Proteomic identification of serum biomarkers for head and neck cancer surveillance

Objectives/Hypothesis: Serum protein profiling by SELDI-TOF-MS distinguishes pretreatment and post-treatment samples from patients with head and neck squamous cell cancer (HNSCC) by disease status (disease-free or recurrence) with a high degree of sensitivity and specificity. We sought to identify biomarkers for recurrence with potential utility for surveillance and incorporated 2-D DIGE and MALDI-TOF-MS techniques to overcome the limitations of SELDI-TOF-MS in determining biomarker identity. Methods: Serum samples were collected prospectively from 143 HNSCC patients and analyzed based on disease status following treatment. Results: Recurrent HNSCC occurred in 46 patients. MALDI-TOF-MS following immunodepletion of major plasma proteins followed by 2-D DIGE identified 181 proteins with differential expression between pretreatment and post-treatment samples collected 6 months or more following treatment. Classification by disease status revealed significant differential expression of 16 proteins, with recurrent HNSCC associated with underexpression of kininogen and serine protease inhibitors C-1 inhibitor, kininogen, angiotensinogen, serine/cysteine proteinase inhibitor clade G member 1, and overexpression of thiol-specific antioxidant proteins (TSA), apolipoprotein A1 and proapolipoprotein, and epidermal cytokeratin 2. Conclusions: Serum protein profiling using 2D DIGE/MALDI-TOF-MS identifies proteins with significant differential expression in HNSCC based on disease status. Recurrent HNSCC was associated with underexpression of several protease inhibitors and kininogen, which has antiangiogenic properties, and overexpression of TSA, which is a free radical scavenger, as well as several forms of apolipoprotein A1 that may serve as a carrier molecule but may also indirectly promote tumor survival through kinase activation. This profile is consistent with a more aggressive disease variant and warrants further investigation.