International Journal of Molecular Sciences Article Cyclic Peptide Mimotopes for the Detection of Serum Anti–ATIC Autoantibody Biomarker in Hepato-Cellular Carcinoma Chang-Kyu Heo 1, Hai-Min Hwang 1, Won-Hee Lim 1,2, Hye-Jung Lee 3, Jong-Shin Yoo 4, Kook-Jin Lim 3 and Eun-Wie Cho 1,2,* 1 Rare Disease Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Korea;
[email protected] (C.-K.H.);
[email protected] (H.-M.H.);
[email protected] (W.-H.L.) 2 Department of Functional Genomics, University of Science and Technology, 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Korea 3 ProteomeTech Inc. 401, Yangcheon-ro, Gangseo-gu, Seoul 07528, Korea;
[email protected] (H.-J.L.);
[email protected] (K.-J.L.) 4 Biomedical Omics Group, Korea Basic Science Institute, 162 YeonGuDanji-Ro, Ochang-eup, Cheongju, Chungbuk 28119, Korea;
[email protected] * Correspondence:
[email protected]; Tel.: +82-42-860-4155 Received: 12 November 2020; Accepted: 16 December 2020; Published: 19 December 2020 Abstract: Tumor-associated (TA) autoantibodies have been identified at the early tumor stage before developing clinical symptoms, which holds hope for early cancer diagnosis. We identified a TA autoantibody from HBx-transgenic (HBx-tg) hepatocellular carcinoma (HCC) model mouse, characterized its target antigen, and examined its relationship to human HCC. The mimotopes corresponding to the antigenic epitope of TA autoantibody were screened from a random cyclic peptide library and used for the detection of serum TA autoantibody. The target antigen of the TA autoantibody was identified as an oncogenic bi-functional purine biosynthesis protein, ATIC.