Laboratory of Clinical Pharmaceutics & Therapeutics, Division of Pharmasciences, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
Laboratory of Clinical Pharmaceutics & Therapeutics, Division of Pharmasciences, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan;
Anticancer Res. 2023 Mar;43(3):1113-1120. doi: 10.21873/anticanres.16256.
BACKGROUND/AIM: Monocarboxylate transporters (MCTs) transport short-chain monocarboxylates, such as lactate, and have been reported to be related to poor prognosis in breast cancer. Our previous studies showed that a high glucose state altered MCT expression and changed the sensitivity of the tamoxifen active metabolite 4-hydroxytamoxifen (4-OHT) via hypoxia-inducible factor-1α (HIF-1α) protein expression. We hypothesized that MCT inhibitors affect 4-OHT-induced cytotoxicity under normal glucose conditions by decreasing HIF-1α protein expression. To test this hypothesis, we evaluated the combined effect of MCT inhibitor and 4-OHT using the estrogen receptor (ER)-positive breast cancer cell line MCF-7, under normal glucose conditions.
Expression of MCTs and oxidative stress markers was evaluated by real-time PCR. Cell viability was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Reactive oxygen species (ROS) were measured using the cell permeability probe 2',7'-dichlorodihydrofluorescein diacetate.
MCT1 expression increased under normal glucose conditions. The MCT1 substrate/inhibitor, 5-oxoproline (5-OP), enhanced 4-OHT-induced cytotoxicity. Bindarit, a selective MCT4 inhibitor, decreased 4-OHT sensitivity, similar to results of our previous study under high glucose conditions. In contrast, the combination of 5-OP and 4-OHT decreased ATP levels compared with that by 4-OHT alone in MCF-7 cells. Furthermore, 5-OP significantly increased the ROS production induced by 4-OHT.
5-OP enhances 4-OHT-induced cytotoxicity in ER-positive breast cancer cells under normal glucose conditions.
背景/目的：单羧酸转运蛋白（MCT）运输短链单羧酸，如乳酸，并与乳腺癌不良预后相关。我们之前的研究表明，高糖状态改变了 MCT 的表达，并通过缺氧诱导因子-1α（HIF-1α）蛋白表达改变了他莫昔芬活性代谢物 4-羟基他莫昔芬（4-OHT）的敏感性。我们假设 MCT 抑制剂通过降低 HIF-1α 蛋白表达，在正常葡萄糖条件下影响 4-OHT 诱导的细胞毒性。为了验证这一假设，我们在正常葡萄糖条件下，使用雌激素受体（ER）阳性乳腺癌细胞系 MCF-7 评估了 MCT 抑制剂和 4-OHT 的联合作用。
通过实时 PCR 评估 MCTs 和氧化应激标志物的表达。使用 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）测量细胞活力。使用细胞通透性探针 2',7'-二氯二氢荧光素二乙酸酯测量活性氧（ROS）。
在正常葡萄糖条件下，MCT1 表达增加。MCT1 底物/抑制剂 5-氧脯氨酸（5-OP）增强了 4-OHT 诱导的细胞毒性。Bindarit，一种选择性 MCT4 抑制剂，降低了 4-OHT 的敏感性，与我们之前在高糖条件下的研究结果相似。相比之下，与单独使用 4-OHT 相比，5-OP 和 4-OHT 的组合使 MCF-7 细胞中的 ATP 水平降低。此外，5-OP 显著增加了 4-OHT 诱导的 ROS 产生。
在正常葡萄糖条件下，5-OP 增强了 ER 阳性乳腺癌细胞中 4-OHT 诱导的细胞毒性。
