Imam S A, Mills L A, Taylor C R
Department of Pathology, University of Southern California, School of Medicine, Los Angeles 90033.
Br J Cancer. 1991 Dec;64(6):1001-10. doi: 10.1038/bjc.1991.455.
A tumour-associated antigen (TAA.62) with an apparent mol. wt. of 62 kd, identified by a human monoclonal antibody (IgG2, kappa-light chain), was found to be expressed at elevated levels in the cytoplasmic compartment of malignant as compared with normal mammary epithelial cells in both tissues and cultured cells. Increased levels of cytoplasmic expression of the antigen were also observed in malignant cells of cervix, colon, kidney, lung, and stomach. The patterns of expression of TAA.62 in cultured cells mirrored those of tissues and the antigen was expressed at elevated levels in the established breast cancer lines or oncogenically transformed mammary carcinoma cell line (tumourigenic) compared with the immortalised mammary epithelial cell line (non-tumourigenic). Aliquots of TAA.62 were purified to homogeneity from the conditioned-medium of malignant and immortalised breast cells by immunoaffinity chromatography using immobilised anti-TAA.62 antibody, and gel filtration. Both preparations of TAA.62 yielded a single band with an apparent molecular weight of 62 kd under reducing condition on sodium dodecyl sulphate-polyacrylamide gel electrophoresis, and both were identical in terms of size and immunoreactivity to anti-TAA.62 antibody. However, TAA.62(T) isolated from tumourigenic cell lines itself interacted with a cell surface molecule having an apparent molecular weight of 160 kd on both the malignant and immortalised cells: TAA.62(I) isolated from immortalized cell lines, showed no comparable interaction. Scatchard analysis of the concentration-dependent binding of TAA.62(T) to 160 kd-receptor molecule revealed a 2.6 x 10(4) binding sites per cell. The association constant of such binding was determined to be approximately 16.6 nM. Finally, addition of anti-TAA.62 antibody to culture medium resulted in the inhibition of proliferation of the malignant cells, but showed no effect on the normal cells. The results suggest that TAA.62 may interact as a ligand with its 160 kd cell surface receptor with a possible growth related function.
一种由人单克隆抗体（IgG2，κ轻链）识别的、表观分子量为62kd的肿瘤相关抗原（TAA.62），发现在组织和培养细胞中，与正常乳腺上皮细胞相比，其在恶性细胞的细胞质区室中表达水平升高。在子宫颈、结肠、肾脏、肺和胃的恶性细胞中也观察到该抗原细胞质表达水平的增加。TAA.62在培养细胞中的表达模式与组织中的相似，并且与永生化乳腺上皮细胞系（非致瘤性）相比，该抗原在已建立的乳腺癌细胞系或致癌转化的乳腺癌细胞系（致瘤性）中表达水平升高。通过使用固定化抗TAA.62抗体的免疫亲和层析和凝胶过滤，从恶性和永生化乳腺细胞的条件培养基中纯化得到均一的TAA.62等分试样。在还原条件下，两种TAA.62制剂在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳上均产生一条表观分子量为62kd的条带，并且在大小和与抗TAA.62抗体的免疫反应性方面均相同。然而，从致瘤性细胞系中分离的TAA.62（T）自身与恶性细胞和永生化细胞上一种表观分子量为160kd的细胞表面分子相互作用：从永生化细胞系中分离的TAA.62（I）未显示出类似的相互作用。对TAA.62（T）与160kd受体分子的浓度依赖性结合进行Scatchard分析，结果显示每个细胞有2.6×10⁴个结合位点。这种结合的缔合常数测定为约16.6nM。最后，向培养基中添加抗TAA.62抗体导致恶性细胞增殖受到抑制，但对正常细胞无影响。结果表明，TAA.62可能作为配体与其具有可能生长相关功能的160kd细胞表面受体相互作用。
