Ivanova Donika, Semkova Severina, Yaneva Zvezdelina, Nikolova Biliana, Zhelev Zhivko, Bakalova Rumiana, Aoki Ichio
Department of Pharmacology, Animal Physiology, Biochemistry and Chemistry, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria.
Department of Chemistry and Biochemistry, Faculty of Medicine, Trakia University, Stara Zagora, Bulgaria.
Anticancer Res. 2023 Mar;43(3):1213-1220. doi: 10.21873/anticanres.16268.
BACKGROUND/AIM: Mitochondria-targeted anticancer drugs ("mitocans") of natural origin are attractive candidates as adjuvants in cancer therapy. The redox couple menadione/ascorbate (M/A), which belongs to the "mitocans" family, induces selective oxidative stress in cancerous mitochondria and cells, respectively. DHA has also been found to regulate the mevalonate pathway, which is closely related to the prenylation of the cytotoxic menadione to the non-cytotoxic menaquinone. The aim of this study was to elucidate the ability of docosahexaenoic acid (DHA) to potentiate the anticancer effect of M/A by increasing ROS production, as well as affecting steady-state ATP levels in cancer cells.
The experiments were performed on leukemic lymphocyte Jurkat. Cells were treated with DHA, M/A, and their combination (M/A/DHA) and four parameters were examined using the following assays: cell viability and proliferation, steady-state ATP, mitochondrial superoxide, intracellular hydroperoxides. Three independent experiments with two or six parallel measurements were performed for each parameter.
The triple combination M/A/DHA was characterized by much higher antiproliferative activity and cytotoxicity than M/A and DHA administered alone. DHA significantly accelerated M/A-induced ATP depletion in cells, which was accompanied by an additional increase in mitochondrial superoxide compared to cells treated with M/A or DHA alone.
DHA significantly enhanced M/A-induced cytotoxicity in leukemic lymphocytes by inducing severe mitochondrial oxidative stress and accelerated ATP depletion. Selective DHA-mediated suppression of cholesterol synthesis in cancer cells (involved in the prenylation of cytotoxic menadione to the less cytotoxic phylloquinone), as well as DHA-mediated inhibition of superoxide dismutase are suggested to underlie the potentiation of the anticancer effect of M/A.
背景/目的：天然来源的线粒体靶向抗癌药物（“线粒体靶向剂”）是癌症治疗中作为佐剂的有吸引力的候选药物。属于“线粒体靶向剂”家族的氧化还原对甲萘醌/抗坏血酸（M/A）分别在癌性线粒体和细胞中诱导选择性氧化应激。还发现二十二碳六烯酸（DHA）可调节甲羟戊酸途径，该途径与细胞毒性甲萘醌异戊烯基化形成非细胞毒性甲萘醌密切相关。本研究的目的是阐明二十二碳六烯酸（DHA）通过增加活性氧（ROS）生成以及影响癌细胞中的稳态ATP水平来增强M/A抗癌作用的能力。
实验在白血病淋巴细胞Jurkat上进行。用DHA、M/A及其组合（M/A/DHA）处理细胞，并使用以下测定法检测四个参数：细胞活力和增殖、稳态ATP、线粒体超氧化物、细胞内过氧化氢。对每个参数进行了三个独立实验，每个实验有两个或六个平行测量。
三联组合M/A/DHA的特征是抗增殖活性和细胞毒性比单独施用的M/A和DHA高得多。DHA显著加速了M/A诱导的细胞内ATP消耗，与单独用M/A或DHA处理的细胞相比，这伴随着线粒体超氧化物的额外增加。
DHA通过诱导严重的线粒体氧化应激和加速ATP消耗，显著增强了M/A对白血病淋巴细胞的细胞毒性。推测癌细胞中DHA介导的胆固醇合成选择性抑制（涉及细胞毒性甲萘醌异戊烯基化形成细胞毒性较小的叶绿醌）以及DHA介导的超氧化物歧化酶抑制是M/A抗癌作用增强的基础。
