The proposed studies will investigate the role of the Wnt/beta catenin dependent secretome in promoting Ewing sarcoma metastasis. This work is an extension of published and unpublished data from the Lawlor lab which demonstrate that tumor cell heterogeneity is induced in response to changes in the tumor microenvironment (TME) and that the inherent plasticity of Ewing sarcoma cells permits rapid and reversible transitions between non-migratory and more migratory and invasive cell states. Our preliminary data now show that the secretome of Wnt/beta-catenin activated cells is altered in a manner that is likely to promote angiogenesis and osteolysis in the surrounding TME through crosstalk between tumor cells and the surrounding stroma. Importantly, preliminary data implicate canonical Wnt and TGF-beta pathways from the surrounding stroma in this crosstalk.
There are no mouse genetic models of Ewing sarcoma, making studies of a genetically engineered tumor microenvironment impossible in the absence of backcrosses to immune deficient backgrounds. We aim to create local mouse bone microenvironments (vossicles and ossicles; Pettway and McCauley, Methods Mol Biol. 2008;455:101-10) that can be implanted along with human Ewing tumor cells into the flanks of immune deficient NSG recipient mice. Vossicles will be harvested from wild-type as well at Wnt and TGF-beta-pathway mutant neonates, permitting direct evaluation of the contribution of signals from the local bone TME to Ewing sarcoma growth, angiogenesis and bone formation/resorption.