Abstract. The aim of this study was to identify serum protein fingerprints of small cell lung cancer (SCLC) and potential biomarkers related to chemotherapy resistance of SCLC with surface enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF MS). A total of 60 SCLC patients and 48 age-and sex-matched healthy individuals were enrolled. The chemotherapy regimen was cisplatin plus etoposide. All patients received two cycles of chemotherapy. Serum protein profiles were detected using SELDI-TOF MS and the spectra were analyzed with support vector machines (SVMs). Western blotting was performed to verify the results of SELDI-TOF MS. Three top scored peaks, at m/z of 6269, 9043 and 13124 Da, were finally selected as potential biomarkers for detection of SCLC. The SVM classifier separated the SCLC from the healthy samples in the blind test, with a sensitivity of 92.4% and a specificity of 92.5%. For the 56 eligible chemotherapy patients, 4 had a complete response (7.14%), 39 patients had a partial response (69.6%), 9 patients had a stable disease (16.1%) and 4 patients had a progressive disease (7.14%). The model constructed using two protein peaks with m/z of 8830 and 10468 Da separated the chemotherapy-resistant group from the chemotherapy-sensitive group with a sensitivity of 80.0% and a specificity of 80.0%. Initial protein database searching identified 10468 Da as S100-A9 which was confirmed by western blotting. The present results suggest that the combination of SELDI-TOF MS with SVM may provide a useful means in the search for serum biomarkers for predicting chemotherapy resistance in patients with SCLC.
IntroductionLung cancer is the leading cause of cancer death in the world. In 2011, an estimated 221,000 new cases of lung and bronchial cancer will be diagnosed, and 156,900 deaths are estimated to occur due to the disease. Only approximaely 15.6% of all lung cancer patients are alive 5 years or more after diagnosis (1). Human lung cancers comprise two major groups, small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). SCLC accounts for appoximately 15% of all lung cancers. When compared with NSCLC, SCLC generally has a more rapid doubling time, a higher growth fraction, and earlier development of widespread metastases (2). Most patients with SCLC present with hematogenous metastases, while only about one third of patients with limited disease confined to the chest (3).For all patients with SCLC, chemotherapy is an essential component of appropriate treatment. Adjuvant chemotherapy is recommended for those who have undergone surgical resection. For patients with limited stage SCLC and good performance status (PS) (0-2), recommended treatment consists of chemotherapy with concurrent thoracic radiotherapy. For patients with extensive stage disease, chemotherapy alone is the recommended treatment and combination chemotherapy has been shown to be active in SCLC (4). Etoposide and cisplatin (EP) combination is the most commonly used initial chemotherapy regimen. Although pr...