Cell competition between wild-type and JAK2V617F mutant cells in a murine model of a myeloproliferative neoplasm

The myeloproliferative neoplasms (MPNs) are clonal stem cell disorders characterized by overproduction of mature blood cells and increased risk of transformation to frank leukemia. The acquired kinase mutation JAK2V617F plays a central role in a majority of these disorders. The hematopoietic stem cell (HSC) compartment in MPN is heterogeneous with the presence of both JAK2 wild-type and JAK2V617F mutant cells in most patients with MPN. Utilizing in vitro co-culture assays and in vivo competitive transplantation assays, we found that the presence of wild-type cells altered the behavior of co-existing JAK2V617F mutant cells, and a mutant microenvironment (niche) could overcome the competition between wild-type and mutant cells, leading to mutant clonal expansion and overt MPN. We also demonstrated that competition between wild-type and JAK2V617F mutant cells triggered a significant immune response, and there was a dynamic PD-L1 deregulation in the mutant stem/progenitor cells caused by their interactions with the neighboring wild-type cells and the microenvironment. Therefore, while accumulation of oncogenic mutations is unavoidable during aging, our data suggest that, if we could therapeutically enhance normal cells ability to compete, we might be better able to control neoplastic cell expansion and prevent the development of a full-blown malignancy. Key PointsO_LIThe presence of wild-type cells alters the behavior of co-existing JAK2V617F mutant cells C_LIO_LIA mutant microenvironment overcomes the competition between wild-type and JAK2V617F mutant cells, leading to the development of a MPN C_LI