title: Purification, identification and profiling of serum amyloid A proteins from sera of advanced-stage cancer patients.
abstract: Surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) is a powerful tool for screening potential biomarkers of various pathological conditions. However, low resolution and mass accuracy of SELDI-TOF-MS remain a major obstacle for determination of biological identities of potential protein biomarkers. We report here a refined workflow that combines ZipTip desalting, acetonitrile precipitation, high-performance liquid chromatography (HPLC) separation and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) analysis for the profiling, purification and identification of the targeted serum proteins found by SELDI-TOF-MS. By using this workflow, we purified ten targeted proteins from the sera of patients with various types of advanced stage (stage III-IV) cancers. These proteins were identified as isoforms of the human serum amyloid protein A (SAA) family with or without truncations at their N-terminals. This was confirmed by Western blot analysis. Different SAA expression patterns were observed by MALDI-TOF-MS profiling. SAA has long been reported as a biomarker for various cancer types such as lung cancer, ovarian cancer, and breast cancer. However, in this study we found increased SAA expression in the sera of advanced-stage cancer patients with different cancer types. Our results suggest that maybe SAA should not be used alone as a biomarker for any specific cancer type.
authors.affiliation: Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Zhensheng
authors.initials: Z
authors.lastname: Xie
authors.forename: Linan
authors.initials: L
authors.lastname: Shi
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhao
authors.forename: Junjie
authors.initials: J
authors.lastname: Hou
authors.forename: Xiulan
authors.initials: X
authors.lastname: Chen
authors.forename: Ziyou
authors.initials: Z
authors.lastname: Cui
authors.forename: Peng
authors.initials: P
authors.lastname: Xue
authors.forename: Tanxi
authors.initials: T
authors.lastname: Cai
authors.forename: Peng
authors.initials: P
authors.lastname: Wu
authors.forename: Sutang
authors.initials: S
authors.lastname: Guo
authors.forename: Fuquan
authors.initials: F
authors.lastname: Yang
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000595:Amino Acid Sequence; D014408:Biomarkers, Tumor / Q000097:blood* / Q000737:chemistry; D015153:Blotting, Western; D011232:Chemical Precipitation; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D008969:Molecular Sequence Data; D009367:Neoplasm Staging; D009369:Neoplasms / Q000097:blood* / Q000473:pathology; D020033:Protein Isoforms; D000685:Serum Amyloid A Protein / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000097:Acetonitriles; D014408:Biomarkers, Tumor; D020033:Protein Isoforms; D000685:Serum Amyloid A Protein; C032159:acetonitrile