Epithelial-mesenchymal transition regulators in radioresistance and DNA repair

描述(由申请人提供)： 放射治疗是利用电离辐射对DNA造成损伤的治疗方法，在癌症治疗中发挥着重要作用。DNA损伤被细胞周期检查点识别，导致DNA损伤修复途径的激活。最近，肿瘤干细胞被证明通过激活DNA损伤反应来促进肿瘤的辐射抵抗。此外，一种被称为上皮-间充质转化(EMT)的跨分化过程被认为可以促进转移并产生干细胞样细胞。除了与肿瘤的进展和转移有关外，EMT还被证明与肿瘤干细胞的特性有关，包括化疗耐药和辐射耐药。然而，目前尚不清楚哪些EMT监管机构在这些特性中发挥了因果作用。我们和其他人之前已经发现了microRNA介导的转移和EMT的调节。此外，我们提供了原则证据证明，在临床前模型中，治疗性沉默有利于转移的microRNA可以阻止转移。在这项研究中，我们打算寻找代表辐射抗性和DNA损伤修复的新的调节者的EMT调节转录因子和microRNAs，确定它们的作用机制和表达调控，并探索它们作为新的癌症生物标志物和治疗靶点的潜在用途。在初步研究中，我们发现最近报道的两个EMT调节因子ZEB1和miR-205相互负向调节，在调节肿瘤细胞的放射敏感性方面扮演相反的角色。此外，我们的数据表明，ATM信号在稳定ZEB1中发挥作用，ZEB1在促进去泛素化介导的CHK1稳定中发挥作用，CHK1是细胞周期检查点控制和同源重组介导的DNA损伤修复所必需的蛋白激酶。在拟议的未来研究中，我们将：1)研究ZEB1和miR-205在肿瘤辐射耐药性和肿瘤干细胞特性中的作用；2)确定ZEB1调节辐射敏感性和DNA损伤反应的机制；3)确定ZEB1如何在辐射和DNA损伤反应中上调；4)研究ZEB1和miR-205在人类肿瘤中的参与及其治疗潜力。从这些研究中获得的知识将为特定的EMT调节剂如何促进肿瘤辐射抵抗和DNA损伤修复提供新的见解，并可能具有重要的临床意义。

DESCRIPTION (provided by applicant): Radiation therapy, the therapeutic use of ionizing radiation to induce damage to the DNA, plays an important role in cancer management. DNA lesions are recognized by cell cycle checkpoints, leading to activation of DNA damage repair pathways. Recently, cancer stem cells have been shown to promote tumor radioresistance through activation of DNA damage response. In addition, a trans-differentiation process, termed epithelial-mesenchymal transition (EMT), is thought to promote metastasis and generate stem-like cells. Besides its implication in tumor progression and metastasis, EMT has been shown to be associated with characteristics of cancer stem cells, including chemoresistance and radioresistance. However, it is not clear which EMT regulators play causal roles in these properties. We and others have previously uncovered microRNA-mediated regulation of metastasis and EMT. Moreover, we provided proof-of-principle evidence that therapeutic silencing of a pro-metastatic microRNA can block metastasis in a preclinical model. In this research, we intend to seek EMT-regulating transcription factors and microRNAs that represent novel regulators of radioresistance and DNA damage repair, determine their mechanism of action and regulation of expression, and explore their potential use as new cancer biomarkers and therapeutic targets. In preliminary studies, we found that two recently reported EMT regulators, ZEB1 and miR-205, negatively regulate each other and play opposing roles in modulating radiosensitivity of tumor cells. Furthermore, our data point to a role of ATM signaling in stabilizing ZEB1 and a role of ZEB1 in promoting deubiquitination-mediated stabilization of CHK1, a protein kinase that is required for cell cycle checkpoint control and homologous recombination-mediated DNA damage repair. In proposed future studies, we will: 1) investigate the role of ZEB1 and miR-205 in tumor radioresistance and cancer stem cell properties; 2) identify the mechanism by which ZEB1 regulates radiosensitivity and DNA damage response; 3) determine how ZEB1 is upregulated in response to radiation and DNA damage; 4) study the involvement of ZEB1 and miR-205 in human tumors and the therapeutic potential. The knowledge gained from these studies will provide new insights into how specific EMT regulators contribute to tumor radioresistance and DNA damage repair and may have significant clinical implications.