Abstract
Our recent studies of microRNA (miRNA) expression signatures indicated that microRNA-29a (miR-29a) was significantly downregulated in several types of human cancers, suggesting that miR-29a may be a putative tumor-suppressive miRNA in human cancers. The aim of this study was to investigate the functional significance of miR-29a in cervical squamous cell carcinoma (SCC) and to identify novel miR-29a-regulated cancer pathways and target genes involved in cervical SCC oncogenesis and metastasis. Restoration of miR-29a in cervical cancer cell lines (CaSKi, HeLa, ME180 and Yumoto) revealed that this miRNA significantly inhibited cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that heat-shock protein 47 (HSP47), a member of the serpin superfamily of serine proteinase inhibitors and a molecular chaperone involved in the maturation of collagen molecules, was a potential target of miR-29a regulation. Luciferase reporter assays showed that miR-29a directly regulated HSP47. Moreover, silencing of the HSP47 gene significantly inhibited cell migration and invasion in cancer cells and the expression of HSP47 was upregulated in cancer tissues and cervical intraepithelial neoplasia (CIN), as demonstrated by immunostaining. Downregulation of miR-29a was a frequent event in cervical SCC and miR-29a acted as a tumor suppressor by directly targeting HSP47. Recognition of tumor-suppressive miRNA-regulated molecular targets provides new insights into the potential mechanisms of cervical SCC oncogenesis and metastasis and suggests novel therapeutic strategies for treatment of this disease.