Proteomics Study Reveals That Docosahexaenoic and Arachidonic Acids Exert Different <i>In Vitro</i> Anticancer Activities in Colorectal Cancer Cells

Two polyunsaturated fatty acids, docosahexaenoic acid (DHA) and arachidonic acid (ARA), as well as derivatives, such as eicosanoids, regulate different activities, affecting transcription factors and, therefore, DNA transcription, being a critical step for the functioning of fatty-acid-derived signaling. This work has attempted to determine the in vitro anticancer activities of these molecules linked to the gene transcription regulation of HT-29 colorectal cancer cells. We applied the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test along with lactate dehydrogenase and caspase-3 assays; proteome changes were assessed by “sequential windowed acquisition of all theoretical mass spectra” quantitative proteomics, followed by pathway analysis, to determine the affected molecular mechanisms. In all assays, DHA inhibited cell proliferation of HT-29 cells to a higher extent than ARA and acted primarily by downregulating proteasome particles, while ARA presented a dramatic effect on all six DNA replication helicase particles. The results indicated that both DHA and ARA are potential chemopreventive agent candidates.两种多不饱和脂肪酸——二十二碳六烯酸（DHA）与花生四烯酸（ARA）及其衍生物（如类二十烷酸）可调控多种生理活动，通过影响转录因子进而作用于DNA转录，这是脂肪酸衍生信号通路发挥功能的关键步骤。本研究旨在探究上述分子针对HT-29结肠癌细胞的体外抗癌活性，及其对该细胞基因转录的调控效应。实验中，我们采用3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐实验，联合乳酸脱氢酶与半胱氨酸天冬氨酸蛋白酶3检测进行分析；同时通过“顺序窗口获取所有理论质谱”定量蛋白质组学（SWATH-MS）技术评估蛋白质组变化，并辅以通路分析以明确其调控的分子机制。结果显示，DHA对HT-29细胞增殖的抑制效果优于ARA，其主要作用途径为下调蛋白酶体颗粒的表达；而ARA则对全部六种DNA复制解旋酶颗粒均表现出显著调控作用。本研究结果表明，DHA与ARA均为潜在的化学预防候选制剂。