FUT8介导糖基化修饰在乳腺癌侵袭转移中的作用及早期诊断价值研究

Glycosylation is one of the most common posttranslational modification reactions. Fucosylation is one of the most important glycosylation form in the course of tumorous development. However, we have not still understand what biological function of core fucosylation bring into play in the cells malignant transformation of human breast cancer. Our researchs early days have shown the overexpression of α-1,6 fucosyltransferase (FUT8) have not only promote the proliferation of breast cancer cells, but also could increase adhesion and migration ability abilities of breast cancer cells, suggesting that FUT8 plays an important role in the invasion, metastasis of tumor. Regard these as foundation, starting with cytology, histology, serology and other multi-level, this project will take advantage of gene transfection, siRNA and other means to adjust the level of core fucosylation, discussing effect and its adjustive mechanism of core fucosylation on invasion and metastasis abilities ability of breast cancer cells. Meanwhile, we will reveal the clinic meaning of FUT8 and core fucosylation from the level of histology. Finally, by analyzing serum core fucosylation level of atypical hyperplasia of mammary gland, carcinoma in situ and invasive breast cancer patients, we will appraise serum core fucosylation detection value to early clinical diagnosis of breast cancer, then tracing direct diagnostic marker and possible therapeutic targets of breast cancer, ultimately offering theoretical and experimental proof of early diagnosis and treat of breast cancer.

糖基化是最常见的翻译后修饰反应之一，岩藻糖基化修饰是肿瘤发生发展中最重要的糖基化形式。然而核心岩藻糖基化修饰在乳腺细胞恶性变过程中所发挥的具体生物学功能尚不清楚。我们前期工作证实，α-1,6岩藻糖基转移酶（FUT8）过表达不仅可以促进乳腺癌细胞的增殖，而且能增加乳腺癌细胞的黏附及迁移能力，提示其在促进肿瘤的侵袭转移上可能发挥着重要作用。本项目拟在此基础上，从细胞学、组织学、血清学等多层次入手，利用基因转染、siRNA等手段调控核心岩藻糖基化修饰水平，探讨核心岩藻糖基化修饰对乳腺癌细胞侵袭转移能力的影响及其调控机制；并从组织学水平揭示FUT8和核心岩藻糖基化修饰的临床意义；最后通过对乳腺不典型增生、原位癌、浸润性乳腺癌患者血清的核心岩藻糖化水平分析，评估血清核心岩藻糖检测对乳腺癌早期临床诊断的价值，为寻找乳腺癌直接的诊断标志物及潜在的治疗靶标，最终实现乳腺癌的早期诊治提供理论和实验依据。

异常核心岩藻糖基化与细胞恶性转化密切相关。本项目构建了α-1,6岩藻糖基转移酶（FUT8）重组体与siRNA干扰慢病毒载体转染乳腺癌细胞，发现沉默FUT8可显著抑制乳腺癌细胞恶性行为，包括细胞生长明显减慢、细胞克隆形成减少、细胞与基质胶粘附能力减弱、细胞迁移和侵袭能力下降；FUT8-siRNA能够下调MCF-7细胞表面分子Integrin-β1、Integrin-α3、E-cadherin、EGFR的岩藻糖基化水平，上调Integrin-α5蛋白表达和岩藻糖基化水平，从而通过调控Integrin、E-cadherin、EGFR的功能，影响乳腺癌细胞的增殖、粘附、迁移和侵袭；此外，FUT8表达的下调还伴随着p-FAK和NF-kB磷酸化程度的抑制，推测FUT8通过Integrin/FAK/NF-kB信号通路来调节乳腺癌细胞的生物学行为。本研究发现FUT8在乳腺癌组织中表达上调，并且与乳腺癌患者的肿瘤转移、疾病复发和不良预后相关。我们的研究不仅阐明了FUT8的病理学作用以及FUT8在乳腺癌中的调控机制，同时也发现FUT8可以作为乳腺癌一个非常有前途的预后指标和潜在治疗靶点。