CHROMOSOMAL CHANGES DURING THE ACQUISITION OF RESISTANCE TO ADRIAMYCIN IN TUMORIGENIC HUMAN SYNOVIAL-CELLS

Chromosome analysis of tumorigenic human synovial cells at different s tages of acquisition of resistance to doxorubicin was undertaken. Expo sure of the sensitive cells to adriamycin for 2h induced chromatid abe rrations, while exposure to the drug for 6h did not show any mitosis. However, drug resistant cells continued to show high frequency of mito sis even in presence of the drug. High frequency of chromatid exchange s were seen during the process of the development of drug resistance b y exposure to increased drug concentration. Double minutes, a characte ristic feature of resistant cells appeared only when the drug resistan ce was established in the cells, which was confirmed by drug sensitivi ty assay.