Altered sulfate transport via anion exchange in CFPAC is corrected by retrovirus-mediated CFTR gene transfer

PANC-1 (a permanent epithelioid cell line initiated from a pancreatic carcinoma of ductal origin) and CFPAC (a ductal epithelioid cell line established from a cystic fibrosis patient with pancreatic adenocarcinoma) display sulfate transport via carrier-mediated anion exchange as supported by the following lines of evidence: 1) saturation kinetics, 2) inhibition by the anion exchange inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), and 3) substrate specificity. The DIDS-sensitive component of sulfate uptake is markedly inhibited by S2O3(2-) and MoO4(2-) but not by HAsO4(2-), H2PO4-, or gluconate-. Competitive inhibition of SO4(2-) uptake by extracellular Cl- (Cl-o) and stimulation of SO4(2-) efflux by Cl-o support the possibility that SO4(2-) transport occurs via a SO4(2-)-Cl- exchange mechanism. Inhibition of sulfate uptake and stimulation of sulfate efflux by extracellular HCO3- indicate that SO4(2-)-HCO3- exchange is an alternative mechanism for sulfate transport in these cells. Further support for SO4(2-) being transported via a typical anion exchanger is the stimulation of its uptake at low extracellular pH and high intracellular pH. Amphotropic viruses have been used by others (M. L. Drumm, H. A. Pope, W. H. Cliff, J. M. Rommens, S. A. Marvin, L.-C. Tsui, F. S. Collins, R. A. Frizzell, and J. M. Wilson. Cell 62: 1227-1233, 1990) to transduce a functional cystic fibrosis transmembrane regulator (CFTR) cDNA into CFPAC, resulting in the PLJ-CFTR clones. Control clones (PLJ) were obtained by exposing CFPAC cells to control virus. In the present study, we report a striking 10-fold increase in the capacity of the DIDS-sensitive component of the sulfate transporter in two PLJ-CFTR clones (which had been shown by others to express corrected Cl- channel activity) compared with CFPAC and two PLJ clones. Our findings indicate that expression of the CFTR gene from a retroviral vector, which confers normal Cl- channel activity in the PLJ-CFTR pancreas epithelial clones, is capable of correcting a second aspect of the cystic fibrosis phenotype, altered sulfate transport via an anion exchange mechanism.