Huang Xiang-Han, Huang Ching-Ying
Department of Food Science and Biotechnology, National Chung Hsing University, Taichung, Taiwan.
NPJ Sci Food. 2024 Oct 1;8(1):71. doi: 10.1038/s41538-024-00318-2.
Recent studies have shown that high dietary fructose intake enhances intestinal tumor growth in mice. Our previous work indicated that glucose enables hypoxic colorectal cancer (CRC) cells to resist receptor-interacting protein (RIP)-dependent necroptosis. Despite having the same chemical formula, glucose and fructose are absorbed through different transporters yet both can enter the glycolytic metabolic pathway. The excessive intake of dietary fructose, leading to its overflow into the colon, allows colonic cells to absorb fructose apically. This study explores the mechanisms behind apical fructose-mediated death resistance in CRC cells under hypoxic stress. Utilizing three CRC cell lines (Caco-2, HT29, and T84) under normoxic and hypoxic conditions with varying fructose concentrations, we assessed lactate dehydrogenase (LDH) activity, RIP1/3 complex formation (a necroptosis marker), and cell integrity. We investigated the role of fructose in glycolytic-mediated death resistance using glycolytic inhibitors iodoacetate (IA, a glycolytic inhibitor to glyceraldehyde 3-phosphate dehydrogenase), and UK5099 (UK, an inhibitor to mitochondrial pyruvate carrier). Our findings reveal that apical fructose prevents the hypoxia-induced RIP-dependent necroptosis in Caco-2 and HT29 cells. Fructose exposure under hypoxia also preserved epithelial integrity. IA, but not UK, blocked fructose-mediated glycolytic metabolite production and necrosis, indicating that anaerobic glycolytic metabolites facilitate death resistance. Notably, fructose treatment upregulated pyruvate kinase (PK)-M1 mRNA in hypoxic Caco-2 and HT29 cells, while PKM2 upregulation was exclusive to HT29 cells. In conclusion, apical fructose utilization through glycolysis effectively inhibits hypoxia-induced RIP-dependent necroptosis in CRC cells, shedding light on potential metabolic adaptation mechanisms in the tumor microenvironment and suggesting novel targets for therapeutic intervention.
最近的研究表明，高膳食果糖摄入量会促进小鼠肠道肿瘤生长。我们之前的研究表明，葡萄糖能使缺氧的结直肠癌（CRC）细胞抵抗受体相互作用蛋白（RIP）依赖性坏死性凋亡。尽管葡萄糖和果糖具有相同的化学式，但它们通过不同的转运体吸收，不过二者均可进入糖酵解代谢途径。膳食果糖的过量摄入会导致其溢流至结肠，使结肠细胞从顶端吸收果糖。本研究探讨了在缺氧应激下顶端果糖介导的CRC细胞抗死亡机制。利用三种CRC细胞系（Caco-2、HT29和T84），在常氧和缺氧条件下，使用不同浓度的果糖，我们评估了乳酸脱氢酶（LDH）活性、RIP1/3复合物形成（一种坏死性凋亡标志物）以及细胞完整性。我们使用糖酵解抑制剂碘乙酸（IA，一种甘油醛-3-磷酸脱氢酶的糖酵解抑制剂）和UK5099（UK，一种线粒体丙酮酸载体抑制剂）研究了果糖在糖酵解介导的抗死亡中的作用。我们的研究结果表明，顶端果糖可防止缺氧诱导的Caco-2和HT29细胞中RIP依赖性坏死性凋亡。缺氧条件下暴露于果糖还能维持上皮完整性。IA而非UK可阻断果糖介导的糖酵解代谢产物生成和坏死，表明无氧糖酵解代谢产物促进抗死亡。值得注意的是，果糖处理使缺氧的Caco-2和HT29细胞中丙酮酸激酶（PK）-M1 mRNA上调，而PKM2上调仅见于HT29细胞。总之，通过糖酵解利用顶端果糖可有效抑制缺氧诱导的CRC细胞中RIP依赖性坏死性凋亡，揭示了肿瘤微环境中潜在的代谢适应机制，并为治疗干预提供了新的靶点。
