MicroRNA-544 inhibits esophageal squamous cell carcinoma cell proliferation and enhances sensitivity to cisplatin by repressing E2F transcription factor 5

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies worldwide. MicroRNA (miRNA)-544 is an important cancer-associated RNA that is downregulated in multiple types of cancer. However, the role of miR-544 in ESCC progression remains unknown. In the present study, miR-544 expression level was determined via RT-qPCR in 30 pairs of ESCC and adjacent normal tissues and in a panel of ESCC cell lines. Cell proliferation and cell apoptosis were assessed by MTT and flow cytometry assays. Luciferase reporter assay and western blot analysis were conducted to verify E2F transcription factor 5 (E2F5), an oncogene in ESCC, as a novel target gene of miR-544. The results illustrated that miR-544 is frequently downregulated in ESCC tissues and cell lines. Overexpression of miR-544 in ESCC cells resulted in decreased cell proliferation and increased cell apoptosis. Thus, E2F5 was identified as a target of miR-544, and its expression was negatively correlated with miR-544 expression in clinical ESCC tissues. More importantly, overexpression of miR-544 led to increased sensitivity of ESCC cells to cisplatin, an anticancer drug. Overall, these findings indicate that miR-544 serves as a tumor suppressor by targeting E2F5; thus, miR-544 may be a therapeutic target for the treatment of ESCC.