8-Chloroadenosine is an RNA-directed purine nucleoside analog that induces apoptotic cell death by either inhibiting the transcription of anti-apoptotic proteins or reducing the concentration of intracellular ATP[1-3]. 8-Chloroadenosine activity is dependent on adenosine kinase and requires intracellular accumulation of 8-Chloroadenosine as mono-, di-, and tri-phosphates[3].
In vitro, BT-474 cells were treated with 10μM 8-Chloroadenosine for various durations (0, 4, 8, 12, 16, 24, 48, 72 hours for Thr172, and 0, 4, 8, 12, 16, 24 hours for Ser79). The phosphorylation of AMPK (Thr172) was induced in a time-dependent manner and could be detected within 7-12 hours. Meanwhile, Acetyl-CoA Carboxylase (ACC) phosphorylation at Ser79, one of the key downstream substrates of AMPK, was induced within 4 hours of 8-Chloroadenosine treatment[4]. Exposure of human lung cancer cell lines A549 (p53-wt) and H1299 (p53-depleted) to 8-Chloroadenosine (0, 0.02, 0.2, 2, and 20μM; 24, 48, 72, or 96h) induced cell arrest in the G2/M phase, which was accompanied by accumulation of binucleated and polymorphonucleated cells resulting from aberrant mitosis and failed cytokinesis, depending on time and dose[5]. Treatment of H1299 (p53-null) cells with 8-Chloroadenosine (10μM) for 0, 12, 24, and 48 hours led to an increase in γ-H2AX foci and a time-dependent elevation in γ-H2AX protein levels[6].
In vivo, treated female athymic nude mice with 8-Chloroadenosine (100mg/kg; i.p.), the growth of BT-474 tumors was inhibited, and no macroscopically detectable tumors were observed in 9 of the mice after 3 weeks of treatment[4]. In mice bearing ascitic leukemia L-1210, treatment with 8-Chloroadenosine via intraperitoneal (i.p.) and intravenous (i.v.) injection at a dose of 100mg/kg/day for 7 days resulted in life-prolonging rates of 124.0%±22.1% (P<0.01) and 104.2%±20.1% (P<0.01), respectively[7].
References:
[1] Dennison JB, Ayres ML, Kaluarachchi K, Plunkett W, Gandhi V. Intracellular succinylation of 8-chloroadenosine and its effect on fumarate levels. J Biol Chem. 2010;285(11):8022-8030.
[2] Cottrell KA, Torres LS, Dizon MG, Weber JD. 8-azaadenosine and 8-chloroadenosine are not selective inhibitors of ADAR. Cancer Res Commun. 2021;1(2):56-64.
[3] Tang V, Fu S, Rayner BS, Hawkins CL. 8-Chloroadenosine induces apoptosis in human coronary artery endothelial cells through the activation of the unfolded protein response. Redox Biol. 2019;26:101274.
[4] Stellrecht CM, Vangapandu HV, Le XF, Mao W, Shentu S. ATP directed agent, 8-chloro-adenosine, induces AMP activated protein kinase activity, leading to autophagic cell death in breast cancer cells. J Hematol Oncol. 2014;7:23.
[5] Zhang HY, Gu YY, Li ZG, et al. Exposure of human lung cancer cells to 8-chloro-adenosine induces G2/M arrest and mitotic catastrophe. Neoplasia. 2004;6(6):802-812.
[6] Han YY, Zhou Z, Cao JX, et al. E2F1-mediated DNA damage is implicated in 8-Cl-adenosine-induced chromosome missegregation and apoptosis in human lung cancer H1299 cells. Mol Cell Biochem. 2013;384(1-2):187-196.
[7] Fang J, Shi Y, Zhang L. [Antitumor activities of 8-chloroadenosine in vivo and in vitro]. Zhonghua Zhong Liu Za Zhi. 1995;17(1):5–8. pmid:7656789.
8-Chloroadenosine是一种针对RNA的嘌呤核苷类似物，通过抑制抗凋亡蛋白的转录或降低细胞内ATP浓度来诱导凋亡细胞死亡[1-3]。8-Chloroadenosine的活性依赖于腺苷激酶，并需要细胞内积累8-Chloroadenosine的单磷酸、二磷酸和三磷酸形式[3]。
在体外实验中，BT-474细胞用10μM的8-Chloroadenosine处理不同时间（检测Thr172时为0、4、8、12、16、24、48、72小时；检测Ser79时为0、4、8、12、16、24小时）。AMPK（Thr172）的磷酸化以时间依赖性方式被诱导，并在7-12小时内被检测到。同时，AMPK的关键下游底物之一乙酰辅酶A羧化酶（ACC）在Ser79位点的磷酸化在8-Chloroadenosine处理后4小时内被诱导[4]。人肺癌细胞系A549（p53野生型）和H1299（p53缺失型）暴露于8-Chloroadenosine（0、0.02、0.2、2和20μM；24、48、72或96小时）后，细胞在G2/M期停滞，伴随着由于异常有丝分裂和细胞质分裂失败而导致的双核和多形核细胞的积累，具体取决于时间和剂量[5]。用10μM的8-Chloroadenosine处理H1299（p53缺失型）细胞（0、12、24和48小时），导致γ-H2AX焦点增加，γ-H2AX蛋白水平呈时间依赖性上升[6]。
在体内实验中，对雌性无胸腺裸鼠进行8-Chloroadenosine处理（100mg/kg；腹腔注射），抑制了BT-474肿瘤的生长，且在治疗3周后，9只小鼠中未检测到肉眼可见的肿瘤[4]。在携带腹水白血病L-1210的小鼠中，通过腹腔注射（i.p.）和静脉注射（i.v.）以100mg/kg/天的剂量给予8-Chloroadenosine，持续7天，小鼠的生存期延长率分别为124.0%±22.1%（P<0.01）和104.2%±20.1%（P<0.01）[7]。