Pharmacogenomics of the cystic fibrosis transmembrane conductance regulator (CFTR) and the cystic fibrosis drug CPX using genome microarray analysis

Background: Cystic fibrosis (CF) is the most common lethal recessive diseas e affecting children in the U.S. and Europe. For this reason, a number of o ngoing attempts are being made to treat the disease either by gene therapy or pharmacotherapy. Several phase 1 gene therapy trials have been completed , and a phase 2 clinical trial with the xanthine drug CPX is in progress. T he protein coded by the principal CFTR mutation, Delta F508-CFTR, fails to traffic efficiently from the endoplasmic reticulum to the plasma membrane, and is the pathogenic basis for the missing cAMP-activated plasma membrane chloride channel. CPX acts by binding to the mutant Delta F508-CFTR and cor recting the trafficking deficit. CPX also activates mutant CFTR channels. T he comparative genomics of wild-type and mutant CFTR has not previously bee n studied. However, we have hypothesized that the gene expression patterns of human cells expressing mutant or wild-type CFTR might differ, and that a drug such as CPX might convert the mutant gene expression pattern into one more characteristic of wild-type CFTR. To the extent that this is true, a pharmacogenomic profile for such corrective drugs might be deduced that cou ld simplify the process of drug discovery for CF. Materials and Methods: To test this hypothesis we used cDNA microarrays to study global gene expression in human cells permanently transfected with ei ther wild-type or mutant CFTR. We also tested the effects of CPX on global gene expression when incubated with cells expressing either mutant or wild- type CFTR. Results: Wild-type and mutant Delta F508-CFTR induce distinct and different ial changes in cDNA microarrays, significantly affecting up to 5% of the to tal genes in the array. CPX also induces substantial mutation-dependent and -independent changes in gene expression. Some of these chances involve mov ement of gene expression in mutant cells in a direction resembling expressi on in wildtype cells. Conclusions: These data clearly demonstrate that cDNA array analysis of cys tic fibrosis cells can yield useful pharmacogenomic information with signif icant relevance to both gene and pharmacological therapy. We suggest that t his approach may provide a paradigm for genome-based surrogate endpoint tes ting of CF therapeutics prior to human administration.