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Differential effects of TPA and pristane on gene expression and transformation in mouse epidermal cells
L R Garrett1, C E Ackland-Berglund, C J Jones
1Department of Microbiology, University of Mississippi Medical Center, Jackson 39216-4505.
Abstract:
The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) or 2,6,10,14-tetramethylpentadecane (pristane) on gene expression and transformation were examined using two clones (P+, TPA transformation sensitive and P-, TPA resistant) of the mouse epidermal cell line JB6. Results from transformation studies indicated pristane was more efficient, i.e., lower concentrations were required to elicit an equivalent response, in transforming the P+, but not the P-, clone of JB6 compared to TPA. Furthermore, results from these studies demonstrated either TPA or pristane was effective in the transactivation of the chloramphenicol acetyltransferase gene under the regulatory control of most viral promoter/enhancer elements transfected into the P+, but not the P-, clone of JB6. However, if a consensus cAMP response element was linked to the simian virus 40 early promoter, pristane activation was observed in both P+ and P- cells. The differential effects of these two compounds suggest that while they have similar characteristics, they may utilize different pathways to elicit their effects.
Insights
Pristane and 12-O-tetradecanoylphorbol-13-acetate (TPA) affect mouse epidermal cell transformation differently. Pristane is more efficient than TPA, suggesting distinct molecular pathways are involved in their cellular effects.
Area of Science:
- Cell biology
- Molecular toxicology
- Chemical carcinogenesis
Background:
- 12-O-tetradecanoylphorbol-13-acetate (TPA) is a known tumor promoter.
- Pristane is a saturated hydrocarbon with potential tumor-promoting activity.
- Mouse epidermal JB6 cell lines (P+ and P-) offer a model to study chemical-induced cell transformation and gene expression.
Purpose of the Study:
- To compare the effects of TPA and pristane on JB6 cell transformation.
- To investigate the impact of TPA and pristane on gene expression.
- To elucidate the molecular pathways utilized by TPA and pristane.
Main Methods:
- Transformation assays using P+ and P- JB6 cell clones.
- Gene expression analysis using chloramphenicol acetyltransferase (CAT) reporter assays.
- Transfection of JB6 cells with constructs containing viral promoter/enhancer elements and a cAMP response element.
Main Results:
- Pristane demonstrated higher transformation efficiency than TPA in P+ JB6 cells, with no effect on P- cells.
- Both TPA and pristane induced transactivation of CAT gene expression driven by most viral promoters in P+ cells, but not P- cells.
- Pristane induced CAT gene expression in both P+ and P- cells when a cAMP response element was linked to the simian virus 40 early promoter.
Conclusions:
- TPA and pristane exhibit differential effects on JB6 cell transformation and gene expression.
- The distinct responses suggest that TPA and pristane may activate different intracellular signaling pathways.
- Pristane's activity, particularly in conjunction with a cAMP response element, indicates a complex mechanism of action that differs from TPA.