Integrative analysis reveals aged clonal B cells, microenvironment and c-Myc activation in the origin of age-related lymphoma

AbstractWhile cancer is an age-related disease, most studies focus on genetically engineered younger mouse models. Here, we uncover how cancer develops as a consequence of the naturally aged immune system in mice. B-cell lymphoma frequently occurs in aged mice and is associated with increased cell size, splenomegaly, and a novel clonal B-cell population. Age-emergent B cells clonally expand outside of germinal centers driven by somatic mutations, activated c-Myc and hypermethylated promoters, and both genetically and epigenetically recapitulate human follicular and diffuse-large B-cell lymphomas. Mechanistically, mouse cancerous B cells originate from age-associated B cells, which are atypical memory B cells. Age-associated B cells secrete a spectrum of proinflammatory cytokines and activate paracrinally the expression of c-Myc in surrounding B cells. Although clonal B cells are a product of an aging microenvironment, they evolve being self-sufficient and support malignancy when transferred into young mice. Inhibition of mTOR and c-Myc attenuates premalignant changes in B cells during aging and emerges as a therapeutic strategy to delay the onset of age-related lymphoma. Together, we uncover how aging generates cancerous B cells, characterize a model that captures the origin of spontaneous cancer during aging and identify interventions that may postpone age-associated lymphoma.