NOS2 and COX2 Provide Key Spatial Targets that Determine Outcome in ER- Breast Cancer

Estrogen receptor-negative (ER-) breast cancer is an aggressive breast cancer subtype with limited therapeutic options. Upregulated expression of both inducible nitric oxide synthase (NOS2) and cyclo-oxygenase (COX2) in breast tumors predicts poor clinical outcomes. Signaling molecules released by these enzymes activate oncogenic pathways, driving cancer stemness, metastasis, and immune suppression. The influence of tumor NOS2/COX2 expression on the landscape of immune markers using multiplex fluorescence imaging of 21 ER- breast tumors were stratified for survival. A powerful relationship between tumor NOS2/COX2 expression and distinct CD8+ T cell phenotypes was observed at 5 years post-diagnosis. These results were confirmed in a validation cohort using gene expression data showing that ratios of NOS2 to CD8 and COX2 to CD8 are strongly associated with poor outcomes in high NOS2/COX2-expressing tumors. Importantly, multiplex imaging identified distinct CD8+ T cell phenotypes relative to tumor NOS2/COX2 expression in Deceased vs Alive patient tumors at 5-year survival. CD8+NOS2-COX2- phenotypes defined fully inflamed tumors with significantly elevated CD8+ T cell infiltration in Alive tumors expressing low NOS2/COX2. In contrast, two distinct phenotypes including inflamed CD8+NOS2+COX2+ regions with stroma-restricted CD8+ T cells and CD8-NOS2-COX2+ immune desert regions with abated CD8+ T cell penetration, were significantly elevated in Deceased tumors with high NOS2/COX2 expression. These results were supported by applying an unsupervised nonlinear dimensionality-reduction technique, UMAP, correlating specific spatial CD8/NOS2/COX2 expression patterns with patient survival. Moreover, spatial analysis of the CD44v6 and EpCAM cancer stem cell (CSC) markers within the CD8/NOS2/COX2 expression landscape revealed positive correlations between EpCAM and inflamed stroma-restricted CD8+NOS2+COX2+ phenotypes at the tumor/stroma interface in deceased patients. Also, positive correlations between CD44v6 and COX2 were identified in immune desert regions in deceased patients. Furthermore, migrating tumor cells were shown to occur only in the CD8-NOS2+COX2+ regions, identifying a metastatic hot spot. Taken together, this study shows the strength of spatial localization analyses of the CD8/NOS2/COX2 landscape, how it shapes the tumor immune microenvironment and the selection of aggressive tumor phenotypes in distinct regions that lead to poor clinical outcomes. This technique could be beneficial for describing tumor niches with increased aggressiveness that may respond to clinically available NOS2/COX2 inhibitors or immune-modulatory agents.

Spatial analysis of NOS2 and COX2 interaction with T-effector cells reveals immunosuppressive landscapes associated with poor outcome in ER- breast cancer patients

Multiple immunosuppressive mechanisms exist in the tumor microenvironment that drive poor outcomes and decrease treatment efficacy. The co-expression of NOS2 and COX2 is a strong predictor of poor prognosis in ER- breast cancer and other malignancies. Together, they generate pro-oncogenic signals that drive metastasis, drug resistance, cancer stemness, and immune suppression. Using an ER- breast cancer patient cohort, we found that the spatial expression patterns of NOS2 and COX2 with CD3+CD8+PD1- T effector (Teff) cells formed a tumor immune landscape that correlated with poor outcome. NOS2 was primarily associated with the tumor-immune interface, whereas COX2 was associated with immune desert regions of the tumor lacking Teff cells. A higher ratio of NOS2 or COX2 to Teff was highly correlated with poor outcomes. Spatial analysis revealed that regional clustering of NOS2 and COX2 was associated with stromal-restricted Teff, while only COX2 was predominant in immune deserts. Examination of other immunosuppressive elements, such as PDL1/PD1, Treg, B7H4, and IDO1, revealed that PDL1/PD1, Treg, and IDO1 were primarily associated with restricted Teff, whereas B7H4 and COX2 were found in tumor immune deserts. Regardless of the survival outcome, other leukocytes, such as CD4 T cells and macrophages, were primarily in stromal lymphoid aggregates. Finally, in a 4T1 model, COX2 inhibition led to a massive cell infiltration, thus validating the hypothesis that COX2 is an essential component of the Teff exclusion process and, thus, tumor evasion. Our study indicates that NOS2/COX2 expression plays a central role in tumor immunosuppression. Our findings indicate that new strategies combining clinically available NOS2/COX2 inhibitors with various forms of immune therapy may open a new avenue for the treatment of aggressive ER-breast cancers.

Pyruvate dehydrogenase operates as an intramolecular nitroxyl generator during macrophage metabolic reprogramming

M1 macrophages enter a glycolytic state when endogenous nitric oxide (NO) reprograms mitochondrial metabolism by limiting aconitase 2 and pyruvate dehydrogenase (PDH) activity. Here, we provide evidence that NO targets the PDH complex by using lipoate to generate nitroxyl (HNO). PDH E2-associated lipoate is modified in NO-rich macrophages while the PDH E3 enzyme, also known as dihydrolipoamide dehydrogenase (DLD), is irreversibly inhibited. Mechanistically, we show that lipoate facilitates NO-mediated production of HNO, which interacts with thiols forming irreversible modifications including sulfinamide. In addition, we reveal a macrophage signature of proteins with reduction-resistant modifications, including in DLD, and identify potential HNO targets. Consistently, DLD enzyme is modified in an HNO-dependent manner at Cys477 and Cys484, and molecular modeling and mutagenesis show these modifications impair the formation of DLD homodimers. In conclusion, our work demonstrates that HNO is produced physiologically. Moreover, the production of HNO is dependent on the lipoate-rich PDH complex facilitating irreversible modifications that are critical to NO-dependent metabolic rewiring.

Targeting Nitric Oxide: Say NO to Metastasis

Utilizing targeted therapies capable of reducing cancer metastasis, targeting chemoresistant and self-renewing cancer stem cells, and augmenting the efficacy of systemic chemo/radiotherapies is vital to minimize cancer-associated mortality. Targeting nitric oxide synthase (NOS), a protein within the tumor microenvironment, has gained interest as a promising therapeutic strategy to reduce metastatic capacity and augment the efficacy of chemo/radiotherapies in various solid malignancies. Our review highlights the influence of nitric oxide (NO) in tumor progression and cancer metastasis, as well as promising preclinical studies that evaluated NOS inhibitors as anticancer therapies. Lastly, we highlight the prospects and outstanding challenges of using NOS inhibitors in the clinical setting.

Interferon-gamma is quintessential for NOS2 and COX2 expression in ER- breast tumors that lead to poor outcome

A strong correlation between NOS2 and COX2 tumor expression and poor clinical outcomes in ER breast cancer has been established. However, the mechanisms of tumor induction of these enzymes are unclear. Analysis of The Cancer Genome Atlas (TCGA) revealed correlations between NOS2 and COX2 expression and Th1 cytokines. Herein, single-cell RNAseq analysis of TNBC cells shows potent NOS2 and COX2 induction by IFNγ combined with IL1β or TNFα. Given that IFNγ is secreted by cytolytic lymphocytes, which improve clinical outcomes, this role of IFNγ presents a dichotomy. To explore this conundrum, tumor NOS2, COX2, and CD8⁺ T cells were spatially analyzed in aggressive ER-, TNBC, and HER2 + breast tumors. High expression and clustering of NOS2-expressing tumor cells occurred at the tumor/stroma interface in the presence of stroma-restricted CD8⁺ T cells. High expression and clustering of COX2-expressing tumor cells extended into immune desert regions in the tumor core where CD8⁺ T cell penetration was limited or absent. Moreover, high NOS2-expressing tumor cells were proximal to areas with increased satellitosis, suggestive of cell clusters with a higher metastatic potential. Further in vitro experiments revealed that IFNγ + IL1β/TNFα increased the elongation and migration of treated tumor cells. This spatial analysis of the tumor microenvironment provides important insight into distinct neighborhoods where stroma-restricted CD8⁺ T cells exist proximal to NOS2-expressing tumor niches that could have increased metastatic potential.

Interferon-gamma is Quintessential for NOS2 and COX2 Expression in ER - Breast Tumors that Lead to Poor Outcome

A strong correlation between NOS2 and COX2 tumor expression and poor clinical outcomes in ER-breast cancer has been established. However, mechanisms of tumor induction of these enzymes are unclear. Analysis of The Cancer Genome Atlas (TCGA) revealed correlations between NOS2 and COX2 expression and Th1 cytokines. Herein, single cell RNAseq analysis of TNBC cells shows potent NOS2 and COX2 induction by IFNγ combined with IL1β or TNFα. Given that IFNγ is secreted by cytolytic lymphocytes, which improve clinical outcomes, this role of IFNγpresents a dichotomy. To explore this conundrum, tumor NOS2, COX2, and CD8 ⁺ T cells were spatially analyzed in aggressive ER-, TNBC, and HER2+ breast tumors. High expression and clustering of NOS2-expressing tumor cells occurred at the tumor/stroma interface in the presence of stroma-restricted CD8 ⁺ T cells. High expression and clustering of COX2-expressing tumor cells extended into immune desert regions in the tumor core where CD8 ⁺ T cell penetration was limited or absent. Moreover, high NOS2-expressing tumor cells were proximal to areas with increased satellitosis suggestive of cell clusters with a higher metastatic potential. Further in vitro experiments revealed that IFNγ+IL1β/TNFα increased elongation and migration of treated tumor cells. This spatial analysis of the tumor microenvironment provides important insight of distinct neighborhoods where stroma-restricted CD8 ⁺ T cells exist proximal to NOS2-expressing tumor niches that could have increased metastatic potential.

Abstract 2539: Tumor necrosis factor related apoptosis inducing ligand (TRAIL) induces cytokine release via the alternative NFKB2 pathway in triple negative breast cancer cells (TNBC) and modulates neutrophil chemotaxis

TRAIL induces apoptosis in many preclinical cancer models including breast cancers and has been extensively studied as a potential cancer therapeutic. However, its efficacy in clinical trials is limited, suggesting that there are unknown modulatory mechanisms responsible for its lack of TRAIL activity in vivo. We hypothesized that TRAIL treatment elicits transcriptional changes in TNBC cells that alter the immune milieu, modulating the therapeutic efficacy. To investigate the hypothesis, we performed RNAseq analysis of MDA-MB231 cells treated with TRAIL for different time points, followed by validation with RT-PCR in various TNBC cells. TRAIL treatment of the TNBC significantly induced expression of a number of cytokines, such as CXCL1, CXCL2, CXCL3, CXCL8, CXCL11, IL6, which are known to affect neutrophil function. Mechanistically, induction of these cytokines was predominantly mediated by Death Receptor 5 and Caspase-8 protein, but not Caspase-8 enzymatic activity. Gene Set Enrichment Analysis of the RNAseq indicated that NFKB pathway-mediated TNF-alpha signaling was significantly enriched. Concordantly, we confirmed that both canonical NFKB1 and non-canonical NFKB2 pathways were activated by TRAIL. However, siRNA knockdown experiments indicated that the induction of the cytokine mRNAs was primarily dependent on the NFKB2 pathway. Neutrophils isolated from healthy human donors incubated with supernatants from TNBC cells in vitro indicated that TRAIL-induced CXCLs’ (1, 2, 3, 8) and IL6 significantly increased neutrophil chemotaxis in a NFKB2-dependent manner. Moreover, neutrophils pre-incubated with supernatants from TRAIL-treated TNBC significantly inhibited its cytotoxic effect in TNBCs in a NFKB2-dependent pathway. Further RNAseq and RT-PCR of neutrophils incubated with by either TRAIL or supernatant of MDA-MB231 cells treated with TRAIL revealed significant enrichment of inflammatory pathway-related genes as well as increased expression of immune modulating cytokines. These results suggested that TRAIL exerts a pro-inflammatory role towards immune cells in tumor microenvironment. CODEX (CO-Detection by indEXing) analysis of in vivo TNBC xenografts from mice treated with the TRAIL agonist MEDI3039 confirmed that TRAIL treatment increases the number of neutrophils in the tumor. Using TNBC organoids and humanized mice models, the changes in tumor immune environment caused by TRAIL are currently under investigation. Collectively, our study suggests the novel role of TRAIL-induced NFKB2-dependent cytokine production that affects neutrophil functions, leading to modulation of the immune response in TNBC.

Citation Format: Manjari Kundu, Yoshimi Endo Greer, Lisa A. Ridnour, David A. Wink, Stan Lipkowitz. Tumor necrosis factor related apoptosis inducing ligand (TRAIL) induces cytokine release via the alternative NFKB2 pathway in triple negative breast cancer cells (TNBC) and modulates neutrophil chemotaxis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2539.

Chronic Exposure to Nitric Oxide Induces P53 Mutations and Malignant-like Features in Human Breast Epithelial Cells

The small endogenous signaling molecule nitric oxide (NO) has been linked with chronic inflammation and cancer. The effects of NO are both concentration and temporally dependent; under some conditions, NO protects against damage caused by reactive oxygen species and activates P53 signaling. During chronic inflammation, NO causes DNA damage and inhibits repair proteins. To extend our understanding of the roles of NO during carcinogenesis, we investigated the possible effects of chronic NO exposure on MCF10A breast epithelial cells, as defined by changes in cellular morphology, chromosome/genomic stability, RNA, and protein expression, and altered cell phenotypes. Human MCF10A cells were maintained in varying doses of the NO donor DETANO for three weeks. Distinct patterns of genomic modifications in TP53 and KRAS target genes were detected in NO-treated cells when compared to background mutations. In addition, quantitative real-time PCR demonstrated an increase in the expression of cancer stem cell (CSC) marker CD44 after prolonged exposure to 300 μM DETANO. While similar changes in cell morphology were found in cells exposed to 300-500 μM DETANO, cells cultured in 100 μM DETANO exhibited enhanced motility. In addition, 100 μM NO-treated cells proliferated in serum-free media and selected clonal populations and pooled cells formed colonies in soft agar that were clustered and disorganized. These findings show that chronic exposure to NO generates altered breast epithelial cell phenotypes with malignant characteristics.

IL-27 induces an IFN-like signature in murine macrophages which in turn modulate colonic epithelium

Mucosal delivery of IL-27 has been shown to have a therapeutic benefit in murine models of inflammatory bowel disease (IBD). The IL-27 effect was associated with phosphorylated STAT1 (pSTAT1), a product of IL27 receptor signaling, in bowel tissue. To determine whether IL-27 acted directly on colonic epithelium, murine colonoids and primary intact colonic crypts were shown to be unresponsive to IL-27 in vitro and to lack detectable IL-27 receptors. On the other hand, macrophages, which are present in inflamed colon tissue, were responsive to IL-27 in vitro. IL-27 induced pSTAT1 in macrophages, the transcriptome indicated an IFN-like signature, and supernatants induced pSTAT1 in colonoids. IL-27 induced anti-viral activity in macrophages and MHC Class II induction. We conclude that the effects of mucosal delivery of IL-27 in murine IBD are in part based on the known effects of IL27 inducing immunosuppression of T cells mediated by IL-10. We also conclude that IL-27 has potent effects on macrophages in inflamed colon tissue, generating mediators that in turn act on colonic epithelium.

New nitrosyl ruthenium complexes with combined activities for multiple cardiovascular disorders

Nitrosyl ruthenium complexes are promising platforms for nitric oxide (NO) and nitroxyl (HNO) release, which exert their therapeutic application. In this context, we developed two polypyridinic compounds with general formula...

The Chemical Biology of NO that Regulates Oncogenic Signaling and Metabolism: NOS2 and Its Role in Inflammatory Disease

Nitric oxide (NO) and the enzyme that synthesizes it, nitric oxide synthase 2 (NOS2), have emerged as key players in inflammation and cancer. Expression of NOS2 in tumors has been correlated both with positive outcomes and with poor prognoses. The chemistry of NO is the major determinate to the biological outcome and the concentration of NO, which can range over five orders of magnitude, is critical in determining which pathways are activated. It is the activation of specific oncogenic and immunological mechanisms that shape the outcome. The kinetics of specific reactions determine the mechanisms of action. In this review, the relevant reactions of NO and related species are discussed with respect to these oncogenic and immunological signals.

Systemic Nos2 Depletion and Cox inhibition limits TNBC disease progression and alters lymphoid cell spatial orientation and density

Antitumor immune polarization is a key predictor of clinical outcomes to cancer therapy. An emerging concept influencing clinical outcome involves the spatial location of CD8+ T cells, within the tumor. Our earlier work demonstrated immunosuppressive effects of NOS2 and COX2 tumor expression. Here, we show that NOS2/COX2 levels influence both the polarization and spatial location of lymphoid cells including CD8+ T cells. Importantly, elevated tumor NOS2/COX2 correlated with exclusion of CD8+ T cells from the tumor epithelium. In contrast, tumors expressing low NOS2/COX2 had increased CD8+ T cell penetration into the tumor epithelium. Consistent with a causative relationship between these observations, pharmacological inhibition of COX2 with indomethacin dramatically reduced tumor growth of the 4T1 model of TNBC in both WT and Nos2- mice. This regimen led to complete tumor regression in ∼20-25% of tumor-bearing Nos2- mice, and these animals were resistant to tumor rechallenge. Th1 cytokines were elevated in the blood of treated mice and intratumoral CD4+ and CD8+ T cells were higher in mice that received indomethacin when compared to control untreated mice. Multiplex immunofluorescence imaging confirmed our phenotyping results and demonstrated that targeted Nos2/Cox2 blockade improved CD8+ T cell penetration into the 4T1 tumor core. These findings are consistent with our observations in low NOS2/COX2 expressing breast tumors proving that COX2 activity is responsible for limiting the spatial distribution of effector T cells in TNBC. Together these results suggest that clinically available NSAID's may provide a cost-effective, novel immunotherapeutic approach for treatment of aggressive tumors including triple negative breast cancer.

Nitric Oxide and Cancer: When to Give and When to Take Away?

The mechanistic roles of nitric oxide (NO) during cancer progression have been important considerations since its discovery as an endogenously generated free radical. Nonetheless, the impacts of this signaling molecule can be seemingly contradictory, being both pro-and antitumorigenic, which complicates the development of cancer treatments based on the modulation of NO fluxes in tumors. At a fundamental level, low levels of NO drive oncogenic pathways, immunosuppression, metastasis, and angiogenesis, while higher levels lead to apoptosis and reduced hypoxia and also sensitize tumors to conventional therapies. However, clinical outcome depends on the type and stage of the tumor as well as the tumor microenvironment. In this Viewpoint, the current understanding of the concentration, spatial, and temporal dependence of responses to NO is correlated with potential treatment and prevention technologies and strategies.

Tumour irradiation combined with vascular-targeted photodynamic therapy enhances antitumour effects in pre-clinical prostate cancer

BACKGROUND

There is a need to improve the treatment of prostate cancer (PCa) and reduce treatment side effects. Vascular-targeted photodynamic therapy (VTP) is a focal therapy for low-risk low-volume localised PCa, which rapidly disrupts targeted tumour vessels. There is interest in expanding the use of VTP to higher-risk disease. Tumour vasculature is characterised by vessel immaturity, increased permeability, aberrant branching and inefficient flow. FRT alters the tumour microenvironment and promotes transient 'vascular normalisation'. We hypothesised that multimodality therapy combining fractionated radiotherapy (FRT) and VTP could improve PCa tumour control compared against monotherapy with FRT or VTP.

METHODS

We investigated whether sequential delivery of FRT followed by VTP 7 days later improves flank TRAMP-C1 PCa tumour allograft control compared to monotherapy with FRT or VTP.

RESULTS

FRT induced 'vascular normalisation' changes in PCa flank tumour allografts, improving vascular function as demonstrated using dynamic contrast-enhanced magnetic resonance imaging. FRT followed by VTP significantly delayed tumour growth in flank PCa allograft pre-clinical models, compared with monotherapy with FRT or VTP, and improved overall survival.

CONCLUSION

Combining FRT and VTP may be a promising multimodal approach in PCa therapy. This provides proof-of-concept for this multimodality treatment to inform early phase clinical trials.

An in vitro tumorigenesis model based on live-cell-generated oxygen and nutrient gradients

The tumor microenvironment (TME) is multi-cellular, spatially heterogenous, and contains cell-generated gradients of soluble molecules. Current cell-based model systems lack this complexity or are difficult to interrogate microscopically. We present a 2D live-cell chamber that approximates the TME and demonstrate that breast cancer cells and macrophages generate hypoxic and nutrient gradients, self-organize, and have spatially varying phenotypes along the gradients, leading to new insights into tumorigenesis.

Gilmore et al. describe an in vitro tumorigenesis model that produces cell-generated gradients of oxygen and nutrients. Its 2D configuration simplifies live cell, immunofluorescent, and microscopic interrogation of cancer cell behaviour in differentially developed tumour microenvironment conditions, including co-culture systems.

Comment on "Evidence that the ProPerDP method is inadequate for protein persulfidation detection due to lack of specificity"

The recent report by Fan et al alleged that the ProPerDP method is inadequate for the detection of protein persulfidation. Upon careful evaluation of their work, we conclude that the claim made by Fan et al is not supported by their data, rather founded in methodological shortcomings. It is understood that the ProPerDP method generates a mixture of cysteine-containing and non-cysteine-containing peptides. Instead, Fan et al suggested that the detection of non-cysteine-containing peptides indicates nonspecific alkylation at noncysteine residues. However, if true, then such peptides would not be released by reduction and therefore not appear as products in the reported workflow. Moreover, the authors' biological assessment of ProPerDP using Escherichia coli mutants was based on assumptions that have not been confirmed by other methods. We conclude that Fan et al did not rigorously assess the method and that ProPerDP remains a reliable approach for analyses of protein per/polysulfidation.

Nitric Oxide in Macrophage Immunometabolism: Hiding in Plain Sight

Nitric Oxide (NO) is a soluble endogenous gas with various biological functions like signaling, and working as an effector molecule or metabolic regulator. In response to inflammatory signals, immune myeloid cells, like macrophages, increase production of cytokines and NO, which is important for pathogen killing. Under these proinflammatory circumstances, called “M1”, macrophages undergo a series of metabolic changes including rewiring of their tricarboxylic acid (TCA) cycle. Here, we review findings indicating that NO, through its interaction with heme and non-heme metal containing proteins, together with components of the electron transport chain, functions not only as a regulator of cell respiration, but also a modulator of intracellular cell metabolism. Moreover, diverse effects of NO and NO-derived reactive nitrogen species (RNS) involve precise interactions with different targets depending on concentration, temporal, and spatial restrictions. Although the role of NO in macrophage reprogramming has been in evidence for some time, current models have largely minimized its importance. It has, therefore, been hiding in plain sight. A review of the chemical properties of NO, past biochemical studies, and recent publications, necessitates that mechanisms of macrophage TCA reprogramming during stimulation must be re-imagined and re-interpreted as mechanistic results of NO exposure. The revised model of metabolic rewiring we describe here incorporates many early findings regarding NO biochemistry and brings NO out of hiding and to the forefront of macrophages immunometabolism.

Metabolic characterization of aggressive breast cancer cells exhibiting invasive phenotype: impact of non-cytotoxic doses of 2-DG on diminishing invasiveness

Background

Metabolic reprogramming is being recognized as a fundamental hallmark of cancer, and efforts to identify drugs that can target cancer metabolism are underway. In this study, we used human breast cancer (BC) cell lines and established their invading phenotype (INV) collected from transwell inserts to compare metabolome differences and evaluate prognostic significance of the metabolome in aggressive BC invasiveness.

Methods

The invasiveness of seven human BC cell lines were compared using the transwell invasion assay. Among these, INV was collected from SUM149, which exhibited the highest invasiveness. Levels of metabolites in INV were compared with those of whole cultured SUM149 cells (WCC) using CE-TOFMS. The impact of glycolysis in INV was determined by glucose uptake assay using fluorescent derivative of glucose (2-NBDG), and significance of glycolysis, or tricarboxylic acid cycle (TCA) and electron transport chain (ETC) in the invasive process were further determined in aggressive BC cell lines, SUM149, MDA-MB-231, HCC1937, using invasion assays in the presence or absence of inhibitors of glycolysis, TCA cycle or ETC.

Results

SUM149 INV sub-population exhibited a persistent hyperinvasive phenotype. INV were hyper-glycolytic with increased glucose (2-NBDG) uptake; diminished glucose-6-phosphate (G6P) levels but elevated pyruvate and lactate, along with higher expression of phosphorylated-pyruvate dehydrogenase (pPDH) compared to WCC. Notably, inhibiting of glycolysis with lower doses of 2-DG (1 mM), non-cytotoxic to MDA-MB-231 and HCC1937, was effective in diminishing invasiveness of aggressive BC cell lines. In contrast, 3-Nitropropionic acid (3-NA), an inhibitor of succinate dehydrogenase, the enzyme that oxidizes succinate to fumarate in TCA cycle, and functions as complex II of ETC, had no significant effect on their invasiveness, although levels of TCA metabolites or detection of mitochondrial membrane potential with JC-1 staining, indicated that INV cells originally had functional TCA cycles and membrane potential.

Conclusions

Hyper-glycolytic phenotype of invading cells caters to rapid energy production required for invasion while TCA cycle/ETC cater to cellular energy needs for sustenance in aggressive BC. Lower, non-cytotoxic doses of 2-DG can hamper invasion and can potentially be used as an adjuvant with other anti-cancer therapies without the usual side-effects associated with cytotoxic doses.

Impacts of combining anti-PD-L1 immunotherapy and radiotherapy on the tumour immune microenvironment in a murine prostate cancer model

BACKGROUND

Radiotherapy enhances innate and adaptive anti-tumour immunity. It is unclear whether this effect may be harnessed by combining immunotherapy with radiotherapy fractions used to treat prostate cancer. We investigated tumour immune microenvironment responses of pre-clinical prostate cancer models to radiotherapy. Having defined this landscape, we tested whether radiotherapy-induced tumour growth delay could be enhanced with anti-PD-L1.

METHODS

Hypofractionated radiotherapy was delivered to TRAMP-C1 and MyC-CaP flank allografts. Tumour growth delay, tumour immune microenvironment flow-cytometry, and immune gene expression were analysed. TRAMP-C1 allografts were then treated with 3 × 5 Gy ± anti-PD-L1.

RESULTS

3 × 5 Gy caused tumour growth delay in TRAMP-C1 and MyC-CaP. Tumour immune microenvironment changes in TRAMP-C1 at 7 days post-radiotherapy included increased tumour-associated macrophages and dendritic cells and upregulation of PD-1/PD-L1, CD8+ T-cell, dendritic cell, and regulatory T-cell genes. At tumour regrowth post-3 × 5 Gy the tumour immune microenvironment flow-cytometry was similar to control tumours, however CD8+, natural killer and dendritic cell gene transcripts were reduced. PD-L1 inhibition plus 3 × 5 Gy in TRAMP-C1 did not enhance tumour growth delay versus monotherapy.

CONCLUSION

3 × 5 Gy hypofractionated radiotherapy can result in tumour growth delay and immune cell changes in allograft prostate cancer models. Adjuncts beyond immunomodulation may be necessary to improve the radiotherapy-induced anti-tumour response.

Abstract 6071: Role of nitric oxide in the invasive pancreatic cancer cells

Pancreatic cancer is a metastatic tumor with an extremely low 5-year survival rate. Metastasis is a main cause of patient mortality as it is extremely difficult to treat. Thus, understanding the characteristics of cancer cell populations exhibiting the invasive phenotype is fundamental for developing novel strategies to counter metastasis and improve therapeutic efficacy. To characterize these invasive phenotypes, we compared the human PANC-1 parent cell line with PANC-1 cells (INV) that invaded through transwell inserts. INV cells exhibited increased invasiveness and higher resistance to Carbon-ion radiation compared to whole cultured, control PANC-1 cells (WCC). PANC-1 invasion was reduced by nitric oxide synthase (NOS) inhibitors, suggesting that nitric oxide (NO) plays a cardinal role in PANC-1 invasion. Cell invasion through extracellular membrane (ECM) involves complex regulation of cell adhesion and de-adhesion to ECM proteins. Suspended INV cells, as well as INV cells undergoing de-adhesion, showed enhanced NO production as well as induction of several pro-metastatic, and stemness-related genes. NOS inhibitor, L-NAME, reduced the expression of these pro-metastatic or stemness-related genes, and hampered spheroid formation ability, suggesting that NO can potentially influence PANC-1 aggressiveness. In addition, in vitro studies indicated that a MEK-ERK-dependent, JAK-independent mechanism promoted NOS/NO modulation of PANC-1 invasion. Furthermore, xenograft studies with INV and WCC in an NSG mouse model revealed a higher ability of INV in liver metastasis than WCC, and L-NAME diminished the metastasis observed in INV injected mice. In summary, these results implicate NO as a key mediator of therapeutic resistance to Carbon-ion radiation and metastasis of PANC-1 cells; inhibition of NOS demonstrates therapeutic potential as observed in the animal model by specifically targeting the metastatic cells.

Citation Format: Mayumi Fujita, Veena Somasundaram, Debashree Basudhar Basudhar, Robert Y.s. Cheng, Lisa A. Ridnour, Kaori Imadome, Jae Hong No, Gaurav Bharadwaj, David A. Wink. Role of nitric oxide in the invasive pancreatic cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6071.

Abstract 2754: Inhibition of nitric oxide synthase and cyclooxygenase potentiate immune responses that control aggressive mammary tumor in a murine model

Progression of aggressive, triple negative breast cancers (TNBC) is driven by inflammation and the presence of tumor infiltrating lymphocytes (TIL) improves survival. Recent studies show that TNBCs show high levels of TILs but these cells are exhausted as evident from decreased IFNγ, Ki67 and granzyme B. High expression of the inflammation-associated protein, inducible nitric oxide synthase (NOS2) and co-expression with high cyclooxygenase 2 (COX2) means poor prognosis in ER- breast cancer. Interestingly, NOS2 and COX2 are upregulated in different cells in the tumor microenvironment (TME). Thus, we hypothesized that the tandem use of NOS2 and COX2 inhibitors would curtail tumor progression by targeting different cell types within the TME simultaneously. As COX2 has also been reported to regulate tumor infiltration of myeloid cells, this could regulate both the lymphoid and myeloid arms of the immune system for better response. We investigated the effects of NOS2 and COX2 on tumorigenesis and pulmonary metastasis in a murine model of TNBC by injecting 4T1 cells into the fourth mammary fat pad of wild type (WT) and NOS2 knockout (NOS2-/-) BALB/c mice followed by treatment with COX inhibitor, indomethacin. Changes in infiltrating immune cells was analyzed using flow cytometry and confocal microscopy. We measured the levels of serum cytokines using bead-based, LegendPlex assay. We found that NOS2-/- mice developed fewer pulmonary metastatic lesions than WT mice while indomethacin directly reduced primary tumor growth in both WT and NOS2-/- mice. Indomethacin treated NOS2-/- mice showed better median survival (60 days compared 51 in WT mice). Two NOS2-/-, indomethacin treated mice showed complete remission and long term (5-months) tumor growth delay after 4T1 re-challenge, indicating immune activation in mice lacking NOS2 and COX2 function. Flow cytometry of primary tumors showed higher infiltration of activated CD4, CD8 cells, macrophages and reduction of Tregs in treated mice. Microscopy revealed a physical ‘walling -off' of TILs by CD11b+ cells in untreated tumors that was abrogated upon indomethacin treatment. As many TNBC patients succumb to pulmonary metastasis and because we found reduced metastasis in NOS2-/- mice, we studied the immune cells in metastatic lungs. Lung niche of NOS2-/- mice had more activated T-cells, bone marrow-derived macrophages and neutrophils that are not conducive to establishment of metastasis. Serum of NOS2-/- mice had elevated IL-6 that drove increased IL17A subsequently contributing to reduced metastasis and this effect was improved upon indomethacin treatment. IL6 is also a potential inhibitor of Tregs thus further improving immune surveillance. COX inhibition can treat aggressive TNBC directly by reducing cancer cell proliferation and indirectly by immune activation. Tandem NOS2 inhibition can render the pulmonary microenvironment unfavorable for metastatic spread and induce a favorable systemic cytokine storm that further improves outcome.

Citation Format: Veena Somasundaram, Debashree Basudhar, Christopher McGinity, Robert Y. Cheng, Lisa A. Ridnour, Stephen J. Lockett, David A. Wink. Inhibition of nitric oxide synthase and cyclooxygenase potentiate immune responses that control aggressive mammary tumor in a murine model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2754.

Abstract 6198: Regulation of cycloxygenase-2 in the tumor micro-environment improves radiation and immunotherapy

In breast cancer (BC), the presence of tumor infiltrating lymphocytes is associated with improved survival. A recent study showed that increased CD8 cells and Th17 cells are specifically associated with triple negative breast cancer (TNBC) patients, a highly aggressive subclass of breast cancer. However, they undergo functional reprogramming in the tumor micro-environment(TME) evident from decreased IFN-γ;; and granzyme B. These immune escape mechanisms contribute to inability of the immune system to control tumor progression. Thus modulation of TME is necessary to effectively target the tumor. Radiation therapy (RT) is commonly used in more than 60% of cancer patients including BC. Focal radiation limits systemic side effects commonly associated with chemotherapy and acts as immune modulator. Eventually the tumor comes out of the growth delay and tends to show more aggressive phenotype. We found that RT induced inflammation associated biomarkers nitric oxide synthase2 (NOS2) and cycloxygenase2 (COX2) in the TME, specifically in the tumor cells.We previously showed that co-expression of pro-inflammatory enzymes NOS2 and COX2is a powerful prognostic indicator of poor outcome (HR=21) among ER-patients which in turn drive major oncogenic pathways. Immunotherapy, on the other hand, is being used as a standard of care in lung cancer. However, currently there is no approved immunotherapy available for BC patients, early data from several ongoing clinical trials show activity in various subclasses of BC including TNBC. It is reported that PD-L1 is high in 20% of TNBCs and COX2 may be involved in its regulation in tumor-infiltrating myeloid cells. This led us to hypothesize that modulation of inflammation associated biomarkers in the TME would increase the efficacy of RT and immunotherapy by amplifying anti-tumor immunity. We investigated the effect of NOS2 or COX2 inhibition using commercially available inhibitor on radiation and αPD-L1 induced tumor growth delay and lung metastases in murine model of TNBC using 4T1 cell line implanted in flank of Balbc mice. Change in immune cell populations in the TME was investigated using confocal microscopy, CO-Detection by indEXing (CODEX) technology and flow-cytometry. We also measured the levels of inflammation associated cytokines in serum. We demonstrated that co-treatment with COX2 inhibitor led to tumor growth delay and reduced metastases compared to conventional therapy by changing the TME to support tumor clearance.

Citation Format: Debashree Basudhar, Veena Somasundaram, David A. Scheiblin, Noemi Kedei, Robert Y. Cheng, Lisa A. Ridnour, Daniel W. McVicar, Stephen Lockett, David A. Wink. Regulation of cycloxygenase-2 in the tumor micro-environment improves radiation and immunotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6198.

A divergent mode of activation of a nitrosyl iron complex with unusual antiangiogenic activity

Nitric oxide (NO) and nitroxyl (HNO) have gained broad attention due to their roles in several physiological and pathophysiological processes. Remarkably, these sibling species can exhibit opposing effects including the promotion of angiogenic activity by NO compared to HNO, which blocks neovascularization. While many NO donors have been developed over the years, interest in HNO has led to the recent emergence of new donors. However, in both cases there is an expressive lack of iron-based compounds. Herein, we explored the novel chemical reactivity and stability of the trans-[Fe(cyclam)(NO)Cl]Cl₂ (cyclam = 1,4,8,11-tetraazacyclotetradecane) complex. Interestingly, the half-life (t_1/2) for NO release was 1.8 min upon light irradiation, vs 5.4 h upon thermal activation at 37 °C. Importantly, spectroscopic evidence supported the generation of HNO rather than NO induced by glutathione. Moreover, we observed significant inhibition of NO donor- or hypoxia-induced HIF-1α (hypoxia-inducible factor 1α) accumulation in breast cancer cells, as well as reduced vascular tube formation by endothelial cells pretreated with the trans-[Fe(cyclam)(NO)Cl]Cl₂ complex. Together, these studies provide the first example of an iron-nitrosyl complex with anti-angiogenic activity as well as the potential dual activity of this compound as a NO/HNO releasing agent, which warrants further pharmacological investigation.

Studying Triple Negative Breast Cancer Using Orthotopic Breast Cancer Model

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with limited therapeutic options. When compared to patients with less aggressive breast tumors, the 5-year survival rate of TNBC patients is 77% due to their characteristic drug-resistant phenotype and metastatic burden. Toward this end, murine models have been established aimed at identifying novel therapeutic strategies limiting TNBC tumor growth and metastatic spread. This work describes a practical guide for the TNBC orthotopic model where MDA-MB-231 breast cancer cells suspended in a basement membrane matrix are implanted in the fourth mammary fat pad, which closely mimics the cancer cell behavior in humans. Measurement of tumors by caliper, lung metastasis assessment via in vivo and ex vivo imaging, and molecular detection are discussed. This model provides an excellent platform to study therapeutic efficacy and is especially suitable for the study of the interaction between the primary tumor and distal metastatic sites.

Nitric oxide orchestrates metabolic rewiring in M1 macrophages by targeting aconitase 2 and pyruvate dehydrogenase

Profound metabolic changes are characteristic of macrophages during classical activation and have been implicated in this phenotype. Here we demonstrate that nitric oxide (NO) produced by murine macrophages is responsible for TCA cycle alterations and citrate accumulation associated with polarization. ¹³C tracing and mitochondrial respiration experiments map NO-mediated suppression of metabolism to mitochondrial aconitase (ACO2). Moreover, we find that inflammatory macrophages reroute pyruvate away from pyruvate dehydrogenase (PDH) in an NO-dependent and hypoxia-inducible factor 1α (Hif1α)-independent manner, thereby promoting glutamine-based anaplerosis. Ultimately, NO accumulation leads to suppression and loss of mitochondrial electron transport chain (ETC) complexes. Our data reveal that macrophages metabolic rewiring, in vitro and in vivo, is dependent on NO targeting specific pathways, resulting in reduced production of inflammatory mediators. Our findings require modification to current models of macrophage biology and demonstrate that reprogramming of metabolism should be considered a result rather than a mediator of inflammatory polarization.

Production of inflammatory mediators by M1-polarized macrophages is thought to rely on suppression of mitochondrial metabolism in favor of glycolysis. Refining this concept, here the authors define metabolic targets of nitric oxide as responsible for the mitochondrial rewiring resulting from polarization.

NO and hepatocellular cancer

NO has broad and sometimes dichotomous roles in cancer. The effects of NO in tumours depend on the type and localization of NOS isoforms, concentration and duration of NO exposure, and cellular sensitivity to NO. Hepatocellular carcinoma (HCC) is a common and lethal disease for which no effective therapy other than surgical resection exists. Over two decades of research has yielded evidence that NO generated by the inducible NOS (iNOS or NOS2) contributes to HCC progression in at least a subset of patients with HCC. The co-expression of iNOS with COX-2 may portend a particularly aggressive cancer phenotype in HCC and at the same time reveal an opportunity for pharmacological intervention. In this review, we focus on what is known about the influence of NO in HCC neoplastic transformation, proliferation and apoptosis, angiogenesis, invasion, and metastasis, cancer stem cells, and the host immune response against the tumour. We discuss the implications of recent findings for targeting the NO pathways in HCC.

Inducible nitric oxide synthase-derived extracellular nitric oxide flux regulates proinflammatory responses at the single cell level

The role of nitric oxide (NO) in cancer progression has largely been studied in the context of tumor NOS2 expression. However, pro- versus anti-tumor signaling is also affected by tumor cell-macrophage interactions. While these cell-cell interactions are partly regulated by NO, the functional effects of NO flux on proinflammatory (M1) macrophages are unknown. Using a triple negative murine breast cancer model, we explored the potential role of macrophage Nos2 on 4T1 tumor progression. The effects of NO on macrophage phenotype were examined in bone marrow derived macrophages from wild type and Nos2^−/− mice following in vitro stimulation with cytokine/LPS combinations to produce low, medium, and high NO flux. Remarkably, Nos2 induction was spatially distinct, where Nos2^high cells expressed low cyclooxygenase-2 (Cox2) and vice versa. Importantly, in vitro M1 polarization with IFNγ+LPS induced high NO flux that was restricted to cells harboring depolarized mitochondria. This flux altered the magnitude and spatial extent of hypoxic gradients. Metabolic and single cell analyses demonstrated that single cell Nos2 induction limited the generation of hypoxic gradients in vitro, and Nos2-dependent and independent features may collaborate to regulate M1 functionality. It was found that Cox2 expression was important for Nos2^high cells to maintain NO tolerance. Furthermore, Nos2 and Cox2 expression in 4T1 mouse tumors was spatially orthogonal forming distinct cellular neighborhoods. In summary, the location and type of Nos2^high cells, NO flux, and the inflammatory status of other cells, such as Cox2^high cells in the tumor niche contribute to Nos2 inflammatory mechanisms that promote disease progression of 4T1 tumors.

Nitric Oxide Donor DETA/NO Inhibits the Growth of Endometrial Cancer Cells by Upregulating the Expression of RASSF1 and CDKN1A

Nitric oxide (NO) is implicated in several biological processes, including cancer progression. At low concentrations, it promotes cell survival and tumor progression, and at high concentrations it causes apoptosis and cell death. Until now, the impact of NO donors has not been investigated on human endometrial tumors. Four cancer cell lines were exposed to different concentrations of DETA/NO for 24 to 120 h. The effects of DETA/NO on cell proliferation and invasion were determined utilizing MTS and Boyden chamber assays, respectively. The DETA/NO induced a dose and time-dependent reduction in cell viability by the activation of caspase-3 and cell cycle arrest at the G0/G1 phase that was associated with the attenuated expression of cyclin-D1 and D3. Furthermore, the reduction in the amount of CD133-expressing cancer stem-like cell subpopulation was observed following DETA/NO treatment of cells, which was associated with a decreased expression of stem cell markers and attenuation of cell invasiveness. To understand the mechanisms by which DETA/NO elicits anti-cancer effects, RNA sequencing (RNA-seq) was used to ascertain alterations in the transcriptomes of human endometrial cancer cells. RNA-seq analysis revealed that 14 of the top 21 differentially expressed genes were upregulated and seven were downregulated in endometrial cancer cells with DETA/NO. The genes that were upregulated in all four cell lines with DETA/NO were the tumor suppressors Ras association domain family 1 isoform A (RASSF1) and Cyclin-dependent kinase inhibitor 1A (CDKN1A). The expression patterns of these genes were confirmed by Western blotting. Taken together, the results provide the first evidence in support of the anti-cancer effects of DETA/NO in endometrial cancer.

Abstract 1186: Regulation of inducible nitric oxide synthase at the single cell level modulates the inflammatory microenvironment

The anti-cancer versus pro-tumor behavior of cancer tissues is dependent largely on tumor cell-macrophage interactions in the tumor/inflammatory microenvironment and is regulated by Nitric Oxide (NO). High inducible nitric oxide synthase (Nos2) is associated with poor prognosis in breast cancer. Previously, we found that murine macrophages can be activated by different inflammatory cytokines/LPS to produce distinct NO fluxes (entirely Nos2-derived), suggesting flux-specific biological ramifications of NO. However, the effects of these NO fluxes on M1 phenotype have not been delineated. LC/MS analysis of M1 stimulated, wild type (wt) and Nos2-/- macrophages showed that Nos2 was the only source of citrulline. Metabolic analyses and microscopy showed that flattened cell phenotype characteristic of M1 macrophages and mitochondrial respiration are Nos2 dependent and regulated in a NO flux-dependent manner, while proinflammatory cytokine profile and aerobic glycolysis are Nos2 independent. We show for the first time that induction of Nos2 expression occurs only in specific stimulated cells that also harbor depolarized mitochondria. NO production has been linked to decreased oxygen consumption in hypoxic environments. We utilized a novel, in vitro chamber system that forms cell-generated hypoxic and metabolic gradients in two-dimensions by restricting the diffusive exchange of oxygen and metabolites to a monolayer of cells in a small volume- analogous to diffusion between a capillary and nearby tissue. We investigated interactions between Nos2 in M1-stimulated macrophages and hypoxia and demonstrated that treatment with IFNγ+LPS increases Nos2 expression and alters the magnitude and spatial extent of hypoxic gradients. A modified scratch assay revealed that low doses (1-50μM) of NO increased and high doses (1000μM) inhibited the migratory capacity of 4T1 tumor cells. However, in vivo, Nos2-/- mice did not show difference in primary tumor or metastatic burden compared to wt mice but bone marrow derived macrophages (BMDMs) from wt tumor bearing mice produced significantly lower levels of NO compared to BMDMs from tumor bearing- Nos2-/- mice. In summary, we find that the right flux NO is required to tune the inflammatory microenvironment. Nos2 and citrulline are robust intracellular readouts of extracellular NO flux. Nos2 dependent and independent events cooperate to regulate inflammatory macrophages. Autocrine, single cell effects on metabolism build up to cause paracrine effects including alleviation of hypoxia. 4T1 primary tumor and lung metastasis were not Nos2-regulated but host Nos2 hampered the ability of BMDMs to respond to proinflammatory stimuli hinting at possible systemic effects of Nos2. Hence, to make a reliable prognostic prediction, it is important to know the exact NO flux, which cells within the tumor express Nos2 and what other cells associate with Nos2hi cells.

Citation Format: Veena Somasundaram, Caroline Gilmore, Erika M. Palmieri, Debashree Basudhar, Will Heinz, Robert Y. Cheng, Lisa A. Ridnour, Stephen J. Lockett, Daniel W. McVicar, David A. Wink. Regulation of inducible nitric oxide synthase at the single cell level modulates the inflammatory microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1186.

Molecular Mechanisms of Nitric Oxide in Cancer Progression, Signal Transduction, and Metabolism

SIGNIFICANCE

Cancer is a complex disease, which not only involves the tumor but its microenvironment comprising different immune cells as well. Nitric oxide (NO) plays specific roles within tumor cells and the microenvironment and determines the rate of cancer progression, therapy efficacy, and patient prognosis. Recent Advances: Key understanding of the processes leading to dysregulated NO flux within the tumor microenvironment over the past decade has provided better understanding of the dichotomous role of NO in cancer and its importance in shaping the immune landscape. It is becoming increasingly evident that nitric oxide synthase 2 (NOS2)-mediated NO/reactive nitrogen oxide species (RNS) are heavily involved in cancer progression and metastasis in different types of tumor. More recent studies have found that NO from NOS2⁺ macrophages is required for cancer immunotherapy to be effective.

CRITICAL ISSUES

NO/RNS, unlike other molecules, are unique in their ability to target a plethora of oncogenic pathways during cancer progression. In this review, we subcategorize the different levels of NO produced by cells and shed light on the context-dependent temporal effects on cancer signaling and metabolic shift in the tumor microenvironment.

FUTURE DIRECTIONS

Understanding the source of NO and its spaciotemporal profile within the tumor microenvironment could help improve efficacy of cancer immunotherapies by improving tumor infiltration of immune cells for better tumor clearance.

Role of nitric oxide in pancreatic cancer cells exhibiting the invasive phenotype

Pancreatic cancer is a highly metastatic tumor with an extremely low 5-year survival rate. Lack of efficient diagnostics and dearth of effective therapeutics that can target the cancer as well as the microenvironment niche are the reasons for limited success in treatment and management of this disease. Cell invasion through extracellular matrix (ECM) involves the complex regulation of adhesion to and detachment from ECM and its understanding is critical to metastatic potential of pancreatic cancer. To understand the characteristics of these cancer cells and their ability to metastasize, we compared human pancreatic cancer cell line, PANC-1 and its invading phenotype (INV) collected from transwell inserts. The invasive cell type, INV, exhibited higher resistance to Carbon-ion radiation compared to whole cultured (normally dish-cultured) PANC-1 (WCC), and had more efficient in vitro spheroid formation capability. Invasiveness of INV was hampered by nitric oxide synthase (NOS) inhibitors, suggesting that nitric oxide (NO) plays a cardinal role in PANC-1 invasion. In addition, in vitro studies indicated that a MEK-ERK-dependent, JAK independent mechanism through which NOS/NO modulate PANC-1 invasiveness. Suspended INV showed enhanced NO production as well as induction of several pro-metastatic, and stemness-related genes. NOS inhibitor, l-NAME, reduced the expression of these pro-metastatic or stemness-related genes, and dampened spheroid formation ability, suggesting that NO can potentially influence pancreatic cancer aggressiveness. Furthermore, xenograft studies with INV and WCC in NSG mouse model revealed a greater ability of INV compared to WCC, to metastasize to the liver and l-NAME diminished the metastatic lesions in mice injected with INV. Overall, data suggest that NO is a key player associated with resistance to radiation and metastasis of pancreatic cancer; and inhibition of NOS demonstrates therapeutic potential as observed in the animal model by specifically targeting the metastatic cells that harbor stem-like features and are potentially responsible for relapse.

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Highly invasive pancreatic cancer cell line, collected from transwell inserts showed increased resistance to C-ion radiation.

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NO is a key player in pancreatic cancer aggressiveness inducing pro-metastatic and stemness-related genes.

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NOS/NO modulate invasiveness through a MEK-ERK dependent, JAK signaling independent mechanism.

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NOS inhibition showed promising therapeutic potential in mouse model by reversing the pro-metastatic phenotype.

Understanding the tumour micro-environment communication network from an NOS2/COX2 perspective

Recent findings suggest that co-expression of NOS2 and COX2 is a strong prognostic indicator in triple-negative breast cancer patients. These two key inflammation-associated enzymes are responsible for the biosynthesis of NO and PGE2 , respectively, and can exert their effect in both an autocrine and paracrine manner. Impairment of their physiological regulation leads to critical changes in both intra-tumoural and intercellular communication with the immune system and their adaptation to the hypoxic tumour micro-environment. Recent studies have also established a key role of NOS2-COX2 in causing metabolic shift. This review provides an extensive overview of the role of NO and PGE2 in shaping communication between the tumour micro-environment composed of tumour and immune cells that in turn favours tumour progression and metastasis. LINKED ARTICLES: This article is part of a themed section on Nitric Oxide 20 Years from the 1998 Nobel Prize. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.2/issuetoc.

Itaconic acid mediates crosstalk between macrophage metabolism and peritoneal tumors

Control of cellular metabolism is critical for efficient cell function, although little is known about the interplay between cell subset–specific metabolites in situ, especially in the tumor setting. Here, we determined how a macrophage-specific (Mϕ-specific) metabolite, itaconic acid, can regulate tumor progression in the peritoneum. We show that peritoneal tumors (B16 melanoma or ID8 ovarian carcinoma) elicited a fatty acid oxidation–mediated increase in oxidative phosphorylation (OXPHOS) and glycolysis in peritoneal tissue–resident macrophages (pResMϕ). Unbiased metabolomics identified itaconic acid, the product of immune-responsive gene 1–mediated (Irg1-mediated) catabolism of mitochondrial cis-aconitate, among the most highly upregulated metabolites in pResMϕ of tumor-bearing mice. Administration of lentivirally encoded Irg1 shRNA significantly reduced peritoneal tumors. This resulted in reductions in OXPHOS and OXPHOS-driven production of ROS in pResMϕ and ROS-mediated MAPK activation in tumor cells. Our findings demonstrate that tumors profoundly alter pResMϕ metabolism, leading to the production of itaconic acid, which potentiates tumor growth. Monocytes isolated from ovarian carcinoma patients’ ascites fluid expressed significantly elevated levels of IRG1. Therefore, IRG1 in pResMϕ represents a potential therapeutic target for peritoneal tumors.

Abstract 3789: Role of NOS2-COX2 crosstalk in tumor microenvironment of estrogen receptor-negative breast cancer and its therapeutic implications

Tumor is often described as a wound that never heals. This leads to a chronic inflammatory tumor microenvironment characterized by infiltration of M2 macrophages and Th2 cells causing dysregulated release of multiple cytokines, chemokines and growth factors, thus creating a conducive environment for tumor growth and metastasis. In spite of significant progress in breast cancer treatment, metastatic breast cancer still remains a major health hazard with a high mortality rate among women. Moreover, there is cellular heterogeneity within and among different breast tumors, which poses a significant challenge in developing effective therapeutics, thus making it important to understand subtype-specific mechanisms. Our laboratory and other groups have previously shown that inducible nitric oxide synthase (NOS2), an enzyme involved in production and regulation of endogenous nitric oxide (NO), is a predictor of poor survival among highly metastatic ER-negative (ER-) breast cancer patients. Another proinflammatory enzyme, cyclooxygenase-2 (COX2,) responsible for conversion of arachidonic acid to prostaglandin E2 (PGE2), is also highly expressed in breast cancer and is detectable in ductal carcinoma in situ, invasive breast carcinoma, and metastatic lesions. We investigated the role of inflammation associated enzymes, NOS2 and COX2, and established that their simultaneous elevated expression significantly reduced patient survival (33%) when compared to greater than 95% survival of ER- patients with low NOS2/COX2 tumor expression. We further investigated their tumor subtype specific novel signaling mechanism in vitro and showed TNFα and/or endoplasmic reticulum stress as key players. Proinflammatory cytokines present in tumor microenvironment play a key role in regulation of this pathway and effectiveness of chemotherapeutics. Moreover, the ability of NOS2 and COX2 to regulate different cytokines in the tumor microenvironment further emphasizes the importance of their crosstalk in tumor progression, metastasis and ability of cancer cells to escape immune surveillance. Last, we demonstrated that simultaneous inhibition of COX2 and NOS2 using commercially available inhibitors significantly reduced tumor growth in murine models of ER- breast cancer, thus suggesting the beneficial effects of dual NOS2/COX2 therapy.

Citation Format: Debashree Basudhar, Sharon Glynn, Madison Greer, Veena Somasundaram, Jae H. No, David A. Scheiblin, Pablo Garrido, William F. Heinz, Aideen E. Ryan, Jonathan M. Weiss, Robert Y. Cheng, Lisa A. Ridnour, Stephen J. Lockett, Daniel W. McVicar, Stefan Ambs, David A. Wink. Role of NOS2-COX2 crosstalk in tumor microenvironment of estrogen receptor-negative breast cancer and its therapeutic implications [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 3789.

Abstract 5500: Nitric oxide donor DETA/NO inhibits the growth of endometrial cancer cells by upregulating expression of RASSF1 and CDKN1

Nitric oxide (NO), a small signaling molecule, is implicated in several biological processes including cancer progression. At low concentrations, it promotes cell survival and tumor progression, and at high concentrations it causes apoptosis and cell death. To date, the effects of NO donor on human endometrial cancer are largely unknown. Four endometrial cancer cell lines (Ishikawa, AN3CA, KLE and HEC-1B) with varying degrees of genetic complexity were treated with different concentrations (50-500 μM) of DETA/NO for 24 to 120 h. The effects of treatment on cell viability and invasion was determined using MTS, and Boyden chamber assays respectively. Treatment of endometrial cancer cells with DETA/NO induced a dose and time-dependent decrease in cell viability. Ishikawa and AN3CA cells were more responsive to DETA/NO induced growth inhibition compared to HEC-1B and KLE cells. Furthermore, DETA/NO effectively inhibited invasive potential of endometrial cancer cells. To understand the mechanisms by which DETA/NO elicits anti-cancer effects, RNA sequencing (RNA-seq) was used to ascertain alterations in the transcriptomes of human endometrial cancer cells. AN3CA, KLE, Ishikawa, and HEC-1B were treated with DETA/NO for 24 h and RNA was extracted. RNA-seq analysis revealed that of the twenty-one top differentially expressed genes, fourteen were upregulated and seven were downregulated in endometrial cancer cells with DETA/NO. The genes that were upregulated in all four cell lines with DETA/NO were tumor suppressors, RASSF1 and CDKN1A. The expression patterns of these genes were confirmed by Western blotting. Taken together, the results provide the first evidence in support of the anti-cancer effects of DETA/NO in endometrial cancer.

Citation Format: Hannah Taitz, Ana Paucarmayta, Robert Cheng, George L. Maxwell, Chad A. Hamilton, David A. Wink, Viqar Syed. Nitric oxide donor DETA/NO inhibits the growth of endometrial cancer cells by upregulating expression of RASSF1 and CDKN1 [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 5500.

Biological hydropersulfides and related polysulfides - a new concept and perspective in redox biology

The chemical biology of thiols (RSH, e.g., cysteine and cysteine-containing proteins/peptides) has been a topic of extreme interest for many decades due to their reported roles in protein structure/folding, redox signaling, metal ligation, cellular protection, and enzymology. While many of the studies on thiol/sulfur biochemistry have focused on thiols, relatively ignored have been hydropersulfides (RSSH) and higher order polysulfur species (RSS_n H, RSS_n R, n > 1). Recent and provocative work has alluded to the prevalence and likely physiological importance of RSSH and related RSS_n H. RSSH of cysteine (Cys-SSH) has been found to be prevalent in mammalian systems along with Cys-SSH-containing proteins. The RSSH functionality has not been examined to the extent of other biologically relevant sulfur derivatives (e.g., sulfenic acids, disulfides, etc.), whose roles in cell signaling are strongly indicated. The recent finding of Cys-SSH biosynthesis and translational incorporation into proteins is an unequivocal indication of its fundamental importance and necessitates a more profound look into the physiology of RSSH. In this Review, we discuss the currently reported chemical biology of RSSH (and related species) as a prelude to discussing their possible physiological roles.

Nitric oxide dictates the reprogramming of carbon flux during M1 macrophage polarization

Classical pro-inflammatory activation of macrophages is characterized by profound intracellular metabolic changes, with increased glycolytic usage of carbon, away from Oxidative Phosphorylation (OXPHOS). We previously demonstrated that Nitric Oxide (NO) levels induced in Bone Marrow Derived Macrophages (BMDMs) from Wild Type (WT) mice are necessary and sufficient for the repression of OXPHOS. Here we demonstrate that NO is also responsible for the “break” in the mitochondrial TCA cycle and citrate accumulation during LPS/IFNγ stimulation; macrophages that lack NO maintain indeed substantial levels of Oxygen Consumption Rates (OCR) and TCA cycle intermediates. Carbon tracing experiments in the presence of U13C-glucose show almost undetected labelled α-ketoglutarate from citrate in WT but a conserved pattern of heavy carbon fate in Nos2−/− macrophages. Moreover we found that mitochondrial respiration elicited through citrate was decreased in WT M1 macrophages, but isocitrate was a full substrate for complex I-dependent OCR suggesting suppression of metabolism at mitochondrial Aconitase (ACO2). Consistent with this data, we found ACO2 enzymatic activity blunted in WT vs Nos2−/−. In addition we observed that M1 macrophages reroute pyruvate away from Pyruvate Dehydrogenase (PDH) in an NO dependent manner since only WT show halted flux through PDH. Surprisingly, we demonstrate this mechanism to be independent on the activation of Hif1α and its suggested effect on limiting acetyl-coA for the TCA. With these data together we hypothesize that NO orchestrates macrophage metabolism during inflammation inhibiting OXPHOS by blocking Krebs Cycle, therefore depriving of substrates the mitochondrial electron transport chain.

Design, synthesis and biological evaluation of hybrid nitroxide-based non-steroidal anti-inflammatory drugs

Dual-acting hybrid anti-oxidant/anti-inflammatory agents were developed employing the principle of pharmacophore hybridization. Hybrid agents were synthesized by combining stable anti-oxidant nitroxides with conventional non-steroidal anti-inflammatory drugs (NSAIDs). Several of the hybrid nitroxide-NSAID conjugates displayed promising anti-oxidant and anti-inflammatory effects on two Non-Small Cell Lung Cancer (NSCLC) cells (A549 and NCI-H1299) and in ameliorating oxidative stress induced in 661 W retinal cells. One ester-linked nitroxide-aspirin analogue (27) delivered better anti-inflammatory effects (cyclooxygenase inhibition) than the parent compound (aspirin), and also showed similar reactive oxygen scavenging activity to the anti-oxidant, Tempol. In addition, a nitroxide linked to the anti-inflammatory drug indomethacin (39) significantly ameliorated the effects of oxidative stress on 661 W retinal neurons at efficacies greater or equal to the anti-oxidant Lutein. Other examples of the hybrid conjugates displayed promising anti-cancer activity, as demonstrated by their inhibitory effects on the proliferation of A549 NSCLC cells.

The Reactive Species Interactome: Evolutionary Emergence, Biological Significance, and Opportunities for Redox Metabolomics and Personalized Medicine

SIGNIFICANCE

Oxidative stress is thought to account for aberrant redox homeostasis and contribute to aging and disease. However, more often than not, administration of antioxidants is ineffective, suggesting that our current understanding of the underlying regulatory processes is incomplete. Recent Advances: Similar to reactive oxygen species and reactive nitrogen species, reactive sulfur species are now emerging as important signaling molecules, targeting regulatory cysteine redox switches in proteins, affecting gene regulation, ion transport, intermediary metabolism, and mitochondrial function. To rationalize the complexity of chemical interactions of reactive species with themselves and their targets and help define their role in systemic metabolic control, we here introduce a novel integrative concept defined as the reactive species interactome (RSI). The RSI is a primeval multilevel redox regulatory system whose architecture, together with the physicochemical characteristics of its constituents, allows efficient sensing and rapid adaptation to environmental changes and various other stressors to enhance fitness and resilience at the local and whole-organism level.

CRITICAL ISSUES

To better characterize the RSI-related processes that determine fluxes through specific pathways and enable integration, it is necessary to disentangle the chemical biology and activity of reactive species (including precursors and reaction products), their targets, communication systems, and effects on cellular, organ, and whole-organism bioenergetics using system-level/network analyses.

FUTURE DIRECTIONS

Understanding the mechanisms through which the RSI operates will enable a better appreciation of the possibilities to modulate the entire biological system; moreover, unveiling molecular signatures that characterize specific environmental challenges or other forms of stress will provide new prevention/intervention opportunities for personalized medicine. Antioxid. Redox Signal. 00, 000-000.

Nitric Oxide Synthase-2-Derived Nitric Oxide Drives Multiple Pathways of Breast Cancer Progression

SIGNIFICANCE

Breast cancer is the second leading cause of cancer-related deaths among women in the United States. Development and progression of malignancy are associated with diverse cell signaling pathways that control cell proliferation, survival, motility, invasion, and metastasis. Recent Advances: An increasing number of clinical studies have implicated a strong relationship between elevated tumor nitric oxide synthase-2 (NOS2) expression and poor patient survival.

CRITICAL ISSUES

Herein, we review what we believe to be key mechanisms in the role(s) of NOS2-derived nitric oxide (NO) as a driver of breast cancer disease progression. High NO increases cyclooxygenase-2 activity, hypoxia inducible factor-1 alpha protein stabilization, and activation of important cell signaling pathways, including phosphoinositide 3-kinase/protein kinase B, mitogen-activated protein kinase, epidermal growth factor receptor, and Ras, through post-translational protein modifications. Moreover, dysregulated NO flux within the tumor microenvironment has other important roles, including the promotion of angiogenesis and modulation of matrix metalloproteinase/tissue inhibitor matrix metalloproteinase associated with tumor progression.

FUTURE DIRECTIONS

The elucidation of these and other NO-driven pathways implicates NOS2 as a key driver of breast cancer disease progression and provides a new perspective in the identification of novel targets that may be therapeutically beneficial in the treatment of estrogen receptor-negative disease. Antioxid. Redox Signal. 26, 1044-1058.

Inducible Nitric Oxide Synthase in the Carcinogenesis of Gastrointestinal Cancers

SIGNIFICANCE

Gastrointestinal (GI) cancer taken together constitutes one of the most common cancers worldwide with a broad range of etiological mechanisms. In this review, we have examined the impact of nitric oxide (NO) on the etiology of colon, colorectal, gastric, esophageal, and liver cancers. Recent Advances: Despite differences in etiology, initiation, and progression, chronic inflammation has been shown to be a common element within these cancers showing interactions of numerous pathways. NO generated at the inflammatory site contributes to the initiation and progression of disease. The amount of NO generated, time, and site vary and are an important determinant of the biological effects initiated. Among the nitric oxide synthase enzymes, the inducible isoform has the most diverse range, participating in numerous carcinogenic processes. There is emerging evidence showing that inducible nitric oxide synthase (NOS2) plays a central role in the process of tumor initiation and/or development.

CRITICAL ISSUES

Redox inflammation through NOS2 and cyclooxygenase-2 participates in driving the mechanisms of initiation and progression in GI cancers.

FUTURE DIRECTIONS

Understanding the underlying mechanism involved in NOS2 activation can provide new insights into important prevention and treatment strategies. Antioxid. Redox Signal. 26, 1059-1077.

NOS2 as an Emergent Player in Progression of Cancer

Although the inducible form of nitric oxide synthase (NOS2) was initially shown to be a major player as an antitumor component of the immune response, more recent data have shown that NOS2 expression in cancer cells often predicts poor outcome. Unlike growth factors associated with a single oncogenic pathway, nitric oxide (NO) has a ubiquitous nature wherein it simultaneously mediates major oncogenic pathways from Akt/PI3K and RAS/ERK to HIF1a and TGFb. These interactive loops perpetuate oncogenic mechanism that leads to increased cancer stemness, proliferation metastasis, chemoresistance, angiogenesis, and immunosuppression. Examination of a wide variety of patient tumors demonstrates that NOS2 expression is >50% for most cancers. In many cases, elevated NOS2 has been shown to predict poor outcome in cancer such as ER- breast cancer, glioma, melanoma, cervical, liver, ovarian, and pancreatic. Taken together, NOS2 may be one of the most powerful biomarker and predictors of poor prognosis and an ideal target for cancer therapy. Antioxid. Redox Signal. 26, 963-965.

Autocrine IL-10 functions as a rheostat for M1 macrophage glycolytic commitment by tuning nitric oxide production

Inflammatory maturation of M1 macrophages by proinflammatory stimuli such as toll like receptor ligands results in profound metabolic reprogramming resulting in commitment to aerobic glycolysis as evidenced by repression of mitochondrial oxidative phosphorylation (OXPHOS) and enhanced glucose utilization. In contrast, "alternatively activated" macrophages adopt a metabolic program dominated by fatty acid-fueled OXPHOS. Despite the known importance of these developmental stages on the qualitative aspects of an inflammatory response, relatively little is know regarding the regulation of these metabolic adjustments. Here we provide evidence that the immunosuppressive cytokine IL-10 defines a metabolic regulatory loop. Our data show for the first time that lipopolysaccharide (LPS)-induced glycolytic flux controls IL-10-production via regulation of mammalian target of rapamycin (mTOR) and that autocrine IL-10 in turn regulates macrophage nitric oxide (NO) production. Genetic and pharmacological manipulation of IL-10 and nitric oxide (NO) establish that metabolically regulated autocrine IL-10 controls glycolytic commitment by limiting NO-mediated suppression of OXPHOS. Together these data support a model where autocine IL-10 production is controlled by glycolytic flux in turn regulating glycolytic commitment by preserving OXPHOS via suppression of NO. We propose that this IL-10-driven metabolic rheostat maintains metabolic equilibrium during M1 macrophage differentiation and that perturbation of this regulatory loop, either directly by exogenous cellular sources of IL-10 or indirectly via limitations in glucose availability, skews the cellular metabolic program altering the balance between inflammatory and immunosuppressive phenotypes.

Thiol-Activated HNO Release from a Ruthenium Antiangiogenesis Complex and HIF-1α Inhibition for Cancer Therapy

Metallonitrosyl complexes are promising as nitric oxide (NO) donors for the treatment of cardiovascular, endothelial, and pathogenic diseases, as well as cancer. Recently, the reduced form of NO^– (protonated as HNO, nitroxyl, azanone, isoelectronic with O₂) has also emerged as a candidate for therapeutic applications including treatment of acute heart failure and alcoholism. Here, we show that HNO is a product of the reaction of the Ru^II complex [Ru(bpy)₂(SO₃)(NO)]⁺ (1) with glutathione or N-acetyl-L-cysteine, using met-myoglobin and carboxy-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) as trapping agents. Characteristic absorption spectroscopic profiles for HNO reactions with met-myoglobin were obtained, as well as EPR evidence from carboxy-PTIO experiments. Importantly, the product HNO counteracted NO-induced as well as hypoxia-induced stabilization of the tumor-suppressor HIF-1α in cancer cells. The functional disruption of neovascularization by HNO produced by this metallonitrosyl complex was demonstrated in an in vitro angiogenesis model. This behavior is consistent with HNO biochemistry and contrasts with NO-mediated stabilization of HIF-1α. Together, these results demonstrate for the first time thiol-dependent production of HNO by a ruthenium complex and subsequent destabilization of HIF-1α. This work suggests that the complex warrants further investigation as a promising antiangiogenesis agent for the treatment of cancer.

Review of Triple Negative Breast Cancer and the Impact of Inducible Nitric Oxide Synthase on Tumor Biology and Patient Outcomes

Triple negative breast cancers (TNBCs), which are defined as estrogen-receptor, progesterone-receptor, and HER2-receptor negative, account for 10-20% of breast cancers, and they are associated with early metastasis, chemotherapeutic resistance, and poor survival rates. One aspect of TNBC that complicates its prognosis and the development of new molecular therapeutic targets is its clinical and molecular heterogeneity. Herein we compare TNBC and basal cytokeratin-positive breast cancers. We examine the different TNBC molecular subtypes, based on gene expression profiling, which include basal-like, mesenchymal, and luminal androgen receptors, in the context of their biology and impact on TNBC prognosis. We explore the potential role of inducible nitric oxide synthase (iNOS) in TNBC tumor biology and treatment responses. iNOS has been shown to induce p53 mutation accumulation, basal-like gene signature enrichment, and transactivation of the epidermal growth factor receptor (EGFR) via S-nitrosylation, all of which are key components of TNBC biology. Moreover, iNOS predicts poor outcome in TNBC, and iNOS inhibitors show efficacy against TNBC when used in combination with chemotherapy. We discuss molecular targeted approaches, including EGFR, PARP, and VEGF inhibitors and immunotherapeutics, that are under consideration for the treatment of TNBC and what role, if any, iNOS may play in their success.

Biological signaling by small inorganic molecules

Small redox active molecules such as reactive nitrogen and oxygen species and hydrogen sulfide have emerged as important biological mediators that are involved in various physiological and pathophysiological processes. Advancement in understanding of cellular mechanisms that tightly regulate both generation and reactivity of these molecules is central to improved management of various disease states including cancer and cardiovascular dysfunction. Imbalance in the production of redox active molecules can lead to damage of critical cellular components such as cell membranes, proteins and DNA and thus may trigger the onset of disease. These small inorganic molecules react independently as well as in a concerted manner to mediate physiological responses. This review provides a general overview of the redox biology of these key molecules, their diverse chemistry relevant to physiological processes and their interrelated nature in cellular signaling.

The Oncogenic Properties Of The Redox Inflammatory Protein Inducible Nitric Oxide Synthase In ER(-) Breast Cancer

Inflammation generates reactive chemical species that induce conditions of oxidative nitrosative stress as emerged as factor in poor outcome of many cancers. Our recent findings show that in the inflammatory protein inducible nitric oxide synthase (iNOS) is a strong predictor of poor outcome in ER(-) patients (Glynn et al. JCI 2010). Furthermore 46 genes, of which 23 were associated with basal like breast cancer, were elevated when iNOS high. In vitro studies using ER(-) cell lines showed that fluxes of nitric oxide (NO) delivered by NO donors surprising mimic this relationship in the patient cohort. Using this model, we show that NO at different specific concentrations stimulate pro-oncogenic mechanisms such as AKT, ERK, NFkB, AP-1, and HIF-1α that lead to increase of metastatic and cancer stem cells proteins. In addition, we show that tumor suppressor gene BRCA1 and PP2A are inhibited by these NO levels. Similarly other studies show that these concentrations of NO increase immunosuppressive proteins TGF-β and IL-10 in leukocytes to decrease efficacy of some anticancer therapies further contributing to pro-tumorigenic environment. Using this model we have identified several new compounds that have efficacy in xenographic models. These finding have provided a model that shows how NO can affect numerous mechanism that leads to a more aggressive phenotype.

Signaling and stress: The redox landscape in NOS2 biology

Nitric oxide (NO) has a highly diverse range of biological functions from physiological signaling and maintenance of homeostasis to serving as an effector molecule in the immune system. However, deleterious as well as beneficial roles of NO have been reported. Many of the dichotomous effects of NO and derivative reactive nitrogen species (RNS) can be explained by invoking precise interactions with different targets as a result of concentration and temporal constraints. Endogenous concentrations of NO span five orders of magnitude, with levels near the high picomolar range typically occurring in short bursts as compared to sustained production of low micromolar levels of NO during immune response. This article provides an overview of the redox landscape as it relates to increasing NO concentrations, which incrementally govern physiological signaling, nitrosative signaling and nitrosative stress-related signaling. Physiological signaling by NO primarily occurs upon interaction with the heme protein soluble guanylyl cyclase. As NO concentrations rise, interactions with nonheme iron complexes as well as indirect modification of thiols can stimulate additional signaling processes. At the highest levels of NO, production of a broader range of RNS, which subsequently interact with more diverse targets, can lead to chemical stress. However, even under such conditions, there is evidence that stress-related signaling mechanisms are triggered to protect cells or even resolve the stress. This review therefore also addresses the fundamental reactions and kinetics that initiate signaling through NO-dependent pathways, including processes that lead to interconversion of RNS and interactions with molecular targets.

CD47 Receptor Globally Regulates Metabolic Pathways That Control Resistance to Ionizing Radiation

Modulating tissue responses to stress is an important therapeutic objective. Oxidative and genotoxic stresses caused by ionizing radiation are detrimental to healthy tissues but beneficial for treatment of cancer. CD47 is a signaling receptor for thrombospondin-1 and an attractive therapeutic target because blocking CD47 signaling protects normal tissues while sensitizing tumors to ionizing radiation. Here we utilized a metabolomic approach to define molecular mechanisms underlying this radioprotective activity. CD47-deficient cells and cd47-null mice exhibited global advantages in preserving metabolite levels after irradiation. Metabolic pathways required for controlling oxidative stress and mediating DNA repair were enhanced. Some cellular energetics pathways differed basally in CD47-deficient cells, and the global declines in the glycolytic and tricarboxylic acid cycle metabolites characteristic of normal cell and tissue responses to irradiation were prevented in the absence of CD47. Thus, CD47 mediates signaling from the extracellular matrix that coordinately regulates basal metabolism and cytoprotective responses to radiation injury.

Abstract 4140: Role of nitric oxide in invasiveness of tumor cells irradiated with carbon-ion beams

We previously reported that carbon-ion (C-ion) irradiation suppresses the invasiveness of several pancreatic cancer cell lines such as MIAPaCa-2, BxPC-3, and AsPC-1; however, we also observed that C-ion irradiation enhanced PANC-1 invasion. Most invading PANC-1 cells were nitric oxide (NO)-producing cells; the NOS-NO-PI3K-AKT pathway was activated in these cells. In addition, the actin-binding AKT substrate, Girdin, which modulates the actin organization and has important role in AKT-dependent cell motility, was activated and co-localized with p-AKT at the lamellipodia. C-ion irradiation increased the NO-producing cell population, thereby enhancing C-ion irradiation-enhanced PANC-1 invasion. In contrast to PANC-1 cells, NO levels as well as the number of NO-producing cells were decreased in C-ion irradiated MIAPaCa-2, indicated that the NO reduction might cause the suppression of MIAPaCa-2 invasion. The aim of this study is to clarify the role of NO in altered invasiveness of C-ion irradiated tumor cells. Treatment of PANC-1 with NO donor, DETA/NO, enhanced PANC-1 invasion. Interestingly, DETA/NO also increased MIAPaCa-2 invasion, indicated that NO contributes to the enhancement of MIAPaCa-2 invasiveness. The reduced invasiveness of C-ion irradiated MIAPaCa-2 was slightly but significantly recovered by the treatment with DETA/NO, but the recovered levels were still much less than the invasiveness of non-irradiated MIAPaCa-2. Thus, the reduction of NO levels involves in the decreased invasiveness of C-ion irradiated MIAPaCa-2, but there are additional factor regulating the invasiveness of cells irradiated with C-ion beams. Indeed, C-ion irradiation reduced GTP-Rac1 and GTP-RhoA expression, the active form of Rac1 and RhoA, which are known as two master regulators of cell motility. The reduction of GTP-Rac1 or GTP-RhoA was recovered by the treatment of proteasome inhibitor, indicated that those proteins were undergo degradation via the ubiquitin-proteasome pathway. So far, IAPs, Inhibitors of Apoptosis Proteins, and HACE1, HECT-domain containing E3 ubiquitin-ligase, were reported as direct E3 ubiquitin ligase of Rac1. Of those, XIAP was selectively induced and was co-precipitated with GTP-Rac1 in C-ion irradiated MIAPaCa-2. In conclusion, NO has a significant role in enhancing invasive potential of both PANC-1 and MIAPaCa-2 cells. The alteration of NO levels upon C-ion irradiation modulates the invasiveness of irradiated cells. Also, reductions of GTP-Rac1 and GTP-RhoA have the additional effects on the C-ion reduced MIAPaCa-2 invasion. Several studies have reported that NO modulates ubiquitin-proteasomal degradation of proteins. The effect of NO on the GTP-Rac1 and GTP-RhoA degradation remain unknown, and further researches are needed to clarify whether the NO reduction affects to the GTP-Rac1 or GTP-RhoA degradation observed in C-ion irradiated MIAPaCa-2.

Citation Format: Mayumi Fujita, Kaori Imadome, Yoshimi Shoji, Robert Cheng, Aparna H. Kesarwala, David A. Wink, Takashi Imai. Role of nitric oxide in invasiveness of tumor cells irradiated with carbon-ion beams. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4140. doi:10.1158/1538-7445.AM2015-4140