Overexpression of MDM2 in Acute Childhood Lymphoblastic Leukemia

Abstract

Mutation of the TP53 gene is one of the most common molecular alterations in a variety of tumors, but it occurs infrequently in childhood and adult hematological malignancies. Protein accumulation often results from mutations that lead to inactivation of the p⁵³ protein. Other causes of functional inactivation of the p⁵³ protein include stabilization of p⁵³ via proteins such as MDM2, an oncoprotein capable of forming specific complexes with p⁵³. In the present study, protein expressions of MDM2 and p⁵³ were investigated by immunohistochemistry from bone marrow samples in 23 patients with acute lymphoblastic leukemia aged 1–13 years at diagnosis. P⁵³ protein overexpression was detected in only one case, while overexpression of MDM2 was detected in samples from five patients. All five patients overexpressing MDM2 belonged to a group with unfavorable prognostic signs at diagnosis and three of them relapsed or died within 6 months after diagnosis.

Key Words:

• childhood acute lymphoblastic leukemia
• interaction
• MDM-2
• p⁵³
• prognosis