Wuxi School of Medicine, Jiangnan University, Wuxi, 214122, Jiangsu Province, China.
School of Food Science and Technology, Jiangnan University, Wuxi, 214122, Jiangsu Province, China.
Eur J Nutr. 2022 Dec;61(8):4059-4075. doi: 10.1007/s00394-022-02940-w. Epub 2022 Jul 9.
Ferroptosis is a form of regulated cell death that has the potential to be targeted as a cancer therapeutic strategy. But cancer cells have a wide range of sensitivities to ferroptosis, which limits its therapeutic potential. Accumulation of lipid peroxides determines the occurrence of ferroptosis. However, the type of lipid involved in peroxidation and the mechanism of lipid peroxide accumulation are less studied.
The effects of fatty acids (10 μM) with different carbon chain length and unsaturation on ferroptosis were evaluated by MTT and LDH release assay in cell lines derived from prostate cancer (PC3, 22RV1, DU145 and LNCaP), colorectal cancer (HT-29), cervical cancer (HeLa) and liver cancer (HepG2). Inhibitors of apoptosis, necroptosis, autophagy and ferroptosis were used to determine the type of cell death. Then the regulation of reactive oxygen species (ROS) and lipid peroxidation by docosahexaenoic acid (DHA) was measured by HPLC-MS and flow cytometry. The avtive form of DHA was determined by siRNA mediated gene silencing. The role of lipoxygenases was checked by inhibitors and gene silencing. Finally, the effect of DHA on ferroptosis-mediated tumor killing was verified in xenografts.
The sensitivity of ferroptosis was positively correlated with the unsaturation of exogenously added fatty acid. DHA (22:6 n-3) sensitized cancer cells to ferroptosis-inducing reagents (FINs) at the highest level in vitro and in vivo. In this process, DHA increased ROS accumulation, lipid peroxidation and protein oxidation independent of its membrane receptor, GPR120. Inhibition of long chain fatty acid-CoA ligases and lysophosphatidylcholine acyltransferases didn't affect the role of DHA. DHA-involved ferroptosis can be induced in both arachidonate lipoxygenase 5 (ALOX5) negative and positive cells. Down regulation of ALOX5 inhibited ferroptosis, while overexpression of ALOX5 promoted ferroptosis.
DHA can effectively promote ferroptosis-mediated tumor killing by increasing intracellular lipid peroxidation. Both ALOX5 dependent and independent pathways are involved in DHA-FIN induced ferroptosis. And during this process, free DHA plays an important role.
铁死亡是一种受调控的细胞死亡形式，具有作为癌症治疗策略的潜力。但是，癌症细胞对铁死亡的敏感性范围很广，这限制了其治疗潜力。脂质过氧化物的积累决定了铁死亡的发生。然而，参与过氧化的脂质类型和脂质过氧化物积累的机制研究较少。
通过 MTT 和 LDH 释放试验，评估了具有不同碳链长度和不饱和度的脂肪酸（10 μM）对前列腺癌（PC3、22RV1、DU145 和 LNCaP）、结直肠癌（HT-29）、宫颈癌（HeLa）和肝癌（HepG2）细胞系中铁死亡的影响。使用凋亡、坏死、自噬和铁死亡抑制剂来确定细胞死亡类型。然后通过 HPLC-MS 和流式细胞术测量二十二碳六烯酸（DHA）对活性氧（ROS）和脂质过氧化的调节。通过 siRNA 介导的基因沉默来确定 DHA 的活性形式。通过抑制剂和基因沉默检查脂氧合酶的作用。最后，在异种移植模型中验证了 DHA 对铁死亡介导的肿瘤杀伤的作用。
铁死亡的敏感性与外源性添加脂肪酸的不饱和程度呈正相关。DHA（22:6 n-3）在体外和体内均以最高水平使癌症细胞对铁死亡诱导剂（FINs）敏感。在此过程中，DHA 增加了 ROS 积累、脂质过氧化和蛋白质氧化，而不依赖于其膜受体 GPR120。长链脂肪酸-CoA 连接酶和溶血磷脂酰胆碱酰基转移酶的抑制作用不影响 DHA 的作用。DHA 参与的铁死亡可在花生四烯酸脂氧合酶 5（ALOX5）阴性和阳性细胞中诱导。下调 ALOX5 抑制铁死亡，而过表达 ALOX5 则促进铁死亡。
DHA 通过增加细胞内脂质过氧化作用，有效地促进铁死亡介导的肿瘤杀伤。DHA-FIN 诱导的铁死亡涉及 ALOX5 依赖性和非依赖性途径，在此过程中，游离 DHA 发挥重要作用。
