Abstract
Serotonin (5-HT) secreted from enterochromaffin cells (EC cells) stimulates the vomiting center via afferent neurotransmission, developing drug-induced nausea and vomiting. In this study, we aimed to construct in vitro assay system which can predict the risk of drug-induced nausea and vomiting by efficiently differentiating crypt-derived human jejunal stem cell spheroids into EC cells and evaluating their drug exposure-dependent 5-HT release.
Human jejunal spheroids supplemented with Notch inhibitor, DAPT, showed increased gene expression levels of EC cell markers, CHGA and TPH1, and the increase of 5-HT positive cell population was confirmed by immunostaining, suggesting that differentiation into EC cells was promoted. Next, forskolin stimulation was performed as a positive control for 5-HT release, and the amount of 5-HT release into the supernatant was quantified using LC-MS/MS. The amount of 5-HT release was greatly increased under the culture condition supplemented with DAPT, suggesting that the 5-HT release activity from EC cells can be evaluated in this system.
We confirmed the increase in 5-HT release by the exposure of drugs for which the clinical risk of nausea and vomiting was reported, such as cisplatin, crizotinib, and metformin in our assay system. We are currently investigating the usefulness of 5-HT release assessment as a surrogate marker of emesis by evaluating the relation between drug potency of accelerated 5-HT release and the incidence of nausea and vomiting in clinical situations. We are also exploring the mechanism of the regulation of 5-HT release from EC cells upon drug exposure by evaluating direct cytotoxicity to EC cells and functional changes.
