posted on 2016-02-16, 00:00authored bySuresh Vatakuti, Jeroen
L. A. Pennings, Emilia Gore, Peter Olinga, Geny M. M. Groothuis
Human
toxicity screening is an important stage in the development
of safe drug candidates. Hepatotoxicity is one of the major reasons
for the withdrawal of drugs from the market because the liver is the
major organ involved in drug metabolism, and it can generate toxic
metabolites. There is a need to screen molecules for drug-induced
hepatotoxicity in humans at an earlier stage. Transcriptomics is a
technique widely used to screen molecules for toxicity and to unravel
toxicity mechanisms. To date, the majority of such studies were performed
using animals or animal cells, with concomitant difficulty in interpretation
due to species differences, or in human hepatoma cell lines or cultured
hepatocytes, suffering from the lack of physiological expression of
enzymes and transporters and lack of nonparenchymal cells. The aim
of this study was to classify known hepatotoxicants on their phenotype
of toxicity in humans using gene expression profiles ex vivo in human precision-cut liver slices (PCLS). Hepatotoxicants known
to induce either necrosis (n = 5) or cholestasis
(n = 5) were used at concentrations inducing low
(<30%) and medium (30–50%) cytotoxicity, based on ATP content.
Random forest and support vector machine algorithms were used to classify
hepatotoxicants using a leave-one-compound-out cross-validation method.
Optimized biomarker sets were compared to derive a consensus list
of markers. Classification correctly predicted the toxicity phenotype
with an accuracy of 70–80%. The classification is slightly
better for the low than for the medium cytotoxicity. The consensus
list of markers includes endoplasmic reticulum stress genes, such
as C2ORF30, DNAJB9, DNAJC12, SRP72, TMED7, and UBA5, and a sodium/bile
acid cotransporter (SLC10A7). This study shows that human PCLS are
a useful model to predict the phenotype of drug-induced hepatotoxicity.
Additional compounds should be included to confirm the consensus list
of markers, which could then be used to develop a biomarker PCR-array
for hepatotoxicity screening.