Overexpression of microRNA-196b accelerates invasiveness of cancer cells in recurrent epithelial ovarian cancer through regulation of Homeobox A9

Background/Aim: Although microRNAs (miRNAs) are known to influence messenger RNA post-transcriptional control and contribute to human tumorigenesis, little is known about the differences in miRNA expression between primary and recurrent epithelial ovarian cancer (EOC). The purpose of this study was to assess the differential miRNA expression between primary and recurrent EOC and to investigate whether miR-196b could regulate the expression of the Homeobox A9 (HOXA9) gene, and thus affect the invasiveness of cancer cells in recurrent EOC. Materials and Methods: Microarrays were used to generate the expression profiles of 6658 miRNAs from samples of 10 patients with EOC. miRNA expression patterns were compared between primary and recurrent EOC. Aberrantly expressed miRNA, associated genes, and invasion activities were validated by a luciferase assay and an in vitro invasion assay. Results: miRNA microarray analysis identified 33 overexpressed miRNAs (including miR-196b) and 18 under expressed miRNAs in recurrent EOC from 6658 human miRNAs. HOXA9 expression was inversely correlated with miR-196b levels in recurrent EOC. We noted that miR-196b induced ovarian cancer cell invasiveness in recurrent EOC by an in vitro invasion assay. Conclusion: Overexpression of miR- 196b may contribute to invasion activities in recurrent EOC by regulating the HOXA9 gene. Moreover, miR-196b can be a potential biomarker in recurrent EOC.