[Comparative proteomics of the serum in patients with nasopharyngeal carcinoma: a study with two-dimensional electrophoresis and MALDI-TOF-MS]

Abstract

Objective: To screen the tumor specific antigens of nasopharyngeal carcinoma (NPC) in the serum of the patients.

Methods: Two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was employed to screen the specific biomarkers of NPC in the sera from 42 healthy volunteers, 37 NPC patients with lymph node metastasis and 27 NPC patients without lymphatic metastasis.

Results: After pretreatment including albumin and immunoglobulin (IgG) depletion and desalting, the sera were subjected to 2-DE and image analysis. The differentially expressed protein spots were identified by MALDI-TOF-MS. Sera pretreatment resulted in better repeatability and resolution on the reference gel because of albumin and IgG depletion. From optimized 2-DE gel images, 29 spots indicating differential protein expression were identified by MALDI-TOF-MS to represent 23 proteins. Transferrin, ZNF544 protein, transthyretin, FAD-synthetase and NM23-H1 proteins were down-regulated and 12-lipoxygenase, serum amyloid A1 protein precursor, cytochrome P450, sICAM-1, cathepsin G and lysine-specific histone demethylase 1 were upregulated in the two groups of NPC patients as compared with the healthy group. Increased expressions of 12-lipoxygenase, sICAM-1, cathepsin G and lysine-specific histone demethylase 1 were detected in NPC patients with lymph node metastasis as compared with the patients without lymph node metastasis, but heat shock protein 70 was expressed only in NPC patients with lymph node metastasis.

Conclusion: The 2-DE-based serum proteome analysis can be useful in detecting the protein expression alterations due to carcinogenesis and development of NPC, and the newly discovered biomarkers might help in the diagnosis of NPC.