MTDH regulates Fanconi anemia repair pathway to mediate drug resistance

描述（由申请人提供）：细胞耐药是实体瘤治疗失败的主要原因之一，因此强调需要识别驱动侵袭性表型的新因素。metadherin （MTDH，也称为AEG-1和LYRIC）的过表达已在许多实体瘤中得到证实，并与不良预后相关。此外，MTDH过表达与转移和对治疗的抵抗有关，这是侵袭性癌症的两个重要标志。我们最近发现MTDH作为RNA结合蛋白改变多种mrna的翻译，从而确定了MTDH在翻译后基因表达中的潜在作用。这些mrna包括范可尼贫血（FA）途径中的几种DNA修复蛋白。我们在这个应用程序的目的是确定MTDH调控DNA修复的作用在耐药治疗。该项目的基本原理是，由于MTDH在多种癌症类型中高度表达，并有助于抗性表型的出现，因此对MTDH功能的机制见解将为开发MTDH途径靶向治疗提供强有力的科学框架。为了验证我们的中心假设，我们提出了三个具体目标：在目标1中，我们将确定MTDH与特定mrna关联改变DNA损伤反应途径的机制。利用MTDH缺失的癌细胞系和MTDH-/-小鼠胚胎成纤维细胞，我们将研究MTDH在mRNA代谢中的作用以及对Rad18、FANCI、FANCD2等DNA修复蛋白翻译的控制。我们将扩展研究，以确定mRNA模拟物敲低或破坏MTDH:mRNA复合体是否足以干扰FA通路基因的MTDH翻译调节。在Aim 2中，我们将通过靶向MTDH和DNA修复途径来克服顺铂耐药。我们将评估靶向MTDH和FA DNA修复途径是否可以通过破坏细胞对DNA损伤的反应来提高顺铂的治疗效果。在Aim 3中，我们将确定MTDH表达和FA通路激活对癌症中icl诱导药物耐药性的影响。研究将包括：1)异种移植实验，使用我们的活肿瘤库中特征明确的人子宫内膜肿瘤；2)应用icl诱导药物治疗86例晚期子宫内膜癌患者FFPE肿瘤组织中MTDH和FA通路的免疫组化分析。在本次研究成功完成后，我们期望通过MTDH对mRNA稳定性的调控和FA通路蛋白的翻译来了解MTDH的病理功能。这些结果有望产生重要的积极影响，因为它们将为MTDH过表达与治疗耐药的相关性提供强有力的机制基础，并为未来MTDH靶向治疗的发展奠定基础。

DESCRIPTION (provided by applicant): Cellular resistance is one of the major causes of therapeutic failure for solid tumors, thus highlighting the need to identify novel factors driving aggressive phenotypes. Overexpression of metadherin (MTDH, also known as AEG-1 and LYRIC) has been documented in numerous solid tumors to date and correlates with poor prognosis. Moreover, MTDH overexpression has been implicated in metastasis and resistance to therapy, two important hallmarks of an aggressive cancer. We recently made the important discovery that MTDH acts as an RNA binding protein to alter translation of multiple mRNAs, thus identifying a potential role for MTDH in post- translational gene expression. These mRNAs include several DNA repair proteins in the Fanconi anemia (FA) pathway. Our objective in this application is to determine the role of MTDH regulation of DNA repair in resistance to therapy. The rationale for this project is that because MTDH is highly expressed in multiple cancer types and contributes to the emergence of a resistant phenotype, mechanistic insights into how MTDH functions will offer a strong scientific framework whereby MTDH pathway targeted therapies can be developed. To test our central hypothesis, we propose three specific aims: In Aim 1, we will identify mechanisms by which MTDH association with specific mRNAs alters the DNA damage response pathway. Using MTDH-deficient cancer cell lines and MTDH-/- mouse embryonic fibroblasts, we will study the role of MTDH in mRNA metabolism and control of translation of Rad18, FANCI, FANCD2 and other DNA repair proteins. We will extend studies to determine if MTDH knockdown or disruption the MTDH:mRNA complex by mRNA mimetics are sufficient to perturb MTDH translational regulation of FA pathway genes. In Aim 2, we will overcome resistance to cisplatin by targeting MTDH and the DNA repair pathway. We will evaluate whether targeting MTDH and the FA DNA repair pathway can increase the therapeutic efficacy of cisplatin via disruption of the cellular response to DNA damage. In Aim 3, we will determine the effect of MTDH expression and FA pathway activation on resistance to ICL-inducing agents in cancer. Studies will include 1) xenograft experiments using well-characterized human endometrial tumors from our viable tumor bank; and 2) immunohistochemical analysis of the MTDH and FA pathway in FFPE tumor tissues from 86 advanced endometrial cancer patients treated with ICL-inducing agents. Upon the successful completion of the proposed research, it is our expectation that we will understand the pathological function of MTDH through its regulation of mRNA stability and translation of FA pathway proteins. These results are expected to have an important positive impact because they will provide a strong mechanistic basis for the correlation of MTDH overexpression with therapeutic resistance and serve as a foundation for the future development of MTDH-targeted therapies.