DCLK1 inhibition attenuates tumorigenesis and improves chemosensitivity in esophageal squamous cell carcinoma by inhibiting β-catenin/c-Myc signaling.

Doublecortin-like kinase 1 (DCLK1) is involved in tumorigenesis, tumor growth and metastasis, and epithelial-to-mesenchymal transition in many digestive tract tumors. It is reportedly highly expressed in Barrett's esophagus and esophageal adenocarcinoma, but its effects on the occurrence and progression of esophageal squamous cell carcinoma (ESCC) remain unclear. In this study, real-time PCR and western blot analysis confirmed significant upregulation of DCLK1 expression in human ESCC tissues and cell lines. CCK-8 assay showed that transfection with siRNA against DCLK1 (si-DCLK1) markedly inhibited cell proliferation and colony formation in the ESCC cell lines Eca109 and TE1. Transwell assay revealed that si-DCLK1 transfection inhibited the migratory and invasive capacities of Eca109 and TE1 cells. Moreover, si-DCLK1 increased the chemosensitivity of these cells to cisplatin, as indicated by inhibited cell viability and colony formation, and increased ROS and apoptosis in cisplatin-treated cells. Western blot assay revealed that expression of nuclear β-catenin and c-Myc was significantly increased in ESCC tissues and that si-DCLK1 markedly downregulated nuclear β-catenin and c-Myc in Eca109 cells. Treatment with lithium chloride, an activator of β-catenin signaling, partially abolished the si-DCLK1-induced inhibition of proliferation, migration, invasion, and chemoresistance of ESCC cells. These findings suggest that knockdown of DCLK1 may inhibit the progression of ESCC by regulating proliferation, migration, invasion, and chemosensitivity via suppressing the β-catenin/c-Myc pathway, supporting a promising therapeutic target against ESCC.