LACK OF MDM2 AMPLIFICATION IN HUMAN LEUKEMIA

While deletion or mutation of the p53 gene is one of the most common m olecular alterations detected in a wide variety of tumours, it has bee n shown to occur in only a relatively small percentage of the leukaemi a cases examined. However, it may be that other components of the p53 pathway are involved. Amplification of the MDM2 gene has recently been demonstrated in human sarcomas resulting in an increase in MDM2 prote in levels. This protein can bind to p53 preventing the transactivation of p53 responsive genes, thus mimicking mutation or deletion of p53. We have investigated the prevalence of MDM2 amplification in human leu kaemias. 101 leukaemia or lymphoma samples and nine cell lines were st udied using Southern blotting. In no case was MDM2 amplification prese nt. We conclude that MDM2 amplification is not a common event in human leukaemias.