Abstract

Multidrug resistance (MDR) phenotype is frequently observed in animal and human cancer cell lines selected for in vitro resistance to a single chemotherapeutic agent. It is characterized by the diminished j drug accumulation and is related to the drug efflux mechanism in resistant cells. In the present study, adriamycin resistant cells (L1210-AdR6: 10-6M adriamycin, -AdR5: 10-5M) and vincristine resistant cells (L1210-VcR7: 10-7M vincristine, -VcR6: 10-6M) were produced from mouse lymphoblastic leukemia cell line L1210. Growth profiles of survived cells were observed for 5 days with MTT (thiazolyl blue) assay and resistance was compared with IC50 (drug concentration of 50% survival reduction in absorbance). Resistant cells proliferated more slowly than sensitive cell. Doubling times were 29.7hr in L1210, 68.7 hr in L1210-AdR5 and 58.2 hr in -VcR6. MDRs expressed as resistance factor were as follows, L1210-AdR5 was 76.4 times for vincristine, L1210-VcR6 was 96.4 times for adriamycin. The cell membrane proteins with three different M.W. were recognized to be related resistance, 220, 158, and 88 Kd in L1210-AdR5, 158, 140 and 88 Kd in L1210-VcR6 by SDS-PAG electrophoresis. Cell surface membrane proteins were identified by radio-iodination and autoradiogram. Their molecular weights were 158, 72.8, and 42.4 Kd in L1210-VcR6.

• Keywords: MDR, MTT, Cell surface membrane protein;