Department of Life Sciences, National Central University, Taoyuan, Taiwan; Department of Natural Science Education, University of Trunojoyo Madura, East Java, Indonesia.
Division of Gastroenterology and Hepatology, Department of Internal Medicine, Landseed International Hospital, Taoyuan, Taiwan.
Chem Biol Interact. 2022 Sep 25;365:110046. doi: 10.1016/j.cbi.2022.110046. Epub 2022 Jul 19.
Selenocystine (SeC) has been identified as a novel compound with broad-spectrum anticancer activity. However, the effects of SeC on modifying DNA repair mechanism were less addressed. In this study, we demonstrated that SeC selectively induced cytotoxicity and genotoxicity against HepG2 hepatoma cell line. Comet assay revealed SeC-induced DNA damage in HepG2 cells, particularly in the form of DNA double strand breaks (DSBs), corroborated by the increase expression of the DSB marker, gamma-H2AX. We further demonstrated that SeC suppressed DNA homologous recombination repair, exacerbating DNA damage accumulation. Such effects on DNA damage and cell viability inhibition were alleviated by antioxidants, glutathione and Trolox, suggesting the involvement of reactive oxygen species (ROS). High levels of intracellular and mitochondrial ROS were detected in SeC-treated HepG2. In addition, SeC impaired the expression of antioxidant enzymes (superoxidase mutases and catalase), prompting the imbalance between antioxidant protection and excessive ROS formation and eliciting DSBs and cellular death. Decreased procaspase-3, 7, and 9 and Bcl-2 proteins and an increased Bax/Bcl-2 ratio, were observed after SeC treatment, but could be reversed by Torlox, confirming the action of SeC on ROS-induced apoptosis. In vivo, the xenograft tumor model of HepG2 cells validated the inhibition of SeC on tumor growth, and the induction of DSBs and apoptosis. In summary, SeC has the capability to induce ROS-dependent DNA damage and impeded DBS repair in HepG2 cells. Thus, SeC holds great promise as a therapeutic or adjuvant agent targeting DNA repair for cancer treatment.
硒代半胱氨酸（SeC）已被鉴定为一种具有广谱抗癌活性的新型化合物。然而，其对修饰 DNA 修复机制的影响尚未得到充分关注。在本研究中，我们证实 SeC 选择性诱导 HepG2 肝癌细胞系产生细胞毒性和遗传毒性。彗星试验显示，SeC 诱导 HepG2 细胞发生 DNA 损伤，特别是 DNA 双链断裂（DSBs），这一结果与 DSB 标志物γ-H2AX 表达增加相符。我们进一步证明，SeC 抑制 DNA 同源重组修复，加剧 DNA 损伤积累。抗氧化剂谷胱甘肽和 Trolox 可减轻这些对 DNA 损伤和细胞活力抑制的影响，提示活性氧（ROS）的参与。在 SeC 处理的 HepG2 细胞中检测到高水平的细胞内和线粒体 ROS。此外，SeC 损害抗氧化酶（超氧化物歧化酶和过氧化氢酶）的表达，促使抗氧化保护与过量 ROS 形成之间的失衡，并引发 DSBs 和细胞死亡。在 SeC 处理后，观察到 procaspase-3、7 和 9 以及 Bcl-2 蛋白减少，Bax/Bcl-2 比值增加，但 Trolox 可逆转这一现象，证实了 SeC 对 ROS 诱导的细胞凋亡的作用。在体内，HepG2 细胞的异种移植肿瘤模型验证了 SeC 对肿瘤生长的抑制作用，以及 DSBs 和细胞凋亡的诱导作用。综上所述，SeC 具有诱导 ROS 依赖性 DNA 损伤和阻碍 HepG2 细胞 DSB 修复的能力。因此，SeC 有望成为一种针对癌症治疗中 DNA 修复的治疗或辅助药物。
