Prognostic significance of the cell cycle inhibitor p27(Kip1) in acute myeloid leukemia

There are few molecular biologic determinants that are prognostic for patie nts with acute myeloid leukemia (AML). Hence, we examined whether cellular levels of the cyclin-dependent kinase inhibitor p27(Kip1) in acute myeloid leukemia could be used to predict clinical outcome in AML. Using immunoblot analysis, levels of p27 were assessed in blast cells from 72 AML patients who were registered and treated by the identical chemotherapy protocol. AML cases were classified into three groups on the basis of the percentage of the expression level of p27 compared to a control cell line. AML cases exhi biting p27 expression at low, moderate, and high levels were 43, 9, and 20 cases, respectively. No significant differences in the rates of complete re mission (CR) were observed among the three groups. Although the level of p2 7 expression was not correlated with any other possible prognostic markers, such as age, white blood cell count, chromosome abnormalities, and FAB sub classes, patients with high p27 expression had a significantly increased di sease-free survival (DFS) (78% vs 19%, P = 0.004). We further examined the expression of cyclin E at the protein level in all 72 AML cases. We observe d a statistically significant correlation between a high cyclin E level and a high p27 level (P < 0.005). However, we failed to find any correlation b etween the rates of CR or DFS and cyclin E expression. The present study re veals that levels of p27 expression can be one of the useful prognostic mol ecular markers for AML.