Abstract
This study examined Sal-like protein (SALL)1 methylation profiles in head and neck squamous-cell carcinoma (HNSCC) patients at diagnosis and follow-up, and evaluated their prognostic significance and value as a biomarker. SALL1 expression was examined in a panel of cell lines by quantitative reverse transcription PCR (qRT-PCR). Promoter methylation was determined by quantitative methylation-specific polymerase chain reaction (qMSP) and was compared to the clinical characteristics of 205 samples. SALL1 promoter methylation was associated with transcriptional inhibition and was correlated with disease recurrence in 31.7% of cases, with an odds ratio of 1.694 (95% confidence interval: 1.093-2.626; P = 0.018) by multivariate Cox proportional hazard regression analysis. SALL1 promoter hypermethylation showed highly discriminatory receiver operator characteristic curve profiles that clearly distinguished HNSCC from adjacent normal mucosal tissue, and was correlated with reduced disease-free survival in early stage T1 and T2 patients (log-rank test, P < 0.001). SALL1 methylation was significantly correlated with the methylation status of both SALL3 and CDH1. This study suggests that CpG hypermethylation is a likely mechanism of SALL1 gene inactivation, supporting the hypothesis that SALL1 might play a role in HNSCC tumorigenesis and could serve as an important biomarker.