p53基因在TSA诱导结肠癌细胞内质网应激反应中的作用及分子机制研究

Colon cancer is a common malignant tumor worldwide. The morbidity and mortality of colon cancer is among the top five of all tumors in developed countries. In China, the morbidity and mortality of colon cancer is in an upward trend, which is expected to approach the level of Europe and the United States. As a noval kind of antitumor drug for chemotherapy, TSA is a classic inhibitor of histone deacetylases (HDAC) with potential perspective in clinical application. However, its molecular mechanism is far from being elucidated. In our previous work, TSA could induce gene expression of ER stress marker such as GRP78 and GRP94 at protein and mRNA level in p53+/+ HCT116 cells. Also, by using RT-PCR and luciferase reporter assay, the splicing form of XBP1 under the condition of ER stress gene was observed. However, this phonotype was not detected in p53-/- HT29 cells. Further studies showed efficiently knockdown of p53 resulted in attenuated ER stress markers by TSA, and reduced sensitivity of HCT116 cells to TSA. These data suggest that TSA can induce ER stress in p53 wild type of colon cancer, and p53 plays an important role in this cellular process. So, in current project we will further investigate the phenomena both in vitro and in vivo models, and explore the molecular mechanism involved and the biologic significance of ER stress in cancer chemotherapy. This project helps to discover the new molecular mechanism of TSA and deeply understand its significance of ER stress, which will benefit the clinical application of TSA.

结肠癌为我国多发的消化道恶性肿瘤，严重威胁人类健康。作为一类潜在的抗肿瘤药物，组蛋白去乙酰化酶抑制剂(如TSA)具有较好的应用前景，然而其分子机制远未完全阐明。我们前期研究发现：TSA可以诱导p53+/+的HCT116细胞内质网应激反应标志分子表达上调，以及XBP1分子的差异剪接，而在p53-/-的HT29细胞中却检测不到类似表现；进一步研究显示干扰p53基因表达可显著减轻TSA诱导HCT116细胞的内质网应激反应，降低细胞对TSA的敏感性。这些结果提示：TSA可以引起结肠癌细胞的内质网应激反应，且p53基因参与了该过程。因此，本项目将在离体的细胞水平和荷瘤动物模型上深入观察TSA诱导内质网应激反应现象，探讨其信号途径，阐明p53基因在其中的作用和可能的分子机制，并试图回答内质网应激在肿瘤治疗的生物学意义。本研究可深入揭示TSA作用于肿瘤细胞的分子机制，对临床肿瘤的化疗具有重要指导意义。

结肠癌为我国多发的消化道恶性肿瘤，严重威胁人类健康。作为一类潜在的抗肿瘤药物，组蛋白去乙酰化酶抑制剂(如TSA)具有较好的应用前景，然而其分子机制远未完全阐明。经过本课题组研究发现：组蛋白去乙酰化酶抑制剂TSA可以诱导p53野生型的HCT116细胞出现内质网应激反应，反映在GRP94、GRP78等标志分子表达上调，以及XBP1分子的差异剪接。药物所引物的内质网应激反应依赖于p53基因的存在，因为在p53突变的HT29细胞和p53敲除的HCT116细胞中却检测不到类似表现。进一步对比TSA对p53 WT和KO的HCT116的杀伤效应发现：p53 WT的细胞对药物更加敏感，表现在药物处理后细胞增殖显著降低、细胞凋亡明显增加；且干扰p53 WTHCT116细胞有相类似表现。分析信号通路发现：TSA诱导的内质网应激反应相关的途径有IRE1和PERK通路。本研究部分揭示TSA作用于肿瘤细胞的分子机制，对临床肿瘤的化疗具有一定指导意义。