由SLC5A8转运并随后抑制组蛋白去乙酰化酶1（HDAC1）和组蛋白去乙酰化酶3（HDAC3）是3-溴丙酮酸抗肿瘤活性的基础。
Transport by SLC5A8 with subsequent inhibition of histone deacetylase 1 (HDAC1) and HDAC3 underlies the antitumor activity of 3-bromopyruvate.
作者信息
Thangaraju Muthusamy, Karunakaran Senthil K, Itagaki Shiro, Gopal Elangovan, Elangovan Selvakumar, Prasad Puttur D, Ganapathy Vadivel
机构信息
Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, Georgia 30912, USA.
出版信息
Cancer. 2009 Oct 15;115(20):4655-66. doi: 10.1002/cncr.24532.
BACKGROUND
3-bromopyruvate is an alkylating agent with antitumor activity. It is currently believed that blockade of adenosine triphosphate production from glycolysis and mitochondria is the primary mechanism responsible for this antitumor effect. The current studies uncovered a new and novel mechanism for the antitumor activity of 3-bromopyruvate.
METHODS
The transport of 3-bromopyruvate by sodium-coupled monocarboxylate transporter SMCT1 (SLC5A8), a tumor suppressor and a sodium (Na+)-coupled, electrogenic transporter for short-chain monocarboxylates, was studied using a mammalian cell expression and the Xenopus laevis oocyte expression systems. The effect of 3-bromopyruvate on histone deacetylases (HDACs) was monitored using the lysate of the human breast cancer cell line MCF7 and human recombinant HDAC isoforms as the enzyme sources. Cell viability was monitored by fluorescence-activated cell-sorting analysis and colony-formation assay. The acetylation status of histone H4 was evaluated by Western blot analysis.
RESULTS
3-Bromopyruvate is a transportable substrate for SLC5A8, and that transport process is Na+-coupled and electrogenic. MCF7 cells did not express SLC5A8 and were not affected by 3-bromopyruvate. However, when transfected with SLC5A8 or treated with inhibitors of DNA methylation, these cells underwent apoptosis in the presence of 3-bromopyruvate. This cell death was associated with the inhibition of HDAC1/HDAC3. Studies with different isoforms of human recombinant HDACs identified HDAC1 and HDAC3 as the targets for 3-bromopyruvate.
CONCLUSIONS
3-Bromopyruvate was transported into cells actively through the tumor suppressor SLC5A8, and the process was energized by an electrochemical Na+ gradient. Ectopic expression of the transporter in MCF7 cells led to apoptosis, and the mechanism involved the inhibition of HDAC1/HDAC3.
背景
3-溴丙酮酸是一种具有抗肿瘤活性的烷基化剂。目前认为，阻断糖酵解和线粒体产生三磷酸腺苷是这种抗肿瘤作用的主要机制。当前的研究揭示了3-溴丙酮酸抗肿瘤活性的一种全新机制。
方法
使用哺乳动物细胞表达系统和非洲爪蟾卵母细胞表达系统，研究了肿瘤抑制因子、短链单羧酸的钠（Na⁺）偶联、生电转运体——钠偶联单羧酸转运体SMCT1（SLC5A8）对3-溴丙酮酸的转运。以人乳腺癌细胞系MCF7的裂解物和人重组HDAC亚型作为酶源，监测3-溴丙酮酸对组蛋白脱乙酰酶（HDAC）的影响。通过荧光激活细胞分选分析和集落形成试验监测细胞活力。通过蛋白质印迹分析评估组蛋白H4的乙酰化状态。
结果
3-溴丙酮酸是SLC5A8的可转运底物，且该转运过程是Na⁺偶联且生电的。MCF7细胞不表达SLC5A8，不受3-溴丙酮酸影响。然而，当转染SLC5A8或用DNA甲基化抑制剂处理时，这些细胞在3-溴丙酮酸存在的情况下会发生凋亡。这种细胞死亡与HDAC1/HDAC3的抑制有关。对人重组HDAC不同亚型的研究确定HDAC1和HDAC3是3-溴丙酮酸的作用靶点。
结论
3-溴丙酮酸通过肿瘤抑制因子SLC5A8被主动转运到细胞中，该过程由电化学Na⁺梯度提供能量。MCF7细胞中该转运体的异位表达导致细胞凋亡，其机制涉及HDAC1/HDAC3的抑制。
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