Notch2/PTEN/Akt通路在食管癌干细胞分化调控中的作用及分子机制研究

Esophageal cancer is one of the most prevalent cancers globally. The lack of effective therapy strategy make it urgent to elucidate the underlying mechanisms of carcinogenesis of esophageal cancer and explore novel targets for prevention and therapy.Notch signaling pathway is one of highly conserved signaling pathways and plays an important role in the tumor cells'self-renewer,differentiation and regulation, malignant proliferation,chemoresistance of tumor initial cells (tumor stem cell,TSC)of many cancers. Based on our previous research, we found that the expression of Notch2,one receptor of Notch signaling pathway were much lower in esophageal cancers tissues than those in adjacent normal tissues.It is also demonstrated that Notch2 was closely associated with the differentiation of tumor cell of esophageal cancer.In addition, notch2 could up regulate the expression of PTEN and make p-Akt low expression. Depending on our experiments,we bulid a bold assumption that Notch2/PTEN/Akt signaling pathway could regulate the diff- erentiation of tumor cells of esophageal cancer and play an important role in the TSC of esophageal cancer. We will build over-expressed Notch2 plasmid and Notch2 silenced one. Then, we invest -igated the role of Notch2 and Notch signaling pathway in the maligant proliferation, invade and migration,self-renewer and differenta- tion, and other biological characteristics in the esophageal tumor cells in vitro and in vivo assays.It is meaningful to observe whether TSC related genes involve in the process of esophageal cancer and its relationship with Notch2;What is the underlying mechanisms of those biological function of Notch signaling pathways in esophageal cancer is also important in our research. Clinical research is another critical part in our study. By detecting a certain number of esophageal cancer samples, analyzing the expression levels of Notch2 and its family,TSC related genes,we try to reveal the role of Notch2 and its signaling pathway in the pathological grade, clincal staging of esophageal cancer patients.We will visit esophageal cancer patients to find out the quality of life after surgery and analyze the relation between genes expression with they prognosis. Desired to investigate the role of Notch2 and its signaling pathway in the esophageal cancer and its molecular mechanisms,we try to clarify the function of Notch2 signaling pathway in tumorigenesis of esophageal cancer and provide a valuable prognosis indicator or even gene target for esophageal cancer treatment.

食管癌是常见的恶性肿瘤之一，我国是食管癌的绝对高发地区。Notch2分子在不同肿瘤中既能发挥促癌作用，又能抑制肿瘤生长，但机制不清。本课题组前期检测大量临床食管癌样本发现Notch2在癌组织存在异常低表达，并与食管癌分化、患者预后呈正相关，而高表达Notch2促进PTEN表达，抑制Akt通路。为了进一步阐明Notch2/PETN/Akt通路在食管癌恶性表型抑制及干细胞分化中的作用机制，本研究建立Notch2食管癌稳定细胞系及小鼠种植模型，体内外实验观察其抑制食管癌细胞恶性表型作用，利用“染色+流式分选”对比研究Notch2促进食管癌干细胞分化，并阐明Notch2/PTEN/Akt通路在食管癌恶性表型及干细胞分化调控具体方式，为靶向治疗提供依据；通过大规模食管癌临床样本检测，系统分析Notch2在食管癌进展中的动态变化及其与食管癌患者预后的关系，探讨Notch2在食管癌患者预后判断中的价值。

食管癌在中国属于高发恶性肿瘤，总体治疗效果不佳。相关基础研究缺乏，因此本课题以Notch2j通路为出发点研究其在食管癌的恶性表型、肿瘤干细胞相关基因调控中作用和机制进行立项。本课题按照计划首先通过检测多个食管癌细胞系和正常食管内皮细胞发现Notch2在食管癌细胞中本底表达情况，之后建立稳定表达细胞系，进行细胞生物学实验研究其在食管癌中的生物学功能，通过检测干细胞相关基因的表达，了解Notch2在食管癌干细胞相关基因中的作用，在机制探索方面除了常规检测相关通路基因观察作用方式，还进行深层次的泛素化研究发现了一个在Notch2通路食管癌中降解机制发挥重要功能的基因，进一步研究两者之间关系，揭示了在食管癌中Notch2通路存在一种新的作用机制。临床方面，通过对大量食管癌标本检测揭示了Notch2基因在食管癌中为高表达情况，DTX3基因作为泛素化基因在食管癌中低表达情况，本研究为食管癌基础机制研究提供实验支撑，为将来食管癌的靶向治疗研究提供可靠实验数据。