The role of the RO60 (TROVE2) autoantigen in modulating cell-cycle progression, apoptosis and chemo-resistance in cancer cells

RO 60（TROVE 2）蛋白是高度保守的RNA结合蛋白，在风湿性疾病患者中被鉴定为自身抗原。从细菌到人，RO 60被认为是细胞应激反应的关键调节剂，并被证明在紫外线照射后促进细胞存活。到目前为止，这种保护作用主要归因于它们在调节错误折叠的非编码RNA，特别是核糖体5S和U2 RNA的螯合和降解中的功能。RO 60在调节RNA监视中的作用与其参与风湿性疾病的关系仍然知之甚少。此外，RO 60是否以及如何调节肿瘤细胞的功能仍然是一个谜，在初步研究中，我们观察到RO 60拮抗p53依赖性的CDKN 1A（p21）上调，并增强肿瘤衍生或转化细胞的药物抗性和UV抗性。这种调节作用似乎是通过RO 60对ATR-CK 1（ATR：共济失调毛细血管扩张和Rad 3相关蛋白; CK 1：检查点激酶1）（ATR：共济失调毛细血管扩张和Rad 3相关蛋白; CK 1：检查点激酶1）信号传导的直接控制来促进的，并可能涉及与非编码Y-RNA的结合改变。在以前的研究中，我们证明了这些来自小RNP样复合物的非编码RNA与RO 60和其他RNA结合蛋白如IGF 2BP [Köhn et al.，RNA 2010]。支持R 060的保护作用，我们发现R 060的敲低降低了细胞活力并使肿瘤衍生细胞对药物敏感，特别是吉西他滨，吉西他滨是一种经常使用的诱导DNA损伤和复制阻断的化疗剂。基于我们的初步研究，我们假设RO 60是细胞对DNA损伤的反应的关键调节剂，并支持肿瘤细胞的药物/化学抗性。通过所提出的项目，我们旨在表征RO 60如何调节肿瘤细胞的DNA损伤诱导的应激反应。此外，我们打算评估特定RO 60亚型的耗竭是否使癌源性细胞对化疗药物敏感，以及这是如何通过p53状态调节的。我们希望我们的研究将为RO 60在肿瘤细胞中的作用提供新的见解，并将允许评估这个RNA结合蛋白家族作为未来癌症治疗的候选靶点。

The RO60 (TROVE2) proteins are highly conserved RNA-binding proteins which were identified as autoantigenes in patients with rheumatic diseases. From bacteria to men, RO60s were suggested as key modulators of the cellular stress response and were shown to promote cell survival upon UV-irradiation. So far, this protective role was mainly attributed to their functions in regulating the sequestering and degradation of misfolded non-coding RNAs, in particular the ribosomal 5S and U2 RNAs. How the proposed role of RO60s in regulating RNA-surveillance correlates with their involvement in rheumatic diseases remains poorly understood. Moreover, it remains elusive whether and how RO60s modulate tumor cell functions.In preliminary studies we observed that RO60s antagonize the p53-dependent upregulation of CDKN1A (p21) and enhance the drug- as well as UV-resistance of tumor-derived or transformed cells. This regulatory role appears to be facilitated by RO60-directed control of ATR-CK1 (ATR: ataxia telangiectasia and Rad3-related protein; CK1: check point kinase 1) (ATR: ataxia telangiectasia and Rad3-related protein; CK1: check point kinase 1) signaling and presumably involves altered binding to non-coding Y-RNAs. In previous studies, we demonstrated that these non-coding RNAs from small RNP-like complexes with RO60s and other RNA-binding proteins like IGF2BPs [Köhn et al., RNA 2010]. Supporting the protective role of RO60s, we found that the knockdown of RO60s reduced cell viability and sensitized tumor-derived cells to drugs, in particular gemcitabine, a frequently used chemotherapeutic which induces DNA-damage and replication block. Based on our preliminary studies we hypothesize that RO60s are key modulators of the cellular response to DNA-damage and support drug-/chemo-resistance of tumor cells. With the projects proposed we aim at characterizing how RO60s modulate the DNA-damage induced stress-response of tumor cells. Moreover, we intend to evaluate whether the depletion of specific RO60 isoforms sensitizes cancer-derived cells to chemotherapeutics and how this is modulated by p53-status. We expect that our studies will provide novel insights into the role of RO60s in tumor cells and will allow evaluating this family of RNA-binding proteins as future candidate targets for cancer treatment.