In vitro-in silico analysis reveals that loss of tankyrase1/2 improves bile acid handling in genetically engineered HepG2 cultures.

Abstract

Modelling and simulation of hepatic bile acids (BA) kinetics is instrumental to understand mechanisms underlying drug-induced cholestasis (DiCho). A recent study has shown that the loss of tankyrase1/2 (TNKS1/2) matured the hepatic phenotype in vitro in terms of cellular respiration rate and metabolism. However, whether this phenotype was accompanied with more in vivo relevant hepatic BA handling was not investigated. The present study explored whether tankyrase1/2 loss improved hepatic BA handling through an integrated in vitro-in silico approach. To do so, double knockout (DKO) TNKS1/2 HepG2 cells were exposed to a 10 µM BA mixture containing chenodeoxycholic acid (CDCA), cholic acid, deoxycholic acid, and lithocholic acid. BA levels and their metabolites were subsequently quantified in medium and cell extracts using liquid chromatography-tandem mass spectrometry (LC-MSMS). The in vitro data were then used as input in an ordinary differentially equation (ODE)-based kinetics model that was solved in R, using CDCA and its metabolites as index. The analyses revealed that glycine and taurine conjugation were enhanced by 1.5- and 2.2-fold, respectively, in the HepG2-DKO cells compared to the control. Further, the mechanistic model unveiled that efflux of taurochenodeoxycholic acid was elevated. In conclusion, HepG2-DKO cells provide a robust foundation for building a sensitive in vitro model for DiCho studies. Furthermore, this study discovered that tankyrase1/2 loss improved BA metabolism and kinetics, promoting the utility of tankyrase1/2 inhibitors, like XAV-939, in future pre-clinical BA disposition interaction studies.