title: Immunogenic FEAT protein circulates in the bloodstream of cancer patients.
abstract: BACKGROUND
  FEAT is an intracellular protein that potently drives tumorigenesis in vivo. It is only weakly expressed in normal human tissues, including the testis. In contrast, FEAT is aberrantly upregulated in most human cancers. The present study was designed to investigate whether FEAT is applicable to tumor immunotherapy and whether FEAT is discernible in the bloodstream as a molecular biomarker of human cancers.
  
  
  METHODS
  Two mouse FEAT peptides with predicted affinities for major histocompatibility complex H-2Kb and H-2Db were injected subcutaneously into C57BL/6 mice before subcutaneous transplantation of isogenic B16-F10 melanoma cells. Intracellular localization of FEAT was determined by immunogold electron microscopy. Immunoprecipitation was performed to determine whether FEAT was present in blood from cancer patients. A sandwich enzyme-linked immunosorbent assay was used to measure FEAT concentrations in plasma from 30 cancer patients and eight healthy volunteers.
  
  
  RESULTS
  The vaccination experiments demonstrated that FEAT was immunogenic, and that immune responses against FEAT were induced without deleterious side effects in mice. Electron microscopy revealed localization of FEAT in the cytoplasm, mitochondria, and nucleus. Immunoprecipitation identified FEAT in the blood plasma from cancer patients, while FEAT was not detected in plasma exosomes. Plasma FEAT levels were significantly higher in the presence of cancers.
  
  
  CONCLUSIONS
  These findings suggest that FEAT is a candidate for applications in early diagnosis and prevention of some cancers.
authors.affiliation: Division of Molecular and Clinical Genetics, Kyushu University, Fukuoka, Japan.|Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Division of Molecular and Clinical Genetics, Kyushu University, Fukuoka, Japan.
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Division of Molecular and Clinical Genetics, Kyushu University, Fukuoka, Japan.|Department of Medical Biochemistry, Faculty of Medicine, Tanta University, Tanta, Egypt.
authors.forename: Marwa M
authors.initials: MM
authors.lastname: Mona
authors.affiliation: Division of Translational Cancer Research, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Satomi
authors.affiliation: Department of Innovative Applied Oncology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Okano
authors.affiliation: Division of Molecular and Clinical Genetics, Kyushu University, Fukuoka, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Inoue
authors.affiliation: Division of Molecular and Clinical Genetics, Kyushu University, Fukuoka, Japan.|Division of ALA Advanced Medical Research, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors.forename: Kenzaburo
authors.initials: K
authors.lastname: Tani
authors.affiliation: Division of Molecular and Clinical Genetics, Kyushu University, Fukuoka, Japan. atakah7@gmail.com.|Division of Translational Cancer Research, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan. atakah7@gmail.com.|Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan. atakah7@gmail.com.
authors.forename: Atsushi
authors.identifier: http://orcid.org/0000-0003-3340-432X
authors.initials: A
authors.lastname: Takahashi
keywords: Cancer prevention; Cancer screening; ELISA; FEAT; Immunotherapy; METTL13; Tumor marker