组蛋白去乙酰化酶抑制剂联合自噬增加肺癌放疗敏感性的实验研究

肿瘤细胞核内DNA双链断裂（DSBs）修复是放疗抵抗的重要原因。最近研究及我们的工作发现，自噬可降解胞质中DSBs修复蛋白增加肿瘤放疗敏感性，但作用有限。最新研究发现，组蛋白去乙酰化酶抑制剂（HDACi）可促使酵母细胞核内DSBs修复蛋白乙酰化，移位至胞质中被自噬降解，抑制DNA DSBs修复，但在肿瘤细胞中未见报道。我们前期工作证实HDACi联合上调自噬可减少胞核中DSBs修复蛋白，增加A549细胞放疗敏感性。故推测HDACi可使核内DSBs修复蛋白乙酰化并移位到胞质，被自噬降解，增加肺癌放疗敏感性。因此，本项目拟将HDACi联合自噬，观察其增加裸鼠肺癌皮下移植瘤模型放疗敏感性的作用，同时观察A549细胞质中乙酰化DSBs修复蛋白的移位及与自噬小体的共定位，探讨其增加肺癌放疗敏感性的机制；并通过临床肺癌组织标本分析自噬及乙酰化水平与放疗敏感性及预后的关系，为肺癌的放射治疗提供理论依据。

Repairing of DNA double-strand break (DSBs) in the nucleus of tumour cells is main reason for resistance in radiotherapy. Recent studies and our research showed that autophagy could degrade the repairing protein of DSBs and improved the sensitivity of radiotherapy in tumour cells, but the effects were limited. Recent studies also demonstrated that histone deacetylase inhibitor (HDACi) could make the repairing protein of DSBs acetylased, relocated and degraded by autophagy, and subsequently inhibit the repairing of DNA DSBs in yeast cells. However, these effects have never been reported in the tumour cells. We also confirmed that HDACi combined with autophagy decreased the repairing protein of DSBs in the nucleus and increased the sensitivity of radiotherapy in A549 cells. We speculated that HDACi could make the repairing protein of DSBs acetylased, relocated and degraded by autophagy, and subsequently increase the sensitivity of radiotherapy in lung cancer . Therefore, in this project we will observe the sensitivity of radiotherapy in the lung cancer transplanted naked mice using HDACi combined with autophagy, investigate the acetylasation of repairing protein of DSBs, migration and co-location of autophagosome in A549 cells, and explore the mechanism of sensitivity of radiotherapy in lung cancer. We also analyse the correlation between the levels of autophagy and acetylasation, of the samples in lung cancers and the sensitivity and outcome, and provide the evidence for radiotherapy of lung cancer.