CD47 expression regulated by the miR-133a tumor suppressor is a novel prognostic marker in esophageal squamous cell carcinoma

CD47 inhibits phagocytosis and its overexpression is correlated with poor prognosis in patients with several types of cancer. It has also been reported that CD47 expression in multiple sclerosis is regulated by microRNAs. However, the regulatory mechanism of CD47 in cancer tissues has not been yet clarified. Re-analysis of a public microarray database revealed that miR-133a is downregulated in esophageal squamous cell carcinoma (ESCC). Moreover, in silico algorithms predicted that miR-133a is a regulator of CD47. The purpose of this study was to clarify the clinical significance of CD47 and its regulatory mechanism by miR-133a in ESCC. Quantitative real-time RT-PCR was used to evaluate CD47 and miR-133a expression in 102 cases of curative resected ESCC and adjacent non-cancerous tissue. The regulation of CD47 by miR-133a was examined with precursor miR-133a-transfected cells. A mouse xenograft model was used to investigate the ability of miR-133a to suppress tumor progression. High expression levels of CD47 were associated with lymph node metastasis (P=0.049). Multivariate analysis showed that CD47 expression was an independent prognostic factor (P=0.045). miR-133a expression was significantly lower in cancer tissues compared to adjacent non-cancerous tissues (P<0.001). In vitro assays showed that miR-133a is a direct regulator of CD47.miR-133a significantly inhibited tumorigenesis and growth in vivo. CD47 expression is a novel prognostic marker in ESCC that is directly inhibited by the miR-133a tumor suppressor. This correlation could provide new insight into the mechanism of cancer progression and a promising candidate for target therapy in ESCC.