1 research outputs found
Comparative Proteomic Analysis of Human Liver Tissue and Isolated Hepatocytes with a Focus on Proteins Determining Drug Exposure
Freshly isolated human hepatocytes
are considered the gold standard
for in vitro studies of liver functions, including drug transport,
metabolism, and toxicity. For accurate predictions of the in vivo
outcome, the isolated hepatocytes should reflect the phenotype of
their in vivo counterpart, i.e., hepatocytes in human liver tissue.
Here, we quantified and compared the membrane proteomes of freshly
isolated hepatocytes and human liver tissue using a label-free shotgun
proteomics approach. A total of 5144 unique proteins were identified,
spanning over 6 orders of magnitude in abundance. There was a good
global correlation in protein abundance. However, the expression of
many plasma membrane proteins was lower in the isolated hepatocytes
than in the liver tissue. This included transport proteins that determine
hepatocyte exposure to many drugs and endogenous compounds. Pathway
analysis of the differentially expressed proteins confirmed that hepatocytes
are exposed to oxidative stress during isolation and suggested that
plasma membrane proteins were degraded via the protein ubiquitination
pathway. Finally, using pitavastatin as an example, we show how protein
quantifications can improve in vitro predictions of in vivo liver
clearance. We tentatively conclude that our data set will be a useful
resource for improved hepatocyte predictions of the in vivo outcome