Tracking NF-κB activity in tumor cells during ovarian cancer progression in a syngeneic mouse model

NF-κB signaling pathway in tumor microenvironment

The genesis and progression of tumors are multifaceted processes influenced by genetic mutations within the tumor cells and the dynamic interplay with their surrounding milieu, which incessantly impacts the course of cancer. The tumor microenvironment (TME) is a complex and dynamic entity that encompasses not only the tumor cells but also an array of non-cancerous cells, signaling molecules, and the extracellular matrix. This intricate network is crucial in tumor progression, metastasis, and response to treatments. The TME is populated by diverse cell types, including immune cells, fibroblasts, endothelial cells, alongside cytokines and growth factors, all of which play roles in either suppressing or fostering tumor growth. Grasping the nuances of the interactions within the TME is vital for the advancement of targeted cancer therapies. Consequently, a thorough understanding of the alterations of TME and the identification of upstream regulatory targets have emerged as a research priority. NF-κB transcription factors, central to inflammation and innate immunity, are increasingly recognized for their significant role in cancer onset and progression. This review emphasizes the crucial influence of the NF-κB signaling pathway within the TME, underscoring its roles in the development and advancement of cancer. By examining the interactions between NF-κB and various components of the TME, targeting the NF-κB pathway appears as a promising cancer treatment approach.

Loss of B1 and marginal zone B cells during ovarian cancer

Recent advances in immunotherapy have not addressed the challenge presented by ovarian cancer. Although the peritoneum is an "accessible" locus for this disease there has been limited characterization of the immunobiology therein. We investigated the ID8-C57BL/6J ovarian cancer model and found marked depletion of B1 cells from the ascites of the peritoneal cavity. There was also selective loss of the B1 and marginal zone B cell subsets from the spleen. Immunity to antigens that activate these subsets validated their loss rather than relocation. A marked influx of myeloid-derived suppressor cells correlated with B cell subset depletion. These observations are discussed in the context of the housekeeping burden placed on innate B cells during ovarian cancer and to foster consideration of B cell biology in therapeutic strategies to address this challenge.

OSR1 downregulation indicates an unfavorable prognosis and activates the NF-κB pathway in ovarian cancer

BACKGROUND

Odd-skipped related 1 (OSR1) has been reported as a tumor suppressor gene in various malignant tumors. The mechanism through which OSR1 regulates ovarian cancer (OC) progression remains unclear.

MATERIALS AND METHODS

Immunohistochemistry was utilized to evaluate OSR1 expression in patients with ovarian cancer. We investigated the association between clinicopathological parameters and OSR1 expression in OC patients and the influence of OSR1 expression on patient survival and prognosis. OC cells with OSR1 overexpression or knockdown were established and validated using Western blot and Quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The influence of OSR1 on the NF-κB pathway was examined by analyzing the p-IκBα, IκBα, p65, and p-p65 protein expression. In vitro assays, such as cell cycle assay, Cell Counting Kit-8 (CCK-8), transwell invasion assay, wound healing migration assay, enzyme-linked immunoassay (ELISA), and Annexin V/PI flow cytometry apoptosis assay, were conducted to explore the effect of OSR1 knockdown or dual inhibition of OSR1 and the NF-κB pathway on OC malignant biological behavior.

RESULTS

OSR1 expression was downregulated in OC tissues, with significant associations observed between its expression and The International Federation of Gynecology and Obstetrics (FIGO) stage and tissue differentiation. Low OSR1 expression in OC patients correlated with reduced overall survival (OS) rates and poor prognosis. In vitro, experiments confirmed a negative correlation between OSR1 expression and NF-κB pathway activity. OSR1 knockdown facilitated OC cell malignant biological behavior, while the NF-κB pathway inhibitor (Bay 11-0782) reversed the impacts of OSR1 knockdown on cell proliferation, migration, invasion, and apoptosis.

CONCLUSION

Our findings indicate that OSR1 is downregulated and associated with OC prognosis. OSR1 suppresses NF-κB pathway activity and inhibits OC progression by targeting the NF-κB pathway.

Prognostic significance of natural products against multidrug tumor resistance

Cancer is a pervasive, constantly evolving, and significant public health concern. The number of new cancer cases has risen dramatically in the last decades, making it one of the top causes of poor health and mortality worldwide. Although various treatment strategies, including surgery, radiation, and pharmaceutical therapies, have evolved into more sophisticated, precise methods, there is not much improvement in the cancer-related death toll. Consequently, natural product-based therapeutic discoveries have recently been considered an alternative approach. According to an estimate, one-third of the top twenty medications in today's market have a natural plant-product-based origin. Accordingly, primary prevention is an essential component of worldwide cancer control. This review provides an overview of the mechanisms of action of bioactive ingredients in natural dietary products that may contribute to the prevention and management of multiple malignancies.

Modulating multidrug resistance to drug-based antitumor therapies through NF-κB signaling pathway: mechanisms and perspectives

INTRODUCTION

Despite the advances made in cancer treatment in the past decades, therapeutic efficacy is still quite challenging, partially due to the emergence of multidrug resistance (MDR). It is crucial to decipher the underlying mechanisms of resistance in order to develop new therapeutic strategies for cancer patients. Previous studies have shown that activation of nuclear factor-κB (NF-κB) plays key roles in various cellular processes including proliferation, anti-apoptosis, metastasis, invasion, and chemoresistance.

AREAS COVERED

In this review, we conduct an integrated analysis of the evidence suggesting the vital roles of the NF-κB signaling pathway in MDR during chemotherapy, immunotherapy, endocrine, and targeted therapy. A literature search was performed on NF-κB and drug resistance in PubMed up to February 2023.

EXPERT OPINION

This review summarizes that the NF-κB signaling pathway exhibits a crucial role in enhancing drug resistance in chemotherapy, immunotherapy, endocrine, and targeted therapy. The application of combination therapy with existing antineoplastic drugs and a safe NF-κB inhibitor could become a promising strategy in cancer treatment. A better understanding of the pathway and mechanisms of drug resistance may help exploit safer and more effective NF-κB-targeting agents for clinical use in the future.

Compound C Inhibits Ovarian Cancer Progression via PI3K-AKT-mTOR-NFκB Pathway

Epithelial Ovarian cancer (OvCa) is the leading cause of death from gynecologic malignancies in the United States, with most patients diagnosed at late stages. High-grade serous cancer (HGSC) is the most common and lethal subtype. Despite aggressive surgical debulking and chemotherapy, recurrence of chemo-resistant disease occurs in ~80% of patients. Thus, developing therapeutics that not only targets OvCa cell survival, but also target their interactions within their unique peritoneal tumor microenvironment (TME) is warranted. Herein, we report therapeutic efficacy of compound C (also known as dorsomorphin) with a novel mechanism of action in OvCa. We found that CC not only inhibited OvCa growth and invasiveness, but also blunted their reciprocal crosstalk with macrophages, and mesothelial cells. Mechanistic studies indicated that compound C exerts its effects on OvCa cells through inhibition of PI3K-AKT-NFκB pathways, whereas in macrophages and mesothelial cells, CC inhibited cancer-cell-induced canonical NFκB activation. We further validated the specificity of the PI3K-AKT-NFκB as targets of compound C by overexpression of constitutively active subunits as well as computational modeling. In addition, real-time monitoring of OvCa cellular bioenergetics revealed that compound C inhibits ATP production, mitochondrial respiration, and non-mitochondrial oxygen consumption. Importantly, compound C significantly decreased tumor burden of OvCa xenografts in nude mice and increased their sensitivity to cisplatin-treatment. Moreover, compound C re-sensitized patient-derived resistant cells to cisplatin. Together, our findings highlight compound C as a potent multi-faceted therapeutic in OvCa.

Stimulating TAM-mediated anti-tumor immunity with mannose-decorated nanoparticles in ovarian cancer

BACKGROUND

Current cancer immunotherapies have made tremendous impacts but generally lack high response rates, especially in ovarian cancer. New therapies are needed to provide increased benefits. One understudied approach is to target the large population of immunosuppressive tumor-associated macrophages (TAMs). Using inducible transgenic mice, we recently reported that upregulating nuclear factor-kappaB (NF-κB) signaling in TAMs promotes the M1, anti-tumor phenotype and limits ovarian cancer progression. We also developed a mannose-decorated polymeric nanoparticle system (MnNPs) to preferentially deliver siRNA payloads to M2, pro-tumor macrophages in vitro. In this study, we tested a translational strategy to repolarize ovarian TAMs via MnNPs loaded with siRNA targeting the inhibitor of NF-κB alpha (IκBα) using mouse models of ovarian cancer.

METHODS

We evaluated treatment with MnNPs loaded with IκBα siRNA (IκBα-MnNPs) or scrambled siRNA in syngeneic ovarian cancer models. ID8 tumors in C57Bl/6 mice were used to evaluate consecutive-day treatment of late-stage disease while TBR5 tumors in FVB mice were used to evaluate repetitive treatments in a faster-developing disease model. MnNPs were evaluated for biodistribution and therapeutic efficacy in both models.

RESULTS

Stimulation of NF-κB activity and repolarization to an M1 phenotype via IκBα-MnNP treatment was confirmed using cultured luciferase-reporter macrophages. Delivery of MnNPs with fluorescent payloads (Cy5-MnNPs) to macrophages in the solid tumors and ascites was confirmed in both tumor models. A three consecutive-day treatment of IκBα-MnNPs in the ID8 model validated a shift towards M1 macrophage polarization in vivo. A clear therapeutic effect was observed with biweekly treatments over 2-3 weeks in the TBR5 model where significantly reduced tumor burden was accompanied by changes in immune cell composition, indicative of reduced immunosuppressive tumor microenvironment. No evidence of toxicity associated with MnNP treatment was observed in either model.

CONCLUSIONS

In mouse models of ovarian cancer, MnNPs were preferentially associated with macrophages in ascites fluid and solid tumors. Evidence of macrophage repolarization, increased inflammatory cues, and reduced tumor burden in IκBα-MnNP-treated mice indicate beneficial outcomes in models of established disease. We have provided evidence of a targeted, TAM-directed approach to increase anti-tumor immunity in ovarian cancer with strong translational potential for future clinical studies.

Panobinostat enhances olaparib efficacy by modifying expression of homologous recombination repair and immune transcripts in ovarian cancer

Histone deacetylase inhibitors (HDACi) sensitize homologous recombination (HR)-proficient human ovarian cancer cells to PARP inhibitors (PARPi). To investigate mechanisms of anti-tumor effects of combined HDACi/PARPi treatment we performed transcriptome analysis in HR- proficient human ovarian cancer cells and tested drug effects in established immunocompetent mouse ovarian cancer models. Human SKOV-3 cells were treated with vehicle (Con), olaparib (Ola), panobinostat (Pano) or Pano+Ola and RNA-seq analysis performed. DESeq2 identified differentially expressed HR repair and immune transcripts. Luciferised syngeneic mouse ovarian cancer cells (ID8-luc) were treated with the HDACi panobinostat alone or combined with olaparib and effects on cell viability, apoptosis, DNA damage and HR efficiency determined. C57BL/6 mice with intraperitoneally injected ID8-luc cells were treated with panobinostat and/or olaparib followed by assessment of tumor burden, markers of cell proliferation, apoptosis and DNA damage, tumor-infiltrating T cells and macrophages, and other immune cell populations in ascites fluid. There was a significant reduction in expression of 20/37 HR pathway genes by Pano+Ola, with immune and inflammatory-related pathways also significantly enriched by the combination. In ID8 cells, Pano+Ola decreased cell viability, HR repair, and enhanced DNA damage. Pano+Ola also co-operatively reduced tumor burden and proliferation, increased tumor apoptosis and DNA damage, enhanced infiltration of CD8+ T cells into tumors, and decreased expression of M2-like macrophage markers. In conclusion, panobinostat in combination with olaparib targets ovarian tumors through both direct cytotoxic and indirect immune-modulating effects.

Assessment of the immune landscapes of advanced ovarian cancer in an optimized in vivo model

BACKGROUND

Ovarian cancer (OC) is typically diagnosed late, associated with high rates of metastasis and the onset of ascites during late stage disease. Understanding the tumor microenvironment and how it impacts the efficacy of current treatments, including immunotherapies, needs effective in vivo models that are fully characterized. In particular, understanding the role of immune cells within the tumor and ascitic fluid could provide important insights into why OC fails to respond to immunotherapies. In this work, we comprehensively described the immune cell infiltrates in tumor nodules and the ascitic fluid within an optimized preclinical model of advanced ovarian cancer.

METHODS

Green Fluorescent Protein (GFP)-ID8 OC cells were injected intraperitoneally into C57BL/6 mice and the development of advanced stage OC monitored. Nine weeks after tumor injection, mice were sacrificed and tumor nodules analyzed to identify specific immune infiltrates by immunohistochemistry. Ascites, developed in tumor bearing mice over a 10-week period, was characterized by mass cytometry (CyTOF) to qualitatively and quantitatively assess the distribution of the immune cell subsets, and their relationship to ascites from ovarian cancer patients.

RESULTS

Tumor nodules in the peritoneal cavity proved to be enriched in T cells, antigen presenting cells and macrophages, demonstrating an active immune environment and cell-mediated immunity. Assessment of the immune landscape in the ascites showed the predominance of CD8+ , CD4+ , B- , and memory T cells, among others, and the coexistance of different immune cell types within the same tumor microenvironment.

CONCLUSIONS

We performed, for the first time, a multiparametric analysis of the ascitic fluid and specifically identify immune cell populations in the peritoneal cavity of mice with advanced OC. Data obtained highlights the impact of CytOF as a diagnostic tool for this malignancy, with the opportunity to concomitantly identify novel targets, and define personalized therapeutic options.

Nutritional Value and Preventive Role of Nigella sativa L. and Its Main Component Thymoquinone in Cancer: An Evidenced-Based Review of Preclinical and Clinical Studies

In recent times, scientific attention has been paid to different foods and their bioactive components for the ability to inhibit the onset and progress of different types of cancer. Nigella sativa extract, powder and seed oil and its main components, thymoquinone and α-hederin, have showed potent anticancer and chemosensitizing effects against various types of cancer, such as liver, colon, breast, renal, cervical, lung, ovarian, pancreatic, prostate and skin tumors, through the modulation of various molecular signaling pathways. Herein, the purpose of this review was to highlight the anticancer activity of Nigella sativa and it constitutes, focusing on different in vitro, in vivo and clinical studies and projects, in order to underline their antiproliferative, proapoptotic, cytotoxic and antimetastatic effects. Particular attention has been also given to the synergistic effect of Nigella sativa and it constitutes with chemotherapeutic drugs, and to the synthesized analogs of thymoquinone that seem to enhance the chemo-sensitizing potential. This review could be a useful step towards new research on N. sativa and cancer, to include this plant in the dietary treatments in support to conventional therapies, for the best achievement of therapeutic goals.

Current and Futuristic Roadmap of Ovarian Cancer Management: An Overview

Ovarian cancer (OC) is the most lethal gynecological malignancy among women worldwide. In most cases, it is diagnosed late at an advanced stage and does not respond well to existing therapies leading to its poor prognosis. In addition, other factors including epidemiological, complex histological diversity, multiple molecular alterations, and overlapping signaling pathways are also important contributors to poor disease outcome. Efforts have continued to develop a deeper understanding of the molecular pathogenesis and altered signaling nodes that provide hope for better clinical management through the development of novel approaches for early diagnosis, disease subtyping, prognosis, and therapy. In this chapter, we provide a detailed overview of OC and its histological subtypes and discuss prevalent molecular aberrations and active signaling pathways that drive OC progression. We also summarize various diagnostic and prognostic markers and therapeutic approaches currently being employed and discuss emerging findings that hold the potential to change the future course of OC management.

Increased canonical NF-kappaB signaling specifically in macrophages is sufficient to limit tumor progression in syngeneic murine models of ovarian cancer

BACKGROUND

New treatment options for ovarian cancer are urgently required. Tumor-associated macrophages (TAMs) are an attractive target for therapy; repolarizing TAMs from M2 (pro-tumor) to M1 (anti-tumor) phenotypes represents an important therapeutic goal. We have previously shown that upregulated NF-kappaB (NF-κB) signaling in macrophages promotes M1 polarization, but effects in the context of ovarian cancer are unknown. Therefore, we aimed to investigate the therapeutic potential of increasing macrophage NF-κB activity in immunocompetent mouse models of ovarian cancer.

METHODS

We have generated a transgenic mouse model, termed IKFM, which allows doxycycline-inducible overexpression of a constitutively active form of IKK2 (cIKK2) specifically within macrophages. The IKFM model was used to evaluate effects of increasing macrophage NF-κB activity in syngeneic murine TBR5 and ID8-Luc models of ovarian cancer in two temporal windows: 1) in established tumors, and 2) during tumor implantation and early tumor growth. Tumor weight, ascites volume, ascites supernatant and cells, and solid tumor were collected at sacrifice. Populations of macrophages and T cells within solid tumor and/or ascites were analyzed by immunofluorescent staining and qPCR, and soluble factors in ascitic fluid were analyzed by ELISA. Comparisons of control versus IKFM groups were performed by 2-tailed Mann-Whitney test, and a P-value < 0.05 was considered statistically significant.

RESULTS

Increased expression of the cIKK2 transgene in TAMs from IKFM mice was confirmed at the mRNA and protein levels. Tumors from IKFM mice, regardless of the timing of doxycycline (dox) administration, demonstrated greater necrosis and immune infiltration than control tumors. Analysis of IKFM ascites and tumors showed sustained shifts in macrophage populations away from the M2 and towards the anti-tumor M1 phenotype. There were also increased tumor-infiltrating CD3⁺/CD8⁺ T cells in IKFM mice, accompanied by higher levels of CXCL9, a T cell activating factor secreted by macrophages, in IKFM ascitic fluid.

CONCLUSIONS

In syngeneic ovarian cancer models, increased canonical NF-κB signaling in macrophages promoted anti-tumor TAM phenotypes and increased cytotoxic T cell infiltration, which was sufficient to limit tumor progression. This may present a novel translational approach for ovarian cancer treatment, with the potential to increase responses to T cell-directed therapy in future studies.

NF-κB Signaling in Ovarian Cancer

The NF-κB signaling pathway is a master and commander in ovarian cancer (OC) that promotes chemoresistance, cancer stem cell maintenance, metastasis and immune evasion. Many signaling pathways are dysregulated in OC and can activate NF-κB signaling through canonical or non-canonical pathways which have both overlapping and distinct roles in tumor progression. The activation of canonical NF-κB signaling has been well established for anti-apoptotic and immunomodulatory functions in response to the tumor microenvironment and the non-canonical pathway in cancer stem cell maintenance and tumor re-initiation. NF-κB activity in OC cells helps to create an immune-evasive environment and to attract infiltrating immune cells with tumor-promoting phenotypes, which in turn, drive constitutive NF-κB activation in OC cells to promote cell survival and metastasis. For these reasons, NF-κB is an attractive target in OC, but current strategies are limited and broad inhibition of this major signaling pathway in normal physiological and immunological functions may produce unwanted side effects. There are some promising pre-clinical outcomes from developing research to target and inhibit NF-κB only in the tumor-reinitiating cancer cell population of OC and concurrently activate canonical NF-κB signaling in immune cells to promote anti-tumor immunity.

Bipolar Tumor-Associated Macrophages in Ovarian Cancer as Targets for Therapy

Ovarian cancer, a rare but fatal disease, has been a challenging area in the field of gynecological cancer. Ovarian cancer is characterized by peritoneal metastasis, which is facilitated by a cross-talk between tumor cells and other cells in the tumor microenvironment (TME). In epithelial ovarian cancer, tumor-associated macrophages (TAMs) constitute over 50% of cells in the peritoneal TME and malignant ascites, and are potential targets for therapy. Here, we review the bipolar nature of TAMs and the evolving strategies to target TAMs in ovarian cancer.

Bipolar Tumor-Associated Macrophages in Ovarian Cancer as Targets for Therapy

Ovarian cancer, a rare but fatal disease, has been a challenging area in the field of gynecological cancer. Ovarian cancer is characterized by peritoneal metastasis, which is facilitated by a cross-talk between tumor cells and other cells in the tumor microenvironment (TME). In epithelial ovarian cancer, tumor-associated macrophages (TAMs) constitute over 50% of cells in the peritoneal TME and malignant ascites, and are potential targets for therapy. Here, we review the bipolar nature of TAMs and the evolving strategies to target TAMs in ovarian cancer.

Bipolar Tumor-Associated Macrophages in Ovarian Cancer as Targets for Therapy

Ovarian cancer, a rare but fatal disease, has been a challenging area in the field of gynecological cancer. Ovarian cancer is characterized by peritoneal metastasis, which is facilitated by a cross-talk between tumor cells and other cells in the tumor microenvironment (TME). In epithelial ovarian cancer, tumor-associated macrophages (TAMs) constitute over 50% of cells in the peritoneal TME and malignant ascites, and are potential targets for therapy. Here, we review the bipolar nature of TAMs and the evolving strategies to target TAMs in ovarian cancer.

Ovarian Cancer Immunotherapy: Preclinical Models and Emerging Therapeutics

Immunotherapy has emerged as one of the most promising approaches for ovarian cancer treatment. The tumor microenvironment (TME) is a key factor to consider when stimulating antitumoral responses as it consists largely of tumor promoting immunosuppressive cell types that attenuate antitumor immunity. As our understanding of the determinants of the TME composition grows, we have begun to appreciate the need to address both inter- and intra-tumor heterogeneity, mutation/neoantigen burden, immune landscape, and stromal cell contributions. The majority of immunotherapy studies in ovarian cancer have been performed using the well-characterized murine ID8 ovarian carcinoma model. Numerous other animal models of ovarian cancer exist, but have been underutilized because of their narrow initial characterizations in this context. Here, we describe animal models that may be untapped resources for the immunotherapy field because of their shared genomic alterations and histopathology with human ovarian cancer. We also shed light on the strengths and limitations of these models, and the knowledge gaps that need to be addressed to enhance the utility of preclinical models for testing novel immunotherapeutic approaches.

Aberrant over-expression of COX-1 intersects multiple pro-tumorigenic pathways in high-grade serous ovarian cancer

Cyclooxygenase-1 (COX-1) is implicated in ovarian cancer. However, patterns of COX expression and function have been unclear and controversial. In this report, patterns of COX-1 and COX-2 gene expression were obtained from RNA-seq data through The Cancer Genome Atlas. Our analysis revealed markedly higher COX-1 mRNA expression than COX-2 in high-grade serous ovarian cancers (HGSOC) and higher COX-1 expression in HGSOC tumors than 10 other tumor types. High expression of COX-1 in HGSOC tumors was confirmed in an independent tissue microarray. In contrast, lower or similar expression of COX-1 compared to COX-2 was observed in endometrioid, mucinous and clear cell tumors. Stable COX-1 knockdown in HGSOC-representative OVCAR-3 ovarian cancer cells reduced gene expression in multiple pro-tumorigenic pathways. Functional cell viability, clonogenicity, and migration/invasion assays were consistent with transcriptomic changes. These effects were reversed by stable over-expression of COX-1 in SKOV-3 cells. Our results demonstrate a distinct pattern of COX-1 over-expression in HGSOC tumors and strong association of COX-1 with multiple pro-tumorigenic pathways in ovarian cancer cells. These findings provide additional insight into the role of COX-1 in human ovarian cancer and support further development of methods to selectively target COX-1 in the management of HGSOC tumors.

Microenvironmental effects limit efficacy of thymoquinone treatment in a mouse model of ovarian cancer

Background

Ovarian cancer is the most lethal gynecologic malignancy, with limited treatment options for chemoresistant disease. An important link between inflammation and peritoneal spread of ovarian cancer is NF-κB signaling. Thymoquinone (TQ) exerts multiple anti-tumorigenic cellular effects, including NF-κB inhibition. We aimed to investigate the therapeutic potential of TQ in an established murine syngeneic model of ovarian cancer.

Methods

ID8-NGL mouse ovarian cancer cells stably expressing an NF-κB reporter transgene were injected intra-peritoneally into C57BL/6 mice, and mice were treated with TQ or vehicle for 10 or 30 days. TQ was combined with the macrophage depleting drug, liposomal clodronate, in selected experiments. Effects on peritoneal tumor burden were measured by volume of ascites, number of peritoneal implants and mesenteric tumor mass. NF-κB reporter activity and markers of proliferation and apoptosis were measured in tumors and in confirmatory in vitro experiments. Protein or mRNA expression of M1 (anti-tumor) and M2 (pro-tumor) macrophage markers, and soluble cytokine profiles, were examined from harvested ascites fluid, peritoneal lavages and/or tumor sections. 2-tailed Mann–Whitney tests were used for measuring differences between groups in in vivo experiments.

Results

Consistent with its effects in vitro, TQ reduced proliferation and increased apoptosis in ID8-NGL tumors after 10 and 30 day treatment. Prolonged TQ treatment did not significantly alter tumor number or mass compared to vehicle, but rather exerted an overall deleterious effect by stimulating ascites formation. Increased ascites was accompanied by elevated NF-κB activity in tumors and macrophages, increased pro-tumor M2 macrophages and expression of pro-tumorigenic soluble factors such as VEGF in ascites fluid, and increased tumor infiltration of M2 macrophages. In contrast, a 10 day exposure to TQ produced no ascites, and reduced tumor NF-κB activity, M2 macrophages and soluble VEGF levels. Peritoneal macrophage depletion by clodronate significantly reduced tumor burden. However, TQ-stimulated ascites was further enhanced by co-treatment with clodronate, with macrophages present overwhelmingly of the M2 phenotype.

Conclusions

Our findings show that pro-tumorigenic microenvironmental effects limited the efficacy of TQ in a syngeneic mouse model of ovarian cancer, and provide caution regarding its potential use in clinical trials in ovarian cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0463-5) contains supplementary material, which is available to authorized users.

Thymoquinone enhances cisplatin-response through direct tumor effects in a syngeneic mouse model of ovarian cancer

BACKGROUND

Ovarian cancer is the most lethal gynecologic malignancy characterized by the frequent development of resistance to platinum chemotherapy. Finding new drug combinations to overcome platinum resistance is a key clinical challenge. Thymoquinone (TQ) is a component of black seed oil that exerts multiple anti-tumorigenic effects on cells, including inhibition of NF-κB and promotion of DNA damage. We aimed to determine whether TQ enhances cisplatin cytotoxicity in cultured ovarian cancer cells and in an established murine syngeneic model of ovarian cancer.

METHODS

Ovarian cancer cell viability in vitro was measured by sulforhodamine B (SRB) assays, and drug interactions tested for synergism by isobologram analysis. ID8-NGL mouse ovarian cancer cells stably expressing an NF-κB reporter transgene were injected intra-peritoneally into C57BL/6 mice. After 30 day TQ and/or cisplatin treatment, we measured the following indices: tumor burden (ascites volume, number of peritoneal implants and mesenteric tumor mass); NF-κB reporter activity (luciferase assay); protein expression of the double-strand DNA break marker, pH2AX(ser139), the proliferation markers, Ki67/mib-1 and PCNA, and the apoptosis markers, cleaved caspase-3, cleaved PARP and Bax; and mRNA expression of NF-κB targets, TNF-α and IL-1β. Two-tailed Mann-Whitney tests were used for measuring differences between groups in mouse experiments.

RESULTS

In SRB assays, TQ and cisplatin synergized in ID8-NGL cells. In mice, cisplatin significantly reduced cell proliferation and increased apoptosis in tumors, resulting in decreased overall tumor burden. Combining TQ with cisplatin further decreased these indices, indicating co-operative effects between the drugs. TQ treatment promoted cisplatin-induced pH2AX expression in cultured cells and in tumors. While NF-κB inhibition by TQ induced anti-tumor effects in vitro, we made the unexpected observation that TQ alone increased both tumor NF-κB activity and formation of ascites in vivo.

CONCLUSIONS

TQ enhanced cisplatin-mediated cytoxicity in ovarian cancer cells in vitro and in a mouse syngeneic model, effects associated with increased DNA damage. However, our results strongly caution that TQ treatment alone may have an overall deleterious effect in the immunocompetent host through stimulation of ascites. Since TQ is a potential candidate for future clinical trials in ovarian cancer patients, this finding has considerable potential relevance to the clinic.

The homeoprotein DLX4 stimulates NF-κB activation and CD44-mediated tumor-mesothelial cell interactions in ovarian cancer

Ovarian cancers often highly express inflammatory cytokines and form implants throughout the peritoneal cavity. However, the mechanisms that drive inflammatory signaling and peritoneal metastasis of ovarian cancer are poorly understood. We previously identified that high expression of DLX4, a transcription factor encoded by a homeobox gene, is associated with reduced survival of ovarian cancer patients. In this study, we identified that DLX4 stimulates attachment of ovarian tumor cells to peritoneal mesothelial cells in vitro and increases the numbers of peritoneal implants in xenograft models. DLX4 induced expression of the cell surface molecule CD44 in ovarian tumor cells, and inhibition of CD44 abrogated the ability of DLX4 to stimulate tumor-mesothelial cell interactions. The induction of CD44 by DLX4 was attributed to increased activity of NF-κB that was stimulated by the inflammatory cytokine IL-1β, a transcriptional target of DLX4. The stimulatory effects of DLX4 on CD44 levels and tumor-mesothelial cell interactions were abrogated when IL-1β or NF-κB was inhibited in tumor cells. Furthermore, DLX4 expression levels strongly correlated with NF-κB activation and disease stage in clinical specimens of ovarian cancer. Collectively, these findings indicate that DLX4 induces CD44 by stimulating IL-1β-mediated NF-κB activity, thereby promoting peritoneal metastasis of ovarian cancer.

Biocompatible mannosylated endosomal-escape nanoparticles enhance selective delivery of short nucleotide sequences to tumor associated macrophages

Tumor associated macrophages (TAMs) can modify the tumor microenvironment to create a pro-tumor niche. Manipulation of the TAM phenotype is a novel, potential therapeutic approach to engage anti-cancer immunity. siRNA is a molecular tool for knockdown of specific mRNAs that is tunable in both strength and duration. The use of siRNA to reprogram TAMs to adopt an immunogenic, anti-tumor phenotype is an attractive alternative to ablation of this cell population. One current difficulty with this approach is that TAMs are difficult to specifically target and transfect. We report here successful utilization of novel mannosylated polymer nanoparticles (MnNP) that are capable of escaping the endosomal compartment to deliver siRNA to TAMs in vitro and in vivo. Transfection with MnNP-siRNA complexes did not significantly decrease TAM cell membrane integrity in culture, nor did it create adverse kidney or liver function in mice, even at repeated doses of 5 mg kg(-1). Furthermore, MnNP effectively delivers labeled nucleotides to TAMs in mice with primary mammary tumors. We also confirmed TAM targeting in the solid tumors disseminated throughout the peritoneum of ovarian tumor bearing mice following injection of fluorescently labeled MnNP-nucleotide complexes into the peritoneum. Finally, we show enhanced uptake of MnNP in lung metastasis associated macrophages compared to untargeted particles when using an intubation delivery method. In summary, we have shown that MnNP specifically and effectively deliver siRNA to TAMs in vivo.

Estrogen signaling crosstalk: Implications for endocrine resistance in ovarian cancer

Resistance to anti-estrogen therapies is a prominent challenge in the treatment of ovarian cancer. Tumors develop endocrine resistance by acquiring adaptations that help them rely on alternative oncogenic signaling cascades, which crosstalk with estrogen signaling pathways. An understanding of estrogen signaling crosstalk with these growth promoting cascades is essential in order to maximize efficacy of anti-estrogen treatments in ovarian cancer. Herein, we provide an overview of estrogen signaling in ovarian cancer and discuss the major challenges associated with anti-estrogen therapies. We also review what is currently known about how genomic and non-genomic estrogen signaling pathways crosstalk with several major oncogenic signaling cascades. The insights provided here illustrate existing strategies for targeting endocrine resistant ovarian tumors and may help identify new strategies to improve the treatment of this disease.

Recent technological advances in using mouse models to study ovarian cancer

Serous epithelial ovarian cancer (SEOC) is the most lethal gynecological cancer in the United States with disease recurrence being the major cause of morbidity and mortality. Despite recent advances in our understanding of the molecular mechanisms responsible for the development of SEOC, the survival rate for women with this disease has remained relatively unchanged in the last two decades. Preclinical mouse models of ovarian cancer, including xenograft, syngeneic, and genetically engineered mice, have been developed to provide a mechanism for studying the development and progression of SEOC. Such models strive to increase our understanding of the etiology and dissemination of ovarian cancer in order to overcome barriers to early detection and resistance to standard chemotherapy. Although there is not a single model that is most suitable for studying ovarian cancer, improvements have led to current models that more closely mimic human disease in their genotype and phenotype. Other advances in the field, such as live animal imaging techniques, allow effective monitoring of the microenvironment and therapeutic efficacy. New and improved preclinical mouse models, combined with technological advances to study such models, will undoubtedly render success of future human clinical trials for patients with SEOC.

A high M1/M2 ratio of tumor-associated macrophages is associated with extended survival in ovarian cancer patients

BACKGROUND

Tumor-associated macrophages (TAMs) are classified into two major phenotypes, M1 and M2. M1 TAMs suppress cancer progression, while M2 TAMs promote it. However, little is known regarding the role of TAMs in the development of ovarian cancer. Here, we investigated the relationship between TAM distribution patterns (density, microlocalization, and differentiation) and ovarian cancer histotypes, and we explored whether altered TAM distribution patterns influence long-term outcomes in ovarian cancer patients.

METHODS

A total of 112 ovarian cancer patients were enrolled in this study, and the subjects were divided into two groups according to their survival (< 5 years vs. ≥ 5 years). Immunohistochemistry and immunofluorescence were used to determine the density, microlocalization, and differentiation status of TAMs in ovarian cancer tissues for each histotype. Kaplan-Meier survival and multivariate Cox regression analyses were used to evaluate the prognostic significance of TAM-related parameters in ovarian cancer.

RESULTS

TAMs most frequently infiltrated into the cancer tissue of the serous histotype, followed by mucinous, undifferentiated, endometrioid, and clear cell histotypes (p = 0.049). The islet/stroma ratio of total TAMs varied among the cancer histotypes, with mucinous and undifferentiated cancers displaying the lowest and highest ratios, respectively (p = 0.005). The intratumoral TAM density significantly increased with increasing cancer stage and grade (p = 0.023 and 0.006, respectively). However, the overall M1/M2 TAM ratio decreased as the cancer stage increased (p = 0.012). In addition, the intra-islet M1/M2 ratio inversely correlated with the residual site size (p = 0.004). Among the TAM-related parameters, only the increased overall and intra-islet M1/M2 TAM ratios displayed prognostic significance in both the Kaplan-Meier survival and multivariate Cox regression analyses; however, the values of these two parameters did not differ significantly among the cancer histotypes.

CONCLUSIONS

The patients with increased overall or intra-islet M1/M2 TAM ratios presented with an improved 5-year prognosis. Nevertheless, the TAM distribution patterns did not influence the overall outcomes of different ovarian cancer histotypes.