Characterization of human keratinocyte X HeLa somatic cell hybrids.

Intraspecific human cell hybrids were created by fusing normal epidermal keratinocytes with carcinoma (HeLa) cells. All of the hybrids were epithelial in morphology and exhibited a bright cytoskeletal pattern after indirect immunofluorescent labelling by antibody against keratin. Like the normal parental cells, the hybrid populations had organized arrays of microfilaments, and expressed low levels of surface fibronectin, predominantly in short "stitches" at cell boundaries. None of the cells expressed collagen type I, as expected of epithelial cells. Subcutaneous injection into nude mice revealed that the tumorigenic phenotype was initially suppressed in certain of the hybrids. However, cells of these lineages tested at later population doublings, and other hybrid clones tested at early population doublings, formed very small, non-progressive nodules, Histologically, these nodules resembled moderately to well-differentiated squamous-cell carcinomas. The properties in vitro and in vivo of these epithelial hybrids are compared to those of human fibroblast X HeLa hybrids.