Rearrangement and expression of MDM2 oncogene in chronic lymphocytic leukemia

Since trisomy 12 is the most common chromosome abnormality found in CLL and MDM2 has been mapped to this chromosome, we examined the possible association of MDM2 in the pathogenesis of CLL. A rearrangement of the MDM2 gene was observed in 4 of 11 peripheral blood mononuclear cells (PBMC) from patients with CLL by Southern blot hybridization. Expression of MDM2 was detected in all of the CLL samples examined by Northern blot. However, neither gross amplification nor overexpression of the MDM2 gene was found in CLL. The data suggest that MDM2 may play a role in the pathogenesis of CLL and may help to explain how abnormalities of chromosome 12 are related to CLL.