VanSant-Webb Chad, Low Hayden K, Kuramoto Junko, Stanley Claire E, Qiang Hantao, Su Audrey, Ross Alexis N, Cooper Chad G, Cox James E, Summers Scott A, Evason Kimberley J, Ducker Gregory S
Department of Pathology, University of Utah School of Medicine. Salt Lake City UT, 84112, USA.
Department of Biochemistry, University of Utah School of Medicine. Salt Lake City UT, 84112, USA.
bioRxiv. 2023 Oct 16:2023.10.12.562134. doi: 10.1101/2023.10.12.562134.
Activating mutations in the gene encoding β-catenin are among the most frequently observed oncogenic alterations in hepatocellular carcinoma (HCC). HCC with mutations show profound alterations in lipid metabolism including increases in fatty acid oxidation and transformation of the phospholipidome, but it is unclear how these changes arise and whether they contribute to the oncogenic program in HCC.
We employed untargeted lipidomics and targeted isotope tracing to quantify phospholipid production fluxes in an inducible human liver cell line expressing mutant β-catenin, as well as in transgenic zebrafish with activated β-catenin-driven HCC.
In both models, activated β-catenin expression was associated with large changes in the lipidome including conserved increases in acylcarnitines and ceramides and decreases in triglycerides. Lipid flux analysis in human cells revealed a large reduction in phosphatidylcholine (PC) production rates as assayed by choline tracer incorporation. We developed isotope tracing lipid flux analysis for zebrafish and observed similar reductions in phosphatidylcholine synthesis flux accomplished by sex-specific mechanisms.
The integration of isotope tracing with lipid abundances highlights specific lipid class transformations downstream of β-catenin signaling in HCC and suggests future HCC-specific lipid metabolic targets.
β-连环蛋白编码基因的激活突变是肝细胞癌（HCC）中最常见的致癌改变之一。携带该突变的HCC在脂质代谢方面表现出深刻变化，包括脂肪酸氧化增加和磷脂组的转变，但尚不清楚这些变化是如何产生的，以及它们是否有助于HCC的致癌进程。
我们采用非靶向脂质组学和靶向同位素示踪技术，对表达突变型β-连环蛋白的诱导性人肝细胞系以及β-连环蛋白激活驱动的HCC转基因斑马鱼中的磷脂生成通量进行定量分析。
在这两种模型中，β-连环蛋白的激活表达均与脂质组的巨大变化相关，包括酰基肉碱和神经酰胺的持续增加以及甘油三酯的减少。通过胆碱示踪掺入法测定，人细胞中的脂质通量分析显示磷脂酰胆碱（PC）生成速率大幅降低。我们开发了斑马鱼的同位素示踪脂质通量分析方法，并观察到通过性别特异性机制实现的磷脂酰胆碱合成通量有类似降低。
同位素示踪与脂质丰度的整合突出了HCC中β-连环蛋白信号下游特定脂质类别的转变，并提示了未来HCC特异性脂质代谢靶点。
