Abstract 944: Loss of Ripk3 signaling promotes T cell lymphoma development in Tet2 deficient mice
Authors: Joshi Kanak , Zinzuwadia Shuchi , Mack Ryan , Zhang Lei , Liu Shanhui , Sellin Mark , Wei Wei , Breslin Peter , Kini Ameet R. , Zhang Jiwang 
Published: June 2022

Abstract
The TET2 gene is commonly mutated in multiple hematological malignancies and is frequently associated with poor prognosis. TET2 mutations are also found to occur in healthy individuals with no apparent hematological disease. A common factor observed between such individuals and those with the disease is the presence of increased inflammation and cytokine signature. A key mediator of inflammation and cytokine-induced necroptosis and metabolic signaling is the receptor-interacting protein kinase 3 (Ripk3). Ripk3 plays important tumor-promoting and suppressive roles in multiple cancers. Compared to bone marrow (BM) cells isolated from wild-type mice, higher levels of Ripk3 activity can be detected in Tet2-/- BM cells. Based on the evidence that Tet2 mutations alone are insufficient and are known to cooperate with other mutations for full-blown malignant transformation, we hypothesize that loss of Ripk3 signaling might promote the transformation of Tet2 mutant HSPCs To test our hypothesis we crossed Tet2 conditional knockout (Tet2fx/fx Mx1-Cre+) mice with Ripk3-/- mice to generate Tet2 and Ripk3 compound knockout (Tet2-/-Ripk3-/-) mice. We performed in vitro colony assays and in vivo engraftment and reconstitution assays on Bone marrow mononuclear cells (BM-MNC) derived from Tet2-/-Ripk3-/- and Tet2-/- mice. Our results indicate that TNF-α stimulation confers a significant hematopoietic advantage to Tet2-/- HSPCs which is abolished upon loss of Ripk3. Moreover, while Tet2-/- BM-MNC has significantly higher reconstitution ability in vivo, the additional loss of Ripk3 led to reduced engraftment and reconstitution that was comparable to WT BM-MNC. Given that TNF-α stimulation promotes Ripk3 activation, our results indicate that the TNF-RIPK3 signaling axis is essential in conferring enhanced hematopoietic fitness of Tet2-/- HSPCs.Tet2-/-Ripk3-/- mice developed aggressive tumors by 12-15 months of age as characterized by profound hepatosplenomegaly and lymphadenopathy, with substantial lymphocytosis, neutrophilia, anemia, and thrombocytopenia. There was extensive infiltration of tumor cells in the liver and spleen in diseased Tet2-/-Ripk3-/- mice. There was a marked expansion of both CD4+PD1+CXCR5+ follicular T helper cells (Tfh) and CD4+PD1+ peripheral T helper cells (Tph), indicating the development of a T cell lymphoma in the Tet2-/-Ripk3-/- mice. Additionally, disease characteristics including the reduced surface expression of CD3 in the tumor cells, increased levels of classical Th cytokines in the serum, as well as the presence of heterogeneous populations of cells within the tumor tissues recapitulate the pathological features of angioimmunoblastic T cell lymphoma (AITL). We are currently investigating Ripk3 signaling in the tumor cells of AITL patients and whether we can treat such aggressive fatal diseases by reactivating Ripk3 signaling.
Citation Format: Kanak Joshi, Shuchi Zinzuwadia, Ryan Mack, Lei Zhang, Shanhui Liu, Mark Sellin, Wei Wei, Peter Breslin, Ameet R. Kini, Jiwang Zhang. Loss of Ripk3 signaling promotes T cell lymphoma development in Tet2 deficient mice [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 944.