3 research outputs found
Xenobiotic CAR activators induce Dlk1-Dio3 locus non-coding RNA expression in mouse liver
Predicting the impact of human exposure to chemicals such as pharmaceuticals and
agrochemicals requires the development of reliable and predictive biomarkers
suitable for the detection of early events potentially leading to adverse outcomes. In
particular, drug-induced non-genotoxic carcinogenesis (NGC) during preclinical
development of novel therapeutics intended for chronic administration in humans is a
major challenge for drug safety.
We previously demonstrated Constitutive Androstane Receptor (CAR) and WNT
signaling-dependent up-regulation of the pluripotency associated Dlk1-Dio3 imprinted
gene cluster non-coding RNAs (ncRNAs) in the liver of mice treated with tumorpromoting
doses of phenobarbital (PB). Here, to explore the sensitivity and the
specificity of this candidate liver tumor promotion ncRNAs signature we compared
phenotypic, transcriptional and proteomic data from wild-type, CAR/PXR double
knock-out and CAR/PXR double humanized animals treated with tumor-promoting
doses of PB or chlordane, both well-established CAR activators. We further
investigated selected transcriptional profiles from mouse liver samples exposed to
seven NGC compounds working through different mode of actions, overall
suggesting CAR-activation specificity of the Dlk1-Dio3 long ncRNAs activation. We
propose that Dlk1-Dio3 long ncRNAs up-regulation is an early CAR-activation
dependent transcriptional signature during xenobiotic-induced mouse liver tumor
promotion. This signature may further contribute mode of action-based âweight of
evidenceâ cancer risk assessment for xenobiotic-induced rodent liver tumors
Efficient differentiation of hepatocytes from human embryonic stem cells exhibiting markers recapitulating liver development in vivo
The potential to differentiate human embryonic stem cells (hESCs) in vitro to provide an unlimited source of human hepatocytes for use in biomedical research, drug discovery, and the treatment of liver diseases holds great promise. Here we describe a three-stage process for the efficient and reproducible differentiation of hESCs to hepatocytes by priming hESCs towards definitive endoderm with activin A and sodium butyrate prior to further differentiation to hepatocytes with dimethyl sulfoxide, followed by maturation with hepatocyte growth factor and oncostatin M. We have demonstrated that differentiation of hESCs in this process recapitulates liver development in vivo: following initial differentiation, hESCs transiently express characteristic markers of the primitive streak mesendoderm before turning to the markers of the definitive endoderm; with further differentiation, expression of hepatocyte progenitor cell markers and mature hepatocyte markers emerged sequentially. Furthermore, we have provided evidence that the hESC-derived hepatocytes are able to carry out a range of hepatocyte functions: storage of glycogen, and generation and secretion of plasma proteins. More importantly, the hESC-derived hepatocytes express several members of cytochrome P450 isozymes, and these P450 isozymes are capable of converting the substrates to metabolites and respond to the chemical stimulation. Our results have provided evidence that hESCs can be differentiated efficiently in vitro to functional hepatocytes, which may be useful as an in vitro system for toxicity screening in drug discovery.</p