Abstract 3686: Regulatory role cancer stem cells (CSCs)-derived exosomal miRNAs in ovarian cancer growth and progression
Authors: Duzagac Fahriye , Lopez-Berestein Gabriel , Kanlikilicer Pinar , Rodriguez-Aguoya Cristian , Cardenas-Zuniga Roberto , Guven Ummu , Oktem Gulperi , Ozpolat Bulent 
Published: August 2019

Abstract
Ovarian cancer (OC) is the most lethal cancer in all of the gynecological cancers.Despite the recent advancements in the treatment of OC, it remains the seventh most common cancer in women worldwide. Cancer stem cells (CSCs) are a unique cell population described by their ability to indefinitely self-renew, proliferate, initiate, and propagate. Evidence suggest that the interaction between cancer stem cells with their microenvironment play a critical role for cancer progression. Exosomes which are the key players of microenviroment are nano-sized (50-180nm) endosomal pathway-derived vesicles that present in almost all biological fluids.Transporting information via exosomes and exosomal miRNAs is deemed to be the crucial way of intercellular communication that is as essential as the cell-to-cell contact-dependent signaling. As a key regulator of cellular signaling, both normal, and cancer stem cells secrete exosomes to orchestrate diverse autocrine and paracrine functions which alter tumor micro-environment, growth, progression and putative immunological function. There is still not much known about how ovarian cancer stem cells (OCSCs) interact with their tumor microenvironment to promote oncogenic phenotype. Thus, in this study we investigate whether the OCSCs-derived exosomal miRNAs mirror and orchestrate that of the tumor microenvironment and thus could be used diagnostically in ovarian cancer patients.To this end,we evaluated significantly differentially expressed miRNAs between OCSCs exosomes and their cells of origin using the Affymetrix Gene Chip miRNA 4.0 microarrays. Several miRNAs were found to be significantly upregulated in both OCSCs and their exosomes. In addition we found many common up/down regulated miRNAs (miR-103a-3p, miR-20a-5p, miR-125b-5p, miR-17-5p, miR-27a-3p, miR-8075, miR-4487) with the microarray data in which tumor-associated macrophage (TAM) exosomes and their cells of origin were compared. We also found that OCSCs secrete exosomes enriched in miR-103a-3p, which has been shown to increases cancer migration, invasion and angiogenesis and induces polarization of M0 type macrophages toward immunosuppressive M2-type macrophages. In addition TAMs promote cancer stem cell-like properties by enhancing their epithelial–mesenchymal transition capacity. We are currently validating the identified miRs and investigating the role of these miRs in OC cells and CSCs proliferation, migration, invasion and tumor growth. Our findings also indicate that the interaction between TAMs and OCSCs are bidirectional. Overall, our data suggest that OCSCs and OCSCs secreted exosomes may contribute tumor microenvironment especially by regulating TAMs by transferring oncogenic miRs and using them as a progression and invasion tools within tumor microenvironment.
Citation Format: Fahriye Duzagac, Gabriel Lopez-Berestein, Pinar Kanlikilicer, Cristian Rodriguez-Aguoya, Roberto Cardenas-Zuniga, Ummu Guven, Gulperi Oktem, Bulent Ozpolat. Regulatory role cancer stem cells (CSCs)-derived exosomal miRNAs in ovarian cancer growth and progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3686.