MiR-143-3p functions as a tumor suppressor by regulating cell proliferation, invasion and epithelial-mesenchymal transition by targeting QKI-5 in esophageal squamous cell carcinoma.

Background: Dysregulation of microRNAs (miRNAs) have been demonstrated to contribute to carcinogenesis. MiR-143-3p has been identified to function as a tumor suppressor in several tumors, but the role of miR-143-3p in esophageal squamous cell carcinoma (ESCC) has not been intensively investigated. Our aim was to evaluate the potential role of miR-143-3p in the progression of ESCC.

Methods: The expression levels of miR-143-3p and QKI-5 protein were measured in 80 resected ESCC tumor specimens and the clinicopathological significance of these levels determined. We also investigated the role of miR-143-3p in the regulation of QKI-5 expression in ESCC cell lines both in vivo and in vitro.

Results: MiR-143-3p levels were decreased in ESCC clinical samples and low expression of miR-143-3p was significantly associated with poor prognosis in ESCC patients. Ectopic expression of miR-143-3p suppressed proliferation and induced apoptosis in ESCC cells both in vivo and in vitro. Ectopic expression of miR-143-3p also reduced the metastatic potential of cells by selectively regulating epithelial-mesenchymal transition regulatory proteins. Furthermore, QKI-5 isoform was upregulated in ESCC tissues and was a direct target of miR-143-3p. Lastly, re-introduction of QKI-5 expression abrogated the inhibitory effects of miR-143-3p on ESCC cell proliferation and motility.

Conclusions: Our results demonstrate that miR-143-3p acts as a tumor-suppressor by targeting QKI-5 in ESCC, suggesting that miR-143-3p is a potential therapy for the treatment of ESCC.