Promoter methylation of galanin receptors as epigenetic biomarkers for head and neck squamous cell carcinomas

ABSTRACTIntroduction: While remarkable progress has been made in standard treatments for head and neck squamous cell carcinomas (HNSCCs), the long-term survival remains at an unsatisfactory 40–50%. To improve the survival rate, biomarkers for optimal treatment selection and prognostic prediction, as well as novel, low-toxicity treatment strategies, are required. Galanin receptor (GALR) 1 and GALR2 are well-studied tumor suppressors in HNSCCs. Compared with other clinicopathological factors, the epigenetic variants of GALRs have been found to be the most powerful markers to predict the prognosis of HNSCC patients.Areas covered: This review outlines the functions and signaling pathways of GALRs and explains the potential of GALR promoter methylation as a biomarker for HNSCC prognosis. We also summarize recent developments in promoter methylation studies in HNSCC and indicate future directions for GALR promoter methylation studies.Expert commentary: GALR studies have highlighted two major aspects with implic...