Background: Bronchoalveolar lavage (BAL) is a specific type of air-way fluid. It is a commonly used clinical specimen for the diagnosis of benign diseases and
cancers of the lung. Although previous studies have identified several disease-associated
proteins in the BAL, the potential utility of BAL in
lung cancer is still not well-studied. Based upon the fact that the majority of secreted
proteins are
glycoproteins, we have profiled N-
glycoproteins in BAL collected from
lung cancers, and investigated the expression of
glycoproteins such as the matrix N-
glycoprotein,
periostin, in
lung cancers. Methods: BAL specimens (n = 16) were collected from
lung cancer patients, and analyzed using mass spectrometry-based quantitative N-glycoproteomic technique. Additional BAL specimens (n = 39) were independently collected to further evaluate the expression of
periostin by using an
enzyme-linked
immunosorbent assay (ELISA). Results: A total of 462
glycoproteins were identified in BAL samples using N-glycoproteomic technique, including 290 in
lung adenocarcinoma (ADC, n = 5), 376 in
squamous cell carcinoma (SQCC, n = 4), 309 in
small cell lung carcinoma (SCLC, n = 4), and 316 in benign
lung disease (n = 3). The expressions of several
glycoproteins were elevated, including 8 in ADC, 12 in SQCC, and 17 in SCLC, compared to benign BALs. The expression of
periostin was detected in all subtypes of
lung cancers. To further investigate the expression of
periostin, an ELISA assay was performed using additional independently collected BALs (n = 39) The normalized levels of
periostin in benign disease, ADC, SQCC, and SCLC were 255 ± 104 (mean ± SE) and 4,002 ± 2,181, 3,496 ± 1,765, and 1,772 ± 1,119 ng/mg of total BAL
proteins. Conclusion: Our findings demonstrate that proteomic analysis of BAL can be used for the study of
cancer-associated extracellular
proteins in air-way fluid from
lung cancer patients.