title: Ecto-5'-nucleotidase (CD73) in multidrug-resistant cell lines generated by doxorubicin.
abstract: Cytochemical screening for a panel of enzymes revealed increased 5' nucleotidase (5'NT) expression in 3 of 3 P-glycoprotein 170 (Pgp170)-positive multidrug-resistant (MDR) variants of the murine EL4 T-lymphoma cell line (EL4/ADM, ER2 and ER13). Electron microscopic localization established the presence of the membrane-bound ecto-form of the enzyme. Nine other murine, human and Chinese hamster cell lines and their MDR variants were tested for ecto-5'NT. Of these, 4 MDR variants (human cell lines MCF7A6, MCF7A2, HeLaJ2C and the murine cell line L1210A) showed increased expression of ecto-5'NT, when compared with their parental cell lines. The findings with cells of human origin were confirmed by immunofluorescent localization with a specific monoclonal antibody (MAb) (27.2) against the human ecto-5'NT. All MDR cell lines with elevated ecto-5'NT expression were generated by doxorubicin treatment. These cells were more sensitive than their parental cell lines to AMP at concentrations of 1.5-3.0 mM, confirming that the expressed ecto-5'NT was biologically active. The parental and MDR cells did not differ, in general, in their sensitivity to adenosine. An inhibitor of ecto-5'NT, alpha,beta-methyleneadenosine 5'-diphosphate, completely reversed the resistance of the EL4/ADM cell line to doxorubicin. The possibility exists of a functional relationship between the ecto-5'NT molecule and the members of the ATP-binding cassette transporter superfamily, important components of MDR, in some cell types.
authors.affiliation: Grace Cancer Drug Center, Roswell Park Cancer Institute, Buffalo, NY 14263.
authors.forename: P
authors.initials: P
authors.lastname: Ujházy
authors.forename: M
authors.initials: M
authors.lastname: Klobusická
authors.forename: O
authors.initials: O
authors.lastname: Babusíková
authors.forename: P
authors.initials: P
authors.lastname: Strausbauch
authors.forename: E
authors.initials: E
authors.lastname: Mihich
authors.forename: M J
authors.initials: MJ
authors.lastname: Ehrke
mesh_terms: D015720:5'-Nucleotidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000241:Adenosine / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D006224:Cricetinae; D003412:Cricetulus; D004317:Doxorubicin / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D008854:Microscopy, Electron; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000249:Adenosine Monophosphate; D004317:Doxorubicin; D015720:5'-Nucleotidase; D000241:Adenosine