title: Identification and quantification of osteopontin splice variants in the plasma of lung cancer patients using immunoaffinity capture and targeted mass spectrometry.
abstract: The expression patterns and functional roles of three osteopontin splice variants (OPNa, b, and c) in cancer metastasis and progression are not well understood due to the lack of reliable assays to differentiate the isoforms. We have developed a mass spectrometric method to quantify OPN isoforms in human plasma. The method is based on the immunocapture of all OPN isoforms, followed by MRM-MS analysis of isoform-specific tryptic peptides. We were able to simultaneously identify and quantify all three isoforms in the plasma of 10 healthy individuals and 10 non-small cell lung cancer (NSCLC) patients. Our results show that none of the OPN splice variants is cancer specific. However, OPNa, the major isoform in healthy and NSCLC plasma, is substantially elevated in NSCLC patients, whereas OPNb and OPNc are at equivalent levels in two populations.
authors.affiliation: Global Biotherapeutic Technologies, Groton, CT, USA. jiang.wu@pfizer.com
authors.forename: Jiang
authors.initials: J
authors.lastname: Wu
authors.forename: Pooja
authors.initials: P
authors.lastname: Pungaliya
authors.forename: Eugenia
authors.initials: E
authors.lastname: Kraynov
authors.forename: Brian
authors.initials: B
authors.lastname: Bates
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D000595:Amino Acid Sequence; D002289:Carcinoma, Non-Small-Cell Lung / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D005091:Exons; D006801:Humans; D047468:Immunoprecipitation; D008175:Lung Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D053495:Osteopontin / Q000097:blood* / Q000235:genetics; D010446:Peptide Fragments / Q000032:analysis; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D012334:RNA, Neoplasm / Q000235:genetics*; D014481:United States
chemical_list: D010446:Peptide Fragments; D020033:Protein Isoforms; D012334:RNA, Neoplasm; D053495:Osteopontin