Molecular identity of a pan cancer marker, CA215
Molecular identity of a pan cancer marker, CA215
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DOI：
10.4161/cbt.7.12.6984
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发表时间：
2008-12-01
影响因子：
3.6
通讯作者：
Ting, Hong Hoi
中科院分区：
文献类型：
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作者：
Lee, Gregory;Laflamme, Emily;Ting, Hong Hoi
对肿瘤相关抗原CA215与RP215单抗及其唯一表位S反应的分子性质进行了研究。RP215最初是从3000个杂交瘤细胞中挑选出来的，这些杂交瘤是用OC-3-VGH卵巢癌细胞的细胞提取物免疫的小鼠产生的。用基质吸附激光解吸电离飞行时间质谱仪(MALDI-TOF MS)、Western印迹、糖谱分析和酶免疫分析等方法对来自癌细胞提取液、脱落培养液和亲和纯化形式的肿瘤相关抗原进行了分析。这项研究的结果表明，CA215与人免疫球蛋白重链同源，分子大小在50-70 KDa之间，当用RP215或抗人免疫球蛋白G、A或M探针时，用NaIO4处理癌细胞可显著减少RP215与位于人免疫球蛋白重链可变结构域的CA215的糖相关表位(S)的结合。进一步的研究表明，CA215主要由癌细胞以分泌型和膜结合型单体形式表达。具有pH敏感免疫活性的糖类相关表位(S)似乎只存在于癌细胞来源的免疫球蛋白中，而不存在于正常人类免疫球蛋白中。与正常免疫球蛋白G相比，CA215在O-连接的糖链中含有更多的N-乙酰和N-糖基神经氨酸(28%比8%)，而在N-连接的糖链中N-乙酰氨基葡萄糖的含量更低(28%比41%)。这项研究表明，RP215与多种人类癌细胞表达的免疫球蛋白重链的糖类相关表位(S)发生特异性反应。
The molecular nature of cancer-associated antigen, CA215 which reacts with RP215 monoclonal antibody and its unique epitope(s) was characterized. RP215 was initially selected and produced from one of 3,000 hybridomas which were generated from mice immunized with the cell extract of OC-3-VGH ovarian cancer cells. This cancer-associated antigen from various sources including cancer cell extract, shed culture medium and affinity-purified forms was analyzed by MALDI-TOF MS (Matrix Adsorption Laser Desorption Ionization-Time of Flight Mass Spectrometry), Western blot, carbohydrate profiling as well as enzyme immunoassays. The results of this study showed that CA215 is homologous to the heavy chains of human immunoglobulins with molecular sizes ranging from 50 to 70 KDa, when probed with RP215 or anti-human immunoglobulin G, A or M. Treatments of cancer cells with NaIO4 drastically reduce RP215 binding to the carbohydrate-associated epitope(s) of CA215 located on the variable domain of the human immunoglobulin heavy chains. Further studies indicated that CA215 is predominantly expressed by cancer cells in both secreted and membrane-bound monomeric forms. The carbohydrate-associated epitope(s) with pH-sensitive immunoactivity appear to be present only in cancer cell-derived immunoglobulins, but not in normal human immunoglobulins. Compared to normal immunoglobulin G, CA215 contains a significantly higher percentage of N-acetyl and N-glycoyl neuraminic acid (28% vs. 8%) in the O-linked glycans, but a lower content of N-acetylglucosamine (28% vs. 41%) in the N-linked ones. It was concluded from this study that RP215 reacts specifically with carbohydrate-associated epitope(s) of immunoglobulin heavy chains expressed by various human cancer cells.