中文摘要：

人肠上皮细胞表面抗原A33是一种在人胃肠道上皮细胞特异性表达的跨膜糖蛋白，在95％以上的大肠癌、63％的胃癌和50％的胰腺癌中表达，而在其它组织或其它肿瘤细胞中鲜有表达。近年来就A33的组织特异性表达模式进行了深入的研究，揭示了与A33的特异性表达相关的特异性启动子和组织特异性转录因子（GKLF、CDX1）。A33抗体导向下的直肠癌放射免疫治疗已成为单克隆抗体（monoclonal antibody，MCAB）导向治疗研究领域的热点，且已经进入Ⅰ期放射免疫治疗临床实验。

英文摘要：

The human intestine tissue specific antigen A33 is a transmembrane glycoprotein and a novel member of the immunoglobulin superfamily. It is expressed in more than 95% of human co- lon cancers, 63% of gastric cancers and 50% of pancreatic cancers, and it has not been found to express in other tissues or cancers. Over the past years, a lot of work has been done on the tissuespecific expression profile, and scientists have identified the promotor and transcription factor （GKLF, CDX1 ） that are associated with specific expression of A33. Advances have been made in the research of monolclonal antibodies for radioimmunotherapy and now the study is in the phase Ⅰ trial in patients with advanced colorectal carcinoma.