Exosomes In Ovarian Cancer Research Articles

Construction of an exosome-associated miRNA-mRNA regulatory network and validation of FYCO1 and miR-17-5p as potential biomarkers associated with ovarian cancer.

The occurrence and development of several human physiological processes are significantly influenced by the competing endogenous RNA (ceRNA) network. The aim of the present study was to construct a microRNA (miRNA)-mRNA network associated with exosomes in ovarian cancer (OV), and experimental validation of key target genes. By exploring the Gene Expression Omnibus (GEO) database, we analyzed the RNAs from 226 samples to identify differentially expressed miRNAs (DEMs) and genes (DEGs) that showed differential expression as OV progressed. Subsequently, we conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses on the DEGs. Furthermore, we constructed a miRNA-mRNA network that pertains to exosomes in OV using DEMs and DEGs. Moreover, we validated the expression levels of mRNAs in the miRNA-mRNA network using Gene Expression Profiling Interactive Analysis (GEPIA2). Ultimately, luciferase reporter assay was used to identify the potential target relationship between FYVE and coiled-coil domain containing 1 (FYCO1) and miRNAs. Our analysis screened a total of 14 DEMs and 101 DEGs, and the DEGs were mainly enriched in DNA replication or repair, amino acid biosynthesis and carbon metabolism. Furthermore, a miRNA-mRNA network was constructed including 3 miRNAs (hsa-miR-17-5p, hsa-miR-20b-5p and hsa-miR-20a-5p) and 2 mRNAs, FYCO1 and purine rich element binding protein A (PURA). Finally, the 2 mRNAs in this miRNA-mRNA network were verified by GEPIA2 using The Cancer Genome Atlas (TCGA) database. Among them, only FYCO1 showed significant different expression of mRNA in OV and normal tissue, while the prognosis of FYCO1 in OV remains controversial due to different database. Interestingly, FYCO1 was identified as the target of hsa-miR-17-5p. By constructing a novel network of miRNA-mRNA, we can gain new understanding of the molecular mechanisms that drive exosomes in OV. Targeting FYCO1, which originates from exosomes, may hold promise as a diagnostic marker for OV.

Colorimetric aptasensor based on temporally controllable light-stimulated oxidase-mimicking fluorescein for the sensitive detection of exosomes in mild conditions.

Analysis of exosomes provides important information for rapid and non-invasive screening of tumors. However, sensitive and convenient detection of exosomes remains technically challenging to date. Herein, a colorimetric aptasensor based on the light-stimulated oxidase-mimicking activity of FITC was constructed for detecting ovarian cancer (OC) exosomes. The aptasensor contained an EpCAM aptamer to capture OC exosomes. Cholesterol and fluorescein (FITC) were used to modify either end of the DNA (DNA anchor). The DNA anchor could combine with exosomes through a hydrophobic reaction between cholesterol and the lipid membrane. FITC oxidized 3,3',5,5'-tetramethylbenzidine (TMB) under a 365 nm LED light source in a temporally controllable manner under mild conditions, causing the solution to change from colorless to blue, and the corresponding UV-vis absorbance increased. Based on this principle, the exosomes were qualitatively analyzed by observing the color change with the naked eye. In parallel, the exosome concentration was also detected using UV-vis spectrophotometry. The linear range was from 2 × 105 to 100 × 105 particles per mL with a limit of detection of 1.77 × 105 particles per mL. The developed aptasensor also exhibited favorable selectivity and could discriminate the exosomes from OC cells and normal cells. Besides, the receiver operating characteristic (ROC) curve demonstrates that it is possible to distinguish between patients with OC and healthy donors (HDs) using exosomes as the biomarker. Our technology may expand the applications of DNA-based detection method-enabled OC diagnostic tools.

Comparative assessment of the exosomal tumor-associated microRNA levels in blood plasma and ascitic fluid in ovarian cancer patients

Introduction. Ovarian cancer (OC) is one of the malignant neoplasms of the female reproductive system with a high mortality rate. Currently used tumor markers of this pathology do not have high sensitivity and specificity. In this regard, promising areas of molecular oncology are the study of the mechanisms of carcinogenesis of OC and the search for new biomarkers of liquid biopsy for early non-invasive diagnosis of neoplasms. It is known that tumor cells actively secrete exosomes into the extracellular space, which include biologically active molecules involved in carcinogenesis and claiming to be diagnostic markers. It was previously shown that microRNA-24 (miR-24) and microRNA-101 (miR-101) are transported as part of exosomes in OC and are involved in the degradation of the extracellular matrix, stromal remodeling, angiogenesis, and cancer cell motility.Aim. To evaluate the representation and diagnostic significance of miR-24 and miR-101 in plasma exosomes and ascitic fluid of OC patients.Materials and methods. The study included blood and ascitic fluid samples from OC patients (n = 20) and blood samples from healthy women (n = 19). The exosomal nature of the vesicles was confirmed by transmission electron microscopy, nanotracing analysis, and flow cytometry. After isolation of exosomal RNA, the relative level of miRNA was determined using reverse transcription and real-time polymerase chain reaction.Results. The highest concentration of exosomes was found in the ascitic fluid of OC patients, while the concentration of exosomes in the blood plasma of these patients was significantly higher than in healthy women. Relative levels of miR-24 and miR-101 in exosomes of blood plasma of healthy women were significantly higher than in exosomes of blood plasma and ascitic fluid of OC patients; at the same time, the levels of these miRNAs in exosomes of plasma and ascitic fluid of patients did not differ significantly.Conclusion. The results obtained confirm the promise of exosomal miR-101 and miR-24 for the diagnosis of OC by liquid biopsy.

The diagnostic and therapeutic prospects of exosomes in ovarian cancer.

Exosomes are nano-sized vesicles derived from the endosomal system and are involved in many biological and pathological processes. Emerging evidence has demonstrated that exosomes with cell-specific constituents are associated with the tumorigenesis and progression of ovarian cancer. Therefore, exosomes derived from ovarian cancers can be potential diagnostic biomarkers and therapeutic targets. In this review, we briefly present the biological characteristics of exosomes and the recent advances in isolating and detecting exosomes. Furthermore, we summarise the many functions of exosomes in ovarian cancer, hoping to provide a theoretical basis for clinical applications of exosomes in the diagnosis and treatment of ovarian cancer.

Role of Exosomes in the Invasion and Metastasis of Ovarian Cancer and Application Potential of Clinical Diagnosis and Treatment.

Ovarian cancer is a highly lethal form of cancer in females, largely due to extensive metastases that often accompany the initial diagnosis. Exosomes are microvesicles size from 30 to 100nm, which can be secreted by most cells. These special extracellular vesicles play a vital role in the metastasis of ovarian cancer. In this study, we conducted a comprehensive review of current research pertaining to the role of exosomes in ovarian cancer, utilizing the PubMed® and Web of Science databases. Our review highlights the progress in elucidating the mechanisms by which exosomes facilitate ovarian cancer progression. Additionally, we discuss the potential of exosomes as a novel therapeutic target for ovarian cancer treatment. Overall, our review provides valuable insights into the current state of research on exosomes in ovarian cancer therapy.

The Roles of Exosomes in Ovarian Cancer Chemo-resistance.

As common gynecological oncology, ovarian cancer has a high fatality rate and poor overall survival, mainly because of nonspecific symptoms in the early stages and chemotherapy resistance. Exosomes, nano-sized vesicles secreted by almost all types of cells, carry valuable commodities such as proteins, lipids, enzymes, mRNAs, and miRNAs between cells. They take part in remodeling the tumor microenvironment, promoting tumor angiogenesis and metastasis, and regulating immune metastasis and chemotherapy resistance in ovarian cancer. Previous studies have reported that exosomes could transfer chemotherapy resistance from drug-resistant tumor cells to sensitive ones by delivering proteins and miRNAs. Also, exosomes are involved in chemotherapy resistance by transferring multidrug-resistance-related transporters, decreasing apoptosis, promoting epithelial-to-mesenchymal transition, and changing signal transduction pathways. Furthermore, they play a significant role in early detection, chemotherapy efficacy evaluation, and treatment of ovarian cancer. Exosomes are applied as chemotherapeutic delivery vehicles and therapeutic targets to inhibit anti-tumor immune responses. In addition, exosomes can be developed for cancer immunotherapy because of their immunomodulatory potential. Therefore, the article reviews the latest research progress of exosomes in ovarian cancer to elaborate on the mechanisms of exosome-mediated chemotherapy resistance in ovarian cancer patients and provide a forecast on their clinical therapeutic potential in improving chemotherapy sensitivity.

Laminins in tumor-derived exosomes upregulated by ETS1 reprogram omental macrophages to promote omental metastasis of ovarian cancer

Tumor-derived exosomes participate in omental metastatic colonization of ovarian cancer by inducing an adaptive response in the tumor microenvironment. However, cell–cell communication via exosomes between primary tumor cells and the microenvironment of distant omentum and the mechanism of pre-metastatic niche formation are poorly understood. Here, we demonstrated that ETS1-overexpressing ovarian cancer cells secreted larger exosomes with higher laminin levels. In addition, ovarian cancer exosomes could be taken up by omental macrophages through integrin and laminin interaction. Compared with control exosomes, exosomes derived from ETS1-overexpressing ovarian cancer cells (LV-ETS1 Exos) stimulated the polarization of more macrophages toward the M2 phenotype (CD163 marker), as well as the production of more CXCL5 and CCL2 in macrophages, via integrin αvβ5/AKT/Sp1 signaling. In vivo experiments showed that LV-ETS1 Exos promoted omental metastasis of ovarian cancer by mediating the tumor-promoting effect of macrophages, which could be neutralized by integrin ανβ5 inhibitor cilengitide. These results indicated that ETS1 could drive ovarian cancer cells to release exosomes with higher laminin levels, thereby accelerating the exosome-mediated pro-metastatic effects of omental macrophages via the integrin αvβ5/AKT/Sp1 signaling pathway, and the integrin ανβ5 inhibitor cilengitide could inhibit omental metastasis of ovarian cancer driven by tumor-derived exosomes.

Exosomes released from cisplatin-resistant ovarian cancer cells modulate the reprogramming of cells in tumor microenvironments toward the cancerous cells

Exosomes released from cancer cells are involved in the reorganization of the tumor microenvironment which is the essential aspect of cancer pathogenesis. The intercommunications between cancer cells and diverse cell types in the microenvironment are accomplished by exosomes in ovarian cancer. Internalization pathway, intracellular fate, and biological functions in recipient cells mediated by exosomes released from cisplatin-resistant A2780cis have been studied. Also, histopathological evaluation of tumor, ovary, liver tissues and lymph nodes in vivo studies have been performed. The recipient cells internalized the exosomes via active uptake mechanisms, as shown by confocal microscopy. However, inhibitor studies and flow cytometry analysis showed that each recipient cell line used different uptake pathways. Also, confocal microscopy imaging indicated that the internalized exosomes trapped in the endosomes or phagosomes were distributed to the different cellular compartments including ER, Golgi, and lysosome. The transfer of exosomal oncogenic cargo into the cells modified the intracellular signaling of recipient cells including invasion and metastasis by Boyden-Chamber assay, proliferation by ATP analysis, epithelial-mesenchymal transition (EMT) markers at protein and mRNA levels by western blotting and real-time PCR, and protein kinases in the phospho-kinase array. This remodeling contributed to the initiation of carcinogenesis in ovarian epithelial and peritoneal mesothelial cells, and the progression of carcinogenesis in ovarian cancer cells. In addition, intraperitoneal tumor model studies show that exosomes released from cisplatin-resistant A2780cis cells may play role in the enlargement of lymph nodes, and tumor formations integrated with the liver, attached to the stomach and in the ovarian tissues.

Analysis of Competitive Endogenous Mechanism and Survival Prognosis of Serum Exosomes in Ovarian Cancer Patients Based on Sequencing Technology and Bioinformatics.

Background: We determined the competitive endogenous in serum exosomes of ovarian cancer patients via sequencing technology and raw signal analysis. We performed an in-depth study of the potential mechanisms of ovarian cancer, predicted potential therapeutic targets and performed survival analysis of the potential targets. Methods: Serum exosomes from three ovarian cancer patients were used as the experimental group, serum exosomes from three patients with uterine fibroids were used as the control group, and whole transcriptome analysis of serum exosomes was performed to identify differentially expressed long noncoding RNAs (lncRNAs) and mRNAs in ovarian cancer. The miRcode database and miRNA target gene prediction website were used to predict the target genes. Cytoscape software was used to generate a competing endogenous RNA (ceRNA) network of competitive endogenous mechanism of serum exosomes in ovarian cancer, and the R language was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the target genes. Finally, the TCGA website was used to download clinical and expression data related to ovarian cancer, and the common potential target genes obtained previously were analyzed for survival. Results: A total of 117 differentially expressed lncRNAs as well as 513 differentially expressed mRNAs (p < 0.05, |log2 fold change (FC)|≥ 1.0) were obtained by combining sequencing data and raw signal analysis, and 841 predicted target genes were reciprocally mapped by combining the data from the miRcode database and miRNA target gene prediction website, resulting in 11 potential target genes related to ovarian cancer (FGFR3, BMPR1B, TRIM29, FBN2, PAPPA, CCDC58, IGSF3, FBXO10, GPAM, HOXA10, and LHFPL4). Survival analysis of the above 11 target genes revealed that the survival curve was statistically significant (p < 0.05) for HOXA10 but not for the other genes. Through enrichment analysis, we found that the above target genes were mainly involved in biological processes such as regulation of transmembrane receptor protein kinase activity, structural molecule activity with elasticity, transforming growth factor-activated receptor activity, and GABA receptor binding and were mainly enriched in signaling pathways regulating stem cell pluripotency, bladder cancer, glycerolipid metabolism, central carbon metabolism of cancer, and tyrosine stimulation to EGFR in signaling pathways such as resistance to enzyme inhibitors. Conclusions: The serum exosomal DIO3OS-hsa-miR-27a-3p-HOXA10 competitive endogenous signaling axis affects ovarian cancer development and disease survival by targeting dysregulated transcriptional pathways in cancer.

Pathophysiological Role and Potential Therapeutic Exploitation of Exosomes in Ovarian Cancer.

Exosomes are extracellular vesicles involved in several biological and pathological molecules and can carry many bioactive materials to target cells. They work as important mediators of cell-cell communication and play essential roles in many diseases, especially in cancer. Ovarian cancer is one of the most common gynecological malignancies. Most patients are diagnosed at advanced stages involving widespread peritoneal dissemination, resulting in poor prognosis. Emerging evidence has shown that exosomes play vital roles throughout the progression of ovarian cancer. Moreover, the development of engineered exosome-based therapeutic applications— including drug delivery systems, biomolecular targets and immune therapy—has increased drastically. Herein, we review the functional features of exosomes in ovarian cancer progression and the therapeutic application potential of exosomes as novel cancer treatments.

Liquid biopsy in ovarian cancer.

Ovarian cancer has the worst survival rate because it is typically diagnosed at advanced stage. Despite treatment, the disease commonly recurs due to chemo-resistance. Liquid biopsy, based on minimally invasive blood tests, has the advantage of following tumor evolution in real time, offering novel insights on cancer prevention and treatment. Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating cell-free microRNAs (cfmiRNAs) and circulating exosomes represent the major components of liquid biopsy. In this chapter, we provide an overview of recent research on CTCs, ctDNA, cfmiRNAs and exosomes in ovarian cancer. We also focus on the clinical value of liquid biopsy in early diagnosis, prognosis, treatment response, as well as screening in the general population.

MicroRNA profiling of plasma exosomes from patients with ovarian cancer using high-throughput sequencing.

To the best of our knowledge, the microRNA (miR/miRNA) expression profile of plasma exosomes in ovarian cancer has not been previously studied. The aim of the present study was to investigate the practicality of using plasma exosomal miRNAs as novel serological biomarkers of ovarian cancer. In the study, exosome-like vesicles were purified from the plasma of patients with ovarian cancer and healthy women using differential centrifugation. The purified vesicles, ranging from 50–100 nm in size, were identified as exosomes by transmission electron microscopy and western blotting. High-throughput sequencing demonstrated that 65 known miRNAs, 34 of which were upregulated and 31 downregulated, were differentially expressed between patients with ovarian cancer and healthy women (P<0.05; fold change ≥2). The miRNA expression levels of hsa-miR-106a-5p, hsa-let-7d-5p and hsa-miR-93-5p were significantly increased, whereas hsa-miR-122-5p, hsa-miR-185-5p and hsa-miR-99b-5p expression levels were significantly decreased in the exosomes of patients with ovarian cancer compared with those in the healthy controls. Additionally, the miRNA expression levels of plasma hsa-miR-93-5p were significantly increased in patients with ovarian cancer compared with those in the healthy controls, while the plasma expression levels of hsa-miR-122-5p and hsa-miR-99b-5p were significantly decreased in patients with ovarian cancer compared with those in the healthy controls. Overall, the present study identified plasma and exosomal miRNAs with dysregulated expression in patients with ovarian cancer compared with that in healthy controls, and the differentially expressed miRNAs may have potential as diagnostic and prognostic targets for the treatment of patients with ovarian cancer.

Exosomal miRNA confers chemo resistance via targeting Cav1/p-gp/M2-type macrophage axis in ovarian cancer.

BackgroundCirculating miRNAs are known to play important roles in intercellular communication. However, the effects of exosomal miRNAs on cells are not fully understood.MethodsTo investigate the role of exosomal miR-1246 in ovarian cancer (OC) microenvironment, we performed RPPA as well as many other in vitro functional assays in ovarian cancer cells (sensitive; HeyA8, Skov3ip1, A2780 and chemoresistant; HeyA8-MDR, Skov3-TR, A2780-CP20). Therapeutic effect of miR-1246 inhibitor treatment was tested in OC animal model. We showed the effect of OC exosomal miR-1246 uptake on macrophages by co-culture experiments.FindingsSubstantial expression of oncogenic miR-1246 OC exosomes was found. We showed that Cav1 gene, which is the direct target of miR-1246, is involved in the process of exosomal transfer. A significantly worse overall prognosis were found for OC patients with high miR-1246 and low Cav1 expression based on TCGA data. miR-1246 expression were significantly higher in paclitaxel-resistant OC exosomes than in their sensitive counterparts. Overexpression of Cav1 and anti-miR-1246 treatment significantly sensitized OC cells to paclitaxel. We showed that Cav1 and multi drug resistance (MDR) gene is involved in the process of exosomal transfer. Our proteomic approach also revealed that miR-1246 inhibits Cav1 and acts through PDGFβ receptor at the recipient cells to inhibit cell proliferation. miR-1246 inhibitor treatment in combination with chemotherapy led to reduced tumor burden in vivo. Finally, we demonstrated that when OC cells are co-cultured with macrophages, they are capable of transferring their oncogenic miR-1246 to M2-type macrophages, but not M0-type macrophages.InterpretationOur results suggest that cancer exosomes may contribute to oncogenesis by manipulating neighboring infiltrating immune cells. This study provide a new mechanistic therapeutic approach to overcome chemoresistance and tumor progression through exosomal miR-1246 in OC patients.

Exosomal Mirna Confers Chemo Resistance Via Targeting Cav1/p-gp/M2-Type Macrophage Axis in Ovarian Cancer

Circulating miRNAs are known to play important roles in intercellular communication.However, the effects of exosomal miRNAs on cells are not fully understood. In this study, substantial expression of oncogenic miR-1246 in sensitive as well as chemoresistant (paclitaxel and multidrug) ovarian cancer (OC) exosomes was found. We showed that Cav1 gene, which is the direct target of miR-1246, is involved in the process of exosomal transfer. A significantly worse overall prognosis were found for OC patients with high miR-1246 and low Cav1 expression based on TCGA data. miR-1246 expression were significantly higher in paclitaxel-resistant OC exosomes than in their sensitive counterparts. Overexpression of Cav1 and anti-miR-1246 treatment significantly sensitized OC cells to paclitaxel. We showed that Cav1 and multi drug resistance (MDR) gene is involved in the process of exosomal transfer. Our proteomic approach also revealed that miR-1246 inhibits Cav1 and acts through PDGFI² receptor at the recipient cells to inhibit cell proliferation. miR-1246 inhibitor treatment in combination with chemotherapy led to reduced tumor burden in vivo. Finally, we demonstrated that when OC cells are co-cultured with macrophages, they are capable of transferring their oncogenic miR-1246 to M2-type macrophages, but not M0-type macrophages. Our results suggest that cancer exosomes may contribute to oncogenesis by manipulating neighboring infiltrating immune cells. This study provide a new mechanistic therapeutic approach to overcome chemosensitization and tumor progression through exosomal miR-1246 in OC patients. Funding: This study was funded by the NIH Common Fund (UH3 TR000943), through the Office of Strategic Coordination/Office of the NIH Director and MD Anderson’s Cancer Center Support Grant (CCSG) (CA016672) to G. Lopez-Berestein, A.K. Sood, G.A. Calin,, the American Cancer Society Research Professor Award to A.K. Sood, and The Center for RNA Interference and Non-Coding RNA to G.A. Calin, A.K. Sood, and G. Lopez-Berestein and CA166228 from the National Cancer Institute of the NIH to MLG. Declaration of Interest: We have no conflicts of interest to disclose. Ethical Approval: All animal work was approved by the Institutional Animal Use and Care Committee of MD Anderson.

Tumor-derived exosomes in ovarian cancer - liquid biopsies for early detection and real-time monitoring of cancer progression.

Ovarian cancer usually has a poor prognosis because it predominantly presents as high stage disease. New approaches are required to develop more effective early detection strategies and real-time treatment response monitoring. Nano-sized extracellular vesicles (EVs, including exosomes) may provide an approach to enrich tumor biomarker detection and address this clinical need. Exosomes are membranous extracellular vesicles of approximately 100 nm in diameter that have potential to be used as biomarkers and therapeutic delivery tools for ovarian cancer. Exosomal content (proteins and miRNA) is often parent cell specific thus providing an insight or “fingerprint” of the intracellular environment. Furthermore, exosomes can aid cell-cell communication and have the ability to modify target cells by transferring their content. Additionally, via the capacity to evade the immune system and remain stable over long periods in circulation, exosomes have potential as natural drug agents. This review examines the potential role of exosomes in diagnosis, drug delivery and real-time monitoring in ovarian cancer.

TGFβ1 in fibroblasts-derived exosomes promotes epithelial-mesenchymal transition of ovarian cancer cells.

Cancer-associated fibroblasts (CAF), a major component of the tumor microenvironment, play an important role in interacting with neoplastic cells to promote ovarian cancer progression. Exosomes are nano-sized vesicles that mediate the cross-talk between different cell types. An increasing number of studies have focused on the fact that tumor cell-derived exosomes influence stromal cells. However, the mechanism by which CAF-derived exosomes modulate cancer cells in ovarian cancer remains obscure. To investigate the role of CAF exosomes in ovarian cancer, we examined the exosomal content of paired primary, metastatic and normal fibroblasts from seven stage IIIC ovarian cancer patients by ELISA. We found that in ovarian CAF-derived exosomes, TGFβ1 was upregulated compared to normal omentum fibroblasts (NOF). Exosomes derived from CAF were taken up by ovarian SKOV-3 and CAOV-3 cell lines during co-culture and induced malignant behaviors in cancer cells, including an enhanced migration and invasion ability and the promotion of epithelial-mesenchymal transition (EMT) by activating the SMAD signaling pathway. Our results indicate that the role of TGFβ1 in CAF exosomes triggers ovarian cancer cells into a more aggressive phenotype, suggesting that targeting CAF exosomes could be a potential treatment in ovarian cancer.

MiR-101 inhibits ovarian carcinogenesis by repressing the expression of brain-derived neurotrophic factor.

Ovarian cancer is one of the most lethal malignant gynecological tumors as a result of difficulties in early‐stage detection and a lack of effective treatments for patients with advanced or recurrent cancer. In the present study, we aimed to explore whether some of the microRNA (miRNA) content of serum might be related to ovarian cancer, as well as the role of these miRNAs and their intercellular transport via exosomes in ovarian cancer. We first detected the expression of six candidate miRNAs in ovarian cancer tissues and adjacent nontumor ovarian samples from 36 patients and confirmed the altered expression of four miRNAs. The level of these six candidate miRNAs was also examined in exosomes from patient serum samples. Only the level of miR‐101 was altered in both ovarian tissue samples and serum exosomes. After prediction using online bioinformatics tools and confirmation by dual‐luciferase assay and immunoblotting, we identified that miR‐101 can repress the expression of brain‐derived neurotrophic factor by targeting its 3′‐UTR. Using Transwell assays, we examined the effect of miR‐101 on migration and invasion capacity of ovarian cancer cells. The results indicated that the reduction of miR‐101 is mostly related to significant enhanced ovarian cancer cell migration. Thus, the results of the present study indicate that miR‐101 content in serum exosomes has potential as a marker for diagnosis of ovarian cancer and that miR‐101 mimics are potential therapeutic drugs for the treatment of ovarian cancer.

Abstract 1988: Exosome-mediated ovarian cancer tumorigenesis mediated by miR1246/Rb/Cav1 axis

Abstract Exosomes are secreted from many cell types and play an important role in the tumor microenvironment. The most impressive breakthrough in exosomes research was that they contain the genetic material of the host cell. However, whether cancer cells use their exosomes to transfer their oncogenic material to recipient cells, or to get rid of their tumor suppressor material is not well understood. We previously identified that miR-1246 was hundreds of folds higher expressed in six different ovarian cancer exosomes compared to their originating cells. Here, we showed that miR-1246 co-localized in the exosomes in ovarian cancer cells. miR-1246 act as an oncogenic miRNA and the levels were elevated in ovarian cancer patients compared to health donors. We also demonstrated that miR-1246 inhibitor treatment in combination with paclitaxel was significantly inhibited tumor burden in SKOV3-ip1 orthotopic ovarian cancer model. Our results suggest that miR-1246 inhibited RB tumor suppressor protein and regulate Cav-1 and platelet-derived growth factor receptor beta precursor signaling in ovarian cancer. In addition Inhibiting miR-1246 led a significant decrease in exosome release. Together, our findings provide strong evidence that oncogenic miR-1246 can be targeted as a potential novel therapeutic approach in the treatment of ovarian cancer. . Note: This abstract was not presented at the meeting. Citation Format: Pinar Kanlikilicer, Recep Bayraktar, Mohammed Rashed, Burcu Aslan, George A. Calin, Anil K. Sood, Gabriel Lopez-Berestein. Exosome-mediated ovarian cancer tumorigenesis mediated by miR1246/Rb/Cav1 axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1988. doi:10.1158/1538-7445.AM2017-1988

Abstract 1035: An angiogenic role of E-cadherin-positive exosomes in ovarian cancer

Abstract Angiogenesis, the induction of vasculature, is a vital step for metastasis. Loss of E-cadherin is a well-established marker for tumor metastasis. In ovarian cancer, a highly metastatic tumor that is rapidly lethal, we and others have previously shown the deregulated pattern of E-cadherin and its close association with tumor progression. Although E-cadherin is synthesized as a transmembrane molecule, it can be shed from the cell surface (sE-cad) which accounts for a rapid removal of functional E-cadherin. Here, in addition to ectodomain shedding, we show for the first time that sE-cad can be actively released from ovarian cancer cells in the form of exosomes. These sE-cad-positive exosomes play a critical role in angiogenesis which stimulated the migration, permeability, and tubulogenesis of human umbilical vein endothelial cells in vitro, and promoted functional neovascularization in vivo. In search of the underlying mechanisms by which sE-cad-positive exosomes might regulate angiogenic endothelial cells, which lack E-cadherin, we showed that a novel heterophilic crosstalk between sE-cad and VE-cadherin. Moreover, such angiogenic effect was mediated through activation of the phosphatidylinositol 3-kinase/Akt-beta-catenin signaling cascade. These results uncover a new angiogenic function for sE-cad and a novel paradigm for sE-cad production which may have potential clinical implications (This study was supported by RGC grant HKU781013). Citation Format: Maggie K. S. Tang, Alice Sze Tsai Wong. An angiogenic role of E-cadherin-positive exosomes 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 1035. doi:10.1158/1538-7445.AM2015-1035

Ovarian cancer cell invasiveness is associated with discordant exosomal sequestration of Let-7 miRNA and miR-200

BackgroundThe role of exosomes in the pathogenesis and metastatic spread of cancer remains to be fully elucidated. Recent studies support the hypothesis that the release of exosomes from cells modifies local extracellular conditions to promote cell growth and neovascularisation. In addition, exosomes may modify the phenotype of parent and/or target cell. For example, sequestration of signaling mediators into exosomes may reduce their intracellular bioavailability to the parent cell thereby altering cell phenotype and metastatic potential. The fusion of released exosomes with target cell and delivery may also modify cell function and activity. In this study, to further elucidate the role of exosomes in ovarian cancer, the release of exosomes from two ovarian cancer cell lines of different invasive capacity and their miRNA content of exosomes were compared. The hypothesis to be tested was that ovarian cancer cell invasiveness is associated with altered release of exosomes and discordant exosomal sequestration of miRNA.MethodsHigh (SKOV-3) and low (OVCAR-3) invasive ovarian cancer cell lines were used to characterize their exosome release. SKOV-3 and OVCAR-3 cells were cultured (DMEM, 20% exosome-free FBS) under an atmosphere of 8% O2 for 24 hours. Cell-conditioned media were collected and exosomes were isolated by differential and buoyant density centrifugation and characterised by Western blot (CD63 and CD9). Exosomal microRNA (let-7a-f and miR-200a-c) content was established by real-time PCR.ResultsExosomes were identified with by the presence of typical cup-shaped spherical vesicle and the expression of exosome markers: CD63, CD9. SKOV-3 cells released 2.7-fold more exosomes (1.22 ± 0.11 μg/106 cells) compared to OVCAR-3 (0.44 ± 0.05 μg/106 cells). The let-7 family miRNA transcripts were identified in both ovarian cancer cell lines and their exosomes. The let-7 family transcripts were more abundant in OVCAR-3 cell than SKOV-3 cells. In contrast, let-7 family transcripts were more abundant in exosomes from SKOV-3 than OVCAR-3. miR-200 family transcripts were only identified in OVCAR-3 cells and their exosomes.ConclusionsThe data obtained in this study are consistent with the hypothesis that the releases of exosomes varies significantly between ovarian cancer cell lines and correlates with their invasive potential.