Background Ovarian cancer (OC) remains a major global health issue, often diagnosed late and lacking effective screening.Methods MR studies until 11 September 2023 were identified by a systematic search across nine databases. We complied with PRISMA guidelines and included different OC subtypes and all exposures studied, conducting meta-analyses where feasible to combine estimates from non-overlapping samples.Results We identified 120 articles examining genetic evidence for an association between 230 exposures and OC risk. Endometriosis, late age at menopause, and several adiposity measures were robustly associated with greater OC risk. In contrast, late age at menarche, higher adiponectin, and body fat without adverse metabolic profile were associated with lower risk (favourable adiposity: meta-analysis OR per SD 0.35, 95% CI 0.20-0.61). Meta-analyses on lipid-lowering drug target HMG-CoA reductase inhibitor (OR 0.66, 95% CI 0.53-0.82), serum vitamin D (OR 0.88, 95% CI 0.82-0.95), and dried fruit intake (HR 0.61, 95% CI 0.41-0.91) were supportive of protective associations.Conclusions Genetic evidence confirms OC risks associated with endometriosis, and age at menarche and menopause. While greater overall adiposity increases the risk, fat without an adverse metabolic profile appears protective. Associations between vitamin D and HMG-CoA reductase inhibition with OC risk warrant further study.

Abstract Background ADAMTS1, a disintegrin and metalloproteinase with thrombospondin motif 1, plays a role in inflammation, organogenesis, and ovulation. Up or downregulation of ADAMTS1 has been implicated in tissue remodelling leading to cancer. We analysed the expression of ADAMTS1 in different stages/grades of primary and metastatic serous ovarian tumours and ascites-derived tumour cells from patients and assessed the functional role of ADAMTS1 in ovarian cancer (OC) cell lines. Methods The expression and localisation of ADAMTS1 was assessed by immunohistochemistry (IHC) and Opal Multiplex IHC staining of OC tissues. Functional roles of ADAMTS1 in OC cell lines were assessed by using siRNA-mediated knockdown (KD), MTT assay, cell migration by xCELLigence, cell adhesion, ELISA, qRT-PCR, Western blot, immunofluorescence (IF) and activity of Cdc42 GTPase. Results The expression of ADAMTS1 was significantly enhanced in higher stages/grades of ovarian tumours compared to benign tumours. In high-grade tumours, ADAMTS1 was localised more in the nucleus of epithelial cells while localisation in stromal cells was mostly in the cytoplasm. Significantly higher mRNA expression of ADAMTS1 was noted in epithelial compared to mesenchymal ascites-derived tumour cells. The expression of ADAMTS1 was significantly higher in metastatic high-grade tumours compared to primary tumours. KD of ADAMTS1 expression by siRNA in OC cell lines had no effect on cell proliferation but resulted in decreased cell adhesion, increased cell migration accompanied by increased expression of markers (CDH1 and EPCAM) associated with epithelial plasticity. Remodelling of ECM accompanied by increased intra- and extracellular production of VCAN and enhanced Cdc42 GTPase activity was also noted in cell lines with ADAMTS1 KD. Cdc42 GTPase specific inhibitor, ML141, reversed ADAMTS1 KD-mediated enhanced migration. On the other hand, VCAN KD inhibited ADAMTS1 KD-mediated migration and reversed the effect on cell adhesion. Conclusions These results suggest that the expression of ADAMTS1 progressively enriches ovarian tumours and promotes OC progression. Its knock down in in vitro cell culture impacts ECM remodelling through enhanced Cdc42GTPase activity and VCAN production resulting in epithelial cell plasticity, accelerated migration, and reduced cell adhesion.

The survival rates of high-grade serous ovarian cancer have not improved in the last three decades, despite extensive research into the molecular determinants of chemoresistance that could inform personalized therapies. This systematic review synthesizes proteomic studies that have used varied sample types, including cell lines, serum, plasma, and ascites, to propose molecular markers of response to treatment regimens consisting of platinum-based chemotherapeutics, taxanes, doxorubicin, and combinations thereof. Gene ontology analyses of differentially expressed proteins across all studies highlight key biological functions, such as heat shock response, cell adhesion, and cell migration. Frequently implicated protein families include keratins, annexins, thioredoxin-related proteins, and SERPINs. We evaluate methodological rigor, orthogonal validation attempts, and adherence to MIAPE data reporting standards to contextualize current knowledge and promote reproducibility in future studies. Collectively, this review underscores proteomics as a promising tool for the prediction of chemotherapy response in high-grade serous ovarian cancer, while emphasizing the need for prospective, standardized approaches that align with data reporting guidelines.

More than 90% of advanced ovarian cancer patients develop malignant ascites, which describes a buildup of fluid in the peritoneal cavity caused by increased vascular permeability and obstructed lymphatic drainage. Malignant ascites contains spheroidal tumor cell clusters that contain stromal cells, cancer-associated fibroblasts, and blood cells. These spheroids promote peritoneal metastasis and treatment resistance, yet the phenotypic and proteomic changes of cells caused by the ascites environment remain poorly understood, as does its influence on ex vivo responses to chemotherapeutics in personalized medicine approaches. Using mass spectrometry, we compared the proteome profiles of cell-free ascites to serum from ovarian cancer patients. We then analyzed the proteomes of immortalized cancer cells grown as monolayers or spheroids in either malignant ascites or standard cell culture medium. The effects of this fluid on the phenotype, molecular composition, and ex vivo chemotherapy responses of cancer cells were also investigated. Proteome analysis revealed that cell-free ascites had higher levels of extracellular, secreted, and membrane proteins compared to serum. Ascites enhanced cell viability and spheroid formation in immortalized ovarian cancer cell lines more effectively than standard cell culture medium. Despite this altered baseline viability, growth of spheroids in ascites versus cell culture medium did not hinder chemotherapy response assessments, indicating the appropriateness of standard cell culture medium in ex vivo applications. The observed phenotypic changes of cells grown in ascites could not be recapitulated by adding chemokines or periostin to the cell culture medium, suggesting that additional factors are required. Notably, elevated levels of transglutaminase 2 were identified in SKOV-3 cells grown in ascites, indicating that ascites directly influences protein expression in cancer cells.

Most advanced ovarian cancer patients develop malignant ascites, which describes a buildup of fluid in the peritoneal cavity caused by increased vascular permeability and obstructed lymphatic drainage. Malignant ascites contains cancer cells, which can aggregate as spheroids, as well as stromal cells, cancer-associated fibroblasts, and blood cells that create a complex tumor microenvironment. This study explores the proteome of ascites and how this environment affects the viability, phenotypes, proteomes, and treatment responses of ovarian cancer cells. Using label-free proteomics, we compared the proteomes of cell-free malignant ascites from ovarian cancer patients with those of serum. Additionally, we examined the ex vivo chemotherapy responses of cancer spheroids cultured in ascites. Through detailed proteomic analysis of cells grown as 2D or 3D in tissue culture medium or ascites, we identified biological pathways and specific proteins induced by ascites. Finally, we performed orthogonal validation of a candidate marker, TGM2, using immunofluorescent staining. Proteomics of cell-free ascites identified increased levels of extracellular, secreted, and membrane proteins when compared to serum. Ascites enhanced the baseline cell viability and spheroid formation of immortalized ovarian cancer cell lines compared to standard cell culture medium. However, chemotherapy-induced cell death of spheroids grown in standard cell culture medium remained proportional to changes observed in ascites-cultured spheroids. Ascites-driven phenotypic changes were not recapitulated by adding selected chemokines nor periostin to the cell culture medium, suggesting that additional factors are required. Notably, ascites induced similar ECM, secreted, and membrane proteins across 2D and 3D models, including TGM2, which was validated in spheroids through immunofluorescent staining. This study contributes to our understanding of the role of ascites in the regulation of the proteome and viability of cancer cells. It provides evidence for the induction of TGM2 expression by ascites. Results from this pilot study warrant further study in a larger cohort.

Genetic heterogeneity in ovarian cancer drives frequent aberrant expression of cell surface proteins including G-protein coupled receptors (GPCRs), which harbour untapped potential for active targeting with nanomedicines. Our goal was to systematically identify GPCRs with significant overexpression in ovarian cancer biopsies and assessing their suitability to develop personalized GPCR-targeted nanomedicines for precise drug delivery. We ran a systematic analysis of public RNA-seq gene expression data, to reveal GPCRs with frequent overexpression in ovarian cancer tissues. To validate the relevance of initially identified receptors as targeting candidates, we confirmed their expression in six ovarian cancer cell lines and a selection of patient-derived samples (ascites derived tumour samples and solid tumours), using techniques such as RT-qPCR, flow cytometry, fluorescence imaging and immunofluorescence. This comprehensive analysis provided valuable insights into the prevalence and distribution of candidate receptors across different ovarian cancer probes. Furthermore, we utilized representative ovarian cancer cell lines as in vitro models to assess receptor-mediated cellular uptake and internalization processes, to further evaluate potential targets for nanoparticle delivery systems. Analysis of public RNA-Seq datasets revealed 13 overexpressed GPCRs in cancer tissues compared to healthy tissues. Among these, we focused specifically on the coagulation factor II thrombin receptor (F2R) to highlight its intriguing potential as a therapeutic target. The variable expression of F2R was confirmed in both ovarian cancer cell lines and patient-derived samples. Furthermore, peptide binding to the receptor was successfully demonstrated using flow cytometry and fluorescent imaging, suggesting a promising approach for targeted drug delivery. and Significance: Our findings underscore the importance of personalized targeting approaches in ovarian cancer therapy and highlight the potential of F2R as a promising therapeutic target. By integrating advanced molecular techniques with nanomedicine strategies, we strive to pave the way for more effective and tailored treatments for ovarian cancer patients. Riya Khetan, Preethi Eldi, Noor Lokman, Carmela Ricciardelli, Martin Oehler, Anton Blencowe, Katherine Pillman, Sanjay Garg, Hugo Albrecht. Leveraging GPCR overexpression for personalized nanomedicine: A novel approach in ovarian cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5995.

Cyclin E1 positive protein expression comprises a significant portion of patients with platinum resistant ovarian cancer (PROC) and has been associated with poor prognosis in ovarian cancer patients. Currently, there are no approved therapies specifically for cyclin E1 positive-PROC, presenting a significant unmet need. Azenosertib is a potential best-in-class, highly selective oral WEE1 kinase inhibitor. Cyclin E1 protein overexpression has been shown to directly correlate with an increased reliance on the G2/M checkpoint in the cell cycle and is a predictive biomarker of azenosertib sensitivity in preclinical models of ovarian cancer (Kim D, et al. NPJ Precis Oncol. 2025;9[1]:3). Azenosertib demonstrated clinically meaningful response rates and duration of response in heavily pretreated patients with cyclin E1 positive-PROC in DENALI Part 1b (Simpkins F, et al. SGO Annual Meeting 2025: Abstract 814654). In addition, azenosertib has shown to have a manageable safety profile with a low rate of serious treatment-related adverse events.These results indicate that cyclin E1 protein expression is a clinically relevant biomarker associated with response to azenosertib monotherapy, warranting further investigation with azenosertib in patients with cyclin E1 positive-PROC. The objective of DENALI Part 2 is to evaluate the efficacy and safety of azenosertib in patients prospectively screened and selected for cyclin E1 positive-PROC status based on Sponsor’s central immunohistochemistry (IHC) assay. DENALI (NCT05128825, GOG-3066) is a Phase 2 open-label, multicenter, 2-part (Part 1b & Part 2a/b) study assessing the safety and efficacy of azenosertib in patients with PROC (including fallopian tube and primary peritoneal). In Part 2 of the study, which is currently enrolling, eligible patients are required to have measurable disease per RECIST v1.1, cyclin E1 positive-PROC by IHC per Sponsor’s central assay (pre-screening can be performed during current therapy), and ECOG PS 0-1. Prior therapy requirements include bevacizumab, PARPi for patients harboring BRCA 1/2 mutation or HRD, and mirvetuximab for patients with high folate receptor alpha expression. Between 1-3 prior lines of therapy are permitted; a 4th prior line is permitted for patients treated with prior mirvetuximab. In the dose confirmation portion of the study (Part 2a), patients with Cyclin E1 positive-PROC are being randomized 1:1 to receive either azenosertib 300 mg or 400 mg once a day (target enrollment of approximately 30 patients at each dose) on an intermittent schedule (5 days on 2 days off). Upon dose confirmation in Part 2a, Part 2b will continue enrollment of patients at the confirmed Part 2a dose, targeting approximately 100 patients across Part 2a and 2b combined. The endpoints are objective response rate, duration of response, progression-free survival and clinical benefit rate by RECIST v1.1, CA-125 response by Gynecologic Cancer Intergroup criteria, and safety. An Independent Data Monitoring Committee has been chartered for this study. Alexandra Leary, Lyndsay Willmott, Bradley J. Monk, Jean-Sébastien Frenel, David C. Starks, Meena Okera, Angeles Alvarez Secord, David M. O’Malley, Lainie Martin, Kaissa Ouali, Martin K. Oehler, Jeffrey C. Goh, Brian M. Slomovitz, Peter C. Lim, Catherine M. Shannon, Robert Neff, Floor J. Backes, Divya Rajendran, Heekyung Chung, Doris Kim, Hailun Li, Danielle Jandial, Fiona Simpkins. Cyclin E1 Positive Protein Status is a Predictive Biomarker of Azenosertib Benefit in Platinum-Resistant Ovarian Cancer: Part 2 of the DENALI Study (GOG-3066) [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr B013.

The accumulation of malignant ascites in the peritoneal cavity is a hallmark of high-grade serous ovarian cancer (HGSC). This fluid contains three-dimensional multicellular aggregates known as spheroids, which contribute to chemoresistance and are an accessible source of tumor material for proteomic-based biomarker discovery studies. Although heterogeneous ascitic spheroids can be generated from primary cell suspensions for ex vivo applications, they suffer from long generation times and reduced biological relevance. Here, we compare their ex vivo chemotherapy responses and proteomes to native spheroids that are collected directly from HGSC ascites, with the aim of assessing their suitability for proteomic-based chemoresponse prediction strategies that yield results within a clinically relevant time frame. We demonstrate that the chemoresponses of native spheroids better correlate with patients’ clinical treatment responses in 4 of 5 cases and that their proteomes uniquely segregate according to ex vivo carboplatin response along the first component. This pilot study suggests key proteins and biological pathways that may facilitate a global proteomic-based screening strategy for personalized HGSC treatment, with particular emphasis on extracellular matrix proteins. As such, native spheroids have the potential to progress the personalized treatment of HGSC patients with malignant ascites.

Cancer stem cells play an important role in tumor progression and chemotherapy resistance. Leucine-rich G repeat-containing protein-coupled receptor 5 (LGR5) has been identified as a cancer stem cell marker in several cancer types. LGR5 is involved in cancer development and progression via several pathways including WNT/β-catenin signaling pathway. LGR5 plays a role in tumor progression by promoting cancer cell migration, invasion, metastasis, and angiogenesis in many cancers including colorectal, brain, gastric, and ovarian cancer. This review summarises the current knowledge on the expression and functional role of LGR5 in cancers, the molecular mechanisms regulated by LGR5, and the relationship between LGR5 and chemotherapy resistance. The review also includes highlights potential strategies to inhibit LGR5 expression and function. The majority of functional studies have shown that LGR5 plays an important role in promoting cancer progression, metastasis and chemotherapy resistance however, in some contexts LGR5 can also activate tumor-suppressive pathways and LGR5 negative cells can also promote cancer progression. The review highlights that targeting LGR5 is a promising anti-cancer treatment but the functional effect of LGR5 on tumor cells is complex may be dependent on cancer type, tumor microenvironment and cross-talk with other molecules in the LGR5 signaling pathway.

ObjectiveOvarian cancer is characterized by late-stage diagnoses and poor prognosis. We aimed to identify factors that can inform prevention and early detection of ovarian cancer.MethodsWe used a data-driven machine learning approach to identify predictors of epithelial ovarian cancer from 2920 input features measured 12.6 years (IQR 11.9 to 13.3 years) before diagnoses. Analyses included 221 732 female participants in the UK Biobank without a history of cancer. During the follow-up 1441 women developed ovarian cancer. For factors that contributed to model prediction, we used multivariate logistic regression to evaluate the association with ovarian cancer, with evidence for causality tested by Mendelian randomization (MR) analyses in the Ovarian Cancer Genetics Consortium (25 509 cases).ResultsGreater parity and ever-use of oral contraception were associated with lower ovarian cancer risk (ever vs never OR 0.74, 95% CI 0.66 to 0.84). After adjustment for established risk factors, greater height, weight, and greater red blood cell distribution width were associated with increased ovarian cancer risk, while higher aspartate aminotransferase levels and mean corpuscular volume were associated with lower risk. MR analyses confirmed observational associations with anthropometric/adiposity traits (eg, body fat percentage per standard deviation (SD); OR inverse-variance weighted (ORIVW) 1.28, 95% CI 1.13 to 1.46) and aspartate aminotransferase (ORIVW0.87, 95% CI 0.78 to 0.98). MR also provided genetic evidence for a protective association of higher total serum protein on ovarian cancer, higher lymphocyte count on serous and endometrioid ovarian cancer, and greater forced expiratory volume in 1 s on serous ovarian cancer among other findings.ConclusionsThis study shows that certain risk factors for ovarian cancer are modifiable, suggesting that weight reduction and interventions to reduce the number of ovulations may provide potential for future prevention. We also identified blood biomarkers associated with ovarian cancer years before diagnoses, warranting further investigation.

Effective treatment of ovarian cancer is limited by late-stage detection and chemotherapy resistance. There is a clinical need for the discovery of novel molecular targets to enable the development of innovative theranostic approaches. We investigated the coagulation factor II receptor (F2R/PAR1) as a potential diagnostic/prognostic biomarker and therapeutic target for ovarian cancer treatment. Public RNA-sequence and DNA microarray data were used to analyze F2R gene expression in ovarian cancers, with protein expression confirmed in tumor samples by flow cytometry, immunofluorescence and immunohistochemistry (IHC). Functional assays were conducted to study effects of F2R suppression on tumor progression. Our analysis confirmed elevated F2R mRNA and protein expression in ovarian cancers, notably in patients with metastatic and chemotherapy resistant disease. Kaplan-Meier survival analysis demonstrated an association between high F2R protein detection and reduced progression-free survival. F2R suppression in ovarian cancer cell lines reduced tumor cell motility, invasion, spheroid formation, metabolism and enhanced carboplatin sensitivity. F2R is a compelling diagnostic/prognostic and therapeutic target, which could be used to treat chemotherapy resistant and metastatic disease. The evaluation of novel F2R targeting strategies, using antibody conjugated drugs or F2R ligand decorated drug carriers, could lead to the development of effective therapeutics for patients with ovarian cancer. Riya Khetan, Noor A. Lokman, Preethi Eldi, Zoe K. Price, Martin K. Oehler, Doug A. Brooks, Anton Blencowe, Sanjay Garg, Carmela Ricciardelli, Hugo Albrecht. Protease-activated receptor F2R/PAR1 is a potential target for new diagnostic/prognostic and treatment applications for patients with ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr A036.

BACKGROUND:Pelvic exenteration (PE) is a major procedure typically performed for patients with locally advanced or recurrent pelvic malignancy. Appropriate patient selection is crucial to achieving good outcomes and obviating futile resections. The objective of this study was to establish the incidence and predictors of futile PE in patients with locally advanced or recurrent pelvic malignancy. METHODS:A retrospective analysis of a prospective database of patients undergoing PE for advanced or recurrent pelvic malignancy between 2008 and 2025 was performed. Patients with benign disease or less than 6 months' follow-up were excluded, except those who died or recurred within 6 months, who were classified as futile PE. Futility in planned R0 (curative) resections was defined as death from any cause or recurrence (local or distant) within 6 months. Futility in planned R1/R2 (palliative) resections was defined as death from any cause within 6 months. Multivariable logistic regression was performed to identify predictors of futile PE. RESULTS:Of 224 patients identified, 172 were eligible for inclusion in the study and 25 (14.5 %) patients had a futile resection criteria. Multivariable analysis demonstrated Systemic Inflammation Response Index (SIRI ≥1.92) (OR, 7.06; 95 % CI, 1.58-31.57; P = 0.011) and cancer site (non-colorectal cancer) (OR, 4.68; 95 % CI, 1.81-12.10; P = 0.001) as independent risk factors for futile surgery. CONCLUSION:Futile PE was observed in 14.5 % of patients. Key predictors of futility included non-colorectal cancers and elevated preoperative SIRI levels.

Ovarian cancer is the most lethal gynecological cancer. Up to 75% of cases are high-grade serous ovarian cancer (HGSOC) that have high chemosensitivity to first-line platinum-based therapies. However, 75% of patients will become chemoresistant following relapse. The underlying mechanism for developing resistance to chemotherapy in HGSOC is poorly understood. In this study, we employed Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging (MALDI-MSI) on matching formalin-fixed paraffin-embedded (FFPE) HGSOC tissues at the time of diagnosis and following relapse with chemotherapy-resistant disease (n = 4). We identified m/z values that were differentially abundant in the matching diagnosis and relapse HGSOC tissues. These were matched to proteins using nano-liquid chromatography tandem mass spectrometry (LC-MS/MS). We identified upregulated proteins in the HGSOC relapse tissues, including COL12A1, FUBP1, PLEC, SLC4A1, and TKT. These proteins were validated by immunohistochemistry (IHC) and gene expression using online databases. IHC showed COL12A1, FUBP1, PLEC, SLC4A1, and TKT protein abundance were significantly elevated in HGSOC relapse tissues compared to matching tissues at diagnosis. COL12A1, FUBP1, PLEC, and TKT mRNA expression levels were significantly increased in HGSOC compared to normal ovary and associated with poor prognosis in HGSOC. We confirmed that higher protein abundance of both COL12A1 and PLEC correlated with reduced progression-free survival in HGSOC patients. Furthermore, both COL12A1 and PLEC mRNA and protein levels were significantly associated with chemotherapy resistance. In summary, using MALDI-MSI, we have identified proteins, including COL12A1 and PLEC, associated with chemotherapy resistance to be further evaluated as HGSOC biomarkers and/or therapeutic targets.

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The effects of hyaluronan (HA) in cancer are widely studied; however, the role of different molecular weight HA is poorly understood. Identifying novel proteins regulated by different molecular weight HA may highlight novel therapeutic targets. Proteomics analysis was performed to identify novel proteins regulated by different molecular weight HA (27, 183 and 1000 kDa) in ES-2 ovarian cancer cells over-expressing Notch3 intra-cellular domain. Our analyses identified sphingosine kinase 1 (SPHK1), a novel protein regulated by 183- and 1000-kDa HA. Utilising online databases and high-grade serous ovarian cancer (HGSOC) patient tissue microarray cohorts, we assessed the relationship between SPHK1 expression and ovarian cancer metastasis, recurrence and patient outcome. We assessed the effects of the HA synthesis inhibitor 4-methylumbelliferone (4-MU) on SPHK1 expression in ovarian cancer cells and HGSOC patient tissues using ex vivo tissue explant assays. SPHK1 was significantly increased in ovarian cancer compared to normal tissues, elevated in metastatic and recurrent HGSOC tissues and associated with poor patient outcome. 4-MU significantly inhibited SPHK1 expression in ovarian cancer cells (ES-2, CaOV3 and A2780) and HGSOC patient tissues. This study highlights a link between HA and SPHK1 expression in ovarian cancer. Our findings confirm an adverse effect on ovarian cancer prognosis. SPHK1 constitutes a novel promising target against ovarian cancer that warrants further investigation.

Effective treatment of ovarian cancer is limited by late-stage detection and chemotherapy resistance. There is a clinical need for the discovery of novel molecular targets to enable the development of innovative theranostic approaches. We investigated the coagulation factor II receptor/protease-activated receptor 1 (F2R/PAR1) as a potential diagnostic/prognostic biomarker and therapeutic target for ovarian cancer treatment. Public RNA sequence and DNA microarray data were used to analyze F2R gene expression in ovarian cancers, with protein expression confirmed in tumor samples by flow cytometry, immunofluorescence, and immunohistochemistry (IHC). Functional assays were conducted to study effects of F2R suppression on tumor progression. Our analysis confirmed elevated F2R mRNA and protein expression in ovarian cancers, notably in patients with metastatic and chemotherapy-resistant disease. Kaplan-Meier survival analysis demonstrated an association between high F2R protein detection and reduced progression-free survival. F2R suppression in ovarian cancer cell lines reduced tumor cell motility, invasion, spheroid formation, and metabolism and enhanced carboplatin sensitivity. F2R is a compelling diagnostic/prognostic and therapeutic target that could be used to treat chemotherapy-resistant and metastatic disease. The evaluation of novel F2R targeting strategies, using antibody-conjugated drugs or F2R ligand-decorated drug carriers, could lead to the development of effective therapeutics for patients with ovarian cancer.

This study characterised the proteins from EVs in the serum from high-grade serous ovarian cancer (HGSOC) compared to healthy controls. Serum EVs were isolated, followed by label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify differentially expressed proteins. We validated the expression of 4 EV proteins increased in cancer serum (KRT4, MARCKS, SPP1/OPN, and UCHL1) in HGSOC tissues and normal ovarian tissues using online databases and independent HGSOC patient tissue cohorts. We additionally investigated the effects of the UCHL1 inhibitor, LDN-57444, on HGSOC cell metabolic activity, motility, invasion, and apoptosis in HGSOC tissues using patient-derived explant assays. Proteomics analysis identified 28 EV proteins that were upregulated in HGSOC compared to healthy controls. We confirmed that UCHL1 protein levels were increased in HGSOC tissues compared to normal (OSE and FT) and benign epithelium. High stromal UCHL1 levels were associated with reduced progression-free survival in HGSOC. The UCHL1 inhibitor, LDN-57444, reduced the cell metabolic activity of ovarian cancer cell lines and primary ovarian cancer cells with high UCHL1 levels. LDN-57444 blocked the motility and invasion of OVCAR3 cells and promoted apoptosis in the HGSOC patient explant tissue assay. UCHL1 has the potential to be used as a novel prognostic and therapeutic target for HGSOC.