Differential Proteomic Analysis Of Lung Squamous Carcinoma Patient And Healthy Sera

Lung cancer is one of the common malignant tumors and it is a world-wide leading cause of human cancer death. In China, the incidence and mortality of lung cancer rank the first place in the city and the third in the countryside. Lack of the effective early diagnosis method is the main reason of the high mortality and poor prognosis. Theoretically, a molecular marker is the most sensitive indicator for early diagnosis of cancer. Therefore, screening for biomarkers with high sensitivity and fine specificity have become the key to early diagnosis for lung cancer.In this study, 2-DE(two-dimensional gel electrophoresis) combined with MS (mass Spectrometry) and SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) combined with MS, were performed to screen the differential proteins from healthy subjects and stage 1 lung squamous carcinoma patient sera.First,2-DE and SDS-PAGE were used to separate proteins from healthy subjects and patient sera, respectively. The protein spots and bands were analyzed by the image analysis software and the differential protein spots and bands were identified by ESI-Q-TOF MS/MS (Electrospray ionization- quadrupole time of flight mass Spectrometry). And then,western blot and immunohistochemistry were used to determine the expression level of haptoglobin-2(HP-2) , one of the differential proteins identified by two technical routs, in the serum and tissue,respectively. The clinical significance as well as the cause of HP-2 regulation in serum were investigated.Through 2-DE in combination with MS,ten differential protein spots were detected and four proteins, including AIM,Transthyretin-related, Retinol Binding Protein and Hp-2, were identified.Through SDS-PAGE in combination with MS ,five differential protein bands were detected, and fifty proteins were identified. Western blot analysis showed that the serum expression level of HP-2 in patient was significantly higher than that in healthy subject, but was not associated with the stage of the Lung squamous carcinoma. Immunohistochemistry showed that the expression level of HP-2 in the lung squamous carcinoma tissues was higher than that in the adjacent normal bronchial epithelial tissues.The results indicated that HP-2 is the candidate biomarker for lung squamous carcinoma, and the serum level of HP-2 might be useful for diagnosis of lung squamous carcinoma. Up-regulated expression of HP-2 in the lung squamous carcinoma tissues may contribute to the high serum level of HP-2 in the patients.