Scanlan Matthew J, Ritter Gerd, Yin Beatrice W T, Williams Clarence, Cohen Leonard S, Coplan Keren A, Fortunato Sheila R, Frosina Denise, Lee Sang-Yull, Murray Anne E, Chua Ramon, Filonenko Valeriy V, Sato Eiichi, Old Lloyd J, Jungbluth Achim A
Ludwig Institute for Cancer Research, New York Branch of Human Cancer Immunology at Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
Cancer Immun. 2006 Jan 12;6:2.
To identify novel, tissue-restricted cell surface proteins in cancer which can serve as targets for antibody-based diagnostics and therapeutics, a translated version of the expressed sequence tag database (tblastn) was mined for transcripts with similarity to the glycoprotein A33 (GPA33) colon cancer antigen. A novel human transcript, termed A34, was identified which encoded a putative cell surface protein, GPA34, which is approximately 30% identical to GPA33 and other members of the junctional adhesion molecule (JAM) family. Conventional end-point and quantitative real-time RT-PCR showed that A34 mRNA expression is highly tissue-restricted, as it is expressed predominantly in stomach and testis. A34 mRNA was also detected in 6/19 (31%) gastric cancers, 8/16 (50%) esophageal carcinomas, and 4/17 (23%) ovarian cancers, but not in lung, breast or colon carcinomas. A murine monoclonal antibody (mAb A34) was generated to the extracellular domain of the A34 protein and used to biochemically and immunohistochemically characterize the A34 antigenic system. The mAb A34 specifically recognized glycoproteins ranging in apparent size from 55-70 kDa, present in normal gastric mucosa and in COS-7 cells transfected with A34 cDNA. Of 31 different normal tissues examined by immunohistochemistry, GPA34 protein expression was detected primarily in normal stomach mucosa and testicular germ cells, and in the tumor cells of 5/17 (29%) gastric cancers, 7/11 (63%) esophageal cancers, and 2/21 (9%) ovarian cancers, in agreement with gene expression results. The A34 antigen and monoclonal antibody may be of considerable value for immunotherapy of different types of cancer.
为了鉴定癌症中可作为基于抗体的诊断和治疗靶点的新型组织限制性细胞表面蛋白，我们在表达序列标签数据库的翻译版本（tblastn）中搜索与糖蛋白A33（GPA33）结肠癌抗原相似的转录本。我们鉴定出一种新型人类转录本，命名为A34，它编码一种假定的细胞表面蛋白GPA34，该蛋白与GPA33及连接黏附分子（JAM）家族的其他成员约有30%的同一性。传统的终点法和定量实时逆转录聚合酶链反应（RT-PCR）表明，A34 mRNA表达具有高度的组织限制性，因为它主要在胃和睾丸中表达。在19例胃癌中有6例（31%）、16例食管癌中有8例（50%）、17例卵巢癌中有4例（23%）检测到A34 mRNA，但在肺癌、乳腺癌或结肠癌中未检测到。我们制备了针对A34蛋白细胞外结构域的鼠单克隆抗体（mAb A34），并用其对A34抗原系统进行生物化学和免疫组织化学特征分析。mAb A34特异性识别正常胃黏膜和转染了A34 cDNA的COS-7细胞中表观大小为55 - 70 kDa的糖蛋白。通过免疫组织化学检查的31种不同正常组织中，GPA34蛋白表达主要在正常胃黏膜和睾丸生殖细胞中检测到，在17例胃癌中的5例（29%）、11例食管癌中的7例（63%）和21例卵巢癌中的2例（9%）的肿瘤细胞中也检测到，这与基因表达结果一致。A34抗原和单克隆抗体可能对不同类型癌症的免疫治疗具有重要价值。
