Comparative serum proteomic analysis involving liver organ-specific metastasis-associated proteins of nasopharyngeal carcinoma.

Metastasis is the main cause of cancer-related mortality; patients with liver metastases (LM) have the worst prognosis among patients with nasopharyngeal carcinoma (NPC). However, at present, few biomarkers for detecting organ-specific metastasis have been identified. Proteomics, an ultra-sensitive analytical technique, can detect molecular changes before organ-specific metastasis occurs. Analysis with matrix-assisted, laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS), combined with magnetic chemical affinity beads is a new technique for evaluating protein separation. We sought to identify potential liver-specific, metastasis-associated proteomic printing in patients with NPC. We examined 64 serum samples from 50 patients who had pathologically confirmed NPC and 14 who had pathologically confirmed non-NPC with LM using MALDI-TOF-MS with weak cation bead protein chips. During follow-up of at least 37 months (maximum, 176 months) following radiotherapy, we confirmed 16 cases of LM (LM NPC), 16 cases without LM (non-LM NPC) and 18 cases without metastasis (non-M NPC). Using comparison analysis, 4 protein mass peaks, 4155.34, 4194.87, 4210.78 and 4249.56 m/z were identified as liver-specific, metastasis-associated protein peaks in NPC and two of them (4155 and 4249 m/z) met two different statistical criteria in both ClinProt software analyses and discriminant analyses. Models based on the 4 potential serum markers of NPC discriminated between LM NPC, non-LM NPC, non-M NPC and non-NPC LM analyzed with sieved markers. The recognition capability and cross-validation of these models for differentiating the above 4 groups are all approximately 80%. MALDI-TOF-MS combined with tree analysis models may provide a clinical diagnostic platform for detecting potential liver-specific, metastasis-associated proteomic printing in NPC. However, markedly differential proteins still need to be identified.