Expression of the retinoblastoma tumor suppressor gene (RB-1) in acute leukemia

In this report we review current studies concerning the RE-I gene expression in acute leukemias. The RE-I gene was analyzed in several studies by protein-, RNA and DNA-techniques in acute lymphoblastic leukemia (ALL);Is well as in acute myelogenous leukemia (AML). The frequency of RE-I inactivation in ALL-patients ranged between 30% and 64% in several studies. Structural abnormalities of the RB-1 gene were reported in 18% of ALL-patients and in 27% of Philadelphia chromosome-positive ALL, respectively, The proportion of AML-patients with absent RE-I protein expression ranged between 19% and 55%. Structural RB-1-abnormalities in AML were predominantly reported in leukemias with monocytic differentiation. Furthermore, the prognostic value of an abnormal RB-1 gene expression was also estimated in some studies. Ln childhood ALL RB-1 inactivation was reported to have prognostic significance while in contrast, in another study on adults no prognostic value of RE-I was found. In 4 out of 5 documented studies AML-patients with RB-1 inactivation generally had a poorer prognosis, In conclusion, RB-1 inactivation is frequently observed in acute leukemia. The prognostic value of low RB-1 expression is controversial but the majority of published studies found low RB-1 expression to be a negative I,prognostic predictor, in acute leukemia.