RESUMEN
Inflammation promotes solid tumor progression, but how regulatory mechanisms of inflammation may impact leukemia is less well studied. Using annexin A5 (ANXA 5), a calcium-binding protein known for apoptosis, which we discovered to be differentially expressed in the bone marrow microenvironment (BMM) of mice with acute myeloid (AML) versus chronic myeloid leukemia, as a model system, we unravel here a circuit in which AML-derived tumor necrosis factor (TNF)α dose-dependently reduces ANXA5 in the BMM. This creates an inflammatory BMM via elevated levels of prostaglandin E2 (PGE2). Via binding to its EP4 receptor, PGE2 increases ï¢-catenin and hypoxia-inducible factor (HIF) 1 α signaling in AML cells, thereby accelerating PGE2-sensitive AML. Human trephine biopsies may show lower ANXA5 expression and higher PGE2 expression in AML compared to other hematological malignancies. Further, syngeneic and xenogeneic transplantation models suggest a survival benefit after treatment with the inhibitor of prostaglandin-endoperoxide synthase 2 (cyclooxygenase 2 (COX2)), celecoxib, plus cytarabine in those AML types highly sensitive to PGE2 compared to cytarabine alone. Taken together, TNFα/ANXA5/NF-kB/COX2/PGE2-mediated inflammation influences AML course in a highly differential and circular manner, and AML patients with 'inflammatory AML' may benefit from antiphlogistic agents as adjunct therapy.