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The epithelial Na + channel (ENaC) that mediates regulated Na + reabsorption by epithelial cells in the kidney and lungs can be activated by endogenous proteases such as channel activating protease 1 and exogenous proteases such as trypsin and neutrophil elastase (NE). The mechanism by which exogenous proteases activate the channel is unknown. To test the(More)
PURPOSE Cancers exposed to chemotherapy develop multidrug resistance, a major cause for chemotherapy failure. One mechanism of multidrug resistance development is due to overexpression of P-glycoprotein (Pgp) in these cancer cells. Thus, a prechemotherapy evaluation of Pgp in cancer cells aids in the design of alternative regimens that can circumvent such(More)
The interactions between the human P-glycoprotein (Pgp) and two different types of immunosuppressant drugs known to modulate multidrug resistance in tumor cells have been directly investigated using our newly developed drug-stimulated ATPase assay for Pgp function. The macrolides FK506 and FK520 stimulate the Pgp-ATPase activity with affinities in the 100(More)
The plasma membrane H(+)-ATPase of Neurospora crassa was treated with 5,5'-dithiobis(2-nitrobenzoate) to determine its cysteine content and with 2-nitro-5-thiosulfobenzoate to determine its cystine content. Six and seven mol of thiols/mol of H(+)-ATPase were detected in the 5,5'-dithiobis(2-nitrobenzoate) and 2-nitro-5-thiosulfobenzoate reactions,(More)
To gather further insight into the interaction between P-glycoprotein (Pgp) and its substrates, 167 compounds were analyzed in multidrug resistant human colon carcinoma cells. These compounds were selected from the National Cancer Institute Drug Screen repository using computer-generated correlations with known Pgp substrates and antagonists. The compounds(More)
Bioflavonoids are of considerable interest to human health as these serve as antioxidant and anticancer agents. Although epidemiological and experimental studies suggest that luteolin, a natural bioflavonoid, exhibits chemopreventive properties, its effectiveness as an antiproliferative agent against multidrug resistant (MDR) cancers is unclear. Thus, we(More)
Multidrug-resistant (MDR) tumor cells reduce the toxicity of antineoplastic drugs by an energy-dependent active efflux mechanism mediated by the MDR1 gene product, the P-glycoprotein (Pgp). Pgp expressed in cultured Sf9 insect cells has been shown to exhibit a high capacity ATPase activity in the presence of a variety of drugs known to be transported by the(More)
RNF2, a member of polycomb group (PcG) proteins, is involved in chromatin remodeling. However, mechanisms that regulate RNF2 function are unknown. To identify such mechanisms, RNF2 was expressed in HEK-293 cells and analyzed by 2-D electrophoresis. RNF2 was resolved into at least seven protein spots, migrating toward the lower pI from its expected pI of(More)
Development of colorectal cancer (CRC) involves a series of genetic alterations with altered expression of proteins and cell signaling pathways. Here, we identified that galectin-4 (gal-4), a marker of differentiation, was down-regulated in CRC. The goal of this work was to determine the function of gal-4 in CRC. Toward this goal, the human colon biopsies(More)
  • U S Rao
  • 1995
A single amino acid substitution, Gly185-->Val, in the human P-glycoprotein (Pgp) was previously shown to cause an altered pattern of drug resistance in cell lines transfected with the MDR1 cDNA carrying this mutation. To further define the function of amino acid 185 in the Pgp, the wild-type and the mutant Val185 Pgps were expressed in Sf9 insect cells,(More)