with IL2-AD10 cells under conditions (0.3-1 microgram/body) where it showed only marginal effects on the growth of AD10 tumors. These findings suggest that IL-2 gene transfer potentiates the antitumor activity of MRK16 against MDR tumors.
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PMID:Combination therapy with antibody and interleukin-2 gene transfer against multidrug-resistant cancer cells. 943 86

Inhibitors of P-glycoprotein (P-gp) (verapamil) or cytochrome P-450 (ketoconazole) may reduce IL2 production and T lymphocyte proliferation in vitro. We have examined the effects of chronic oral administration of these drugs and of the cytochrome P450 inductor, carbamazepine, on the hematological and immunological parameters of mice. We found no changes after giving the mice 0.12 mg verapamil, 0.85 mg ketoconazole, or 0.514 mg carbamazepine per mouse for 4 weeks (5 days/week). But giving the drugs for an additional 7 weeks at 0.6 mg (verapamil), 4.25 mg (ketoconazole) or 2.57 mg/mouse (carbamazepine), resulted in significant decreases in monocytes in the verapamil treated group (-51%) and in CD4+ cells in the carbamazepine group (-35%). Chronic oral administration of these drugs reduced the lymphocyte counts of mice by 10-18% and their NK counts by 10-16%. These changes could be due to changes in P-gp function in the transport of IL2, with decreases caused by verapamil and ketoconazole.
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PMID:Chronic administration of verapamil, ketoconazole and carbamazepine: impact on immunological parameters. 1199 17