Organic anion-transporting polypeptide (OATP)1B1, OATP1B3, and OATP2B1 transporters play an important role in hepatic drug disposition. Recently, an increasing number of studies have reported proteomic expression data for OATP transporters. However, systematic analysis and understanding of the actual differences in OATP expression between liver tissue and commonly used cellular systems is lacking. In the current study, meta-analysis was performed to assess the protein expression of OATP transporters reported in hepatocytes relative to liver tissue and to identify any potential correlations in transporter expression levels in the same individual. OATP1B1 was identified as the most abundant uptake transporter at 5.9 6 8.3, 5.8 6 3.3, and 4.2 6 1.7 fmol/mg protein in liver tissue, sandwich-cultured human hepatocytes (SCHH), and cryopreserved suspended hepatocytes, respectively. The rank order in average expression in liver tissue and cellular systems was OATP1B1 > OATP1B3 OATP2B1. Abundance levels of the OATP transporters investigated were not significantly different between liver and cellular systems, with the exception of OATP2B1 expression in SCHH relative to liver tissue. Analysis of OATP1B1, OATP1B3, and OATP2B1 liver expression data in the same individuals (n = 86) identified weak (OATP1B1-OATP2B1) to moderately (OATP1B3-OATP2B1) significant correlations. A significant weak correlation was noted between OATP1B1 abundance and age of human donors, whereas expression of the OATPs investigated was independent of sex. Implications of the current analysis on the in vitroin vivo extrapolation of transporter-mediated drug disposition using physiologically based pharmacokinetic models are discussed.

Health and Environmental Sciences Institute (HESI) (https://hesiglobal.org). HESI is a publicly supported, tax-exempt organization that provides an international forum to advance the understanding of scientific issues related to human health, toxicology, risk assessment, and the environment through the engagement of scientists from academia, government, industry, nongovernmental organizations, and other strategic partners. This HESI scientific initiative is primarily supported by in-kind contributions from public and private sector participants of time, expertise, and experimental effort. These contributions are supplemented by direct funding that largely supports program infrastructure and management that was provided by HESI's corporate sponsors.