OVER-EXPRESSION OF THE MDM(2) GENE IS FOUND IN SOME CASES OF HEMATOLOGICAL MALIGNANCIES

We looked for MDM(2) gene amplification and over-expression by Souther n and Northern blot analysis in 135 and 66 cases of haematological mal ignancies, including ALL, AML, CML in chronic phase, CLL, MDS, PLL, no n-Hodgkin's lymphoma (NHL) and myeloma. No amplification of the gene w as found. An over-expression of MDM(2) RNA was seen in 9/66 (14%) pati ents tested, including 3/9 ALL, 3/24 AML, 2/4 myelomas, 1/1 PLL, but 0 /2 CML, 0/2 NHL and 0/21 MDS. None of the patients over-expressing MDM (2) had modifications of P53 gene transcript or p53 mutations. Most of the patients over-expressing MDM(2) gene had poor prognostic features (including 'unfavourable' cytogenetic abnormalities), poor response t o chemotherapy and short survival. Our findings suggest that over-expr ession of MDM(2) is seen in a relatively small number of haematologica l malignancies, and is associated with poor prognosis.