CHO/hPEPT1 cells overexpressing the human peptide transporter (hPEPT1) as an alternative in vitro model for peptidomimetic drugs.
The present study characterized Chinese hamster ovary cells overexpressing a human intestinal peptide transporter, CHO/hPEPT1 cells, as an in vitro model for peptidomimetic drugs. The kinetic parameters of Gly-Sar uptake were determined in three different cell culture systems such as untransfected CHO cells (CHO-K1), transfected CHO cells (CHO/hPEPT1) and Caco-2 cells. Vmax in CHO/hPEPT1 cells was approximately 3-fold higher than those in Caco-2 cells and CHO-K1 cells, while Km values were similar in all cases. The uptake of beta-lactam antibiotics in CHO/hPEPT1 cells was three to twelve fold higher than that in CHO-K1 cells, indicating that CHO/hPEPT1 cells significantly enhanced the peptide transport activity. However, amino acid drugs also exhibited high cellular uptake in both CHO-K1 and CHO/hPEPT1 cells due to the high background level of amino acid transporters. Thus, cellular uptake study in CHO/hPEPT1 cells is not sensitive enough to distinguish the peptidyl drugs from amino acid drugs. The potential of CHO/hPEPT1 cells as an in vitro model for peptidomimetic drugs was also examined through the inhibition study on Gly-Sar uptake. Peptidomimetic drugs such as beta-lactam antibiotics and enalapril significantly inhibited Gly-Sar uptake whereas the nonpeptidyl compounds, L-dopa and alpha-methyldopa, did not compete with Gly-Sar for cellular uptake within the therapeutic concentrations. In conclusion, the present study demonstrates the further characterization of CHO/hPEPT1 cells as an uptake model as well as inhibition study and suggests their utility as an alternative in vitro model for drug candidates targeting the hPEPT1 transporter.
College of Pharmacy, The University of Michigan, Ann Arbor, Michigan 48109-1065, USA.
H K
HK
Han
J K
JK
Rhie
D M
DM
Oh
G
G
Saito
C P
CP
Hsu
B H
BH
Stewart
G L
GL
Amidon
D000818:Animals; D001692:Biological Transport; D016466:CHO Cells / Q000378:metabolism*; D018938:Caco-2 Cells / Q000378:metabolism*; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D006224:Cricetinae; D004151:Dipeptides / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics*; D006801:Humans; D007700:Kinetics; D000074011:Peptide Transporter 1; D015203:Reproducibility of Results; D027981:Symporters; D014162:Transfection
D002352:Carrier Proteins; D004151:Dipeptides; D000074011:Peptide Transporter 1; C082186:SLC15A1 protein, human; D027981:Symporters; C004194:glycylsarcosine