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Background & Objective: In malignant transformation, mutant gene products and dysregulated proteins can become tumor antigens and activate immunoreactions. Therefore, auto-antibodies exist in sera of cancer patients. Serologic analysis of recombinant cDNA expression libraries (SEREX) using autologous and allogenic patient sera provides a powerful approach to identify tumor antigens. This study was to identify esophageal cancer antigens with SEREX for serologic diagnosis, gene therapy, and immune therapy., Methods: Expression library of cDNA from esophageal squamous cell carcinoma was constructed. SEREX screened out 21 positive clones from the 1.6x10(6) clones in the established library. The 21 positive clones were subcloned to monoclonality and submitted to in vivo excision of pBluescript phagemids. The nucleotide sequences of cDNA inserts were analyzed with DNASIS and BLAST software on EMBL and GenBank. According to the bioinformatics analyses, serologic immunoreactions of 4 colons in 10 samples of esophageal cancer serum and 10 samples of normal control serum were further detected by SADA., Results: Of the 21 positive clones, 4 had no homology to any known genes, 17 were known fragments which were defined as antigens of esophageal cancer for the first time. The serologic immunoreaction rates of 4 selected antigens, including Ribosomal protein S4, and so on, were 40%, 60%, 70%, and 30%, respectively, in cancer sera, and 0%, 10%, 20%, and 20%, respectively, in normal sera., Conclusions: Antigens, such as Ribosomal protein S4, are frequently involved in serologic immunoreactions of esophageal cancer. The 21 antigens identified by the present study can be used as potential targets for gene therapy and serologic biomarkers of esophageal cancer.

Background & Objective: NY-ESO-1 is a tumor antigen from cDNA library of esophageal carcinoma. However, there was no report about its expression in the tissue of esophageal carcinoma. In the current study, the authors examined the frequency of the NY-ESO-1 gene expression in esophageal carcinoma in order to determine whether NY-ESO-1 antigen-based vaccine therapy be available for the patients with esophageal carcinoma., Methods: Reverse transcriptase and polymerase chain reaction amplification techniques were utilized to assay 30 esophageal carcinoma tissues and the matched adjacent normal esophageal tissues for expression of NY-ESO-1 gene. And the cDNA sequence of NY-ESO-1 was cloned from esophageal carcinoma tissues by molecular cloning techniques., Results: Out of 30 esophageal carcinoma tissues, 50% expressed NY-ESO-1 gene while no expressed in the matched adjacent normal esophageal tissues. The sequence of NY-ESO-1 cloned was identical to the sequence of that from GenBank., Conclusions: NY-ESO-1 gene is expressed highly in esophageal carcinoma and NY-ESO-1 antigen can be recognized by cytolytic T lymphocytes when presented by HLA-class-I molecular.

One of the cardinal questions in tumor immunology is the identification of antigenic structures in human tumors that are recognized by host immune system. A powerful new methodology for identifying human tumor antigens eliciting humoral immune response is SEREX (serological identification of antigen by recombinant cDNA expression cloning). Here, by using this method, a recombinant cDNA expression library from lung cancer was analysed and several new tumor antigens were isolated. Using the lambda-ZAP vector, cDNA expression library was constructed from lung cancer tissues of three patients including a moderately differentiated lung adenocarcinoma, a highly differentiated lung squamous cell carcinoma and a moderately differentiated lung adeno-squamous carcinoma. The primary library consisted of 0.8 x 10(6) recombinants. 33 positive clones encoding antigen genes were obtained after immunoscreening, and the nucleotide sequences of cDNA inserts were determined and analysed with DNASIS and BLAST softwares in EMBL and GenBank. These antigen genes included known genes, such as MAGE (melanoma antigen gene), vitiligo-associated protein VIT-1, fibronectin, Na-K-ATPase et al and unknown genes or ESTs. To characterize expression profile of these genes, antibodies in sera from 48 lung cancer patients and 48 health donors were assayed with three antigens (L-8, L-19, L-51) to screen specific and relative serum markers for lung cancer. The results show that positive rates in lung cancer patients are higher than in health donors. Our research indicates that some of these antigens may be related to lung cancer and may be valuable tumor markers in diagnosis of lung cancer.