The Clinical Study And Mechanistic Exploration Of BCL11A In Myeloid Leukemia

Objective:Myeloid leukemia is a highly heterogenous group of hematologic malignancy, characterized by complex genetic, morphologic and immunophenotypic features. The pathogenesis of leukemia is mostly attributable to genetic abnormalities, such as chromosomal translocations, DNA mutations, aberrant gene expression, etc. Currently, new molecular markers are in great need to suit for the increasingly sophisticated diagnosis and prognosis of the disease. Rational treatments also require further developments, likely through identification of novel molecular targets, to achieve significant therapy benefits. The B-cell leukemia 11A gene (BCL11A) was initially identified from chromosomal translocations involving the immunoglobulin heavy chain locus detected in human B-cell non-Hodgkin lymphomas and by retroviral insertions in murine leukemia. It encodes a Kruppel-like zinc-finger protein containing three C2H2 zinc finger motifs, a proline-rich region, and an acidic domain. BCL11A primarily acts as a transcriptional regulator via directly binding to a guanine cytosine (GC)-rich DNA motif. BCL11A is expressed predominantly in the brain, hematopoietic cells, immune system and testis, and plays an important role in the development. Abnormalities of BCL11A have been connected to malignancies. Research on BCL11A has recently attracted a growing attention, given the remarkable appreciation of its regulation of hemoglobin expression. Previous work, including ours, has also implicated dysregulation of BCL11A in a variety of malignant hematopoiesis. However, BCL11A expression in patients with leukemia remains to be investigated. In this study, we examined the levels of BCL11A expression in AML and CML patients, using TaqMan real-time quantitative PCR technology. We suggest BCL11A aberrant expression may be a potential biomarker for diagnosis and prognosis of human myeloid leukemia.Methods:Leukemic blast cells were isolated from bone marrow of newly diagnosed 292 patients with AML and 73 CML with ficoll. Total RNA was extracted from freshly frozen cells using the RANiso Plus reagents, and was reversely transcribed to cDNA with Reverse Transcriptase M-MLV. Each cDNA then underwent analysis using TaqMan real-time quantitative PCR. Gene mutations in NRAS, DNMT3A and FLT3 were detected by PCR, and Transcripts of EVI1 in patient samples were quantified in triplicates using SYBR Green ΔΔCt method. The stably BCL11A expressing cells were obtained to explore the affects of BCLllA expressing in the survival and myeloid differentiation of Leukemic cell lines.6 kinds of BXH2 myeloid Leukemic cell lines were used to establish AML mouse models for the research of BCL11A expressing in Leukemic progression.Results:BCL11A aberrant expression is prevalent in AML and CML, mostly in FAB-MO and blast crisis of CML. Higher BCL11A expression is positively correlated with the presence of FLT3-ITD and DNMT3A-R882 mutations, and negatively with increased EVI1 expression levels. BCL11A overexpression in AML patients correlates with decreased overall survival, and can be an independent factor predicting adverse prognosis of patients with AML. BCL11A aberrant expression enhances cell survival and blocks myeloid differentiation. B114, B117 and B140 could be used to establish the mouse model of AML with different infiltration sites.Conclusions:In summary, our results have for the first time suggested the important role of BCL11A in the development and progression of human malignancies, supported that BCL11A primarily acts as an oncogene with potentially complex molecular interactions in leukemogenesis, and demonstrated that high expression levels of BCL11A is an independent indicator for worse prognosis, especially for the cytogenetically intermediate-risk patients with AML. We therefore propose that determination of BCL11A expression levels with quantitative real-time PCR be considered for the diagnosis and monitoring of AML and CML patients. This work has contributed to the understanding of BCL11A biology from a clinical perspective, and to the emergence of BCL11A as a valuable marker for the diagnosis, prognosis, and possibly, targeted therapy of leukemia. The AML mouse model established with BXH2 myeloid leukemic cell lines provides a way for the future exploration of BCL11A biology.