Overexpression of Bcl2 protein predicts chemoresistance in acute myeloid leukemia: Its correlation with FLT3

Abstract

Potential prognostic biomarkers in acute myeloid leukemia (AML) can be identified by understanding the cellular pathway and molecular changes underlying leukemogenesis. Deregulation of apoptosis is one of the important features of AML and to understand the molecular mechanism underlying apoptosis and its contribution to tumor progression, this study aimed to evaluate anti-apoptotic Bcl2 protein expression in AML and correlate with FLT3 parameters for their role in prognosis of disease.Bcl2 and FLT3 protein expression was quantified by flow cytometry on leukemic blasts in total 174 de novo AML, myelodysplastic syndrome (MDS) and aplastic anemia patients. FLT3 internal tandem duplication (ITD), Tyrosine kinase domain (TKD) point mutations and quantification of mRNA level was carried out using PCR and RT-PCR methods. The incidence of Bcl2 positivity was 71% in AML patients. Bcl2 positivity was significantly associated with CD34+ and CD117+ AML. Bcl2 positivity tended to be associated with reduced DFS while Bcl2 positivity with FLT3 protein positivity was significantly associated with reduced DFS. In multivariate analysis, Bcl2+ and combined Bcl2+/FLT3 protein+ along with high WBC count emerged as poor prognostic factors for reduced DFS and high blast count for predicting reduced OS. In MDS patients, the incidence of Bcl2 expression was high while in aplastic anemia patients, incidence of Bcl2 expression was low.Patients with Bcl2 and FLT3 protein positivity showed significantly reduced DFS suggesting parallel role of these proteins in imparting chemoresistance to the leukemic cells.