Quantitative Serum Proteomics Reveals The Predictive and Prognostic Potential of Clusterin and Gelsolin in Head and Neck Squamous Cell Carcinoma Treated With Radiotherapy

Background Radiotherapy (RT) with concomitant chemotherapy (CTRT) is the standard treatment for advanced head and neck squamous cell carcinoma (HNSCC). Despite advancements in treatment, a significant proportion of patients develop local recurrence and/or metastasis indicating resistance to treatment. Early identification of radio-resistant tumors using predictive and prognostic biomarkers is an important goal. We used a quantitative serum proteomics platform to evaluate the differential expression of proteins in HNSCC patients treated with CTRT. Methods Fifty patients with biopsy-proven, HPV-negative, squamous cell carcinoma of the oropharynx and larynx, undergoing curative CTRT were included in this prospective, IRB-approved study. Serum samples were collected before the start of RT (PreRT), 48 hours after RT (48hrsRT), and 1week after RT (1WeekRT). Patients were classified as “good responders” or “poor responders” based on their clinical outcome at follow-up. Relative quantitation of serum was carried out by iTRAQ to identify differentially expressed proteins. A total of 180–200 proteins were identified, of which twenty proteins showed more than 1.5 fold differential expression. PreRT protein expression levels were compared across good and poor responders to identify proteins with prognostic potential. Differential expression of proteins during RT was analyzed to identify proteins with predictive potential. Finally, twelve proteins were validated using targeted mass spectrometry in ten good and poor responders. Results A 1.5–2.5 fold pre-treatment upregulation of clusterin, gelsolin, extracellular matrix proteins, and proteins of the IGF pathway was observed in poor responders. A 2.0–5.0 fold upregulation of S100 proteins, clusterin, gelsolin, extracellular matrix proteins, IGF1, IGF2, and IGFBP3 was observed in poor responders within 48 hours to 1 week of starting RT. Conclusions The present results are the first report for a panel of twelve potential proteins that would help in early risk stratification and therapeutic prognosis of HNSCC treated with radiotherapy. The significant upregulation of clusterin and gelsolin at PreRT and within 48 hours to 1 week of starting RT, indicates their ability to act as prognostic and predictive markers, respectively. The panel of twelve proteins may facilitate the early identification of patients who are most likely to develop resistance to radiotherapy.