YAP disrupts bile acid homeostasis to drive cancer-associated cachexia [Crispant_RNAseq]

Cancer-associated cachexia is a severe metabolic syndrome marked by dramatic loss of adipose and muscle mass. Although preclinical models have advanced our understanding of cachexia, there are still no approved therapies due to the limited insights into the mechanisms underlying tissue wasting. Here, we utilise a YAP-driven model of liver cancer in zebrafish, which rapidly develops cachexia, to uncover an evolutionarily conserved role for bile acid disruption in the onset of cachexia. Spatial transcriptomic analysis revealed that YAP induces a bi-lineage cholangiocarcinoma phenotype, which was associated with bile acid dysregulation. Mechanistically, we establish that both bile acid synthesis (via CYP7A1) and signalling through the bile acid receptor TGR5 are essential for cachexia induction. Notably, we find that the promotion of bile acid excretion with odevixibat ameliorates cachexia. Together, our findings reveal an evolutionarily conserved mechanism by which YAP promotes cachexia and suggest a potential therapeutic strategy to treat the syndrome Overall design: Bulk RNA sequencing of whole zebrafish larvae at 21 days post-fertilisation (dpf), including wild-type (WT) controls and cachectic tumour-burdened p53 knockout zebrafish with constitutive hepatic YAP overexpression (PY). Samples underwent CRISPR/Cas9-mediated knockouts targeting the melanin transporter SLC45a2 (used as a pigmentation marker), either alone, (SLC45a2-KO), or in combination with the bile acid-responsive metabolic receptor TGR5 (TGR5-KO) or the classical bile acid synthesis enzyme CYP7a1 (CYP7a1-KO).

癌症相关恶病质（Cancer-associated cachexia）是一种以脂肪与肌肉量大幅丢失为特征的严重代谢综合征。尽管临床前模型已推动我们对恶病质的认知，但由于对组织消耗的潜在机制仍缺乏深入解析，目前尚无获批的治疗手段。本研究利用斑马鱼中YAP驱动的肝癌模型——该模型可快速诱发恶病质——揭示了胆汁酸紊乱在恶病质发病过程中一条进化保守的作用通路。空间转录组分析显示，YAP可诱导双谱系胆管癌表型，该表型与胆汁酸失调密切相关。从机制层面，我们证实胆汁酸合成通路（经由CYP7A1）以及通过胆汁酸受体TGR5的信号转导均为恶病质诱导所必需。值得注意的是，我们发现使用奥贝昔班（odevixibat）促进胆汁酸排泄可有效改善恶病质。综上，本研究揭示了YAP介导恶病质的进化保守机制，并为该综合征提出了潜在治疗策略。整体实验设计：对受精后21天（dpf）的斑马鱼幼鱼开展批量RNA测序，样本涵盖野生型（WT）对照组，以及存在恶病质的肿瘤负荷型p53敲除斑马鱼（该模型组成性过表达肝脏YAP，记为PY）。部分样本接受了CRISPR/Cas9介导的基因敲除，靶向黑色素转运蛋白SLC45a2（用作色素标记物），包括单独敲除SLC45a2（SLC45a2-KO），以及同时敲除胆汁酸响应性代谢受体TGR5（TGR5-KO）或经典胆汁酸合成酶CYP7a1（CYP7a1-KO）。