Inhibiting focal adhesion kinase ameliorates cyst development in polycystin-1-deficient polycystic kidney disease in animal model

Abstract

Background Autosomal dominant polycystic kidney disease (ADPKD) is characterized by numerous cysts originatingfromrenal tubulesandisassociatedwithsignificant tubularepithelial cell proliferation.Focal adhesion kinase (FAK) promotes tumor growth by regulating multiple proliferative pathways. Methods We established the forskolin (FSK)-induced three-dimensional (3D) Madin-Darby Canine Kidney cystogenesis model and 8-bromoadenosine-3',5'-cyclic monophosphate-stimulated cyst formation in ex vivo embryonic kidney culture. Cultured human renal cyst-lining cells (OX-161) and normal tubular epithelial cellswere treatedwith FAKinhibitors or transfectedwith green fluorescent protein-taggedFAKmutantplasmids for proliferation study. Furthermore, we examined the role of FAK in two transgenic ADPKD animal models, the kidney-specific Pkd1 knockout and the collecting duct-specific Pkd1 knockout mouse models. Results FAK activity was significantly elevated in OX-161 cells and in two ADPKD mouse models. Inhibiting FAK activity reduced cell proliferation inOX-161 cells and prevented cyst growth in ex vivo and 3Dcystmodels. In tissue-specific Pkd1 knockoutmousemodels, FAKinhibitors retarded cyst development andmitigated renal function decline. Mechanically, FSK stimulated FAK activation in tubular epithelial cells, which was blocked by a protein kinase A (PKA) inhibitor. Inhibition of FAK activation by inhibitors or transfected cells with mutant FAK constructs interrupted FSK-mediated Src activation and upregulation of ERK and mTOR pathways. Conclusions Our study demonstrates the critical involvement of FAK in renal cyst development, suggests that FAK is a potential therapeutic target in treating patients with ADPKD, and highlights the role of FAK in cAMP-PKA-regulated proliferation.