Coney L R, Tomassetti A, Carayannopoulos L, Frasca V, Kamen B A, Colnaghi M I, Zurawski V R
Cancer Research Division, Centocor, Malvern, Pennsylvania 19355.
Cancer Res. 1991 Nov 15;51(22):6125-32.
Monoclonal antibodies MOv18 and MOv19, raised against a membrane preparation of an ovarian carcinoma surgical specimen, react with a surface antigen present on the majority of nonmucinous ovarian malignant tumors tested but not with normal adult tissue (S. Miotti, S. Canevari, S. Ménard, D. Mezzanzanica, G. Porro, S. M. Pupa, M. Regazzoni, E. Tagliabue, and M. I. Colnaghi, Int. J. Cancer, 39: 297-303, 1987). This surface antigen was purified as a soluble glycoprotein (molecular mass, 36-38 kDa) released from the cell surface of an ovarian carcinoma cell line (IGROV1) by digestion with Bacillus thuringiensis phospholipase C. Immunoblotting demonstrated that the purified protein reacted with MOv18 and MOv19 and that treatment of the purified preparation with N-glycanase resulted in a protein with a molecular mass of 27 kDa. The NH3-terminal amino acid sequence of the purified antigen was determined. This sequence is highly homologous to an internal stretch of 27 amino acids located near the NH3 terminus of human folate-binding protein. An oligonucleotide probe was synthesized and used to screen an IGROV1 ovarian carcinoma, lambda gt11 complementary DNA library to obtain three complementary DNA clones. The complete nucleotide sequence of one of these complementary DNA clones was determined. This sequence is nearly identical to that of a folate-binding protein clone obtained from the Caco-2 human carcinoma cell line. In addition, the nucleotide sequence of the 5'-untranslated region of the other two clones was determined. This region of all three clones was different. The product of the Caco-2 folate-binding protein clone expressed in Chinese hamster ovary cells was recognized by the MOv18 and MOv19 antibodies, confirming that the antigen and folate-binding protein are one and the same. Furthermore, a cell line that binds the MOv18 and MOv19 antibodies expressed increased levels of folate-binding protein mRNA compared with a cell line that does not bind these antibodies. These results indicate that the MOv18 and MOv19 monoclonal antibodies bind to at least one form of folate-binding protein and that this protein, which is evidently overexpressed in certain malignant tumors, may provide a suitable target for immunotherapy with these antibodies.
针对卵巢癌手术标本膜制剂产生的单克隆抗体MOv18和MOv19，与大多数所检测的非黏液性卵巢恶性肿瘤表面存在的一种抗原发生反应，但不与正常成人组织发生反应（S. 米奥蒂、S. 卡内瓦里、S. 梅纳尔、D. 梅赞扎尼卡、G. 波罗、S. M. 普帕、M. 雷加佐尼、E. 塔利亚布埃和M. I. 科尔纳吉，《国际癌症杂志》，39: 297 - 303, 1987）。这种表面抗原被纯化成一种可溶性糖蛋白（分子量为36 - 38 kDa），它是通过用苏云金芽孢杆菌磷脂酶C消化从卵巢癌细胞系（IGROV1）的细胞表面释放出来的。免疫印迹表明，纯化后的蛋白与MOv18和MOv19发生反应，并且用N - 聚糖酶处理纯化制剂后产生一种分子量为27 kDa的蛋白。测定了纯化抗原的NH3 - 末端氨基酸序列。该序列与人叶酸结合蛋白NH3 - 末端附近的一段27个氨基酸的内部序列高度同源。合成了一个寡核苷酸探针，用于筛选IGROV1卵巢癌λgt11互补DNA文库，以获得三个互补DNA克隆。确定了其中一个互补DNA克隆的完整核苷酸序列。该序列与从Caco - 2人癌细胞系获得的叶酸结合蛋白克隆的序列几乎相同。此外，测定了另外两个克隆5' - 非翻译区的核苷酸序列。这三个克隆的该区域各不相同。在中华仓鼠卵巢细胞中表达的Caco - 2叶酸结合蛋白克隆的产物被MOv18和MOv19抗体识别，证实该抗原与叶酸结合蛋白是同一物质。此外，与不结合这些抗体的细胞系相比，结合MOv18和MOv19抗体的细胞系中叶酸结合蛋白mRNA的表达水平升高。这些结果表明，MOv18和MOv19单克隆抗体至少与一种形式的叶酸结合蛋白结合，并且这种蛋白在某些恶性肿瘤中明显过度表达，可能为用这些抗体进行免疫治疗提供合适的靶点。
