Identification of candidate serum biomarkers for small cell lung cancer by proteomics analysis

Aim. Detection of novel tumor biomarker will aid in diagnosis of early-stage small cell lung cancer (SCLC). The purpose of this study was to identify novel tumor biomarker in serum from patients with SCLC using a proteomics-based approach. Methods. Sera were analyzed before the initiation of chemotherapy. Serum proteins of SCLC patients and healthy controls were collected and separated by 2-D fluorescence differential gel electrophoresis (2-D DIGE). Positive spots were analyzed by LC-MS/MS. Different expression of identified biomarker was verified by immunohistochemical method in wax specimen from 40 patients. Results. A total of 86 proteins were shown to be differentially abundant between the serum of SCLC patients and normal subjects by 2-D DIGE. Fifteen proteins were identified by LC-MS/MS. According to the bioinformatic analysis, these proteins are mainly involved in development and carcinogenesis. Some of them have been previously demonstrated to be important prognostic factors. Differential expression of 5 proteins between the normal tissue and cancerious tissue was confirmed by immunochemistry of SCLC patients. Conclusion. We have identified different serum proteins between SCLC patients and healthy controls. These proteins may be potential serum biomarkers for early detection of SCLC and play a role in the development and metastasis of SCLC.