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.
Han
H K
HK
College of Pharmacy, The University of Michigan, Ann Arbor, Michigan 48109-1065, USA.
Rhie
J K
JK
Oh
D M
DM
Saito
G
G
Hsu
C P
CP
Stewart
B H
BH
Amidon
G L
GL
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