A recently described system for monocyte-like differentiation of HL-60 cells was utilized to determine if the initiation of this pathway can be linked to a set of replicative cellular events. The standard induction system consisted of a 4-h exposure to 100 nM 1-a,25-dihydroxyvitamin D3 [1,25(OH)2D3] followed by determination of nonspecific esterase and phagocytic activity 24 h later. The cell cycle status was ascertained by the incorporation of [3H]thymidine and autoradiography. Studies in which cell cycle block in the d/S phase boundary region was produced by a partial inhibition of DNA synthesis with thymidine, or sodium butyrate, showed that the exposure of such semisynchronous cultures to 1,25(OH)2D3. resulted in an increased proportion of differentiated cells. Conversely, blocking the cell cycle with vinblastine (G2/M block) or theobromine (mid-d block) inhibited the initiation of differentiation by 1,25(OH)2D3. Experiments in which th§ differentiated cells were examined for the cell cycle position at the time of the exposure to 1,25(OH)2D3. by [3H]thymidine labeling and autoradiography confirmed that the late G1 and early S phase cells are those which predominate in the differentiated fraction of 1,25(OH)2D3-treated HL-60 cultures. These results link pre- and early replicative cellular events to the induction of monocytic differentiation by 1,25(OH)2D3.
|Original language||English (US)|
|Number of pages||8|
|State||Published - Aug 1 1985|
All Science Journal Classification (ASJC) codes
- Cancer Research