title: Identification of a novel SEREX antigen family, ECSA, in esophageal squamous cell carcinoma.
abstract: BACKGROUND
  Diagnosis of esophageal squamous cell carcinoma (SCC) may improve with early diagnosis. Currently it is difficult to diagnose SCC in the early stage because there is a limited number of tumor markers available.
  
  
  RESULTS
  Fifty-two esophageal SCC SEREX antigens were identified by SEREX (serological identification of antigens by recombinant cDNA expression cloning) using a cDNA phage library and sera of patients with esophageal SCC. Sequence analysis revealed that three of these antigens were similar in amino acid sequences, and they were designated as ECSA (esophageal carcinoma SEREX antigen)-1, -2 and -3. The ECSA family was also similar to an EST clone, hepatocellular carcinoma-associated antigen 25a (HCA25a). Serum antibody levels to ECSA-1, -2 and -3 were significantly higher in patients with esophageal SCC than in healthy donors. Based on the conserved amino acid sequences, three peptides were synthesized and used for enzyme-linked immunosorbent assays (ELISA). The serum antibody levels against one of these peptides were significantly higher in patients with esophageal SCC. This peptide sequence was also conserved in FAM119A, GOSR1 and BBS5, suggesting that these are also ECSA family members. Reverse transcription followed by quantitative PCR analysis showed that the mRNA expression levels of ECSA-1, -2 and -3 and FAM119A but not of HCA25a, GOSR1 and BBS5 were frequently elevated in esophageal SCC tissues.
  
  
  CONCLUSIONS
  We have identified a new gene family designated ECSA. Serum antibodies against the conserved domain of the ECSA family may be a promising tumor marker for esophageal SCC.
authors.affiliation: Department of Biochemistry and Genetics, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.|Department of Frontier Surgery, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Kagaya
authors.affiliation: Department of Surgery, School of Medicine, Toho University, Ota-ku, Tokyo 143-8541, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Shimada
authors.affiliation: Department of Frontier Surgery, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Tooru
authors.initials: T
authors.lastname: Shiratori
authors.affiliation: Department of Biochemistry and Genetics, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.|Department of Frontier Surgery, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Kuboshima
authors.affiliation: Department of Biochemistry and Genetics, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.|Department of Frontier Surgery, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Kazue
authors.initials: K
authors.lastname: Nakashima-Fujita
authors.affiliation: Department of Biochemistry and Genetics, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Yasuraoka
authors.affiliation: Department of Frontier Surgery, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Nishimori
authors.affiliation: Department of Surgery, School of Medicine, Toho University, Ota-ku, Tokyo 143-8541, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Kurei
authors.affiliation: Product Development Department, Medical & Biological Laboratories Co., Ltd., Ina, Nagano 396-0002, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Hachiya
authors.affiliation: Product Development Department, Medical & Biological Laboratories Co., Ltd., Ina, Nagano 396-0002, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Murakami
authors.affiliation: Department of Bioinfomatics, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tamura
authors.affiliation: Department of Molecular Diagnosis, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Nomura
authors.affiliation: Gastroenterological Center, San-Ai Memorial Hospital, Chuo-ku, Chiba 260-0806, Japan.
authors.forename: Takenori
authors.initials: T
authors.lastname: Ochiai
authors.affiliation: Department of Frontier Surgery, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Hisahiro
authors.initials: H
authors.lastname: Matsubara
authors.affiliation: Department of Biochemistry and Genetics, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Takiguchi
authors.affiliation: Department of Biochemistry and Genetics, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Takaki
authors.initials: T
authors.lastname: Hiwasa