Objective: To investigate the clinical significance of cyclin A expression in adult patients with acute leukemia (AL).
Methods: 4 ml bone marrow was extracted from 100 AL patients and 10 normal controls to isolate the mononuclear cells (MNCs). The cyclin A mRNA levels in these MNCs were measured by RT-PCR. The cyclin A protein level and cell cycle in 75 randomly selected AL patients and 10 normal controls were examined by flow cytometric analysis.
Results: (1) The distribution of cyclin A protein was normal in cell cycle in AL patients. The positive rates of cyclin A protein and mRNA were 66.7% and 59%, significantly higher than those in the normal controls (0 and 1.4% respectively, both P < 0.01). The median expression levels of cyclin A protein and mRNA of cyclin A in AL patients were 18.5% and 0.539 +/- 0.490 respectively, significantly higher than those in the normal controls (both P < 0.01). Sequence analysis showed a complete consistency between the positive segment of cyclin A and the objective gene in GeneBank. (2) The levels of cyclin A protein and mRNA were positively correlated with the cumulative percentages of cells in S and G(2)/M phases (P < 0.01). (3) The expression level of cyclin A protein in the recurrent acute lymphoblastic leukemia (ALL) group was 15.4%, significantly lower than those of de novo group (29.5%, t = 14.418, P = 0.022). (4) The complete remission (CR) rates in the AL patients with high expression levels of cyclin A protein and mRNA group were 87.9% and 85.7% respectively, significantly higher than those in the AL patients with low expression levels (38.2% and 53.5% respectively, both P < 0.01). Multivariate regression analysis showed that cyclin A was one of the influencing factors of CR rate of AL patients (P < 0.05).
Conclusion: Cyclin A expression contributes to the high proliferative activity in leukemia cells. The abnormal expression of cyclin A might be a prognostic marker of CR rate in AL patients.