Received July 28, 2007
Accepted on January 17, 2008

BASIC RESEARCH

Small-Molecule CFTR Inhibitors Slow Cyst Growth in Polycystic Kidney Disease

Baoxue Yang ^*, Nitin D. Sonawane ^*, Dan Zhao ^*, Stefan Somlo , and A. S. Verkman ^*

*Departments of Medicine and Physiology, University of California, San Francisco, California; and Department of Internal Medicine, School of Medicine, Yale University, New Haven, Connecticut

	Abstract

Cyst expansion in polycystic kidney disease (PKD) involves progressive fluid accumulation, which is believed to require chloride transport by the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Herein is reported that small-molecule CFTR inhibitors of the thiazolidinone and glycine hydrazide classes slow cyst expansion in in vitro and in vivo models of PKD. More than 30 CFTR inhibitor analogs were screened in an MDCK cell model, and near-complete suppression of cyst growth was found by tetrazolo-CFTR_inh-172, a tetrazolo-derived thiazolidinone, and Ph-GlyH-101, a phenyl-derived glycine hydrazide, without an effect on cell proliferation. These compounds also inhibited cyst number and growth by >80% in an embryonic kidney cyst model involving 4-d organ culture of embryonic day 13.5 mouse kidneys in 8-Br-cAMP–containing medium. Subcutaneous delivery of tetrazolo-CFTR_inh-172 and Ph-GlyH-101 to neonatal, kidney-specific PKD1 knockout mice produced stable, therapeutic inhibitor concentrations of >3 µM in urine and kidney tissue. Treatment of mice for up to 7 d remarkably slowed kidney enlargement and cyst expansion and preserved renal function. These results implicate CFTR in renal cyst growth and suggest that CFTR inhibitors may hold therapeutic potential to reduce cyst growth in PKD.