Tissue specificity of Carcinoembryonic antigen

癌胚抗原（CEA）是一种癌胚细胞表面糖蛋白。由于其在肿瘤中的高表达和分泌到血清中，CEA已被广泛用作血清肿瘤标志物。为了研究CEA的组织特异性，我们使用蛋白质组学策略检测了CEACAM家族成员的表达模式和来自几种癌细胞系的CEA分子的n -糖基化模式。我们在CEA上发现了新的n -糖基化位点，进一步的精确研究揭示了不同癌细胞系的n -糖基化模式是不同的。此外，在胃肠道癌细胞系中发现了两个新的CEA剪接变体。这些转录本在正常组织中不表达。该剪接变体衍生的CEA蛋白异构体也在癌细胞中表达，并分泌到培养基中。我们还发现CEACAM4的表达是甲状腺髓样癌细胞系所特有的。

Carcinoembryonic antigen (CEA) is an oncofetal cell surface glycoprotein. Because of its high expression in tumors and secretion to serum, CEA has been widely used as a serum tumor marker. To investigate the tissue specificity of CEA, we examined the expression patterns of CEACAM family members and the N-glycosylation patterns on CEA molecules derived from several cancer cell lines using a proteomic strategy. We identified novel N-glycosylation sites on CEA and further precise investigation revealed that the N-glycosylation patterns were varying among various cancer cell lines. Furthermore, two novel CEA splice variants were identified in gastrointestinal cancer cell lines. Those transcripts were not expressed in normal tissues. CEA protein isoforms derived from the novel splice variants were also expressed in cancer cell lines, and those protein isoforms were secreted to culture medium. We also found that CEACAM4 expression was unique to a medullary thyroid carcinoma cell line.