| Lung cancer is one of the most frequently diagnosed cancers, and it is aworld-wide leading cause of human cancer death. The incidence of lungcancer will keep increasing for a long time. In China, the incidence andmortality of lung cancer are also gradually increasing, which is the leadingcancer in urban area and the third cancer in rural area. Since there is noobvious symptom at early stage of lung cancer, 70-80% patients are inadvanced stage at the time of visit and have no chance for effective treatment,however, the 5-year survival rate of patients at stageâ… after operation could be80%. Early diagnosis of lung cancer has critical impact on effective treatmentand well prognosis. Theoretically, the most sensitive means for tumordiagnosis is molecular marker. Therefore, discovery of lung cancer molecularmarker is of great significance to prevention and cure of lung cancer. Tumorcells are nonself cells, which always express tumor antigens that are differentfrom the normal cells, and these tumor antigens can elicit immune system togenerate autoantibodies. Tumor associated antigens and autoantibodies areespecially promising serum biomarkers for tumor. An approach whichcombines conventional proteome analysis with serological screening,Serologic Proteome Analysis (SERPA), has some particular advantages inscreening serum markers (tumor associated antigens and autoantibodies).SERPA has been successfully applied to screening tumor markers withinspiring achievements. In this study, the most common type of lung cancer, lung squamouscarcinoma was studied. Proteins from twenty lung squamous carcinomatissues were separated by 2-DE, then Western blot imaging films reacted withthe patient autologous serum and with control serum were compared andtumor associated antigens were identified. There were 26 protein spots thatcould be recognized by sera of at least 15% patients with lung squamouscarcinoma. Analyzing by MALDI-TOF MS and ESI-Q-TOF MS, 19non-redundant proteins were identified successfully. These proteins consistedof members of proteins with diverse functions, including proteins related toglycometabolism, antioxidative stress, cell structure and chaperones.Furthermore, occurrence of autoantibodies against Tim and MnSOD wasevaluated by ELISA in additional 40 patients with lung squamous carcinoma,30 patients with other types of cancer and 50 non-cancer controls. Resultsshowed that frequency of autoantibodies against Tim and MnSOD in patientswith lung squamous carcinoma were 27.5% and 20% respectively, which weresignificantly higher than that in patients with other types of cancer (6.7% and6.7%) and in non-cancer controls (6% and 4%). These results were consistentwith that of the SERPA analysis. To investigate the mechanism forautoantibodies development, Western blot was performed to detect theexpression of Tim and MnSOD in 20 lung squamous carcinoma tissues andpaired normal bronchial epithelial tissues, the culture supernatant of humanlung squamous carcinoma cell line NCI-H520, 30 sera from patients with lungsquamous carcinoma and 30 normal sera. As a result, significantly increased expression of Tim and MnSOD were observed in lung squamous carcinomatissues, and both of them could be secreted by cultured lung squamouscarcinoma cell. Tim was detected in sera of patients with lung squamouscarcinoma, but no detectable Tim was found in the normal control.In this study, SERPA was applied to screen tumor associated antigens inhuman lung squamous carcinoma. The results indicated that Tim, MnSOD andtheir autoantibodies could be potential serum biomarkers for screening,diagnosis and immunotherapy of lung squamous carcinoma; We haveestablished a protein file for tumor antigens of lung squamous carcinoma,which provided powerful foundation for lung cancer biomarker discovery;Furthermore, we found that development of autoantibodies against Tim andMnSOD was possibly due to their overexpression and release into serum, andit provides important clues for the research in immunogenicity development oftumor antigens.
|
PDF Full Text Request