Analysis of cyclin D1 in de novo and relapsed childhood acute lymphoblastic leukemia

In a retrospective analysis we investigated 59 children with de novo acute lymphoblastic leukemia (ALL) and 28 patients with relapsed ALL for the expr ession of cyclin DI using RT-PCR. In addition, the relationships of cyclin D1 to the retinoblastoma tumor suppressor gene and the Ki-67-expression wer e analyzed Cyclin D1-mRNA was detectable in 42 out of 58 patients with de n ovo ALL (72%) and in 26 out of 28 relapsed patients (93%). The blast cells of the relapsed patients contained significantly higher levels of cyclin D1 -mRNA compared with the de novo group (p=0.0007). The cyclin DI expression was independent of the proliferative activity of the cells and inversely co rrelated to the expression of the retinoblastoma tumor suppressor gene (r=- 0.27, p=0.03). Prognostic considerations using Kaplan Meier estimates for t he relapse-free interval showed that patients with high cyclin D1- mRNA lev els had a poorer prognosis (p=0.046).