Extracellular Vesicle Transmission of Chemoresistance to Ovarian Cancer Cells Is Associated with Hypoxia-Induced Expression of Glycolytic Pathway Proteins, and Prediction of Epithelial Ovarian Cancer Disease Recurrence

High-risk patient profiles for ovarian cancer: A new approach using cluster analysis of tumor markers

OBJECTIVE

Ovarian cancer remains a leading cause of cancer-related deaths in women. Early detection improves prognosis, but current diagnostic tools still need improvement. We aimed to identify high-risk patient profiles for ovarian cancer using cluster analysis of age and tumor marker data.

MATERIAL AND METHODS

A secondary dataset analysis was conducted using unsupervised learning techniques. Data were from a University Hospital, originally collected between July 2011 and July 2018 in Taiwan. In total, 349 women diagnosed with ovarian masses, including both benign and malignant tumors, were included in this analysis. The median age was 45 years, and 49 % were diagnosed with ovarian cancer in pathology. We used a hierarchical clustering algorithm to find groups of patients with similar features.

RESULTS

Two clusters were identified (N = 204 and 145), with a high-risk cluster (66.2 % malignancy) characterized by significantly older age, higher CA125, HE4, CEA, and AFP levels, and a lower CA19-9 level than the low-risk cluster (24.8 % malignancy). The assessment of clustering stability and internal validity yielded a figure of merit score of 0.970 and a silhouette coefficient of 0.524. A classification model using age, CA125, HE4, and CA19-9 demonstrated high accuracy (89.4 %), sensitivity (94.5 %), specificity (83.7 %), and a large area under the curve (89.1 %) for the risk stratification.

CONCLUSION

Integrating tumor markers with patient demographics improved the differentiation between benign and malignant ovarian masses. This approach can help clinicians prioritize high-risk patients for further diagnostic evaluation and reduce unnecessary invasive procedures for low-risk patients.

REV7: a small but mighty regulator of genome maintenance and cancer development

REV7, also known as MAD2B, MAD2L2, and FANCV, is a HORMA-domain family protein crucial to multiple genome stability pathways. REV7's canonical role is as a member of polymerase ζ, a specialized translesion synthesis polymerase essential for DNA damage tolerance. REV7 also ensures accurate cell cycle progression and prevents premature mitotic progression by sequestering an anaphase-promoting complex/cyclosome activator. Additionally, REV7 supports genome integrity by directing double-strand break repair pathway choice as part of the recently characterized mammalian shieldin complex. Given that genome instability is a hallmark of cancer, it is unsurprising that REV7, with its numerous genome maintenance roles, is implicated in multiple malignancies, including ovarian cancer, glioma, breast cancer, malignant melanoma, and small-cell lung cancer. Moreover, high REV7 expression is associated with poor prognoses and treatment resistance in these and other cancers. Promisingly, early studies indicate that REV7 suppression enhances sensitivity to chemotherapeutics, including cisplatin. This review aims to provide a comprehensive overview of REV7's myriad roles in genome maintenance and other functions as well as offer an updated summary of its connections to cancer and treatment resistance.

Extracellular vesicles in cancers: mechanisms, biomarkers, and therapeutic strategies

Extracellular vesicles (EVs) composed of various biologically active constituents, such as proteins, nucleic acids, lipids, and metabolites, have emerged as a noteworthy mode of intercellular communication. There are several categories of EVs, including exosomes, microvesicles, and apoptotic bodies, which largely differ in their mechanisms of formation and secretion. The amount of evidence indicated that changes in the EV quantity and composition play a role in multiple aspects of cancer development, such as the transfer of oncogenic signals, angiogenesis, metabolism remodeling, and immunosuppressive effects. As EV isolation technology and characteristics recognition improve, EVs are becoming more commonly used in the early diagnosis and evaluation of treatment effectiveness for cancers. Actually, EVs have sparked clinical interest in their potential use as delivery vehicles or vaccines for innovative antitumor techniques. This review will focus on the function of biological molecules contained in EVs linked to cancer progression and their participation in the intricate interrelationship within the tumor microenvironment. Furthermore, the potential efficacy of an EV-based liquid biopsy and delivery cargo for treatment will be explored. Finally, we explicitly delineate the limitations of EV-based anticancer therapies and provide an overview of the clinical trials aimed at improving EV development.

The possible role of hypoxia-induced exosomes on the fibroblast metabolism in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) has a high incidence and prevalence among patients over 65 years old. While its exact etiology remains unknown, several risk factors have recently been identified. Hypoxia is associated with IPF due to the abnormal architecture of lung parenchyma and the accumulation of extracellular matrix produced by activated fibroblasts. Exosomes play a crucial role in intercellular communication during both physiological and pathological processes, including hypoxic diseases like IPF. Recent findings suggest that a hypoxic microenvironment influences the content of exosomes in various diseases, thereby altering cellular metabolism. Although the role of exosomes in IPF is an emerging area of research, the significance of hypoxic exosomes as inducers of metabolic reprogramming in fibroblasts is still underexplored. In this study, we analyze and discuss the relationship between hypoxia, exosomal cargo, and the metabolic reprogramming of fibroblasts in the progression of IPF.

Integrated analysis of single-cell and bulk transcriptome reveals hypoxia-induced immunosuppressive microenvironment to predict immunotherapy response in high-grade serous ovarian cancer

Background

Hypoxia is significantly associated with cancer progression and treatment outcomes. Nevertheless, the precise molecular mechanisms underlying the hypoxia-induced immunosuppressive microenvironment in high-grade serous ovarian cancer (HGSOC) are still not fully understood.

Methods

By analyzing five independent transcriptomic datasets, we investigated the effect of hypoxia on prognosis and tumor microenvironment (TME) in HGSOC. The hypoxia levels and the intercellular communication signaling pathways were studied by using single-cell analysis. Furthermore, the Hypoxia-TME classifier was developed and then validated in the multiple HGSOC datasets. In addition, we also investigated the prognostic significance, genetic variations, signaling pathways, and the potential for immunotherapy benefits in different Hypoxia-TME subgroups.

Results

Hypoxia was identified as a crucial risk factor in HGSOC, and strongly correlated with an immunosuppressive microenvironment characterized by alterations in the composition and distribution of immune cells. Single-cell analysis elucidated the heterogeneity inherent within the TME in HGSOC, and demonstrated an association between the hypoxic TME and fibroblasts as well as macrophages. CellChat analysis identified SPP1-CD44 and CXCL12-CXCR4 as the principal signaling axes through which macrophages and fibroblasts interact with T cells, respectively. Moreover, a personalized Hypoxia-TME classifier was constructed and validated through the integration of the hypoxia (18 genes) and TME (7 immune cells) scores. It was observed that patients in the Hypoxialow/TMEhigh subgroup displayed a significantly better prognosis than other subgroups. Different subgroups exhibited unique genomic alterations and variations in signaling pathway differences, including TGF-β and Wnt/β-catenin pathways, which are closely associated with various biological functions. Finally, our results indicated that patients in the Hypoxialow/TMEhigh subgroup exhibit a better response to immunotherapy, suggesting the potential utility of the Hypoxia-TME classifier as a new biomarker in HGSOC.

Conclusion

Our study revealed hypoxia-induced immunosuppressive microenvironment, and developed Hypoxia-TME classifier to distinguish the prognosis, immune characteristics, and potential benefits of immunotherapy in HGSOC.

PpIX-enabled fluorescence-based detection and photodynamic priming of platinum-resistant ovarian cancer cells under fluid shear stress

Over 75% percent of ovarian cancer patients are diagnosed with advanced-stage disease characterized by unresectable intraperitoneal dissemination and the presence of ascites, or excessive fluid build-up within the abdomen. Conventional treatments include cytoreductive surgery followed by multi-line platinum and taxane chemotherapy regimens. Despite an initial response to treatment, over 75% of patients with advanced-stage ovarian cancer will relapse and succumb to platinum-resistant disease. Recent evidence suggests that fluid shear stress (FSS), which results from the movement of fluid such as ascites, induces epithelial-to-mesenchymal transition and confers resistance to carboplatin in ovarian cancer cells. This study demonstrates, for the first time, that FSS-induced platinum resistance correlates with increased cellular protoporphyrin IX (PpIX), the penultimate downstream product of heme biosynthesis, the production of which can be enhanced using the clinically approved pro-drug aminolevulinic acid (ALA). These data suggest that, with further investigation, PpIX could serve as a fluorescence-based biomarker of FSS-induced platinum resistance. Additionally, this study investigates the efficacy of PpIX-enabled photodynamic therapy (PDT) and the secretion of extracellular vesicles under static and FSS conditions in Caov-3 and NIH:OVCAR-3 cells, two representative cell lines for high-grade serous ovarian carcinoma (HGSOC), the most lethal form of the disease. FSS induces resistance to ALA-PpIX-mediated PDT, along with a significant increase in the number of EVs. Finally, the ability of PpIX-mediated photodynamic priming (PDP) to enhance carboplatin efficacy under FSS conditions is quantified. These preliminary findings in monolayer cultures necessitate additional studies to determine the feasibility of PpIX as a fluorescence-based indicator, and mediator of PDP, to target chemoresistance in the context of FSS.

The signature of extracellular vesicles in hypoxic breast cancer and their therapeutic engineering

Breast cancer (BC) currently ranks second in the global cancer incidence rate. Hypoxia is a common phenomenon in BC. Under hypoxic conditions, cells in the tumor microenvironment (TME) secrete numerous extracellular vesicles (EVs) to achieve intercellular communication and alter the metabolism of primary and metastatic tumors that shape the TME. In addition, emerging studies have indicated that hypoxia can promote resistance to tumor treatment. Engineered EVs are expected to become carriers for cancer treatment due to their high biocompatibility, low immunogenicity, high drug delivery efficiency, and ease of modification. In this review, we summarize the mechanisms of EVs in the primary TME and distant metastasis of BC under hypoxic conditions. Additionally, we highlight the potential applications of engineered EVs in mitigating the malignant phenotypes of BC cells under hypoxia.

Enhancing precision targeting of ovarian cancer tumor cells in vivo through extracellular vesicle engineering

Extracellular vesicles (EVs) function as natural mediators of intercellular communication, secreted by cells to facilitate cell-cell signaling. Due to their low toxicity, immunogenicity, biodegradability, and potential to encapsulate therapeutic drugs, EVs hold significant therapeutic promise. Nevertheless, their limited targeting ability often diminishes their therapeutic impact. Therefore, enhancing EVs by incorporating targeting units onto their membranes could bolster their targeting capabilities, enabling them to accumulate in specific cells and tissues. In this study, we engineered EVs to fuse ephrin-B2 with the EV membrane protein LAMP2b. This modification aimed to direct the engineered EVs toward the ephrin-B4 receptor expressed on the surface of ovarian cancer cells. The engineered EVs retained their inherent properties, including size, expression of EV membrane proteins, and morphology, upon isolation. In vitro experiments using real-time imaging revealed that EVs engineered with the ephrin-B2 ligand exhibited substantial internalization and uptake by ovarian cancer cells, in stark contrast to native EVs. In vivo, the engineered EVs carrying the ephrin-B2 ligand effectively targeted ovarian cancer cells, surpassing the targeting efficiency of control EVs. This innovative approach establishes a novel targeting system, enhancing the uptake of EVs by ovarian cancer cells. Our findings underscore the potential of using EVs to target cancer cells, thereby enhancing the effectiveness of anti-cancer therapies while minimizing off-target effects and toxicity in normal cells and organs.

Value analysis of preoperative peripheral blood LMR in predicting prognosis of serous papillary ovarian adenocarcinoma

OBJECTIVE

To analyze the predictive effect of preoperative peripheral blood leukocyte related inflammatory indicators on the prognosis of patients with serous papillary ovarian adenocarcinoma.

METHODS

A retrospective analysis was conducted on the case data of 83 patients with ovarian cancer undergoing tumor cell reduction surgery admitted to our hospital from January 2017 to December 2020. Pathological findings confirmed serous papillary ovarian adenocarcinoma. Kaplan-Meier method was used to analyze the relationship between lymphocyte to monocyte ratio (LMR) and the patients survival prognosis. Analyzing factors affecting patient prognosis which using a multivariable Cox risk.

RESULTS

The overall survival (OS) of the patients with serous papillary ovarian adenocarcinoma in high LMR group was higher than that in the low LMR group preoperative. The disease free survival (DFS) of ovarian adenocarcinoma patients in the high LMR group was higher than that in the low LMR group preoperative. That was the low LMR indicating a poor prognosis. Single factor analysis showed that age of onset was correlated with OS and DFS, and the body mass index (BMI) was only correlated with OS. Multivariable analysis showed that the age of onset (HR = 2.571, 95% CI 1.199-5.512, P = 0.015) and BMI (HR = 0.337, 95% CI 0.158-0.718, P = 0.005) were independent risk factors for OS.

CONCLUSIONS

Although the serous papillary ovarian adenocarcinoma patients with preoperative peripheral blood LMR reduction have poor prognosis, the correlation between LMR values and prognosis is not significant. Therefore, it is not recommended to use preoperative peripheral leukocyte related inflammatory indicators as prognostic markers for serous papillary ovarian adenocarcinoma.

Chemo-small extracellular vesicles released in cisplatin-resistance ovarian cancer cells are regulated by the lysosomal function

Chemoresistance is a common problem in ovarian cancer (OvCa) treatment, where resistant cells, in response to chemotherapy, secrete small extracellular vesicles (sEVs), known as chemo-sEVs, that transfer resistance to recipient cells. sEVs are formed as intraluminal vesicles (ILVs) within multivesicular endosomes (MVEs), whose trafficking is regulated by Ras-associated binding (RAB) GTPases that mediate sEVs secretion or lysosomal degradation. A decrease in lysosomal function can promote sEVs secretion, but the relationship between MVEs trafficking pathways and sEVs secretion in OvCa chemoresistance is unclear. Here, we show that A2780cis cisplatin (CCDP) resistant OvCa cells had an increased number of MVEs and ILVs structures, higher levels of Endosomal Sorting Complex Required for Transport (ESCRTs) machinery components, and RAB27A compared to A2780 CDDP-sensitive OvCa cells. CDDP promoted the secretion of chemo-sEVs in A2780cis cells, enriched in DNA damage response proteins. A2780cis cells exhibited poor lysosomal function with reduced levels of RAB7, essential in MVEs-Lysosomal trafficking. The silencing of RAB27A in A2780cis cells prevents the Chemo-EVs secretion, reduces its chemoresistance and restores lysosomal function and levels of RAB7, switching them into an A2780-like cellular phenotype. Enhancing lysosomal function with rapamycin reduced chemo-sEVs secretion. Our results suggest that adjusting the balance between secretory MVEs and lysosomal MVEs trafficking could be a promising strategy for overcoming CDDP chemoresistance in OvCa.

Low-Density Lipoproteins Increase Proliferation, Invasion, and Chemoresistance via an Exosome Autocrine Mechanism in MDA-MB-231 Chemoresistant Cells

Dyslipidemias involving high concentrations of low-density lipoproteins (LDLs) increase the risk of developing triple-negative breast cancer (TNBC), wherein cholesterol metabolism and protein translation initiation mechanisms have been linked with chemoresistance. Doxorubicin (Dox) treatment, a member of the anthracycline family, represents a typical therapeutic strategy; however, chemoresistance remains a significant challenge. Exosomes (Exs) secreted by tumoral cells have been implicated in cell communication pathways and chemoresistance mechanisms; the content of exosomes is an outcome of cellular cholesterol metabolism. We previously induced Dox resistance in TNBC cell models, characterizing a variant denominated as variant B cells. Our results suggest that LDL internalization in parental and chemoresistant variant B cells is associated with increased cell proliferation, migration, invasion, and spheroid growth. We identified the role of eIF4F translation initiation factor and the down-regulation of tumor suppressor gene PDCD4, an inhibitor of eIF4A, in chemoresistant variant B cells. In addition, the exomes secreted by variant B cells were characterized by the protein content, electronic microscopy, and cell internalization assays. Critically, exosomes purified from LDL-treated variant B cell promoted cell proliferation, migration, and an increment in lactate concentration. Our results suggest that an autocrine phenomenon induced by exosomes in chemoresistant cells may induce modifications on signaling mechanisms of the p53/Mdm2 axis and activation of p70 ribosomal protein kinase S6. Moreover, the specific down-regulated profile of chaperones Hsp90 and Hsp70 secretion inside the exosomes of the chemoresistant variant could be associated with this phenomenon. Therefore, autocrine activation mediated by exosomes and the effect of LDL internalization may influence changes in exosome chaperone content and modulate proliferative signaling pathways, increasing the aggressiveness of MDA-MB-231 chemoresistant cells.

Prediction of Chemoresistance-How Preclinical Data Could Help to Modify Therapeutic Strategy in High-Grade Serous Ovarian Cancer

High-grade serous ovarian cancer (HGSOC) is one of the most lethal tumors generally and the most fatal cancer of the female genital tract. The approved standard therapy consists of surgical cytoreduction and platinum/taxane-based chemotherapy, and of targeted therapy in selected patients. The main therapeutic problem is chemoresistance of recurrent and metastatic HGSOC tumors which results in low survival in the group of FIGO III/IV. Therefore, the prediction and monitoring of chemoresistance seems to be of utmost importance for the improvement of HGSOC management. This type of cancer has genetic heterogeneity with several subtypes being characterized by diverse gene signatures and disturbed peculiar epigenetic regulation. HGSOC develops and metastasizes preferentially in the specific intraperitoneal environment composed mainly of fibroblasts, adipocytes, and immune cells. Different HGSOC subtypes could be sensitive to distinct sets of drugs. Moreover, primary, metastatic, and recurrent tumors are characterized by an individual biology, and thus diverse drug responsibility. Without a precise identification of the tumor and its microenvironment, effective treatment seems to be elusive. This paper reviews tumor-derived genomic, mutational, cellular, and epigenetic biomarkers of HGSOC drug resistance, as well as tumor microenvironment-derived biomarkers of chemoresistance, and discusses their possible use in the novel complex approach to ovarian cancer therapy and monitoring.

Extracellular vesicles targeting tumor microenvironment in ovarian cancer

Ovarian cancer (OC) is a prevalent neoplastic condition affecting women. Extracellular vesicles (EVs), nano-sized membrane vesicles, are secreted by various cells in both physiological and pathological states. The profound interplay between EVs and the tumor microenvironment (TME) in ovarian cancer is crucial. In this review, we explores the pivotal role of EVs in facilitating intercellular communication between cancer cells and the TME, emphasizing the potential of EVs as promising diagnostic markers and innovative therapeutic targets for ovarian cancer. The comprehensive analysis outlines the specific mechanisms by which EVs engage in communication with the constituents of the TME, including the modulation of tumor growth through EVs carrying matrix metalloproteinases (MMPs) and EV-mediated inhibition of angiogenesis, among other factors. Additionally, the we discuss the potential clinical applications of EVs that target the TME in ovarian cancer, encompassing the establishment of novel treatment strategies and the identification of novel biomarkers for early detection and prognosis. Finally, this review identifies novel strategies for therapeutic interventions, such as utilizing EVs as carriers for drug delivery and targeting specific EV-mediated signaling pathways. In summary, this manuscript offers valuable insights into the role of EVs in ovarian cancer and highlights the significance of comprehending intercellular communication in the realm of cancer biology.

Hypoxic regulation of extracellular vesicles: Implications for cancer therapy

Extracellular vesicles (EVs) play a pivotal role in intercellular communication and have been implicated in cancer progression. Hypoxia, a pervasive hallmark of cancer, is known to regulate EV biogenesis and function. Hypoxic EVs contain a specific set of proteins, nucleic acids, lipids, and metabolites, capable of reprogramming the biology and fate of recipient cells. Enhancing the intrinsic therapeutic efficacy of EVs can be achieved by strategically modifying their structure and contents. Moreover, the use of EVs as drug delivery vehicles holds great promise for cancer treatment. However, various hurdles must be overcome to enable their clinical application as cancer therapeutics. In this review, we aim to discuss the current knowledge on the hypoxic regulation of EVs. Additionally, we will describe the underlying mechanisms by which EVs contribute to cancer progression in hypoxia and outline the progress and limitations of hypoxia-related EV therapeutics for cancer.

Role of exosomes in transferring chemoresistance through modulation of cancer glycolytic cell metabolism

Chemoresistance constitute a major obstacle in cancer treatment, leading to limited options and decreased patient survival. Recent studies have revealed a novel mechanism of chemoresistance acquisition: the transfer of information via exosomes, small vesicles secreted by various cells. Exosomes play a crucial role in intercellular communication by carrying proteins, nucleic acids, and metabolites, influencing cancer cell behavior and response to treatment. One crucial mechanism of resistance is cancer metabolic reprogramming, which involves alterations in the cellular metabolic pathways to support the survival and proliferation of drug-resistant cancer cells. This metabolic reprogramming often includes increased glycolysis, providing cancer cells with the necessary energy and building blocks to evade the effects of chemotherapy. Notably, exosomes have been found to transport glycolytic enzymes, as identified in proteomic profiling, leading to the reprogramming of metabolic pathways, facilitating altered glucose metabolism and increased lactate production. As a result, they profoundly impact the tumor microenvironment, promoting tumor progression, survival, immune evasion, and drug resistance.Understanding the complexities of such exosome-mediated cell-to-cell communication might open new therapeutic avenues and facilitate biomarker development in managing cancers characterized by aggressive glycolytic features. Moreover, given the intricate nature of metabolic abnormalities combining future exosome-based-targeted therapies with existing treatments like chemotherapy, immunotherapy, and targeted therapies holds promise for achieving synergistic effects to overcome resistance and improve cancer treatment outcomes.

The role of Extracellular Vesicles in glycolytic and lipid metabolic reprogramming of cancer cells: Consequences for drug resistance

In order to adapt to a higher proliferative rate and an increased demand for energy sources, cancer cells rewire their metabolic pathways, a process currently recognized as a hallmark of cancer. Even though the metabolism of glucose is perhaps the most discussed metabolic shift in cancer, lipid metabolic alterations have been recently recognized as relevant players in the growth and proliferation of cancer cells. Importantly, some of these metabolic alterations are reported to induce a drug resistant phenotype in cancer cells. The acquisition of drug resistance traits severely hinders cancer treatment, being currently considered one of the major challenges of the oncological field. Evidence suggests that Extracellular Vesicles (EVs), which play a crucial role in intercellular communication, may act as facilitators of tumour progression, survival and drug resistance by modulating several aspects involved in the metabolism of cancer cells. This review aims to gather and discuss relevant data regarding metabolic reprograming in cancer, particularly involving the glycolytic and lipid alterations, focusing on its influence on drug resistance and highlighting the relevance of EVs as intercellular mediators of this process.

Cell culture-derived extracellular vesicles: Considerations for reporting cell culturing parameters

Cell culture-conditioned medium (CCM) is a valuable source of extracellular vesicles (EVs) for basic scientific, therapeutic and diagnostic applications. Cell culturing parameters affect the biochemical composition, release and possibly the function of CCM-derived EVs (CCM-EV). The CCM-EV task force of the Rigor and Standardization Subcommittee of the International Society for Extracellular Vesicles aims to identify relevant cell culturing parameters, describe their effects based on current knowledge, recommend reporting parameters and identify outstanding questions. While some recommendations are valid for all cell types, cell-specific recommendations may need to be established for non-mammalian sources, such as bacteria, yeast and plant cells. Current progress towards these goals is summarized in this perspective paper, along with a checklist to facilitate transparent reporting of cell culturing parameters to improve the reproducibility of CCM-EV research.

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.

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.

Small extracellular vesicle-mediated metabolic reprogramming: from tumors to pre-metastatic niche formation

Metastasis, the spread of a tumor or cancer from the primary site of the body to a secondary site, is a multi-step process in cancer progression, accounting for various obstacles in cancer treatment and most cancer-related deaths. Metabolic reprogramming refers to adaptive metabolic changes that occur in cancer cells in the tumor microenvironment (TME) to enhance their survival ability and metastatic potential. Stromal cell metabolism also changes to stimulate tumor proliferation and metastasis. Metabolic adaptations of tumor and non-tumor cells exist not only in the TME but also in the pre-metastatic niche (PMN), a remote TME conducive for tumor metastasis. As a novel mediator in cell-to-cell communication, small extracellular vesicles (sEVs), which have a diameter of 30-150 nm, reprogram metabolism in stromal and cancer cells within the TME by transferring bioactive substances including proteins, mRNAs and miRNAs (microRNAs). sEVs can be delivered from the primary TME to PMN, affecting PMN formation in stroma rewriting, angiogenesis, immunological suppression and matrix cell metabolism by mediating metabolic reprogramming. Herein, we review the functions of sEVs in cancer cells and the TME, how sEVs facilitate PMN establishment to trigger metastasis via metabolic reprogramming, and the prospective applications of sEVs in tumor diagnosis and treatment. Video Abstract.

Metabolic reprogramming and interventions in endometrial carcinoma

Cancer cells are usually featured by metabolic adaptations that facilitate their growth, invasion, and metastasis. Thus, reprogramming of intracellular energy metabolism is currently one of the hotspots in the field of cancer research. Whereas aerobic glycolysis (known as the Warburg effect) has long been considered a dominant form of energy metabolism in cancer cells, emerging evidence indicates that other metabolic forms, especially oxidative phosphorylation (OXPHOS), may play a critical role at least in some types of cancer. Of note, women with metabolic syndromes (MetS), including obesity, hyperglycemia, dyslipidemia, and hypertension, have an increased risk of developing endometrial carcinoma (EC), suggesting a close link between metabolism and EC. Interestingly, the metabolic preferences vary among EC cell types, particularly cancer stem cells and chemotherapy-resistant cells. Currently, it is commonly accepted that glycolysis is the main energy provider in EC cells, while OXPHOS is reduced or impaired. Moreover, agents specifically targeting the glycolysis and/or OXPHOS pathways can inhibit tumor cell growth and promote chemosensitization. For example, metformin and weight control not only reduce the incidence of EC but also improve the prognosis of EC patients. In this review, we comprehensively overview the current in-depth understanding of the relationship between metabolism and EC and provide up-to-date insights into the development of novel therapies targeting energy metabolism for auxiliary treatment in combination with chemotherapy for EC, especially those resistant to conventional chemotherapy.

The current trend of exosome in epithelial ovarian cancer studies: A bibliometric review

Background: Epithelial ovarian cancer (EOC) is the most common type of ovarian cancer. About 90% of ovary tumors are epithelial. The current treatment for EOC involves surgical debulking of the tumors followed by a combination of chemotherapy. While most patients achieve complete remission, many EOCs will recur and develop chemoresistance. The cancer cells can adapt to several stress stimuli, becoming resistant. Therefore, new ways to fight resistant cells during the disease are being studied. Recently, exosomes, which reflect cell behavior in normal and pathological conditions such as epithelial ovarian cancer, are of academic interest as new biomarkers for diagnosis and therapy. Consequently, the current study aimed to investigate the research output of exosomes in EOC. Method: A bibliometric method was used for analyzing publications on exosome and epithelial ovarian cancer from the beginning to 15 October 2022 by searching keywords in Scopus, PubMed and Google scholar. Annual scientific publications, authors, citations, journals, co-authorships, and keywords co-occurrence were analyzed and plotted using Microsoft Office Excel and VOS viewer. 39 original journal articles and 3 reviews have been published since 2015 up to 15 October 2022. Results: The findings showed that China is the top country in research output, international collaborations, organization, author, and sponsorship. The top journals were the Journal of Ovarian Research, Oncotarget, and Tumor Biology, all in the United States. The top institution was Shanghai Jiao Tong University in China. The top author was Xipeng Wang. Co-occurrence analysis showed that academics' interest is toward:1) 1) Exosomes as prognostic biomarkers of EOC as well as their role in the proliferation and migration of cells. 2) The role of exosomes in metastasis through different mechanisms; 3) The role of exosomes in epithelial-mesenchymal transition of ovarian cancer cells; 4) The diagnostic role of EVs in EOC; and 5) Conferring chemoresistance in EOC through the exosomal transfer of miRNAs. Conclusion: Research on the exosome and EOC has an increasing trend, and China is much more involved than other countries in research, financial support, and international cooperation. These findings could aid researcher in understanding novel ideas and subjects interested by sponsors in this field.

Photochemical Targeting of Mitochondria to Overcome Chemoresistance in Ovarian Cancer †

Ovarian cancer is the most lethal gynecologic malignancy with a stubborn mortality rate of ~65%. The persistent failure of multiline chemotherapy, and significant tumor heterogeneity, has made it challenging to improve outcomes. A target of increasing interest is the mitochondrion because of its essential role in critical cellular functions, and the significance of metabolic adaptation in chemoresistance. This review describes mitochondrial processes, including metabolic reprogramming, mitochondrial transfer and mitochondrial dynamics in ovarian cancer progression and chemoresistance. The effect of malignant ascites, or excess peritoneal fluid, on mitochondrial function is discussed. The role of photodynamic therapy (PDT) in overcoming mitochondria-mediated resistance is presented. PDT, a photochemistry-based modality, involves the light-based activation of a photosensitizer leading to the production of short-lived reactive molecular species and spatiotemporally confined photodamage to nearby organelles and biological targets. The consequential effects range from subcytotoxic priming of target cells for increased sensitivity to subsequent treatments, such as chemotherapy, to direct cell killing. This review discusses how PDT-based approaches can address key limitations of current treatments. Specifically, an overview of the mechanisms by which PDT alters mitochondrial function, and a summary of preclinical advancements and clinical PDT experience in ovarian cancer are provided.

Turning Adversity into Strength and Transferring It to the Uninitiated: The Tricks Cancer Cells Play to Survive Hypoxic Stress and Fight Chemotherapy

Despite significant progress during the past few decades, cancer remains the second most common cause of death in the US after heart disease [...].

Small extracellular vesicles in metabolic remodeling of tumor cells: Cargos and translational application

Warburg effect is characterized by excessive consumption of glucose by the tumor cells under both aerobic and hypoxic conditions. This metabolic reprogramming allows the tumor cells to adapt to the unique microenvironment and proliferate rapidly, and also promotes tumor metastasis and therapy resistance. Metabolic reprogramming of tumor cells is driven by the aberrant expression and activity of metabolic enzymes, which results in the accumulation of oncometabolites, and the hyperactivation of intracellular growth signals. Recent studies suggest that tumor-associated metabolic remodeling also depends on intercellular communication within the tumor microenvironment (TME). Small extracellular vesicles (sEVs), also known as exosomes, are smaller than 200 nm in diameter and are formed by the fusion of multivesicular bodies with the plasma membrane. The sEVs are instrumental in transporting cargoes such as proteins, nucleic acids or metabolites between the tumor, stromal and immune cells of the TME, and are thus involved in reprogramming the glucose metabolism of recipient cells. In this review, we have summarized the biogenesis and functions of sEVs and metabolic cargos, and the mechanisms through they drive the Warburg effect. Furthermore, the potential applications of targeting sEV-mediated metabolic pathways in tumor liquid biopsy, imaging diagnosis and drug development have also been discussed.

Patients with stage IA ovarian clear cell carcinoma do not require chemotherapy following surgery

BACKGROUND

Ovarian clear cell carcinoma (OCCC) is an infrequent histological subtype of epithelial ovarian cancer (EOC). The present study aimed to investigate whether chemotherapy is indispensable for patients with stage IA OCCC.

METHODS

Data were collected from the Surveillance, Epidemiology and End Results database between 2004 and 2015. All subjects were diagnosed with stage IA OCCC, according to their postoperative pathological reports. In the present study, 1038 patients were retrospectively investigated, among whom 692 patients received chemotherapy. Propensity score matching (PSM) was performed to prevent selection bias. The multivariate Cox proportional hazards model was used to analyze the correlation between variables and 5-year overall survival.

RESULTS

An equal number of patients (n = 346) who did or did not undergo chemotherapy after PSM were further enrolled in the study. The results showed that the mortality of OCCC increased for the patients aged ≥50 years. In addition, older age was associated with lower 5-year overall survival (p < 0.05). However, chemotherapy did not extend the 5-year overall survival (p = 0.524) of patients with stage IA OCCC, according to the multivariate Cox regression analysis.

CONCLUSIONS

Chemotherapy did not affect the overall survival of patients with stage IA OCCC following surgery.

Metabolic reprogramming of the tumor immune microenvironment in ovarian cancer: A novel orientation for immunotherapy

Ovarian cancer is the most lethal gynecologic tumor, with the highest mortality rate. Numerous studies have been conducted on the treatment of ovarian cancer in the hopes of improving therapeutic outcomes. Immune cells have been revealed to play a dual function in the development of ovarian cancer, acting as both tumor promoters and tumor suppressors. Increasingly, the tumor immune microenvironment (TIME) has been proposed and confirmed to play a unique role in tumor development and treatment by altering immunosuppressive and cytotoxic responses in the vicinity of tumor cells through metabolic reprogramming. Furthermore, studies of immunometabolism have provided new insights into the understanding of the TIME. Targeting or activating metabolic processes of the TIME has the potential to be an antitumor therapy modality. In this review, we summarize the composition of the TIME of ovarian cancer and its metabolic reprogramming, its relationship with drug resistance in ovarian cancer, and recent research advances in immunotherapy.

Exosomes Derived from Hypoxic Glioma Cells Reduce the Sensitivity of Glioma Cells to Temozolomide Through Carrying miR-106a-5p

Background

Hypoxia is a frequent feature of solid tumors which significantly affects the efficacy of treatments such as chemotherapy. In addition, exosomes from hypoxic cancer cells could contribute to the chemoresistance of tumor cells through carrying miRNAs. It has been shown that miR-106-5p level was upregulated in glioma. However, whether exosomes derived from hypoxic glioma cells could affect temozolomide (TMZ) resistance in glioma through carrying miR-106a-5p remains unexplored.

Methods

Exosomes were isolated from glioma cells under normoxia or hypoxia condition. EdU staining and flow cytometry assays were used to assess the cell proliferation and cell apoptosis. The relation between miR-106a-5p and PTEN was investigated by dual luciferase assay.

Results

MiR-106a-5p was enriched in exosomes derived from hypoxic glioma cells compared to exosomes from cells under normoxia condition. Additionally, hypoxic glioma cells were able to transfer exosomes to glioma cells, resulting in a significant increase of miR-106a-5p level in cells. TMZ remarkably suppressed glioma cell proliferation and triggered cell apoptosis. However, hypoxic glioma cell-derived exosomes markedly promoted the proliferation and suppressed the apoptosis in TMZ-treated glioma cells, and miR-106a-5p inhibitor was able to abolish these phenomena. Meanwhile, PTEN was verified to be a direct target of miR-106a-5p. Furthermore, TMZ elevated PTEN and Bax level and reduced p-Akt level in glioma cells, whereas these changes were reversed by hypoxia glioma cell-derived exosomes. Furthermore, hypoxia glioma cell-derived exosomes reduced the sensitivity of glioma cells to TMZ in vivo via downregulating PTEN.

Conclusion

Collectively, exosomal miR-106a-5p derived from hypoxia glioma cells could reduce the sensitivity of glioma cells to TMZ through downregulating PTEN. Thus, our study might provide new strategies for improving the clinical efficacy of TMZ on glioma.

Advances in Exosomes as Diagnostic and Therapeutic Biomarkers for Gynaecological Malignancies

Simple Summary

The three major gynaecological cancers are ovarian cancer, endometrial cancer, and cervical cancer, which endanger women’s health worldwide. Significant progress has been made in the study of exosomes, which have been proven to be an important form of intercellular communication, as well as an important carrier for the uptake, transport, and release of cargo. Exosomes may also be promising diagnostic or prognostic markers for gynaecologic malignancies, which may improve the level of treatment of gynaecologic malignancies. This article reviews the latest research progress and systematic knowledge of exosomes in gynaecological malignant tumours in recent years, in order to provide a new perspective for the treatment of gynaecological tumours and promote the clinical application of exosomes in gynaecological malignancies.

Abstract

Background: Exosomes are extracellular vesicles that can be released by practically all types of cells. They have a diameter of 30–150 nm. Exosomes control the exchange of materials and information between cells. This function is based on its special cargo-carrying and transporting functions, which can load a variety of useful components and guarantee their preservation. Recently, exosomes have been confirmed to play a significant role in the pathogenesis, diagnosis, treatment, and prognosis of gynaecological malignancies. Particularly, participation in liquid biopsy was studied extensively in gynaecological cancer, which holds the advantages of noninvasiveness and individualization. Literature Review: This article reviews the latest research progress of exosomes in gynaecological malignancies and discusses the involvement of humoral and cell-derived exosomes in the pathogenesis, progression, metastasis, drug resistance and treatment of ovarian cancer, cervical cancer, and endometrial cancer. Advances in the clinical application of exosomes in diagnostic technology, drug delivery, and overcoming tumour resistance are also presented. Conclusion: Exosomes are potentially diagnostic and prognostic biomarkers in gynaecological malignancies, and also provide new directions for the treatment of gynaecological tumours, showing great clinical potential.

Identification of Novel Hypoxia Subtypes for Prognosis Based on Machine Learning Algorithms

Objective

A reduced level or tension or the deprivation of oxygen is termed hypoxia. It is common for tumours to outgrow their natural source of nutrients, which causes hypoxia in some tumour regions. Hypoxia affects ovarian cancer (OC) in several ways.

Methods

In this study, the expression patterns of prognostic hypoxia-related genes were curated, and consensus clustering analyses were performed to determine hypoxia subtypes in OC included in The Cancer Genome Atlas cohort. Two hypoxia-related subtypes were observed and considered for further investigation. The analyses of differentially expressed genes (DEGs), gene ontology, mutation, and immune cell infraction were performed to explore the underlying molecular mechanisms.

Results

In total, 377 patients with OC were classified into two subgroups based on the subtype of hypoxia. The clinical outcome was considerably poor for patients with hypoxia subtype 2. DEG and protein-protein interaction analyses revealed that the expression levels of CLIP2 and SH3PXD2A were low in OC tissues. Immune cell infarction analysis revealed that the subtypes were associated with the tumour microenvironment (TME).

Conclusion

Our findings established the existence of two distinctive, complex, and varied hypoxia subtypes in OC. Findings from the quantitative analysis of hypoxia subtypes in patients improved our understanding of the characteristics of the TME and may facilitate the development of more efficient treatment regimens.

The hypoxia-driven crosstalk between tumor and tumor-associated macrophages: mechanisms and clinical treatment strategies

Given that hypoxia is a persistent physiological feature of many different solid tumors and a key driver for cancer malignancy, it is thought to be a major target in cancer treatment recently. Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME), which have a large impact on tumor development and immunotherapy. TAMs massively accumulate within hypoxic tumor regions. TAMs and hypoxia represent a deadly combination because hypoxia has been suggested to induce a pro-tumorigenic macrophage phenotype. Hypoxia not only directly affects macrophage polarization, but it also has an indirect effect by altering the communication between tumor cells and macrophages. For example, hypoxia can influence the expression of chemokines and exosomes, both of which have profound impacts on the recipient cells. Recently, it has been demonstrated that the intricate interaction between cancer cells and TAMs in the hypoxic TME is relevant to poor prognosis and increased tumor malignancy. However, there are no comprehensive literature reviews on the molecular mechanisms underlying the hypoxia-mediated communication between tumor cells and TAMs. Therefore, this review has the aim to collect all recently available data on this topic and provide insights for developing novel therapeutic strategies for reducing the effects of hypoxia.

Extracellular vesicle contents as non-invasive biomarkers in ovarian malignancies

Ovarian cancer most commonly presents at an advanced stage where survival is approximately 30% compared with >80% if diagnosed and treated before disease spreads. Diagnostic capabilities have progressed from surgical staging via laparotomy to image-guided biopsies and immunohistochemistry staining, along with advances in technology and medicine. Despite improvements in diagnostic capabilities, population-level screening for ovarian cancer is not recommended. Extracellular vesicles (EVs) are 40–150 nm structures formed when the cellular lipid bilayer invaginates. These structures function in cell signaling, immune responses, cancer progression, and establishing the tumor microenvironment. EVs are found in nearly every bodily fluid, including serum, plasma, ascites, urine, and effusion fluid, and contain molecular cargo from their cell of origin. This cargo can be analyzed to yield information about a possible malignancy. In this review we describe how the cargo of EVs has been studied as biomarkers in ovarian cancer. We bring together studies analyzing evidence for various cargos as ovarian cancer biomarkers. Then, we describe the role of EVs in modulation of the tumor microenvironment. This review also summarizes the therapeutic and translational potential of EVs for their optimal utilization as non-invasive biomarkers for novel treatments against cancer.

Non-Coding RNAs Delivery by Small Extracellular Vesicles and Their Applications in Ovarian Cancer

Ovarian cancer (OC) is the most fatal gynecological malignancy because of its early asymptomatic nature and acquired resistance to chemotherapy. Small extracellular vesicles (sEVs) are a heterogeneous group of biological vesicles with a diameter <200 nm released by cells under physiological or pathological conditions. sEVs-derived non-coding RNAs (ncRNAs) are the essential effectors in the biological environment. sEVs-ncRNAs have critical roles in tumor progression via regulating mRNA expression of target cells to affect cell signaling. In addition, the status of parental cells can be disclosed via analyzing the composition of sEVs-ncRNAs, and their “cargoes” with specific changes can be used as key biomarkers for the diagnosis and prognosis of OC. Accumulating evidence has demonstrated that sEVs-ncRNAs are involved in multiple key processes that mediate the development of metastasis and chemotherapeutic resistance in OC: epithelial–mesenchymal transition; tumorigenicity of mesenchymal stem cells; immune evasion; angiogenesis. The nanomedicine delivery system based on engineering sEVs is expected to be a novel therapeutic strategy for OC. Insights into the biological roles of sEVs-ncRNAs in the invasion, metastasis, immune regulation, and chemoresistance of OC will contribute to discovery of novel biomarkers and molecular targets for early detection and innovative therapy. In this review, we highlight recent advances and applications of sEVs-ncRNAs in OC diagnosis and treatment. We also outline current challenges and knowledge gaps.

The Role of Extracellular Vesicles in Metabolic Reprogramming of the Tumor Microenvironment

The tumor microenvironment (TME) includes a network of cancerous and non-cancerous cells, together with associated blood vessels, the extracellular matrix, and signaling molecules. The TME contributes to cancer progression during various phases of tumorigenesis, and interactions that take place within the TME have become targets of focus in cancer therapy development. Extracellular vesicles (EVs) are known to be conveyors of genetic material, proteins, and lipids within the TME. One of the hallmarks of cancer is its ability to reprogram metabolism to sustain cell growth and proliferation in a stringent environment. In this review, we provide an overview of TME EV involvement in the metabolic reprogramming of cancer and stromal cells, which favors cancer progression by enhancing angiogenesis, proliferation, metastasis, treatment resistance, and immunoevasion. Targeting the communication mechanisms and systems utilized by TME-EVs is opening a new frontier in cancer therapy.

CircRBM33 downregulation inhibits hypoxia-induced glycolysis and promotes apoptosis of breast cancer cells via a microRNA-542-3p/HIF-1α axis

Many circRNAs are involved in the carcinogenesis of breast cancer (BCa) through the transcription of microRNAs (miRNAs) and mRNAs. This study investigated circRBM33 regulation of the miR-542-3p/hypoxia-inducible factor-1α (HIF-1α) axis in BCa. BCa clinical tissue samples were collected to test differential expressions of circRBM33, miR-542-3p, and HIF-1α. MCF-7 cells were subjected to normoxia or hypoxia and transfected with plasmids that regulated CircRBM33, miR-542-3p, and HIF-1α expression levels. Glycolysis was evaluated by measuring glucose consumption, lactic acid production, and protein expression of hexokinase 2, glucose transporter type 1 and lactic dehydrogenase A. Cell proliferation and apoptosis were also assessed, and the interactions between genes were explored. CircRBM33 and HIF-1α were upregulated, while miR-542-3p was downregulated in BCa tissue samples and cell lines. Hypoxia induced circRBM33 expression in BCa cells, which negatively regulated miR-542-3p expression. CircRBM33 knockdown or miR-542-3p rescue reduced glycolysis and proliferation and promoted apoptosis of BCa cells. MiR-542-3p inhibition rescued circRBM33 knockdown-mediated glycolysis, proliferation and apoptosis of BCa cells. MiR-542-3p targeted HIF-1α, and the overexpression of HIF-1α reversed the effect of miR-542-3p upregulation on glycolysis, proliferation, and apoptosis of BCa cells. Collectively, downregulating circRBM33 suppresses miR-542-3p-targeted HIF-1α expression, resulting in the inhibition of glycolysis and proliferation and the promotion of BCa cells’ apoptosis.

Comparing the Secretomes of Chemorefractory and Chemoresistant Ovarian Cancer Cell Populations

High-grade serous ovarian cancer (HGSOC) constitutes the majority of all ovarian cancer cases and has staggering rates of both refractory and recurrent disease. While most patients respond to the initial treatment with paclitaxel and platinum-based drugs, up to 25% do not, and of the remaining that do, 75% experience disease recurrence within the subsequent two years. Intrinsic resistance in refractory cases is driven by environmental stressors like tumor hypoxia which alter the tumor microenvironment to promote cancer progression and resistance to anticancer drugs. Recurrent disease describes the acquisition of chemoresistance whereby cancer cells survive the initial exposure to chemotherapy and develop adaptations to enhance their chances of surviving subsequent treatments. Of the environmental stressors cancer cells endure, exposure to hypoxia has been identified as a potent trigger and priming agent for the development of chemoresistance. Both in the presence of the stress of hypoxia or the therapeutic stress of chemotherapy, cancer cells manage to cope and develop adaptations which prime populations to survive in future stress. One adaptation is the modification in the secretome. Chemoresistance is associated with translational reprogramming for increased protein synthesis, ribosome biogenesis, and vesicle trafficking. This leads to increased production of soluble proteins and extracellular vesicles (EVs) involved in autocrine and paracrine signaling processes. Numerous studies have demonstrated that these factors are largely altered between the secretomes of chemosensitive and chemoresistant patients. Such factors include cytokines, growth factors, EVs, and EV-encapsulated microRNAs (miRNAs), which serve to induce invasive molecular, biophysical, and chemoresistant phenotypes in neighboring normal and cancer cells. This review examines the modifications in the secretome of distinct chemoresistant ovarian cancer cell populations and specific secreted factors, which may serve as candidate biomarkers for aggressive and chemoresistant cancers.

Ovarian-Cancer-Associated Extracellular Vesicles: Microenvironmental Regulation and Potential Clinical Applications

Ovarian cancer (OC) is one of the most diagnosed gynecological cancers in women. Due to the lack of effective early stage screening, women are more often diagnosed at an advanced stage; therefore, it is associated with poor patient outcomes. There are a lack of tools to identify patients at the highest risk of developing this cancer. Moreover, early detection strategies, therapeutic approaches, and real-time monitoring of responses to treatment to improve survival and quality of life are also inadequate. Tumor development and progression are dependent upon cell-to-cell communication, allowing cancer cells to re-program cells not only within the surrounding tumor microenvironment, but also at distant sites. Recent studies established that extracellular vesicles (EVs) mediate bi-directional communication between normal and cancerous cells. EVs are highly stable membrane vesicles that are released from a wide range of cells, including healthy and cancer cells. They contain tissue-specific signaling molecules (e.g., proteins and miRNA) and, once released, regulate target cell phenotypes, inducing a pro-tumorigenic and immunosuppressive phenotype to contribute to tumor growth and metastasis as well as proximal and distal cell function. Thus, EVs are a “fingerprint” of their cell of origin and reflect the metabolic status. Additionally, via the capacity to evade the immune system and remain stable over long periods in circulation, EVs can be potent therapeutic agents. This review examines the potential role of EVs in the different aspects of the tumor microenvironment in OC, as well as their application in diagnosis, delivery of therapeutic agents, and disease monitoring.

Malignant Ascites in Ovarian Cancer: Cellular, Acellular, and Biophysical Determinants of Molecular Characteristics and Therapy Response

Ascites refers to the abnormal accumulation of fluid in the peritoneum resulting from an underlying pathology, such as metastatic cancer. Among all cancers, advanced-stage epithelial ovarian cancer is most frequently associated with the production of malignant ascites and is the leading cause of death from gynecologic malignancies. Despite decades of evidence showing that the accumulation of peritoneal fluid portends the poorest outcomes for cancer patients, the role of malignant ascites in promoting metastasis and therapy resistance remains poorly understood. This review summarizes the current understanding of malignant ascites, with a focus on ovarian cancer. The first section provides an overview of heterogeneity in ovarian cancer and the pathophysiology of malignant ascites. Next, analytical methods used to characterize the cellular and acellular components of malignant ascites, as well the role of these components in modulating cell biology, are discussed. The review then provides a perspective on the pressures and forces that tumors are subjected to in the presence of malignant ascites and the impact of physical stress on therapy resistance. Treatment options for malignant ascites, including surgical, pharmacological and photochemical interventions are then discussed to highlight challenges and opportunities at the interface of drug discovery, device development and physical sciences in oncology.

Characterizing Endocrine Status, Tumor Hypoxia and Immunogenicity for Therapy Success in Epithelial Ovarian Cancer

Epithelial ovarian cancer is predominantly diagnosed at advanced stages which creates significant therapeutic challenges. As a result, the 5-year survival rate is low. Within ovarian cancer, significant tumor heterogeneity exists, and the tumor microenvironment is diverse. Tumor heterogeneity leads to diversity in therapy response within the tumor, which can lead to resistance or recurrence. Advancements in therapy development and tumor profiling have initiated a shift from a "one-size-fits-all" approach towards precision patient-based therapies. Here, we review aspects of ovarian tumor heterogeneity that facilitate tumorigenesis and contribute to treatment failure. These tumor characteristics should be considered when designing novel therapies or characterizing mechanisms of treatment resistance. Individual patients vary considerably in terms of age, fertility and contraceptive use which innately affects the endocrine milieu in the ovary. Similarly, individual tumors differ significantly in their immune profile, which can impact the efficacy of immunotherapies. Tumor size, presence of malignant ascites and vascular density further alters the tumor microenvironment, creating areas of significant hypoxia that is notorious for increasing tumorigenesis, resistance to standard of care therapies and promoting stemness and metastases. We further expand on strategies aimed at improving oxygenation status in tumors to dampen downstream effects of hypoxia and set the stage for better response to therapy.