Comparative study of protein markers in serum and bronchoalveolar lavage fluid from patients with lung cancer by surface-enhanced laser desorption ionization time of flight mass spectrometry

Abstract

To detect the protein markers in serum and bronchoalveolar lavage fluid (BALF) of the patients with lung cancer by surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS) technology, and to explore if they can be used as markers for the diagnosis of lung cancer. SELDI-TOF-MS technology and protein chips weak cation exchange (WCX-2 chip) were used to detect the protein mass spectrum in serum and BALF of 35 patients with lung cancer and 18 cases of benign pulmonary diseases. The different protein markers were analyzed by Biomarker Pattern Software and the initial diagnosis models were set up. The diagnosis models were verified further by blind screen to confirm the efficacy of diagnosis. Five protein peaks in the sera of the patients with lung cancer were significantly higher (P < 0.05). The protein peak with a mass/charge ratio (M/Z) of 5639 was selected to establish the classification tree model. The sensitivity of diagnosis was 80% (28/35) and the specificity was 78% (14/18). The results verified by blind screen showed a sensitivity of 85% (17/20), a specificity of 90% (9/10), a crude accuracy (CA) of 87% (26/30) and Youden's index (γ) of 0.7. Eight protein peaks in the BALF of the patients with lung cancer were significantly higher (P < 0.05). The different protein peaks with M/Z of 7976 and 11 809 respectively were selected to establish the classification tree model. The sensitivity of diagnosis was 86% (30/35) and the specificity was 72% (13/18). The results verified by blind screen showed a sensitivity of 90% (18/20), a specificity of 90% (9/10), a CA of 90% (27/30) and γ of 0.8. There was a complementary role in combination of differential proteins in serum and BALF and the sensitivity, specificity and accuracy of diagnosis for lung cancer were 100% by parallel test. The SELDI-TOF-MS technology can screen out the differential protein markers in serum and BALF of the patients with lung cancer, which show high sensitivity and specificity as tumor markers. The differential proteins in the BALF may be more promising for clinical application.