Genetic analysis of tumorigenesis: XII. Genetic control of the anchorage requirement in CHEF cells.

Chinese hamster somatic cell hybrids between diploid anchorage-independent CHEF/204Bu50 cells and diploid anchorage dependent CHEF/205-30 cells are anchorage dependent but can segregate subclones at low frequency which reexpress anchorage independence. Thus, anchorage independence, like other characteristics of the transformed phenotype, is suppressed in these hybrids. Anchorage-independent subclones were recovered from the anchorage-dependent hybrids under conditions which favored the retention of most chromosomes. Karyotype analysis of suppressed hybrids and their anchorage-independent subclones showed that segregation of anchorage dependence was correlated with the loss of one copy of chromosome 1 in CHEF Chinese hamster hybrids. Thus, suppression of anchorage independence has a chromosomal basis. Several genetic models are considered for the origin of anchorage-independent subclones from suppressed Chinese hamster hybrids.