低水平雌激素促胃癌干细胞自我更新及生长分化的调控机制

In recent years, evidence suggests that estrogens (E2) play an important role in gastric cancer, but the mechanism is unknown. Our data show the low level of E2 promotes gastric cancer cell growth and invasion. It is new found that the low level E2 can promote gastric cancer cells spheroid colony formation, with gastric cancer stem cell phenotype makers and epithelial cells and mesenchymal cell markers presenting and the transplanted tumor volume significantly greater than the control group in nude mice. When these cells were cultured in convention, the spheroid colony and gastric cancer stem cell markers disappeared. The above experiment was repeat with ER-α36 low expression and ER-α36 high expression of recombinant human gastric cancer cell, the former almost do not form spherical colony, the latter vice versa. Giving the low concentration of E2 to the high ER-α36 expression of the gastric cancer cell, the number of CD44 + / CD24-/low was significantly increased comparing to that is given to without E2 or with high concentrations of E2. The mechanism is unknown. Accordingly, we propose the scientific idea that biological effects of estrogen and ER-alpha play an important role in the development of gastric cancer, lower estrogen levels contribute to gastric cancer stem cell self-renewal, proliferation and differentiation. The project intends to argument the above assumption adopting the classic method of tumor stem-cell research, and the results are expected to make a breakthrough in the basic theory of the gastric cancer study.

近年的证据显示，雌激素（E2）在胃癌中具有重要作用，但作用机制不明。我们在低水平E2促胃癌细胞生长与侵袭的研究中，新发现低水平E2可促胃癌细胞形成球形集落，并具有胃癌干细胞表型标志、上皮细胞和间叶细胞标志，裸鼠移植瘤体积明显大于对照组的特点。将上述细胞转至常规培养，球形集落及胃癌干细胞标志消失。对ER-α36沉默和高表达的重组胃癌细胞重复上述实验，前者几乎不形成球形集落，后者反之。给予ER-α36高表达的胃癌细胞低浓度E2重复， CD44+/CD24-/low细胞数量较不给于E2和高浓度E2组明显增多，机制不详。据此我们提出：雌激素及ER-α的生物学效应在胃癌的发生发展中发挥重要作用,低水平雌激素促胃癌干细胞自我更新、生长与分化是重要途径之一的科学设想。本项目拟将采用肿瘤干细胞研究的经典方法论证推论，其成果有望在雌激素与胃癌的基础理论方面取得突破。

本项研究在成功构建胃癌肿瘤细胞球(肿瘤干细胞)并鉴定的基础上，发现不同浓度雌激素对胃癌肿瘤干细胞形成、胃粘膜细胞软琼脂集落形成能力以及胃癌细胞上皮间质转化的影响不尽相同。生理性浓度雌激素（低浓度雌激素）促进肿瘤球细胞的形成、肿瘤集落的形成和胃癌细胞上皮间质转化，而生理性及治疗性高浓度雌激素（高浓度雌激素）抑制肿瘤球细胞的形成、肿瘤集落的形成以及胃癌细胞上皮间质转化。在本研究中进一步发现ER-α36-c-src信号通路与胃癌细胞增殖有关、雌激素通过ER-α36信号通路诱导了Cyclin D1的表达、ER-α36促进了裸鼠成瘤、ER-α36与EGFR通过c-src相互作用共同参与雌激素双相信号通路的形成、ER-α36参与形成雌激素双相信号通路、ER-α36参与促细胞增殖的效应可以通过Klf4等转录因子的激活而实现，17β-estradiol和Tamoxifen通过ER-α36信号通路对胃癌细胞增殖和凋亡的影响。本项目从分子、细胞、人体及动物实验（部分结果）多层面获得了ER-α36与胃癌的干细胞形成、胃癌细胞增殖、侵袭、转移及与雌激素双相调节的关系及其机理，为胃癌的防治及进行下一步研究打下了坚实的基础。已在国内外期刊上发表论文多篇，并在研究过程中申请到国家专利1项，国家实用新型专利（解决实验过程中的问题）2项，其中1项正在申请转为国家专利。