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 expression of cyclin D1 using RT-PCR. In addition, the relationships of cyclin D1 to the retinoblastoma tumor suppressor gene and the Ki-67-expression were analyzed. Cyclin D1-mRNA was detectable in 42 out of 58 patients with de novo 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 D1 expression was independent of the proliferative activity of the cells and inversely correlated to the expression of the retinoblastoma tumor suppressor gene (r = -0.27, p = 0.03). Prognostic considerations using Kaplan Meier estimates for the relapse-free interval showed that patients with high cyclin D1- mRNA levels had a poorer prognosis (p = 0.046).