Takahashi M, Chen W, Byrd D R, Disis M L, Huseby E S, Qin H, McCahill L, Nelson H, Shimada H, Okuno K
Division of Oncology, Departments of Medicine and Surgery, University of Washington, Seattle, Washington 98195, USA.
Clin Cancer Res. 1995 Oct;1(10):1071-7.
The current study examined sera from 160 colon cancer patients and 60 normal individuals to determine whether antibody to mutated p21 ras protein was present. Studies focused on the aspartic acid substitution at amino acid position 12 (denoted D12), one of the most common mutations in colon adenocarcinoma. IgA antibodies directed against mutated p21 ras-D12 protein were detected in 51 (32%) of 160 colon cancer patients, but only in 1 (2.5%) of 40 normal individuals. The greater incidence of antibody in cancer patients provides presumptive evidence that immunization to the ras proteins occurred as a result of the malignancy. Examination of sera for antibody reactivity to wild-type p21 ras protein (denoted p21 ras-G12) as well as p21 ras proteins bearing the D12, V12, S12, or L61 mutations showed that antibody detected was largely to normal segments of the p21 ras protein. Epitope mapping, using peptide neutralization assays with mutated or normal ras peptides as competitors, demonstrated that in 10 (67%) of 15 sera examined the antibody reactivity to p21 ras-G12 protein was neutralized by peptides near the carboxyl terminus of p21 ras protein, but not by peptides spanning the specific point mutation region. Antibody reactivities correlated with peripheral blood lymphocyte count, but did not correlate with patient age, sex, histology, stage, tumor locus, lymph node metastasis, or serum carcinoembryonic antigen.
本研究检测了160例结肠癌患者和60例正常个体的血清，以确定是否存在针对突变型p21 ras蛋白的抗体。研究聚焦于第12位氨基酸的天冬氨酸替代（标记为D12），这是结肠腺癌中最常见的突变之一。在160例结肠癌患者中，有51例（32%）检测到针对突变型p21 ras-D12蛋白的IgA抗体，但在40例正常个体中仅1例（2.5%）检测到。癌症患者中抗体发生率更高，这提供了初步证据，表明对ras蛋白的免疫是由恶性肿瘤引起的。检测血清对野生型p21 ras蛋白（标记为p21 ras-G12）以及携带D12、V12、S12或L61突变的p21 ras蛋白的抗体反应性，结果显示检测到的抗体主要针对p21 ras蛋白的正常片段。使用突变或正常ras肽作为竞争者的肽中和试验进行表位作图，结果表明，在检测的15份血清中的10份（67%）中，对p21 ras-G12蛋白的抗体反应性被p21 ras蛋白羧基末端附近的肽中和，但未被跨越特定点突变区域的肽中和。抗体反应性与外周血淋巴细胞计数相关，但与患者年龄、性别、组织学、分期、肿瘤部位、淋巴结转移或血清癌胚抗原无关。
