Proteomic identificafion of secreted protein DDH in non-small cell lung cancer / 肿瘤

ABSTRACT

Objective: To identify secreted proteins of non-small cell lung cancer (NSCLC) and provide candidate molecule for screening serological biomarkers of lung cancer. Methods: NSCLC cell line A 549 cells were cultured. The proteins in the conditioned medium were collected and identified by proteomic analysis and spectrometry. Identified protein was confirmed by Western blotting in the conditioned medium. Fifteen NSCLC tissues and paired distant lung tissues were obtained simultaneously during surgery. The expression difference between cancer tissues and non-malignant lung tissues were analyzed by RT-PCR, Western blotting, and immunochemistry. One hundred and four cases of serum specimens were collected from NSCLC patients (n = 64), non-malignant lung tumor patients (n = 20) and healthy controls (n = 20). Serum level of dehydrodiol dehydrogenase (DDH) was analyzed by ELISA. Results: DDH was identified by proteomic approach and confirmed by Western blotting in the conditioned medium of A 549 cells. RT-PCR, Western blot, and immunochemistry analysis showed that over-expression of DDH mRNA and protein were detected in NSCLC cancer tissues compared with distant non-malignant lung tissues (P < 0.05). Abundant DDH was observed in cytoplasm and membrane of lung cancer cells. The serum level of DDH was significantly higher in NSCLC patients than that in non-malignant lung tumor patients and healthy controls (P < 0. 05). Conclusion: DDH is over-expressed in lung cancer tissues and the serum level of DDH is elevated in NSCLC patients. The secreted DDH protein is a serological biomarker of NSCLC.