Identification of NCCRP1 as an epigenetically regulated tumor suppressor and biomarker for malignant phenotypes of squamous cell carcinoma of the esophagus.

The poor prognosis and increasing incidence of esophageal squamous cell carcinoma (ESCC) highlight the need for identification of novel ESCC-associated molecular events to improve the diagnosis, and treatment of this disease. Non-specific cytotoxic cell receptor protein 1 (NCCRP1) was reported to be abundantly expressed in human squamous epithelium and to be involved in cell proliferation; however, the role of NCCRP1 in ESCC remains unclear. To elucidate the oncological roles of NCCRP1 in ESCC, NCCRP1 expression, DNA methylation, and copy numbers were analyzed in ESCC cell lines. Nine ESCC cell lines demonstrated different NCCRP1 mRNA expression levels and all exhibited hypermethylation of the NCCRP1 promoter, but no copy number loss. Additionally, NCCRP1 expression was determined in 213 surgically resected esophageal tissue samples. NCCRP1 mRNA expression levels were reduced in ESCC tissues compared with corresponding non-cancerous adjacent tissues in 204 (95.8%) patients. Patients in the low NCCRP1 expression group tended to have a higher recurrence rate and a shorter overall survival time compared with those in the high NCCRP1 expression group. Additionally, multivariate analysis revealed that low NCCRP1 expression was an independent prognostic factor (hazard ratio, 1.75; 95% confidence interval, 1.08-2.87; P=0.022). The findings of the current study indicate that NCCRP1 acts as a putative tumor suppressor that is inactivated through promoter hypermethylation, and serves as a promising biomarker to predict postoperative prognosis in ESCC.