Tax impairs DNA replication forks and increases DNA breaks in specific oncogenic genome regions
Tax impairs DNA replication forks and increases DNA breaks in specific oncogenic genome regions
复制标题
DOI：
10.1186/1476-4598-13-205
复制
发表时间：
2014-09-04
期刊：
影响因子：
37.3
通讯作者：
Nicot, Christophe
中科院分区：
文献类型：
--
作者：
Chaib-Mezrag, Hassiba;Lemacon, Delphine;Nicot, Christophe
背景资料：人类T细胞白血病病毒1型（HTLV-I）是一种与成人T细胞白血病（ATL）相关的人类逆转录病毒，ATL是一种预后不良的侵袭性CD 4 T细胞增殖性疾病。这种疾病发展前的长潜伏期和低发病率表明，病毒本身不足以转化，需要遗传缺陷才能为白血病创造一个允许的环境。事实上，ATL细胞的特点是深刻的遗传修饰，包括结构和数量的染色体alterations.Results：在这项研究中，我们使用分子梳理技术来研究癌蛋白税对DNA复制的影响。我们发现，复制叉难以复制复杂的DNA，叉进展较慢，并且在Tax表达存在时更频繁地暂停或停止。我们的研究结果还表明，税收相关的复制缺陷的部分补偿增加射击备份的起源。与Tax对DNA复制的这些影响一致，在Tax表达细胞中观察到双链DNA断裂（DDSB）增加。Tax介导的DDSB增加与Tax激活NF-κ B和刺激细胞内一氧化氮产生的能力相关。我们还证明了在HTLV-I转化的T细胞和ATL细胞中人跨损伤合成（TLS）DNA聚合酶Pol-H和Pol-K的表达减少。这与Tax在特定基因组区域诱导的DNA断裂增加有关，例如c-Myc和Bcl-2主要断裂点。与此一致的概念，即非同源末端连接（NHEJ）途径是过度活跃的HTLV-I转化的细胞，我们发现，抑制NHEJ途径诱导显着的杀伤HTLV-I转化的细胞和患者来源的白血病ATL cells.Conclusion：我们的研究结果表明，复制问题增加遗传不稳定性HTLV-I转化的细胞。因此，滥用NHEJ和有缺陷的同源修复（HR）DNA修复途径可以作为治疗成人T细胞白血病的新治疗方法。
Background: Human T-cell leukemia virus type 1 (HTLV-I) is a human retrovirus associated with adult T-cell leukemia (ATL), an aggressive CD4 T-cell proliferative disease with dismal prognosis. The long latency preceding the development of the disease and the low incidence suggests that the virus itself is not sufficient for transformation and that genetic defects are required to create a permissive environment for leukemia. In fact, ATL cells are characterized by profound genetic modifications including structural and numerical chromosome alterations.Results: In this study we used molecular combing techniques to study the effect of the oncoprotein Tax on DNA replication. We found that replication forks have difficulties replicating complex DNA, fork progression is slower, and they pause or stall more frequently in the presence of Tax expression. Our results also show that Tax-associated replication defects are partially compensated by an increase in the firing of back-up origins. Consistent with these effects of Tax on DNA replication, an increase in double strand DNA breaks (DDSB) was seen in Tax expressing cells. Tax-mediated increases in DDSBs were associated with the ability of Tax to activate NF-kB and to stimulate intracellular nitric oxide production. We also demonstrated a reduced expression of human translesion synthesis (TLS) DNA polymerases Pol-H and Pol-K in HTLV-I-transformed T cells and ATL cells. This was associated with an increase in DNA breaks induced by Tax at specific genome regions, such as the c-Myc and the Bcl-2 major breakpoints. Consistent with the notion that the non-homologous end joining (NHEJ) pathway is hyperactive in HTLV-I-transformed cells, we found that inhibition of the NHEJ pathway induces significant killing of HTLV-I transformed cells and patient-derived leukemic ATL cells.Conclusion: Our results suggest that, replication problems increase genetic instability in HTLV-I-transformed cells. As a result, abuse of NHEJ and a defective homologous repair (HR) DNA repair pathway can be targeted as a new therapeutic approach for the treatment of adult T-cell leukemia.