Use of Kinase Inhibitors to Correct ΔF508-CFTR Function

The most common mutation in cystic fibrosis (CF) is a deletion of Phe at position 508 (Delta F508-CFTR). Delta F508-CFTR is a trafficking mutant that is retained in the ER, unable to reach the plasma membrane. To identify compounds and drugs that rescue this trafficking defect, we screened a kinase inhibitor library enriched for small molecules already in the clinic or in clinical trials for the treatment of cancer and inflammation, using our recently developed high-content screen technology (Trzcinska-Daneluti et al. Mol. Cell. Proteomics 8: 780, 2009). The top hits of the screen were further validated by (1) biochemical analysis to demonstrate the presence of mature (Band C) Delta F508-CFTR, (2) flow cytometry to reveal the presence of Delta F508-CFTR at the cell surface, (3) short-circuit current (Isc) analysis in Ussing chambers to show restoration of function of the rescued Delta F508-CFTR in epithelial MDCK cells stably expressing this mutant (including EC50 determinations), and importantly (4) Isc analysis of Human Bronchial Epithelial (HBE) cells harvested from homozygote Delta F508-CFTR transplant patients. Interestingly, several inhibitors of receptor Tyr kinases (RTKs), such as SU5402 and SU6668 (which target FGFRs, VEGFR, and PDGFR) exhibited strong rescue of Delta F508-CFTR, as did several inhibitors of the Ras/Raf/MEK/ERK or p38 pathways (e. g. (5Z)-7-oxozeaenol). Prominent rescue was also observed by inhibitors of GSK-3 beta (e. g. GSK-3 beta Inhibitor II and Kenpaullone). These results identify several kinase inhibitors that can rescue Delta F508-CFTR to various degrees, and suggest that use of compounds or drugs already in the clinic or in clinical trials for other diseases can expedite delivery of treatment for CF patients. Molecular & Cellular Proteomics 11: 10.1074/mcp.M111.016626, 745-757, 2012.