MDC1募集MBD1/SIRT1调控DNA损伤修复影响胰腺癌放化疗抵抗的实验研究

It is well acknowledged that DNA damage repair and chemo-radioresistance are closely related in pancreatic cancer. Previously, we had demonstrated that MBD1 was involved in DNA damage repair and chemo-radioresistance by means of a high-throughput proteomic filtering technology. With further research, we found that MBD1 may facilitate NBS1 phosphorylation after recruited by MDC1, which contributed to the modulation of DNA damage repair and the chemo-radioresistance afterwards. Based on our previous study about the protein interactions, we speculated that SIRT1 may have an important role as a connected molecular between MBD1 and phosphorylated NBS1. So we suggest that there is a new molecular mechanism as an axis of MDC1-MBD1/SIRT1-NBS1 to take effect and we are going to carry out some researches on this functional axis as below: 1. Analyze the connection between the MDC1, MBD1/SIRT1 and NBS1 both structurally and functionally in pancreatic cancer for the confirmation of this axis. 2. Determinate the expression of these molecular in clinical specimens to investigate the correlation between this axis and chemo-radioresistance in pancreatic cancer. 3. Disturb this functional axis by some in vitro and in vivo assays for further validation that it can effectively predict the chemo-radioresistance and serve as a potential therapeutic target in pancreatic cancer.

DNA损伤修复与胰腺癌放化疗抵抗密切相关。我们前期通过高通量蛋白质组学筛选技术发现，MBD1与DNA损伤修复有关；深入研究证实，MBD1能被MDC1募集，促进NBS1的磷酸化，进而调控DNA损伤修复及放化疗抵抗；基于蛋白-蛋白相互作用分析及前期研究提示，我们又推测SIRT1是MBD1促进NBS1磷酸化的中间衔接分子，由此提出"MDC1-MBD1/SIRT1-NBS1"功能轴这一新的分子机制。本课题拟在前期研究的基础上，进一步围绕此功能轴开展以下研究：①分析胰腺癌细胞中MDC1、MBD1/SIRT1、NBS1在结构和功能上的联系，对此功能轴进行验证；②在胰腺癌临床样本中检测MDC1、MBD1/SIRT1、NBS1的表达，探讨此功能轴与胰腺癌放化疗抵抗的相关性；③通过体内、体外实验，干预此功能轴，明确其对胰腺癌DNA损伤修复及放化疗抵抗的影响，为临床上胰腺癌放化疗抵抗提供干预和预测的潜在靶点。

胰腺癌早期诊断困难，手术切除率低，手术切除后又极其易转移复发，因此胰腺癌的化疗、放疗为主的综合治疗是胰腺癌治疗的主要组成部分。然而由于胰腺癌细胞本身就存在对放疗和化疗抵抗的生物学特性，即使采用化疗、放疗也难以达到很好的预期效果。因此深入了解胰腺癌化疗、放疗的分子机制，并寻求相应策略，可改善胰腺癌不良预后。本项目在前期的研究基础上，提出了MBD1、MDC1、NBS1、SIRT1在胰腺癌中不良预后、化疗、放疗耐药方面的作用，并对其中机制进行了深入探讨。在项目资助下，发现了指标分子在胰腺癌的不良预后、胰腺癌吉西他滨耐药方面发挥着重要的作用。首先针对MBD1进行深入探讨，发现了MBD1的相互作用蛋白cMyc，并对机制进行深入解析，发现了Kras/cMyc通路在胰腺癌发生、发展、侵袭转移、代谢异常、氧化还原环境失衡方面的重要作用，在项目的直接资助下发表了《Cell Research》、《Clinical Cancer Research》、《Molecular Cancer Research》、《Cancer Letters》、《BBA Reviews on Cancer》、《Current Molecular Medicine》等多篇SCI论文。针对MDC1在胰腺癌中的作用，项目组成员进行了深入的探讨，证实了MDC1在胰腺癌中的表达与胰腺癌预后的关系，发表了《Oncogene》文章。针对NBS1、SIRT1，进行研究，发现了NBS1、SIRT1的表达与胰腺癌不良预后、吉西他滨化疗耐药的关系，取得了初步数据。总结整个项目，在项目的资助下，完善了MBD1、MDC1、NBS1、SIRT1等相关分子在胰腺癌发生、发展、侵袭转移、化疗耐药中的作用，并深入研究，发现了其中的分子机制，为逆转胰腺癌以吉西他滨为主的化疗耐药、改善不良预后提供了预测指标和干预靶点。