Normalization of the phenotype of transformed Djungarian hamster cells during selection for colchicine resistance

The range of the Djungarian hamster cell lines selected for colchicine resistance in high doses (from 7 to 200 micrograms/ml) was studied. These cell lines are characterized by the different levels of drug-resistance (1000- to 16000-fold). A positive correlation is found between the reversion rate of malignant phenotype and the cellular drug-resistance level. Tumorigenicity and anchorage independence decrease with an increase of the drug-resistance level. The actin-containing bundles of microfilaments in more resistant cells are more organized. The 22 kD protein content increases with the drug-resistance level. The mechanisms of malignancy reversion are discussed.