Evidence for genetic determinants of susceptibility to tumor promotion has come from the observation that mice can be bred for increased or decreased sensitivity to skin tumor pro motion without coselection for parameters associated with tu

Transfection of activated promotion sensitivity genes(pro genes)con fers on insensitive (P) cells susceptibifity to induction of anchorage Independent growth by tamer-promoting phorbol esters. Promotion-sen sitive (P) JB6 cell variants, from which activated pm-i and pro-2 were cloned, res@ to 12.O-tetradecanoylpborbol-13-acetate (1PA)and var Ions noophorbol tumor promoters with anchorage-Independent transfer motion that is Irreversible 6040% of the time. Anchorage-independent (Tx)clonal lines derived from these TPA-induced agar colonies were also tumorigenic in nude mice. This report has addressed the question of whether the phenotypes associated with parental P@cells are transferred bytransfectionofactivatedpm-1andpro-2.aonal lineswereestablished after transfectionofJB6 P cells with activatedj,ro-1 orpro-2, induction of anchorage-independent colony formation by TPA, and growth of Individual apr colonIes to yield clonal transfectant lines. The lines so derived from transfected populations included Tx, P@,and P lines, reflecting Irreversible neoplastic transformation and greater and lesser degrees of preneoplastic progression, respectively. The anchorage-hide pendant transfeCtantswere found to be tumorigenic.Since untransfected Pcells subjected to the same single-cycleTPA treatment and cloningIn agar Yielded no anchorage-independentand few P@transfectants, the appearance of P@and Tx trnnsfectants afterpro-1 and pm-2 transfection Is therefore likely to be due to the transfected pro genes. Indirect assay ofpru gene uptake by quick-blot hybridizationof transfectant cell DNA with the vectors into which pro genes had been cloned confirmed the associationoftransferred P' and Tx phenotypeswith the presenceof the transfectedDNA. Finally, assayof the sensitivity of P@piv-1 andpro-2 transfectantsto transformation by TPA at variousconcentrationsshowed that trnnsfection with pro-i or pro-2 conferred about equal responses that weresomewhatlowerthan those observedwith parental P@controls. Taken together these data Indicate that promotIon-insensitive JB6 cells need only an activated pro gene and TPA exposure to become neoplasti cally transformed.