Assignment of two human epidermal squamous cell carcinomas cell lines to more than one complementation group for the...

Two human cell lines derived from squamous cell carcinomas (SCCs) of the epidermis, SCC-12 clone F and SCC-13 clone Y, were made to be independent of the Swiss 3T3 feeder layer to perform somatic-cell genetic experiments. We fused these SCC lines with normal human fibroblasts, and all resulting hybrids senesced after completing 12-17 population doublings, suggesting that in part, immortalization of the keratinocyte during SCC development results from the loss of gene function. We also tested whether these two SCC lines mapped to known complementation groups for immortality by fusing them with representatives of groups A (GM847), B (HeLa), and C (143B), but most of these hybrids were indistinguishable from those derived from homotypic crosses set up as immortal hybrid controls. As reported by others, fusions of cell lines from different complementation groups-143B (group C) x HeLa (group B) or GM847 (group A) x Hela (group B)--resulted in predominantly senescent hybrids. Our results confirmed and extended previous observations by others that the phenomenon of senescence is dominant to that of immortality, but they did not allow us to assign either of the SCC lines we studied to a complementation group for immortality.