ERBB receptor activation is required for profibrotic responses to transforming growth factor beta.

Engagement of the transforming growth factor-β (TGF-β) receptor complex activates multiple signaling pathways that play crucial roles in both health and disease. TGF-β is a key regulator of fibrogenesis and cancer-associated desmoplasia; however, its exact mode of action in these pathologic processes has remained poorly defined. Here, we report a novel mechanism whereby signaling via members of the ERBB or epidermal growth factor family of receptors serves as a central requirement for the biological responses of fibroblasts to TGF-β. We show that TGF-β triggers upregulation of ERBB ligands and activation of cognate receptors via the canonical SMAD pathway in fibroblasts. Interestingly, activation of ERBB is commonly observed in a subset of fibroblast but not epithelial cells from different species, indicating cell type specificity. Moreover, using genetic and pharmacologic approaches, we show that ERBB activation by TGF-β is essential for the induction of fibroblast cell morphologic transformation and anchorage-independent growth. Together, these results uncover important aspects of TGF-β signaling that highlight the role of ERBB ligands/receptors as critical mediators in fibroblast responses to this pleiotropic cytokine.