Long non-coding RNA CTSLP8 mediates ovarian cancer progression and chemotherapy resistance by modulating cellular glycolysis and regulating c-Myc expression through PKM2.

PURPOSE: Long non-coding RNAs (lncRNAs) play vital roles in tumor progression and resistance. Ovarian cancer (OC), a common gynecological cancer, is associated with poor prognosis as it can progress to peritoneal metastasis and develop resistance to chemotherapy. This study aimed to examine the role of lncRNAs in the development of chemotherapy resistance in OC. METHODS: The clinical samples were divided into chemotherapy-sensitive and chemotherapy-resistant groups based on the chemotherapy response at follow-up. The glycolysis levels in the two groups were analyzed using positron emission tomography/computed tomography (PET/CT) scanning and immunohistochemistry. GEO dataset analysis revealed the expression of CTSLP8 in chemotherapy-resistant patients with OC. Two pairs of normal and diamminodichloroplatinum (DDP)-resistant cells were transfected with CTSLP8 overexpression and knockdown constructs to examine the functions of CTSLP8 in the OC cells and elucidate the underlying mechanisms. The in vivo effect of CTSLP8 overexpression and knockdown on the chemotherapy response of tumors was examined using a mouse subcutaneous tumor model. The tissue chips were subjected to fluorescence in situ hybridization and immunohistochemical (IHC) staining to examine the correlation among CTSLP8 expression, DDP resistance, and prognosis in OC. RESULTS: The dataset analysis demonstrated that CTSLP8 was upregulated in chemotherapy-resistant tumor tissues. CTSLP8 promoted the proliferation and development of DDP resistance in the OC cells. Moreover, CTSLP8 promoted c-Myc expression by facilitating the binding of PKM2 to the promoter region of c-Myc, thereby upregulating glycolysis. The analysis of tissue chips revealed that the upregulation of CTSLP8 was associated with the development of DDP resistance and poor prognosis in patients with OC. CONCLUSIONS: These findings indicate that CTSLP8 forms a complex with PKM2 to regulate c-Myc, and this action results in the upregulation of cellular glycolysis, consequently promoting OC progression and development of chemotherapy resistance. HEADLIGHTS: 1. CTSLP8 was upregulated in the chemotherapy-resistant tumor tissues. 2. CTSLP8 promoted the proliferation and cisplatin resistance in the OC cells. 3. CTSLP8 promoted glycolysis by facilitating the binding of PKM2 to the promoter region of c-Myc. 4. Inhibition of CTSLP8 or the combination of c-Myc inhibitors with cisplatin were potential therapeutic strategies for chemotherapy-resistant of OC.

Identification of immune microenvironment subtypes that predicted the prognosis of patients with ovarian cancer.

Ovarian cancer (OC) is associated with high mortality rate. However, the correlation between immune microenvironment and prognosis of OC remains unclear. This study aimed to explore prognostic significance of OC tumour microenvironment. The OC data set was selected from the cancer genome atlas (TCGA), and 307 samples were collected. Hierarchical clustering was performed according to the expression of 756 genes. The immune and matrix scores of all immune subtypes were determined, and Kruskal-Wallis test was used to analyse the differences in the immune and matrix scores between OC samples with different immune subtypes. The model for predicting prognosis was constructed based on the expression of immune-related genes. TIDE platform was applied to predict the effect of immunotherapy on patients with OC of different immune subtypes. The 307 OC samples were classified into three immune subtypes A-C. Patients in subtype B had poorer prognosis and lower survival rate. The infiltration of helper T cells and macrophages in microenvironment indicated significant differences between immune subtypes. Enrichment analyses of immune cell molecular pathways showed that JAK-STAT3 pathway changed significantly in subtype B. Furthermore, predictive response to immunotherapy in subtype B was significantly higher than that in subtype A and C. Immune subtyping can be used as an independent predictor of the prognosis of OC patients, which may be related to the infiltration patterns of immune cells in tumour microenvironment. In addition, patients in immune subtype B have superior response to immunotherapy, suggesting that patients in subtype B are suitable for immunotherapy.

NOL4L, a novel nuclear protein, promotes cell proliferation and metastasis by enhancing the PI3K/AKT pathway in ovarian cancer.

Nucleolar protein 4-like (NOL4L) was first identified in acute myeloid leukaemia. Then, it was verified to be involved in cell progression in neuroblastoma. However, the functional role of NOL4L in tumor proliferation and metastasis and the underlying molecular mechanism(s) are not fully understood. Immunohistochemistry (IHC) assays were performed in patient tissues to reveal NOL4L expression profiles. Then, we knocked down NOL4L in two ovarian cancer cell lines (Skov3-ip1 and Hey), and cell-based in-vitro and in-vivo assays were subsequently conducted to gain insight into the underlying mechanism of NOL4L in ovarian cancer. We confirmed that the expression of NOL4L was higher in tumor tissues, especially in peritoneal metastatic tissues. Furthermore, we observed that NOL4L was related to prognosis in ovarian cancer patients. Next, we conducted CCK-8 assays, colony formation assays, migration and invasion experiments and wound healing assays and verified that NOL4L could promote proliferation and metastasis in ovarian cancer cells. In addition, NOL4L promoted tumor progression and metastasis in a nude mouse model. Mechanistically, we demonstrated that NOL4L influenced gene expression in the PI3K/AKT pathway. Overall, our study provides genetic and biochemical evidence that NOL4L is critical for tumor progression and metastasis in ovarian cancer cells. Thus, it could serve as a target for antimetastatic therapy in ovarian cancer.

Ovarian cancer: epigenetics, drug resistance, and progression.

Ovarian cancer (OC) is one of the most common malignant tumors in women. OC is associated with the activation of oncogenes, the inactivation of tumor suppressor genes, and the activation of abnormal cell signaling pathways. Moreover, epigenetic processes have been found to play an important role in OC tumorigenesis. Epigenetic processes do not change DNA sequences but regulate gene expression through DNA methylation, histone modification, and non-coding RNA. This review comprehensively considers the importance of epigenetics in OC, with a focus on microRNA and long non-coding RNA. These types of RNA are promising molecular markers and therapeutic targets that may support precision medicine in OC. DNA methylation inhibitors and histone deacetylase inhibitors may be useful for such targeting, with a possible novel approach combining these two therapies. Currently, the clinical application of such epigenetic approaches is limited by multiple obstacles, including the heterogeneity of OC, insufficient sample sizes in reported studies, and non-optimized methods for detecting potential tumor markers. Nonetheless, the application of epigenetic approaches to OC patient diagnosis, treatment, and prognosis is a promising area for future clinical investigation.

MUC16 impacts tumor proliferation and migration through cytoplasmic translocation of P120-catenin in epithelial ovarian cancer cells: an original research.

BACKGROUND: Epithelial ovarian cancer (EOC) remains one of the most lethal gynecologic cancers, and its pathogenetic mechanism remains unclear. Here we show that MUC16 promotes the translocation of p120-catenin (p120ctn) to the cytoplasm and consequently activates ras homolog (Rho) GTPases RhoA/Cdc42 activation to modulate the proliferation and migration abilities of EOC cells. METHODS: We collect 94 ovarian cancer (OC) patients' tissue samples to constitute tissue microarray (TMA) and analyze the MUC16 and p120ctn expression levels. Lentivirus transfection is used to overexpress cytoplasmic tail domain (CTD) of MUC16 and CRISPR/Cas9 genome-editing system is firstly used to knock out MUC16 in EOC cells. The proliferation or migration ability of cells is analyzed by MTS or migration assay. RESULTS: We find that MUC16 and p120ctn are aberrantly overexpressed in 94 clinical OC samples compared with benign ovarian tumors (BOT). MUC16 is a critical inducer of the proliferation and migration of EOC cells and the CTD of MUC16 plays an important role during this process. In addition, we reveal the relationship between MUC16 and p120ctn, which has not previously been studied. We show that MUC16 promotes the translocation of p120ctn to the cytoplasm and consequently activates Rho GTPases to modulate the proliferation and migration abilities of EOC cells. The cell proliferation and migration abilities induced by MUC16 are mediated by p120ctn through RhoA/Cdc42 activation. CONCLUSIONS: The highly expressed MUC16 promotes the translocation of p120ctn to the cytoplasm, where it activates RhoA/Cdc42 to modulate the proliferation and migration abilities of EOC cells. These findings may provide new targets for the treatment of EOC.

Performance of a pervaporation system for the separation of an ethanol-water mixture using fractional condensation.

Polydimethylsiloxane (PDMS)/polyvinylidene fluoride (PVDF) composite membranes were fabricated and subsequently applied in ethanol recovery from an ethanol-water mixture by pervaporation (PV) using fractional condensation. The effects of feed temperature and feed flow velocity on the pervaporative properties of PDMS/PVDF composite membranes were investigated. Scanning electron microscopy (SEM) results showed that PDMS was coated uniformly on the surface of porous PVDF substrate, and the PDMS separation layer was dense with a thickness of 1.7 µm. Additionally, it was found that with increasing feed temperature, the total flux of the composite membrane increased, whereas the separation factor decreased. As the feed flow velocity increased, the total flux and separation factor increased. Besides, the permeate vapor was condensed by a two-stage fractional condenser maintained at different temperatures. The effects of the condensation conditions on fractions of ethanol-water vapor were studied to concentrate ethanol in product. The fractional condensers proved to be an effective way to enhance the separation efficiency. Under the optimum fractional condensation conditions, the second condenser showed a flux of 1,329 g/m2 h and the separation factor was increased to 17.2. Furthermore, the long-term operation stability was verified, indicating that the PV system incorporating fractional condensation was a promising approach to separate ethanol from the ethanol-water mixture.

The emerging roles and therapeutic potential of exosomes in epithelial ovarian cancer.

Ovarian cancer (OC) is one of the three types of malignant tumors in the female reproductive system, and epithelial ovarian cancer (EOC) is its most typical form. Due to the asymptomatic nature of the early stages and resistance to chemotherapy, EOC has both a poor prognosis and a high fatality rate. Current treatments for OC are very limited, and the 5-years survival rate is approximately 30%. Exosomes, which are microvesicles ranging from approximately 30-100 nm in size that are secreted by living cells, can be produced from different cell types and detected in various body fluids. Cancer cells can secrete more exosomes than healthy cells, and more importantly, the content of cancer cell-derived exosomes is distinct. The exosomes shedding from tumor cells are considered to be involved in tumor progression and metastasis. As such, exosomes are expected to be potential tools for tumor diagnosis and treatment. In this review, we briefly present the emerging roles of exosomes in OC and summarize related articles about their roles as diagnostic or prognostic biomarkers and in the treatment and drug resistance of OC.

Single-cell analyses implicate ascites in remodeling the ecosystems of primary and metastatic tumors in ovarian cancer.

Ovarian cancer (OC) is an aggressive gynecological tumor usually diagnosed with widespread metastases and ascites. Here, we depicted a single-cell landscape of the OC ecosystem with five tumor-relevant sites, including omentum metastasis and malignant ascites. Our data reveal the potential roles of ascites-enriched memory T cells as a pool for tumor-infiltrating exhausted CD8+ T cells and T helper 1-like cells. Moreover, tumor-enriched macrophages exhibited a preference for monocyte-derived ontogeny, whereas macrophages in ascites were more of embryonic origin. Furthermore, we characterized MAIT and dendritic cells in malignant ascites, as well as two endothelial subsets in primary tumors as predictive biomarkers for platinum-based chemotherapy response. Taken together, our study provides a global view of the female malignant ascites ecosystem and offers valuable insights for its connection with tumor tissues and paves the way for potential markers of efficacy evaluation and therapy resistance in OC.

Stanniocalcin 1 promotes metastasis, lipid metabolism and cisplatin chemoresistance via the FOXC2/ITGB6 signaling axis in ovarian cancer.

BACKGROUND: Stanniocalcin 1 (STC1) plays an integral role in ovarian cancer (OC). However, the functional role of STC1 in metastasis, lipid metabolism and cisplatin (DDP) chemoresistance in OC is not fully understood. METHODS: Single-cell sequencing and IHC analysis were performed to reveal STC1 expression profiles in patient tissues. Metastasis, lipid metabolism and DDP chemoresistance were subsequently assessed. Cell-based in vitro and in vivo assays were subsequently conducted to gain insight into the underlying mechanism of STC1 in OC. RESULTS: Single-cell sequencing assays and IHC analysis verified that STC1 expression was significantly enhanced in OC tissues compared with para-carcinoma tissues, and it was further up-regulated in peritoneal metastasis tissues compared with OC tissues. In vitro and in vivo experiments demonstrated that STC1 promoted metastasis, lipid metabolism and DDP chemoresistance in OC. Simultaneously, STC1 promoted lipid metabolism by up-regulating lipid-related genes such as UCP1, TOM20 and perilipin1. Mechanistically, STC1 directly bound to integrin ß6 (ITGB6) to activate the PI3K signaling pathway. Moreover, STC1 was directly regulated by Forkhead box C2 (FOXC2) in OC. Notably, targeting STC1 and the FOXC2/ITGB6 signaling axis was related to DDP chemoresistance in vitro. CONCLUSIONS: Overall, these findings revealed that STC1 promoted metastasis, lipid metabolism and DDP chemoresistance via the FOXC2/ITGB6 signaling axis in OC. Thus, STC1 may be used as a prognostic indicator in patients with metastatic OC. Meanwhile, STC1 could be a therapeutic target in OC patients, especially those who have developed chemoresistance to DDP.

The lnc-CTSLP8 upregulates CTSL1 as a competitive endogenous RNA and promotes ovarian cancer metastasis.

BACKGROUND: Ovarian cancer is highly lethal and has a poor prognosis due to metastasis. Long non-coding RNAs (lncRNAs) are key regulators of tumor development, but their role in ovarian cancer metastasis remains unclear. METHODS: The expression of lnc-CTSLP8 in ovarian cancer was analyzed in public databases (TCGA and GEO) and validated via qRT-PCR. Lnc-CTSLP8 overexpression and knockout cell lines were constructed using a lentiviral vector and the CRISP/Cas9 system. Cell proliferation, colony formation, migration, and invasion were analyzed. An ovarian orthotopic tumor mouse model was used for the in vivo study. Changes in autophagosomes, autolysosomes, and mitochondria in ovarian cancer cells were observed via transmission electron microscopy. EMT markers were detected by immunoblotting and immunofluorescence assays. RNA immunoprecipitation, RNA pull-down, and dual luciferase reporter assays were performed to confirm the interaction between lnc-CTSLP8 and miR-199a-5p. RESULTS: A novel pseudogene, lnc-CTSLP8, was identified in ovarian cancer, with significantly elevated expression in metastatic tumor tissues compared to primary ovarian tumors. When overexpressed, lnc-CTSLP8 promoted ovarian cancer in vitro and in vivo by acting as a sponge for miR-199a-5p. Autophagy and EMT in ovarian cancer were also enhanced by lnc-CTSLP8. Mechanistically, lnc-CTSLP8 upregulated CTSL1 as a competitive endogenous RNA and exhibited oncogenic effects. Moreover, CTSL1 inhibitor treatment and miR-199a-5p overexpression abrogated the effects of lnc-CTSLP8 overexpression. CONCLUSIONS: lnc-CTSLP8 acts as a ceRNA in ovarian cancer and represents a potential therapeutic target for metastatic ovarian cancer.

Exosomes released from M2 macrophages transfer miR-221-3p contributed to EOC progression through targeting CDKN1B.

In contrast to other solid tumors within the abdominal cavity, epithelial ovarian cancers (EOCs) tend to undergo peritoneal metastasis. Thus, the peritoneal immune microenvironment is crucial for EOC progression. Previous reports indicate that the main immune cells within the peritoneum are M2 macrophages, specifically tumor-associated macrophages (TAMs). The communication between TAMs and tumor cells plays an important role in EOC development, and exosomes, acting as micro-message carriers, occupy an essential position in this process. Microarray analyses of exosomes revealed that miR-221-3p was enriched in M2 exosomes. Furthermore, miR-221-3p suppressed cyclin-dependent kinase inhibitor 1B (CDKN1B) directly. Thus, miR-221-3p contributed to the proliferation and G1/S transition of EOC cells. Additionally, low levels of CDKN1B were associated with EOC progression and poor prognosis. These observations suggest that TAMs-derived exosomal miR-221-3p acts as a regulator of EOC progression by targeting CDKN1B. The results of this study confirm that certain exosomal microRNAs may provide novel diagnostic biomarkers and therapeutic targets for EOC.

Extracellular vesicle-based liquid biopsy holds great promise for the management of ovarian cancer.

Ovarian cancer is a highly lethal gynecological disease because most patients are diagnosed in advanced stages due to a lack of appropriate markers or methods for early detection. Extracellular vesicles (EVs) are small biological vesicles released by all types of cells and are widely distributed in biofluids. These vesicles and their bioactive contents are involved in various aspects of tumorigenesis and development, and some of them could be detected in biofluids from liquid biopsy and used as markers for cancer management. Liquid biopsy is a recently developed method for disease diagnosis and real-time monitoring by detecting biomolecules in biofluids such as plasma. The operation is minimally invasive and relatively convenient, especially for patients with cancer. In this review, we describe the use of EV-based liquid biopsy in ovarian cancer and summarize recent advances in technologies for EV isolation and detection, as well as biomarkers identified from ovarian cancer-derived EVs, with a focus on their potential roles in diagnosis and progression monitoring. Although the advantages of liquid biopsy make this approach promising, some technological challenges remain, and qualified biomarkers for clinical use are still being explored.

Circular RNAs and their emerging roles as diagnostic and prognostic biomarkers in ovarian cancer.

Ovarian cancer (OC), one of the gynecologic malignancies with high invasive and metastatic potential, has a low survival rate in females. Although cytoreductive surgery combined with chemotherapy is the principal treatment for OC, the prognosis remains poor, and the recurrence rate of OC remains high. It is urgent to explore novel biomarkers for the diagnosis and prognosis of OC, as well as therapeutic targets. Circular RNAs (circRNAs) are a class of highly conserved, stable and abundant noncoding RNAs (ncRNAs). Recent studies have shown that circRNAs participate in OC progression by regulating various processes, including cell proliferation, migration, invasion and apoptosis. In addition, circRNAs are potential biomarkers for OC diagnosis and prognosis. This review provides an overview of recent findings on circRNAs in OC, including their functions and molecular mechanisms, and discusses their potential roles as diagnostic and prognostic biomarkers, as well as therapeutic targets for OC.

The exosomal integrin α5ß1/AEP complex derived from epithelial ovarian cancer cells promotes peritoneal metastasis through regulating mesothelial cell proliferation and migration.

PURPOSE: Epithelial ovarian cancer (EOC) is one of the most malignant cancers in the gynecologic system. Many patients are diagnosed at an advanced stage with disseminated intra-peritoneal metastases. EOC spreads via both direct extension and trans-coelomic spread. However, the interplay between human peritoneal mesothelial cells (HPMCs) and EOC cells is still ambiguous. We hypothesize that integrins (ITG) in HPMCs may play important roles in EOC metastasis. METHODS: The expression of different integrin subtypes from HPMCs was assessed using Western blotting. The expression of integrin α5ß1 (ITGA5B1) and its co-localization with asparaginyl endopeptidase (AEP) in HPMCs derived from EOC patients (EOC-HPMCs) were assessed using immunofluorescence. The role and mechanism of the exosomal ITGA5B1/AEP complex in HPMCs was assessed using both in vitro and in vivo assays. A retrospective study involving 234 cases was carried out to assess ITGA5B1 and AEP levels in circulating sera and ascites of EOC patients, as well as associations between ITGA5B1/AEP expression and overall survival. RESULTS: We found that ITGA5B1was highly expressed and co-localized with AEP in EOC cells, and that the exosomal ITGA5B1/AEP complex secreted by EOC cells played an important role in the proliferation and migration of HPMCs. High levels of exosomal ITGA5B1/AEP were also found in circulating sera and ascites of EOC patients, and the expression of ITGA5B1/AEP in EOC tissues was found to be negatively associated with overall survival. CONCLUSIONS: Our data indicate that EOCs may regulate the function of HPMCs through exosomal ITGA5B1/AEP, which may be crucial for peritoneal metastasis.

An Update on Circumventing Multidrug Resistance in Cancer by Targeting P-Glycoprotein.

BACKGROUND: The ultimate emergence of multidrug resistance remains a severe limitation of chemotherapy treatment for patients with cancer. The best-characterized cause of drug resistance involves the overexpression of P-glycoprotein (Pgp), which decreases the intracellular accumulation of chemotherapeutic agents in drug-resistant cancer cells. Thus, Pgp has become an attractive potential target for treating chemotherapy-resistant cancer, but the outcomes of using chemotherapy in combination with Pgp inhibitors in clinical trials to date have been disappointing. OBJECTIVE: We herein examine the relationship between Pgp and drug resistance and update the strategies for overcoming drug resistance by targeting Pgp, with a special focus on the recent progress in the area of preventing the development of drug resistance by targeting Pgp both in vitro and in vivo. Given the essential roles of drug-resistant cancer models in these investigations, commonly used approaches for establishing drug-resistant models in the laboratory are also addressed. CONCLUSION: Considering the roles of Pgp in normal physiological conditions and its appreciated roles in detoxification, the currently available Pgp inhibitors undoubtedly cannot be used to reverse drug resistance in the clinic. Although agents that target Pgp to prevent and/or reverse drug resistance are not beneficial at the doses used in the laboratory when administered to patients with cancer who are enrolled in clinical trials, compounds targeting Pgp are widely acknowledged to be promising for circumventing drug resistance.

Exosomes derived from hypoxic epithelial ovarian cancer cells deliver microRNAs to macrophages and elicit a tumor-promoted phenotype.

Recently, cancer has been considered to be a complex system that includes the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are the most common immune-related stromal cells in the TME, and communication between cancer cells and TAMs is crucial for the progression of epithelial ovarian cancer (EOC). In this study, we revealed that exosomes derived from EOC cells remodel macrophages to a tumor-promoted phenotype, namely TAMs. In addition, hypoxic microenvironments have been postulated to facilitate this process in the TME, and hypoxia-inducible factors (HIFs) play an important role in this process. We found that TAMs educated by hypoxic exosomes derived from EOC cells promote tumor proliferation and migration in a feedback loop. Based on microarray analysis of normoxic and hypoxic exosomes, we discovered that a panel of miRNAs was enriched in hypoxic exosomes. And these three highly expressed miRNAs were induced by hypoxia via HIFs. In this study, we revealed that under hypoxic conditions, EOC cell-derived exosomes deliver miRNAs to induce M2 macrophage polarization, which promotes EOC cell proliferation and migration. This study suggests that these exosomes and associated miRNAs might serve as targets for novel treatments or diagnostic biomarkers for EOC.

Upregulation of IGF1 by tumor-associated macrophages promotes the proliferation and migration of epithelial ovarian cancer cells.

Ovarian cancer (OC), of which epithelial ovarian cancer (EOC) is the most common, is the deadliest gynecological tumor because of the difficulties in detection at early stages, and metastasis and chemoresistance at advanced stages. Tumor-associated macrophages (TAMs) differentiate through alternative pathways and play important roles in tumor growth and metastasis. However, the underlying mechanism remains unclear. Here, we established a mouse TAM model using bone marrow monocytes and conditioned medium (CM) of TAMs to culture ID8 mouse EOC cells. The results showed that TAM CM accelerated the proliferation and migration of ID8 cells. In a previous study, gene chip analysis showed that human TAMs expressed significantly higher levels of insulin-like growth factor­1 (IGF1) than undifferentiated M0 myeloid cells. In the present study, we observed that the IGF1 level was higher in human EOC specimens than that in benign ovarian tumor specimens, and further analysis showed that a higher level of IGF1 was related to more advanced clinical stage and liver metastasis. Therefore, we hypothesized that TAMs may accelerate the proliferation and migration of EOC cells by upregulating IGF1. As expected, increased IGF1 expression at both the mRNA and protein levels was observed in ID8 cells cultured with TAM CM, whereas blockade of the IGF1 pathway in ID8 cells with an IGF1 neutralizing antibody effectively reversed the promotion of proliferation and migration. Finally, we inhibited the phosphorylation of insulin-like growth factor­1 receptor (IGF1R) and its downstream molecules Akt and Erk with the IGF1R inhibitor linsitinib, and observed that the treatment effectively suppressed the proliferation and migration of ID8 cells exposed to TAM CM. Thus, we demonstrated that TAMs may promote the growth and metastasis of EOC via the activation of the IGF1 pathway; thus, targeting the IGF1 pathway may be promising for EOC therapy.

Exosomes Released from Tumor-Associated Macrophages Transfer miRNAs That Induce a Treg/Th17 Cell Imbalance in Epithelial Ovarian Cancer.

The immune microenvironment is crucial for epithelial ovarian cancer (EOC) progression and consists of tumor-associated macrophages (TAM) and T lymphocytes, such as regulatory T cells (Treg) and T helper 17 (Th17) cells. In this study, the Treg/Th17 ratio was significantly higher in EOC in situ and in metastatic peritoneal tissues than in benign ovarian tumors and benign peritoneum. The Treg/Th17 ratio was associated with histologic grade and was an independent prognostic factor for overall survival of EOC patients. On the basis of microarray analysis of exosomes derived from TAMs, we identified miRNAs enriched in the exosomes, including miR-29a-3p and miR-21-5p. When the two miRNA mimics were transfected into CD4+ T cells, they directly suppressed STAT3 and regulated Treg/Th17 cells, inducing an imbalance, and they had a synergistic effect on STAT3 inhibition. Taken together, these results indicate that exosomes mediate the interaction between TAMs and T cells, generating an immune-suppressive microenvironment that facilitates EOC progression and metastasis. These findings suggest that targeting these exosomes or their associated miRNAs might pave the way for the development of novel treatments for EOC.