title: Spontaneous neoplastic transformation in vitro of a diploid clone of rat liver cells under conditions of large inoculum size of cells at the transfer.
abstract: Attempts were made to examine the correlation of the chromosomal stability and neoplastic transformation with routine subculturing at small and large inoculum sizes of cells. A diploid clone of rat liver cell, Ac7E, was put on a rigid transfer schedule, being transferred every 10 days, and inoculated always at the same cell density or the same split ration. The cells which were subcultured before confluency did not undergo spontaneous neoplastic transformation and maintained diploid karyotype for at least 117 generations (356 culture days) after cloning. However, transformation occurred when cells were transferred for more than 49 generations (265 days) after cloning at a large inoculum size of cells and maintained in the confluent state for a while before subculturing. The transformed cells showed the high saturation density and a multilayered growth pattern in culture. G-band analysis of chromosomes demonstrated the preferential involvement of a complete or partial trisomy of #1 chromosome in a transformed cell line, also in cell lines which were reestablished from induced tumors by the backtransplantation of transformed cells.
mesh_terms: D000818:Animals; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D002999:Clone Cells; D005260:Female; D007621:Karyotyping; D008099:Liver / Q000473:pathology* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D014314:Trisomy