OBJECTIVETo screen out effective lung cancer associated antigens for early diagnosis in order to improve the level of early diagnosis.

METHODSA T7 phage display cDNA library of human early lung cancer was developed. And then differential phage clones were picked out to be sequenced and bioinformatically analyzed. With the 8 screened differential phage clones a lung cancer associated antigen microarray was established to evaluate the single or combined roles of all the selected antigens in the diagnosis of lung cancer by the reaction of the antigens plus serum from normal subjects and patients with lung cancer, respectively.

RESULTSThe titer of the constructed cDNA library was 3.71×10 (6); pfu/ml and the number of phage was 1.11×10 (6); pfu, with a recombination rate of cDNA library over 90%. Nine differential phage clones were initially screened out, but the genes of two antigens (A42 and A83) were found the same. Bioinformatics analyses showed that the genes of the 8 antigens were known before and they were all proven to be related with tumor except A64. The positive reaction rates of the 8 antigens with serum from lung cancer patients were significantly higher than that with serum from normal subjects (Ps<0.05). When keeping specificity no less than 60%, the sensitivity of each antigen in predicting lung cancer alone was under 70% and the areas under curve (AUC) of the antigens were all under 0.8. However, when all the antigens were combined to detect lung cancer, the sensitivity and specificity was 90.8% and 94.1%, respectively, and AUC reached up to 0.969.

CONCLUSIONA T7 phage display cDNA library with a good quality of capacity, recombination rate and representativeness of human early lung cancer was successfully developed, and 8 lung cancer associated antigens were screened out. A combination of the 8 antigens can greatly improve their value to diagnose lung cancer with a higher sensitivity and specificity (both above 90%)．