The chromatin remodeling BAP complex limits tumor promoting activity of the Hippo pathway effector Yki to prevent neoplastic transformation in Drosophila epithelia

Abstract

SWI/SNF chromatin remodeling complexes are mutated in many human cancers. In this report we make use of a Drosophila genetic model for epithelial tumor formation to explore the tumor suppressive role of SWI/SNF complex proteins. Members of the BAP complex exhibit tumor suppressor activity in tissue overexpressing the Yorkie (Yki) proto-oncogene, but not in tissue overexpressing EGFR. The BAP complex has been reported to serve as a Yki-binding cofactor to support Yki target expression. However, we observed that depletion of BAP leads to ectopic expression of Yki targets both autonomously and non-autonomously, suggesting additional indirect effects. We provide evidence that BAP complex depletion causes upregulation of the Wingless and Dpp morphogens to promote tumor formation in cooperation with Yki.