The fate of the primary diploid population during spontaneous transformation of growth factor‐supplemented murine cell cultures

Abstract

Primary cultures derived from lung and renal tissue of the newborn harvest mouse (Micromys minutus) were serially passaged in media supplemented with epidermal growth factor, hydrocortisone, transferrin, insulin, and triiodothyronine. Although these growth factor supplements eliminated the growth crisis commonly encountered during the initial stages of murine primary cultures, the original diploid cell fraction clearly underwent such a “crisis”; the truly diploid cells invariably disappeared as these cultures reached 20 to 40 population doublings. They were replaced, either gradually or precipitously, by various heteroploid cell fractions. In three of four independent cultures, these “established” cells were hypotetraploid and appeared to be derived from a small number of progenitors already present during the very early (precrisis) culture stages. In contrast to rather frequent DNA changes displayed by clones and subclones derived from the various heteroploid cell lineages, the predominant components of the established mass cultures displayed a highly constant DNA fluorescence pattern. Our results suggest that primary murine cell cultures develop heteroploid cell lineages even if the initial growth crisis is mitigated by growth factor supplements. These heteroploid cells appear to respond more efficiently to stimulation by various growth factors than the primary diploid cell population.

Characterization of Transformed Cell Lines Evolving from a Normal C3H Line

“…The spreading of the peaks in DNA his tograms suggests the presence of subclones with unresolvable differences in DNA con tent, as observed by other authors [Kubbies et al, 1986], However, at later passages of A and B lineages, stable subpopulations with near tetraploid DNA contents were se lected.…”

Dna ploidy status and DNA content instability within single tumors in renal cell carcinoma

“…This clonal evolution of tumors has already been observed in cell lines and in transplantable tumors (2,10,11). It is particularly well documented in the transplantable prostatic tumors of the Dunning system where duplication of the genome is associated with a markedly increased growth rate and dedifferentiation, whereas subsequent chromosomal losses are associated with attainment of metastatic ability (22).…”

“…However, the mechanism by which aneuploidy influences the aggressive behavior remains elusive (9). In vitro studies (2,10,11) suggest that diploid tumor cells can become aneuploid by first doubling their chromosome set leading to an unstable tetraploid genotype, followed by subsequent chromosome loss. This phenomenon could contribute to tumor progression by generating cells with a new genotype.…”