Characterizing the role of ETV6 in lymphoid development and B-cell acute lymphoblastic leukemia predisposition

Abstract

B cell acute lymphoblastic leukemia (ALL) is the most common form of pediatric cancer and one of the leading causes of death in children, characterized by clonal expansion of malignant lymphoid progenitors. While recent studies have identified a number of genetic risk factors for the development of ALL, our understanding of the mechanism of susceptibility to the disease remains incomplete. Sequencing studies have implicated germline ETV6 mutations to predispose patients to development of blood cancers and particularly to B-cell ALL. However, the specific role for ETV6 has not been characterized. Here, I investigated the role of germline ETV6 mutations in human B cell lymphopoiesis and predisposition to ALL. Human cord blood-derived and adult peripherally mobilized CD34+ cells were edited using a CRISPR-Cas9 editing strategy that has been established in our laboratory. I established an optimized in vitro co-culture system for B cell differentiation from hematopoietic stem cells. I examined the effects of this knockdown on cellular differentiation, including flow cytometry for phenotypic analysis of different stages of B cell lymphopoiesis. Perturbation of ETV6, particularly in the ETS domain, in CD34+ HSPCs produced an altered lymphoid progenitor pool, notably a reduction in CD45RA+CD33-- and a subtle increase in CD19+-expressing cells at one week of differentiation. Understanding the role of germline ETV6 variation offers unique insight into the molecular etiology of and predisposition to ALL, providing future opportunities for treatment and potential prevention.