Abstract 4361: Hypoxia-related microRNA, miR-199a-3p, inhibits ovarian cancer progression through the suppression of c-Met expression
Authors: Yasuto Kinose, Kenjiro Sawada, Koji Nakamura, Seiji Mabuchi, Ken-ichirou Morishige, Tadashi Kimura
Journal: Cancer Research (2014)

Abstract Purpose: Ovarian cancer has the highest mortality rate of all gynecologic tumors. It is often diagnosed at an advanced stage after tumor cells are disseminated within the peritoneal cavity. During the dissemination of ovarian cancer cells, cells are floating in the peritoneal cavity without vascular supply and exposed in hypoxic conditions, suggesting that hypoxic stimuli affect ovarian cancer cell behavior and the cells acquire more aggressive malignancy potential. In this study, we screened miRNAs which expression were altered under hypoxic condition and performed functional analysis of those in vitro and in vivo. Methods: miRNA PCR arrays were performed using two ovarian cancer cells (CaOV3, RMUG-S) incubated under 20% or 1% O2. miR-199a-3p, which expression decreased under hypoxic conditions, was extracted. In silico analyses led us to consider MET is one of the target genes of miR-199a-3p. Therefore, we determined to analyze the effect of miR-199a-3p on ovarian cancer cells. The expression of miR-199a-3p in various ovarian cancer cell lines was examined by RT-real-time PCR and the expression of c-Met was examined by Western blotting. In order to investigate whether miR-199a-3p directly targets the 3′-UTR of MET mRNA, a luciferase reporter assay was performed. Using clinical paraffin tissues, only the tumor part was collected by a laser capture microdissection and RNA extracted. The expression of miR-199a-3p was examined by miRNA RT-PCR assays and compared with c-Met protein expression by immunohistochemistry. The effect of miR-199a-3p on c-Met expression as well as its downstream signaling was examined by the transfection of precursor miR-199a-3p. The inhibitory effect of miR-199a-3p on ovarian cancer cells was analyzed through in vitro cell proliferation, adhesion assay and invasion assay. Using a xenograft model, the inhibitory effect of miR-199a-3p against peritoneal dissemination of ovarian cancer cells was analyzed. Results: miR-199a-3p expression was inversely correlated with c-Met expression in ovarian cancer cells and clinical samples. Transfection of precursor miR-199a-3p into SKOV3ip1 cells reduced c-Met expression followed by the inhibition of phosphorylation of c-Met, ERK and AKT. Accordingly, the proliferation, adhesion and invasion of cancer cells were inhibited by the transduction of miR-199a-3p. In luciferase reporter assay, miR-199a-3p directly suppresses MET transcriptional activity. In an ovarian cancer xenograft model, the enforced expression of miR-199a-3p in SKOV3-13 cells significantly suppressed peritoneal dissemination. Conclusion: Hypoxia related microRNA, miR-199a-3p, drastically inhibits ovarian cancer progression through the down-regulation of c-Met expression. miR-199a-3p can be suggested as a potential target for treating ovarian cancer dissemination. Citation Format: Yasuto Kinose, Kenjiro Sawada, Koji Nakamura, Seiji Mabuchi, Ken-ichirou Morishige, Tadashi Kimura. Hypoxia-related microRNA, miR-199a-3p, inhibits ovarian cancer progression through the suppression of c-Met expression. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4361. doi:10.1158/1538-7445.AM2014-4361