肿瘤相关糖抗原Tn/sialyl-Tn抗原在人乳腺癌中的表达及机制研究

Breast cancer is a common malignancy in women, with high incidence and recurrence and metastasis. We detected the tumor-associated carbohydrate antigen Tn and sialyl-Tn antigens in human breast cancer by early immunohistochemical detection of small sample size. It was found that Tn and sialyl-Tn antigens were related to some clinical features of breast cancer, and the key regulatory genes (Cosmc, T-synthase) involved in the expression of Tn antigen have differences in Tn-positive and Tn-negative breast cancer. Tn/sialyl-Tn antigen is closely related to the development and progression of breast cancer, but its molecular mechanism is unclear. Based on our previous work, the subjects are to be studied as follows: (1) explore the expression of Tn/sialyl-Tn antigen in human breast cancer and its correlation with clinicopathological features and prognosis with large sample size; (2) The effect of O-glycan deficiency on the biological function of breast cancer cells was clarified by in vitro and in vivo experiments; (3) The molecular mechanism of the abnormal expression of Tn antigen was clarified by target-region capture sequence and methylation analysis. Our research will uncover the status and molecular mechanism of Tn/sialyl-Tn antigen in the development and progression of human breast cancer and provide some clues for their early diagnosis and targeted therapies in clinical practice.

乳腺癌是女性常见的恶性肿瘤，发病率高且易复发转移。我们前期通过小样本量的免疫组化检测，发现肿瘤相关糖抗原Tn和sialyl-Tn抗原在人乳腺癌中异常高表达，初步确立其与乳腺癌的一些临床特征有相关性，同时也发现了参与Tn抗原表达的关键调控基因（Cosmc、T-synthase）在Tn阳性和Tn阴性乳腺癌中存在表达差异。鉴于人乳腺癌中Tn/sialyl-Tn抗原异常表达的机制尚不清楚，本课题拟研究：（1）Tn/sialyl-Tn抗原在人乳腺癌病灶的表达及其与临床病理特征和预后的相关性；（2）通过体内外试验明确O-聚糖缺陷（即Tn抗原暴露）对乳腺癌细胞生物学功能的影响；（3）采用目标区域捕获测序、甲基化分析等方法明确乳腺癌中Tn抗原异常表达的机制。本课题将揭示Tn/sialyl-Tn抗原在人乳腺癌发生发展中的地位及机制，为寻找对乳腺癌有早期诊断、预后价值的生物标记物及治疗靶点提供重要理论基础。

乳腺癌是女性常见的恶性肿瘤，发病率高且易复发转移。近年来研究发现肿瘤相关糖抗原Tn和sialyl-Tn抗原在人乳腺癌中异常高表达，同时发现分子伴侣Cosmc参与Tn抗原的调控。然而，Cosmc和乳腺癌的关系尚未阐明。本研究围绕Cosmc参与乳腺癌侵袭转移的作用和机制开展深入研究。我们发现Cosmc的表达与Tn/sTn抗原表达呈负相关，且Cosmc mRNA水平表达与乳腺癌的分期相关。进一步我们在不同分子分型的乳腺癌细胞系中检测Cosmc的表达水平，采用慢病毒转染等方法，明确Cosmc介导Tn/T抗原相互转化的作用，Cosmc siRNA促进了乳腺癌细胞的增殖，侵袭和转移。体内实验同样验证了这一点。分析Cosmc及其下游通路结果显示，Cosmc可能通过影响PI3K-AKT-mToR信号通路活性从而影响乳腺癌的生物学行为。对Tn(+)乳腺癌组织进行Cosmc、T-synthase的目标区域测序，并未发现其存在基因突变。采用甲基化敏感PCR检测乳腺癌细胞， 在MDA-MB-231和MCF-7乳腺癌细胞中Cosmc基因启动子区域呈现高甲基化状态，Cosmc启动子甲基化可能是乳腺癌Tn/sTn抗原的表达机制之一。拓展sTn抗原在肿瘤免疫中的作用，我们发现乳腺癌中sTn抗原的高表达与PD-L1的表达，高CD8+T细胞浸润呈正相关，而且sTn和PD-L1共表达与乳腺癌患者的预后密切相关。另外，我们对导管内肿瘤患者病理性乳头溢液中检测了sTn抗原的表达，发现sTn抗原可以早期诊断和鉴别诊断导管内乳头状癌，说明sTn抗原可能参与了乳腺癌的发生。综上，本研究揭示了Cosmc在乳腺癌O-糖基化异常中的重要作用及其分子机制，为其应用于乳腺癌的防治奠定理论基础。