The HepaRG cell line is a highly differentiated human
hepatoma cell line, displaying the expression of various drug transporters. However, functional expression of
nucleoside transporters remains poorly characterized in HepaRG cells, although these transporters play a key role in hepatic uptake of
antiviral and anticancer drugs. The present study was, therefore, designed to characterize the expression, activity and regulation of equilibrative (ENT) and concentrative (CNT)
nucleoside transporter isoforms in differentiated HepaRG cells. These cells were found to exhibit a profile of
nucleoside transporter mRNAs similar to that found in human hepatocytes, i.e., notable expression of ENT1, ENT2 and CNT1, with very low or no expression of CNT2 and CNT3. ENT1 activity was, next, demonstrated to be the main
uridine transport activity present in HepaRG cells, like in cultured human hepatocytes. Various physiological factors, such as
protein kinase C (PKC) activation or treatment by inflammatory
cytokines or
hepatocyte growth factor (HGF), were additionally found to regulate expression of ENT1, ENT2 and CNT1; PKC activation and HGF notably concomitantly induced
mRNA expression and activity of ENT1 in HepaRG cells. Overall, these data suggest that HepaRG cells may be useful for analyzing cellular pharmacokinetics of
nucleoside-like drugs in human hepatic cells, especially of those handled by ENT1.