雄激素及雄激素受体促进乳腺癌发展与转移的机制研究

发布时间：2018-04-17 15:36

本文选题：雄激素 + 雄激素受体　；参考：《东北师范大学》2017年博士论文

【摘要】：尽管雄激素通常被视为是男性激素,但正常女性体内同样可以检测到相当浓度的,具有生理意义的雄激素水平。数项临床研究均证实,不论是绝经前女性还是绝经后女性,体内雄激素水平的异常升高均伴随着罹患乳腺癌风险的增加。而作为雄激素的受体,雄激素受体(AR)却在临床上被认为是一个良好的预后指标,乳腺癌中的AR阳性往往伴随着更长的无复发期,无转移期以及更长的个体存活时间,较小的肿瘤大小,更低的组织学分级。这两种结论的存在,显然是矛盾的。有些学者提出了一种“代谢转化”理论来解释这个矛盾,即,雄激素在体内通过代谢作用转化为雌激素,进而激活了雌激素受体相关通路,进而促进了乳腺癌的发展。此种理论虽然存在理论上的可能,却一直没有相关的临床统计支持,亦或是分子水平的实验数据支持或是反对。本实验深入探讨了雄激素在乳腺癌细胞中的作用及分子机制,确定了雄激素并不会显著影响乳腺癌细胞的增殖和细胞周期,但会增强乳腺癌细胞的迁移和侵袭能力。而且通过在AR阳性ER阴性的细胞T47D细胞中的验证,证明雄激素的此种促癌作用是通过AR的激活,而非ER的激活而实现的。进一步的分子和细胞生物学实验证实,雄激素能促进乳腺癌细胞发生上皮间质转化(EMT),并继而增强细胞的迁移和侵袭能力。随后的实验证实雄,激素激活AR后,促进AR二聚化入核,激活靶基因E-cadherin,并抑制靶基因vimentin。我们分析后发现,E-cadherin启动子和vimentin启动子上均存在可能的AR应答元件(ARE),染色质免疫共沉淀实验证明AR/LSD1组成的复合物结合到E-cadherin和vimentin启动子上的ARE并发挥去甲基化活性,调控基因转录。具体来说,在E-cadherin启动子上,AR/LSD1复合物去除激活基因表达的表观修饰H3K4的甲基化,进而抑制基因表达;而在vimentin启动子上,AR/LSD1会导致抑制性表观修饰H3K9的甲基化减弱,进而激活基因的表达。干涉掉AR或LSD1,亦或是LSD1抑制剂的使用,会使这种去甲基化得到回复,进而证明了此过程中AR和LSD1都是不可或缺。活体实验中,雄激素处理并不会对裸鼠原位注射的乳腺癌细胞的成瘤的大小产生明显的影响,但会显著增强乳腺癌细胞的肺转移和血管壁穿透能力,而干涉AR或LSD1的表达后,会减弱此种肺转移的发生,证明雄激素,AR以及LSD1在此过程中确实发挥了重要作用。临床统计分析显示,AR和LSD1的表达,对乳腺癌患者的生存期有着一定的影响。进一步分析AR的核质分布,则会发现,核质分布差异越明显(我们把这一现象作为雄激素水平较高的一种结果),患者的临床分级与预后则越差。综上所述,我们发现了一条“雄激素-AR/LSD1-乳腺癌发展和转移”的分子路径,此研究提示了女性体内激素平衡的重要性,而我们提出的AR-D值的建立有可能成为临床诊断分析的一个新指标。
[Abstract]:Although androgens are commonly regarded as male hormones, normal women can also detect significant levels of androgen at physiological levels.Several clinical studies have confirmed that elevated androgen levels in both premenopausal and postmenopausal women are associated with an increased risk of breast cancer.As a receptor of androgen, androgen receptor ARA is considered to be a good prognostic marker in clinical practice. AR-positive in breast cancer is associated with longer recurrence, metastasis and longer survival time.Smaller tumor size, lower histological grade.The existence of these two conclusions is obviously contradictory.Some scholars have proposed a "metabolic transformation" theory to explain this contradiction, that is, androgen is transformed into estrogen through metabolism in vivo, which activates the estrogen receptor related pathway and promotes the development of breast cancer.Although there is a theoretical possibility in this theory, there has been no related clinical statistical support, or the molecular level of experimental data support or opposition.In this study, we studied the role and molecular mechanism of androgen in breast cancer cells. It was concluded that androgen did not significantly affect the proliferation and cell cycle of breast cancer cells, but could enhance the migration and invasion of breast cancer cells.Furthermore, it was proved that the carcinogenic effect of androgen was mediated by the activation of AR, not ER, by the verification in T47D cells with AR positive and ER negative.Further molecular and cellular biological experiments have demonstrated that androgen can promote the development of epithelial mesenchymal transformation of breast cancer cells and then enhance the migration and invasion of breast cancer cells.The subsequent experiments confirmed that androgen activates AR, promotes AR dimerization into nucleus, activates target gene E-cadherin, and inhibits target gene vimentin.We found that both E-cadherin promoter and vimentin promoter had a possible AR response element, and the chromatin immunoprecipitation assay demonstrated that the complex composed of AR/LSD1 was bound to the ARE on E-cadherin and vimentin promoter and played demethylation activity and regulated gene transcription.Specifically, the ARR / LSD1 complex on the E-cadherin promoter removes the methylation of the epidermal modified H3K4 that activates gene expression, thereby inhibiting the gene expression, while AR-LSD1 on the E-cadherin promoter leads to a decrease in the methylation of the inhibitory epigenetic modified H3K9.In turn, it activates gene expression.Interference with AR or LSD 1, or the use of LSD1 inhibitors, will restore this demethylation, proving that both AR and LSD1 are essential in the process.In vivo, androgen treatment did not significantly affect the tumor size of breast cancer cells injected in situ in nude mice, but significantly enhanced the lung metastasis and vascular wall penetration of breast cancer cells, and interfered with the expression of AR or LSD1.Androgen AR and LSD1 do play an important role in this process.Clinical statistical analysis showed that the expression of AR and LSD1 had a certain effect on the survival time of breast cancer patients.If we further analyze the distribution of AR, we can find that the difference of the distribution of nucleus and cytoplasm is more obvious (we regard this phenomenon as a result of higher androgen level, and the clinical grade and prognosis of patients are worse.To sum up, we found a molecular pathway of "androgen-AR-rLSD1-breast cancer development and metastasis," which suggests the importance of hormone balance in women.The establishment of AR-D may be a new index for clinical diagnosis and analysis.
【学位授予单位】：东北师范大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：R737.9

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