title: A sensitive method for immunocytochemical detection of P-glycoprotein in multidrug-resistant human ovarian carcinoma cell lines.
abstract: P-glycoprotein, a molecular weight 170 kilodalton membrane component can be accurately detected in a series of human ovarian carcinoma cells with increasing degrees of multidrug resistance by using a modified immunoperoxidase "sandwich" method. Drug-resistant derivatives were selected from a drug-sensitive parent ovarian carcinoma cell line, SKOV3, by continuous exposure to increasing concentrations of the cytotoxic drug vincristine. These cells had corresponding overexpression of P-glycoprotein demonstrable at both protein and mRNA levels. Monoclonal antibodies against P-glycoprotein localized staining for P-glycoprotein to the plasma membrane and the Golgi region in individual drug-resistant cells, in proportion to their P-glycoprotein expression. P-glycoprotein was not demonstrable in drug-sensitive SKOV3 cells by either immunoblotting or immunocytochemical staining methods. The immunocytochemical staining method allowed detection of P-glycoprotein in the least drug-resistant cell line with as low as 8-fold relative resistance to vincristine. This method is as sensitive as Northern blot, and more sensitive than standard Western blot in detection of P-glycoprotein. We conclude that this highly sensitive immunocytochemical staining method for P-glycoprotein can be suitable for determination of P-glycoprotein expression in biopsy samples of tumors, and it can be a powerful diagnostic and prognostic tool in the study of the natural history of drug resistance. This may have important applications in the clinical management of cancer chemotherapy.
authors.affiliation: Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: H S
authors.initials: HS
authors.lastname: Chan
authors.forename: G
authors.initials: G
authors.lastname: Bradley
authors.forename: P
authors.initials: P
authors.lastname: Thorner
authors.forename: G
authors.initials: G
authors.lastname: Haddad
authors.forename: B L
authors.initials: BL
authors.lastname: Gallie
authors.forename: V
authors.initials: V
authors.lastname: Ling
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D015153:Blotting, Western; D002277:Carcinoma / Q000032:analysis*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000032:analysis*; D010051:Ovarian Neoplasms / Q000032:analysis*; D011237:Predictive Value of Tests; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D008562:Membrane Glycoproteins