[Artificial selection for increased metastatic potential in cell population of transplanted rhabdomyosarcoma RA-2 in...

The rhabdomyosarcoma was induced with 20-methylcholanthrene in unbred white rat; it was selected for the metastatic potential (MP)--the ability to form experimental lung metastasis after i. v. injection of tumor cells. After 10-15 cycles of selection there was 100-fold increase in the level of MP, all the tumor cells acquired simultaneously the affinity to the lung tissue. After that the tempo of selection decreased. From 112-124 to 177-183 cycles of selection the frequencies of MP-cells in the population were increased only 10-fold (from 0.007 to 0.06). High level of karyotypic and phenotypic heterogeneity persisted in the selected cell population, the differences for MP between clones were great. It was shown the heritable instability of the character "the MP-level" in the selected cell population.