The Study Of Apoptosis After Cell Differentiation Induced By Retinoid Acid

BACKGROUND AND OBJECTIVE:Cell diferentiantion is a key problem in cell biology. RA (Retinoic acid) is a powerful cyto-differentiating agent. The compound is successfully used in the treatment of acute promyelocytic leukemia (APL). Previous studies suggested that the mechanism of treating premyeloid leukemia with RA is inducing premyeloid leukemia cells to differentiation along the myelocyte lineage,but the mechanism how the tumor cells were eliminated and the relationships of cell cycle regulation , cell differentiation and apoptosiscific still remains unknown. This sduty was to establish a stable cell cycle specific model induced by Retinoid Acid in vitro, so as to provide a reliable platform to investigate the relationship between the differention of HL60 cells induced by RA and apoptosis.In addition, CDKs are the core kinase in Cell-Cycle machine. The present study was to explore the potential regulatory role CDKs on Apoptosis.MATERIAL AND METHODS:HL60 cells were incubated with Retinoid Acid for 96 hours,then were washed and cultured in RPMI 1640 media for 6-24 hours.Apoptosis was detected by sub-G1, traditional Annexin-V/PI and improved API methods and analysed by flow cytometry, and establish the stable cell apoptosis model. Then, part of the cells which were incubated by Retinoid Acid for 96 hours and washed ,were added Roscovitine to inhibit activity of CDK1 , analysed apoptosis of these cells. Cyclin B assay were proceeded on Flow Cytometry to analyze Cell Cycle.RESULTS:With drug-inducing time increacing, the effect of cell arrest increased gradually. when HL-60 cells were washed after incubated with Retinoid acid for 96 hours, apoptosis rose with the time increased. Apoptosis occurred in G1 phrase. Inhibition of CDK1 activity also inhibited G1 specific apoptosis.CONCLUSION:Retinoid acid can induce the differentiation of HL60 cells. The differentiated cells are easy to apoptosis, and this apoptosis was cell cycle-specific and initiated at G1 phase. Inhibition of CDK1 activity also inhibited G1 specific apoptosis.