Specific chromosomal aberrations correlated to transformation in Chinese hamster cells.

Cytogenetic changes were investigated during the spontaneous progression of CHEF18 Chinese hamster cells towards tumorigenicity. We further report the chromosomal characterization of a series of spontaneous anchorage-independent clones, as well as of a series of tumor-derived cell lines resulting from injection of late passage cells in nude mice. The high karyotypic homogeneity (presence of four marker chromosomes strictly associated in all the metaphases analyzed) in all clones and tumor-derived cell lines prompted us to alter the specific pattern of chromosomal aberrations in order to identify which if any of the aberrations were more strictly related to transformation. For this purpose we treated a tumor-derived cell line with Colcemid and analyzed the reversion of anchorage-independent phenotype in the subclones showing an altered association of the four marker chromosomes. We conclude that two of four marker chromosomes contribute to anchorage independence.