EFFECTS OF PROMOTERS ON DNA-SYNTHESIS IN C3H-10T1-2 MOUSE FIBROBLASTS

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (9) , 3223-3227
Abstract
The synthesis of DNA was studied by autoradiography and measurements by 3H-thymidine ([3H]TdR) incorporation in cultured C3H/10T1/2 mouse embryo fibroblasts. The cells were first treated with 3-methylcholanthrene as an initiator and then with promoters according to schedules that produce oncogenic transformation. The levels of 3-methylcholanthrene used did not affect the growth or [3H]TdR incorporation of the cells. Treatment during the log phase of growth with 12-O-tetradecanoyl-phorbol-13-acetate, phorbol didecanoate or 4.alpha.-phorbol didecanoate produced a transient inhibition of [3H]TdR incorporation with the maximum at 12 h after treatment. This resulted in a temporary delay of growth followed by recovery of the normal cell doubling time. Phorbol did not produce these effects, suggesting that the inhibition of DNA synthesis is associated with the process of promotion. Although treatment of the cells with 12-O-tetradecanoyl-phorbol-13-acetate during the stationary phase resulted in a 2- to 3-fold stimulation of [3H]TdR incorporation, multiple treatments spanning log and stationary phases were necessary for promotion.