Detection of p53 Protein in Leukemic Cells by Flow Cytometry.

Although the alterations of TP53 gene are rare in malignant hematological disorders, these genetic alterations have strong correlations with unfavorable prognostic factors and are found in relapse acute lymphoid leukemia (ALL), relapse acute myeloid leukemia (AML), blastic crisis of chronic myeloid leukemia (CML) and evolution from chronic lymphoid leukemia to Richter’s syndrome (CLL/SR). Most methods currently used to study TP53 gene employ molecular biology techniques such as single strand conformation polymorphism (PCR-SSCP) and direct DNA sequencing. Both techniques detect TP53 gene mutation but not p53 protein expression and are time-consuming and difficult to apply in the clinical setting. In the last years, p53 protein expression has emerged as a potential prognostic marker, which can be used to study TP53 gene alterations in malignant diseases. The aim of this work was to validate flow cytometry (FC) technique to detect p53 expression in different types of leukemias and analyze the relationship between p53 expression and status of disease. We studied p53 protein expression in 223 blood and bone marrow samples: 72 patients with CML, 54 in chronic phase (CML-CP), 7 in accelerated phase (CML-AP) and 11 in blastic crisis (CML-BC); 64 patients with CLL (34 at diagnosis and 9 with Richter’s syndrome), 44 patients with ALL (36 at diagnosis and 8 in relapse) and 43 AML (27 de novo, 7 in relapse and 9 secondary AML). p53 protein expression was observed in 63 out of 223 patient’s samples: 14/64 CLL (21.9%), 13/44 ALL (29.5%), 19/43 AML (44.2%) and 17/72 LMC (23.6%). The highest levels were detected in the advanced phases of CLL, ALL and CML. In addition, in AML cases, high levels of p53 expression were detected in secondary and relapse disease and also in de novo AML cases. Our results demonstrated that p53 expression levels are strongly associated with advanced disease. Based on these results flow cytometry can be a reliable approach to study p53 protein expression in leukemic patients. Further studies are needed to ascertain the role of p53 expression as a prognostic marker of disease progression.