2004 Volume 27 Issue 7 Pages 992-997
All-trans retinoic acid (ATRA) differentiates HL-60 cells into granulocyte-like cells and cellular proliferation is repressed markedly along with the morphological and physiological changes specific for cellular differentiation. To elucidate the implication of cyclin-dependent kinase (CDK) inhibitors during differentiation, we examined the expression of CDK inhibitors during the differentiation of HL-60 cells. The expression of p21 and p27 among the CDK inhibitors we examined increased during the differentiation induced with ATRA. Then, we established stable transformants of HL-60 cells expressing antisense RNA for p21 and p27 and examined the ability of these cells to differentiate into granulocyte-like cells. The extents of fully differentiated HL-60 cells transfected with genes for antisense RNA of p21 and p27 were only 53% and 60%, respectively, whereas 90% of the parental HL-60 cells differentiated by the ATRA treatment. These results suggest that increased expression of CDK inhibitors, p21 and p27, is necessary for the differentiation of HL-60 cells induced with ATRA.
