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 ‘weight of evidence’ cancer risk assessment for xenobiotic-induced rodent liver tumors

Pharmacological characterization of a novel 5-hydroxybenzothiazolone-derived b2-adrenoceptor agonist with functional selectivity for anabolic effects on skeletal muscle resulting in a wider cardiovascular safety window in preclinical studies

Copyright ª 2019 by The Author(s) The anabolic effects of b2-adrenoceptor (b2-AR) agonists on skeletal muscle have been demonstrated in various species. However, the clinical use of b2-AR agonists for skeletal muscle wasting conditions has been limited by their undesired cardiovascular effects. Here, we describe the preclinical pharmacological profile of a novel 5-hydroxybenzothiazolone (5-HOB) derived b2-AR agonist in comparison with formoterol as a representative b2-AR agonist that have been well characterized. In vitro, 5-HOB has nanomolar affinity for the human b2-AR and selectivity over the b1-AR and b3-AR. 5-HOB also shows potent agonistic activity at the b2-AR in primary skeletal muscle myotubes and induces hypertrophy of skeletal muscle myotubes. Compared with formoterol, 5-HOB demonstrates comparable full-agonist activity on cAMP production in skeletal muscle cells and skeletal muscle tissue–derived membranes. In contrast, a greatly reduced intrinsic activity was determined in cardiomyocytes and cell membranes prepared from the rat heart. In addition, 5-HOB shows weak effects on chronotropy, inotropy, and vascular relaxation compared with formoterol. In vivo, 5-HOB significantly increases hind limb muscle weight in rats with attenuated effects on heart weight and ejection fraction, unlike formoterol. Furthermore, changes in cardiovascular parameters after bolus subcutaneous treatment in rats and rhesus monkeys are significantly lower with 5-HOB compared with formoterol. In conclusion, the pharmacological profile of 5-HOB indicates superior tissue selectivity compared with the conventional b2-AR agonist formoterol in preclinical studies and supports the notion that such tissue-selective agonists should be investigated for the safe treatment of muscle-wasting conditions without cardiovascular limiting effects