PCDH17在乳腺癌中的甲基化状态及其调控乳腺癌细胞生长和转移的机理研究

Breast cancer has become the number one cause for cancer-related morbidity and mortality in women. Actively and effectively improving the early diagnosis of breast cancer is the key to the prevention and treatment of breast cancer. Epigenetics is very important for medical basic scientific research, and the investigation of epigenetic mechanism which is referring to DNA methylation, histone modification and mircoRNA will be better for us to understand the occurrence and development of breast cancer. Based on previous studies, the detection of DNA promoter methylation may provide a potentially possibility for early diagnosis of breast cancer. Recently, PCDH17 is regarded as a tumor suppressor gene. We preliminary experiments showed that PCDH17 is poorly expressed with its promoter hypermethylation in breast cancer, and exogenous expression of PCDH17 can inhibit breast cancer growth and metastasis through regulating Wnt/β-catenin and cell cycle-related signaling pathways. This project is designed to improve the early diagnosis of breast cancer through detecting PCDH17 promotor methylation in breast cancer tissues and related plasma, and analysing the correlation of PCDH17 methylation with clinicopathological features and outcome of breast cancer patients; Through our further investigation of the inhibitive function of PCDH17 on breast cancer cell, we can profoundly understand the molecular function of PCDH17 in the occurrence and development of breast cancer.

乳腺癌是目前女性最常见的恶性肿瘤，积极有效地提高乳腺癌的早期诊断是治疗乳腺癌的关键要素。表观遗传学是当今医学基础研究的热点，深入其机制的探讨有利于了解乳腺癌的发生和发展。其中，DNA甲基化的研究为乳腺癌的早期诊断提供了潜在的可能。PCDH17是新近发现的一个抑癌基因。我们的前期实验证PCDH17在乳腺癌中的表达缺失常常是由于其启动子高甲基化而引起,外源表达PCDH17可以通过调控Wnt/β-catenin及细胞周期相关的信号通路从而有效地抑制乳腺癌的生长和转移。本项目旨在通过检测乳PCDH17在乳腺癌临床样本组织和血浆中的甲基化状态,并分析PCDH17同乳腺癌临床分期分级、病理学特征及其预后的相关性,从而为提高乳腺癌的早期诊断及判断乳腺癌患者的预后提供参考;通过进一步深入探讨PCDH17调控乳腺癌生长和转移的机理研究,试图在分子学水平进一步了解其在乳腺癌发生和发展中的生物学作用。

背景：表观遗传学是当今医学基础研究的热点，深入其机制的探讨有利于了解乳腺癌的发生和发展。DNA甲基化的研究为乳腺癌的早期诊断提供了潜在的可能。PCDH17是新近发现的一个抑癌基因。我们的前期实验证PCDH17在乳腺癌中的表达缺失常常是由于其启动子高甲基化而引起,外源表达PCDH17可以通过调控Wnt/β-catenin及细胞周期相关的信号通路从而有效地抑制乳腺癌的生长和转移。.研究内容：检测PCDH17在乳腺癌临床样本组织和血浆中的甲基化状态,并分析PCDH17同乳腺癌临床分期分级、病理学特征及其预后的相关性；探讨PCDH17对乳腺癌细胞生长和转移的影响；探讨PCDH17与Wnt/β-catenin信号通路之间的相互关系；探讨PCDH17调控细胞周期与凋亡的分子学机制；探讨PCDH17调控乳腺癌细胞上皮间质转化（EMT）的机制。.研究结果：通过本课题证明了PCDH17在乳腺癌细胞株和临床乳腺癌样本组织中存在表达降低，利用MSP和BGS技术证实了其DNA启动子存在高频率的甲基化状态；通过本课题证明了PCDH17可以抑制乳腺癌的细胞周期和促进细胞凋亡从而调控乳腺癌细胞的生长和转移；通过本课题证明了PCDH17可以下调活性β-catenin从而调控Wnt/β-catenin信号通路及其下游基因表达；通过本课题证明了PCDH17可以上调E-cadherin的表达同时抑制Vimentin的表达从而影响乳腺癌细胞的上皮间质转化（EMT）。.结论：抑癌基因PCDH17在乳腺癌细胞株和临床乳腺癌样本中的表达水平明显降低，其DNA启动子存在高频率的甲基化，利用药物去甲基化可以重新恢复PCDH17表达，证明了DNA启动子甲基化是导致PCDH17表达水平降低的原因之一。体内和体外试验证明PCDH17可以通过调控Wnt/β-catenin信号通路及EMT相关因子从而影响乳腺癌细胞的周期与凋亡变化，从而抑制乳腺癌细胞的生长、侵袭和转移。