Purpose: Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, mainly due to late diagnosis and poor prognosis. Saliva is an important source for discovering biomarkers and contains an abundance of biological information. The purpose of this study was to determine whether galactosylation levels of salivary proteins are associated with LC.
Experimental design: First, we analyzed the alterations of the glycopatterns recognized by Bandeiraea Simplicifolia Lectin I (BS-I) in five groups (healthy volunteers [HV]: 28, benign pulmonary disease [BPD]: 27, lung adenocarcinoma [ADC]: 39, squamous cell carcinoma [SCC]: 28, small-cell lung cancer [SCLC]: 22) of 144 saliva samples using lectin microarrays. Pooled samples from each group were subsequently validated by the lectin blotting technique. Finally, the N-glycan profiles of their salivary glycoproteins isolated by the BS-I-magnetic particle conjugates from pooled samples for each group were analyzed by MALDI-TOF/TOF-MS.
Results: The results showed that the expression level of galactosylated glycans recognized by BS-I was significantly increased in patients with LC compared with BPD and HV. Receiver operating characteristic (ROC) analysis indicated that the levels of salivary glycopattern recognized by BS-I could discriminate lung disease (BPD, ADC, SCC, and SCLC) and HV with an AUC of 0.700 (95% CI: 0.589-0.812), and discriminate LC and BPD with an AUC of 0.860 (95% CI: 0.763-0.956). Also, the proportion of galactosylated N-glycans in ADC (38.4%), SCC (43.1%), and SCLC (39.5%) increased compared to HV (30.1%) and BPD (33.7%), and two galactosylated N-glycan peaks (m/z 1828.683, 2418.853) could be identified only in the LC groups (ADC, SCC, and SCLC).
Conclusions and clinical relevance: These findings could provide crucial information on galactosylated N-linked glycans associated with LC and facilitate the study of LC biomarkers based on precise alterations of galactosylated N-glycans in saliva.
Keywords: MALDI-TOF/TOF-MS; galactosylation; lectin microarray; lung cancer; saliva.
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