Disaggregation and invasion of ovarian carcinoma ascites spheroids

A Peptide Derived from Nectin-4 Increases Cisplatin Cytotoxicity in Cell Lines and Cells from Ovarian Cancer Patients' Ascites

BACKGROUND/OBJECTIVES

New approaches to the treatment of women with ovarian cancer are desperately needed, since most women develop resistance to chemotherapy and the 5-year survival rate remains low. The hypothesis guiding this study was that the inhibition of cell adhesion could be used as a novel strategy to increase the chemosensitivity of ovarian cancer cells.

METHODS

The Nectin-4 peptide N4-P10 was used to inhibit the formation of cell-cell aggregates (spheroids) using cell lines and cells isolated from ovarian cancer patients' ascites. Cell lines were pre-treated with peptide N4-P10 or control scrambled peptides and monitored for spheroid formation with live-cell imaging by digital time-lapse photography. Cells were then tested for the cytotoxicity of the chemotherapeutic agent, cisplatin.

RESULTS

Peptide N4-P10 blocked aggregation in cell lines with different levels of Nectin-4 expression and different spheroid morphologies. The cytotoxicity of cisplatin increased in cells pre-treated with peptide N4-P10. Similarly, when single cells were isolated from the ascites of ovarian cancer patients, peptide N4-P10 blocked cell aggregation and increased the cytotoxicity of cisplatin.

CONCLUSIONS

These results suggest that targeting the cell-cell adhesive property of cancer cells could serve as a new approach to augment the cytotoxic effect of chemotherapy and potentially reduce disease recurrence in ovarian cancer patients.

Reversible downregulation of MYC in a spheroid model of metastatic epithelial ovarian cancer

Upon detachment from the primary tumour, epithelial ovarian cancer cells can form multicellular aggregates, also referred to as spheroids, that have the capacity to establish metastases at distant sites. These structures exhibit numerous adaptations that may facilitate metastatic transit and promote tumorigenic potential. One such adaptation is the acquisition of dormancy, characterized by decreased proliferation and molecular features of quiescence. One of the most frequently dysregulated genes in cancer is MYC, which encodes a transcription factor that promotes cell proliferation. In this study, we demonstrate that MYC protein abundance and associated gene expression is significantly decreased in EOC spheroids compared to adherent cells. This downregulation occurs rapidly upon cell detachment and is proteasome-dependent. Moreover, MYC protein abundance and associated gene expression is restored upon spheroid reattachment to an adherent culture surface. Overall, our findings suggest that suppression of MYC activity is a common feature of EOC spheroids and may contribute to the reversible acquisition of dormancy.

Beyond tumor‑associated macrophages involved in spheroid formation and dissemination: Novel insights for ovarian cancer therapy (Review)

Ovarian cancer (OC) is the most common and deadly malignant tumor of the female reproductive system. When OC cells detach from the primary tumor and enter the ascitic microenvironment, they are present as individual cells or multicellular spheroids in ascites. These spheroids, composed of cancer and non‑malignant cells, are metastatic units and play a crucial role in the progression of OC. However, little is known about the mechanism of spheroid formation and dissemination. Tumor‑associated macrophages (TAMs) in the center of spheroids are key in spheroid formation and metastasis and provide a potential target for OC therapy. The present review summarizes the key biological features of spheroids, focusing on the role of TAMs in spheroid formation, survival and peritoneal metastasis, and the strategies targeting TAMs to provide new insights in treating OC.

Ascites microenvironment conditions the peritoneal pre-metastatic niche to promote the implantation of ovarian tumor spheroids: Involvement of fibrinogen/fibrin and αV and α5β1 integrins

At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence especially because of the propensity of the OC cells to spread in the abdominal cavity leading to peritoneal metastasis. The influence of ascites on the development of pre-metastatic niches, and on the biological mechanisms leading to cancer cell colonization of the mesothelium, remains poorly understood. Here, we show that ascites weakens the mesothelium by affecting the morphology of mesothelial cells and by destabilizing their distribution in the cell cycle. Ascites also causes destabilization of the integrity of mesothelium by modifying the organization of cell junctions, but it does not affect the synthesis of N-cadherin and ZO-1 by mesothelial cells. Moreover, ascites induces disorganization of focal contacts and causes actin cytoskeletal reorganization potentially dependent on the activity of Rac1. Ascites allows the densification and reorganization of ECM proteins of the mesothelium, especially fibrinogen/fibrin, and indicates that it is a source of the fibrinogen and fibrin surrounding OC spheroids. The fibrin in ascites leads to the adhesion of OC spheroids to the mesothelium, and ascites promotes their disaggregation followed by the clearance of mesothelial cells. Both αV and α5β1 integrins are involved. In conclusion ascites and its fibrinogen/fibrin composition affects the integrity of the mesothelium and promotes the integrin-dependent implantation of OC spheroids in the mesothelium.

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.

Matriptase drives dissemination of ovarian cancer spheroids by a PAR-2/PI3K/Akt/MMP9 signaling axis

The transmembrane serine protease matriptase is a key regulator of both barrier-disruptive and protective epithelial cell-cell interactions. Elevated matriptase is a consistent feature of epithelial ovarian cancers (OvCa), where multicellular spheroids shed from the primary tumor into the peritoneal cavity are critical drivers of metastasis. Dynamic cell-to-cell adhesive contacts are required for spheroid formation and maintenance. Here, we show that overactive matriptase, reflected in an increased ratio of matriptase to its inhibitor hepatocyte growth factor activator inhibitor 1 (HAI-1), disrupts cell-cell contacts to produce loose prometastatic spheroids that display increased mesothelial cell adhesion and submesothelial invasion. We show that these activities are dependent on the matriptase activation of a protease-activated receptor-2 (PAR-2) signaling pathway involving PI3K/Akt and MMP9-induced disruption of cell-cell adhesion by the release of the soluble E-cadherin ectodomain. These data reveal a novel pathological connection between matriptase activation of PAR-2 and disruption of cell-cell adhesion, and support the clinical investigation of this signaling axis as a therapeutic strategy for aggressive metastatic OvCa.

Ascitic autotaxin as a potential prognostic, diagnostic, and therapeutic target for epithelial ovarian cancer

BACKGROUND

Malignant ascites contributes to the metastatic process by facilitating the multifocal dissemination of ovarian tumour cells onto the peritoneal surface. However, the prognostic and diagnostic relevance of ascitic fluid remains largely unknown. Herein, we investigated the potential clinical value and therapeutic utility of ascitic autotaxin (ATX) in epithelial ovarian cancer (EOC).

METHODS

ATX expression was assessed in clinical samples. Spheroid-forming assay, real-time PCR, western blot analysis, invadopodia assay, and adhesion assays were performed.

RESULTS

Ascitic ATX expression was highly elevated in patients with ovarian cancer compared to those with benign ascites and was associated with advanced stage, high grade, and a short disease-free period in patients with EOC. Combining the diagnostic ability of ascitic ATX and serum CA-125 levels significantly improved the area under the curve (AUC) value for EOC compared to serum CA125 level alone. This marker combination showed a large odds ratio for short disease-free period in high-risk EOC groups. Functional studies revealed that ascitic ATX was required for maintaining cancer stem cell-like characteristics and invadopodia formation.

CONCLUSION

Ascitic ATX levels may serve as a useful prognostic indicator for predicting aggressive behaviour in EOC. ATX-linked invadopodia are a potential target to prevent peritoneal dissemination in ovarian cancer.

Omentum-on-a-chip: A multicellular, vascularized microfluidic model of the human peritoneum for the study of ovarian cancer metastases

Epithelial ovarian cancer has the highest mortality rate of any gynecologic malignancy and most frequently metastasizes to the peritoneal cavity. Intraperitoneal metastases are highly associated with ascites, the pathologic accumulation of peritoneal fluid due to impaired drainage, increased peritoneal permeability, and tumor and stromal cytokine secretion. However, the relationship between ascites, vascular and mesothelial permeability, and ovarian cancer intraperitoneal metastases remains poorly understood. In this study, a vascularized in vitro model of the human peritoneal omentum and ovarian tumor microenvironment (TME) was employed to study stromal cell effects on tumor cell (TC) attachment and growth, as well as TC effects on vascular and mesothelial permeability in models of both early- and late-stage metastases. Control over the number of TCs seeded in the vascularized peritoneum revealed a critical cell density requirement for tumor growth, which was further enhanced by stromal adipocytes and endothelial cells found in the peritoneal omentum. This tumor growth resulted in both a physically-mediated decrease and cytokine-mediated increase in microvascular permeability, emphasizing the important and potentially opposing roles of tumor cells in ascites formation. This system provides a robust platform to elucidate TC-stromal cell interactions during intraperitoneal metastasis of ovarian cancer and presents the first in vitro vascularized model of the human peritoneum and ovarian cancer TME.

Using GPCRs as Molecular Beacons to Target Ovarian Cancer with Nanomedicines

The five-year survival rate for women with ovarian cancer is very poor despite radical cytoreductive surgery and chemotherapy. Although most patients initially respond to platinum-based chemotherapy, the majority experience recurrence and ultimately develop chemoresistance, resulting in fatal outcomes. The current administration of cytotoxic compounds is hampered by dose-limiting severe adverse effects. There is an unmet clinical need for targeted drug delivery systems that transport chemotherapeutics selectively to tumor cells while minimizing off-target toxicity. G protein-coupled receptors (GPCRs) are the largest family of membrane receptors, and many are overexpressed in solid tumors, including ovarian cancer. This review summarizes the progress in engineered nanoparticle research for drug delivery for ovarian cancer and discusses the potential use of GPCRs as molecular entry points to deliver anti-cancer compounds into ovarian cancer cells. A newly emerging treatment paradigm could be the personalized design of nanomedicines on a case-by-case basis.

Hsa_circ_0000497 and hsa_circ_0000918 contributed to peritoneal metastasis of ovarian cancer via ascites

PURPOSE

As a common complication of epithelial ovarian cancer (EOC), malignant ascites contributes to the peritoneal metastasis of EOC. CircRNAs play essential roles in tumor metastasis. However, no circRNAs have been reported to be involved in EOC peritoneal metastasis via ascites.

METHODS

Total of 22 samples from 9 EOC patients containing primary lesions (T), tumor cells from ascites (ASC), and metastatic lesions (M) were included for RNA sequencing to identify differentially expressed circRNAs and mRNAs among different tumors. Bioinformatic analyses, including single-sample Gene Set Enrichment Analysis and soft cluster analysis, were performed to find circRNAs potentially correlated with ascitic metastasis. Wound healing and transwell analysis were performed to evaluate tumor cells metastasis in vitro. Quantitative real-time PCR and western-blot were used for gene expression evaluation.

RESULTS

According to transcriptomic analysis, ASC showed mesenchymal phenotype while T and M showed epithelial phenotype. 10 circRNAs were differentially expressed among ASC, T, and M. Among them, hsa_circ_0000497 and hsa_circ_0000918 were significantly up-regulated in ASC. Functional analysis showed that both hsa_circ_0000497 and hsa_circ_0000918 promoted metastasis of EOC via epithelial-mesenchymal transition (EMT) in vitro. The regulatory network construction identified 8 miRNAs and 19 mRNAs, and 7 miRNAs and 17 mRNAs as potential downstream target genes of hsa_circ_0000497 and hsa_circ_0000918, respectively, which may play pivotal roles in EOC ascitic metastasis.

CONCLUSIONS

circRNAs (hsa_circ_0000497 and hsa_circ_0000918) contribute to metastasis of EOC via ascites by regulating EMT. These circRNAs may serve as novel potential therapeutic targets or prognostic biomarkers for EOC peritoneal metastasis.

Ovarian Cancer Ascites Inhibits Transcriptional Activation of NK Cells Partly through CA125

Malignant ascites is a common clinical problem in ovarian cancer. NK cells are present in the ascites, but their antitumor activity is inhibited. The underlying mechanisms of the inhibition have yet to be fully elucidated. Using an Fcγ receptor-mediated NK cell activation assay, we show that ascites from ovarian cancer patients potently inhibits NK cell activation. Part of the inhibitory activity is mediated by CA125, a mucin 16 fragment shed from ovarian cancer tumors. Moreover, transcriptional analyses by RNA sequencing reveal upregulation of genes involved in multiple metabolic pathways but downregulation of genes involved in cytotoxicity and signaling pathways in NK cells purified from ovarian cancer patient ascites. Transcription of genes involved in cytotoxicity pathways are also downregulated in NK cells from healthy donors after in vitro treatment with ascites or with a CA125-enriched protein fraction. These results show that ascites and CA125 inhibit antitumor activity of NK cells at transcriptional levels by suppressing expression of genes involved in NK cell activation and cytotoxicity. Our findings shed light on the molecular mechanisms by which ascites inhibits the activity of NK cells and suggest possible approaches to reactivate NK cells for ovarian cancer immunotherapy.

Targeting LRRC15 Inhibits Metastatic Dissemination of Ovarian Cancer

Dissemination of ovarian cancer cells can lead to inoperable metastatic lesions in the bowel and omentum that cause patient death. Here we show that LRRC15, a type-I 15-leucine-rich repeat-containing membrane protein, highly overexpressed in ovarian cancer bowel metastases compared with matched primary tumors and acts as a potent promoter of omental metastasis. Complementary models of ovarian cancer demonstrated that LRRC15 expression leads to inhibition of anoikis-induced cell death and promotes adhesion and invasion through matrices that mimic omentum. Mechanistically, LRRC15 interacted with β1-integrin to stimulate activation of focal adhesion kinase (FAK) signaling. As a therapeutic proof of concept, targeting LRRC15 with the specific antibody-drug conjugate ABBV-085 in both early and late metastatic ovarian cancer cell line xenograft models prevented metastatic dissemination, and these results were corroborated in metastatic patient-derived ovarian cancer xenograft models. Furthermore, treatment of 3D-spheroid cultures of LRRC15-positive patient-derived ascites with ABBV-085 reduced cell viability. Overall, these data uncover a role for LRRC15 in promoting ovarian cancer metastasis and suggest a novel and promising therapy to target ovarian cancer metastases.

Significance: This study identifies that LRRC15 activates β1-integrin/FAK signaling to promote ovarian cancer metastasis and shows that the LRRC15-targeted antibody-drug conjugate ABBV-085 suppresses ovarian cancer metastasis in preclinical models.

A phenotype-structured model to reproduce the avascular growth of a tumor and its interaction with the surrounding environment

We here propose a one-dimensional spatially explicit phenotype-structured model to analyze selected aspects of avascular tumor progression. In particular, our approach distinguishes viable and necrotic cell fractions. The metabolically active part of the disease is, in turn, differentiated according to a continuous trait, that identifies cell variants with different degrees of motility and proliferation potential. A parabolic partial differential equation (PDE) then governs the spatio-temporal evolution of the phenotypic distribution of active cells within the host tissue. In this respect, active tumor agents are allowed to duplicate, move upon haptotactic and pressure stimuli, and eventually undergo necrosis. The mutual influence between the emerging malignancy and its environment (in terms of molecular landscape) is implemented by coupling the evolution law of the viable tumor mass with a parabolic PDE for oxygen kinetics and a differential equation that accounts for local consumption of extracellular matrix (ECM) elements. The resulting numerical realizations reproduce tumor growth and invasion in a number scenarios that differ for cell properties (i.e., individual migratory behavior, duplication and mutation potential) and environmental conditions (i.e., level of tissue oxygenation and homogeneity in the initial matrix profile). In particular, our simulations show that, in all cases, more mobile cell variants occupy the front edge of the tumor, whereas more proliferative clones are selected at the more internal regions. A necrotic core constantly occupies the bulk of the mass due to nutrient deprivation. This work may eventually suggest some biomedical strategies to partially reduce tumor aggressiveness, i.e., to enhance necrosis of malignant tissue and to promote the presence of more proliferative cell phenotypes over more invasive ones.

Extracellular matrix mediates moruloid-blastuloid morphodynamics in malignant ovarian spheroids

Ovarian cancer metastasizes into peritoneum through dissemination of transformed epithelia as multicellular spheroids. Harvested from the malignant ascites of patients, spheroids exhibit startling features of organization typical to homeostatic glandular tissues: lumen surrounded by smoothly contoured and adhered epithelia. Herein, we demonstrate that cells of specific ovarian cancer lines in suspension, aggregate into dysmorphic solid "moruloid" clusters that permit intercellular movement, cell penetration, and interspheroidal coalescence. Moruloid clusters subsequently mature into "blastuloid" spheroids with smooth contours, a temporally dynamic lumen and immotile cells. Blastuloid spheroids neither coalesce nor allow cell penetration. Ultrastructural examination reveals a basement membrane-like extracellular matrix coat on the surface of blastuloid, but not moruloid, spheroids. Quantitative proteomics reveals down-regulation in ECM protein Fibronectin-1 associated with the moruloid-blastuloid transition; immunocytochemistry also confirms the relocalization of basement membrane ECM proteins: collagen IV and laminin to the surface of blastuloid spheroids. Fibronectin depletion accelerates, and enzymatic basement membrane debridement impairs, lumen formation, respectively. The regulation by ECM dynamics of the morphogenesis of cancer spheroids potentially influences the progression of the disease.

Loss of Krüppel-like factor 9 facilitates stemness in ovarian cancer ascites-derived multicellular spheroids via Notch1/slug signaling

The ascites that develops in advanced OC, both at diagnosis and upon recurrence, is a rich source of multicellular spheroids/aggregates (MCSs/MCAs), which are the major seeds of tumor cell dissemination within the abdominal cavity. However, the molecular mechanism by which specific ascites-derived tumor cells survive and metastasize remains largely unknown. In this study, we elucidated cancer stem cell (CSC) properties of ascites-derived MCSs, concomitant with enhanced malignancy, induced EMT, and low KLF9 (Krüppel-like factor 9) expression, compared with PTCs. KLF9 was also downregulated in OC cell line-derived spheroids and the CD117⁺ CD44⁺ subpopulation in MCSs. Functional experiments demonstrated that KLF9 negatively modulated stem-like properties in OC cells. Mechanistic studies revealed that KLF9 reduced the transcriptional expression of Notch1 by directly binding to the Notch1 promoter, thereby inhibiting the function of slug in a CSL-dependent manner. Clinically, expression of KLF9 was associated with histological grade and loss of KLF9 predicts poor prognosis in OC.

Sonosensitizer-Functionalized Graphene Nanoribbons for Adhesion Blocking and Sonodynamic Ablation of Ovarian Cancer Spheroids

Advanced stage ovarian cancer is challenging to treat due to widespread seeding of tumor spheroids throughout the mesothelial lining of the peritoneal cavity. In this work, a therapeutic strategy using graphene nanoribbons (GNR) functionalized with 4-arm polyethylene glycol (PEG) and chlorin e6 (Ce6), a sonosensitizer, to target metastatic ovarian cancer spheroids is reported. GNR-PEG-Ce6 adsorbs onto the spheroids and disrupts their adhesion to extracellular matrix proteins or LP-9 mesothelial cells. Furthermore, for spheroids that do adhere, GNR-PEG-Ce6 delays spheroid disaggregation and spreading as well as mesothelial clearance, key metastatic processes following adhesion. Owing to the sonodynamic effects of Ce6 and its localized delivery via the biomaterial, GNR-PEG-Ce6 can kill ovarian cancer spheroids adhered to LP-9 cell monolayers when combined with mild ultrasound irradiation. The interaction with GNR-PEG-Ce6 also loosens cell-cell adhesions within the spheroids, rendering them more susceptible to treatment with the chemotherapeutic agents cisplatin and paclitaxel, which typically have difficulty in penetrating ovarian cancer spheroids. Thus, this material can facilitate effective chemotherapeutic and sonodynamic combination therapies. Finally, the adhesion inhibiting and sonodynamic effects of GNR-PEG-Ce6 are also validated with tumor spheroids derived from the ascites fluid of ovarian cancer patients, providing evidence of the translational potential of this biomaterial approach.

Progesterone Receptors Promote Quiescence and Ovarian Cancer Cell Phenotypes via DREAM in p53-Mutant Fallopian Tube Models

CONTEXT

The ability of ovarian steroids to modify ovarian cancer (OC) risk remains controversial. Progesterone is considered to be protective; recent studies indicate no effect or enhanced OC risk. Knowledge of progesterone receptor (PR) signaling during altered physiology that typifies OC development is limited.

OBJECTIVE

This study defines PR-driven oncogenic signaling mechanisms in p53-mutant human fallopian tube epithelia (hFTE), a precursor of the most aggressive OC subtype.

METHODS

PR expression in clinical samples of serous tubal intraepithelial carcinoma (STIC) lesions and high-grade serous OC (HGSC) tumors was analyzed. Novel PR-A and PR-B isoform-expressing hFTE models were characterized for gene expression and cell cycle progression, emboli formation, and invasion. PR regulation of the DREAM quiescence complex and DYRK1 kinases was established.

RESULTS

STICs and HGSC express abundant activated phospho-PR. Progestin promoted reversible hFTE cell cycle arrest, spheroid formation, and invasion. RNAseq/biochemical studies revealed potent ligand-independent/-dependent PR actions, progestin-induced regulation of the DREAM quiescence complex, and cell cycle target genes through enhanced complex formation and chromatin recruitment. Disruption of DREAM/DYRK1s by pharmacological inhibition, HPV E6/E7 expression, or DYRK1A/B depletion blocked progestin-induced cell arrest and attenuated PR-driven gene expression and associated OC phenotypes.

CONCLUSION

Activated PRs support quiescence and pro-survival/pro-dissemination cell behaviors that may contribute to early HGSC progression. Our data support an alternative perspective on the tenet that progesterone always confers protection against OC. STICs can reside undetected for decades prior to invasive disease; our studies reveal clinical opportunities to prevent the ultimate development of HGSC by targeting PRs, DREAM, and/or DYRKs.

Group III phospholipase A2 downregulation attenuated survival and metastasis in ovarian cancer and promotes chemo-sensitization

Background

Aberrant lipogenicity and deregulated autophagy are common in most advanced human cancer and therapeutic strategies to exploit these pathways are currently under consideration. Group III Phospholipase A2 (sPLA2-III/PLA2G3), an atypical secretory PLA2, is recognized as a regulator of lipid metabolism associated with oncogenesis. Though recent studies reveal that high PLA2G3 expression significantly correlates with poor prognosis in several cancers, however, role of PLA2G3 in ovarian cancer (OC) pathogenesis is still undetermined.

Methods

CRISPR-Cas9 and shRNA mediated knockout and knockdown of PLA2G3 in OC cells were used to evaluate lipid droplet (LD) biogenesis by confocal and Transmission electron microscopy analysis, and the cell viability and sensitization of the cells to platinum-mediated cytotoxicity by MTT assay. Regulation of primary ciliation by PLA2G3 downregulation both genetically and by metabolic inhibitor PFK-158 induced autophagy was assessed by immunofluorescence-based confocal analysis and immunoblot. Transient transfection with GFP-RFP-LC3B and confocal analysis was used to assess the autophagic flux in OC cells. PLA2G3 knockout OVCAR5 xenograft in combination with carboplatin on tumor growth and metastasis was assessed in vivo. Efficacy of PFK158 alone and with platinum drugs was determined in patient-derived primary ascites cultures expressing PLA2G3 by MTT assay and immunoblot analysis.

Results

Downregulation of PLA2G3 in OVCAR8 and 5 cells inhibited LD biogenesis, decreased growth and sensitized cells to platinum drug mediated cytotoxicity in vitro and in in vivo OVCAR5 xenograft. PLA2G3 knockdown in HeyA8MDR-resistant cells showed sensitivity to carboplatin treatment. We found that both PFK158 inhibitor-mediated and genetic downregulation of PLA2G3 resulted in increased number of percent ciliated cells and inhibited cancer progression. Mechanistically, we found that PFK158-induced autophagy targeted PLA2G3 to restore primary cilia in OC cells. Of clinical relevance, PFK158 also induces percent ciliated cells in human-derived primary ascites cells and reduces cell viability with sensitization to chemotherapy.

Conclusions

Taken together, our study for the first time emphasizes the role of PLA2G3 in regulating the OC metastasis. This study further suggests the therapeutic potential of targeting phospholipases and/or restoration of PC for future OC treatment and the critical role of PLA2G3 in regulating ciliary function by coordinating interface between lipogenesis and metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01985-9.

Inhibiting the Growth of 3D Brain Cancer Models with Bio-Coronated Liposomal Temozolomide

Nanoparticles (NPs) have emerged as an effective means to deliver anticancer drugs into the brain. Among various forms of NPs, liposomal temozolomide (TMZ) is the drug-of-choice for the treatment and management of brain tumours, but its therapeutic benefit is suboptimal. Although many possible reasons may account for the compromised therapeutic efficacy, the inefficient tumour penetration of liposomal TMZ can be a vital obstacle. Recently, the protein corona, i.e., the layer of plasma proteins that surround NPs after exposure to human plasma, has emerged as an endogenous trigger that mostly controls their anticancer efficacy. Exposition of particular biomolecules from the corona referred to as protein corona fingerprints (PCFs) may facilitate interactions with specific receptors of target cells, thus, promoting efficient internalization. In this work, we have synthesized a set of four TMZ-encapsulating nanomedicines made of four cationic liposome (CL) formulations with systematic changes in lipid composition and physical−chemical properties. We have demonstrated that precoating liposomal TMZ with a protein corona made of human plasma proteins can increase drug penetration in a 3D brain cancer model derived from U87 human glioblastoma multiforme cell line leading to marked inhibition of tumour growth. On the other side, by fine-tuning corona composition we have also provided experimental evidence of a non-unique effect of the corona on the tumour growth for all the complexes investigated, thus, clarifying that certain PCFs (i.e., APO-B and APO-E) enable favoured interactions with specific receptors of brain cancer cells. Reported results open new perspectives into the development of corona-coated liposomal drugs with enhanced tumour penetration and antitumour efficacy.

A biomimetic model of 3D fluid extracellular macromolecular crowding microenvironment fine-tunes ovarian cancer cells dissemination phenotype

An early fundamental step in ovarian cancer progression is the dissemination of cancer cells through liquid environments, one of them being cancer ascites accumulated in the peritoneal cavity. These biological fluids are highly crowded with a high total macromolecule concentration. This biophysical property of fluids is widely used in tissue engineering for a few decades now, yet is largely underrated in cancer biomimetic models. To unravel the role of fluids extracellular macromolecular crowding (MMC), we exposed ovarian cancer cells (OCC) to high molecular weight inert polymer solutions. High macromolecular composition of extracellular liquid presented a differential effect: i) it impeded non-adherent OCC aggregation in suspension and, decreased their adhesion; ii) it promoted adherent OCC migration by decreasing extracellular matrix deposition. Besides, there seemed to be a direct link between the extracellular MMC and intracellular processes, especially the actin cytoskeleton organization and the nucleus morphology. In conclusion, extracellular fluid MMC orients OCC dissemination phenotype. Integrating MMC seems crucial to produce more relevant mimetic 3D in vitro fluid models to study ovarian dissemination but also to screen drugs.

Constitutive activation of integrin αvβ3 contributes to anoikis resistance of ovarian cancer cells

Epithelial ovarian cancer involves the shedding of single tumor cells or spheroids from the primary tumor into ascites, followed by their survival, and transit to the sites of metastatic colonization within the peritoneal cavity. During their flotation, anchorage-dependent epithelial-type tumor cells gain anoikis resistance, implicating integrins, including αvß3. In this study, we explored anoikis escape, cisplatin resistance, and prosurvival signaling as a function of the αvß3 transmembrane conformational activation state in cells suspended in ascites. A high-affinity and constitutively signaling-competent αvß3 variant, which harbored unclasped transmembrane domains, was found to confer delayed anoikis onset, enhanced cisplatin resistance, and reduced cell proliferation in ascites or 3D-hydrogels, involving p27^kip upregulation. Moreover, it promoted EGF-R expression and activation, prosurvival signaling, implicating FAK, src, and PKB/Akt. This led to the induction of the anti-apoptotic factors Bcl-2 and survivin suppressing caspase activation, compared to a signaling-incapable αvß3 variant displaying firmly associated transmembrane domains. Dissecting the mechanistic players for αvß3-dependent survival and peritoneal metastasis of ascitic ovarian cancer spheroids is of paramount importance to target their anchorage independence by reversing anoikis resistance and blocking αvß3-triggered prosurvival signaling.

The effects of size and shape of the ovarian cancer spheroids on the drug resistance and migration

BACKGROUND

High fatality in ovarian cancer is attributed to metastasis, propagated by the release of multi-cellular aggregates/spheroids into the peritoneal cavity and their subsequent mesothelial invasion of peritoneal organs. Spheroids are therefore a common and clinically relevant in vitro model for ovarian cancer research. Spheroids in patients vary significantly in size and shape and display enhanced resistance to anti-cancer drugs compared to monolayers. However, there is no consensus on how spheroid size and shape affect drug resistance. Moreover, existing data regarding the influence of epithelial-to-mesenchymal transition (EMT) profile on spheroid shape and migration is inconclusive.

METHODS

We formed spheroids with OVCAR-3 and OVCAR-8 cells, chosen for their established genetic similarity to the patient tumor samples. We monitored their morphology using confocal microscope with dipping objective and fluorescent microscope. We characterized important EMT biomarkers; E-cadherin, Vimentin and Slug through western blotting in monolayers and spheroids. We treated these spheroids with Taxol and Cisplatin and investigated their migratory profile based on their morphology.

RESULTS

We report two distinct multicellular structures: loose aggregates (OVCAR-3) and compact spheroids (OVCAR-8). We attribute these different morphologies to the expression of the EMT biomarkers, and their changes upon spheroid formation. Importantly, we did not observe a difference in resistance to the anti-cancer drugs as a function of spheroid size and shape. However, migration capacity of compact spheroid (OVCAR-8) was 15-fold higher compared to that of loose aggregates (OVCAR-3).

CONCLUSIONS

These results highlight the importance of spheroid size and shape on anti-cancer drug resistance and migration profiles. The results of this study can, therefore, help to elucidate general rules for ovarian cancer studies based on 3D samples.

Spheroid-Based Approach to Assess the Tissue Relevance of Analysis of Dispersed-Settled Tissue Cells by Cytometry of the Reaction Rate Constant

Cytometry of Reaction Rate Constant (CRRC) uses time-lapse fluorescence microscopy to measure a rate constant of a catalytic reaction in individual cells and, thus, facilitate accurate size determination for cell subpopulations with distinct efficiencies of this reaction. Reliable CRRC requires uniform exposure of cells to the reaction substrate followed by their uniform imaging, which in turn, requires that a tissue sample be disintegrated into a suspension of dispersed cells, and these cells settle on the support surface before being analyzed by CRRC. We call such cells "dispersed-settled" to distinguish them from cells cultured as a monolayer. Studies of the dispersed-settled cells can be tissue-relevant only if the cells maintain their 3D tissue state during the multi-hour CRRC procedure. Here, we propose an approach for assessing tissue relevance of the CRRC-based analysis of the dispersed-settled cells. Our approach utilizes cultured multicellular spheroids as a 3D cell model and cultured cell monolayers as a 2D cell model. The CRRC results of the dispersed-settled cells derived from spheroids are compared to those of spheroids and monolayers in order to find if the dispersed-settled cells are representative of the spheroids. To demonstrate its practical use, we applied this approach to a cellular reaction of multidrug resistance (MDR) transport, which was followed by extrusion of a fluorescent substrate from the cells. The approach proved to be reliable and revealed long-term maintenance of MDR transport in the dispersed-settled cells obtained from cultured ovarian cancer spheroids. Accordingly, CRRC can be used to determine accurately the size of a cell subpopulation with an elevated level of MDR transport in tumor samples, which makes CRRC a suitable method for the development of MDR-based predictors of chemoresistance. The proposed spheroid-based approach for validation of CRRC is applicable to other types of cellular reactions and, thus, will be an indispensable tool for transforming CRRC from an experimental technique into a practical analytical tool.

Single-cell EMT-related transcriptional analysis revealed intra-cluster heterogeneity of tumor cell clusters in epithelial ovarian cancer ascites

Malignant ascites of epithelial ovarian cancer is a metastatic tumor microenvironment in which large amounts of disseminated single cells (DSCs) and disseminated tumor cell clusters (DTCCs) are commonly observed. The tumor cell clusters are known to be more aggressive than individual tumor cells in cancer metastasis; however, little is known about the mechanism. Applying single-cell epithelial-to-mesenchymal transition (EMT)-related transcriptional analysis in 120 DSCs and 195 intra-cluster cells from 27 DTCCs, we demonstrated that DTCCs were heterogeneous cellular units comprised of epithelial tumor cells, leukocytes, and cancer-associated fibroblasts (CAFs). Through the analysis of intra-DTCC heterogeneity, we identified that CAFs induced EMT of tumor cells via TGFβ signaling within the DTCC microenvironment. The activation of EMT program, in particular the upregulation of ZEB2, enabled the acquisition of additional chemoresistance and metastasis abilities of the intra-DTCC tumor cells, which resulted in the aggressiveness of DTCCs.

The Capacity of High-Grade Serous Ovarian Cancer Cells to Form Multicellular Structures Spontaneously along Disease Progression Correlates with Their Orthotopic Tumorigenicity in Immunosuppressed Mice

Many studies have examined the biology, genetics, and chemotherapeutic response of ovarian cancer's solid component; its liquid facet, however, remains critically underinvestigated. Floating within peritoneal effusions known as ascites, ovarian cancer cells form multicellular structures, creating a cancer niche in suspension. This study explores the pathobiology of spontaneously formed, multicellular, ovarian cancer structures derived from serous ovarian cancer cells isolated along disease evolution. It also tests their capacity to cause peritoneal disease in immunosuppressed mice. Results stem from an analysis of cell lines representing the most frequently diagnosed ovarian cancer histotype (high-grade serous ovarian cancer), derived from ascites of the same patient at distinct stages of disease progression. When cultured under adherent conditions, in addition to forming cellular monolayers, the cultures developed areas in which the cells grew upwards, forming densely packed multilayers that ultimately detached from the bottom of the plates and lived as free-floating, multicellular structures. The capacity to form foci and to develop multicellular structures was proportional to disease progression at the time of ascites extraction. Self-assembled in culture, these structures varied in size, were either compact or hollow, irregular, or spheroidal, and exhibited replicative capacity and an epithelial nature. Furthermore, they fully recreated ovarian cancer disease in immunosuppressed mice: accumulation of malignant ascites and pleural effusions; formation of discrete, solid, macroscopic, peritoneal tumors; and microscopic growths in abdominal organs. They also reproduced the histopathological features characteristic of high-grade serous ovarian cancer when diagnosed in patients. The following results encourage the development of therapeutic interventions to interrupt the formation and/or survival of multicellular structures that constitute a floating niche in the peritoneal fluid, which in turn halts disease progression and prevents recurrence.

Characterization of ascites-derived aldehyde dehydrogenase-positive ovarian cancer stem cells isolated from Leghorn chickens

Leghorn chickens are used as a preclinical model of ovarian cancer as they develop epithelial ovarian adenocarcinoma spontaneously at a very high frequency. Ovarian cancer is the most lethal disease among all gynecological malignancies in women. A small proportion of ovarian cancer stem cells are responsible for drug resistance and relapse of ovarian cancer. The objectives of this study are to isolate ovarian cancer stem cells from ascites of Leghorn chickens that spontaneously developed ovarian cancer and to determine their invasiveness, spheroid formation in three-dimensional culture devoid of extracellular matrix over several months. Ovarian cancer cells obtained from ascites were subjected to ALDEFLOUR assay that measures aldehyde dehydrogenase (ALDH) activity to separate ALDH1⁺ and ALDH1^- cells by fluorescence-activated cell sorting. The cells were cultured using serum-free media for up to 6 mo in ultra-low attachment plates. Invasiveness of ALDH1⁺ and ALDH1^- cells was determined by Matrigel invasion assay. Cellular uptake of acetylated low-density lipoprotein was evaluated. A small proportion (<4.75%) of ovarian cancer cells isolated from ascites were found to be ALDH1⁺ cells. ALDH1⁺ cells formed a greater number of spheroids and were also highly invasive in extracellular matrix compared to ALDH1^- cells. Several spheroids developed 0.1- to 1-mm-long capillary-like tubules connecting other spheroids, thus forming a complex network that underwent remodeling over several months. Cells in the spheroids incorporated acetylated low-density lipoprotein suggestive of scavenger receptor activity. In summary, ALDH1⁺ ovarian cancer stem cells isolated from ascites of chickens appear to be invasive and form spheroids with complex networks of tubules reminiscent of vascular mimicry. Understanding the structure and function of spheroids and tubular network would provide valuable insight into the biology of ovarian cancer and improve poultry health.

Fibrin Deposit on the Peritoneal Surface Serves as a Niche for Cancer Expansion in Carcinomatosis Patients

Peritoneal metastasis (PM) is a very serious complication of gastrointestinal and gynecological malignancies which is poorly documented. Modified mesothelial cell layer and their microenvironments can favor fibrin deposition for cancer cell adhesion. Scanning and transmission electron microscopy of peritoneal surface and cancer cell clusters from cancer patients was done. Ascites and its impact on mesothelial cells were assessed by cytokine array. Neprilysin, matrix metalloprotease, epithelial mesenchymal transition (EMT) related molecules (E-cadherin, Snail, Slug, Twist, Vimentin and Fibronectin), tissues factor (TF), endothelial protein C receptors (EPCR) were quantified by q-PCR. Fibrin in the simples were stained using anti fibrin F1E1 antibody. Migration ability was assessed by scratch assay. Cell viability and neprilysin activity were analyzed by bioluminescence. Cancer cells-fibrin interaction was investigated by scanning electron microscopy (SEM) and microcinematography (MCG). Mesothelial cells change their morphology after incubation with carcinomatosis peritoneal fluids in vitro. EMT associated with upregulation of neprilysin, matrix metalloproteinase-2, tissue factor and cytokines secretions such as interleukin-6, and 8, hepatocyte growth factor and granulocyte chemotactic protein-2 mRNA and protein were observed. EPCR expression as a natural anticoagulant was decreased. In parallel, carcinomatosis cell clusters extracted from peritoneal fluids were found to be associated with fibrin. Kinetic analysis of cancer cell-fibrin interaction in vitro studied by MCG showed that fiber filaments generated from clots inhibited cancer cell adhesion on fibrin clots. These results indicated that fibrin deposit on the peritoneal surface serve as niches for cancer expansion in carcinomatosis patients.

SMYD3 promotes implant metastasis of ovarian cancer via H3K4 trimethylation of integrin promoters

Detachment of cancer cells from the primary tumor and formation of spheroids in ascites is required for implantation metastasis in epithelial ovarian cancer (EOC), but the underlying mechanism of this process has not been thoroughly elucidated. To mimic this process, ovarian cancer cells were grown in 3D and 2D culture. Hey and OVCA433 spheroids exhibited decreased cell proliferation and enhanced adhesion and invasion. SMYD3 expression was elevated in ovarian carcinoma spheroids in association with increased H3K4 methylation. Depletion of SMYD3 by transient siRNA, stable shRNA knockdown and the SMYD3 inhibitor BCI-121 all decreased spheroid invasion and adhesion. Gene expression arrays revealed downregulation of integrin family members. Inhibition assays confirmed that invasion and adhesion of spheroids are mediated by ITGB6 and ITGAM. SMYD3-deficient cells regained the ability to invade and adhere after forced overexpression of SMYD3, ITGB6 and ITGAM. However, this biological ability was not restored by forced overexpression of SMYD3 in ITGB6- and/or ITGAM-deficient cancer cells. SMYD3 and H3K4me3 binding at the ITGB6 and ITGAM promoters was increased in spheroids compared to that in monolayer cells, and the binding was decreased when SMYD3 expression was inhibited, consistent with the expression changes in integrins. SMYD3 expression and integrin-mediated adhesion were also activated in an intraperitoneal xenograft model and in EOC patient spheroids. In vivo, SMYD3 knockdown inhibited tumor metastasis and reduced ascites volume in both the intraperitoneal xenograft model and a PDX model. Overall, our results suggest that the SMYD3-H3K4me3-integrin pathway plays a crucial role in ovarian cancer metastasis to the peritoneal surface.

Tumor-Associated Macrophages (TAMs): A Critical Activator In Ovarian Cancer Metastasis

Tumor-associated macrophages (TAMs) that appear in every stage of cancer progression are usually tumor-promoting cells and are present abundantly in the tumor-associated microenvironment. In ovarian cancer, the overall and intratumoral M1/M2 ratio is a relatively efficient TAM parameter for predicting the prognosis of patients, especially for serous tissue type cancer. TAMs exhibit immunological checkpoint modulators, such as the B7 family and programmed death-ligand 1 (PD-L1), and play a key role in the development, metastasis and invasion of ovarian cancer, but the underlying mechanism is barely understood. Ovarian cancer is a severe gynecological malignancy with high mortality. Ovarian cancer-associated death can primarily be attributed to cancer metastasis. The majority of patients are diagnosed with wide dissemination in the peritoneum and omentum, limiting the effectiveness of surgery and chemotherapy. In addition, unlike other well-documented cancers, metastasis through vasculature is not a usual dissemination pathway in ovarian cancer. This review sheds light on TAMs and the main process and mechanism of ovarian cancer metastasis.

Keratin-14 (KRT14) Positive Leader Cells Mediate Mesothelial Clearance and Invasion by Ovarian Cancer Cells

Epithelial ovarian cancer metastasis is driven by spheroids, which are heterogeneous cancer cell aggregates released from the primary tumour mass that passively disseminate throughout the peritoneal cavity to promote tumour spread, disease recurrence, and acquired chemoresistance. Despite their clinical importance, the molecular events that control spheroid attachment and invasion into underlying healthy tissues remain poorly understood. We examined a novel in vitro invasion model using imaging mass spectrometry to establish a “snapshot” of the spheroid/mesothelial interface. Amongst numerous adhesion-related proteins, we identified a sub-population of highly motile, invasive cells that expressed the basal epithelial marker KRT14 as an absolute determinant of invasive potential. The loss of KRT14 completely abrogated the invasive capacity, but had no impact on cell viability or proliferation, suggesting an invasion-specific role. Our data demonstrate KRT14 cells as an ovarian cancer “leader cell” phenotype underlying tumor invasion, and suggest their importance as a clinically relevant target in directed anti-tumour therapies.

Pectasol-C Modified Citrus Pectin targets Galectin-3-induced STAT3 activation and synergize paclitaxel cytotoxic effect on ovarian cancer spheroids

Here we sought to determine the relationship between STAT3 activity and Galectin-3 (Gal-3) and to investigate the cytotoxic effect of PectaSol-C Modified Citrus Pectin (Pect-MCP) as a specific competitive inhibitor of Galectin-3 (Gal-3) in combination with Paclitaxel (PTX) to kill the ovarian cancer cell SKOV-3 multicellular tumor spheroid (MCTS). To this order, SKOV-3 cells in 2D and 3D cultures were treated with exogenous Gal-3 for the assessment of STAT3 activity. Two-way ANOVA main effect and IC50 of each drug Paclitaxel (PTX) and Pect-MCP or in combination were obtained from MTT assay results. The phosphorylated STAT3 levels, migration, invasion, integrin mRNA and p-AKTser473 levels were assessed in the absence or presence of each drug alone or in combination. Gal-3 expression levels were assessed in human serous ovarian cancer (SOC) specimens and its correlation with different integrin mRNA levels was further assessed. Our results showed that Gal-3 expression level was significantly increased in MCTS compared to monolayer SKOV-3 cells which triggered STAT3 phosphorylation. Moreover, Pect-MCP synergized with PTX to kill SKOV3 MCTS through abrogation of STAT3 activity and reduced expression of its downstream target HIF-1α, reduced integrin mRNA levels, and subsequently decreased AKT activity. There were higher expression levels of Gal-3 in human high-grade SOC specimens compared to the normal ovary and borderline SOC which positively and significantly correlated with α5, β2 and β6 integrin mRNA levels. Together, these results revealed for the first time that Pect-MCP could be considered as a potential drug to enhance the PTX effect on ovarian cancer cells MCTS through inhibition of STAT3 activity.

Therapeutic Targeting of Collective Invasion in Ovarian Cancer

Ovarian cancer is the seventh most commonly diagnosed cancer amongst women and has the highest mortality rate of all gynaecological malignancies. It is a heterogeneous disease attributed to one of three cell types found within the reproductive milieu: epithelial, stromal, and germ cell. Each histotype differs in etiology, pathogenesis, molecular biology, risk factors, and prognosis. Furthermore, the origin of ovarian cancer remains unclear, with ovarian involvement secondary to the contribution of other gynaecological tissues. Despite these complexities, the disease is often treated as a single entity, resulting in minimal improvement to survival rates since the introduction of platinum-based chemotherapy over 30 years ago. Despite concerted research efforts, ovarian cancer remains one of the most difficult cancers to detect and treat, which is in part due to the unique mode of its dissemination. Ovarian cancers tend to invade locally to neighbouring tissues by direct extension from the primary tumour, and passively to pelvic and distal organs within the peritoneal fluid or ascites as multicellular spheroids. Once at their target tissue, ovarian cancers, like most epithelial cancers including colorectal, melanoma, and breast, tend to invade as a cohesive unit in a process termed collective invasion, driven by specialized cells termed "leader cells". Emerging evidence implicates leader cells as essential drivers of collective invasion and metastasis, identifying collective invasion and leader cells as a viable target for the management of metastatic disease. However, the development of targeted therapies specifically against this process and this subset of cells is lacking. Here, we review our understanding of metastasis, collective invasion, and the role of leader cells in ovarian cancer. We will discuss emerging research into the development of novel therapies targeting collective invasion and the leader cell population.

Modeling the effect of ascites-induced compression on ovarian cancer multicellular aggregates

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy. EOC dissemination is predominantly via direct extension of cells and multicellular aggregates (MCAs) into the peritoneal cavity, which adhere to and induce retraction of peritoneal mesothelium and proliferate in the submesothelial matrix to generate metastatic lesions. Metastasis is facilitated by the accumulation of malignant ascites (500 ml to >2 l), resulting in physical discomfort and abdominal distension, and leading to poor prognosis. Although intraperitoneal fluid pressure is normally subatmospheric, an average intraperitoneal pressure of 30 cmH2O (22.1 mmHg) has been reported in women with EOC. In this study, to enable experimental evaluation of the impact of high intraperitoneal pressure on EOC progression, two new in vitro model systems were developed. Initial experiments evaluated EOC MCAs in pressure vessels connected to an Instron to apply short-term compressive force. A Flexcell Compression Plus system was then used to enable longer-term compression of MCAs in custom-designed hydrogel carriers. Results show changes in the expression of genes related to epithelial-mesenchymal transition as well as altered dispersal of compressed MCAs on collagen gels. These new model systems have utility for future analyses of compression-induced mechanotransduction and the resulting impact on cellular responses related to intraperitoneal metastatic dissemination.This article has an associated First Person interview with the first authors of the paper.

Wnt11 alters integrin and cadherin expression by ovarian cancer spheroids and inhibits tumorigenesis and metastasis

The present study investigated the role of Wnt11 in multicellular tumor spheroid-like structures (MCTS) ovarian cancer cell proliferation, migration and invasion in vitro and in vivo tumorigenesis and metastasis in xenograft nude mice model. Moreover, samples from human serous ovarian cancer (SOC) were used to assess the association of Wnt11 with integrins and cadherins. The data showed that Wnt11 overexpressing SKOV-3 cells became more compact accompanied by increased expression of E-and N-cadherin and lower expression of EpCAM and CD44. The α5, β2, β3 and β6 integrin subunits expression levels were significantly reduced in Wnt11 overexpressing cells accompanied with significantly reduced disaggregation of Wnt11 overexpressing SKOV-3 MCTS on ECM components. Moreover, Wnt11 overexpressing SKOV-3 MCTS showed decreased migration, invasion as well as no tumor growth and metastasis in vivo. We found that Wnt11 significantly and negatively correlated with ITGB2, ITGB6, and EpCAM and positively with CDH-1 in high-grade SOC specimens. Our results suggest that Wnt11 impedes MCTS attachment to ECM components and therefore can affect ovarian cancer progression.

A novel chemotherapeutic protocol for peritoneal metastasis and inhibition of relapse in drug resistant ovarian cancer

The majority of ovarian cancer patients are diagnosed in late stages of the disease, in which the tumor cells have leaked into the peritoneum and are present as tumorspheres. These tumorspheres are rich in cancer stem‐like cells (CSCs), which are resistant to therapy and are a major source of relapse. The purpose of this research was to identify a safe therapeutic approach that could eradicate the peritoneal CSC‐rich tumorspheres and inhibit relapse. Highly metastatic ascitic cells (OVASC‐1) that are resistant to standard‐of‐care chemotherapy due to upregulation of MDR1 gene were obtained from a patient with ovarian carcinoma and recurrent disease. CSC‐rich tumorspheres were generated, characterized, and treated with different chemotherapeutics. The most effective drug combination that could eradicate tumorspheres at nanomolar levels despite upregulation of MDR1 gene was identified. Luciferase‐expressing OVASC‐1 cells were implanted in the peritoneum of nude mice and treated with the identified drug combination. The progression of disease, response to therapy and recurrence were studied by quantitative imaging. Toxicity to abdominal tissues was studied by histopathology. Mice implanted with intraperitoneal (IP) OVASC‐1 xenografts showed limited response to combination therapy with cisplatin/paclitaxel at the maximum tolerated dose. Despite overexpression of MDR1 on OVASC‐1 cells, mice treated with our combination IP low‐dose MMAE and SN‐38 chemotherapy showed complete response without relapse. No signs of toxicity to abdominal tissues were observed. While MMAE and SN‐38 are not administered as free drugs due to their high potency and potential for systemic toxicity, our low‐dose localized therapy approach effectively restricted the cytotoxic effects to the tumor cells in the peritoneum. Consequently, maximum efficacy with minimal adverse effects was achieved. These remarkable results with IP low‐dose combination chemotherapy encourage investigation into its potential clinical application as either first‐line therapy or in cases of acquired resistance to cisplatin and paclitaxel.

The mechanical microenvironment regulates ovarian cancer cell morphology, migration, and spheroid disaggregation

There is growing appreciation of the importance of the mechanical properties of the tumor microenvironment on disease progression. However, the role of extracellular matrix (ECM) stiffness and cellular mechanotransduction in epithelial ovarian cancer (EOC) is largely unknown. Here, we investigated the effect of substrate rigidity on various aspects of SKOV3 human EOC cell morphology and migration. Young’s modulus values of normal mouse peritoneum, a principal target tissue for EOC metastasis, were determined by atomic force microscopy (AFM) and hydrogels were fabricated to mimic these values. We find that cell spreading, focal adhesion formation, myosin light chain phosphorylation, and cellular traction forces all increase on stiffer matrices. Substrate rigidity also positively regulates random cell migration and, importantly, directional increases in matrix tension promote SKOV3 cell durotaxis. Matrix rigidity also promotes nuclear translocation of YAP1, an oncogenic transcription factor associated with aggressive metastatic EOC. Furthermore, disaggregation of multicellular EOC spheroids, a behavior associated with dissemination and metastasis, is enhanced by matrix stiffness through a mechanotransduction pathway involving ROCK, actomyosin contractility, and FAK. Finally, this pattern of mechanosensitivity is maintained in highly metastatic SKOV3ip.1 cells. These results establish that the mechanical properties of the tumor microenvironment may play a role in EOC metastasis.

Ferritin heavy chain is a negative regulator of ovarian cancer stem cell expansion and epithelial to mesenchymal transition

Objectives

Ferritin is the major intracellular iron storage protein essential for maintaining the cellular redox status. In recent years ferritin heavy chain (FHC) has been shown to be involved also in the control of cancer cell growth. Analysis of public microarray databases in ovarian cancer revealed a correlation between low FHC expression levels and shorter survival. To better understand the role of FHC in cancer, we have silenced the FHC gene in SKOV3 cells.

Results

FHC-KO significantly enhanced cell viability and induced a more aggressive behaviour. FHC-silenced cells showed increased ability to form 3D spheroids and enhanced expression of NANOG, OCT4, ALDH and Vimentin. These features were accompanied by augmented expression of SCD1, a major lipid metabolism enzyme. FHC apparently orchestrates part of these changes by regulating a network of miRNAs.

Methods

FHC-silenced and control shScr SKOV3 cells were monitored for changes in proliferation, migration, ability to propagate as 3D spheroids and for the expression of stem cell and epithelial-to-mesenchymal-transition (EMT) markers. The expression of three miRNAs relevant to spheroid formation or EMT was assessed by q-PCR.

Conclusions

In this paper we uncover a new function of FHC in the control of cancer stem cells.

Ascitic fluid from advanced ovarian cancer patients compromises the activity of receptor tyrosine kinase inhibitors in 3D cell clusters of ovarian cancer cells

Ovarian cancer patients in the advanced stages of the disease show clinical ascites, which is associated with a poor prognosis. There is limited understanding of the effect of ascitic fluid on ovarian cancer cells and their response to anticancer drugs. We investigated the antitumour effects of EGFR/Her-2 (canertinib) and c-Met (PHA665752) inhibitors in a 3D cell model of three ovarian cancer lines. Single and combined inhibitor treatments affected cell growth of OVCAR-5 and SKOV-3 cell lines but not OV-90 cell line. Growth reduction was correlated with the down expression of PCNA, EGFR, HER-2, c-MET, ERK and AKT and their phosphorylation status in cells in growth factor supplemented media. However, these effects were not re-producible in OVCAR-5 and SKOV-3 cell lines when they were exposed to ascitic fluid obtained from three ovarian cancer patients. Serum albumin and protein components in the ascitic fluids may reduce the cellular uptake of the inhibitors.

Dietary compound proanthocyanidins from Chinese bayberry (Myrica rubra Sieb. et Zucc.) leaves attenuate chemotherapy-resistant ovarian cancer stem cell traits via targeting the Wnt/β-catenin signaling pathway and inducing G1 cell cycle arrest

Cancer stem cells (CSCs) represent a small population of cancer cells characterized by self-renewal ability, tumorigenesis and drug resistance. Ovarian cancer is one of the leading causes of death related to the female reproductive system in Western countries and has been evaluated as a type of CSC-related cancer in recent years. Natural products have attracted great attention in cancer treatment in recent years due to drug resistance and a high relapse rate of ovarian cancer. Chinese bayberry leaf proanthocyanidins (BLPs) contain epigallocatechin-3-O-gallate as their terminal and major extension units, which is quite unusual in the plant kingdom. BLPs showed strong antioxidant and antiproliferative abilities in previous studies. In the present study, chemotherapy-resistant OVCAR-3 spheroid (SP) cells were obtained by sphere culturing and exhibited CSC-like properties by showing a higher ALDH+ population and higher expression of stemness-related proteins. BLPs exhibited inhibitory effects on the growth and CSC characteristics of OVCAR-3 SP cells by showing decreased cell viability, sphere and colony formation ability, ALDH+ population and expression of stemness-related proteins. BLPs also targeted the Wnt/β-catenin pathway by reducing the expression of β-catenin, cyclin D1 and c-Myc and thus inhibited the self-renewal ability of OVCAR-3 SP cells. Furthermore, BLPs also induced G1 cell cycle arrest in OVCAR-3 SP cells. Taken together, these findings suggested that BLPs may be an important agent in the development of therapeutics for ovarian cancer patients.

TWIST1 induces expression of discoidin domain receptor 2 to promote ovarian cancer metastasis

The mesenchymal gene program has been shown to promote the metastatic progression of ovarian cancer; however, specific proteins induced by this program that lead to these metastatic behaviors have not been identified. Using patient derived tumor cells and established human ovarian tumor cell lines, we find that the Epithelial-to –Mesenchymal Transition inducing factor TWIST1 drives expression of Discoidin Domain Receptor 2 (DDR2), a receptor tyrosine kinase (RTK) that recognizes fibrillar collagen as ligand. The expression and action of DDR2 was critical for mesothelial cell clearance, invasion and migration in ovarian tumor cells. It does so, in part, by upregulating expression and activity of matrix remodeling enzymes that lead to increased cleavage of fibronectin and spreading of tumor cells. Additionally, DDR2 stabilizes SNAIL1, allowing for sustained mesenchymal phenotype. In patient derived ovarian cancer specimens, DDR2 expression correlated with enhanced invasiveness. DDR2 expression was associated with advanced stage ovarian tumors and metastases. In vivo studies demonstrated that the presence of DDR2 is critical for ovarian cancer metastasis. These findings indicate that the collagen receptor DDR2 is critical for multiple steps of ovarian cancer progression to metastasis, and thus, identifies DDR2 as a potential new target for the treatment of metastatic ovarian cancer.

Peritoneal dissemination of ovarian cancer: role of MUC16-mesothelin interaction and implications for treatment

INTRODUCTION

Peritoneal dissemination is a particular form of malignant progression in ovarian cancer, preceding hematogenic or lymphatic dissemination. Thus, prevention of peritoneal implantation of cancer cells is envisioned to inhibit neoplastic dissemination and therefore prolong disease remission and patient's survival. Areas covered: An extended review on the role of MUC16 (CA125) and mesothelin (MSLN), expressed in a high percentage of ovarian carcinomas, indicate that this duet is relevant for the contact between cancer cells and mesothelial cells in homotypic (cancer cell-cancer cell) and heterotypic (cancer cell-mesothelial cell) interactions. This review discusses the reasons underlying the clinical failure of immunotherapeutic strategies targeting MUC16. Clinical data on MSLN targeting agents such as antibody-based immunotoxins or antibody drug conjugates are also reviewed. The promising anti-tumor effect of CAR-T cells directed to MUC16 or MSLN is emphasized. New emerging strategies specifically disrupting the MUC16-MSLN interaction are at the forefront of this review, including TRAIL ligands bound to MSLN targeting MUC16 expressing cells and single chain monoclonal antibodies and immunoadhesins recognizing MSLN-MUC16 binding domains. Expert commentary: Based on existing evidences the authors advocate that agents targeting MUC16-MSLN may add to the therapeutic armamentarium directed to abrogate peritoneal homing of ovarian cancer.

miR-509-3p is clinically significant and strongly attenuates cellular migration and multi-cellular spheroids in ovarian cancer

Ovarian cancer presents as an aggressive, advanced stage cancer with widespread metastases that depend primarily on multicellular spheroids in the peritoneal fluid. To identify new druggable pathways related to metastatic progression and spheroid formation, we integrated microRNA and mRNA sequencing data from 293 tumors from The Cancer Genome Atlas (TCGA) ovarian cancer cohort. We identified miR-509-3p as a clinically significant microRNA that is more abundant in patients with favorable survival in both the TCGA cohort (P = 2.3E–3), and, by in situ hybridization (ISH), in an independent cohort of 157 tumors (P < 1.0E–3). We found that miR-509-3p attenuated migration and disrupted multi-cellular spheroids in HEYA8, OVCAR8, SKOV3, OVCAR3, OVCAR4 and OVCAR5 cell lines. Consistent with disrupted spheroid formation, in TCGA data miR-509-3p's most strongly anti-correlated predicted targets were enriched in components of the extracellular matrix (ECM). We validated the Hippo pathway effector YAP1 as a direct miR-509-3p target. We showed that siRNA to YAP1 replicated 90% of miR-509-3p-mediated migration attenuation in OVCAR8, which contained high levels of YAP1 protein, but not in the other cell lines, in which levels of this protein were moderate to low. Our data suggest that the miR-509-3p/YAP1 axis may be a new druggable target in cancers with high YAP1, and we propose that therapeutically targeting the miR-509-3p/YAP1/ECM axis may disrupt early steps in multi-cellular spheroid formation, and so inhibit metastasis in epithelial ovarian cancer and potentially in other cancers.

Vitronectin (Vn) glycosylation patterned by lectin affinity assays-A potent glycoproteomic tool to discriminate plasma Vn from cancer ascites Vn

Changes in glycosylation have been associated with human cancer, but their complexity poses an analytical challenge. Ovarian cancer is a major cause of death in women because of an often late diagnosis. At least one-third of patients presents ascites fluid at diagnosis, and almost all have ascites at recurrence. Vitronectin (Vn) is a multifunctional glycoprotein that is suggested to be implicated in ovarian cancer metastasis and is found within ascites. The present study evaluated the potential of using lectin affinity for characterizing the glycosylation pattern of Vn. Human Vn was purified from 1 sample of ovarian cancer ascites or a pool of plasma samples. Consistent findings were observed with both dot blot and lectin array assays. Based on a panel of 40 lectins, the lectin array revealed discriminant patterns of lectin binding to Vn glycans. Interestingly, almost all the highlighted interactions were found to be higher with Vn from ascites relative to the plasma counterpart. Also, the lectin array was able to discriminate profiles of lectin interactions (ConA, SNA-I, PHA-E, PHA-L) between Vn samples that were not evident using dot blot, indicating its high sensitivity. The model of ConA binding during thermal unfolding of Vn confirmed the higher accessibility of mannosylated glycans in Vn from ascites as monitored by turbidimetry. Thus, this study demonstrated the usefulness of lectins and the lectin array as a glycoproteomic tool for high throughput and sensitive analysis of glycosylation patterns. Our data provide novel insights concerning Vn glycosylation patterns in clinical specimens, paving the way for further investigations regarding their functional impact and clinical interest.

Development of Peritoneal Carcinomatosis in Epithelial Ovarian Cancer: A Review

Epithelial ovarian cancer (EOC) metastasizes intra-abdominally with often numerous, superficial, small-sized lesions. This so-called peritoneal carcinomatosis is difficult to treat, and peritoneal recurrences are frequently observed, leading to a poor prognosis. Underlying mechanisms of interactions between EOC and peritoneal cells are incompletely understood. This review summarizes and discusses the development of peritoneal carcinomatosis from a cell-biological perspective, focusing on characteristics of EOC and peritoneal cells. We aim to provide insight into how peritoneum facilitates tumor adhesion but limits size of lesions and depth of invasion. The development of peritoneal carcinomatosis is a multistep process that requires adaptations of EOC and peritoneal cells. Mechanisms that enable tumor adhesion and growth involve cadherin restructuring on EOC cells, integrin-mediated adhesion, and mesothelial evasion by mechanical forces driven by integrin-ligand interactions. Clinical trials targeting these mechanisms, however, showed only limited effects. Other factors that inhibit tumor growth and deep invasion are virtually unknown. Future studies are needed to elucidate the exact mechanisms that underlie the development and limited growth of peritoneal carcinomatosis. This review on development of peritoneal carcinomatosis of EOC summarizes the current knowledge and its limitations. Clarification of the stepwise process may inspire future research to investigate new treatment approaches of peritoneal carcinomatosis.

SOX2 is required to maintain cancer stem cells in ovarian cancer

Ovarian cancer cells can form spheroids under serum‐free suspension culture conditions. The spheroids, which are enriched in cancer stem cells, can result in tumor dissemination and relapse. To identify new targetable molecules in ovarian cancer spheroids, we investigated the differential expression of genes in spheroids compared with that under monolayer culture conditions by qPCR microarray. We identified that SOX2 is overexpressed in spheroids. We then proved that SOX2 expression was increased in successive spheroid generations. Besides, knockdown of SOX2 expression in SKOV3 or HO8910 ovarian cancer spheroid cells decreased spheroid formation, cell proliferation, cell migration, resistance to Cisplatin treatment, tumorigenicity, and the expression of stemness‐related genes and epithelial to mesenchymal transition‐related genes, whereas overexpression of SOX2 in SKOV3 or HO8910 ovarian cancer cells showed the opposite effects. In addition, we found that SOX2 expression was closely associated with chemo‐resistance and poor prognosis in EOC patients. These results strongly suggest that SOX2 is required to maintain cancer stem cells in ovarian cancer. Targeting SOX2 in ovarian cancer may be therapeutically beneficial.

E-cadherin: A determinant molecule associated with ovarian cancer progression, dissemination and aggressiveness

Ovarian cancer (OC) is the fifth cancer death cause in women worldwide. The malignant nature of this disease stems from its unique dissemination pattern. Epithelial-to-mesenchymal transition (EMT) has been reported in OC and downregulation of Epithelial cadherin (E-cadherin) is a hallmark of this process. However, findings on the relationship between E-cadherin levels and OC progression, dissemination and aggressiveness are controversial. In this study, the evaluation of E-cadherin expression in an OC tissue microarray revealed its prognostic value to discriminate between advanced- and early-stage tumors, as well as serous tumors from other histologies. Moreover, E-cadherin, Neural cadherin (N-cadherin), cytokeratins and vimentin expression was assessed in TOV-112, SKOV-3, OAW-42 and OV-90 OC cell lines grown in monolayers and under anchorage-independent conditions to mimic ovarian tumor cell dissemination, and results were associated with cell aggressiveness. According to these EMT-related markers, cell lines were classified as mesenchymal (M; TOV-112), intermediate mesenchymal (IM; SKOV-3), intermediate epithelial (IE; OAW-42) and epithelial (E; OV-90). M- and IM-cells depicted the highest migration capacity when grown in monolayers, and aggregates derived from M- and IM-cell lines showed lower cell death, higher adhesion to extracellular matrices and higher invasion capacity than E- and IE-aggregates. The analysis of E-cadherin, N-cadherin, cytokeratin 19 and vimentin mRNA levels in 20 advanced-stage high-grade serous human OC ascites showed an IM phenotype in all cases, characterized by higher proportions of N- to E-cadherin and vimentin to cytokeratin 19. In particular, higher E-cadherin mRNA levels were associated with cancer antigen 125 levels more than 500 U/mL and platinum-free intervals less than 6 months. Altogether, E-cadherin expression levels were found relevant for the assessment of OC progression and aggressiveness.

E-cadherin: A determinant molecule associated with ovarian cancer progression, dissemination and aggressiveness

Ovarian cancer (OC) is the fifth cancer death cause in women worldwide. The malignant nature of this disease stems from its unique dissemination pattern. Epithelial-to-mesenchymal transition (EMT) has been reported in OC and downregulation of Epithelial cadherin (E-cadherin) is a hallmark of this process. However, findings on the relationship between E-cadherin levels and OC progression, dissemination and aggressiveness are controversial. In this study, the evaluation of E-cadherin expression in an OC tissue microarray revealed its prognostic value to discriminate between advanced- and early-stage tumors, as well as serous tumors from other histologies. Moreover, E-cadherin, Neural cadherin (N-cadherin), cytokeratins and vimentin expression was assessed in TOV-112, SKOV-3, OAW-42 and OV-90 OC cell lines grown in monolayers and under anchorage-independent conditions to mimic ovarian tumor cell dissemination, and results were associated with cell aggressiveness. According to these EMT-related markers, cell lines were classified as mesenchymal (M; TOV-112), intermediate mesenchymal (IM; SKOV-3), intermediate epithelial (IE; OAW-42) and epithelial (E; OV-90). M- and IM-cells depicted the highest migration capacity when grown in monolayers, and aggregates derived from M- and IM-cell lines showed lower cell death, higher adhesion to extracellular matrices and higher invasion capacity than E- and IE-aggregates. The analysis of E-cadherin, N-cadherin, cytokeratin 19 and vimentin mRNA levels in 20 advanced-stage high-grade serous human OC ascites showed an IM phenotype in all cases, characterized by higher proportions of N- to E-cadherin and vimentin to cytokeratin 19. In particular, higher E-cadherin mRNA levels were associated with cancer antigen 125 levels more than 500 U/mL and platinum-free intervals less than 6 months. Altogether, E-cadherin expression levels were found relevant for the assessment of OC progression and aggressiveness.

E-cadherin: A determinant molecule associated with ovarian cancer progression, dissemination and aggressiveness

Ovarian cancer (OC) is the fifth cancer death cause in women worldwide. The malignant nature of this disease stems from its unique dissemination pattern. Epithelial-to-mesenchymal transition (EMT) has been reported in OC and downregulation of Epithelial cadherin (E-cadherin) is a hallmark of this process. However, findings on the relationship between E-cadherin levels and OC progression, dissemination and aggressiveness are controversial. In this study, the evaluation of E-cadherin expression in an OC tissue microarray revealed its prognostic value to discriminate between advanced- and early-stage tumors, as well as serous tumors from other histologies. Moreover, E-cadherin, Neural cadherin (N-cadherin), cytokeratins and vimentin expression was assessed in TOV-112, SKOV-3, OAW-42 and OV-90 OC cell lines grown in monolayers and under anchorage-independent conditions to mimic ovarian tumor cell dissemination, and results were associated with cell aggressiveness. According to these EMT-related markers, cell lines were classified as mesenchymal (M; TOV-112), intermediate mesenchymal (IM; SKOV-3), intermediate epithelial (IE; OAW-42) and epithelial (E; OV-90). M- and IM-cells depicted the highest migration capacity when grown in monolayers, and aggregates derived from M- and IM-cell lines showed lower cell death, higher adhesion to extracellular matrices and higher invasion capacity than E- and IE-aggregates. The analysis of E-cadherin, N-cadherin, cytokeratin 19 and vimentin mRNA levels in 20 advanced-stage high-grade serous human OC ascites showed an IM phenotype in all cases, characterized by higher proportions of N- to E-cadherin and vimentin to cytokeratin 19. In particular, higher E-cadherin mRNA levels were associated with cancer antigen 125 levels more than 500 U/mL and platinum-free intervals less than 6 months. Altogether, E-cadherin expression levels were found relevant for the assessment of OC progression and aggressiveness.

Cadherin composition and multicellular aggregate invasion in organotypic models of epithelial ovarian cancer intraperitoneal metastasis

During epithelial ovarian cancer (EOC) progression, intraperitoneally disseminating tumor cells and multi-cellular aggregates (MCAs) present in ascites fluid adhere to the peritoneum and induce retraction of the peritoneal mesothelial monolayer prior to invasion of the collagen-rich sub-mesothelial matrix and proliferation into macro-metastases. Clinical studies have shown heterogeneity among EOC metastatic units with respect to cadherin expression profiles and invasive behavior, however the impact of distinct cadherin profiles on peritoneal anchoring of metastatic lesions remains poorly understood. In the current study, we demonstrate that metastasis-associated behaviors of ovarian cancer cells and MCAs are influenced by cellular cadherin composition. Our results show that mesenchymal N-cadherin expressing (Ncad+) cells and MCAs invade much more efficiently than E-cadherin expressing (Ecad+) cells. Ncad+ MCAs exhibit rapid lateral dispersal prior to penetration of three-dimensional collagen matrices. When seeded as individual cells, lateral migration and cell-cell junction formation precede matrix invasion. Neutralizing the Ncad extracellular domain with the monoclonal antibody GC-4 suppresses lateral dispersal and cell penetration of collagen gels. In contrast, use of a broad spectrum matrix metalloproteinase (MMP) inhibitor (GM6001) to block endogenous membrane type 1 matrix metalloproteinase (MT1-MMP) activity does not fully inhibit cell invasion. Using intact tissue explants, Ncad+ MCAs were also shown to efficiently rupture peritoneal mesothelial cells, exposing the sub-mesothelial collagen matrix. Acquisition of Ncad by E-cadherin expressing cells (Ecad+) increased mesothelial clearance activity, but was not sufficient to induce matrix invasion. Furthermore, co-culture of Ncad+ with Ecad+ cells did not promote a “leader-follower” mode of collective cell invasion, demonstrating that matrix remodeling and creation of invasive micro-tracks are not sufficient for cell penetration of collagen matrices in the absence of Ncad. Collectively, our data emphasize the role of Ncad in intraperitoneal seeding of EOC and provide the rationale for future studies targeting Ncad+ in pre-clinical models of EOC metastasis.

Heterogeneous Cadherin Expression and Multicellular Aggregate Dynamics in Ovarian Cancer Dissemination

Epithelial ovarian carcinoma spreads via shedding of cells and multicellular aggregates (MCAs) from the primary tumor into peritoneal cavity, with subsequent intraperitoneal tumor cell:mesothelial cell adhesion as a key early event in metastatic seeding. Evaluation of human tumor extracts and tissues confirms that well-differentiated ovarian tumors express abundant E-cadherin (Ecad), whereas advanced lesions exhibit upregulated N-cadherin (Ncad). Two expression patterns are observed: “mixed cadherin,” in which distinct cells within the same tumor express either E- or Ncad, and “hybrid cadherin,” wherein single tumor cell(s) simultaneously expresses both cadherins. We demonstrate striking cadherin-dependent differences in cell-cell interactions, MCA formation, and aggregate ultrastructure. Mesenchymal-type Ncad+ cells formed stable, highly cohesive solid spheroids, whereas Ecad+ epithelial-type cells generated loosely adhesive cell clusters covered by uniform microvilli. Generation of “mixed cadherin” MCAs using fluorescently tagged cell populations revealed preferential sorting into cadherin-dependent clusters, whereas mixing of cell lines with common cadherin profiles generated homogeneous aggregates. Recapitulation of the “hybrid cadherin” Ecad+/Ncad+ phenotype, via insertion of the CDH2 gene into Ecad+ cells, resulted in the ability to form heterogeneous clusters with Ncad+ cells, significantly enhanced adhesion to organotypic mesomimetic cultures and peritoneal explants, and increased both migration and matrix invasion. Alternatively, insertion of CDH1 gene into Ncad+ cells greatly reduced cell-to-collagen, cell-to-mesothelium, and cell-to-peritoneum adhesion. Acquisition of the hybrid cadherin phenotype resulted in altered MCA surface morphology with increased surface projections and increased cell proliferation. Overall, these findings support the hypothesis that MCA cadherin composition impacts intraperitoneal cell and MCA dynamics and thereby affects ultimate metastatic success.