Transfer of Sensitivity to Tumor Promoters by Transfection of DNA from Sensitive into Insensitive Mouse JB6 Epidermal Cells

Publisher Website
Google Scholar
Abstract
Sensitivity to promotion of transformation by tumor promoters in mouse epidermal JB6 cells appears to have a genetic basis since the phenotypes of both promotable and nonpromotable JB6 cells derived from a common parent line are stable. Hybridization of promotable (P+) and nonpromotable (P−) cells previously indicated that promotability appears to behave as a dominant trait. These results suggest that it should be possible to find DNA sequences which specify sensitivity to promotion of anchorage independence by 12-o-tetradecanoyl-phorbol-13-acetate (TPA). Cellular DNA isolated from one of two P+ lines, JB6 Cl 41 or JB6 Cl 22, was CaPO4 precipitated and used to transfect the P− cell line JB6 Cl 30. At 7 days posttransfection, the cells were suspended in agar with or without TPA at 1.6 × 10−8 M and assayed 10 days later for TPA-dependent colony formation. Untreated or Cl 30 DNA-treated P− JB6 Cl 30 cells yielded 40 to 50 colonies per 105 cells. In contrast, transfection of Cl 30 cells with “P+ DNA” derived from either Cl 41 or Cl 22 yielded 200 to 500 TPA-induced colonies per 105 cells, or a five- to eightfold enhancement of promotability. The enhanced promotability obtained after transfection with P+ DNA was stable, as judged by the retention of promotability for at least eight passages in cell lines derived from TPA-induced agar colonies. Other transfectants showed irreversible transformation by TPA, as observed in the parental P+ lines. When NIH 3T3 cells instead of the putative preneoplastic JB6 Cl 30 cells were used as recipients for transfection of P+ DNA, no evidence for acquisition of promotability was obtained. P− JB6 Cl 25, like Cl 30, also permitted expression of transfected P+ DNA. These results suggest that sensitivity to phorbol ester promotion of transformation in JB6 cells is determined by DNA sequence(s) present in the P+ DNA and requires recipient cells of the appropriate phenotype for expression.