Epithelial-to-mesenchymal transition (EMT) plays a role in chronic obstructive pulmonary diseases (COPD). Cyclic adenosine monophosphate (cAMP) can inhibit transforming growth factor-β1 (TGF-β1) mediated EMT. Although compartmentalization via A-kinase anchoring proteins (AKAPs) is central to cAMP signaling, functional studies on their therapeutic value in the lung EMT process are lacking. Bronchial epithelial (BEAS-2B, primary HAE cells) were exposed to TGF-β1. Epithelial (E-cadherin, ZO-1) and mesenchymal markers collagen Ӏ (mRNA, protein) were analyzed. St-Ht31 disrupted AKAP-PKA interactions. TGF-β1 release was measured by ELISA. TGF-β1-sensitive AKAPs Ezrin, AKAP95 and Yotiao were silenced using siRNA. Cell migration was analyzed by wound healing assay, xCELLigence, Incucyte. Prior to TGF-β1, dibutyryl-cAMP (dbcAMP), fenoterol, rolipram, cilostamide, forskolin were used to elevate intracellular cAMP. TGF-β1 induced morphological changes, decreased E-cadherin but increased collagen Ӏ and cell migration, a process reversed by PF-670462. TGF-β1 altered (mRNA, protein) expression of Ezrin, AKAP95 and Yotiao. St-Ht31 decreased E-cadherin (mRNA, protein), but counteracted TGF-β1-induced collagen Ӏ upregulation. Cigarette smoke (CS) increased TGF-β1 release, activated TGF signaling, augmented cell migration and reduced E-cadherin expression, a process blocked by TGF-β1 neutralizing antibody. Silencing of Ezrin, AKAP95 and Yotiao diminished TGF-β1-induced collagen Ӏ expression, as well as TGF-β1-induced cell migration. Fenoterol, rolipram, and cilostamide, in AKAP silenced cells pointed to distinct cAMP compartments. We conclude that Ezrin, AKAP95 and Yotiao promote TGF-β1-mediated EMT, linked to a TGF-β1 release by CS. AKAP members define the ability of fenoterol, rolipram and cilostamide to modulate the EMT process, and are potential relevant targets in the treatment of COPD.
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