Primary culture and mRNA analysis of human ovarian cells

Luteolin directly binds to KDM4C and attenuates ovarian cancer stemness via epigenetic suppression of PPP2CA/YAP axis

Long-term use of low-toxic natural products holds the promise for eradicating cancer stem cells. In this study, we report that luteolin, a natural flavonoid, attenuates the stemness of ovarian cancer stem cells (OCSCs) by directly binding to KDM4C and epigenetic suppression of PPP2CA/YAP axis. Ovarian cancer stem like cells (OCSLCs) isolated by suspension culture and CD133 + ALDH+ cell sorting was employed as OCSCs model. The maximal non-toxic dose of luteolin suppressed stemness properties, including sphere-forming capacity, the expression of OCSCs markers, sphere-initiating and tumor-initiating capacities, as well as the percentage of CD133 + ALDH+ cells of OCSLCs. Mechanistic study showed that luteolin directly binds to KDM4C, blocks KDM4C-induced histone demethylation of PPP2CA promoter, inhibits PPP2CA transcription and PPP2CA-mediated YAP dephosphorylation, thereby attenuating YAP activity and the stemness of OCSLCs. Furthermore, luteolin sensitized OCSLCs to traditional chemotherapeutic drugs in vitro and in vivo. In summary, our work revealed the direct target of luteolin and the underlying mechanism of the inhibitory effect of luteolin on the stemness of OCSCs. This finding thus suggests a novel therapeutic strategy for eradicating human OCSCs driven by KDM4C.

Does the ovarian surface epithelium differentiate into primordial follicle and primary follicle precursor structures?

Purpose: The aim of this study is to investigate the differentiation capacity of ovarian surface epithelial cells both in cell culture conditions and in ovarian tissue sections. Materials and Methods: The ovaries of two prepubertal (4 weeks old) female rats were divided into small pieces and explant cell culture was created. Ovarian surface epithelium proliferating together with ovarian stromal cells in mixed cell culture was isolated and reproduced. In addition, ovarian surface epithelium was examined in histological sections of ovarian tissue and images were taken under the microscope. Results: The morphological appearance of the ovarian surface epithelium was found to be cobblestone. In the count performed under phase contrast microscopy, it was observed that 2x106 and 3x106 cells were grown in the culture dishes, respectively. Primordial follicle-like structures were observed in some areas of the petri dishes. On the histological sections, primordial and primary follicle precursor structures were observed on the basement membrane. Conclusion: Showing oocyte markers (Gdf-9, C-Mos, Zpc, Stella) and germ cell markers (Dazl, Vasa, Blimp1, Fragilis) both in cell cultures and in histological sections can give us valuable information in terms of monitoring the differentiation capacity of these cells.

Use of Liquid Patient Ascites Fluids as a Preclinical Model for Oncolytic Virus Activity

The translational success of oncolytic virotherapies would benefit from the widespread use of clinically relevant ex vivo models. Malignant ascites, an accumulation of fluid in the peritoneum due to disseminated cancer, recapitulates many features of the tumor microenvironment, making it a valuable model for studying oncolytic virus activity. Here, we describe a method for the separation and storage of cellular and acellular components of malignant ascites, followed by flow cytometric characterization of the cellular fraction. We then outline a simple experiment using whole ascites to assess the activity of a bispecific T cell engager (BiTE)-expressing oncolytic adenovirus.

Isolation and phenotypic characterization of tumor cells of patients with a diagnosis of ovarian cancer

Ovarian cancer is the fifth leading cause of cancer‐related deaths. It causes approximately 125,000 deaths per year worldwide; its diagnosis is made in advanced stages resulting in a high mortality rate. The objective of the study was optimizing the isolation of cells obtained from the solid tumor and ascitic fluid of patients with ovarian cancer and the phenotype with markers related to the epithelial–mesenchymal transition. For this, the solid tumor tissue was disaggregated and cultivated with different methodologies. As a result, cell growth was obtained and epi‐immunofluorescence was performed using antibodies against E‐cadherin, EpCAM, N‐cadherin, vimentin, CD133, and CD44. The primary culture from the solid tumor was obtained using Dispase II and DMEM/F12. Finally, heterogeneity was detected in terms of the expression of mesenchymal and epithelial type markers in the two types of isolated cells. Additionally, CD133 and CD44 expression was detected, proteins associated with the tumor stem cells phenotype.

Role of Survivin and p53 Expression in Response of Primary Culture of Ovarian Cancer Cells to Treatment With Chemotherapeutic Agents

BACKGROUND

Ovarian cancer is associated with a high relapse rate and is the fifth leading cause of cancer deaths in women. The genetic profile of a tumor is responsible for deciding response to chemotherapeutic agents. In this study, we investigate the relation between survivin and p53 expression and response to chemotherapeutic agents of primary cultures of ovarian cancer cells established from ascitic fluid.

MATERIALS AND METHOD

Ascitic fluid and Dulbecco's modified Eagle medium was mixed in equal proportion in culture flasks and incubated to establish primary culture. The cells were treated with different combinations of carboplatin and paclitaxel with and without survivin small interfering RNA transfection. Cell survival was estimated by MTT assay. Survivin and p53 expression was quantified by real-time polymerase chain reaction.

RESULTS

Out of 19 ascitic fluid samples, 13 primary cultures of ovarian cancer cells were established. The half maximal inhibitory concentration doses of carboplatin (≥70 μg/mL) and paclitaxel (≥18 μg/mL) were high for 10/13 and 5/13 patients, respectively. Survivin messenger RNA expression was significantly downregulated on treatment with carboplatin (100 μg/mL), paclitaxel (12.5 μg/mL), and a combination of carboplatin (50 μg/mL) and paclitaxel (6.25 μg/mL). Only paclitaxel-treated ovarian cancer cells showed decrease in expression of p53. Survivin small interfering RNA increased sensitivity of the primary cultures to chemotherapeutic agents.

CONCLUSIONS

The present study highlights the fact that establishing primary cultures from ascitic fluid may help to develop personalized treatment regime for individual patients based on their molecular profile. Our study also shows that supplementing taxols drugs with survivin inhibitors may prove to be beneficial in the treatment of ovarian cancer patients.

Establishment of five immortalized human ovarian surface epithelial cell lines via SV40 T antigen or HPV E6/E7 expression

Background

Human ovarian surface epithelial (HOSE) cells are a critical cell source for ovarian cancer research; however, they are difficult to obtain and maintain under standard laboratory conditions in large quantities. The aim of this study was to generate immortalized HOSE (IHOSE) cells with maintained properties to the original cell source, thereby guaranteeing a sufficiently large cell quantity for ovarian cancer research.

Methods

HOSE cells isolated from four non-cancer patients and five IHOSE cell lines were established by induction of HPV-E6/E7 expression or SV40 large T antigen using a lenti-viral system. Each of IHOSE cells was confirmed to be distinct by STR profiling. RNA-sequencing was used to compare gene expression profiles in HOSE, IHOSE and ovarian cancer cells.

Results

RNA-sequencing results revealed a stronger linear correlation in gene expression between IHOSE and HOSE cells (R² = 0.9288) than between IHOSE or HOSE cells and ovarian cancer cells (R² = 0.8562 and R² = 0.7982, respectively). The gene expression pattern of 319 differentially expressed genes revealed minimal differences between HOSE and IHOSE cells, while a strong difference between ovarian cancer cells and HOSE or IHOSE cells was observed. Furthermore, the five IHOSE cell lines displayed morphological characteristics typical of epithelial cells but showed a lower level of EpCAM, CD133 and E-cadherin, as cancer stem marker, than ovarian cancer cells. Moreover, unlike cancer cells, IHOSE cells could not form colonies in the anchorage-independent soft agar growth assay.

Conclusion

These findings demonstrate that five newly established IHOSE cell lines have characteristics of progenitor HOSE cells while exhibiting continuous growth, and thus, should be highly useful as control cells for ovarian cancer research.

Establishment of Primary Cell Culture From Ascitic Fluid and Solid Tumor Obtained From Epithelial Ovarian Carcinoma Patients

OBJECTIVE

Ovarian cancer is the seventh leading cause of cancer death worldwide. This is mainly due to late diagnosis and high rate of relapse and resistance following chemotherapy. In the present study, we describe simple and cost-effective method to establish primary culture from ascitic fluid and solid tumor obtained from epithelial ovarian carcinoma patient, which may provide a better tool for in vitro testing of drug sensitivity and designing individualized treatment protocol.

METHODS

Complete Dulbecco modified Eagle medium (DMEM) was prepared by supplementing DMEM with 10% fetal bovine serum and antibiotics (ciprofloxacin and amphotericin B). Establishment of primary culture of ovarian cancer cells from ascites fluid and solid tumor was done by using complete DMEM media.

RESULTS

Primary cultures of ovarian cancer cells were established from ascitic fluid and solid tumor tissue. Of the 7 ascitic fluid samples, we were able to establish 5 primary cultures of ovarian cancer cells. All the 7 samples were diagnosed as serous papillary adenocarcinoma. Some fibroblasts were also attached to culture flask on day 4; they were removed by exposing them to trypsin for a brief period. On day 7, grape-like clusters were visualized under inverted microscope. The cells became confluent on the 10th and 11th day and showed cobblestone appearance, which is a hallmark of ovarian cancer cells. Senescent irregularly shaped cells that have ceased dividing were seen after 8 to 10 passages.

CONCLUSION

This study highlights the fact that establishing primary cultures from ascitic fluid or solid tumor tissue may help us to understand the molecular profile of the cancer cells, which allow us to select the best chemotherapeutic agent for ovarian cancer patients and thus take a step toward patient-tailored therapy so that patients are not exposed to drugs to which they are not likely to respond.

Nanochips of Tantalum Oxide Nanodots as artificial-microenvironments for monitoring Ovarian cancer progressiveness

Nanotopography modulates cell characteristics and cell behavior. Nanotopological cues can be exploited to investigate the in-vivo modulation of cell characteristics by the cellular microenvironment. However, the studies explaining the modulation of tumor cell characteristics and identifying the transition step in cancer progressiveness are scarce. Here, we engineered nanochips comprising of Tantalum oxide nanodot arrays of 10, 50, 100 and 200 nm as artificial microenvironments to study the modulation of cancer cell behavior. Clinical samples of different types of Ovarian cancer at different stages were obtained, primary cultures were established and then seeded on different nanochips. Immunofluorescence (IF) was performed to compare the morphologies and cell characteristics. Indices corresponding to cell characteristics were defined. A statistical comparison of the cell characteristics in response to the nanochips was performed. The cells displayed differential growth parameters. Morphology, Viability, focal adhesions, microfilament bundles and cell area were modulated by the nanochips which can be used as a measure to study the cancer progressiveness. The ease of fabrication of nanochips ensures mass-production. The ability of the nanochips to act as artificial microenvironments and modulate cell behavior may lead to further prospects in the markerless monitoring of the progressiveness and ultimately, improving the prognosis of Ovarian cancer.

Evaluation of Effects of Metformin in Primary Ovarian Cancer Cells

BACKGROUND

Ovarian cancer is the third most common cause of cancer in Indian women. Despite an initial 70-80% response rate, most patients relapse within 1-2 years and develop chemoresistance. Hence, identification or repositioning of drugs to resensitise ovarian cancer cells to existing chemotherapy is needed. Traditionally immortalized cell lines have been used in research, but these may contain genetic aberrations and chromosomal abnormalities serving as poor indicators of normal cell phenotype and progression of early-stage disease. The use of primary cells, maintained for only short periods of time in vitro, may serve as the best representative for studying in vivo conditions of the tissues from which they are derived. In this study we have attempted to evaluate the effect of metformin (an antidiabetic drug) in primary ovarian cancer cells because of its promising effect in other solid tumours.

MATERIALS AND METHODS

Primary cultures of epithelial ovarian cancer cells established from ascitic fluid of untreated ovarian cancer patients were used. The cells were treated with metformin at doses standardized by MTT assay and its ability to induce apoptosis was studied. The cells were analysed for apoptosis and apoptosis related proteins by flow cytometry and western blotting respectively.

RESULTS

Metformin induced apoptosis in ovarian cancer cells, provoking cell cycle arrest in the G0/G1 and S phase. It induced apoptosis in ovarian cancer cells by, down-regulating Bcl-2 and up-regulating Bax expression.

CONCLUSIONS

Metformin was able to induce apoptosis in primary ovarian cancer cells by modulating the expression of Bcl-2 family proteins. These data are relevant to ongoing translational research efforts exploring the chemotherapeutic potential of metformin.

Microsatellite instable and microsatellite stable primary endometrial carcinoma cells and their subcutaneous and orthotopic xenografts recapitulate the characteristics of the corresponding primary tumor

OBJECTIVE

Well-characterized, low-passage, primary cell cultures established directly from patient tumors are an important tool for drug screening because these cultures faithfully recapitulate the genomic features of primary tumors. Here, we aimed to establish these cell cultures from primary endometrial carcinomas (ECs) and to develop subcutaneous and orthotopic xenograft models as a model to validate promising treatment options for EC in the in vivo setting.

METHODS

Primary cell cultures of EC tumors were established and validated by analysing histologic and genetic characteristics, telomerase activity, and in vitro and in vivo growth characteristics. Using these primary cell cultures, subcutaneous and orthotopic mouse models were subsequently established.

RESULTS

We established and characterized 7 primary EC cell cultures and corresponding xenograft models of different types of endometrioid tumors. Interestingly, we observed that the chance to successfully establish a primary cell culture seems higher for microsatellite instable than microsatellite stable tumors. For the first time, we also established an orthotopic murine model for EC derived from a primary cell culture. In contrast to EC cell lines, grafted tumor cultures preserved the original tumor structure and mimicked all histologic features. They also established abdominal and distant metastases, reflecting the tumorigenic behavior in the clinical setting. Remarkably, the established cell cultures and xenograft tumors also preserved the genetic characteristics of the primary tumor.

CONCLUSIONS

The established EC cultures reflect the epithelial genetic characteristics of the primary tumor. Therefore, they provide an appropriate model to investigate EC biology and apply high-throughput drug screening experiments. In addition, the established murine xenograft models, in particular the orthotopic model, will be useful to validate promising therapeutic strategies in vivo, as the grafted tumors closely resemble the primary tumors from which they were derived. Microsatellite instable status seems to determine the success rate of establishing primary cell cultures.

miR-634 restores drug sensitivity in resistant ovarian cancer cells by targeting the Ras-MAPK pathway

Background

Drug resistance hampers the efficient treatment of malignancies, including advanced stage ovarian cancer, which has a 5-year survival rate of only 30 %. The molecular processes underlying resistance have been extensively studied, however, not much is known about the involvement of microRNAs.

Methods

Differentially expressed microRNAs between cisplatin sensitive and resistant cancer cell line pairs were determined using microarrays. Mimics were used to study the role of microRNAs in drug sensitivity of ovarian cancer cell lines and patient derived tumor cells. Luciferase reporter constructs were used to establish regulation of target genes by microRNAs.

Results

MiR-634 downregulation was associated with cisplatin resistance. Overexpression of miR-634 affected cell cycle progression and enhanced apoptosis in ovarian cancer cells. miR-634 resensitized resistant ovarian cancer cell lines and patient derived drug resistant tumor cells to cisplatin. Similarly, miR-634 enhanced the response to carboplatin and doxorubicin, but not to paclitaxel. The cell cycle regulator CCND1, and Ras-MAPK pathway components GRB2, ERK2 and RSK2 were directly repressed by miR-634 overexpression. Repression of the Ras-MAPK pathway using a MEK inhibitor phenocopied the miR-634 effects on viability and chemosensitivity.

Conclusion

miR-634 levels determine chemosensitivity in ovarian cancer cells. We identify miR-634 as a therapeutic candidate to resensitize chemotherapy resistant ovarian tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0464-4) contains supplementary material, which is available to authorized users.

Survivin siRNA increases sensitivity of primary cultures of ovarian cancer cells to paclitaxel

PURPOSE

This aim of this study was to use ovarian cancer cells shed in ascitic fluid to establish primary cultures and subsequently use it to detect drug resistance to paclitaxel. Survivin siRNA was used to down regulate survivin expression and effect on paclitaxel resistance was also evaluated.

METHODOLOGY

Ascitic fluid along with corresponding primary tumor tissue was collected from twenty untreated epithelial ovarian cancer patients. Ten primary cultures were established from ascites obtained from untreated ovarian cancer patients in MCDB 105 and M199 medium (ratio 1:1). Knockdown of survivin was done using siRNA and sensitivity to paclitaxel was evaluated by MTT assay.

RESULTS

Grape-like clusters of ovarian cancer cells present in ascites attached and gave a characteristic cobble stone appearance. Treatment with survivin siRNA resulted in a fivefold decrease in survivin expression in primary cultures. Survivin siRNA treatment significantly increased the sensitivity of the primary ovarian cancer cell cultures to paclitaxel.

CONCLUSION

Ascitic cancer cells reflect the molecular profile of tumor and can be used to diagnose resistance to chemotherapy. This study also establishes that high survivin expression is also responsible for resistance to paclitaxel.

Citrate synthase expression affects tumor phenotype and drug resistance in human ovarian carcinoma

Citrate synthase (CS), one of the key enzymes in the tricarboxylic acid (TCA) cycle, catalyzes the reaction between oxaloacetic acid and acetyl coenzyme A to generate citrate. Increased CS has been observed in pancreatic cancer. In this study, we found higher CS expression in malignant ovarian tumors and ovarian cancer cell lines compared to benign ovarian tumors and normal human ovarian surface epithelium, respectively. CS knockdown by RNAi could result in the reduction of cell proliferation, and inhibition of invasion and migration of ovarian cancer cells in vitro. The drug resistance was also inhibited possibly through an excision repair cross complementing 1 (ERCC1)-dependent mechanism. Finally, upon CS knockdown we observed significant increase expression of multiple genes, including ISG15, IRF7, CASP7, and DDX58 in SKOV3 and A2780 cells by microarray analysis and real-time PCR. Taken together, these results suggested that CS might represent a potential therapeutic target for ovarian carcinoma.

Doxorubicin synergizes with 34.5ENVE to enhance antitumor efficacy against metastatic ovarian cancer

PURPOSE

Novel therapeutic regimens are needed to improve dismal outcomes associated with late-stage ovarian cancer. Oncolytic viruses are currently being tested in patients with ovarian cancer. Here, we tested the therapeutic efficacy of combining doxorubicin with 34.5ENVE, an oncolytic herpes simplex virus transcriptionally driven by a modified stem cell-specific nestin promoter, and encoding for antiangiogenic Vasculostatin-120 (VStat120) for use against progressive ovarian cancer.

EXPERIMENTAL DESIGN

Antitumor efficacy of 34.5ENVE was assessed in ovarian cancer cell lines, mouse ascites-derived tumor cells, and primary patient ascites-derived tumor cells by standard MTT assay. The ability of conditioned medium derived from 34.5ENVE-infected ovarian cancer cells to inhibit endothelial cell migration was measured by a Transwell chamber assay. Scope of cytotoxic interactions between 34.5ENVE and doxorubicin were evaluated using Chou-Talalay synergy analysis. Viral replication, herpes simplex virus receptor expression, and apoptosis were evaluated. Efficacy of oncolytic viral therapy in combination with doxorubicin was evaluated in vivo in the murine xenograft model of human ovarian cancer.

RESULTS

Treatment with 34.5ENVE reduced cell viability of ovarian cancer cell lines, and mouse ascites-derived and patient ascites-derived ovarian tumor cells. Conditioned media from tumor cells infected with 34.5ENVE reduced endothelial cell migration. When combined with doxorubicin, 34.5ENVE killed synergistically with a significant increase in caspase-3/7 activation, and an increase in sub-G1 population of cells. The combination of doxorubicin and 34.5ENVE significantly prolonged survival in nude mice bearing intraperitoneal ovarian cancer tumors.

CONCLUSIONS

This study indicates significant antitumor efficacy of 34.5ENVE alone, and in combination with doxorubicin against disseminated peritoneal ovarian cancer.

The use of ovarian cancer cells from patients undergoing surgery to generate primary cultures capable of undergoing functional analysis

The use of cell lines or animal models has significant disadvantages when dealing with a set of heterogeneous diseases such as epithelial ovarian cancer. This has clinical relevance in that biomarkers developed using cell line or animal models are often not transferable to the clinical setting. In this study, we describe the development of a robust protocol for developing primary cultures of ovarian cancer which will overcome some of these difficulties. Women undergoing surgery for ovarian cancer were recruited and samples of ascites and solid tumour deposits were used to develop primary cultures. Cells were characterised using a panel of immunofluorescent antibodies prior to use in a variety of assays including functional assessment of DNA repair pathways. During the four year study period, viable cultures, confirmed to be epithelial in origin were generated from 156 of 172 (91%) cases recruited. Characterisation was carried out using a panel of antibodies including pancytokeratin, CA125, EpCAM, MOC-31, D2-40 and vimentin. Senescence occurred between the 2^nd and 8^th passages in all cultures except one in which spontaneous immortalization occurred. Cells could be successfully cultured even after a period of storage at 4°C and cultured cells were capable of being used for a variety of applications including functional assays. Upon functional assessment there was minimal intra-tumour heterogeneity. It is therefore possible to derive viable ovarian cancer cell cultures in the majority of patients undergoing surgery. Cells cultured directly from patient cancers provide an accurate and highly diverse model.

Epithelial ovarian cancer experimental models

Epithelial ovarian cancer (OvCa) is associated with high mortality and, as the majority (>75%) of women with OvCa have metastatic disease at the time of diagnosis, rates of survival have not changed appreciably over 30 years. A mechanistic understanding of OvCa initiation and progression is hindered by the complexity of genetic and/or environmental initiating events and lack of clarity regarding the cell(s) or tissue(s) of origin. Metastasis of OvCa involves direct extension or exfoliation of cells and cellular aggregates into the peritoneal cavity, survival of matrix-detached cells in a complex ascites fluid phase and subsequent adhesion to the mesothelium lining covering abdominal organs to establish secondary lesions containing host stromal and inflammatory components. Development of experimental models to recapitulate this unique mechanism of metastasis presents a remarkable scientific challenge, and many approaches used to study other solid tumors (for example, lung, colon and breast) are not transferable to OvCa research given the distinct metastasis pattern and unique tumor microenvironment (TME). This review will discuss recent progress in the development and refinement of experimental models to study OvCa. Novel cellular, three-dimensional organotypic, and ex vivo models are considered and the current in vivo models summarized. The review critically evaluates currently available genetic mouse models of OvCa, the emergence of xenopatients and the utility of the hen model to study OvCa prevention, tumorigenesis, metastasis and chemoresistance. As these new approaches more accurately recapitulate the complex TME, it is predicted that new opportunities for enhanced understanding of disease progression, metastasis and therapeutic response will emerge.

Establishment, characterization and downstream application of primary ovarian cancer cells derived from solid tumors

Ovarian cancer is the deadliest of the gynecological diseases and the fifth cause of cancer death among American women. This is mainly due to the lack of prognostic tools capable of detecting early stages of ovarian cancer and to the high rate of resistance to the current chemotherapeutic regimens. In this scenario the overall 5-year survival rate for ovarian cancer patients diagnosed at late stage is less than 25%. Abnormalities associated with the malignant phenotype and the mechanisms of tumor progression are not clearly understood. In vitro studies are necessary, yet have been hampered due to the limitations accompanied with the use of ovarian cancer cell lines and the heterogeneity of the ovarian cancer cell population derived from ascites fluids. In this study we present a simple, rapid and reproducible method for the isolation and characterization of ovarian cancer cells from solid tumor tissue and show that enzymatic digestion for 30 minutes with dispase II results in the most effective recovery of viable epithelial ovarian cancer (EOC) cells. The resulting cancer (EOC) cell preparations demonstrate a significant yield, high levels of viability and are fibroblast-free. They grow for up to six passages and retain the capacity of forming spheroids-like structures in agarose. In addition, they can be genetically manipulated and used for drug screening, thus rendering them highly suitable for downstream applications. Notably, isolation of ovarian cancer cells from solid specimens using this method has the advantage of allowing for isolation of cancer cells from early stages of ovarian cancer as well as obtaining cells from defined either primary and/or metastatic ovarian cancer sites. Thus, these cells are highly suitable for investigations aimed at understanding ovarian cancer.

Role of cell surface molecules and autologous ascitic fluid in determining efficiency of adenoviral transduction of ovarian cancer cells

Adenovirus is the most frequently used virus in gene therapy clinical trials. There have been conflicting reports on the ability of adenovirus to transduce primary ovarian cancer samples and the expression of relevant cell surface molecules. These factors were examined using primary ovarian cancer cells cultured from ascites and solid tumor to gain insights into the clinical use of adenovirus in ovarian cancer. The level of transduction of primary cultures was much higher than uncultured cells and established cell lines, and correlated with higher levels of coxsackie-adenovirus receptor (CAR) and integrin expression. Growth of primary cultures in autologous ascitic fluid prevented an increase in CAR expression and inhibited transduction compared with cells treated in supplemented RPMI. Cells at the periphery of solid tumor samples were transduced using a replication-incompetent virus and correlated with CAR expression. However, transduction was abolished by autologous ascitic fluid, despite the expression of CAR. We conclude that the use of adenoviruses for ovarian cancer gene therapy will require testing in the presence of inhibitory factors in ascitic fluid. The clinical use of adenoviral vectors may require circumvention of such inhibitory factors and the use of replication competent adenovirus to enable efficient viral penetration of the cancer.

Development of a functional assay for homologous recombination status in primary cultures of epithelial ovarian tumor and correlation with sensitivity to poly(ADP-ribose) polymerase inhibitors

PURPOSE

Poly(ADP-ribose) polymerase (PARP) inhibitors selectively target homologous recombination (HR)-defective cells and show good clinical activity in hereditary breast and ovarian cancer associated with BRCA1 or BRCA2 mutations. A high proportion (up to 50%) of sporadic epithelial ovarian cancers (EOC) could be deficient in HR due to genetic or epigenetic inactivation of BRCA1/BRCA2 or other HR genes. Therefore, there is a potential for extending the use of PARP inhibitors to these patients if HR status can be identified. We developed a functional assay of HR status in primary cultures of EOCs based on Rad51 focus formation that correlates well with sensitivity to the potent PARP inhibitor AG014699.

EXPERIMENTAL DESIGN

Primary cultures were derived from ascitic fluid from patients with EOCs. HR status was investigated by gammaH2AX and Rad51 focus formation by immunofluorescence. Cytotoxicity to PARP inhibitors was tested by sulforhodamine B and survival assay.

RESULTS

Twenty-five cultures were evaluated for HR status and cytotoxicity to PARP inhibitor. Following exposure to AG014699, there was an increase in Rad51 foci (HR competent) in 9 of 24 (36%) but no increase (HR deficient) in 16 of 24 (64%) cultures. Cytotoxicity was observed in 15 of 16 (93%) HR-deficient samples but not in 9 of 9 HR-competent samples following 24-hour exposure to 10 mumol/L AG014699.

CONCLUSION

HR status can be determined in primary cancer samples by Rad51 focus formation, and this correlates with in vitro response to PARP inhibition. Use of this assay as a biomarker now needs testing in the setting of a clinical trial.

Epithelial-mesenchymal transition of ovarian tumor cells induces an angiogenic monocyte cell population

Vasculogenesis, or recruitment of progenitors able to differentiate into endothelial-like cells, may provide an important contribution to neovessel formation in tumors. However, the factors involved in the vasculogenic process and in particular the role of the epithelial-mesenchymal transition of tumor cells have not yet been investigated. We found a CD14(+)/KDR(+) angiogenic monocyte population in undifferentiated ovarian tumors, significantly increased in the corresponding tumor metastasis. In vitro, monocyte differentiation into CD14(+)/KDR(+) cells was induced by conditioned media from the primary ovarian tumor cells expressing a mesenchymal phenotype. In contrast, the ovarian tumor cell line SKOV3 expressing an epithelial phenotype was unable to stimulate the differentiation of monocytes into CD14(+)/KDR(+) cells. When an epithelial-mesenchymal transition was induced in SKOV3, they acquired this differentiative ability. Moreover, after mesenchymal transition pleiotrophin expression by SKOV3 was increased and conversely its blockade significantly reduced monocyte differentiation. The obtained CD14(+)/KDR(+) cell population showed the expression of endothelial markers, increased the formation of capillary-like structures by endothelial cells and promoted the migration of ovarian tumor cells in vitro. In conclusion, we showed that the epithelial-mesenchymal transition of ovarian tumor cells induced differentiation of monocytes into the pro-angiogenic CD14(+)/KDR(+) population and thus it may provide a tumor microenvironment that favours vasculogenesis and metastatization of the ovarian cancer.

Use of a novel 3D culture model to elucidate the role of mesothelial cells, fibroblasts and extra-cellular matrices on adhesion and invasion of ovarian cancer cells to the omentum

The omentum is a major site of ovarian cancer metastasis. Our goal was to establish a three-dimensional (3D) model of the key components of the omental microenvironment (mesothelial cells, fibroblasts and extracellular matrices) to study ovarian cancer cell adhesion and invasion. The 3D model comprised of primary human fibroblasts extracted from normal human omentum, mixed with ECM and covered by a layer of primary human mesothelial cells, also from normal human omentum. After addition of ovarian cancer cells, the histological appearance of the 3D culture mimicked microscopic metastases to the omentum from patients with ovarian cancer. When ovarian cancer cells, SKOV3ip.1 and HeyA8, were applied to the 3D omental culture, 60% and 68% of all cells attached, respectively, but only 18% and 25% were able to invade. Ovarian cancer cells preferentially adhered to and invaded collagen I, followed by binding to collagen IV, fibronectin, vitronectin, laminin 10 and 1. Omental mesothelial cells significantly inhibited ovarian cancer cell adhesion and invasion, while omental fibroblasts induced adhesion and invasion. This effect is clearly mediated by direct cell-cell contact, since conditioned medium from mesothelial cells or fibroblasts has a minimal, or no, effect on ovarian cancer cell adhesion and invasion. In summary, we have established a 3D model to study the early steps of ovarian cancer metastasis to the human omentum, and found that omental mesothelial cells inhibit, while omental fibroblasts and the ECM enhance, the attachment and invasion of ovarian cancer cells.

Primary culture of ovarian surface epithelial cells and ascites-derived ovarian cancer cells from patients

Our laboratory has refined the technique for isolating primary cultures of normal human ovarian surface epithelial (OSE) cells by combining two different protocols involving the enzymatic and mechanical removal of OSE cells from ovarian biopsies. A simple protocol of obtaining primary epithelial ovarian cancer (EOC) cells from the ascites fluid removed from patients with high-grade ovarian cancer is also described. These methods allow for the direct application of many molecular and cellular analyses of normal versus cancer cells isolated freshly from patients, with the added potential for retrospective analyses of archived cells and tissues. Thus, we have included optional steps for the immediate preparation of ascites-derived EOC cells to be used for subsequent cytological analyses. Initial isolation of OSE or EOC cells can be completed in 1 h, and primary cells are further expanded in culture for several weeks.

Integration of Jacobson's Pellicle Method into Proteomic Strategies for Plasma Membrane Proteins

A modified form of the cationic colloidal silica technique for plasma membrane isolation has been combined with SDS-PAGE, mass spectrometry, and bioinformatics for evaluation as a proteomics strategy with human multiple myeloma cells and human breast cancer cells. On the basis of Western blots, half of the protein isolated is estimated to come from the plasma membrane. Forty-three percent of the 366 proteins identified by mass spectrometry had been previously classified as plasma membrane proteins. Thirty proteins previously categorized as hypothetical membrane proteins are now reported to be expressed.

Cultures of ovarian surface epithelium from women with and without a hereditary predisposition to develop female adnexal carcinoma

AIM

Conflicting evidence exists on whether in vivo morphological characteristics can distinguish Ovarian Surface Epithelium (OSE) of ovaries obtained from women with and without a predisposition to develop female adnexal (ovarian and fallopian tube) carcinoma. This study aims to detect differences in growth potential and morphology that are maintained or specifically expressed in vitro.

STUDY DESIGN

Ovarian surfaces were scraped to retrieve OSE cells from 56 women at hereditary high risk for female adnexal carcinoma, of whom 33 are BRCA1 and four are BRCA2 mutation carriers (Predisposed OSE, POSE) and from 26 women without such risk (Non Predisposed OSE, NPOSE). Number of passages and total cell yield until last passage, as well as morphology was compared between both groups. To confirm morphology, the expression of epithelial, mesothelial, and fibroblast markers was assessed.

RESULTS

Both POSE and NPOSE cultures displayed similar growth potential and morphology. The expression of epithelial markers cyto-keratins 7 and 8 was similar between both groups. Only in cultures in which cells did not uniformly exhibit these markers, the percentage of cells expressing these markers was significantly lower at last passage when compared to the initial culture. In these latter cultures, cells that were morphologically indistinguishable from fibroblasts were observed. Mesothelial marker calretinin was expressed in 75% of cells of both POSE and NPOSE cultures and correlates with cyto-keratins 7 and 8 expression. CA 125 expression was equally low in POSE and NPOSE cultures (4.3%). Fibroblast markers FSM and vimentin were expressed in 100% and collagen IV was expressed in 16% of cells in all cultures.

CONCLUSION

OSE cells derived from women with a hereditary predisposition to develop female adnexal cancer possess similar in vitro characteristics as OSE from women without this predisposition. On basis of our results, it seems advisable to study only 100% cyto-keratins 7 and 8 positive OSE cultures, since contamination of fibroblasts in some primary OSE cultures cannot be ruled out.

Identification of a putative autocrine bone morphogenetic protein-signaling pathway in human ovarian surface epithelium and ovarian cancer cells

Bone morphogenetic proteins (BMPs) are members of the TGFbeta superfamily of cytokines that are involved in development, differentiation, and disease. In an analysis of normal ovarian surface epithelium (OSE) and ovarian cancer (OC) cells, we observed BMP4 mRNA expression and found that primary OC cells produce mature BMP4. In addition, each member of the downstream signaling pathway was expressed in primary OSE and OC cells. Smad1 was phosphorylated and underwent nuclear translocation in normal OSE and OC cells upon treatment with BMP4. Interestingly, the BMP target genes ID1 and ID3 were up-regulated 10- to 15-fold in primary OC cells, compared with a 2- to 3-fold increase in normal OSE. The growth of several primary OC cells was relatively unaltered by BMP4 treatment; however, long-term BMP4 treatment of primary OC cells resulted in decreased cell density as well as increased cell spreading and adherence. These data demonstrate the existence and putative function of BMP signaling in normal OSE and OC cells, and thus the continued examination of BMP4 signaling in the regulation of these two processes will be critical to further our current understanding of the role of BMP biology in OC pathogenesis.