Regulation of homologous recombination and cancer cell response to chemoradiotherapy

 描述(由申请人提供)：许多研究表明，DNA修复因子的过度表达可能导致放化疗耐药。因此，研究该通路对肿瘤的发病机制和肿瘤治疗具有重要意义。我们发现UCHL3，一种脱泛素酶，在乳腺癌中过表达。此外，UCHL3的高表达与乳腺癌患者的预后不良相关。然而，由于UCHL3的细胞功能仍不清楚，目前尚不清楚UCHL3是否与临床表型有关。在这里，我们第一次展示了UCHL3参与DNA修复。我们发现UCHL3与RAD51相互作用并使RAD51去泛素化，而不影响RAD51的水平。UCHL3本身在DNA损伤后被磷酸化，并被招募来双链断裂。此外，UCHL3对于RAD51的招募到双链断裂和同源重组是重要的。下调UCHL3使乳腺癌细胞对辐射和PARP抑制剂敏感，而过度表达UCHL3使乳腺癌细胞对这些治疗产生抗药性。根据这些初步数据，我们假设UCHL3是DNA修复中的一个新因子。UCHL3去泛素化RAD51，促进RAD51功能和同源重组。UCHL3的增加通过增强DNA修复来提高对放射和化疗的抵抗力。在本申请中，我们将进一步探索UCHL3是如何调控RAD51的，以及UCHL3本身是如何调控的。我们还将使用临床相关的模型来测试UCHL3在放化疗耐药中的作用。我们的具体目标是：1.研究UCHL3对RAD51的调控；2.研究UCHL3的调控；3.研究UCHL3在乳腺癌治疗中的作用。我们的研究将揭示UCHL3在DNA修复和对放化疗反应中的新功能。此外，它还将揭示一个新的治疗靶点，通过靶向UCHL3-RAD51途径来敏化乳腺癌细胞，特别是那些高表达UCHL3的细胞。

 DESCRIPTION (provided by applicant): Many studies suggest that overexpression of DNA repair factors could contribute to resistance to radiochemotherapy. Therefore, studying this pathway has important implications in cancer pathogenesis and cancer therapy. We found that UCHL3, a deubiquitinase, is overexpressed in breast cancer. In addition, increased expression of UCHL3 correlates with poor prognosis for breast cancer patients. However, whether or not UCHL3 casually contributes to clinical phenotypes is unclear, because the cellular function of UCHL3 remains unclear. Here we show for the first time that UCHL3 is involved in DNA repair. We found that UCHL3 interacts Rad51 and deubiquitinates Rad51 without affecting Rad51 levels. UCHL3 itself is phosphorylated following DNA damage and is recruited to double strand breaks. In addition, UCHL3 is important for the recruitment of Rad51 to double strand breaks and homologous recombination. Downregulating UCHL3 sensitizes breast cancer cells to radiation and PARP inhibitors, while overexpressing UCHL3 renders breast cancer cells resistant to these treatments. Based on these Preliminary Data, we hypothesize that UCHL3 is a new factor in DNA repair. UCHL3 deubiquitinates Rad51 and promotes Rad51 function and homologous recombination. Increased UCHL3 contributes to resistance to radiation and chemotherapy by enhancing DNA repair. In this application, we will further explore how UCHL3 regulates Rad51 and how UCHL3 itself is regulated. We will also test the role of UCHL3 in radiochemoresistance using clinically relevant models. Our Specific Aims are: 1. Investigate the regulation of Rad51 by UCHL3; 2. Study the regulation of UCHL3; 3. Investigate the role of UCHL3 in breast cancer therapy. Our studies will reveal a novel function of UCHL3 in DNA repair and response to radiation and chemotherapy. In addition, it will reveal a new therapeutic target in sensitizing breast cancer cells, especially those overexpressing UCHL3, by targeting the UCHL3-Rad51 pathway.