Role of Calponin 2 as a Tumor Inhibitor in Esophageal Cancer

Calponin is an actin filament-associated regulatory protein that can inhibit the activity of myosin-ATPase and stabilize the dynamics of the actin cytoskeleton. Although calponin 2 has been reported to play roles in several cancers, whether it takes part in the progression of esophageal cancer still remains unknown. To explore the pathologic significance of calponin 2 in esophageal squamous cell carcinoma, the expression level of calponin 2 proteins in the tumor tissue of 190 esophageal squamous cell carcinoma patients was examined with immunohistochemistry while the expression level of calponin 2 messenger ribonucleic acid was analyzed by using the data from The Cancer Genome Atlas database. Both the calponin 2 messenger ribonucleic acid and protein level were increasingly expressed in the tumor tissues of esophageal squamous cell carcinoma patients compared with the adjacent non-tumor tissue and correlated negatively with the tumor grade. Patients with higher calponin 2 in the tumor tissue were found to have longer overall survival time. Calponin 2 was shown to be an independent factor influencing the overall survival of the esophageal squamous cell carcinoma patients. Methylation analysis based on MethSurv database revealed a methylation site in the body of calponin 2 gene, which was associated with a better prognosis. Further, in esophageal cancer tumor tissue, calponin 2 gene was found to co-express with genes associated with tight junction and the expression level of calponin 2 was observed to correlate significantly with the number of infiltrating immune cells. These results supported the idea that calponin 2 is involved in esophageal cancer and may function as a tumor inhibitor probably through modulating cancer cells tight junction and tumor immunity.