Cell cycle dependency of tumor promoter on murine erythroleukemic cells.

The tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) affected the cell cycle of murine erythroleukemic cells. In logarithmically growing cells a transient G1 block lasting approximately 6 hr developed after the addition of TPA. To investigate this cell cycle effect of TPA, cells were synchronized either by a double thymidine block or by centrifugal elutriation and were analyzed by flow cytometry and electronic nuclear volume. Using double thymidine blocked synchronized cells or elutriated separated fractions containing cells other than G1, a transient G1 block occurred as the cells entered early G1. The G1 elutriated cell population was blocked in the G1 period by TPA before cell cycle traverse. This transient block in G1 was not observed after the next cell cycle traverse. Addition of TPA to butyric acid or dimethylsulfoxide induced-cells resulted in a transient G1 block in addition to inhibition of differentiation. TPA was more inhibiting on dimethylsulfoxide-induced cells than butyric acid-cells.