LAUSR

Background Esophageal squamous cell carcinoma (ESCC) is a highly lethal and aggressive tumor. Our previous study revealed that tropomyosin 3 (TPM3) is up-regulated in the late stage of ESCC and promotes epithelial-mesenchymal transition (EMT) via MMP2/MMP9. However, we have not yet explored the upstream regulator of TPM3. In this study, miR-107, a microRNA molecule, was predicted as an inhibitor targeting TPM3, and in vivo and in vitro experiments confirmed this hypothesis. Methods Western blot and fluorescence quantitative polymerase chain reaction (qPCR) were applied to analyze the expression of miR-107 and TPM3. Flow cytometry, cell counting kit-8 (CCK8) assay, wound-healing assay, colony formation assay, transwell assay, and a BALB/c nude mouse (male, 8 weeks old, 20±2 g) model were used to detect the function of miR-107 and TPM3 in ESCC. Dual-luciferase assay was used to analyze the suppressed TPM3 expression induced by miR-107. Rescue experiments were also conducted in our research. Results The cell and nude mouse models verified that TPM3 promotes proliferation, invasion and metastasis, and inhibits apoptosis, which is the opposite effect of miR-107 in ESCC. Meanwhile, the expression of TPM3 was up-regulated in the ESCC sample and cell lines, and miR-107 was down-regulated correspondingly. Dual-luciferase detection confirmed that miR-107 decreased the expression of TPM3 by targeting the 3’-untranslated region (3’-UTR) at the end of the TPM3 transcript. Further experiments verified that TPM3 could rescue the tumor suppression effect derived from miR-107. Conclusions MiR-107 negatively regulates TPM3 expression and plays a tumor suppression role in ESCC.