Phosphoglycerate kinase 1 as a candidate of tumor-associated antigen identified from esophageal squamous cell carcinoma.
Shijie Huaren Xiaohua Zazhi 2008;
16:1866-1872. [DOI:
10.11569/wcjd.v16.i17.1866]
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Abstract
AIM: To investigate and identify novel tumor-associated antigens in esophageal squamous cell carcinoma (ESCC).
METHODS: Modified serological proteome analysis (mSERPA) strategy was used to separate and identify the candidate proteins. The subcellular protein fractions (cytosolic, membrane and nuclear fractions) of ESCC cell lines and EC0156 cells were extracted first and then cytosolic proteins were separated using SDS-PAGE. The separated proteins were incubated with different serum of ESCC patients (29 cases) or healthy controls (28 cases) respectively, and then one of the positive bands in 43 kDa was excised followed by in-gel tryptic digestion. Separated peptides were identified using a high definition mass spectrometry (HDMS). Western blot and immunohistochemical staining (IHC) were used to validate possible candidates.
RESULTS: Successful compartmental protein extraction was demonstrated by specific organelle markers. Serum samples of ESCC patients bound EC0156 cytoplasmic protein, suggesting selective recognition of tumor-associated antigen. 43 kDa protein band showed significantly higher positive binding rate with serum of ESCC patients (41.4%, 12/29) than with serum of healthy individuals (3.6%, 1/28). Five high-confidence proteins were identified from the 43 kDa band using HDMS including phosphoglycerate kinase 1 (PGK1), β-actin, proteasome 26S subunit, S-adenosylhomocysteine hydrolase and hosphoribosylaminoimidazole carboxylase. Immunohistochemistry. Western blot analysis showed that PGK1 was located in both cytoplasm and nucleus, and had a higher expression in cancer tissues (69.23%, 18/26) than in normal esophageal epithelia.
CONCLUSION: The mSERPA strategy is useful for tumor-associated antigen identification. As a new candidate of tumor-associated antigen, PGK1 was over-expressed in ESCC which may play a role in tumorigenesis of ESCC.
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