Inhibition of the DNA-dependent protein kinase catalytic subunit radiosensitizes malignant gliorna cells by inducing autophagy
Inhibition of the DNA-dependent protein kinase catalytic subunit radiosensitizes malignant gliorna cells by inducing autophagy
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DOI：
10.1158/0008-5472.can-04-4202
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发表时间：
2005-05-15
期刊：
影响因子：
11.2
通讯作者：
Kondo, Y
中科院分区：
文献类型：
--
作者：
Daido, S;Yamamoto, A;Kondo, Y
DNA依赖性蛋白激酶（DNA- pk）在电离辐射（IR）诱导的DNA双链断裂修复中起重要作用。缺乏DNA- pk导致DNA双链断裂修复缺陷和放射致敏。一般认为，IR诱导的细胞死亡是凋亡。另一方面，非凋亡性细胞死亡，即自噬，作为癌细胞对化疗和IR的一种新的反应，近年来引起了人们的关注。自噬是一种蛋白质降解系统，其特征是在细胞质中显著形成双膜泡。然而，关于DNA-PK和ir诱导的自噬之间的关系，我们知之甚少。本研究以人恶性胶质瘤M059J和M059K细胞为研究对象，探讨DNA-PK在ir诱导的细胞凋亡和自噬性死亡中的作用。低剂量IR诱导缺乏DNA-PK催化亚基（DNA-PKcs）的M059J细胞大量自噬死亡。DNA-PKcs表达正常的M059K细胞与M059J细胞相对应，尽管有一小部分细胞发生凋亡，但大多数M059K细胞存活并增殖。低剂量IR抑制p70（S6K）的磷酸化，p70（S6K）是哺乳动物雷帕霉素靶蛋白的下游分子，与M059J细胞的自噬有关，但在M059K细胞中没有。用DNA-PKcs反义寡核苷酸处理M059K细胞可引起辐射诱导的自噬，使细胞具有放射致敏性。此外，抗DNA-PKcs的反义寡核苷酸通过诱导自噬，对其他具有DNA-PK活性的恶性胶质瘤细胞株U373-MG和T98G具有放射致敏作用。特异性抑制DNA-PKcs可能是一种通过诱导自噬使恶性胶质瘤细胞放射增敏的新疗法。
DNA-dependent protein kinase (DNA-PK) plays a major role in the repair of DNA double-strand breaks induced by ionizing radiation (IR). Lack of DNA-PK causes defective DNA double-strand break repair and radiosensitization. In general, the cell death induced by IR is considered to be apoptotic. On the other hand, nonapoptotic cell death, autophagy, has recently attracted attention as a novel response of cancer cells to chemotherapy and IR. Autophagy is a protein degradation system characterized by a prominent formation of double-membrane vesicles in the cytoplasm. Little is known, however, regarding the relationship between DNA-PK and IR-induced autophagy. In the present study, we used human malignant glioma M059J and M059K cells to investigate the role of DNA-PK in IR-induced apoptotic and autophagic cell death. Low-dose IR induced massive autophagic cell death in M059J cells that lack the catalytic subunit of DNA-PK (DNA-PKcs). Most M059K cells, the counterpart of M059J cells in which DNA-PKcs are expressed at normal levels, survived, and proliferated although a small portion of the cells underwent apoptosis. Low-dose IR inhibited the phosphorylation of p70(S6K), a molecule downstream of the mammalian target of rapamycin associated with autophagy in M059J cells but not in M059K cells. The treatment of M059K cells with antisense oligonucleotides against DNA-PKcs caused radiation-induced autophagy and radiosensitized the cells. Furthermore, antisense oligonucleotides against DNA-PKcs radiosensitized other malignant glioma cell lines with DNA-PK activity, U373-MG and T98G, by inducing autophagy. The specific inhibition of DNA-PKcs may be promising as a new therapy to radiosensitize malignant glioma cells by inducing autophagy.