LATE-BREAKING ABSTRACT: A proteomic study of benign and malignant pleural effusions

Objective: Our study utilised proteomics to acquire and analyse the protein profiles of both benign and malignant pleural effusions,to seek useful protein biomarkers with diagnostic value and to establish the diagnostic model for different types of pleural effusions. Method: We utilised the weak cationic-exchanger magnetic bead (WCX-MB) to purify the peptides found invarious pleural effusions, and used matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS) to generate peptide expression profiles from both the benign and malignant pleural effusion samples; we also established and validated the diagnostic modelusing a genetic algorithm (GA), and identified a promising protein biomarker. Results: The GA diagnostic model was established using spectra of 3930.9 m/z and 2942.8 m/z, including 25 malignant pleural effusion samples and 26 benign pleural effusion samples, yielding both a 100% sensitivity and a 100% specificity. The accuracy of this method was validated independently using 58 malignant pleural effusion samples and 34 benign pleural effusion samples. The results of a blinded evaluation were as follows: the sensitivity was 89.6%; the specificity was 88.2%; the PPV was 92.8%, and the NPV was 83.3%; the accuracy was 89.1%. Conclusion: Therefore, this model is suitable for distinguishing betweenbenign and malignant pleural effusions. The following was the most promising peptide biomarker: Isoform 1 of Caspase recruitment domain-containing protein 9 (CARD9), noted at 3930.9 m/z, the levels of which weredecreased in the malignant pleural effusion samples.