转录因子Sox2诱导食管癌静止性干细胞向迁移性干细胞转变的作用及机制

Cancer stem cells are the "seeds" of invasion and metastasis. Previously, esophageal cancer stem cells were isolated based on ALDH activity and we found that the invasive and metastatic ability of ALDH1 positive cells is heterogeneous. Only ALDH1 weakly positive cells located in the invasive frontier area, followed by ALDH1 strong positive cells, may be the direct cells responsible for invasion. Moreover, siRNA targeting Sox2 resulted in decreased invasive ability, while increased ALDH1 expression in ALDH1 positive cells. We hypothesize that Sox2 may promote invasion and metastasis by induce ALDH1 strong positive cells switch to ALDH1 weakly positive cells. Therefore, this project intends to use flow cytometry, invasive assay, RNAi and other methods to characterize the ability of self-renewal, invasion and metastasis, tumorigenicity of ALDH1 strong positive cells and ALDH1 weakly positive cells of esophageal cancer cells, then, to study the role and molecular mechanism of Sox2 in ALDH1 strong positive cells switch to ALDH1 weakly positive cells. The results would illustrate the source and generate mechanism of esophageal migratory cancer stem cells, which will provide explanation of heterogeneity of esophageal cancer stem cells in invasion and metastasis as well as development of individual therapeutic methods.

肿瘤干细胞是肿瘤侵袭转移的种子细胞，我们前期以乙醛脱氢酶1 (ALDH1)分离出食管癌干细胞， 发现ALDH1阳性细胞的侵袭转移能力具有异质性，位于侵袭最前沿的细胞为ALDH1弱阳性，紧随其后的细胞为ALDH1强阳性。干扰ALDH1阳性细胞中Sox2可上调ALDH1表达并抑制其侵袭能力。故推测Sox2可能通过抑制ALDH1调控食管癌ALDH1强阳性细胞向弱阳性细胞转变促进食管癌侵袭转移。为验证该假设，我们拟在细胞、动物和组织水平，采用流式分选、免疫组化和RNAi等方法，通过成球、侵袭和成瘤等实验检测ALDH1强阳性和弱阳性细胞的自我更新和侵袭转移能力的差异；观察Sox2调控ALDH1强阳性细胞向弱阳性细胞转变的现象并探讨其分子机制，以期阐明食管癌迁移性干细胞的来源和调控机制，对深入认识肿瘤干细胞侵袭转移异质性和发展食管癌个体化靶向治疗具有重要意义。

侵袭转移是造成肿瘤患者预后不良的重要原因，研究表明肿瘤干细胞是肿瘤侵袭转移的种子细胞，我们前期以乙醛脱氢酶1 (ALDH1)分离出食管癌干细胞，发现ALDH1阳性细胞具有高侵袭转移能力，然而其能力具有异质性，形成机制不清楚。本研究采用流式分选、免疫组化和RNAi等方法，通过成球、侵袭和成瘤等实验1）检测ALDH1强阳性和弱阳性细胞的自我更新和侵袭转移能力的差异，发现ALDH1强阳性的成球能力高于ALDH1弱阳性细胞，而ALDH1强阳性的侵袭能力低于ALDH1弱阳性细胞；2）探索Sox2在调控ALDH1阳性细胞侵袭能力的现象和可能分子机制，发现Sox2可以降低食管癌EC109细胞的ALDH1阳性细胞的成球能力降低，侵袭能力和肺脏转移瘤形成能力；并且ALDH1阳性细胞的Vimentin、Snail、Slug表达下降，E-cadherin表达增加；基质金属蛋白酶MMP2和MMP9表达下降；3）并发现ALDH1的表达和食管鳞癌患者的分化程度、浸润深度，淋巴结转移和TNM分期相关，Sox2表达与分化程度、淋巴结转移和TNM分期相关，并且在食管癌患者中ALDH1和Sox2分子表达具有相关性。本研究发现ALDH1阳性细胞侵袭能力具有异质性，转录因子Sox2调控其高侵袭能力的形成并与上皮间质转化和基质金属蛋白酶表达有关，对认识肿瘤干细胞侵袭转移异质性和发展食管癌个体化靶向治疗具有一定意义。