[Activation of ras oncogene in myelodysplastic syndrome and acute myelogenous leukemia]

N-ras oncogenes activated by point mutation have been frequently detected in various types of human leukemias. Analysis of a large number of leukemias revealed that activated N-ras oncogenes were observed preferentially in AML, AMoL, T-ALL and Null-ALL but rarely in CML and B-cell leukemia. These results suggest that N-ras oncogene plays an important role in human leukemogenesis. Activated N-ras oncogenes were also detected in myelodysplastic syndrome (MDS) that is considered to be a preleukemic disease. MDS patients bearing an activated N-ras oncogene frequently showed leukemic progression of the disease, suggesting that an activated N-ras oncogene can be a critical factor for prognosis of MDS patients. Thus, detection of an activated N-ras oncogene is useful for diagnosis, prognostic evaluation and therapeutic decision. Recently, we demonstrated that detection of the minimal residual disease by analysis of N-ras oncogene can lead to improvement of the remission rate in leukemias. Moreover, we made it possible to screen N-ras oncogene by a sensitive non-radioactive method. Our research procedure seems to be a good model for clinical application of the molecular biological technique.