Abstract 3121: Hypoxia-related microRNA, miR-199a-3p, displays tumor suppressor function in ovarian cancer

Abstract

Abstract Purpose: Ovarian cancer has the fifth leading cause of death in women in the Western world. At diagnosis, over 60% of all ovarian cancer patients have advanced disease with peritoneal dissemination. During the transcoelomic metastasis of ovarian cancer cells, cells are floating in the peritoneal cavity without vascular supply and exposed in hypoxic conditions, suggesting that hypoxic stimuli affect 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 investigated their function in vitro and in vivo. Methods: miRNA PCR arrays were performed on two ovarian cancer cells (CaOV3 and RMUG-S) cultured under 20% or 1% O2, revealing that miR-199a-3p was one of miRNAs, which expression drastically declined under hypoxia. In order to clarify the relationship between HIF-1α and miR-199a-3p, ovarian cancer cells were transfected with HIF-1A expression vector and the level of miR-199a-3p was determined by RT-real-time PCR. In silico analyses indicated that MET is one of target genes of miR-199a-3p. Thus, miR-199a-3p expression in ovarian cancer cell lines and clinical cancer tissues was assessed by RT-real-time PCR and compared with c-Met expression of those by Western blotting (cell lines) and immunohistochemistry (tissues). To analyze whether miR-199a-3p directly targets the 3′-UTR of MET mRNA, a luciferase reporter assay was performed. 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 anchorage-independent cell proliferation, adhesion and invasion assay. Using an ovarian cancer xenograft model, the therapeutic effect of miR-199a-3p against peritoneal dissemination of cancer cells was investigated. Results: miR-199a-3p expression was not altered by HIF-1A overexpression, suggesting that hypoxia-driven miR-199a-3p change was related to HIF-independent pathway. miR-199a-3p expression was inversely correlated with c-Met expression in both ovarian cancer cell lines and clinical samples. Transfection of precursor miR-199a-3p into SKOV3ip1 cells attenuated c-Met expression followed by the inhibition of phosphorylation of c-Met, ERK and AKT. In luciferase reporter assay, miR-199a-3p directly suppressed MET transcriptional activity. Furthermore, the proliferation, adhesion and invasion of cancer cells were inhibited by the transfection of miR-199a-3p. In an ovarian cancer xenograft model, the enforced expression of miR-199a-3p in SKOV3-13 cells significantly suppressed peritoneal dissemination. Conclusion: Hypoxia-decreased microRNA, miR-199a-3p, remarkably inhibited ovarian cancer progression through the suppression of c-Met. Thus, miR-199a-3p can be suggested as a potential target for new treatment of ovarian cancer. Note: This abstract was not presented at the meeting. Citation Format: Yasuto Kinose, Kenjiro Sawada, Koji Nakamura, Akihiko Yoshimura, Erika Nakatsuka, Seiji Mabuchi, Tadashi Kimura. Hypoxia-related microRNA, miR-199a-3p, displays tumor suppressor function in ovarian cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3121. doi:10.1158/1538-7445.AM2015-3121