Characterization of Hematopoietic Cancers Generated in a SB Mutagenesis Screen

Sleeping-Beauty transponson mutagenesis can identify genetic mutations associated with tumors that are a result of this forward genetic screen. However, challenges still exist between identifying these tumors and comparing them to tumors in humans. In a VE-Cadherin driven SB transposon mutagenesis screen, a cohort of mice suffering from hematopoietic malignancies was generated to model tumors found in humans. VE-Cadherin Cre is used because its first activated in hematopoietic stem cells that bud from hemogenic endothelium. Inducing mutagenesis at this moment allows for mutagenesis to be in HSC from various endothelial beds during mid-gestation. The major goal of this project is find the underlying genes of the hematopoietic malignancies (HM) that were generated.  The HMs were analyzed by several methods including blood/bone marrow cytospin, hematoxylin & eosin (H&E) and specific esterase (Leder) staining of compromised organs, and immunohistochistry using various hematopoietic cell markers. Preliminary data suggests that proliferating cells came from the thymus or spleen and invaded other non-hematopoietic organs. Additionally, some cells were identified as differentiated leukocytes (immune cells), while others are assumed to be undifferentiated (immature progenitor) due to no expression of specific markers used in immunohistochemisty.  From sequencing the thymus and spleens at transposon genome junctions, the results suggest that the enlarge spleen phenotype is myeloid while the enlarged thymus phenotype is lymphoid. This work is significant by further confirming that hemogenic endothelium is a source of hematopoesis. Furthermore, using the SB mutagenesis screen for hematopoietic linage allowed the generation and identification of both lymphoid and myloid malignancies.