[Clonal analysis of karyotypic instability and metastatic potential in tumor cell populations]

Rat organospecific transplantable RA-2 rhabdomyosarcoma strains RA-2H and RA-2L were investigated using single cell cloning technique for "Micronuclear containing cell frequency" (MCF) and "Metastatic potential" (MP). The RA-2H was obtained from RA-2 during selection for increasing metastatic potential, whereas the RA-2L was the result of selection in opposite direction. MP was assessed by lung colony formation technique and in the case of RA-2H, it was one hundred times greater than in the case of RA-2L (2490 +/- 280 and 22 +/- 11 lung colonies i.v. after injection of 10 cells, respectively). Average MCE for RA-2H was 3 and for RA-2L 5.3%. Also, significant differences were observed between these substrains in percentage of anaphase and telophase cells with bridges and fragments (24 +/- 4 for RA-2H and 56 +/- 5% for RA-2L, P less than 0.05). The selection of RA-2H clones with high level of MCF was successful. In the population obtained MCF was increased up to 7.8% and MP decreased (79 +/- 44). So, the selection for decreasing of MP led to significant increase in genome instability characteristics and the selection for increasing of MCF--to the abrupt decline of MP, which proved the existence of negative correlation between these two characters in populations studied. It is concluded that correlation between malignancy and genome instability in tumor populations with different levels of malignancy is not, as a rule, positive.