miR-145 Inhibits Proliferation and Invasion of Esophageal Squamous Cell Carcinoma in Part by Targeting c-Myc

BACKGROUND: Accumulating evidence has shown that microRNAs (miRNAs) are aberrantly expressed in human esophageal cancer and crucial to tumorigenesis. Herein, we identified the role of miR-145 in esophageal squamous cell carcinoma (ESCC) development in vitro and in vivo. MATERIAL AND METHODS: miR-145 expression was investigated in 40 ESCC samples as well as 5 ESCC cell lines by real-time polymerase chain reaction. Crystal violet and transwell assays were conducted to explore the effects of miR-145 on the proliferation and invasion of human ESCC cell lines, respectively. The impact of overexpression of miR-145 on putative target c-Myc was subsequently confirmed via Western blot. RESULTS: miR-145 expression was frequently downregulated in ESCC specimens and cell lines compared with adjacent normal tissues (p < 0.05). Overexpression of miR-145 suppressed (p < 0.05) ESCC cell proliferation and invasion, as well as the growth of xenograft tumors in mice. Overexpression of miR-145 significantly decreased (p < 0.05) the protein level of c-Myc which has previously been identified as a direct target of miR-145. CONCLUSION: Our results demonstrate that overexpression of miR-145 inhibits tumor growth in part by targeting c-Myc. Our findings revealed that miR-145 may act as a tumor suppressor in ESCC, and its dysregulation may be involved in the initiation and development of human ESCC.