A sensitive method for immunocytochemical detection of P-glycoprotein in multidrug-resistant human ovarian carcinoma cell lines.
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.
Chan
H S
HS
Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada.
Bradley
G
G
Thorner
P
P
Haddad
G
G
Gallie
B L
BL
Ling
V
V
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
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D008562:Membrane Glycoproteins