Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
Breast Cancer Res. 2011 Mar 8;13(2):R25. doi: 10.1186/bcr2841.
Detection of serum biomarkers for early diagnosis of breast cancer remains an important goal. Changes in the structure of O-linked glycans occur in all breast cancers resulting in the expression of glycoproteins that are antigenically distinct. Indeed, the serum assay widely used for monitoring disease progression in breast cancer (CA15.3), detects a glycoprotein (MUC1), but elevated levels of the antigen cannot be detected in early stage patients. However, since the immune system acts to amplify the antigenic signal, antibodies can be detected in sera long before the antigen. We have exploited the change in O-glycosylation to measure autoantibody responses to cancer-associated glycoforms of MUC1 in sera from early stage breast cancer patients.
We used a microarray platform of 60mer MUC1 glycopeptides, to confirm the presence of autoantibodies to cancer associated glycoforms of MUC1 in a proportion of early breast cancer patients (54/198). Five positive sera were selected for detailed definition of the reactive epitopes using on chip glycosylation technology and a panel of glycopeptides based on a single MUC1 tandem repeat carrying specific glycans at specific sites. Based on these results, larger amounts of an extended repertoire of defined MUC1 glycopeptides were synthesised, printed on microarrays, and screened with sera from a large cohort of breast cancer patients (n = 395), patients with benign breast disease (n = 108) and healthy controls (n = 99). All sera were collected in the 1970s and 1980s and complete clinical follow-up of breast cancer patients is available.
The presence and level of autoantibodies was significantly higher in the sera from cancer patients compared with the controls, and a highly significant correlation with age was observed. High levels of a subset of autoantibodies to the core3MUC1 (GlcNAcβ1-3GalNAc-MUC1) and STnMUC1 (NeuAcα2,6GalNAc-MUC1) glycoforms were significantly associated with reduced incidence and increased time to metastasis.
Autoantibodies to specific cancer associated glycoforms of MUC1 are found more frequently and at higher levels in early stage breast cancer patients than in women with benign breast disease or healthy women. Association of strong antibody response with reduced rate and delay in metastases suggests that autoantibodies can affect disease progression.
检测血清生物标志物以实现乳腺癌的早期诊断仍然是一个重要目标。所有乳腺癌都会导致 O 连接糖链结构发生改变，从而导致糖蛋白表达发生改变，这些糖蛋白具有独特的抗原性。事实上，目前广泛用于监测乳腺癌疾病进展的血清检测法（CA15.3）检测的一种糖蛋白（MUC1），但在早期患者中无法检测到抗原的升高水平。然而，由于免疫系统可以放大抗原信号，因此在抗原之前很久就可以在血清中检测到抗体。我们利用 O-糖基化的变化来测量早期乳腺癌患者血清中针对 MUC1 癌症相关糖型的自身抗体反应。
我们使用了 60mer MUC1 糖肽微阵列平台，在一部分早期乳腺癌患者（54/198）中证实了针对 MUC1 癌症相关糖型的自身抗体的存在。选择了 5 份阳性血清，使用芯片糖基化技术和基于特定糖基在特定位置携带特定糖链的单个 MUC1 串联重复的糖肽进行详细定义反应表位。基于这些结果，我们合成了大量扩展的定义明确的 MUC1 糖肽，并将其打印在微阵列上，然后用来自大型乳腺癌患者队列（n=395）、良性乳腺疾病患者（n=108）和健康对照（n=99）的血清进行筛选。所有血清均于 20 世纪 70 年代和 80 年代采集，并且可以获得对乳腺癌患者的完整临床随访。
与对照组相比，癌症患者血清中自身抗体的存在和水平明显更高，并且与年龄呈高度显著相关。核心 3 MUC1（GlcNAcβ1-3GalNAc-MUC1）和 STnMUC1（NeuAcα2,6GalNAc-MUC1）糖型的一组自身抗体的高水平与较低的发病几率和转移时间延长显著相关。
与良性乳腺疾病或健康女性相比，早期乳腺癌患者的血清中更频繁且水平更高地发现针对特定癌症相关糖型的 MUC1 自身抗体。强烈的抗体反应与转移率降低和延迟相关表明，自身抗体可能会影响疾病进展。
