Abstract 763: Exosomal miR-6126 as a novel tumor suppressor in ovarian cancer

Tumor microenvironment has been known to play a key role in cancer by the development of drug resistance, epithelial-mesenchymal transition, metastasis and angiogenesis. There is emerging evidence that cancer originated exosomes may contribute to the tumor microenvironment to promote tumorigenesis. Exosomes are nano-sized vesicles that contain non-coding RNAs such as miRNAs or siRNAs. Non-coding RNAs are involved in the pathogenesis of the majority of cancer and reveals a new layer of complexity in the molecular architecture of tumorigenicity. The purpose of this study is to identify miRNA content of both sensitive and resistant ovarian cancer-cell derived exosomes for the identification of exosomal RNA-mediated tumorigenesis in ovarian cancer. Using miRNA microarray profiling, we identified differentially expressed exosomal miRNAs in three sensitive (Heya8, Skov3, A2780) and resistant (Heya8-MDR, Skov3-TR, A2780-CP20) isogenic ovarian cancer cell lines. miR-6126 was found to be only miRNA significantly up-regulated in all cancer cell exosomes released to tumor microenvironment. In vitro functional assays showed that miR-6126 act as a tumor suppressor by inhibiting proliferation, migration, invasion and tube formation. miR-6126 acts as a novel potential tumor suppressor through targeting integrin beta-1, leading to inhibition of PI3K/AKT and Ras/Raf signaling. In vivo experiments also demonstrated that administration of miR-6126 into the nude mice with established tumors inhibited tumor weight. Immunohistochemistry results showed that miR-6126 treatment inhibits many oncogenic functions such as proliferation and angiogenesis of ovarian cancer. We believe that these findings help the identification of exosomal RNA-mediated tumorigenesis in ovarian cancer. Citation Format: Pinar Kanlikilicer, Mohammed Mohammed H. S. Rashed, Recep Bayraktar, Rahul Mitra, Cristina Ivan, Burcu Aslan, Xinna Zhang, Rodriguez-Aguayo Cristian, Emine Bayraktar, Martin Picher, Bulent Ozpolat, George A. Calin, Anil K. Sood, Gabriel Lopez-Berestein. Exosomal miR-6126 as a novel tumor suppressor in ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 763.