多不饱和脂肪酸（PUFAs）是膜磷脂的结构成分，也是氧化脂质介质的前体，具有多种功能，包括控制细胞生长、炎症和肿瘤发生。然而，控制PUFAs在脂质介质产生中可用性的分子途径尚不明确。在这里，我们研究了三个途径在PUFAs为脂质介质产生提供中的相互作用：(i)分泌的X组磷脂酶A2（GX sPLA2）和(ii)胞内的IVA组磷脂酶A2（cPLA2α），它们都从膜磷脂中解放PUFAs，并且(iii)脂肪三酸甘油酯脂肪酶（ATGL），它介导存储在胞质脂滴中的三酰基甘油（TAGs）的降解。我们结合脂质组学和功能分析在癌细胞系模型中，解剖了PUFAs在膜磷脂和脂质滴之间的交通，并确定了这些途径在脂质介质产生、癌细胞增殖和肿瘤生长中的作用。我们证明，脂质介质产生在很大程度上依赖于TAG的转化率。GX sPLA2将ω-3和ω-6 PUFAs从膜磷脂导向TAG贮存中，而ATGL则需要其进入脂质介质生物合成途径。ATGL控制着LD贮存中PUFAs的释放以及在充足营养和饥饿条件下将其转化为环氧合酶和过氧化酶衍生的脂质介质。在饥饿的细胞中，ATGL还促进了LD衍生PUFAs进入磷脂中，成为cPLA2α的底物。此外，我们证明，通过酰基辅酶A：二酰基甘油酰基转移酶1（DGAT1）增加TAG贮存对于产生促进癌细胞增殖和肿瘤生长的有丝分裂原脂信号是必需的。该研究转变了PLA2驱动的脂质介质信号传导的范式，并将LDs确定为中央脂质介质产生中心。靶向DGAT1介导的LD生物发生是限制脂质介质产生和肿瘤生长的有希望的策略。版权所有©2023 The Author(s)。由Elsevier GmbH出版。保留所有权利。

Polyunsaturated fatty acids (PUFAs) are structural components of membrane phospholipids and precursors of oxygenated lipid mediators with diverse functions, including the control of cell growth, inflammation and tumourigenesis. However, the molecular pathways that control the availability of PUFAs for lipid mediator production are not well understood. Here, we investigated the crosstalk of three pathways in the provision of PUFAs for lipid mediator production: (i) secreted group X phospholipase A2 (GX sPLA2) and (ii) cytosolic group IVA PLA2 (cPLA2α), both mobilizing PUFAs from membrane phospholipids, and (iii) adipose triglyceride lipase (ATGL), which mediates the degradation of triacylglycerols (TAGs) stored in cytosolic lipid droplets (LDs).We combined lipidomic and functional analyses in cancer cell line models to dissect the trafficking of PUFAs between membrane phospholipids and LDs and determine the role of these pathways in lipid mediator production, cancer cell proliferation and tumour growth in vivo.We demonstrate that lipid mediator production strongly depends on TAG turnover. GX sPLA2 directs ω-3 and ω-6 PUFAs from membrane phospholipids into TAG stores, whereas ATGL is required for their entry into lipid mediator biosynthetic pathways. ATGL controls the release of PUFAs from LD stores and their conversion into cyclooxygenase- and lipoxygenase-derived lipid mediators under conditions of nutrient sufficiency and during serum starvation. In starving cells, ATGL also promotes the incorporation of LD-derived PUFAs into phospholipids, representing substrates for cPLA2α. Furthermore, we demonstrate that the built-up of TAG stores by acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is required for the production of mitogenic lipid signals that promote cancer cell proliferation and tumour growth.This study shifts the paradigm of PLA2-driven lipid mediator signalling and identifies LDs as central lipid mediator production hubs. Targeting DGAT1-mediated LD biogenesis is a promising strategy to restrict lipid mediator production and tumour growth.Copyright © 2023 The Author(s). Published by Elsevier GmbH.. All rights reserved.