Abstract: Objective To investigate the expression of MC1R in esophageal squamous cell carcinoma and its correlation with the clinicopathological parameters. Methods We analyzed the expression of MC1R in esophageal cancer based on data from TCGA databse and examined its expression levels using RT-PCR and Western blotting in a human esophageal epithelial cell line BAr-T, human esophageal squamous cell carcinoma cell lines ECA109, KYSE30, KYSE150, KYSE510, TE-1, TE-13, and EC9706, a human gastric cancer cell line SGC7901 and 19 pairs of esophageal squamous cell carcinoma tissues and adjacent tissues. Immunohistochemistry was used to detect MC1R expression levels in 32 pairs of paraffin-embedded sections of esophageal squamous cell carcinoma and adjacent tissues, and the correlation of MC1R expression and the patients' clinicopathological characteristics was analyzed. Results Bioinformatics analysis showed that MC1R was significantly overexpressed in esophageal cancer tissues (P<0.05). MC1R expression was also increased in 5 esophageal squamous cell carcinoma cell lines ECA109, KYSE30, KYSE510, TE-13, EC9706 and the gastric cancer cell line SGC7901 as compared with that in esophageal epithelial cells (P<0.05). Immunohistochemistry revealed significantly increased MC1R expression in esophageal squamous cell carcinoma tissue sections in comparison with the adjacent tissue sections (P<0.05). In patients with esophageal squamous cell carcinoma, a high MC1R expression was detected mainly in those with an old age, positive for middle-thoracic involvement, and with moderately differentiated tumor cells, and showed a correlation with T stage of tumor (P<0.05), but not with the other clinicopathological parameters such as gender, age, degree of cell differentiation, primary tumor site, or TNM stage (P>0.05). Conclusion MC1R is highly expressed in esophageal squamous cell carcinoma and may serve as a molecular biomarker to assist in the diagnosis of esophageal squamous cell carcinoma.

Key words: MC1R; esophageal squamous cell carcinoma; clinicopathological parameters; molecular biomarker