Objective: To search for novel tumor associated antigens (TAA) in esophageal squamous cell carcinoma (ESCC).
Methods: The proteins extracted from tissues of ESCC were separated by two dimensional polyacrylamide gel electrophoresis and transferred to PVDF membrane. Sera from ESCC patients and healthy individuals were used for primary antibodies for Western blot analysis. The differential spots were excised for trypsin hydrolysis and the tryptic peptides were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The identified TAA of ESCC was validated by immunohistochemical staining (IHC).
Results: Sera from ESCC patients yielded multiple positive spots, and one 28 800 Da protein that exhibited positive reactivity with 60% (12/20) sera of ESCC patients and only 5% (1/20) sera of healthy controls (P<0.01). The 28 800 Da protein was identified as phosphoglycerate mutase 1 (PGAM1) by MALDI-TOF-MS. Immunohistochemical analysis showed that PGAM1 was located in both cytoplasm and nucleus, and had a higher expression in cancer tissues.
Conclusion: PGAM1 maybe a candidate of ESCC.