Vincristine-resistant human leukemia cell line: new monoclonal antibodies to a 65kDa membrane protein

A vincristine-resistant human myelomonocytic leukemic cell line (KY-VCR) was established. KY-VCR exhibited approximately a 2.5 x 10(6)-fold increase in resistance to vincristine compared to the parental cell line. KY-VCR showed a decreased uptake and, an increased efflux of vincristine, and cross-resistance to Adriamycin and Actinomycin D. The M(r) 200,000 membrane glycoprotein was overexpressed in KY-VCR. Furthermore, two antibodies, designated TO73 and TO77, preferentially reacting with KY-VCR were obtained. Enzyme linked immunosorbent study indicated that both antibodies recognized the same epitope and TO77 the wide portion. Immunoprecipitation analysis demonstrated that the antibodies recognized M(r) 65,000 membrane protein, which was distinct from overexpressed glycoprotein in KY-VCR. The induction of membrane protein identified by the antibodies may play a role in drug resistance. KY-VCR cells and two antibodies to them may be very useful for the study of drug resistance and prediction of drug efficacy.