Abstract LB559: The X-linked gene for the helicase DDX3X is required for lymphoid differentiation and MYC-driven lymphomagenesis

Abstract

Abstract The X-linked gene DDX3X encodes an RNA helicase and is mutated at high frequencies in several types of human B-cell lymphoma. Females have two active DDX3X alleles and males carry a DDX3Y homolog on the Y chromosome. We show here that pan-hematopoietic, homozygous deletion of Ddx3x in female mice perturbs erythropoiesis causing early developmental arrest. However, both hemizygous male and heterozygous female embryos develop normally, suggesting that one Ddx3x allele is sufficient for fetal hematopoietic development in females and that the Ddx3y allele can compensate for the loss of Ddx3x in males. In adult mice, loss of DDX3X affects hematopoietic progenitors, early lymphoid development, marginal zone, and germinal center B-cells as well as lymphomagenesis driven by an Eμ-Myc or λ-Myc transgene in a sex-dependent manner. A B-cell-specific depletion of both Ddx3x alleles induces a delay in tumorigenesis in female mice while Ddx3x deletion in male mice does not impact tumorigenesis. However, male Eμ-Myc mice lacking Ddx3x on a pan-hematopoietic way remained for the majority lymphoma-free. The few tumors that appeared in these male mice showed upregulated expression of DDX3Y indicating a requirement of DDX3 activity for lymphomagenesis. Our data reveal sex-specific roles of DDX3X in erythro- and lymphopoiesis as well as in MYC-driven lymphomagenesis, which are important when considering inhibition of DDX3 as a treatment of Myc dependent B-cell lymphoma. Citation Format: Marion Lacroix, Hugues Beauchemin, Julie Ross, Jennifer Fraszczak, Peiman Shooshtarizadeh, Riyan Chen, Tarik Moroy. The X-linked gene for the helicase DDX3X is required for lymphoid differentiation and MYC-driven lymphomagenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB559.