ID8 Cells Research Articles

Artesunate promotes Th1 differentiation from CD4+ T cells to enhance cell apoptosis in ovarian cancer via miR-142.

The aim of this study was to evaluate the influence of artesunate on Th1 differentiation and its anti-tumor effect on ovarian cancer. A Murine ovarian cancer model was established by ID8 cells transplantation. The expression of miR-142 and Sirt1 proteins in peripheral CD4+ T cells were quantified with qRT-PCR and western blot, respectively. Peripheral CD4+ T cells were induced for Th1 differentiation. The percentages of apoptosis of Th1/CD4+ T cells and ovarian cancer cells were analyzed by flow cytometry. The IFN-γ level was examined through enzyme-linked immunosorbent assay. Artesunate promoted miR-142 expression in peripheral CD4+ T cells and Th1 differentiation from CD4+ T cells. Artesunate promoted cell apoptosis of ovarian cancer cells by inducing Th1 differentiation. By up-regulating miR-142, artesunate suppressed Sirt1 level and promoted Th1 differentiation. Artesunate enhanced the pro-apoptotic effects of Th1 cells on ovarian cancer via the miR-142/Sirt1 pathway. Artesunate promoted Th1 differentiation from CD4+ T cells by down-regulating Sirt1 through miR-142, thereby enhancing cell apoptosis in ovarian cancer.

The oncogene KRAS promotes cancer cell dissemination by stabilizing spheroid formation via the MEK pathway

BackgroundPeritoneal dissemination is a critical prognostic factor in ovarian cancer. Although stabilized spheroid formation promotes cancer cell peritoneal dissemination in ovarian cancer, the associated oncogenes are unknown. In this study, we assessed the role of the KRAS oncogene in ovarian cancer cell dissemination, focusing on the stability of cells in spheroid condition, as well as the modulation of intracellular signaling following spheroid transformation.MethodsWe used ID8, a murine ovarian cancer cell line, and ID8-KRAS, an oncogenic KRAS (G12 V)-transduced ID8 cell line in this study. Spheroid-forming (3D) culture and cell proliferation assays were performed to evaluate the growth characteristics of these cells. cDNA microarray analysis was performed to identify genes involved in KRAS-associated signal transduction in floating condition. A MEK inhibitor was used to evaluate the effect on cancer peritoneal dissemination.ResultsCell viability and proliferation in monolayer (2D) cultures did not differ between ID8 and ID8-KRAS cells. However, the proportions of viable and proliferating ID8-KRAS cells in 3D culture were approximately 2-fold and 5-fold higher than that of ID8, respectively. Spheroid-formation was increased in ID8-KRAS cells. Analysis of peritoneal floating cells obtained from mice intra-peritoneally injected with cancer cells revealed that the proportion of proliferating cancer cells was approximately 2-fold higher with ID8-KRAS than with ID8 cells. Comprehensive cDNA microarray analysis revealed that pathways related to cell proliferation, and cell cycle checkpoint and regulation were upregulated specifically in ID8-KRAS cells in 3D culture, and that some genes partially regulated by the MEK-ERK pathway were upregulated only in ID8-KRAS cells in 3D culture. Furthermore, a MEK inhibitor, trametinib, suppressed spheroid formation in 3D culture of ID8-KRAS cells, although trametinib did not affect 2D-culture cell proliferation. Finally, we demonstrated that trametinib dramatically improved the prognosis for mice with ID8-KRAS tumors in an in vivo mouse model.ConclusionsOur data indicated that KRAS promoted ovarian cancer dissemination by stabilizing spheroid formation and that the MEK pathway is important for stabilized spheroid formation. Disruption of spheroid formation by a MEK inhibitor could be a therapeutic target for cancer peritoneal dissemination.

A High-Throughput Immune-Oncology Screen Identifies EGFR Inhibitors as Potent Enhancers of Antigen-Specific Cytotoxic T-lymphocyte Tumor Cell Killing.

We developed a screening assay in which luciferized ID8 expressing OVA was cocultured with transgenic CD8+ T cells specifically recognizing the model antigen in an H-2b-restricted manner. The assay was screened with a small-molecule library to identify compounds that inhibit or enhance T cell-mediated killing of tumor cells. Erlotinib, an EGFR inhibitor, was the top compound that enhanced T-cell killing of tumor cells. Subsequent experiments with erlotinib and additional EGFR inhibitors validated the screen results. EGFR inhibitors increased both basal and IFNγ-induced MHC class-I presentation, which enhanced recognition and lysis of tumor cell targets by CD8+ cytotoxic T lymphocytes. The ID8 cell line was also transduced to constitutively express Cas9, and a pooled CRISPR screen, utilizing the same target tumor cell/T-cell assay, identified single-guide (sg)RNAs targeting EGFR that sensitized tumor cells to T cell-mediated killing. Combination of PD-1 blockade with EGFR inhibition showed significant synergistic efficacy in a syngeneic model, further validating EGFR inhibitors as immunomodulatory agents that enhance checkpoint blockade. This assay can be screened in high-throughput with small-molecule libraries and genome-wide CRISPR/Cas9 libraries to identify both compounds and target genes, respectively, that enhance or inhibit T-cell recognition and killing of tumor cells. Retrospective analyses of squamous-cell head and neck cancer (SCCHN) patients treated with the combination of afatinib and pembrolizumab demonstrated a rate of clinical activity exceeding that of each single agent. Prospective clinical trials evaluating the combination of an EGFR inhibitor and PD-1 blockade should be conducted.

Sperm Protein 17 Expression by Murine Epithelial Ovarian Cancer Cells and Its Impact on Tumor Progression.

The cancer testis antigen sperm protein 17 (Sp17) is a promising antigenic target in epithelial ovarian cancer (EOC) vaccine development. However, its role in ovarian cancer is unclear. We isolated and expanded Sp17+ and Sp17− clones from the murine EOC cell line ID8, and compared their in-vitro cell growth characteristics and in-vivo tumorigenicity. We also examined the potential co-expression of molecules that may influence cancer cell survival and interaction with immune cells. These include stimulatory and immunosuppressive molecules, such as major histocompatibility class I molecules (MHC I), MHC II, cytotoxic T lymphocyte associated antigen-4 (CTLA-4), CD73, CD39, tumor necrosis factor receptor II (TNFRII), signal transducer and activator of transcription 3 (STAT3) and programmed death-ligand 1 (PD-L1). Whilst the presence of Sp17 was not correlated with the ID8 cell proliferation/growth capacity in vitro, it was critical to enable progressive tumor formation in vivo. Flow cytometry revealed that Sp17+ ID8 cells displayed higher expression of both STAT3 and PD-L1, whilst MHC II expression was lower. Moreover, Sp17high (PD-L1+MHCII−) cell populations showed significantly enhanced resistance to Paclitaxel-induced cell death in vitro compared to Sp17low (PD-L1−MHCII+) cells, which was associated in turn with increased STAT3 expression. Together, the data support Sp17 as a factor associated with in-vivo tumor progression and chemo-resistance, validating it as a suitable target for vaccine development.

Abstract A37: Epigenetic modification of ovarian cancer immunogenicity

Abstract Background: Ovarian high-grade serous carcinoma (HGSC) remains a poor prognosis disease due to its late presentation and lack of “actionable” mutations to target pharmacologically. The host immune system, however, plays a pivotal role with the presence of cytotoxic T lymphocytes and chemokines that regulate T-cell trafficking both having positive effect on survival in preclinical and clinical studies. HGSC cells can achieve immune escape via epigenetic silencing of key immune-related genes, including via DNA methylation; when DNA methylation is pharmacologically reversed, genes involved in antigen presentation, receptor-dependent immune cell stimulation, and chemokine release are reactivated. One of these genes encodes the angiostatic chemokine Cxcl10, which is a T-lymphocyte attractant. In order to elucidate other potential epigenetic mechanisms directly or indirectly involved in Cxcl10 gene silencing, we will screen a library of novel epigenetic probes that target bromodomains, methyltransferases, demethylases, and others epigenetic pathways (Structural Genomic Consortium library). Aims: We will use Trp53-/- ID8 ovarian cancer cells to perform a medium-throughput screening of 40 novel epigenetic probes, measuring cxcl10 production, with the demethylating drug decitabine as positive control. Methods: Trp53-/- ID8 cells were treated with decitabine for up to 72 hours. Cell-cycle analysis was assessed via BrdU incorporation assay. Cytokine/chemokine transcription was assessed using RT2 profiler 84 gene chemo/cytokine PCR array (Qiagen), and verified using qRT-PCR. Acid-hydrolysed DNA was subjected to mass spectrometry/liquid chromatography to quantify the mean ratio of methyl-cytosine/cytosine. Western immunoblotting was performed to test DNMT1 protein levels in protein lysates after decitabine treatment. Cxcl10 levels in supernatant were quantified by ELISA. Results: Treatment of Trp53-/- ID8 cells with decitabine (DAC), at non-cytostatic/cytotoxic doses causes upregulation of multiple chemokines, specifically Cxcl10. 200nM DAC for 48 hours increased Cxcl10 transcription 22-fold (95% CI 20.6-21.1-fold, p=0.0001, values normalized to Gapdh control), and protein levels in supernatant three-fold (t test p<0.0001). At this dose, DNTM1, the target enzyme of DAC, is downregulated on Western-blot analysis, and the methyl-cytosine/cytosine ratio decreases significantly (means compared with t test, p =0.002). Other statistically significant upregulated chemokine genes are Cxcl1 (p=0.002), Cxcl3 (p<0.001), Cxcl4 (p<0.001), Cxcl5 (p=0.03), and Ccl4 (p=0.01). Conclusions: Abrogation of DNA methylation with DAC in Trp53-/- ID8 cells induces an increase in the chemokine cxcl10, at both transcriptional and protein level. This provides a robust control for a medium-throughput screening of other epigenetic modifiers that are still at an early drug development stage, such as probes against bromodomains, methyltransferases, and demethylases. Such screening can unmask novel epigenetic mechanisms involved in immune-related gene transcription and offer new ways to potentiate immunotherapy in ovarian cancer. Citation Format: Pavlina Spiliopoulou, Josephine Walton, Suzanne Dowson, Alex Binks, Oliver Maddocks, Peter Adams, Iain McNeish. Epigenetic modification of ovarian cancer immunogenicity. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr A37.

Abstract B47: Rgnef (p190RhoGEF/Arhgef28) loss impairs ovarian tumor metastatic growth

Abstract Increased activation of FAK and Rho GTPase regulatory pathways is associated with shorter survival in patients with high-grade serous ovarian carcinoma (HGSOC). However, the key mediators of these signaling events in HGSOC remain unknown. We have previously shown that the Rho guanine nucleotide exchange factor Rgnef (also named p190RhoGEF or Arhgef28) activates FAK as well as RhoA GTPase in mouse fibroblasts. Here we find that Rgnef protein expression is elevated in Stage 3-4 HGSOC and that Rgnef knockout prevents ovarian tumor spheroid growth in vitro and in vivo. We isolated ascites-associated murine ID8 cells to generate a more aggressive cell line, termed ID8-IP. ID8-IP cells exhibit higher Rgnef and FAK expression than parental ID8 cells. CRISPR/Cas9-induced knockout of Rgnef in ID8-IP cells does not alter 2D growth as compared to Rgnef-KO cells re-expressing GFP-Rgnef. However, Rgnef loss significantly decreased growth as spheroids in a 3D Matrigel-on-Top assay. At five weeks following intraperitoneal injection into syngeneic C57Bl/6 mice, ID8-IP Rgnef-KO cells form significantly fewer ascites-associated cells, as well as fewer metastatic lesions on the peritoneal wall. Notably, ID8-IP Rgnef-KO cells display lower FAK and ERK1/2 phosphorylation. These studies demonstrate that Rgnef loss impedes metastatic growth in the peritoneal cavity, and suggest that an integrin-mediated Rgnef-FAK linkage facilitates ovarian tumor metastasis. Citation Format: Elizabeth G. Kleinschmidt, Isabelle Tancioni, Kristin Taylor, Carlos Osterman-Diaz, Nichol L. G. Miller, Shulin Jiang, David D. Schlaepfer. Rgnef (p190RhoGEF/Arhgef28) loss impairs ovarian tumor metastatic growth. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B47.

Correction: Ruxolitinib sensitizes ovarian cancer to reduced dose Taxol, limits tumor growth and improves survival in immune competent mice.

[This corrects the article DOI: 10.18632/oncotarget.21541.].

Wounding promotes ovarian cancer progression and decreases efficacy of cisplatin in a syngeneic mouse model

BackgroundPrimary cytoreductive surgery followed by adjuvant chemotherapy is the standard treatment for advanced epithelial ovarian cancer. The average interval between surgery and chemotherapy initiation is approximately 4-weeks at most centers; however, since surgery may accelerate residual tumor growth, a shorter interval may be more beneficial.MethodsThe murine ID8 cell model of ovarian cancer was used to examine the efficacy of cisplatin treatment administered perioperatively or 7 days after surgical wounding. Luciferase-expressing cells ID8 cells were injected intraperitoneally (i.p.) into female C57/Bl6 mice. Fourteen days post-injection, animals received an abdominal incision or anesthesia alone and received i.p. cisplatin either on the surgical day or 7 days later, or received no chemotherapy. Additional animals received cisplatin 28 days after wounding for comparison.ResultsAbdominal tumor mass increased 2.5-fold in wounded vs. unwounded animals as determined by bioluminescent in vivo tumor imaging. Cisplatin administered on the day of wounding decreased tumor burden by 50%, as compared to 90% in unwounded animals. Cisplatin on day 7 or day 28 decreased tumor burden by 80 and 37% respectively.ConclusionsSurgical wounding increases ovarian tumor mass and decreases perioperative cisplatin efficacy in this animal model. Administration of cisplatin 1 week after surgery was more effective than cisplatin administered perioperatively or 4 weeks after surgery.

Abstract 5202: Pigment epithelium-derived factor promotes tumor dissemination of ovarian cancer cells through an interaction with peritoneal immune system

Abstract Ovarian cancer is a gynecological malignancy with a high mortality rate. Patients with ovarian cancer are diagnosed at an advanced stage of the disease with massive peritoneal dissemination. However, the underlying mechanism by which ovarian cancer cells preferentially colonize the omentum is still poorly understood. In this study, we have identified the factors and mechanisms which promote ovarian cancer dissemination by regulating peritoneal immune system. First, we established a mouse ovarian cancer cell line, ID8GO2, with an increased ability to disseminate in the peritoneal cavity by in vivo passage of ID8 cells in B6J mice. To determine the candidate genes that drive the dissemination, we examined the differences in gene expression profiles between two cell lines. Expression of the candidate genes in human ovarian cancer tissues and their correlation with the clinical outcomes of patients were also analyzed using public database. We found that pigment epithelium-derived factor (PEDF) was the most relevant gene associated with poor prognosis. To clarify whether PEDF contributes to peritoneal dissemination, ID8 cells were retrovirally transduced with mouse PEDF (ID8-PEDF) or empty vector (ID8-EV) and transplanted into the syngeneic mouse peritoneal cavity. All mice transplanted with ID8-PEDF cells developed intraperitoneal dissemination more rapidly and the overall survival time was significantly shorter than that in mice transplanted with ID8-EV cells. Moreover, ID8-PEDF cells survived longer in the peritoneal cavity. We further found that ID8 cells originally consisted of clones with varied PEDF expression. Transplantation of the PEDF-high clones resulted in faster development of intraperitoneal dissemination and shorter overall survival than that of the PEDF-low clones. These findings suggest that PEDF contributes to peritoneal dissemination of ovarian cancer cells, and cells with high initial PEDF expression are selected during dissemination. Next, to clarify the mechanism underlying the role of PEDF in peritoneal dissemination, intraperitoneal immune cell subsets in tumor bearing mice were analyzed. Peritoneal macrophages in mice transplanted with ID8-PEDF cells displayed alternative activated macrophage phenotype (F4/80+ CD206+) and high IL10 expression. Interestingly, at later time point, regulatory T and regulatory B cells were induced in the peritoneal cavity. Collectively, these findings suggest that PEDF plays an important role in the peritoneal dissemination of ovarian cancer cells potentially by regulating macrophages and regulatory lymphocytes to evade the peritoneal immune system. Citation Format: Sayaka Ueno, Eiji Sugihara, Tamotsu Sudo, Hideyuki Saya. Pigment epithelium-derived factor promotes tumor dissemination of ovarian cancer cells through an interaction with peritoneal immune system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5202.

Abstract 626: Bromodomain inhibition in ovarian cancer and the tumor microenvironment to improve PARP inhibitor response

Abstract Background: Ovarian cancer is the most lethal gynecologic malignancy. While women with BRCA-deficient tumors show sensitivity to PARP inhibitors (PARPi), new treatment options are needed for PARPi-resistant tumors. An emerging strategy to improve PARPi response is combination therapy with epigenetic drugs. A newly recognized epigenetic drug target in ovarian cancer is the bromodomain and extraterminal (BET) protein family. BET proteins such as BRD4 promote oncogenic transcription of progrowth and survival genes, including the established link between inflammation and cancer, nuclear factor-kappaB (NF-κB). A complementary strategy to targeting cancer cells with cytotoxic drugs is to activate normal immune processes in the tumor microenvironment (TME). In syngeneic mouse ovarian cancer models, we have shown that M2-like protumor macrophages are a prominent component of the TME, and that NF-κB inhibition reduces the M2 population. Thus, BET inhibitors (BETi) have the potential to induce transcriptional reprogramming in both tumors and macrophages for therapeutic benefit. Objective: To determine the cellular and molecular effects of combining BETi and PARPi in mouse ovarian cancer and peritoneal macrophage cell lines. Methods: Cultured wild-type and CRISPR-modified (TP53 and TP53/BRCA2 knockout) ID8 mouse ovarian cancer cells, and PMJ2-PC mouse peritoneal macrophages, were treated with vehicle, the PARPi olaparib, the first-in-class BETi JQ1 or the JQ1/olaparib combination for 24-72h. Sulforhodamine B (SRB) assays assessed cell growth. Immunofluorescence assays assessed adherent cell number, DNA damage (pH2AX) and cell cycle indices. Protein levels of pH2AX and the apoptosis marker cleaved PARP were assessed by Western blot. NF-κB activity was measured by luciferase assays of a transiently transfected reporter plasmid. Results: Combined JQ1 and olaparib treatment synergistically reduced cell growth in SRB assays in wild-type and TP53 knockout ID8 cells. TP53/BRCA2 knockout cells showed greater responses to PARPi alone and no synergism was observed. Consistent with these results, the JQ1/olaparib combination cooperatively reduced the number of adherent cells and cells in S phase, and increased the G0/G1 population, DNA damage and apoptosis. In contrast, the drug combination had minimal effects on DNA damage or apoptosis in PMJ2-PC macrophages, while NF-κB activity was reduced in both cancer cells and macrophages. Conclusions: BETi sensitize mouse ovarian cancer cells to the cytotoxic effects of PARPi. Combined drug treatment also has potential to inhibit NF-κB in both cancer cells and macrophages. Our novel immunomodulatory strategy will be tested in ID8 syngeneic ovarian cancer models. We believe BETi combination treatment could expand the use of PARPi in ovarian cancer patients, with the potential to benefit a substantial number of women with this devastating disease. Citation Format: Andrew J. Wilson, Alyssa Hoover, Whitney Harris, Esther Liu, Dineo Khabele, Fiona Yull. Bromodomain inhibition in ovarian cancer and the tumor microenvironment to improve PARP inhibitor response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 626.

Induction of DNA Damage in Ovarian Cancer Induces Type I Interferon Signaling

ObjectiveEpithelial ovarian cancer patients initially respond to cytotoxic chemotherapy, however the majority develop recurrent disease that is resistant to current treatments and 5‐year survival is less than 50%. Immunotherapies have shown promise in some solid tumors, yet response rates in ovarian cancer are only 10–15%. We therefore sought to identify new approaches to increase ovarian cancer tumor immunogenicity with the goal of improving immunotherapy response rates. We previously found that the DNA damage repair protein DEK is overexpressed in ovarian cancer cell lines and primary tumors, and that decreasing DEK levels induces DNA damage and apoptotic cell death. Cytoplasmic DNA from damaged cells can activate the DNA‐sensing protein STING, resulting in induction of the type I interferon (IFN‐I) signaling pathway that facilitates antigen‐presenting cell (APC) maturation and cross‐priming of T cells. Therefore, our objective was to determine if decreasing DEK levels induces IFN‐I signaling to enhance ovarian cancer immune signaling.MethodsWe developed a new machine learning tool, Fast and Robust Deconvolution of Expression Profiles (FARDEEP) to characterize the landscape of tumor‐infiltrating lymphocytes (TIL) in 299 high grade serous ovarian cancers from the Cancer Genome Atlas (TCGA). We then performed RNA‐Seq analysis on OVCAR8 and OVCAR3 ovarian cancer cell lines with stable expression of shRNA targeting DEK (shDEK) or control shRNA. Gene expression patterns were analyzed by Gene Set Enrichment Analysis and confirmed by RT‐PCR. In addition, IFN‐I signature transcripts were further validated by RT‐PCR after ovarian cancer cell lines were infected with lentivirus expressing shDEK or control. ID8 cells from an immunocompetent ovarian cancer mouse model were analyzed by RT‐PCR for IFN‐I signatures after being transfected with siRNA targeting Dek or control without or with Sting expression plasmid.ResultsFARDEEP analysis demonstrated that elevated levels of IFN‐I signature genes including CXC chemokines CXCL9 and CXCL10 are correlated with TIL subsets essential for anti‐tumor immunity, indicating IFN‐I signaling is important in preventing ovarian cancer immune escape. RNA‐Seq in ovarian cancer cell lines revealed that decreasing DEK levels resulted in an upregulation of interferon response signals. Further evaluation of IFN‐I signaling demonstrated that decreasing DEK levels enhanced transcription of IFN‐I signature genes, including interferon beta 1 (IFNB1), CXCL9 and CXCL10. In addition, Dek‐deficiency in ID8 cells enhanced Sting‐mediated induction of Ifnb1, Cxcl9 and Cxcl10.ConclusionOur TIL deconvolution findings support the hypothesis that IFN‐I signaling is pivotal for the immunogenicity of ovarian cancer. Decreasing DEK expression induces DNA damage and resultant IFN‐I signaling. Further studies are underway with the ID8 ovarian cancer mouse model system. Our results suggest a potential approach to increase immune signaling in the tumor microenvironment and thus improve response rates to immunomodulatory therapies in ovarian cancer.Support or Funding InformationMichigan Ovarian Cancer Alliance Geri Fournier Ovarian Cancer Research AwardsThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

FAK-ERK activation in cell/matrix adhesion induced by the loss of apolipoprotein E stimulates the malignant progression of ovarian cancer

BackgroundExtracellular matrix (ECM) is a mediator of tumor progression. However, whether the alterations of the intraperitoneal ECM prior to tumor establishment affects the malignant progression of ovarian cancer remains elusive.MethodsApolipoprotein (ApoE) knock-out mice was used to analyze the intraperitoneal ECM alterations by quantification of the major components of ECM. ID8 cells were implanted in vivo to generate allografts and human ovarian cancer cell lines were characterized in vitro to assess the effects of ECM alterations on the malignant progression of ovarian cancer. Adhesion assay, immunochemistry, cytokines profile, proliferation assay, transwell invasion assay and western blot were used to determine the malignant phenotype of ovarian cancer cells.ResultsApoE loss induced increased ECM deposition, which stimulated the adhesions of ovarian cancer cells. The adhesion-mediated focal adhesion kinase (FAK) signaling enhanced the invasive behaviors of ovarian cancer cells through activation of a ERK-MMP linkage. This ECM-induced signaling cascade was further confirmed in human ovarian cancer cell lines in vitro. Furthermore, reversal of the ECM accumulation with BAPN or abrogation of adhesion-induced ERK activation in ovarian cancer cells with MEK inhibitors (MEKi) was found to effectively delay ovarian cancer progression.ConclusionsThese findings identify the FAK-ERK activation in cell/matrix adhesion in the malignant progression of ovarian cancer and the efficiency of BAPN or MEKi for tumor suppression, providing an impetus for further studies to explore the possibility of new anticancer therapeutic combinations.

3D Co-culture System of Tumor-associated Macrophages and Ovarian Cancer Cells.

Ovarian cancer is fairly unique in that ovarian carcinoma cells can detach and spread directly through peritoneal cavity. It has been unclear, however, how detached cancer cells survive in the peritoneum and form spheroid structure. We have recently reported that there is a strong correlation between Tumor-associated macrophages (TAMs)-associated spheroid and clinical pathology of ovarian cancer, and that TAMs promote spheroid formation and tumor growth at early stages of transcoelomic metastasis in orthotopic mouse models. We have established an in vitro spheroid formation assay using a 3D co-culture system in which mouse GFP+F4/80+CD206+ TAMs isolated from spheroids of ovarian cancer-bearing donor tomatolysM-cre mice were mixed with ID8 cells (TAM:ID8 at a ratio of 1:10) in medium containing 2% Matrigel and seeded onto the 24-well plate precoated with Matrigel. As transcoelomic metastasis is also associated with many other cancers such as pancreatic and colon cancers, TAM-mediated spheroid formation assay would provide a useful approach to define the molecular mechanism and therapeutic targets for ovarian cancer and other transcoelomic metastasis cancers.

A cancer vaccine with dendritic cells differentiated with GM-CSF and IFNα and pulsed with a squaric acid treated cell lysate improves T cell priming and tumor growth control in a mouse model.

Introduction: Ovarian cancer is one of the most lethal gynecologic cancers. Relapses after remission are common, hence novel strategies are urgently needed. Our group has previously developed a vaccination approach based on dendritic cells pulsed with HOCl-oxidized tumor lysates. Here we investigate the improvement of this vaccine strategy using squaric acid treatment of cancer cells during tumor lysate preparation and by differentiating dendritic cells in the presence of GM-CSF and IFNα. Methods: Induction of cell death by squaric acid treatment was assessed with propidium iodide (PI) and Annexin V in ID8 tumor cells. High mobility group box 1 (HMGB1) immunogenic status was analyzed using a western blot-based method, as previously described. For immunological tests, ID8 cells expressing ovalbumin (ova-ID8) were treated with squaric acid before cell lysis. DCs prepared with the canonical GM-CSF and IL-4 differentiation cocktail or IFNα and GM-CSF were pulsed with tumor cell lysates and further matured in the presence of IFNγ and LPS (4-DCs and α-DCs respectively). DCs were then used in co-culture assays with ova-specific T cells and IFNγ and IL-4 secretion measured by ELISA. DC phenotypes were characterized by FACS. Finally, DCs were tested in an ovarian cancer mouse model measuring body weight and animal survival. Results: Squaric acid treatment of mouse ovarian cancer cells induced tumor cell death as well as preserve HMGB1, a crucial Damage-associated molecular pattern (DAMP) signal, in its active reduced form. Squaric acid treatment of ID8-ova cells increased IFNγ and decreased IL-4 production from ova-specific T cells in co-culture experiments, promoting a more immunogenic cytokine secretion pattern. DCs differentiated in the presence of IFNα induced a considerable decrease in IL-4 production compared to canonical 4-DCs, without affecting IFNγ release. DC phenotyping demonstrated a more mature and immunogenic phenotype for IFNα-differentiated DCs. Vaccination in tumor-bearing mice showed that IFNα-differentiated DCs pulsed with squaric acid-treated lysates were the most potent at delaying tumor growth, improving animal survival. Conclusion: We identified squaric acid as a novel immunogenic treatment of tumor cells for cancer vaccines particularly efficient in prolonging animal survival when used in combination with IFNα-differentiated DCs. These promising results support future efforts for the clinical translation of this approach.

Upregulation of IGF1 by tumor-associated macrophages promotes the proliferation and migration of epithelial ovarian cancer cells.

Ovarian cancer (OC), of which epithelial ovarian cancer (EOC) is the most common, is the deadliest gynecological tumor because of the difficulties in detection at early stages, and metastasis and chemoresistance at advanced stages. Tumor-associated macrophages (TAMs) differentiate through alternative pathways and play important roles in tumor growth and metastasis. However, the underlying mechanism remains unclear. Here, we established a mouse TAM model using bone marrow monocytes and conditioned medium (CM) of TAMs to culture ID8 mouse EOC cells. The results showed that TAMCM accelerated the proliferation and migration of ID8 cells. In a previous study, gene chip analysis showed that human TAMs expressed significantly higher levels of insulin-like growth factor‑1 (IGF1) than undifferentiated M0 myeloid cells. In the present study, we observed that the IGF1 level was higher in human EOC specimens than that in benign ovarian tumor specimens, and further analysis showed that a higher level of IGF1 was related to more advanced clinical stage and liver metastasis. Therefore, we hypothesized that TAMs may accelerate the proliferation and migration of EOC cells by upregulating IGF1. As expected, increased IGF1 expression at both the mRNA and protein levels was observed in ID8 cells cultured with TAMCM, whereas blockade of the IGF1 pathway in ID8 cells with an IGF1 neutralizing antibody effectively reversed the promotion of proliferation and migration. Finally, we inhibited the phosphorylation of insulin-like growth factor‑1 receptor (IGF1R) and its downstream molecules Akt and Erk with the IGF1R inhibitor linsitinib, and observed that the treatment effectively suppressed the proliferation and migration of ID8 cells exposed to TAMCM. Thus, we demonstrated that TAMs may promote the growth and metastasis of EOC via the activation of the IGF1 pathway; thus, targeting the IGF1 pathway may be promising for EOC therapy.

CRISPR/Cas9-derived models of ovarian high grade serous carcinoma targeting Brca1, Pten and Nf1, and correlation with platinum sensitivity

Transplantable murine models of ovarian high grade serous carcinoma (HGSC) remain an important research tool. We previously showed that ID8, a widely-used syngeneic model of ovarian cancer, lacked any of the frequent mutations in HGSC, and used CRISPR/Cas9 gene editing to generate derivatives with deletions in Trp53 and Brca2. Here we have used one ID8 Trp53−/− clone to generate further mutants, with additional mutations in Brca1, Pten and Nf1, all of which are frequently mutated or deleted in HGSC. We have also generated clones with triple deletions in Trp53, Brca2 and Pten. We show that ID8 Trp53−/−;Brca1−/− and Trp53−/−;Brca2−/− cells have defective homologous recombination and increased sensitivity to both platinum and PARP inhibitor chemotherapy compared to Trp53−/−. By contrast, loss of Pten or Nf1 increases growth rate in vivo, and reduces survival following cisplatin chemotherapy in vivo. Finally, we have also targeted Trp53 in cells isolated from a previous transgenic murine fallopian tube carcinoma model, and confirmed that loss of p53 expression in this second model accelerates intraperitoneal growth. Together, these CRISPR-generated models represent a new and simple tool to investigate the biology of HGSC, and the ID8 cell lines are freely available to researchers.

Ruxolitinib sensitizes ovarian cancer to reduced dose Taxol, limits tumor growth and improves survival in immune competent mice.

BackgroundChemotherapy initially reduces the tumor burden in patients with ovarian cancer. However, tumors recur in over 70% of patients, creating the need for novel therapeutic approaches.MethodsWe evaluated Ruxolitinib, an FDA-approved JAK 1/2 kinase inhibitor, as a potential adjunctive therapy for use with low-dose Taxol (Paclitaxel) by assessing the impact on in vitro proliferation and colony formation of ID8 cells or human TOV-112D ovarian cancer cells, as well as flow cytometric measurement of surface markers associated with cellular stress and stemness by ID8 cells. The syngeneic ID8 murine model of ovarian cancer was used to assess the impact of Ruxolitinib and Taxol, individually and in combination, on tumor initiation and growth, as well as capacity to extend survival.ResultsRuxolitinib (≤10 μM) sensitized both ID8 and TOV-112D cells to low concentrations of Taxol (≤5 nM), limiting cell proliferation and colony formation in vitro. Mechanistically, we demonstrated that Taxol induced expression of stress and stemness markers including GRP78 and CD133 was significantly reduced by addition of Ruxolitinib. Finally, we demonstrated that a single administration of a low-dose of Taxol (10 mg/Kg) together with daily Ruxolitinib (30 mg/Kg; which is equivalent to plasma concentrations of ∼ 0.01 μM steady-state) limited ID8 tumor growth in vivo and significantly extended median survival up to 53.5% (median 70 v 107.5 days) as compared to control mice.ConclusionTogether, these data support the use of Ruxolitinib in combination with low-dose Taxol as a therapeutic approach with the potential for improved efficacy and reduced side effects for patients with recurrent ovarian cancer.

Efficacy of Lycium barbarum polysaccharide and synergism with paclitaxel/cisplatin in ovarian cancer in mice

Purpose: To determine the efficacy of Lycium barbarum polysaccharide (LBP) in ovarian cancer, and the synergistic effect when used in combination with paclitaxel/cisplatin (PXT∕DDP). Methods: ID-8 cells were injected subcutaneously into 5 groups of female C57BL/6 mice (5 mice/group): control (Con), chemotherapy (CH, PTX/DDP), combination therapy 1 (co-CH1, PTX/DDP + 50 mg/kg LBP), combination therapy 2 (co-CH2, 100 mg/kg LBP) and combination therapy 3 (co-CH3, 150 mg/kg LBP). Tissue morphological changes were monitored by hematoxylin and eosin (H&E) staining. Protein and mRNA levels of Keap1, Nrf2) and heme oxygenase-1 (HemO-1) were analyzed by western blotting and real-time polymerase chain reaction (PCR), as applicable. Results: Growth rate and volume of tumors were significantly reduced in the chemotherapy and combination therapy groups, while organ index increased significantly in co-CH group. Morphological structure of tumor, liver and kidney became normal after combination therapy. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), uric acid (UA), creatinine (Cr) and blood urea nitrogen (BUN) were significantly decreased in co-CH group relative to CH group. Lymphocytes, monocytes (MNC), neutrophils, basophils and eosnophils were significantly regulated by combination therapy. In CH and co-CH1-3 groups, the mRNA and protein levels of Keap1, HO-1 and Nrf2 were significantly increased relative to those of control mice. Conclusion: LBP in combination with PXT∕DDP enhances the efficacy of the latter, and reduced its toxicity when used for the treatment of ovarian malignant tumor in mice, by activating Keap1/Nrf2 pathway and promoting immunity. Keywords: Lycium barbarum polysaccharide (LBP), Paclitaxel/Cisplatin, Keap1/Nrf2 pathway, Cytotoxicity

WEE1 inhibition by MK1775 as a single-agent therapy inhibits ovarian cancer viability.

Wee1-like protein kinase (WEE1) physiologically serves a key function in maintaining the integrity of the cell genome through mediating the activation of cyclin-dependent kinase (CDK)1 and CDK2. Increased expression of WEE1 has been associated with the poor prognosis of patients with ovarian cancer. The present study aimed at examining the in vitro and in vivo antitumor activity of MK1775, a potent pharmacological inhibitor of WEE1, as a single agent against ovarian cancer cells. The cytotoxicity of MK1775 was examined in a panel of tumor cells using MTT in vitro. Subsequently, a cell apoptosis assay was performed in ovarian cancer SKOV3 and ID8 cells to characterize the function of MK1775 in tumor cell apoptosis, under either wild-type tumor protein 53 (p53) or null p53 status. In addition, cell cycle analysis and a western blot analysis were performed to validate the effect of MK1775 on cell cycle progression and to elucidate the underlying molecular mechanism of cell death. Finally, the in vivo antitumor efficacy of MK1775 as a single agent at a clinical well-tolerated dose was determined. A dose-dependent inhibitory effect of MK1775 on tumor cell viability was determined in distinct cell lines, including B16F10, LLC1, BPS1, EG7, ID8 and SKOV3. Results from the cell cycle analysis and western blotting indicated that MK1775 abrogated the G2/M checkpoint through inhibiting the phosphorylation of CDK1 and inducing the apoptosis of ovarian cancer cells that lacked mutations in p53 and breast cancer 1 (BRCA1). Additionally, a significant antitumor effect of MK1775 was observed in C57BL/6 mice bearing syngeneic ID8 ovarian tumors. The results of the present study supported the use of MK1775 as a monotherapy agent in ovarian cancer. MK1775 was effective at inducing mitotic catastrophe, independent of p53 and BRCA1 mutations. Therefore, WEE1 inhibition by MK1775 requires additional investigation to identify novel combination approaches in ovarian cancer therapy with the current DNA damaging agents, including irradiation treatment and cell cycle checkpoint inhibitors.

Abstract 947: CXCR4 in combination with immune check point inhibition in ovarian cancer mouse model demonstrates potential for novel therapeutic strategies

Abstract Chemokine CXCL12 and its receptor CXCR4 are the most highly expressed chemokine axis in serous ovarian cancer. CXCR4 promotes tumor growth, angiogenesis, and metastasis. High CXCR4 expression is associated with poor survival, making it an attractive therapeutic target. The objective of this study was to establish an immune competent murine ovarian cancer model with high CXCR4 expression and to test single agent CXCR4 blockade and combination therapy to optimize emerging treatment strategies for future clinical trials. CXCR4 expression was evaluated by flow cytometry in ID8, ID8-VEGF, IE9-MP1, BR5, BR5-Akt, BR5-C2k, and BR5-Kras mouse ovarian cancer cell lines as well as IE9-MP1 tumor samples. Subsequently an exploratory study was undertaken utilizing the ID8 immune competent mouse model to assess the efficacy of AMD3100, the only commercially available CXCR4 inhibitor, alone and in combination with bevacizumab and anti-PD-1. Immune analysis of circulating lymphocytes by flow cytometry was performed during treatment to monitor changes of immune cell subsets. Surface expression of CXCR4 receptor was minimal in ID8 (1.6%), ID8-VEGF (0.9%), IE9-MP1 (1.8%), BR5 (0.9%), BR5-Akt (1.2%), BR5-C2k (2.3%), and BR5-Kras (1.1%), however intracellular staining revealed widespread CXCR4 expression in ID8 (99.6%), ID8-VEGF (99.7%) BR5 (96.7%), BR5-Akt (94.3%), BR5-C2k (98.2%), and BR5-Kras (98.7%) cell lines. Using the ID8 intraperitoneal ovarian cancer mouse model in C57BL/6J mice, treatment with immunotherapy significantly increased cell surface expression of CXCR4 from 2% in the control group to 79.6-91.8% in the treatment group. Treatment with AMD3100 as a single agent showed no improvement in survival over control. However, AMD3100 in combination with anti-PD-1 therapy significantly improved survival. The addition of bevacizumab demonstrated no further survival benefit and bevacizumab as a single agent showed no improvement in survival over control, either alone or in combination with anti-PD-1. Analysis of circulating lymphocytes revealed a trend toward higher CD4 to CD8 ratio in mice who were treated with anti-PD1 therapy. Targeting the CXCL12-CXCR4 axis in combination with other immunotherapies such as immune checkpoint inhibitors is a novel therapeutic strategy which may provide benefit over single-agent immunotherapy and warrant investigation in a clinical trial. Citation Format: Kristen Starbuck, Robert McGray, Samar Masoumi-Moghaddam, Ariel Francois, Kunle Odunsi, Emese Zsiros. CXCR4 in combination with immune check point inhibition in ovarian cancer mouse model demonstrates potential for novel therapeutic strategies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 947. doi:10.1158/1538-7445.AM2017-947