Genotoxicity of Cytolethal Distending Toxin (CDT) on Isogenic Human Colorectal Cell Lines: Potential Promoting Effects for Colorectal Carcinogenesis
Genotoxicity of Cytolethal Distending Toxin (CDT) on Isogenic Human Colorectal Cell Lines: Potential Promoting Effects for Colorectal Carcinogenesis
复制标题
DOI：
10.3389/fcimb.2016.00034
复制
发表时间：
2016-03-23
影响因子：
5.7
通讯作者：
Vignard, Julien
中科院分区：
文献类型：
--
作者：
Graillot, Vanessa;Dormoy, Inge;Vignard, Julien
人类微生物群的组成影响肿瘤的发生，特别是在结直肠癌（CRC）中。致病性大肠杆菌具有多种致毒因子，其中包括细胞致死膨胀毒素（CDT）。CDT在多种哺乳动物细胞中具有双重DNA酶和磷酸酶活性，可诱导DNA双链断裂、细胞周期阻滞和细胞凋亡。由于CDT可以促进恶性转化，我们研究了急性和慢性暴露于大肠杆菌CDT对正常人结肠上皮细胞（HCECs）诱导的细胞结果。此外，我们对正常HCECs的等基因衍生物细胞系进行了比较研究，以模拟在CRC遗传模型中发现的三个主要基因的突变：APC、KRAS和TP53。我们的研究结果表明，APC和p53缺陷细胞在CDT暴露后表现出受损的DNA损伤反应，而表达致癌KRAS（V12）的HCECs对CDT更具抗性。与正常的HCECs相比，癌前衍生物在长期暴露于CDT后表现出恶性转化的特征。通过微核形成试验评估，APC和p53缺陷的HCECs表现出锚定独立生长和遗传不稳定性增强。相比之下，KRAS(V12) HCECs的独立生长能力不受CDT慢性暴露的影响，但微核形成显著增加。因此，CDT本身不会引发CRC，但可能在癌前HCECs中具有促进作用，涉及与CRC相关的遗传改变功能的不同机制。
The composition of the human microbiota influences tumorigenesis, notably in colorectal cancer (CRC). Pathogenic Escherichlacoli possesses a variety of virulent factors, among them the Cytolethal Distending Toxin (CDT). CDT displays dual DNase and phosphatase activities and induces DNA double strand breaks, cell cycle arrest and apoptosis in a broad range of mammalian cells. As CDT could promote malignant transformation, we investigated the cellular outcomes induced by acute and chronic exposures to E. coli CDT in normal human colon epithelial cells (HCECs). Moreover, we conducted a comparative study between isogenic derivatives cell lines of the normal HCECs in order to mimic the mutation of three major genes found in CRC genetic models: APC, KRAS, and TP53. Our results demonstrate that APC and p53 deficient cells showed impaired DNA damage response after CDT exposure, whereas HCECs expressing oncogenic KRAS(V12) were more resistant to CDT. Compared to normal HCECs, the precancerous derivatives exhibit hallmarks of malignant transformation after a chronic exposure to CDT. HCECs defective in APC and p53 showed enhanced anchorage independent growth and genetic instability, assessed by the micronucleus formation assay. In contrast, the ability to grow independently of anchorage was not impacted by CDT chronic exposure in KRAS(V12) HCECs, but micronucleus formation is dramatically increased. Thus, CDT does not initiate CRC by itself, but may have promoting effects in premalignant HCECs, involving different mechanisms in function of the genetic alterations associated to CRC.