Twist1-IRF9 Interaction Is Necessary for IFN-Stimulated Gene Anti-Zika Viral Infection

An efficient immune defense against pathogens requires sufficient basal sensing mechanisms that can deliver prompt responses. Type I IFNs are protective against acute viral infections and respond to viral and bacterial infections, but their efficacy depends on constitutive basal activity that promotes the expression of downstream genes known as IFN-stimulated genes (ISGs). Type I IFNs and ISGs are constitutively produced at low quantities and yet exert profound effects essential for numerous physiological processes beyond antiviral and antimicrobial defense, including immunomodulation, cell cycle regulation, cell survival, and cell differentiation. Although the canonical response pathway for type I IFNs has been extensively characterized, less is known regarding the transcriptional regulation of constitutive ISG expression. Zika virus (ZIKV) infection is a major risk for human pregnancy complications and fetal development and depends on an appropriate IFN-β response. However, it is poorly understood how ZIKV, despite an IFN-β response, causes miscarriages. We have uncovered a mechanism for this function specifically in the context of the early antiviral response. Our results demonstrate that IFN regulatory factor (IRF9) is critical in the early response to ZIKV infection in human trophoblast. This function is contingent on IRF9 binding to Twist1. In this signaling cascade, Twist1 was not only a required partner that promotes IRF9 binding to the IFN-stimulated response element but also an upstream regulator that controls basal levels of IRF9. The absence of Twist1 renders human trophoblast cells susceptible to ZIKV infection.

Exploring the nuances between BRCA1 and 2: A multiomic analysis

5580

Background: Emerging data suggests that key differences exist between BRCA1 and BRCA2 associated OC, including response to therapy and survival. The purpose of this study was to identify the gene expression profiles, interacting pathways and immune microenvironment of BRCA1 mutant (BRCA1mut), BRCA2 mutant (BRCA2mut) and homologous recombination wild-type (HRwt) associated high grade serous OC (HGSOC). Methods: Next-generation sequencing (592, NextSeq; WES, NovaSeq) and Whole Transcriptome Sequencing (NovaSeq) (Caris Life Sciences, Phoenix, AZ) were performed in 8196 OC tumors classified into 3 groups: BRCA1mt; BRCA2mt; and HRwt. BRCA mutations were defined as variants that result in loss-of-function of the BRCA protein and HRwt was defined as samples negative for aberrations in both BRCA1 and BRCA2, as well as for 28 other homologous recombination genes Microsatellite instability (MSI) was tested by fragment analysis, IHC and NGS. Tumor mutational burden (TMB) was measured by totaling somatic mutations (TMB-H: >10 mutations/MB). LOH cut-off >16%. Immune cell infiltrates were calculated by XCell. Differential gene expression was calculated using Limma. Significance was determined using chi-square and Wilcoxon rank sum test and adjusted for multiple comparisons (q-value < 0.05). Results: We identified 677 BRCA1mt, 439 BRCA2mt, and 7080 HRwt OC tumors. HGSOC made up the largest portion of BRCA1mt (523; 77%), BRCA2mt (306; 70%), and HRwt (4281; 60%) tumors. TP53 was most commonly mutated gene in all three groups. LOH (>16%) was highest in BRCA1mt (86.8%) compared to BRCA2mt (74.8%) and HRwt (38.4%). TMB-H was highest in BRCA2mt (6.29%) than in BRCA1mt (1.35%) and HRwt (0.91%) HGSOC (all q < 0.05). Expression of immune checkpoint genes CD80, CD86, CD274, CTLA4, HAVCR2/TIM3, IFNG, IDO1, LAG3, PDCD1 and PDCD1LG2 were significantly higher in BRCA1 and BRCA2 mt compared to HRwt HGSOC (FC: 1.12-1.59, q < 0.05). HRwt tumors had decreased infiltration of Activated Dendritic cells compared to BRCA1mt, and lower Macrophage M1 compared to both BRCA1mt and BRCA2mt (all q < 0.05). Additionally, T-inflamed score was higher in BRCA1mt compared to HRwt, while IFN score was higher in BRCA1mt compared to both BRCA2mt and HRwt (all q < 0.05). From 17,408 genes with measured expression. 522 (3.0%) differentially expressed genes (DEG) were found between BRCA2mt vs BRCA1mt; 1487 (8.54%) between BRCA2mt vs HRwt; and 9297 (53.4%) between BRCA1mt and HRwt HGSOC. Pathway analysis identified Fatty Acid Metabolism, Myc targets, ROS pathway, Oxidative Phosphorylation, and Wnt B-catenin signaling pathways as differentially regulated between the 3 groups. Conclusions: We describe the genomic, pathway and immunologic analyses in the largest cohort of BRCA1 and 2 mutated HGSOC to date. Both metabolic and immune response pathways are differentially regulated between the groups. Results can potentially inform targeted therapeutic studies based on unique BRCA genotype.

Connective tissue growth factor expression maintains the epithelial phenotype of ovarian cancer in early epithelial to mesenchymal transition

e17544

Background: Epithelial to Mesenchymal Transition (EMT) is essential to the process of metastasis in ovarian cancer (OC). Early expressions of proteins and pathways during EMT essential for understanding mechanism and potential therapeutic targets in OC. The aim of our study is to evaluate the role and mechanism of Connective Tissue Growth Factor (CTGF) in OC. Methods: R182 and R2615 are well-characterized epithelial OC cell lines. CTGF expression +/- Transforming Growth Factor -b (TGF-b) was determined via Western blot. R182 and R2615 CTGF knock out (KO) were derived utilizing a Cas9/CRISPR-Cas9 lentivirus plasmid vector and confirmed via PCR. Anoikis resistance and invasion assays were performed to characterize phenotypes of R182 and R2615 wild type (WT) and KO cells. For anoikis resistance, cells were plated in triplicate in an ultra-low adhesive (ULA) cell plate Promega CellTiter assay which measured cell viability quantified by absorbance at 450 nm at 0, 24, 48, and 72 hrs. For invasion assay, 3000 cells were suspended in 50% reduced growth factor Basement Membrane Extract. Human recombinant CTGF was added at 50 and 100 ng/mL concentrations. Cells were plated in tissue culture plate and placed in Cytation 5/Biospa and imaged at 4-hour interval for up to 6 days. Western blot evaluated expression of mesenchymal markers. Chemo-sensitivity was measured by half maximal inhibitory concentration (IC50) for Cisplatin between the WT and KO cells. RNA sequence analysis was performed for both R182 WT and KO cells and analyzed utilizing iPathway Guide. Results: CTGF is constitutively expressed in R182 and R2615 OC cells line as early as 6 hrs of culture and after 30 min of TGF-b treatment. Loss of CTGF promoted anoikis resistance. At 72 hr, R182 CTGF WT cells displayed 75% viability while R182 KO only have 10% viability. Further, we demonstrated that loss of CTGF increases invasion. Administration of exogeneous CTGF in KO cells suppresses invasion in a dose dependent manner demonstrated. Along with epithelial markers CK-18 and beta-catenin, the KO cells expressed the mesenchymal marker SNAIL. No difference in chemo-sensitivity to Cisplatin was seen between WT and KO in either cell line. RNA sequence analysis identified 1106 out of 14054 differentially expressed genes between the WT and KO cells. PI3KAkt, cell adhesion molecules and ECM receptor interaction were pathway that were most significantly regulated. Conclusions: CTGF expression maintains the epithelial phenotype of OC cells during EMT. Loss of CTGF allows anoikis resistance and invasion which are vital characteristics in the metastatic nature of OC. We suggest that loss of CTGF expression in OC cells could be a biomarker for more aggressive OC.

Using Live Imaging and FUCCI Embryonic Stem Cells to Rank DevTox Risks: Adverse Growth Effects of PFOA Compared With DEP Are 26 Times Faster, 1,000 Times More Sensitive, and 13 Times Greater in Magnitude

Fluorescent ubiquitination-based cell cycle indicator (FUCCI) embryonic stem cells (ESCs), which fluoresce green during the S-G2-M phases, generate an S-shaped curve for the accumulation of cells during normal stemness (NS) culture with leukemia-inhibitory factor (LIF). Since it was hypothesized that a culture of ESCs was heterogeneous in the cell cycle, it was expected that increased S-G2-M-phases of the cell cycle would make an S-shaped curve parallel to the accumulation curve. Unexpectedly, it was observed that the fraction of FUCCI ESCs in green decreases over time to a nadir at ∼24 h after previous feeding and then rapidly enters S-G2-M-phases after medium change. G1 delay by infrequent medium change is a mild stress, as it does not affect growth significantly when frequency is increased to 12 h. Perfluoro-octanoic acid (PFOA) and diethyl phthalate (DEP) were used as examples of members of the per- and polyfluoroalkyl substances (PFAS) and phthalate families of chemicals, respectively. Two adverse outcomes were used to compare dose- and time-dependent effects of PFOA and DEP. The first was cell accumulation assay by time-lapse confluence measurements, largely at Tfinal/T74 h. The second was by quantifying dominant toxicant stress shown by the suppression of mild stress that creates a green fed/unfed peak. In terms of speed, PFOA is 26 times faster than DEP for producing a time-dependent LOAEL dose at 100 uM (that is, 2 h for PFOA and 52 h for DEP). PFOA has 1000-fold more sensitive LOAEL doses than DEP for suppressing ESC accumulation (confluence) at day 3 and day 2. There were two means to compare the magnitude of the growth suppression of PFOA and DEP. For the suppression of the accumulation of cells measured by confluence at Tfinal/T74h, there was a 13-fold suppression at the highest dose of PFOA > the highest dose of DEP. For the suppression of entry into the cell cycle after the G1 phase by stress on day 1 and 2, there is 10-fold more suppression by PFOA than DEP. The data presented here suggest that FUCCI ESCs can assay the suppression of accumulated growth or predict the suppression of future growth by the suppression of fed/unfed green fluorescence peaks and that PFOA's adverse effects are faster and larger and can occur at more sensitive lower doses than DEP.

Identification of key signaling pathways induced by SARS-CoV2 that underlie thrombosis and vascular injury in COVID-19 patients

The SARS-CoV-2 pandemic has led to hundreds of thousands of deaths and billions of dollars in economic damage. The immune response elicited from this virus is poorly understood. An alarming number of cases have arisen where COVID-19 patients develop complications on top of the symptoms already associated with SARS, such as thrombosis, injuries of vascular system, kidney, and liver, as well as Kawasaki disease. In this review, a bioinformatics approach was used to elucidate the immune response triggered by SARS-CoV-2 infection in primary human lung epithelial and transformed human lung alveolar. Additionally, examined the potential mechanism behind several complications that have been associated with COVID-19 and determined that a specific cytokine storm is leading to excessive neutrophil recruitment. These neutrophils are directly leading to thrombosis, organ damage, and complement activation via neutrophil extracellular trap release.

Comment on "Osteopontin, Macrophage Migration Inhibitory Factor and Anti-Interleukin-8 Autoantibodies Complement CA125 for Detection of Early Stage Ovarian Cancer" Cancers 2019, 11, 596: Markers for Early Detection of Ovarian Cancer

We read with interest the recent publication by Guo et al [...].

Abstract A62: TRX-1 targets chemoresistant tumor-initiating cells and prolongs survival in a recurrent ovarian cancer animal model

Background: Ovarian cancer is the leading cause of mortality from gynecologic cancers due to the high incidence of chemoresistance and disease recurrence. Disease recurrence is thought to occur due to the presence of residual disease following first-line standard of care (i.e. optimal debulking and chemotherapy). Residual disease post chemotherapy is composed of a unique population of chemoresistant cancer cells with stemness properties and a high capacity for tumor repair. Currently, there are no available options that can target these cells. The objective of this study was to develop a new therapeutic modality that will target chemoresistant ovarian cancer stem cells (OCSC) and consequently prevent recurrence and improve survival. To achieve this objective we developed a library of super-benzopyran (SBP) analogues and identified TRX-1 as the most potent analogue able to induce OCSC cell death in a short period of time. Moreover, in contrast to Cisplatin and Paclitaxel, TRX-1 is able to induce a persistent growth inhibitory effect both in vitro and in vivo thus improving overall survival in a mouse model of recurrent ovarian cancer.

Materials and methods: A panel of SBP analogues were generated and activity was determined by testing against pure clones of CD44+/MyD88+ OCSC. In vitro efficacy was assessed using the IncucyteTM kinetic imaging platform complemented by CelltoxTM dye labeling. In vivo efficacy was tested using an intra-peritoneal (i.p.) a mouse model of recurrent ovarian cancer1.

Results: TRX-1 was the most potent analogue identified and is able to induce cell death in all OCSC clones tested (IC50 of 136 nM). We observed that 2h in vitro exposure to 2μM TRX-1 was sufficient to induce a sustained growth inhibitory effect in OCSC, hence the cells were not able to recover growth potential even after removal of the drug. In contrast, OCSC exposed for up to 24h with the same dose of Cisplatin or Paclitaxel were able to recover. In vivo, animals bearing residual tumors after Paclitaxel treatment demonstrated tumor progression when further maintained with vehicle or Paclitaxel indicating Paclitaxel resistance. In contrast, maintenance with TRX-1 was able to effectively decrease tumor burden (p = 0.02) and prevent recurrence. In addition, combination treatment with TRX-1 and Cisplatin was able to significantly improve survival (p&lt;0.001) compared to Cisplatin alone.

Conclusion: We describe the in vitro and in vivo anti-tumoral effect of a novel compound, TRX-1, which exhibits significant efficacy against chemoresistant OCSC and is able to prevent recurrence in a chemoresistant in vivo model. Recurrence characterized by chemoresistance is the main cause of mortality in ovarian cancer patients. Previous studies from our laboratory have shown that conventional chemotherapy is not effective against OCSC and cannot prevent recurrence. Our finding that TRX-1, by targeting OCSC can prevent recurrence in vivo as maintenance therapy or in combination with chemotherapy provides a new opportunity for developing new therapeutic strategies that can improve survival in ovarian cancer patients.

Citation Format: Ayesha Alvero, Eydis Lima, Mary Pitruzzello, Yang Yang-Hartwich, David Brown, Andrew Heaton, Gil Mor. TRX-1 targets chemoresistant tumor-initiating cells and prolongs survival in a recurrent ovarian cancer animal model. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A62.

Murine model for non-invasive imaging to detect and monitor ovarian cancer recurrence

Epithelial ovarian cancer is the most lethal gynecologic malignancy in the United States. Although patients initially respond to the current standard of care consisting of surgical debulking and combination chemotherapy consisting of platinum and taxane compounds, almost 90% of patients recur within a few years. In these patients the development of chemoresistant disease limits the efficacy of currently available chemotherapy agents and therefore contributes to the high mortality. To discover novel therapy options that can target recurrent disease, appropriate animal models that closely mimic the clinical profile of patients with recurrent ovarian cancer are required. The challenge in monitoring intra-peritoneal (i.p.) disease limits the use of i.p. models and thus most xenografts are established subcutaneously. We have developed a sensitive optical imaging platform that allows the detection and anatomical location of i.p. tumor mass. The platform includes the use of optical reporters that extend from the visible light range to near infrared, which in combination with 2-dimensional X-ray co-registration can provide anatomical location of molecular signals. Detection is significantly improved by the use of a rotation system that drives the animal to multiple angular positions for 360 degree imaging, allowing the identification of tumors that are not visible in single orientation. This platform provides a unique model to non-invasively monitor tumor growth and evaluate the efficacy of new therapies for the prevention or treatment of recurrent ovarian cancer.

Abstract 1974: Ovulatory wound: the site of origin for ovarian serous carcinoma

Background: New clinical and molecular studies suggest that HGSOC originates from the neighboring fallopian tubes, rather than the surface epithelial layer of the ovary. However, very little is known about the process of tubal malignant cells migrating and implanting into ovary. Our research focuses on understanding how the extraovarian malignant cells implant into the ovary and how ovulation affects the process of their migration and implantation.

Method: Tumor initiating cells (TICs) isolated from human HGSOC were labeled by red fluorescent protein (RFP)-expressing lentivirus and subcutaneously or intrauterine injected to immunocompromised mice. Hormones (PMS and HCG) were interperitoneally injected to induce superovulation in mice. In the in vitro models, TICs were cultured with the granulosa cell conditional medium and the extra cellular matrix (ECM) extracted from ovarian stroma cells to evaluate their effects on the migration and attachment of TICs

Result: Superovulation increased the ovarian tumor-forming rate from 38% (15/39 in control group) to 100% (24/24 in supervolation group). The increased frequency of ovulation enhances the formation of ovarian tumors in mouse models. In the intrauterine injection model, we were able to trace the migration of TICs towards ovaries and capture the early implantation of TICs inside ovaries in 5-10 days after the injection. We detected stage I ovarian tumors in mice. The tumors are encapsulated in the ovary and covered by the intact surface epithelial layer. These tumor cells closely interacted with the stroma of ovary, particularly the structure of corpus luteum. The granulosa cells secreted stromal cell-derived factor 1 (SDF-1, also known as CXCL12). SDF-1 attracts TICs that express CXCR4 (the receptor of SDF-1) to ovulatory wounds. Upon ovulation the ovulatory wounds expose the stroma of ovary, which provides a collagen enriched ECM for TICs to attach.

Conclusion: The unique ovulatory wound microenvironment attracts the malignant cells to migrate towards the ovary and creates access for the malignant cells to implant in the collagen-enriched ECM in the stroma of ovary. The new mechanisms revealed by our data may explain why increased ovulation is associated with epithelial ovarian cancer. Our findings support the “extra-ovarian origin” theory and will help us better understand the initiation and progression of HGSOC.

Citation Format: Yang Yang-Hartwich, Marta Gurrea, Natalia Sumi, Jennie Holmberg, Vinicius Craveiro, Ayesha Alvero, Gil Mor. Ovulatory wound: the site of origin for ovarian serous carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1974. doi:10.1158/1538-7445.AM2014-1974

The duplicitous origin of ovarian cancer

The past few decades have seen many advances in the treatment of a variety of cancers. Unfortunately, for ovarian cancer, which is the most lethal type of gynecologic malignancy, no new therapeutic approach has been successfully introduced since the 1990s. Ovarian cancer is usually detected in later stages, when remission rates are high and tumors are resistant to chemotherapy. Little is known about the primary lesion in ovarian cancer. Recently, it has been shown that the origin of ovarian cancer can be cells from adjacent tissue or cells from other primary tumors, which make their way to the ovaries due to the unique nature of their microenvironment during ovulation. The tumor in ovarian cancer is heterogeneous and hierarchically organized. In this review, we discuss the role of ovarian cancer stem cells in the process of tumor formation and recurrence. We propose the need to shift the paradigm away from the classification of ovarian cancer as a single disease with a single cellular origin. Understanding the complexity of the disease will facilitate devising new methods for fighting this cancer and improving the life of many women inflicted with the disease.

High frequency of putative ovarian cancer stem cells with CD44/CK19 coexpression is associated with decreased progression-free intervals in patients with recurrent epithelial ovarian cancer

OBJECTIVE

Epithelial ovarian cancer (EOC) cells with CD44 and CK19 coexpression may represent a subset of ovarian cancer stem cells (OCSCs). This study was conducted to evaluate the correlation of the frequency of putative OCSCs (CD44 + CK19 + OCSCs) with the clinicopathologic features and the prognostic value in patients with recurrent advanced stage EOC.

METHODS

A retrospective study was carried out on 33 patients with EOC and a uniformly treated tissue microarray was constructed. A multiplexed, immunofluorescence-based method of automated in situ quantitative measurement of protein analysis was used for evaluation of the frequency or density of CD44 + CK19 + OCSCs in EOC.

RESULTS

The mean follow-up time was 42.8 ± 27.1 months. High frequency of EOC cells with CD44+ or CD44+/CK19+ was associated with chemoresistance (P = .033 and P = .02, respectively). Using K-M analysis with log-rank test, a high frequency of putative OCSCs was associated with short disease-free interval (7.9 months vs 20.9 months, P = .019). In univariable analysis, the frequency of OCSCs, International Federation of Gynecology and Obstetrics stage and residual tumor volume were significant predictor variables and were entered into multivariable analysis (P = .019, .037, and .005, respectively). Although no independent significant predictor was found, the frequency of putative OCSCs was the most promising predictor variable compared with the other 2 variables (hazard ratio = 2.344, P = .052).

CONCLUSION

Our findings suggest that high frequency of OCSCs (CD44+ and CK19+) in epithelial ovarian tumors correlates with short progression-free intervals.

Multimodality animal rotation imaging system (Mars) for in vivo detection of intraperitoneal tumors

PROBLEM Ovarian cancer stem cells (OCSCs) have been postulated as the potential source of recurrence and chemoresistance. Therefore identification of OvCSC and their complete removal is a pivotal stage for the treatment of ovarian cancer. The objective of the following study was to develop a new in vivo imaging model that allows for the detection and monitoring of OCSCs. METHOD OF STUDY  OCSCs were labeled with X-Sight 761 Nanospheres and injected intra-peritoneally (i.p.) and sub-cutaneously (s.c.) to Athymic nude mice. The Carestream In-Vivo Imaging System FX was used to obtain X-ray and, concurrently, near-infrared fluorescence images. Tumor images in the mouse were observed from different angles by automatic rotation of the mouse. RESULTS  X-Sight 761 Nanospheres labeled almost 100% of the cells. No difference on growth rate was observed between labeled and unlabeled cells. Tumors were observed and monitoring revealed strong signaling up to 21 days. CONCLUSION  We describe the use of near-infrared nanoparticle probes for in vivo imaging of metastatic ovarian cancer models. Visualization of multiple sites around the animals was enhanced with the use of the Carestream Multimodal Animal Rotation System.

Ovarian cancer stem cells and inflammation

Epithelial ovarian cancer (EOC) is the fourth leading cause of cancer-related deaths in women in the United States and the leading cause of gynecologic cancer deaths. The major limiting factor in the treatment of ovarian cancer is recurrence and chemoresistance. Individuals who succumb to advanced-stage ovarian cancer inevitably become refractory to chemotherapy, resulting in disease progression and death. The source of recurrence and lack of response to chemotherapy is unknown. The focus of this review is to evaluate the question of recurrence and chemoresistance based on the concept of the cancer stem cells and inflammation.

Abstract 3405: Epithelial ovarian cancer stem cells are the source of metastatic progenitor cells

Background: Metastatic disease significantly contributes to mortality in ovarian cancer. Unfortunately, the source of metastatic cells and the processes involved in the generation of metastatic ovarian cancer is not well characterized. Epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial (MET) transitions have key roles in the process of tumor formation and metastasis. In this study we tested the hypothesis that epithelial ovarian cancer stem cells (EOC stem cells) are the source of metastasis. We demonstrate that the EOC stem cells can undergo both EMT and MET to yield cells with metastatic potential in vitro and create metastatic ovarian cancer in vivo.

Methods: EOC stem cells were cultured in very confluent conditions for 30d. Changes in cellular morphology were monitored using the IncuCyte video imaging system. Levels of epithelial, mesenchymal, and stem cell markers were determined using RT-qPCR, Western blot analyses, and Flow cytometry. Gene expression profile was determined using EMT gene array.

Results: I.p. injection of a pure culture of EOC stem cells suspended in matrigel in nude mice generated a solid tumor mass, whereas, injection of EOC stem cells without matrigel created carcinomatosis. Molecular characterization showed that the cells forming the solid tumor maintain an epithelial phenotype whereas cells forming the carcinomatosis acquire the mesenchymal markers Vimentin and Twist-1. In vitro, EOC stem cells grown in very confluent cultures formed viable mesenchymal-like spheroid cells (mspheroid cells) by day 30. EMT array results showed that the newly formed spheroids lost epithelial markers Ck18 and Ck19 but gained mesenchymal markers, Foxc2, Slug, Twist-1 and Vimentin. Moreover, the mspheroid cells exhibited a 4-fold increase in invasion capacity and significantly higher levels of MMP2 and MMP9 compared to the EOC stem cells. Finally, mspheroid cells plated in tissue culture flask re-attached and formed a monolayer of epithelial cells loosing expression of Foxc2 and Slug, suggesting MET. These results were not observed on parallel experiments performed on mature epithelial ovarian cancer cells (mOCCs), which do not possess stemness properties.

Conclusion: We showed that the in vitro generation of mspheroid cells with highly metastatic potential and the creation of carcinomatosis in vivo occur only from a pure culture of EOC stem cells and not from cultures of mOCCs. Furthermore, we demonstrate the involvement of EMT and MET in this process. These results suggest that the EOC stem cells represent an early progenitor stage in the primary tumor, which have the capacity to differentiate, acquire the ability to detach and metastasize, and revert back to an epithelial phenotype at distant sites, thereby establishing metastatic disease.

Acknowledgements: This study is supported in part by the Sands foundation, Brozman foundation, and grant from the NCI (RO1CA127913)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3405. doi:10.1158/1538-7445.AM2011-3405

Abstract 4229: Wound repair promotes ovarian cancer stem cell self-renewal

Background: In normal tissues following injury, there is an expansion of tissue specific stem cells prior to their differentiation to initiate injury repair. Once the tissue is repaired, the stem cells return to a quiescent state. Tumor tissue, might follow similar characteristics as in normal tissues, but the control of the expansion process may be significantly altered. Recently, ovarian cancer stem cells (ovCSC) were isolated from ovarian cancer tissue and ascites using CD44/CK18 as markers. We hypothesize that these cells play a critical role in tumor repair and renewal. To test this hypothesis, we used an in vitro wound/healing system.

Methods: Cells were plated in an Essen ImageLock plate and wounds were made using an Essen WoundMaker. This sytem allows the generation of consistent wound locations and widths and precise imaging of the wound area. The healing process is monitored using an insitu imaging system (IncuCyte, Essen Instruments, NH) that records and quantifies the repair process in real time. Levels of cancer stem cell markers, CD44, Oct-4, and β-catenin were determined by Western blot analysis or Real Time PCR. Levels of cytokines and chemokines were determined using Luminex Technology.

Results: Initially we tested whether an in vitro wound/healing system can be used as a renewal model. Interestingly, ovCSCs showed a well coordinated and organized response to the wound. First, the cells created a “straight line” to replace the irregular edge of the wound. Afterwards, the cells proliferated towards the wound, repairing the wound until confluence was reached. Analysis of cancer stem cell markers by Western blot revealed that the cells which repaired the wound maintained CD44, CK18, Oct4, and β-catenin, previously shown as ovCSC markers. Additionally, the process of repair was characterized by significant and differential up-regulation in IL-6, GRO-α, and MCP-1 expression and secretion. Interestingly, the CD44 expression was increased in wounded wells when compared to control. Moreover, using specific primers for CD44 variant isoforms we found that wound healing promotes expression of different CD44 forms.

Conclusions: In this study we demonstrate ovCSCs have the capacity to repair an in vitro wound and that this process is accompanied by increased CD44 expression and cytokine secretion. This increased capacity of self renewal can lead to the accumulation of a large pool of progenitor cells, which has the potential to individually spread to other areas of the body as metastatic cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4229.

Abstract B75: TWISTing Stemness, Inflammation, and Proliferation of Epithelial Ovarian Cancer Cells through MIR199A2/214

Introduction: Twist1, a basic helix-loop-helix (bHLH) transcription factor, has an important role in tumor biology by regulating epithelial-mesenchymal transition. It also functions as a transcription repressor in NFκB-dependent cytokine expression. Recently, we reported the identification and characterization of epithelial ovarian cancer (EOC) cells with stem-like properties (Type I EOC cells). At the microRNA level, Type I EOC cells are characterized by low levels of hsa-miR-199a2 and hsa-miR-214. We also demonstrated the capacity of Type I EOC cells to differentiate into mature ovarian cancer cells (Type II EOC cells), which has lost stemness potential and express high levels of both hsa-miR-199a2 and hsa-miR-214. We also showed previously that hsa-miR-199a2 is able to regulate the levels of IKKβ and therefore have a direct effect on the NFκB pathway. Still, another group reported the regulatory control of hsa-miR-214 on the Akt pathway. In this study, we show that Twist1 is able to regulate the miR-199a2/214 cluster in EOC cells and can therefore control both NFκB and Akt pathways.

Methods: 5′-RACE and 3′-RACE was used to clone the full length pre-miR-199a gene. Real-time PCR was used to determine the levels of Twist1 and miR-199a2/214. Twist1 was knocked-down in Type II EOC cells using siRNA. The effect of Twist1 knockdown on levels of IKKβ was determined by Western blot analysis. Cytokines were quantified using Luminex technology.

Results: Characterization of full length of pre-miR-199a2 transcript reveals that the MIR199A2 gene contains a human microRNA cluster, miR-199a2/214, and pre-miR-199a2 within the human Dnm3os gene (NCBI GeneID 474332). PCR analysis showed low levels of Twist1 and miR-199a2/214 in Type I EOC cells but high levels of expression in Type II EOC cells. Knockdown of Twist1 in Type II cells induce a significant decrease in the levels both hsa-miR-199a2 and hsa-miR-214, and significant increase in IKKβ expression. Ectopic expression of hsa-miR-199a2 partially reverse the effect of Twist-1 knockdown on the levels of IKKβ. The combination of knockdown Twist1 and TNFα stimulation in Type II EOC cells significantly increase Rantes, an NFκB-dependent cytokine.

Conclusion: We demonstrate for the first time that Twist1 plays a feedback role for the NFkB pathway by repressing IKKβ expression through hsa-miR-199a2. Twist1 inhibition of IKKβ expression through regulating hsa-miR-199a2, represents a novel negative feedback loop for the NFκB pathway. The demonstration that Twist1 can regulate the miR-199a2/214 cluster and therefore both the IKKβ and Akt survival pathways, suggests the potential role of Twist1 in EOC differentiation. Furthermore it opens the opportunity to develop new approaches for targeting the ovarian cancer stem cells.

Citation Information: Cancer Res 2009;69(23 Suppl):B75.

Abstract 2029: Identification and characterization of cancer stem cells in ovarian cancer

Introduction: One of the major burdens in the treatment of epithelial ovarian cancer (EOC) is the high percentage of recurrence characterized by chemoresistance. The biology underlying the tumor’s high capacity for recurrence has not been elucidated. Tumors are made of a heterogeneous cell population consisting of both cancer and non-cancer cells. New data suggest that even the cancer cell population is heterogeneous and contains a small subset of cells, the cancer stem cells (CSC), which constitute a reservoir that can self-renew and therefore maintain the tumor. CSC can divide and expand their pool and also differentiate into non-CSC, which constitute the bulk of the tumor. Contrary to CSC, the non-CSC are rapidly dividing and therefore sensitive to therapies, which target highly proliferative cells. In the present study we identified and characterized the CSC of EOC.

Methods: EOC cells were isolated from malignant ovarian cancer ascities and solid tumors (n=80). Marker expression was determined using Flow Cytometry, Western Blots and Immunocytochemistry. Xenograft nude mice model was used for tumor growth by injecting cancer cells either s.c. or i.p. Isolation of CD44+ population was done using FACS. Cancer cells were maintained in culture as previously described {Kamsteeg, 2003 #358}

Results: CSC were identified in EOC cells isolated form ascites and solid tumors with the following characteristics: 1) cellular markers: CD44+, MyD88+, constitutive NFκB activity and cytokine and chemokine production, high capacity for repair, chemoresistance to conventional chemotherapies, resistance to TNFα-mediated apoptosis, capacity to form spheroids in suspension, and unique microRNA phenotype; 2) tumor formation in animals: 100% CD44+ cells formed tumors which contained 10% CD44+ and 90% CD44-negative cells. Re-injection of isolated CD44+ cells from previous engraftment was able to again recapitulate the original tumor phenotype. Isolation and in vitro treatment of CD44+ cells from fresh samples showed resistance to carboplatin and paclitaxel. In contrast, the sorted CD44-negative cell population from the same sample/patient was chemosensitive.

Conclusion: Present chemotherapy modalities eliminate the bulk of the tumor but it leaves a core of cancer cells with high capacity for repair and renewal. CSC corresponds to the core of malignant cells that promotes recurrence and chemoresistance. Identification of these cells represents the first step in the development of therapeutic modalities that can eliminate not only the bulk of the tumor but its source. Prevention of recurrence will be achieved only with therapies targeting this cell population.

Trophoblast?Macrophage Interactions: a Regulatory Network for the Protection of Pregnancy

PROBLEM

Macrophages are one of the first immune cells observed at the implantation site. Their presence has been explained as the result of an immune response toward paternal antigens. The mechanisms regulating monocyte migration and differentiation at the implantation site are largely unknown. In the present study, we demonstrate that trophoblast cells regulate monocyte migration and differentiation. We propose that trophoblast cells 'educate' monocytes/macrophages to create an adequate environment that promote trophoblast survival.

METHOD OF STUDY

CD14(+) monocytes were isolated from peripheral blood using magnetic beads. Co-culture experiments were conducted using a two-chamber system. Monocytes were stimulated with lipopolysaccharide (LPS) and cytokine levels were determined using multiplex cytokine detecting assay.

RESULTS

Trophoblast cells increase monocyte migration and induce a significant increase in the secretion and production of the pro-inflammatory cytokines [interleukin-6 (IL-6), IL-8, tumor necrosis factor-alpha] and chemokines (growth-related oncogen-alpha, monocyte chemoattractant protein-1, macrophage inflammatory protein-1beta, RANTES). Furthermore, the response of monocytes to LPS was different in monocytes pre-exposed to trophoblast cells.

CONCLUSION

The results of this study suggest that trophoblast cells are able to recruit and successfully educate monocytes to produce and secrete a pro-inflammatory cytokine and chemokine profile supporting its growth and survival. Furthermore we demonstrate that trophoblast cells can modulate monocytes response to bacterial stimuli.

Novel method for predicting chemoresistance to paclitaxel in epithelial ovarian cancer patients

15007

Background: No available test exists to guide the selection of effective chemotherapeutic regimen in recurrent ovarian cancer. Preliminary studies in our lab have identified a protein, MyD88, a major component in the inflammatory pathway, to be highly expressed in epithelial ovarian cancer cells that exhibit primary or acquired Paclitaxel chemoresistance. The objective of this study was to develop a sensitive approach that can detect expression of MyD88 in ovarian cancer tissue. We report the development of a test based on Laser capture microdissection that allows detection of MyD88 in a 6000 cell sample. Methods: Tumor tissue was obtained at surgery from epithelial ovarian cancer patients and snap-frozen in liquid nitrogen. Eight micron sections were prepared on polyethylene covered glass slides and tumor cells were dissected with a Laser capture microdissection system. Protein expression was detected by Western blot analysis. Results: Protein expression was detected by Western blot analysis in 1000 microdissected cells. An inverse correlation was observed between MyD88 expression in tumor cells and clinical response to Paclitaxel. Furthermore, this method allows the isolation of CD-45 positive cells from the tumor and analysis of their protein expression. Conclusions: We describe for the first time a method that will allow us to predict chemoresistance. Laser capture microdissection is a powerful technique that can be used to study the protein profile of each of the cellular components present in the tumor microenvironment. This technique will facilitate our understanding of the proteins necessary for tumor growth and may help to identify novel markers or potential protein targets.

No significant financial relationships to disclose.

XIAP is highly expressed in melanoma and is associated with chemotherapy resistance

8008

Background: Chemoresistance is a major problem in treating melanoma. The X-linked inhibitor of apoptosis (XIAP) is associated with chemoresistance in other cancers. Here we characterize XIAP expression in primary and metastatic melanomas and determine whether XIAP plays a role in chemoresistance. We report differential expression of XIAP between primary and metastatic melanomas and benign nevi. We demonstrate that inhibition of XIAP expression by Phenoxodiol can reverse chemoresistance. Methods: We employed tissue microarrays containing specimens from 548 melanoma patients and 540 benign nevi. XIAP expression was evaluated by an automated method for in situ quantitative analysis of protein levels (AQUA). We use S100 to define pixels as melanoma (tumor mask) within the array spot, and measure intensity of XIAP expression using Cy5 conjugated antibodies within the mask. AQUA scores were correlated with clinical and pathological variables. Cell viability after exposure to Carboplatin and Phenoxodiol was determined in 3 melanoma cell strains using the CellTiter 96 Assay. Apoptosis was measured using the Caspase-3/7 GloTM Assay, and levels of XIAP and Caspase 2 were assessed by Western blots. Results: XIAP expression was significantly higher in melanomas than in nevi (P<0.0001), and higher in metastatic than in primary specimens (P<0.0001). All three melanoma cell strains examined were highly resistant to Carboplatin, and moderately resistant to Phenoxodiol. Pre-treatment with Phenoxodiol prior to Carboplatin induced a significant decrease in XIAP expression, which correlated with remarkable sensitization to Carboplatin. Conclusions: XIAP expression is higher in malignant melanocytes than in their benign counterparts. Expression is higher in early stage disease specimens than in metastatic specimens, suggesting an association with disease aggression. Phenoxodiol is a well tolerated drug, and has been shown to inhibit XIAP expression in ovarian cancer. Here we demonstrate that melanoma is resistant to Carboplatin, possibly due to XIAP expression. In vitro inhibition of XIAP by Phenoxodiol sensitizes melanoma cells to Carboplatin. This drug combination warrants further investigation as a therapeutic approach for metastatic melanoma.

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A novel immortalized human endometrial stromal cell line with normal progestational response

Obtaining primary human endometrial stromal cells (HESCs) for in vitro studies is limited by the scarcity of adequate human material and the inability to passage these cells in culture for long periods. Immortalization of these cells would greatly facilitate studies; however, the process of immortalization often results in abnormal karyotypes and aberrant functional characteristics. To meet this need, we have introduced telomerase into cultured HESCs to prevent the normal shortening of telomeres observed in adult somatic cells during mitosis. We have now developed and analyzed a newly immortalized HESC line that contains no clonal chromosomal structural or numerical abnormalities. In addition, when compared with the primary unpassaged parent cells, the new cell line displayed similar biochemical endpoints after treatment with ovarian steroids. Classical decidualization response to estradiol plus medroxyprogesterone acetate were seen in both morphologically, and progestin was seen to induce or regulate the expression of IGF binding protein-1, fibronectin, prolactin, tissue factor, plasminogen activator inhibitor-1, and Fas/Fas ligand. In summary, an immortalized HESC line has been developed that is karyotypically, morphologically, and phenotypically similar to the primary parent cells, and it is a powerful and consistent resource for in vitro work.