芳基烃受体 (AhR) 在细胞间接触和肿瘤生长中的调节作用。

The aryl hydrocarbon receptor (AhR) in the regulation of cell-cell contact and tumor growth.

机构信息

Institute of Toxicology, Medical Center of the Johannes Gutenberg-University, Mainz, Germany.

出版信息

Carcinogenesis. 2010 Aug;31(8):1319-28. doi: 10.1093/carcin/bgq028. Epub 2010 Jan 27.

Abstract

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor, which is activated by a large group of environmental pollutants including polycyclic aromatic hydrocarbons, dioxins and planar polychlorinated biphenyls. Ligand binding leads to dimerization of the AhR with aryl hydrocarbon receptor nuclear translocator and transcriptional activation of several xenobiotic phase I and phase II metabolizing enzymes, such as cytochrome P4501A1 and glutathione-S-transferase, respectively. Since phase I enzymes convert inert carcinogens to active genotoxins, the AhR plays a key role in tumor initiation. Besides this classical route, the AhR mediates tumor promotion and recent evidence suggests that the AhR also plays a role in tumor progression. To date, no mechanistic link could be established between the canonical pathway involving xenobiotic metabolism and AhR-dependent tumor promotion and progression. A hallmark of tumor promotion is unbalanced proliferation, whereas tumor progression is characterized by dedifferentiation, increased motility and metastasis of tumor cells. Tumor progression and presumably also tumor promotion are triggered by loss of cell-cell contact. Cell-cell contact is known to be a critical regulator of proliferation, differentiation and cell motility in vitro and in vivo. Increasing evidence suggests that activation of the AhR may lead to deregulation of cell-cell contact, thereby inducing unbalanced proliferation, dedifferentiation and enhanced motility. In line with this is the finding of increased AhR expression and malignancy in some animal and human cancers. Here, we summarize our current knowledge on non-canonical AhR-driven pathways being involved in deregulation of cell-cell contact and discuss the data with respect to tumor initiation, promotion and progression.

摘要

芳香烃受体 (AhR) 是一种配体依赖性转录因子,可被包括多环芳烃、二恶英和平面型多氯联苯在内的大量环境污染物激活。配体结合导致 AhR 与芳香烃受体核转位蛋白二聚化,并分别激活几种外源物 I 相和 II 相代谢酶,如细胞色素 P4501A1 和谷胱甘肽-S-转移酶。由于 I 相酶将惰性致癌剂转化为活性遗传毒素,因此 AhR 在肿瘤起始中起关键作用。除了这种经典途径外,AhR 还介导肿瘤促进,最近的证据表明 AhR 也在肿瘤进展中起作用。迄今为止,还没有建立涉及外源物代谢和 AhR 依赖性肿瘤促进和进展的经典途径之间的机制联系。肿瘤促进的一个标志是不平衡的增殖,而肿瘤进展的特征是肿瘤细胞的去分化、运动性增加和转移。肿瘤进展和推测的肿瘤促进是由细胞-细胞接触的丧失触发的。细胞-细胞接触已知是体外和体内增殖、分化和细胞运动的关键调节剂。越来越多的证据表明,AhR 的激活可能导致细胞-细胞接触的失调,从而诱导不平衡的增殖、去分化和增强的运动性。与此一致的是,在一些动物和人类癌症中发现 AhR 表达增加和恶性程度增加。在这里,我们总结了我们目前对涉及细胞-细胞接触失调的非经典 AhR 驱动途径的了解,并讨论了这些数据与肿瘤起始、促进和进展的关系。

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