title: The 95-kilodalton membrane glycoprotein overexpressed in novel multidrug-resistant breast cancer cells is NCA, the nonspecific cross-reacting antigen of carcinoembryonic antigen.
abstract: Human breast carcinoma MCF-7/AdrVp cells display a novel multidrug resistance phenotype that is characterized by the overexpression of a 95-kDa membrane glycoprotein (p95) and by marked reduction in intracellular anthracycline accumulation, without overexpression of P-glycoprotein or the multidrug resistance protein MRP. p95 is also highly expressed in multidrug-resistant NCI-H1688 cells derived from a human small cell lung carcinoma. Deglycoslyated p95 from NCI-H1688 cells was isolated by two-dimensional gel electrophoresis and then digested with trypsin. The tryptic peptides were analyzed by mass spectrometry and microsequencing. These analyses identified p95 to be identical to NCA-90, the nonspecific cross-reacting antigen related to the carcinoembryonic antigen (CEA). Further confirmation that p95 is indeed NCA-90 was obtained by Northern and Western blot studies using probes or antibodies specific for p95, NCA-90, or CEA family members. Western blot studies also revealed that CEA itself is overexpressed in MCF-7/AdrVp cells compared to parental MCF-7/W cells. The enforced expression of NCA-90 protein in HeLa cells stably transfected with NCA-90 cDNA did not result in increased resistance of the transfected cells to daunorubicin or a decrease in daunorubicin accumulation in the transfected cells compared to cells transfected only with the expression vector. However, a recent report by H. Kawaharata et al. (Int. J. Cancer, 72: 377-382, 1997) of diminished accumulation, retention, and cytotoxicity of doxorubicin in EJNIH3T3 cells in which enforced expression of CEA was accomplished leaves open the possibility that the overexpression of CEA, possibly in combination with that of NCA-90, could account at least in part for the drug resistant phenotype displayed by MCF-7/AdrVp cells.
authors.affiliation: Greenebaum Cancer Center of the University of Maryland and the Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. dross@umcc01.umcc.ab.umd.edu
authors.forename: D D
authors.initials: DD
authors.lastname: Ross
authors.forename: Y
authors.initials: Y
authors.lastname: Gao
authors.forename: W
authors.initials: W
authors.lastname: Yang
authors.forename: J
authors.initials: J
authors.lastname: Leszyk
authors.forename: J
authors.initials: J
authors.lastname: Shively
authors.forename: L A
authors.initials: LA
authors.lastname: Doyle
mesh_terms: D016475:3T3 Cells / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000951:Antigens, Neoplasm; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000737:chemistry* / Q000188:drug therapy / Q000378:metabolism*; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D015815:Cell Adhesion Molecules; D003429:Cross Reactions; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D015180:Electrophoresis, Gel, Two-Dimensional; D000939:Epitopes; D006367:HeLa Cells; D006801:Humans; D007525:Isoelectric Focusing; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D010641:Phenotype; D012967:Sodium Dodecyl Sulfate; D014407:Tumor Cells, Cultured
chemical_list: D000903:Antibiotics, Antineoplastic; D000951:Antigens, Neoplasm; D002272:Carcinoembryonic Antigen; D015815:Cell Adhesion Molecules; D000939:Epitopes; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D012967:Sodium Dodecyl Sulfate; D004317:Doxorubicin