Sensitive Multiplexed Quantitative Analysis of Autoantibodies to Cancer Antigens with Chemically S-Cationized Full-Length and Water-Soluble Denatured Proteins
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- 作者：Junichiro Futami ; Hidenori Nonomura ; Momoko Kido ; Naomi Niidoi ; Nao Fujieda ; Akihiro Hosoi ; Kana Fujita ; Komako Mandai ; Yuki Atago ; Rie Kinoshita ; Tomoko Honjo ; Hirokazu Matsushita ; Akiko Uenaka ; Eiichi Nakayama ; Kazuhiro Kakimi
- 刊名：Bioconjugate Chemistry
- 出版年：2015
- 出版时间：October 21, 2015
- 年：2015
- 卷：26
- 期：10
- 页码：2076-2084
- 全文大小：462K
- ISSN：1520-4812
文摘
Humoral immune responses against tumor-associated antigens (TAAs) or cancer/testis antigens (CTAs) aberrantly expressed in tumor cells are frequently observed in cancer patients. Recent clinical studies have elucidated that anticancer immune responses with increased levels of anti-TAA/CTA antibodies improve cancer survival rates. Thus, these antibody levels are promising biomarkers for diagnosing the efficiency of cancer immunotherapy. Full-length antigens are favored for detecting anti-TAA/CTA antibodies because candidate antigen proteins contain multiple epitopes throughout their structures. In this study, we developed a methodology to prepare purified water-soluble and full-length antigens by using cysteine sulfhydryl group cationization (S-cationization) chemistry. S-Cationized antigens can be prepared from bacterial inclusion bodies, and they exhibit improved protein solubility but preserved antigenicity. Anti-TAA/CTA antibodies detected in cancer patients appeared to recognize linear epitopes, as well as conformational epitopes, and because the frequency of cysteine side-residues on the epitope鈥損aratope interface was low, any adverse effects of S-cationization were virtually negligible for antibody binding. Furthermore, S-cationized antigen-immobilized Luminex beads could be successfully used in highly sensitive quantitative-multiplexed assays. Indeed, patients with a more broadly induced serum anti-TAA/CTA antibody level showed improved progression-free survival after immunotherapy. The comprehensive anti-TAA/CTA assay system, which uses S-cationized full-length and water-soluble recombinant antigens, may be a useful diagnostic tool for assessing the efficiency of cancer immunotherapy.