Peritoneal Metastasis Of Ovarian Cancer Research Articles

Angiopoietin-like protein 2 decreases peritoneal metastasis of ovarian cancer cells by suppressing anoikis resistance

Peritoneal metastasis is a common mode of spread of ovarian cancer. Despite therapeutic advances, some patients have intractable peritoneal metastasis. Therefore, in-depth characterization of the molecular mechanism of peritoneal metastasis is a key imperative. Angiopoietin-like protein 2 (ANGPTL2) is an inflammatory factor which activates NF-κB signaling and plays an important role in the pathogenesis of various inflammatory diseases including cancers, such as lung and breast cancer. In this study, we examined the role of ANGPTL2 in ovarian cancer peritoneal metastasis. We observed no difference of cell proliferation between ANGPTL2-expressing and control cells. In the mouse intraperitoneal xenograft model, formation of peritoneal metastasis by ANGPTL2-expressing cells was significantly decreased compared to control. In the in vitro analysis, the expressions of integrin α5β1, α6, and β4, but not those of αvβ3, α3, α4, and β1, were significantly decreased in ANGPTL2-expressing cells compared to control cells. ANGPTL2-expressing cells showed significantly inhibited adherence to laminin compared to control. In addition, we observed upregulation of anoikis (a form of programmed cell death occurring under an anchorage-independent condition) and significant decrease in the expression of Bcl-2 in ANGPTL2-expressing cells as compared to control cells. These results suggest that ANGPTL2 expression in ovarian cancer cells represses peritoneal metastasis by suppressing anoikis resistance.

Ovarian Carcinoma with Peritoneal Metastasis: Rethinking of Management

Epithelial Ovarian Carcinoma (EOC), a type of cancer that is usually diagnosed in advanced stages. To date, standard treatment of EOC is surgery with neoadjuvant or adjuvant platin and taxane based systemic chemotherapy. Hyperthermic intraoperative intraperitoneal chemotherapy (HIPEC) is considered in cases of recurrence of EOC. HIPEC has been accepted as a gold standart for the treatment of pseudomyoxoma peritonei of ovarian and appendiceal origin. More recently, a randomized clinical trial supports that HIPEC is a promising treatment option for peritoneal metastasis (PM) of ovarian cancer (OC) in surgical series. HIPEC is also reported to be an effective treatment option in primary and recurrent cancer cases with PM of OC. As a result, the standardization and optimization of the HIPEC technique, determination of patient subgroups with PM of the OC responding to treatments, personalized evaluation and the treatments currently carried out by the multidisciplinary team still need to be re-evaluated.
 In this review, it is aimed to update the standard treatment approach in case of peritoneal metastasis of ovarian cancer, along with the systemic treatments and HIPEC treatment approaches combined with surgery.

LncRNA SPOCD1-AS from ovarian cancer extracellular vesicles remodels mesothelial cells to promote peritoneal metastasis via interacting with G3BP1

BackgroundMetastasis is the key cause of death in ovarian cancer patients. To figure out the biological nature of cancer metastasis is essential for developing effective targeted therapy. Here we investigate how long non-coding RNA (lncRNA) SPOCD1-AS from ovarian cancer extracellular vesicles (EVs) remodel mesothelial cells through a mesothelial-to-mesenchymal transition (MMT) manner and facilitate peritoneal metastasis.MethodsEVs purified from ovarian cancer cells and ascites of patients were applied to mesothelial cells. The MMT process of mesothelial cells was assessed by morphology observation, western blot analysis, migration assay and adhesion assay. Altered lncRNAs of EV-treated mesothelial cells were screened by RNA sequencing and identified by qRT-PCR. SPOCD1-AS was overexpressed or silenced by overexpression lentivirus or shRNA, respectively. RNA pull-down and RNA immunoprecipitation assays were conducted to reveal the mechanism by which SPOCD1-AS remodeled mesothelial cells. Interfering peptides were synthesized and applied. Ovarian cancer orthotopic implantation mouse model was established in vivo.ResultsWe found that ovarian cancer-secreted EVs could be taken into recipient mesothelial cells, induce the MMT phenotype and enhance cancer cell adhesion to mesothelial cells. Furthermore, SPOCD1-AS embedded in ovarian cancer-secreted EVs was transmitted to mesothelial cells to induce the MMT process and facilitate peritoneal colonization in vitro and in vivo. SPOCD1-AS induced the MMT process of mesothelial cells via interacting with G3BP1 protein. Additionally, G3BP1 interfering peptide based on the F380/F382 residues was able to block SPOCD1-AS/G3BP1 interaction, inhibit the MMT phenotype of mesothelial cells, and diminish peritoneal metastasis in vivo.ConclusionsOur findings elucidate the mechanism associated with EVs and their cargos in ovarian cancer peritoneal metastasis and may provide a potential approach for metastatic ovarian cancer therapeutics.

Targeting eukaryotic elongation factor-2 kinase suppresses the growth and peritoneal metastasis of ovarian cancer

Ovarian cancer (OC) is the deadliest gynecological cancer and is currently incurable with standard treatment regimens. Early invasion, intraperitoneal metastasis, and an aggressive course are the hallmarks of OC. The major reason for poor prognosis is a lack of molecular targets and highly effective targeted therapies. Therefore, identification of novel molecular targets and therapeutic strategies is urgently needed to improve OC survival. Herein we report that eukaryotic elongation factor-2 kinase (EF2K) is highly upregulated in primary and drug-resistant OC cells and its expresssion associated with progression free survival TCGA database) and promotes cell proliferation, survival, and invasion. Downregulation of EF2K reduced expression of integrin β1 and cyclin D1 and the activity of the Src, phosphoinositide 3-kinase/AKT, and nuclear factor-κB signaling pathways. Also, in vivo, therapeutic targeting of EF2K by using single-lipid nanoparticles containing siRNA led to substantial inhibition of ovarian tumor growth and peritoneal metastasis in nude mouse models. Furthermore, EF2K inhibition led to robust apoptosis and markedly reduced intratumoral proliferation in vivo in ovarian tumor xenografts and intraperitoneal metastatic models. Collectively, our data suggest for the first time that EF2K plays an important role in OC growth, metastasis, and progression and may serve as a novel therapeutic target in OCs.

Establishment of a Mouse Ovarian Cancer and Peritoneal Metastasis Model to Study Intraperitoneal Chemotherapy

Simple SummaryIntraperitoneal chemotherapy (IPC) is a locoregional treatment option in patients with peritoneal metastases (PM). Small animal models are valuable research tools allowing for rapid, reproducible, and inexpensive study and optimization of different forms of IPC. Here, we present a mouse model of ovarian cancer-derived PM and demonstrate its suitability for various modes of IPC, including pressurized intraperitoneal chemotherapy (PIPAC) using a micro-nozzle for aerosolized drug delivery.Intraperitoneal chemotherapy (IPC) is a locoregional treatment option in patients with peritoneal metastases (PM). Here, we present an ovarian cancer (OC)-derived PM mouse model for the study of different forms of IPC. Xenograft cell proliferation (luciferase-transfected OVCAR3 and SKOV3 clones) and growth kinetics were assessed using PET scan, bioluminescence imaging (BLI), and histological tumor analysis. Liquid IPC was achieved by intraperitoneal injection with/without capnoperitoneum (6–7 mmHg). Pressurized intraperitoneal aerosol chemotherapy (PIPAC) was mimicked using an intratracheal drug aerosol administration system (micro-nozzle), which, as demonstrated by ex vivo granulometric analysis using laser diffraction spectrometry, produced a polydisperse, bimodal aerosol with a volume-weighted median diameter of (26.49 ± 2.76) µm. Distribution of Tc-99m-labeled doxorubicin in mice was characterized using SPECT and was dependent on the delivery mode and most homogeneous when the micro-nozzle was used. A total of 2 mg doxorubicin per kg body weight was determined to be the optimally effective and tolerable dose to achieve at least 50% tumor reduction. Repeated PIPAC (four times at seven-day-intervals) with doxorubicin in SKOV3-luc tumor-bearing mice resulted in halted tumor proliferation and tumor load reduced after the second round of PIPAC versus controls and the number of tumor nodules was significantly reduced (27.7 ± 9.5 vs. 57.3 ± 9.5; p = 0.0003). Thus, we established the first mouse model of OC PM for the study of IPC using a human xenograft with SKOV3 cells and an experimental IPC setup with a miniaturized nozzle. Repeated IPC was feasible and demonstrated time-dependent anti-tumor activity.

Radiotheranostic Agent 64Cu-cyclam-RAFT-c(-RGDfK-)4 for Management of Peritoneal Metastasis in Ovarian Cancer.

Ovarian cancer peritoneal metastases (OCPMs) are a pathophysiologically heterogeneous group of tumors that are rarely curable. αVβ3 integrin (αVβ3) is overexpressed on tumoral neovessels and frequently on ovarian cancer cells. Here, using two clinically relevant αVβ3-positive OCPM mouse models, we studied the theranostic potential of an αVβ3-specific radiopeptide, 64Cu-cyclam-RAFT-c(-RGDfK-)4 (64Cu-RaftRGD), and its intra- and intertumoral distribution in relation to the tumor microenvironment. αVβ3-expressing peritoneal and subcutaneous models of ovarian carcinoma (IGR-OV1 and NIH:OVCAR-3) were established in nude mice. 64Cu-RaftRGD was administered either intravenously or intraperitoneally. We performed intratumoral distribution (ITD) studies, PET/CT imaging and quantification, biodistribution assay and radiation dosimetry, and therapeutic efficacy and toxicity studies. Intraperitoneal administration was an efficient route for targeting 64Cu-RaftRGD to OCPMs with excellent tumor penetration. Using the fluorescence surrogate, Cy5.5-RaftRGD, in our unique high-resolution multifluorescence analysis, we found that the ITD of 64Cu-RaftRGD was spatially distinct from, but complementary to, that of hypoxia. 64Cu-RaftRGD-based PET enabled clear visualization of multiple OCPM deposits and ascites and biodistribution analysis demonstrated an inverse correlation between tumor uptake and tumor size (1.2-17.2 mm). 64Cu-RaftRGD at a radiotherapeutic dose (148 MBq/0.357 nmol) showed antitumor activities by inhibiting tumor cell proliferation and inducing apoptosis, with negligible toxicity. Collectively, these results demonstrate the all-in-one potential of 64Cu-RaftRGD for imaging guided radiotherapy of OCPM by targeting both tumoral neovessels and cancerous cells. On the basis of the ITD finding, we propose that pairing αVβ3- and hypoxia-targeted radiotherapies could improve therapeutic efficacy by overcoming the heterogeneity of ITD encountered with single-agent treatments.

Paclitaxel increases sensitivity of SKOV3 cells to hyperthermia by inhibiting heat shock protein 27

Hyperthermic intraperitoneal chemotherapy (HIPEC) is a promising treatment strategy for patients with peritoneal metastasis of ovarian cancer. Heat shock proteins (HSPs) play an important role in cellular stress during HIPEC treatment. The aim of the present study was to investigate whether paclitaxel can exert antitumor effects by inhibiting heat shock protein 27 (HSP27) expression during HIPEC treatment. Cell viability was detected by CCK8 assay. We used Western blot analysis to detect HSP27 expression under hyperthermia conditions with or without paclitaxel in SKOV3 cells. To further examine the role of HSP27 in the apoptosis, Bcl-2, Bax and Caspase-3 protein expression were additionally determined after reducing HSP27 levels using an siRNA strategy, and apoptosis was detected using the Annexin V/PI assay. The upregulation of HSP27 expression was accompanied with a rise in temperature. In addition, HSP27 could promote Bcl-2 expression, inhibit Bax and Caspase-3 expression, reduce the Bax / Bcl-2 ratio markedly in SKOV3 cells. Furthermore, paclitaxel could upregulate the Bax / Bcl-2 ratio by inhibiting HSP27 expression, and in turn, promoting apoptosis due to hyperthermia. Paclitaxel could also promote apoptosis by inhibiting HSP27 in SKOV3 cells. Our results demonstrate a synergistic effect between paclitaxel and hyperthermia at the cellular level.

Abstract 5357: Total abdominal ultra-rapid FLASH irradiation enhances the efficacy of PD-1 inhibition in preclinical models of ovarian cancer

Abstract Objective: Ovarian cancer often presents with advanced stage disease. Despite surgery and chemotherapy, recurrence remains inevitable and prognosis poor. Advances in immunotherapy including programmed cell death-1 (PD-1) inhibition show promise, however clinical trials show modest response rates as a single agent therapy in ovarian cancer patients. Radiation therapy is an attractive strategy to enhance the efficacy of immune checkpoint blockade in ovarian cancer due to its ability to increase tumor-infiltrating lymphocytes and enhance immune activation. While ovarian cancer is known to be radiosensitive, total abdominal radiation is not routinely utilized due to high abdominopelvic toxicity. We have recently shown that ultra-high dose rate FLASH irradiation reduces intestinal radiation-induced toxicity. Importantly, we demonstrated efficient tumor control in preclinical models of ovarian cancer peritoneal metastasis. Here we sought to determine the efficacy and safety of FLASH irradiation combined with PD-1 inhibition in preclinical models of ovarian cancer. Methods: Female C57BL/6 mice were intraperitoneally inoculated with ID8-Asc or UPK10 ovarian cancer cells. Total abdominal FLASH irradiation at 14 Gy was administered 10 days post-inoculation. Anti-PD-1 and isotype control antibodies were injected on days 7, 10, and 13 post-inoculation. Mice were sacrificed 22-27 days post-inoculation for tumor burden and immune cell analysis. Stool count, stool weight, complete blood count, and survival were evaluated to compare acute and chronic toxicity as well as efficacy in the treatment arms. Results: Four cohorts of mice were analyzed: Isotype control antibody (IgG), anti-PD-1 (aPD-1), FLASH + IgG, and FLASH + aPD-1. In the ID8-Asc model, irradiated mice showed a 44% decrease in solid stool production with subsequent recovery to baseline by 14 days post-treatment. There was no evidence of hematopoietic toxicity in any of the treatment arms. Survival analysis is ongoing. Exploratory necropsy demonstrated significant tumor burden control in the FLASH cohorts, and in particular, a 25-fold decrease in tumor number in the FLASH + aPD-1 cohort compared to control (mean tumor weight 1.82 mg vs. 357.2 mg, respectively). FLASH + aPD-1 increased intratumoral CD4+ and CD8+ T cells and correlated with enhanced tumor control compared to FLASH or aPD-1 single agent treatments. Similar results were observed in the UPK10 model. Conclusion: Combination FLASH and PD-1 inhibition enhanced tumor control and recruitment of tumor infiltrating lymphocytes compared to IgG, aPD-1, and FLASH treatments alone, while demonstrating safety and tolerability. Our data identify a new opportunity for FLASH and checkpoint inhibition in the treatment of ovarian cancer. Citation Format: Stephanie Chow, Joshua T. Eggold, Karen Levy, Jinghui Wang, Rakesh Manjappa, Dylan Y. Breitkreutz, Amy S. Yu, Karl Bush, Oliver Dorigo, Billy W. Loo, Erinn B. Rankin. Total abdominal ultra-rapid FLASH irradiation enhances the efficacy of PD-1 inhibition in preclinical models of ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5357.

Cyclin H predicts the poor prognosis and promotes the proliferation of ovarian cancer

BackgroundCell cycle dysregulation plays a key role in the pathogenesis of malignant tumors. As a part of the CDK-activating kinase (CAK) trimeric complex, cyclin H is necessary to regulate the cell cycle and proliferation. This investigation aims to characterize the clinical significance and the biological functions of cyclin H in ovarian cancer.MethodsImmunohistochemical staining was performed on 60 ovarian cancer cases, and a correlation between cyclin H expression and the clinical characteristics of ovarian cancer was analyzed. The function of cyclin H in ovarian cancer was further explored using HO8910 cells and a subcutaneous xenograft model of nude mice.ResultCyclin H was slightly expressed in grade 1 ovarian cancer but highly expressed in grade 2 and grade 3 cancerous tissues. The Spearman’s rank correlation analysis showed that the expression of cyclin H is positively correlated with the tumor grade, the FIGO stage, histological grade, and the peritoneal metastasis of ovarian cancer and is also positively correlated with the Ki67 and p-CDK2 in ovarian cancer. Additionally, we found that the five-year survival rate was higher in patients expressing low cyclin H than those expressing high cyclin H. Further, knockdown of cyclin H was achieved using an shRNA in HO8910 ovarian cancer cell line. Silencing cyclin H resulted in a G1/S cell cycle arrest in ovarian cancer cells suppressing its growth. The Ki67 expression was also decreased in cyclin H silenced ovarian cancer.ConclusionThese results suggest that high expression of cyclin H predicts the poor prognosis and promotes the growth of ovarian cancer by regulating the cell cycle.

Gonadotropin-Releasing Hormone Receptor-Targeted Near-Infrared Fluorescence Probe for Specific Recognition and Localization of Peritoneal Metastases of Ovarian Cancer.

Background: Peritoneal dissemination is common in advanced ovarian cancer. The completeness of cytoreduction is an independent prognostic factor. The intraoperative fluorescence imaging via tumor-specific near-infrared fluorophore might improve staging and surgical completeness. A promising target for ovarian cancer is the gonadotropin-releasing hormone receptor (GnRHR). This study aimed to develop a GnRHR-targeted near-infrared imaging probe for the detection of peritoneal metastases of ovarian cancer.Methods: Indocyanine green (ICG) was conjugated with GnRH antagonist peptide to develop an ovarian cancer-selective fluorescence probe GnRHa-ICG. GnRHR expression was detected in ovarian cancer tissues. The binding capacity of GnRHa-ICG and ICG was detected in both cancer cell lines and mouse models of peritoneal metastatic ovarian cancer using fluorescence microscopy, flow cytometry, and near-infrared fluorescence imaging.Results: Tissue microarray analysis revealed the overexpression of GnRHR in ovarian cancer. GnRH-ICG exhibited the binding capacity in a panel of cancer cell lines with different expression levels of GnRHR. In ovarian cancer mouse models, GnRHa-ICG signals were detected in peritoneal tumor lesions rather than normal peritoneal and intestines tissues. ICG showed intensive fluorescence signals in intestines. The tumor-to-muscle ratio and tumor-to-intestine ratio of GnRHa-ICG was 7.41 ± 2.82 and 4.37 ± 1.66, higher than that of ICG (4.60 ± 0.50 and 0.57 ± 0.06) at 2 h post administration. The fluorescence signal of peritoneal metastases peaked in intensity at 2 h and maintained for up to 48 h. ICG also showed a weak signal in the tumor lesions due to the enhanced permeability and retention effect, but the intensity decreased quickly within 48 h.Conclusions: The developed GnRHR-targeted imaging agent GnRHa-ICG could specifically detected peritoneal tumor lesions from normal peritoneal and intestines tissues because of the modification of GnRHa to ICG. The plateau period of GnRHa-ICG accumulation may be feasible for clinical applications in fluorescence-guided surgery. Our GnRHR imaging concept may be effective in other hormone-related tumors with upregulated GnRHR expression.

Poor perfusion of the microvasculature in peritoneal metastases of ovarian cancer

Most women with epithelial ovarian cancer (EOC) suffer from peritoneal carcinomatosis upon first clinical presentation. Extensive peritoneal carcinomatosis has a poor prognosis and its pathophysiology is not well understood. Although treatment with systemic intravenous chemotherapy is often initially successful, peritoneal recurrences occur regularly. We hypothesized that insufficient or poorly-perfused microvasculature may impair the therapeutic efficacy of systemic intravenous chemotherapy but may also limit expansive and invasive growth characteristic of peritoneal EOC metastases. In 23 patients with advanced EOC or suspicion thereof, we determined the angioarchitecture and perfusion of the microvasculature in peritoneum and in peritoneal metastases using incident dark field (IDF) imaging. Additionally, we performed immunohistochemical analysis and 3-dimensional (3D) whole tumor imaging using light sheet fluorescence microscopy of IDF-imaged tissue sites. In all metastases, microvasculature was present but the angioarchitecture was chaotic and the vessel density and perfusion of vessels was significantly lower than in unaffected peritoneum. Immunohistochemical analysis showed expression of vascular endothelial growth factor and hypoxia inducible factor 1α, and 3D imaging demonstrated vascular continuity between metastases and the vascular network of the peritoneum beneath the elastic lamina of the peritoneum. We conclude that perfusion of the microvasculature within metastases is limited, which may cause hypoxia, affect the behavior of EOC metastases on the peritoneum and limit the response of EOC metastases to systemic treatment.

Abstract TMIM-081: THE HYPOXIC TUMOR-MESOTHELIAL NICHE PROMOTES OVARIAN CANCER METASTASIS THROUGH COLLAGEN REMODELING

Abstract High grade serous ovarian cancer (HGSOC) is a leading cause of cancer related deaths among women. The primary cause of morbidity and mortality in HGSOC patients is metastasis to organs within the peritoneal cavity. Mesothelial cells line the surface of peritoneal organs and are a key stromal cell in HGSOC metastatic niche. However, the mechanisms by which mesothelial cells promote ovarian cancer peritoneal metastasis remain largely unknown. Here we demonstrate that tumor associated mesothelial cells promote tumor invasion by increasing collagen deposition and remodeling. Mechanistically, we demonstrate the tumor-mesothelial niche is hypoxic where both tumor cells and mesothelial cells express the hypoxia inducible factors HIF-1 and HIF-2 and their downstream target gene lysyl oxidase (LOX). LOX is an enzyme that crosslinks collagen fibrils to promote collagen remodeling. In tumor-mesothelial co-culture experiments, we demonstrate that hypoxia enhances extracellular fibrillar collagen deposition by mesothelial cells. Conditioned media from hypoxic tumor-mesothelial co-cultures promotes collagen remodeling and HGSOC tumor cell invasion. Genetic inactivation of either HIF-1 and HIF-2 or LOX reduces the hypoxic induction of collagen remodeling and tumor cell invasion. Importantly, pharmacologic inhibition of HIF-1 and HIF-2 with digoxin reduces the colonization of disseminated HGSOC cells to the omentum, the preferential migration site of peritoneal cancer metastasis. Moreover, pharmacologic inhibition of LOX with BAPN (beta-aminopropionitrile) is sufficient to inhibit metastatic tumor burden and collagen remodeling at metastatic sites in preclinical models of HGSOC metastasis. These data reveal a novel role for mesothelial cells in the production of type I collagen and collagen remodeling in the HGSOC metastatic microenvironment. Furthermore, these studies demonstrate a role for the HIF/LOX signaling axis in the HGSOC tumor-mesothelial niche that can be therapeutically targeted to inhibit collagen remodeling and ovarian cancer metastatic progression. Citation Format: Suchitra Natarajan, Katie Foreman, Michaela Soriano, Hussein Shehade, Daniel Fregoso, Joshua Eggold, Ninna S. Rosen, Sarah Heilshorn, Adam J. Krieg, Venkatesh Krishnan, Oliver Dorigo, Subarna Sinha, Katherine C. Fuh, Erinn B. Rankin. THE HYPOXIC TUMOR-MESOTHELIAL NICHE PROMOTES OVARIAN CANCER METASTASIS THROUGH COLLAGEN REMODELING [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr TMIM-081.

MCP-1/CCR-2 axis in adipocytes and cancer cell respectively facilitates ovarian cancer peritoneal metastasis.

Ovarian cancer selective metastasizes to the omentum contributing to the poor prognosis associated with ovarian cancer. However, the mechanism underlining this propensity and therapeutic approaches to counter this process has not been fully elucidated. Here, we show that MCP-1 produced by omental adipocytes binding to its cognate receptor CCR-2 on ovarian cancer cells facilitates migration and omental metastasis by activating the PI3K/AKT/mTOR pathway and its downstream effectors HIF-1α and VEGF-A in cell lines, xenografts, and transgenic murine models. MCP-1 antibody significantly decreased tumor burden and increased survival of mice in vivo. Interestingly, metformin decreased omental metastasis at least partially by inhibiting MCP-1 secretion from adipocytes independent of direct effects on cancer cells. Together this suggests a novel target of MCP-1/CCR-2 axis that could benefit ovarian cancer patients.

Tumor cell‑fibroblast heterotypic aggregates inmalignant ascites of patients with ovarian cancer.

Ascitic multicellular aggregates (MCAs) promote peritoneal metastasis of ovarian cancer. The aim of the present study was to elucidate the role of cancer-associated fibroblasts (CAFs) in MCA formation and metastasis in patients with high-grade serous ovarian cancer (HGSOC). Immunohistochemistry was used to identify the cell phenotypes and the presence of CAFs in ascitic MCAs. The role of CAFs in tumor-cell MCA formation was assessed by co-culture in suspension. Primary ascitic tumor cells and omental CAFs were used to generate ex vivo MCAs in hanging drops, and the invasiveness of MCAs was evaluated by mesothelial clearance and adhesion assays in vitro and in vivo. MCAs containing CAFs and tumor cells were identified in the ascitic fluid. CAFs facilitated tumor cell aggregation and compaction to form MCAs, and enhanced the mesothelial clearance and adhesion abilities of tumor-cell MCAs. These findings suggest that ascitic CAFs promote peritoneal metastasis by forming heterotypic aggregates with tumor cells, and that they may serve as potential targets for the treatment of HGSOC.

Correction: Targeting Leptin as a Therapeutic Strategy against Ovarian Cancer Peritoneal Metastasis.

The authors would like to correct Fig. 1, Fig. 3 and Fig. 5G, as errors were introduced in the preparation of these figures for publication. The authors declare that these corrections do not change the results or conclusions of this paper. We sincerely apologize for having this error in the article, and apologize for any inconvenience caused. The authors have provided corrected version of Fig. 1, Fig. 3 and Fig. 5G here.

Inhibitory effect of carbonyl reductase 1 against peritoneal progression of ovarian cancer: evaluation by ex vivo 3D-human peritoneal model.

The current authors previously reported that a carbonyl reductase 1 (CR1) DNA-dendrimer complex could potentially be used in gene therapy for peritoneal metastasis of ovarian cancer. The aims of the current study were to observe the cellular dynamics of peritoneal metastasis of epithelial ovarian cancer cells and to ascertain changes in the dynamics of ovarian cancer cells as a result of transfection of CR1 DNA. (1) Artificial human peritoneal tissue (AHPT) was seeded with serous ovarian cancer cells, and the process leading to development of peritoneal carcinomatosis was observed over time. (2) Peritoneal carcinomatosis was produced in mice and compared to a model using AHPT to determine the appropriateness of AHPT. (3) CR1 DNA was transfected into cancer cells seeded on AHPT, and the dynamics of cancer cells were observed over time. (1) Cancer cells perforated the mesothelium, leaving normal mesothelium intact. However, the cells proliferated between the layers of the mesothelium, forming a mass. After 24h, cancer cells had invaded the lymphatics, and after 48-72h cancer cells had invaded deep into the mesothelium, where they formed a mass. (2) Invasion of the peritoneum by cancer cells in a murine model of peritoneal carcinomatosis resembled that in a model using AHPT, and results substantiated the reproducibility of peritoneal carcinomatosis in AHPT. (3) Proliferation of cells transfected with CR1 DNA was significantly inhibited on AHPT, and necrosis was evident. Nevertheless, cancer cell invasion deep into the mesothelium was not inhibited. Use of a new tool, AHPT, in an in vitro model of peritoneal metastasis revealed that CR1 DNA inhibited cancer cell proliferation. CR1 DNA does not play a role in inhibiting invasion of the mesothelium during peritoneal metastasis, but it does affect cancer cell proliferation. Results suggested that CR1 DNA inhibits cancer cell proliferation via necrosis.

Photodynamic therapy of peritoneal metastases of ovarian cancer to improve microscopic cytoreduction and to enhance antitumoral immunity

Photodynamic therapy of peritoneal metastases of ovarian cancer to improve microscopic cytoreduction and to enhance antitumoral immunity

Heterotypic CAF-tumor spheroids promote early peritoneal metastatis of ovarian cancer.

High-grade serous ovarian cancer (HGSOC) is hallmarked by early onset of peritoneal dissemination, which distinguishes it from low-grade serous ovarian cancer (LGSOC). Here, we describe the aggressive nature of HGSOC ascitic tumor cells (ATCs) characterized by integrin α5high (ITGA5high) ATCs, which are prone to forming heterotypic spheroids with fibroblasts. We term these aggregates as metastatic units (MUs) in HGSOC for their advantageous metastatic capacity and active involvement in early peritoneal dissemination. Intriguingly, fibroblasts inside MUs support ATC survival and guide their peritoneal invasion before becoming essential components of the tumor stroma in newly formed metastases. Cancer-associated fibroblasts (CAFs) recruit ITGA5high ATCs to form MUs, which further sustain ATC ITGA5 expression by EGF secretion. Notably, LGSOC is largely devoid of CAFs and the resultant MUs, which might explain its metastatic delay. These findings identify a specialized MU architecture that amplifies the tumor-stroma interaction and promotes transcoelomic metastasis in HGSOC, providing the basis for stromal fibroblast-oriented interventions in hampering OC peritoneal propagation.

CDC25A Facilitates Chemo-resistance in Ovarian Cancer Multicellular Spheroids by Promoting E-cadherin Expression and Arresting Cell Cycles.

Peritoneal metastasis is the most common pathway for the spread of ovarian cancer and one of the major causes of cancer death. Ovarian cancer cells in ascites prefer to aggregate into the multicellular spheroids (MCS) with an inadequate response to chemotherapy. In this study, gene expression analysis implicated that ovarian cancer MCS had its unique expression pattern and the cell cycle-related pathways were prominently altered in MCS cells compared to the monolayer adherent cells. Flow cytometry and western blots confirmed the cell cycle stagnancy in MCS. Among the cell cycle-related proteins, we found that expression of CDC25A was upregulated in MCS and displayed a time-dependent decrease during the transition from MCS to monolayer adherent cells. Loss-of-function studies showed that CDC25A promoted cisplatin-resistance and paclitaxel-resistance and inhibited the drug-induced apoptosis in ovarian cancer MCS. Mechanically, CDC25A impeded cell cycle progression in MCS cells, enhanced their structure integrity, and maintained upregulation of E-cadherin in MCS cells. Accordingly, addition of NSC95397, a small molecular inhibitor of CDC25A, sensitized the ovarian cancer MCS to chemotherapeutic agents. This provides us a novel strategy for the treatment of ovarian cancer peritoneal metastasis and may help improve the overall survival of ovarian cancer patients.

Reversing platinum resistance in ovarian cancer multicellular spheroids by targeting Bcl-2.

PurposePeritoneal metastasis is the most common pathway for the spread of ovarian cancer. Ovarian cancer cells in ascites prefer to aggregate into the more chemoresistant multicellular spheroids (MCSs), leading to treatment failure and disease recurrence. We previously established a suspension MCS model of ovarian cancer cells in vitro and found that the MCS cells acquired drug resistance to cisplatin. In the present study, we aimed to uncover the underlying mechanism of the platinum resistance of MCS and the potential targets to reverse the drug resistance.Materials and methodsMCS models were established for the phenotypic studies, including proliferation, invasion, migration, drug resistance, apoptosis assays, and signaling pathway analysis. The key molecule, Bcl-2, was screened by profile analysis and validated by Western blotting. siRNA was used to verify the anti-cisplatin-induced apoptosis effect of Bcl-2. The Bcl-2 inhibitor, ABT-737, was used for improving the sensitivity of MCS to cisplatin. The 50% inhibitory concentrations (IC50) were measured by viability assays treated with different concentrations of cisplatin. Flow cytometry and Western blotting were used for quantification of drug-induced apoptosis.ResultsThe ovarian cancer MCS showed a proliferation-stagnant but invasive phenotype when resuspended. When treated with cisplatin, MCS cells showed much higher viability, with significantly fewer apoptotic cells than the adherent cells. Levels of Bcl-2 were upregulated in ovarian cancer ascitic cells and MCS cells. Bcl-2 knockdown by siRNA or blockage by ABT-737 enhanced the cisplatin-induced apoptosis and reduced the 50% inhibitory concentrations of cisplatin for MCS by 58.5% and 88.2%, respectively.ConclusionThe upregulated Bcl-2 contributes to cisplatin resistance in our MCS model and targeting it sensitizes the MCS to cisplatin treatment. This provides us a preliminary treatment method for ovarian cancer peritoneal metastasis.