Abstract B34: Cord blood CD34+ HSPCs: An in vitro model system for characterizing NUP98 fusions

Abstract

Abstract Chromosomal translocations of the Nucleoporin 98 gene (NUP98) are associated with multiple hematopoietic malignancies. In particular, NUP98 rearrangements can be found in up to 6.6% of de novo cases of pediatric AML. Specific subpopulations of pediatric AML appear to be even more enriched for NUP98 fusions, with over 16% of cytogenetically normal pediatric AML patients and 15% of non-Down syndrome acute megakaryoblastic leukemia (AMKL) patients harboring these fusions. Clinically, the NUP98-KDM5A fusion is associated with erythroid and megakaryocytic leukemias while the NUP98-NSD1 fusion is associated with myelomonocytic leukemias. When NUP98 fusions are present in AML, they confer a poor prognosis. To better characterize the role of these fusions in human hematopoiesis, we used cord blood CD34+ (cb-CD34+) hematopoietic stem and progenitor cells (HSPCs) as an in vitro model system. We transduced cb-CD34+ HSPCs with NUP98-NSD1, NUP98-KDM5A, or empty vector control and studied the effects on cell proliferation and differentiation in liquid culture media containing cytokines (IL-6, FLT3-Ligand, SCF, TPO, and SR1 (an aryl hydrocarbon receptor antagonist)). NUP98-NSD1 and NUP98-KDM5A fusions increase the proliferation rate in liquid culture by three-fold and 19-fold, respectively (p<0.05). Consistent with observations from patients with these fusions, cells expressing NUP98-KDM5A have increased expression of CD235A and CD71, consistent with erythroid differentiation (p<0.05). In addition, cells expressing NUP98-NSD1 have increased expression of CD11b compared to NUP98-KDM5A (p<0.01) expressing cells. When placed in methylcellulose, the NUP98 fusions tested had no effect on total colony number, but we observed more erythroid differentiation for NUP98-KDM5A compared to vector control (p<0.05). Overall, the results of these in vitro studies demonstrate increased proliferation and inhibition of differentiation in HSPCs by NUP98 fusions, and cell differentiation patterns parallel the different AML subtypes observed in patients with NUP98-NSD1 and NUP98-KDM5A fusions. We propose cbCD34+ HSPCs as a promising system for in vitro modeling of NUP98 fusions. Citation Format: Ryan Hiltenbrand, Jonathan Miller, Jeffery Klco. Cord blood CD34+ HSPCs: An in vitro model system for characterizing NUP98 fusions [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B34.