Mesenchymal cell interaction with ovarian cancer cells triggers pro-metastatic properties

The Effects of Natural Epigenetic Therapies in 3D Ovarian Cancer and Patient-Derived Tumor Explants: New Avenues in Regulating the Cancer Secretome

High mortality rates in ovarian cancer have been linked to recurrence, metastasis, and chemoresistant disease, which are known to involve not only genetic changes but also epigenetic aberrations. In ovarian cancer, adipose-derived stem cells from the omentum (O-ASCs) play a crucial role in supporting the tumor and its tumorigenic microenvironment, further propagating epigenetic abnormalities and dissemination of the disease. Epigallocatechin gallate (EGCG), a DNA methyltransferase inhibitor derived from green tea, and Indole-3-carbinol (I3C), a histone deacetylase inhibitor from cruciferous vegetables, carry promising effects in reprograming aberrant epigenetic modifications in cancer. Therefore, we demonstrate the action of these diet-derived compounds in suppressing the growth of 3D ovarian cancer spheroids or organoids as well as post-treatment cancer recovery through proliferation, migration, invasion, and colony formation assays when compared to the synthetic epigenetic compound Panobinostat with or without standard chemotherapy. Finally, given the regulatory role of the secretome in growth, metastasis, chemoresistance, and relapse of disease, we demonstrate that natural epigenetic compounds can regulate the secretion of protumorigenic growth factors, cytokines, extracellular matrix components, and immunoregulatory markers in human ovarian cancer specimens. While further studies are needed, our results suggest that these treatments could be considered in the future as adjuncts to standard chemotherapy, improving efficiency and patient outcomes.

Mechanobiology of cancer cell responsiveness to chemotherapy and immunotherapy: Mechanistic insights and biomaterial platforms

Mechanical forces are central to how cancer treatments such as chemotherapeutics and immunotherapies interact with cells and tissues. At the simplest level, electrostatic forces underlie the binding events that are critical to therapeutic function. However, a growing body of literature points to mechanical factors that also affect whether a drug or an immune cell can reach a target, and to interactions between a cell and its environment affecting therapeutic efficacy. These factors affect cell processes ranging from cytoskeletal and extracellular matrix remodeling to transduction of signals by the nucleus to metastasis of cells. This review presents and critiques the state of the art of our understanding of how mechanobiology impacts drug and immunotherapy resistance and responsiveness, and of the in vitro systems that have been of value in the discovery of these effects.

Personalized models of heterogeneous 3D epithelial tumor microenvironments: Ovarian cancer as a model

Intractable human diseases such as cancers, are context dependent, unique to both the individual patient and to the specific tumor microenvironment. However, conventional cancer treatments are often nonspecific, targeting global similarities rather than unique drivers. This limits treatment efficacy across heterogeneous patient populations and even at different tumor locations within the same patient. Ultimately, this poor efficacy can lead to adverse clinical outcomes and the development of treatment-resistant relapse. To prevent this and improve outcomes, it is necessary to be selective when choosing a patient's optimal adjuvant treatment. In this review, we posit the use of personalized, tumor-specific models (TSM) as tools to achieve this remarkable feat. First, using ovarian cancer as a model disease, we outline the heterogeneity and complexity of both the cellular and extracellular components in the tumor microenvironment. Then we examine the advantages and disadvantages of contemporary cancer models and the rationale for personalized TSM. We discuss how to generate precision 3D models through careful and detailed analysis of patient biopsies. Finally, we provide clinically relevant applications of these versatile personalized cancer models to highlight their potential impact. These models are ideal for a myriad of fundamental cancer biology and translational studies. Importantly, these approaches can be extended to other carcinomas, facilitating the discovery of new therapeutics that more effectively target the unique aspects of each individual patient's TME. STATEMENT OF SIGNIFICANCE: In this article, we have presented the case for the application of biomaterials in developing personalized models of complex diseases such as cancers. TSM could bring about breakthroughs in the promise of precision medicine. The critical components of the diverse tumor microenvironments, that lead to treatment failures, include cellular- and extracellular matrix- heterogeneity, and biophysical signals to the cells. Therefore, we have described these dynamic components of the tumor microenvironments, and have highlighted how contemporary biomaterials can be utilized to create personalized in vitro models of cancers. We have also described the application of the TSM to predict the dynamic patterns of disease progression, and predict effective therapies that can produce durable responses, limit relapses, and treat any minimal residual disease.

An Overview of Ovarian Cancer: Molecular Processes Involved and Development of Target-based Chemotherapeutics

Ovarian cancer is one of the leading gynecologic diseases with a high mortality rate worldwide. Current statistical studies on cancer reveal that over the past two decades, the fifth most common cause of death related to cancer in females of the western world is ovarian cancer. In spite of significant strides made in genomics, proteomics and radiomics, there has been little progress in transitioning these research advances into effective clinical administration of ovarian cancer. Consequently, researchers have diverted their attention to finding various molecular processes involved in the development of this cancer and how these processes can be exploited to develop potential chemotherapeutics to treat this cancer. The present review gives an overview of these studies which may update the researchers on where we stand and where to go further. The unfortunate situation with ovarian cancer that still exists is that most patients with it do not show any symptoms until the disease has moved to an advanced stage. Undoubtedly, several targets-based drugs have been developed to treat it, but drug-resistance and the recurrence of this disease are still a problem. For the development of potential chemotherapeutics for ovarian cancer, however, some theoretical approaches have also been applied. A description of such methods and their success in this direction is also covered in this review.

Role of exosomes in the immune microenvironment of ovarian cancer

Exosomes are excretory vesicles that can deliver a variety of bioactive cargo molecules to the extracellular environment. Accumulating evidence demonstrates exosome participation in intercellular communication, immune response, inflammatory response and they even play an essential role in affecting the tumor immune microenvironment. The role of exosomes in the immune microenvironment of ovarian cancer is mainly divided into suppression and stimulation. On one hand exosomes can stimulate the innate and adaptive immune systems by activating dendritic cells (DCs), natural killer cells and T cells, allowing these immune cells exert an antitumorigenic effect. On the other hand, ovarian cancer-derived exosomes initiate cross-talk with immunosuppressive effector cells, which subsequently cause immune evasion; one of the hallmarks of cancer. Exosomes induce the polarization of macrophages in M2 phenotype and induce apoptosis of lymphocytes and DCs. Exosomes further activate additional immunosuppressive effector cells (myeloid-derived suppressor cells and regulatory T cells) that induce fibroblasts to differentiate into cancer-associated fibroblasts. Exosomes also induce the tumorigenicity of mesenchymal stem cells to exert additional immune suppression. Furthermore, besides mediating the intercellular communication, exosomes carry microRNAs (miRNAs), proteins and lipids to the tumor microenvironment, which collectively promotes ovarian cancer cells to proliferate, invade and tumors to metastasize. Studying proteins, lipids and miRNAs carried by exosomes could potentially be used as an early diagnostic marker of ovarian cancer for designing treatment strategies.

The hallmarks of ovarian cancer stem cells and niches: Exploring their harmonious interplay in therapy resistance

The concept of a "cancer stem cell" has evolved over the past decades, and research on cancer stem cell biology has entered into a stage of remarkable progress. Cancer stem cells are a major determining factor contributing to the establishment of phenotypic and functional intratumoral heterogeneity in synchronization with their surrounding "cancer stem cell niches." They serve as the driving force for cancer initiation, metastasis, and therapeutic resistance in various types of malignancies. In verity, reciprocal interplay between ovarian cancer stem cells and their niches involves a complex but ingeniously orchestrated tumor microenvironment within the intraperitoneal milieu and especially contribute to chemotherapy resistance in patients with advanced ovarian cancer. Herein, we review the principles of our current understanding of the biological features of ovarian cancer stem cells, focusing mainly on the precise mechanisms underlying acquired chemotherapy resistance. Furthermore, we highlight the specific roles of various cancer-associated stromal and immune cells in creating possible cancer stem cell niches that regulate ovarian cancer stemness.

Design, synthesis, biological evaluation and molecular dynamics of LAR inhibitors

In this study, firstly, the pharmacophore model was established based on LAR inhibitors. ZINC database and drug-like database were screened by Hypo-1-LAR model, and the embryonic compound ZINC71414996 was obtained. Based on this compound, we designed 9 compounds. Secondly, the synthetic route of the compound was determined by consulting Reaxys and Scifinder databases, and 9 compounds (1a-1i) were synthesized by nucleophilic substitution, Suzuki reaction and so on. Meanwhile, their structures were confirmed by ¹H NMR and ¹³C NMR. Thirdly, the Enzymatic assays was carried out, the biological evaluation of compounds 1a-1i led to the identification of a novel PTP-LAR inhibitor 1c, which displayed an IC₅₀ value of 4.8 μM. At last, molecular dynamics simulation showed that compounds could interact strongly with the key amino acids LYS1350, LYS1352, ARG1354, TYR1355, LYS1433, ASP1435, TRP1488, ASP1490, VAL1493, SER1523, ARG1528, ARG1561, GLN1570, LYS1681, thereby inhibiting the protein activity. This study constructed the pharmacophore model of LAR protein, designed small-molecule inhibitors, conducted compound synthesis and enzyme activity screening, so as to provide a basis for searching for drug-capable lead compounds.

Flavonoids Restore Platinum Drug Sensitivity to Ovarian Carcinoma Cells in a Phospho-ERK1/2-Dependent Fashion

Ovarian cancer (OC) is the second most common type of gynecological malignancy; it has poor survival rates and is frequently (>75%) diagnosed at an advanced stage. Platinum-based chemotherapy, with, e.g., carboplatin, is the standard of care for OC, but toxicity and acquired resistance to therapy have proven challenging. Despite advances in OC diagnosis and treatment, approximately 85% of patients will experience relapse, mainly due to chemoresistance. The latter is attributed to alterations in the cancer cells and is also mediated by tumor microenvironment (TME). Recently, we reported the synthesis of a platinum (IV) prodrug that exhibits equal potency toward platinum-sensitive and resistant OC cell lines. Here, we investigated the effect of TME on platinum sensitivity. Co-culture of OC cells with murine or human mesenchymal stem cells (MS-5 and HS-5, respectively) rendered them resistant to chemotherapeutic agents, including platinum, paclitaxel and colchicine. Platinum resistance was also conferred by co-culture with differentiated murine adipocyte progenitor cells. Exposure of OC cells to chemotherapeutic agents resulted in activation of phospho-ERK1/2. Co-culture with MS-5, which conferred drug resistance, was accompanied by blockage of phospho-ERK1/2 activation. The flavonoids fisetin and quercetin were active in restoring ERK phosphorylation, as well as sensitivity to platinum compounds. Exposure of OC cells to cobimetinib-a MEK1 inhibitor that also inhibits extracellular signal-regulated kinase (ERK) phosphorylation-which resulted in reduced sensitivity to the platinum compound. This suggests that ERK activity is involved in mediating the function of flavonoids in restoring platinum sensitivity to OC co-cultured with cellular components of the TME. Our data show the potential of combining flavonoids with standard therapy to restore drug sensitivity to OC cells and overcome TME-mediated platinum drug resistance.

Small Extracellular Vesicles Released from Ovarian Cancer Spheroids in Response to Cisplatin Promote the Pro-Tumorigenic Activity of Mesenchymal Stem Cells

Despite the different strategies used to treat ovarian cancer, around 70% of women/patients eventually fail to respond to the therapy. Cancer stem cells (CSCs) play a role in the treatment failure due to their chemoresistant properties. This capacity to resist chemotherapy allows CSCs to interact with different components of the tumor microenvironment, such as mesenchymal stem cells (MSCs), and thus contribute to tumorigenic processes. Although the participation of MSCs in tumor progression is well understood, it remains unclear how CSCs induce the pro-tumorigenic activity of MSCs in response to chemotherapy. Small extracellular vesicles, including exosomes, represent one possible way to modulate any type of cell. Therefore, in this study, we evaluate if small extracellular vesicle (sEV) derived from ovarian cancer spheroids (OCS), which are enriched in CSCs, can modify the activity of MSCs to a pro-tumorigenic phenotype. We show that sEV released by OCS in response to cisplatin induce an increase in the migration pattern of bone marrow MSCs (BM-MSCs) and the secretion interleukin-6 (IL-6), interleukin-8 (IL-8), and vascular endothelial growth factor A (VEGFA). Moreover, the factors secreted by BM-MSCs induce angiogenesis in endothelial cells and the migration of low-invasive ovarian cancer cells. These findings suggest that cisplatin could modulate the cargo of sEV released by CSCs, and these exosomes can further induce the pro-tumorigenic activity of MSCs.

High Expression of HLA-G in Ovarian Carcinomatosis: The Role of Interleukin-1β

The present study focuses on the influence of the tumor microenvironment on the expression of HLA-G in ovarian cancer and its impact on immune cells. We used carcinomatosis fluids (n = 16) collected from patients diagnosed with epithelial ovarian cancer, detected by an increase in CA125 levels. Our results indicate that HLA-G is expressed by 1) ascitic cell clusters, 2) stromal cells (hospicells) extracted from cancer cell clusters, and 3) cancer cell lines and tumor cells. The origin of HLA-G was linked to inflammatory cytokines present in the cancer microenvironment. In parallel, the ascitic fluid of patients with ovarian cancer contains soluble HLA-G (sHLA-G). The mesothelial cell layer and submesothelial tissues, as well as the immune cell infiltrate, do not secrete HLA-G. In contrast, sHLA-G is absorbed by peritoneal tissues along with mesothelial layers as well as immune cell infiltrates. We demonstrated that interleukin-1β along with TGF-β can be a major HLA-G-inducing factor that upregulates HLA-G expression through the NF-κB pathway. The level of HLA-G in ascites correlated positively with the expression of T regulatory (T-regs) cells, while it negatively correlated with the expression of natural killer and memory cells in tumor-infiltrating immune cells. In conclusion, the production of HLA-G is associated with the presence of inflammatory cytokines and is strongly correlated with microenvironment tolerant cells such as T-regs and diminution of NK and memory T cells.

An evolving story of the metastatic voyage of ovarian cancer cells: cellular and molecular orchestration of the adipose-rich metastatic microenvironment

Metastasis is a complex multistep process that involves critical interactions between cancer cells and a variety of stromal components in the tumor microenvironment, which profoundly influence the different aspects of the metastatic cascade and organ tropism of disseminating cancer cells. Ovarian cancer is the most lethal gynecological malignancy and is characterized by peritoneal disseminated metastasis. Evidence has demonstrated that ovarian cancer possesses specific metastatic tropism for the adipose-rich omentum, which has a pivotal role in the creation of the metastatic tumor microenvironment in the intraperitoneal cavity. Considering the distinct biology of ovarian cancer metastasis, the elucidation of the cellular and molecular mechanisms underlying the reciprocal interplay between ovarian cancer cells and surrounding stromal cell types in the adipose-rich metastatic microenvironment will provide further insights into the development of novel therapeutic approaches for patients with advanced ovarian cancer. Herein, we review the biological mechanisms that regulate the highly orchestrated crosstalk between ovarian cancer cells and various cancer-associated stromal cells in the metastatic tumor microenvironment with regard to the omentum by illustrating how different stromal cells concertedly contribute to the development of ovarian cancer metastasis and metastatic tropism for the omentum.

Proteomic analysis of exosomes reveals an association between cell invasiveness and exosomal bioactivity on endothelial and mesenchymal cell migration in vitro

Ovarian cancer has resulted in over 140 000 deaths reported annually worldwide. This is often attributed to cellular changes in the microenvironment, including increased migration of mesenchymal stem cells (MSCs) and endothelial cells (ECs) to facilitate metastasis. Recently, the ability of exosomes to communicate signals between cells (and promote cancer progression) has been established. In the present study, we explored the effect of exosomes on cells present in the tumour microenvironment. Exosomes were isolated from ovarian cancer cells with different invasive capacity (high = SKOV-3 and low = OVCAR-3) by differential and buoyant density centrifugation and characterised using nanoparticle tracking analysis (NTA), Western blot, and EM. Exosome secretion was positively correlated with invasiveness of releasing cells. Proteomic analyses identified common and unique proteins between exosomes from SKOV-3 and OVCAR-3 with gene ontology analyses revealing that these exosomes are involved in the regulation of cell migration. Since the tumour microenvironment contains multiple cell types, including MSCs and ECs, we examined the effect of these exosomes on MSC and EC migration. Exosomes promoted MSC and EC migration in a time- and concentration-dependent manner. The effect of exosomes isolated from SKOV-3 on cell migration was significantly higher compared with exosomes from OVCAR-3. Thus, we suggest that exosomes from ovarian cancer cells contain a specific set of proteins that are representative of its cell of origin and the invasive capacity.

IFNα-Expressing Amniotic Fluid-Derived Mesenchymal Stem Cells Migrate to and Suppress HeLa Cell-Derived Tumors in a Mouse Model

Background

Immunotherapy for cervical cancer with type I interferon (IFN) is limited because of the cytotoxicity that accompanies the high doses that are administered. In this study, we investigated the utilization of amniotic fluid-derived mesenchymal stem cells (AF-MSCs) as a means for delivering IFNα to local tumor sites for the suppression of cervical cancer in a mouse model using HeLa cell xenografts.

Methods

The tumor tropism ability of AF-MSCs and AF-MSCs genetically modified to overexpress IFNα (IFNα-AF-MSCs) was examined through Transwell in vitro and through fluorescent images and immunohistochemistry in a mouse model. Tumor size and tumor apoptosis were observed to evaluate the efficacy of the targeting therapy. Mechanistically, tumor cell apoptosis was detected by cytometry and TUNEL, and oncogenic proteins c-Myc, p53, and Bcl-2 as well as microvessel density were detected by immunohistochemistry.

Results

In this model, intravenously injected AF-MSCs selectively migrated to the tumor sites, participated in tumor construction, and promoted tumor growth. After being genetically modified to overexpress IFNα, the IFNα-AF-MSCs maintained their tumor tropism but could significantly suppress tumor growth. The restrictive efficacy of IFNα-AF-MSCs was associated with the suppression of angiogenesis, inhibition of tumor cell proliferation, and induction of apoptosis in tumor cells. Neither AF-MSCs nor IFNα-AF-MSCs trigger tumor formation.

Conclusions

IFNα-AF-MSC-based therapy is feasible and shows potential for treating cervical cancer, suggesting that AF-MSCs may be promising vehicles for delivering targeted anticancer therapy.

CCL2/CCL5 secreted by the stroma induce IL-6/PYK2 dependent chemoresistance in ovarian cancer

BACKGROUND

Minimal residual disease is the main issue of advanced ovarian cancer treatment. According to the literature and previous results, we hypothesized that Mesenchymal Stromal Cells (MSC) could support this minimal residual disease by protecting ovarian cancer cells (OCC) from chemotherapy. In vitro study confirmed that MSC could induce OCC chemoresistance without contact using transwell setting. Further experiments showed that this induced chemoresistance was dependent on IL-6 OCC stimulation.

METHODS

We combined meticulous in vitro profiling and tumor xenograft models to study the role of IL-6 in MSC/OCC intereactions.

RESULTS

We demonstrated that Tocilizumab® (anti-IL-6R therapy) in association with chemotherapy significantly reduced the peritoneal carcinosis index (PCI) than chemotherapy alone in mice xenografted with OCCs+MSCs. Further experiments showed that CCL2 and CCL5 are released by MSC in transwell co-culture and induce OCCs IL-6 secretion and chemoresistance. Finally, we found that IL-6 induced chemoresistance was dependent on PYK2 phosphorylation.

CONCLUSIONS

These findings highlight the potential key role of the stroma in protecting minimal residual disease from chemotherapy, thus favoring recurrences. Future clinical trials targeting stroma could use anti-IL-6 therapy in association with chemotherapy.

Extracellular vesicles in ovarian cancer: applications to tumor biology, immunotherapy and biomarker discovery

In recent years there has been tremendous interest in both the basic biology and applications of extracellular vesicles (EVs) in translational cancer research. This includes a better understanding of their biogenesis and mechanisms of selective cargo packaging, their precise roles in horizontal communication, and their application as non-invasive biomarkers. The rapid advances in next-generation omics technologies are the driving forces for these discoveries. In this review, the authors focus on recent results of EV research in ovarian cancer. A deeper understanding of ovarian cancer-derived EVs, the types of cargo molecules and their biological roles in cancer growth, metastases and drug resistance, could have significant impact on the discovery of novel biomarkers and innovative therapeutics. Insights into the role of EVs in immune regulation could lead to novel approaches built on EV-based immunotherapy.

Interleukin-6 from Ovarian Mesenchymal Stem Cells Promotes Proliferation, Sphere and Colony Formation and Tumorigenesis of an Ovarian Cancer Cell Line SKOV3

The origin of the majority of epithelial ovarian cancers (EOC) is regarded as extraovarian, with the ovary being the secondary site. The aim of this study was to explore the possible role of ovarian mesenchymal stem cells (OvMSCs) and secreted IL-6 in the development of EOC. OvMSCs were derived from normal ovarian stroma. Cell surface markers and differentiation capability were determined. The effects of IL-6 and conditioned medium of OvMSCs on the malignant phenotype of SKOV3 ovarian cancer cells were tested, and the status of STAT3 and ERK phosphorylation was investigated. OvMSCs had similar surface marker profiles as bone marrow mesenchymal stem cells, i.e., CD44 (+), CD90 (+) and CD45 (-), and was readily inducible to osteogenic, adipogenic and chondrogenic differentiation. OvMSCs secreted an extremely high level (>2500 pg/ml) of IL-6. Treatment of SKOV3 cells with conditioned media from OvMSCs increased cell proliferation, tumor sphere formation and anchorage independent growth, and resulted in activation of STAT3 but not ERK. Coinjection of OvMSCs with SKOV3 cell enhanced tumorigenesis in NOD-SCID mice. All of these behaviors were blocked by IL-6 receptor blocking antibody administered in vitro or in vivo. The OvMSCs alone injected into mice had no tumor growth after 3 months. By secreting high levels of IL-6, OvMSCs enhance the proliferation, sphere and colony formation and tumorigenesis of SKOV3 cells.

Small putative NANOG, SOX2, and SSEA-4-positive stem cells resembling very small embryonic-like stem cells in sections of ovarian tissue in patients with ovarian cancer

BACKGROUND

In previous studies it has been found that in cell cultures of human adult ovaries there is a population of small stem cells with diameters of 2-4 μm, which are present mainly in the ovarian surface epithelium and are comparable to very small embryonic-like stem cells (VSELs) from bone marrow. These cells are not observed by histopathologists in the ovarian tissue due to their small size and unknown clinical significance. Because these cells express a degree of pluripotency, they might be involved in the manifestation of ovarian cancer. Therefore we studied the ovarian tissue sections in women with borderline ovarian cancer and serous ovarian carcinoma to perhaps identify the small putative stem cells in situ.

METHODS

In 27 women with borderline ovarian cancer and 20 women with high-grade serous ovarian carcinoma the ovarian tissue sections were stained, per standard practice, with eosin and hematoxylin staining and on NANOG, SSEA-4 and SOX2 markers, related to pluripotency, using immunohistochemistry. We focused on the presence and localization of small putative stem cells with diameters of up to 5 μm and with the nuclei spread over nearly the full cell volume.

RESULTS

In ovarian sections of both borderline ovarian cancer and serous ovarian carcinoma patients we were able to identify the presence of small round cells complying with the above criteria. Some of these small cells were NANOG-positive, were located among epithelial cells in the ovarian surface epithelium and as a single cell or groups of cells/clusters in typical "chambers", were found only in the presence of ovarian cancer and not in healthy ovaries and are comparable to those in fetal ovaries. We envision that these small cells could be related to NANOG-positive tumor-like structures and oocyte-like cells in similar "chambers" found in sections of cancerous ovaries, which could support their stemness and pluripotency. Further immunohistochemistry revealed a similar population of SSEA-4 and SOX2-positive cells.

CONCLUSIONS

We may conclude that putative small stem cells expressing markers, related to pluripotency, are present in the ovarian tissue sections of women with borderline ovarian cancer and high-grade serous ovarian carcinoma thus indicating their potential involvement in ovarian cancer.

Are Early Relapses in Advanced-Stage Ovarian Cancer Doomed to a Poor Prognosis?

Objective

Early recurrence (ER) after completion of therapeutic regimen in advanced-stage ovarian cancer is a challenging clinical situation. Patients are perceived as invariably having a poor prognosis. We investigated the possibility of defining different prognostic subgroups and the parameters implicated in prognosis of ER patients.

Study Design

We analyzed a multi-centric database of 527 FIGO stage IIIC and IV ovarian cancer patients. We defined patients relapsing within 12 months as ER and investigated using Cox logistic regression the prognostic factors in ER group. We subsequently divided ER patients into good and poor prognosis groups according to a lower or higher overall survival (OS) at 12 months after relapse and determined parameters associated to poor prognosis.

Results

The median follow up was 49 months. One hundred and thirty eight patients recurred within 12 months. OS and Disease Free Survival (DFS) were 24.6 and 8.6 months, respectively, in this group of patients. Among the ER patients, 73 had a poor prognosis with an OS after relapse below 12 months (mean OS = 5.2 months) and 65 survived after one year (mean OS = 26.9 months). Residual disease (RD) after debulking surgery and mucinous histological subtype negatively impacted prognosis (HR = 1.758, p = 0.017 and HR = 8.641, p = 0.001 respectively). The relative risk of death within 12 months following relapse in ER patients was 1.61 according to RD status. However, RD did not affect DFS (HR = 0.889, p = 0.5).

Conclusion

ER in advanced-stage ovarian cancer does not inevitably portend a short-term poor prognosis. RD status after initial cytoreduction strongly modulates OS, that gives additional support to the concept of maximum surgical effort even in patients who will experience early recurrence. The heterogeneity in outcomes within the ER group suggests a role for tumor biology in addition to classical clinical parameters.

Studying platinum sensitivity and resistance in high-grade serous ovarian cancer: Different models for different questions

High-grade serous ovarian cancer (HGSOC) has the highest mortality rate among all gynecological cancers. Patients are generally diagnosed in an advanced stage with the majority of cases displaying platinum resistant relapses. Recent genomic interrogation of large numbers of HGSOC patient samples indicated high complexity in terms of genetic aberrations, intra- and intertumor heterogeneity and underscored their lack of targetable oncogenic mutations. Sub-classifications of HGSOC based on expression profiles, termed 'differentiated', 'immunoreactive', 'mesenchymal' and 'proliferative', were shown to have prognostic value. In addition, in almost half of all HGSOC patients, a deficiency in homologous recombination (HR) was found that potentially can be targeted using PARP inhibitors. Developing precision medicine requires advanced experimental models. In the current review, we discuss experimental HGSOC models in which resistance to platinum therapy and the use of novel therapeutics can be carefully studied. Panels of better-defined primary cell lines need to be established to capture the full spectrum of HGSOC subtypes. Further refinement of cell lines is obtained with a 3-dimensional culture model mimicking the tumor microenvironment. Alternatively, ex vivo ovarian tumor tissue slices are used. For in vivo studies, larger panels of ovarian cancer patient-derived xenografts (PDXs) are being established, encompassing all expression subtypes. Ovarian cancer PDXs grossly retain tumor heterogeneity and clinical response to platinum therapy is preserved. PDXs are currently used in drug screens and as avatars for patient response. The role of the immune system in tumor responses can be assessed using humanized PDXs and immunocompetent genetically engineered mouse models. Dynamic tracking of genetic alterations in PDXs as well as patients during treatment and after relapse is feasible by sequencing circulating cell-free tumor DNA and analyzing circulating tumor cells. We discuss how various models and methods can be combined to delineate the molecular mechanisms underlying platinum resistance and to select HGSOC patients other than BRCA1/2-mutation carriers that could potentially benefit from the synthetic lethality of PARP inhibitors. This integrated approach is a first step to improve therapy outcomes in specific subgroups of HGSOC patients.

HOTAIR and its surrogate DNA methylation signature indicate carboplatin resistance in ovarian cancer

BACKGROUND

Understanding carboplatin resistance in ovarian cancer is critical for the improvement of patients' lives. Multipotent mesenchymal stem cells or an aggravated epithelial to mesenchymal transition phenotype of a cancer are integrally involved in pathways conferring chemo-resistance. Long non-coding RNA HOTAIR (HOX transcript antisense intergenic RNA) is involved in mesenchymal stem cell fate and cancer biology.

METHODS

We analyzed HOTAIR expression and associated surrogate DNA methylation (DNAme) in 134 primary ovarian cancer cases (63 received carboplatin, 55 received cisplatin and 16 no chemotherapy). We validated our findings by HOTAIR expression and DNAme analysis in a multicentre setting of five additional sets, encompassing 946 ovarian cancers. Chemo-sensitivity has been assessed in cell culture experiments.

RESULTS

HOTAIR expression was significantly associated with poor survival in carboplatin-treated patients with adjusted hazard ratios for death of 3.64 (95 % confidence interval [CI] 1.78-7.42; P < 0.001) in the discovery and 1.63 (95 % CI 1.04-2.56; P = 0.032) in the validation set. This effect was not seen in patients who did not receive carboplatin (0.97 [95 % CI 0.52-1.80; P = 0.932]). HOTAIR expression or its surrogate DNAme signature predicted poor outcome in all additional sets of carboplatin-treated ovarian cancer patients while HOTAIR expressors responded preferentially to cisplatin (multivariate interaction P = 0.008).

CONCLUSIONS

Non-coding RNA HOTAIR or its more stable DNAme surrogate may indicate the presence of a subset of cells which confer resistance to carboplatin and can serve as (1) a marker to personalise treatment and (2) a novel target to overcome carboplatin resistance.

Long-term primary culture of a clear cell ovarian carcinoma reveals an epithelial-mesenchymal cooperative interaction

Background

We studied a primary culture developed from a biopsy of a clear cell carcinoma of the ovary (O-CCC) by (a) assessing its capacity to retain in vitro pathological features of the tumor of origin; (b) characterizing the main cells released from the complex mass without forced purification of any particular cellular entity; and (c) investigating its long-term proliferative capacity.

Methods

A primary cell culture was developed from a pelvic mass diagnosed as an O-CCC. The morphological analysis of the cell culture was carried out by phase contrast microscopy. Markers of epithelial, mesenchymal, and tumor initiating cells were evaluated by immunocytochemistry. Cell proliferation was studied by detection of bromodeoxyuridine (BrdU) incorporated into newly synthesized DNA. As a biomarker of O-CCC, we assessed the expression of hepatocyte nuclear factor (HNF) 1β.

Results

We show that cells with epithelial morphological features express E-cadherin and expand with time in culture, a fact that the incorporation of BrdU confirms. Cells with mesenchymal-like characteristics that express the mesenchymal marker vimentin, however, allocate to the edges of the epithelial compartment. Moreover, we found that some cells with epithelial features also expressed vimentin. At the beginning of incubation, over 60 % of primary cells expressed the O-CCC marker HNF1β; such percentage declined upon passaging. We show that epithelial not mesenchymal cells undergo DNA replication, and that few cells in both epithelial and mesenchymal compartments express the stem-like tumor antigen CD133.

Conclusions

We provide proof-of-principle that cells separated in bulk from a biopsy of an O-CCC can be maintained in culture for several months, and that two consistent cellular compartments—one epithelial that retains the O-CCC marker HNF1β, and another mesenchymal—persist, and seem to have a cooperative interaction leading to the multiplication of epithelial cells within a mesenchymal cellular environment.

Epithelial to Mesenchymal Transition in a Clinical Perspective

Tumor growth and metastatic dissemination rely on cellular plasticity. Among the different phenotypes acquired by cancer cells, epithelial to mesenchymal transition (EMT) has been extensively illustrated. Indeed, this transition allows an epithelial polarized cell to acquire a more mesenchymal phenotype with increased mobility and invasiveness. The role of EMT is quite clear during developmental stage. In the neoplastic context in many tumors EMT has been associated with a more aggressive tumor phenotype including local invasion and distant metastasis. EMT allows the cell to invade surrounding tissues and survive in the general circulation and through a stem cell phenotype grown in the host organ. The molecular pathways underlying EMT have also been clearly defined and their description is beyond the scope of this review. Here we will summarize and analyze the attempts made to block EMT in the therapeutic context. Indeed, till today, most of the studies are made in animal models. Few clinical trials are ongoing with no obvious benefits of EMT inhibitors yet. We point out the limitations of EMT targeting such tumor heterogeneity or the dynamics of EMT during disease progression.

Priming hMSCs with a putative anti-cancer compound, myrtucommulone-a: a way to harness hMSC cytokine expression via modulating PI3K/Akt pathway?

Tumour microenvironment is a key factor for cancer growth and metastasis. Tumour surrounding tissue is known to include high number of mesenchymal stem cells which have been thought to have a role in regulating cancer cell behaviour via paracrine signalling. Therefore, modulating human mesenchymal stem cell (hMSC) secretome is highly significant for controlling and treating disease. Since common therapeutic agents are known to enhance cancer resistance, there is a strong urge to define novel agents for developing cell-based therapies. In the present study, we aimed at investigating the effect of active compounds, myrtucommulone-A (MC-A) and thymoquinone (TQ), on hMSC cytokine expression. Our data revealed that MC-A treatment have significantly altered cytokine expression in hMSCs. Upon MC-A treatment, hMSCs decreased the expression levels of various cytokines including TNF-α, VEGF, IL-6, IL-8 and FGF-2. hMSC conditioned medium (CM) primed with MC-A decreased the proliferation, migration ability and clonogenicity of bladder cancer cells and breast cancer cells in comparison to non-primed hMSC medium and hMSC medium primed with TQ. To the best of our knowledge, this study is the first report showing the effects of active compounds, MC-A and TQ, on hMSCs and therefore valuable for highlighting the potential use of active compounds in combination with hMSCs for cell-based targeted cancer therapy.

Role of mesenchymal stem cells in osteosarcoma and metabolic reprogramming of tumor cells

The tumor microenvironment plays an important role in cancer progression. Here, we focused on the role of reactive mesenchymal stem cells (MSC) in osteosarcoma (OS), and used human adipose MSC and a panel of OS cell lines (Saos-2, HOS, and 143B) to investigate the mutual effect of normal-cancer cell metabolic programming. Our results showed that MSC are driven by oxidative stress induced by OS cells to undergo Warburg metabolism, with increased lactate production. Therefore, we analyzed the expression of lactate monocarboxylate transporters. By real time PCR and immunofluorescence, in MSC we detected the expression of MCT-4, the transporter for lactate efflux, whereas MCT-1, responsible for lactate uptake, was expressed in OS cells. In agreement, silencing of MCT-1 by siRNA significantly affected the ATP production in OS cancer cells. Thus, cancer cells directly increase their mitochondrial biogenesis using this energy-rich metabolite that is abundantly provided by MSC as an effect of the altered microenvironmental conditions induced by OS cells. We also showed that lactate produced by MSC promotes the migratory ability of OS cells. These data provide novel information to be exploited for cancer therapies targeting the mutual metabolic reprogramming of cancer cells and their stroma.

Multiple myeloma as a model for the role of bone marrow niches in the control of angiogenesis

Bone marrow (BM) contains hematopoietic stem cells (HSCs) and nonhematopoietic cells. HSCs give rise to all types of mature blood cells, while the nonhematopoietic component includes osteoblasts/osteoclasts, endothelial cells (ECs), endothelial progenitor cells (EPCs), and mesenchymal stem cells (MSCs). These cells form specialized "niches" which are close to the vasculature ("vascular niche") or to the endosteum ("osteoblast niche"). The "vascular niche", rich in blood vessels where ECs and mural cells (pericytes and smooth muscle cells), create a microenvironment affecting the behavior of several stem and progenitor cells. The vessel wall acts as an independent niche for the recruitment of EPCs and MSCs. This chapter will focus on the description of the role of BM niches in the control of angiogenesis occurring during multiple myeloma progression.

Role of mesenchymal cells in the natural history of ovarian cancer: a review

Background

Ovarian cancer is the deadliest gynaecologic malignancy. Despite progresses in chemotherapy and ultra-radical surgeries, this locally metastatic disease presents a high rate of local recurrence advocating for the role of a peritoneal niche. For several years, it was believed that tumor initiation, progression and metastasis were merely due to the changes in the neoplastic cell population and the adjacent non-neoplastic tissues were regarded as bystanders. The importance of the tumor microenvironment and its cellular component emerged from studies on the histopathological sequence of changes at the interface between putative tumor cells and the surrounding non-neoplastic tissues during carcinogenesis.

Method

In this review we aimed to describe the pro-tumoral crosstalk between ovarian cancer and mesenchymal stem cells. A PubMed search was performed for articles published pertaining to mesenchymal stem cells and specific to ovarian cancer.

Results

Mesenchymal stem cells participate to an elaborate crosstalk through direct and paracrine interaction with ovarian cancer cells. They play a role at different stages of the disease: survival and peritoneal infiltration at early stage, proliferation in distant sites, chemoresistance and recurrence at later stage.

Conclusion

The dialogue between ovarian and mesenchymal stem cells induces the constitution of a pro-tumoral mesencrine niche. Understanding the dynamics of such interaction in a clinical setting might propose new therapeutic strategies.

Mesenchymal cell interaction with ovarian cancer cells induces a background dependent pro-metastatic transcriptomic profile

BACKGROUND

The cross talk between the stroma and cancer cells plays a major role in phenotypic modulation. During peritoneal carcinomatosis ovarian cancer cells interact with mesenchymal stem cells (MSC) resulting in increased metastatic ability. Understanding the transcriptomic changes underlying the phenotypic modulation will allow identification of key genes to target. However in the context of personalized medicine we must consider inter and intra tumoral heterogeneity. In this study we used a pathway-based approach to illustrate the role of cell line background in transcriptomic modification during a cross talk with MSC.

METHODS

We used two ovarian cancer cell lines as a surrogate for different ovarian cancer subtypes: OVCAR3 for an epithelial and SKOV3 for a mesenchymal subtype. We co-cultured them with MSCs. Genome wide gene expression was determined after cell sorting. Ingenuity pathway analysis was used to decipher the cell specific transcriptomic changes related to different pro-metastatic traits (Adherence, migration, invasion, proliferation and chemoresistance).

RESULTS

We demonstrate that co-culture of ovarian cancer cells in direct cellular contact with MSCs induces broad transcriptomic changes related to enhance metastatic ability. Genes related to cellular adhesion, invasion, migration, proliferation and chemoresistance were enriched under these experimental conditions. Network analysis of differentially expressed genes clearly shows a cell type specific pattern.

CONCLUSION

The contact with the mesenchymal niche increase metastatic initiation and expansion through cancer cells' transcriptome modification dependent of the cellular subtype. Personalized medicine strategy might benefit from network analysis revealing the subtype specific nodes to target to disrupt acquired pro-metastatic profile.

Human omental-derived adipose stem cells increase ovarian cancer proliferation, migration, and chemoresistance

Objectives

Adipose tissue contains a population of multipotent adipose stem cells (ASCs) that form tumor stroma and can promote tumor progression. Given the high rate of ovarian cancer metastasis to the omental adipose, we hypothesized that omental-derived ASC may contribute to ovarian cancer growth and dissemination.

Materials and Methods

We isolated ASCs from the omentum of three patients with ovarian cancer, with (O-ASC4, O-ASC5) and without (O-ASC1) omental metastasis. BM-MSCs, SQ-ASCs, O-ASCs were characterized with gene expression arrays and metabolic analysis. Stromal cells effects on ovarian cancer cells proliferation, chemoresistance and radiation resistance was evaluated using co-culture assays with luciferase-labeled human ovarian cancer cell lines. Transwell migration assays were performed with conditioned media from O-ASCs and control cell lines. SKOV3 cells were intraperitionally injected with or without O-ASC1 to track in-vivo engraftment.

Results

O-ASCs significantly promoted invitro proliferation, migration chemotherapy and radiation response of ovarian cancer cell lines. O-ASC4 had more marked effects on migration and chemotherapy response on OVCA 429 and OVCA 433 cells than O-ASC1. Analysis of microarray data revealed that O-ASC4 and O-ASC5 have similar gene expression profiles, in contrast to O-ASC1, which was more similar to BM-MSCs and subcutaneous ASCs in hierarchical clustering. Human O-ASCs were detected in the stroma of human ovarian cancer murine xenografts but not uninvolved ovaries.

Conclusions

ASCs derived from the human omentum can promote ovarian cancer proliferation, migration, chemoresistance and radiation resistance in-vitro. Furthermore, clinical O-ASCs isolates demonstrate heterogenous effects on ovarian cancer in-vitro.

Tumor microenvironment: bone marrow-mesenchymal stem cells as key players

Tumor progression is a multistep phenomenon in which tumor-associated stromal cells perform an intricate cross-talk with tumor cells, supplying appropriate signals that may promote tumor aggressiveness. Among several cell types that constitute the tumor stroma, the discovery that bone marrow-derived mesenchymal stem cells (BM-MSC) have a strong tropism for tumors has achieved notoriety in recent years. Not only are the BM-MSC recruited, but they can also engraft at tumor sites and transdifferentiate into cells such as activated fibroblasts, perivascular cells and macrophages, which will perform a key role in tumor progression. Whether the BM-MSC and their derived cells promote or suppress the tumor progression is a controversial issue. Recently, it has been proposed that proinflammatory stimuli can be decisive in driving BM-MSC polarization into cells with either tumor-supportive or tumor-repressive phenotypes (MSC1/MSC2). These considerations are extremely important both to an understanding of tumor biology and to the putative use of BM-MSC as "magic bullets" against tumors. In this review, we discuss the role of BM-MSC in many steps in tumor progression, focusing on the factors that attract BM-MSC to tumors, BM-MSC differentiation ability, the role of BM-MSC in tumor support or inhibition, the immunomodulation promoted by BM-MSC and metastatic niche formation by these cells.

Emerging role of cancer stem cells in the biology and treatment of ovarian cancer: basic knowledge and therapeutic possibilities for an innovative approach

In 2013 there will be an estimated 22,240 new diagnoses and 14,030 deaths from ovarian cancer in the United States. Despite the improved surgical approach and the novel active drugs that are available today in clinical practice, about 80% of women presenting with late-stage disease have a 5-year survival rate of only 30%. In the last years a growing scientific knowledge about the molecular pathways involved in ovarian carcinogenesis has led to the discovery and evaluation of several novel molecular targeted agents, with the aim to test alternative models of treatment in order to overcome the clinical problem of resistance. Cancer stem cells tend to be more resistant to chemotherapeutic agents and radiation than more differentiated cellular subtypes from the same tissue. In this context the study of ovarian cancer stem cells is taking on an increasingly important strategic role, mostly for the potential therapeutic application in the next future. In our review, we focused our attention on the molecular characteristics of epithelial ovarian cancer stem cells, in particular on possible targets to hit with targeted therapies.

The Necessity of a Systematic Approach for the Use of MSCs in the Clinical Setting

Cell therapy has emerged as a potential therapeutic strategy in regenerative disease. Among different cell types, mesenchymal stem/stromal cells have been wildly studied in vitro, in vivo in animal models and even used in clinical trials. However, while clinical applications continue to increase markedly, the understanding of their physiological properties and interactions raises many questions and drives the necessity of more caution and supervised strategy in their use.

Mesenchymal stem cells in the tumor microenvironment

Mesenchymal stem cells (MSCs) are non-hematopoietic, multipotent cells, which are able to differentiate to bone, adipose and cartilage tissue. MSCs have the characteristic of migration to injured areas or tumor microenvironment following induction by chemokines or inflammatory factors. An increasing number of studies have reported that MSCs recruited to the tumor microenvironment play various roles in tumor cell development and tumor progression. In this study, we reviewed the studies related to the tumor-promoting roles of MSCs from several aspects, such as increasing stemness of tumor cells, mediating migration, promoting angiogenesis, suppressing immune response and inducing drug resistance.

The uncertain role of unmodified mesenchymal stem cells in tumor progression: what master switch?

Mesenchymal stem cells (MSCs) are emerging as promising gene vectors for cancer therapy because of their unique characteristics, including the ease of their expansion and genetic modification and their remarkable tumor-tropic properties. However, there remains a concern that MSCs may promote cancer progression. Surprisingly, there are conflicting reports within the literature describing both the promotion and inhibition of cancer progression by MSCs. The reasons for this discrepancy are still unknown. The surface markers, differentiation ability, and tumorigenic roles of MSCs, as well as their effect on immunoregulation, produce heterogeneity. In this review, we describe the heterogeneity of MSCs by the species from which they are derived, the methodology for their isolation and the context of their interactions with cancer cells. The conflicting roles of MSCs in tumor progression may be attributable to the bimodal effect of unmodified MSCs on immunoregulation. MSCs have been reported to suppress T-cell function and inhibit graft-versus-host disease (GVHD). On the other hand, MSCs elicit the graft-versus-tumor (GVT) effect in some cases. Selective allodepletion may be used to dissociate GVHD from the GVT effect. Understanding the conditions that balance GVHD and the GVT effect of MSCs may be crucial to advance cancer therapy research with respect to MSCs.

Mesenchymal stem cells enhance ovarian cancer cell infiltration through IL6 secretion in an amniochorionic membrane based 3D model

BACKGROUND

The early peritoneal invasion of epithelial ovarian cancer (EOC) by tumoral aggregates presents in ascites is a major concern. The role of the microenvironment seems to be important in this process but the lack of adequate models to study cellular interactions between cancer cells and stromal cells does not allow to uncover the molecular pathways involved. Our goal was to study the interactions between ovarian cancer cells (OCC) and mesenchymal stem cells (MSC) using a 3D model.

METHODS

We used millimetric pieces of amniochorionic membrane - referred to as amniotic membrane scaffold (AMS) - to create 3D peritoneal nodules mimicking EOC early invasion. We were able to measure the distribution and the depth of infiltration using confocal microsopy. We extracted MSC from the amniochorionic membrane using the markers CD34-, CD45-, CD73+, CD90+, CD105+ and CD29+ at the Fluorescence Activated Cell Sorting (FACS) analysis. We used transwell and wound healing tests to test OCC migration and invasion in vitro.

RESULTS

Here we show that OCC tumors were located in regions rich in MSC (70%). The tumors infiltrated deeper within AMS in regions rich in MSC (p<0.001). In vitro tests revealed that higher IL6 secretion in a context of MSC-OCC co-culture could enhance migration and invasion of OCC. After IL6 receptor antagonism, OCC infiltration was significantly decreased, mostly in regions rich in MSCs, indicating that recruitment and tridimensional invasion of OCC was dependent of IL6 secretion.

CONCLUSIONS

The use of tridimensional models using AMS could be a useful tool to decipher early molecular events in ovarian cancer metastasis. Cytokine inhibitors interrupting the cross-talk between OCCs and MSCs such as IL6 should be investigated as a new therapeutic approach in ovarian cancer.

Ovarian cancer stem cells: a new target for cancer therapy

Ovarian cancer is a highly lethal disease among all gynecologic malignancies and is the fifth leading cause of cancer-related death in women. Although the standard combination of surgery and chemotherapy was initially effective in patients with ovarian cancer, disease relapse commonly occurred due to the generation of chemoresistance. It has been reported that cancer stem cells (CSCs) are involved in drug resistance and cancer recurrence. Over the past decades, increasing studies have been done to identify CSCs from human ovarian cancer cells. The present paper will summarize different investigations on ovarian CSCs, including isolation, mechanisms of chemoresistance, and therapeutic approaches. Although there are still numerous challenges to translate basic research to clinical applications, understanding the molecular details of CSCs is essential for developing effective strategies to prevent ovarian cancer and its recurrence.

Role of the microenvironment in ovarian cancer stem cell maintenance

Despite recent progresses in cancer therapy and increased knowledge in cancer biology, ovarian cancer remains a challenging condition. Among the latest concepts developed in cancer biology, cancer stem cells and the role of microenvironment in tumor progression seem to be related. Indeed, cancer stem cells have been described in several solid tumors including ovarian cancers. These particular cells have the ability to self-renew and reconstitute a heterogeneous tumor. They are characterized by specific surface markers and display resistance to therapeutic regimens. During development, specific molecular cues from the tumor microenvironment can play a role in maintaining and expanding stemness of cancer cells. The tumor stroma contains several compartments: cellular component, cytokine network, and extracellular matrix. These different compartments interact to form a permissive niche for the cancer stem cells. Understanding the molecular cues underlying this crosstalk will allow the design of new therapeutic regimens targeting the niche. In this paper, we will discuss the mechanisms implicated in the interaction between ovarian cancer stem cells and their microenvironment.