Clonal analysis of diversity in the BSp73 rat XXXX .

@entity5 @entity843 @entity981 @entity5427
By implantation of BSp73 @entity843 cells in a subcutaneous site and subsequent subcutaneous passage of either the local @entity5 node or metastatic lung tissue, variants were obtained which differed with respect to morphology and to metastatic capacity. The highly metastasizing variant ASML showed spherical morphology in culture, while the nonmetastatic variant @entity5427 showed adhesion and spreading. Upon cloning it was observed that colonies with fully expressed morphotypes were readily obtained from solid tissue of both variants. Parental @entity843 as well as the @entity5 line derived from the primary solid @entity5 gave rise to stable expression of either morphotype only after prolonged culturing. Mixing of established clones did not result in an interclonal adaptation of growth rates in vivo. Further characterization of variants @entity5427 and ASML revealed marked differences in the outer cell surface. Adhesion of @entity5427 cells onto plastic was found to be mediated by fibronectin, laminin and 4 out of 5 collagen types. ASML cells showed adhesion only with collagen type III at higher concentrations. Cytogenetic analysis revealed that the adaptation of BSp73 cells to ascitic growth ultimately led to an increase in chromosome numbers, and this was conserved in ASML cells (modal number 63, range 49-74). @entity5427 cells on the other hand showed a modal number of 47 (range 45-49). The chromosome count distribution was rather narrow in @entity843 cells in vivo, but it was very broad in clones derived thereof, indicating that diversity was obtained in culture rather than in vivo. The data are compatible with the assumption that the nonmetastatic variant was not preexisting in BSp73 @entity843 but represents a stable phenotype which infrequently arises in a particular microenvironment by chromosome loss from a @entity981 parental population.
