Background: No effective targeted therapy exists for esophageal squamous cell carcinoma (ESCC), the major cell type of esophageal cancer. The pleiotropic cytokine interleukin (IL)-6 is associated with adverse prognosis of some cancers, and the open reading frame of IL-6 contains an miR-608 microRNA-targeted site. We investigated the correlation of circulating IL-6 levels with prognosis and with the mir608:rs4919510 genetic polymorphism in ESCC.
Methods: A total of 213 patients with primary ESCC were enrolled. Plasma IL-6 levels of ESCC patients were analyzed by enzyme-linked immunosorbent assay (ELISA). The patients' genotypes of mir608:rs4919510 were analyzed using the MassARRAY system, and functional assays were performed by transient overexpression in cells. The cytotoxicity of IL-6 signaling blockers in ESCC cells was analyzed by MTT assay.
Results: We found that plasma IL-6 levels significantly correlated with overall survival (p = 0.019), disease recurrence (p = 0.003), and postoperative complications (p =0.002). Patients with the GG genotype of mir608:rs4919510 had a 4.56-fold increased risk of high expression of IL-6 compared with patients with the CC genotype (odds ratio 4.56, 95% confidence interval 1.87-11.09; p =0.001). Transient overexpression of the miR-608 C (miR-608_C) and G variants (miR-608_G) in cancer cells revealed that the miR-608_G variant was less efficient in regulating the expression of IL-6 compared with miR-608_C. Finally, the IL-6 signaling blocker ruxolitinib exhibited effective cytotoxicity in ESCC cells.
Conclusions: The results of this study provide a novel direction for a biomarker-based targeted therapy for ESCC.