Prosaposin – A plausible biomarker in head and neck squamous cell carcinoma

Objectives Head and Neck Squamous Cell Carcinoma (HNSCC) is one of the leading cancers in developing countries with very high morbidity and mortality. One of the important reasons for the poor outcome is late diagnosis, which is majorly attributed to the non-availability of suitable diagnostic and prognostic biomarkers. In search of suitable biomarkers, we previously identified a number of differentially expressed proteins in the saliva and serum of HNSCC patients. Prosaposin (PSAP) is one of them, which we tried to validate in this current study. Materials and methods Serum PSAP levels were estimated in biopsy-proven HNSCC cases (n = 98) before and after completion of therapy and compared with age and sex-matched healthy volunteers (n = 44). Tissue levels of PSAP were analysed by Immunohistochemistry in the tumour tissues. Effects of downregulation on the tumour hallmarks were analysed by down-regulating PSAP by shRNA in HNSCC cell lines. Results Serum PSAP levels of cases at baseline (median: 2.736 ng/mL) were found to be significantly elevated when compared to healthy controls (median: 2.129 ng/mL) (p = 0.0297*). A significant decrease in PSAP levels was found post-treatment. Cell proliferation, cell migration, cell invasion, and colony formation were found to be significantly reduced with the downregulation of PSAP. However, cell death remained unchanged with the downregulation of PSAP. Conclusion We propose serum PSAP as a possible biomarker in HNSCC patients. Further large-scale clinical studies are warranted to establish serum PSAP as a diagnostic/prognostic marker in HNSCC patients.