Molecular pathways: toll-like receptors in the tumor microenvironment--poor prognosis or new therapeutic opportunity

Toll like receptor signaling pathway as a potential therapeutic target in colorectal cancer

Toll like receptor (TLR) signaling is involved in activating innate and adaptive immune responses and plays a critical role in inflammation-induced diseases such as colorectal cancer (CRC). Dysregulation of this signaling pathway can result in disturbance of epithelial layer hemostasis, chronic inflammatory, excessive repair responses, and development of CRC. There is now substantial evidence for the benefit of targeting of this pathway in cancer treatment, and several agents have been approved, such as BCG (Bacillus Calmette Guérin), MPL (monophosphoryl lipid A) and imiquimod. This review summarizes the current knowledge about the different functions of TLRs on tumor cells and their application in cancer therapy with particular emphasis on recent preclinical and clinical research in treatment of CRC.

TLR3 expression status predicts prognosis in patients with advanced thoracic esophageal squamous cell carcinoma after esophagectomy

BACKGROUND

The relationship between Toll-like receptors (TLRs) and esophageal squamous cell carcinoma (ESCC) is not completely understood.

METHODS

RT-qPCR was used to evaluate the mRNA expression of TLR1-10 in 13 ESCC lines. We then used ESCC tissue microarray (TMA) to confirm expression of TLR3 protein in patients with ESCC.

RESULTS

All ESCC lines showed 10-60 times higher TLR3 mRNA expression than PBLs. High expression of TLR3 correlated with favorable 5-year overall survival (OS) and disease specific survival (DSS) among patients with ESCC after esophagectomy (p < 0.01). Additionally, In the adjuvant chemotherapy group, TLR3 high patients had significantly better 5-year OS compared to TLR3 low patients (60.2%, 34.4%, respectively) but not in the surgery alone group.

CONCLUSION

High TLR3 expression is an independent prognostic factor and has the potential to serve as a clinically useful marker of the need for adjuvant chemotherapy after esophagectomy in patients with advanced thoracic ESCC.

Complement anaphylatoxins C3a and C5a: Emerging roles in cancer progression and treatment

Recent insights into the role of complement anaphylatoxins C3a and C5a in cancer provide new opportunities for the development of innovative biomarkers and therapeutic strategies. These two complement activation products can maintain chronic inflammation, promote an immunosuppressive microenvironment, induce angiogenesis, and increase the motility and metastatic potential of cancer cells. Still, the diverse heterogeneity of responses mediated by these peptides poses a challenge both to our understanding of the role played by these molecules in cancer progression and to the development of effective treatments. This review attempts to summarize the evidence surrounding the involvement of anaphylatoxins in the biological contexts associated with tumor progression. We also describe the recent developments that support the inhibition of anaphylatoxins, or their cognate receptors C3aR and C5aR1, as a treatment option for maximizing the clinical efficacy of current immunotherapies that target the PD-1/PD-L1 immune checkpoint.

Intravesical Immunomodulatory Imiquimod Enhances Bacillus Calmette-Guérin Downregulation of Nonmuscle-invasive Bladder Cancer

BACKGROUND

The Toll-like receptor (TLR)2/4 agonist bacillus Calmette-Guérin (BCG), although not failure proof, has been the most efficient immunomodulatory treatment of immunogenic nonmuscle-invasive bladder cancer (NMIBC) for > 40 years. We investigated the role of the immunomodulatory molecule TLR7 agonist imiquimod through the BCG key receptors TLR2/4 and the main downstream molecules of the mammalian target of rapamycin pathway in NMIBC treatment.

MATERIALS AND METHODS

A total of 40 Fischer-344 rats, 7 weeks old, received 4 doses of 1.5 mg/kg N-methyl-N-nitrosourea intravesically on weeks 0, 2, 4, and 6 for cancer induction. At week 8, the rats were randomized into 4 groups (10 per group) and treated intravesically once a week for 6 weeks: control (0.2 mL of vehicle); BCG (2 × 10⁶ colony-forming units Connaught strain in 0.2 mL); imiquimod (20 mg/kg in 0.2 mL), and associated treatment BCG plus imiquimod in 0.2 mL. The bladders were extracted and analyzed for histopathology, immunohistochemistry, cell proliferation (Ki-67), apoptosis (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling [TUNEL]), and immunoblotting for TLR2, TLR4, p-P70S6K, and p-4E-BP1 proteins.

RESULTS

The histopathology results showed that BCG and imiquimod decreased bladder tumorigenesis compared with the control group, with a proliferation decrease (Ki-67) and an apoptosis increase (TUNEL). BCG upregulated TLR2/4, imiquimod upregulated TLR4, and both downregulated P70S6K1.

CONCLUSION

Imiquimod is able to efficiently decrease bladder carcinogenesis through upregulation of TLR7/4 and downregulation of P70S6K1 protein, generating new perspectives to boost BCG effects in the future.

Immunology Comes Full Circle in Melanoma While Specific Immunity Is Unleashed to Eliminate Metastatic Disease, Inflammatory Products of Innate Immunity Promote Resistance

Melanoma and many other cancers often express cells and molecular features of inflammation. Intrinsic to melanoma is the expression of a continuous cycle of cytokines and oxidative stress markers. The oxidative stress of inflammation is proposed to drive a metastatic process, not only of DNA adducts and crosslinks, but also of posttranslational oxidative modifications to lipids and proteins that we argue support growth and survival. Fortunately, numerous antioxidant agents are available clinically and we further propose that the pharmacological attenuation of these inflammatory processes, particularly the reactive nitrogen species, will restore the cancer cells to an apoptosis-permissive and growth-inhibitory state. Experimental model data using a small-molecule arginine antagonist that prevents enzymatic production of nitric oxide supports this view directly. I propose that the recognition, measurement, and regulation of such carcinogenic inflammation be considered as part of the approach to the treatment of cancer.

Characterizing the Association Between Toll-like Receptor Subtypes and Nephrolithiasis With Renal Inflammation in an Animal Model

OBJECTIVE

To show experimentally induced renal stone disease and to evaluate secondary inflammatory responses in vivo, and to characterize changes in the expression of Toll-like receptor (TLR) subtypes in this model.

METHODS

Twenty 5- to 6-week-old male Wistar rats were divided into control and hyperoxaluria groups (n = 10 per group) and were supplied with normal water or 1% ethylene glycol, respectively, for 16 weeks. The animals were then placed in metabolic cages, and urine was collected for a 24-hour urine oxalate level evaluation. Following sacrifice, rats were subjected to bilateral nephrectomy and both kidneys were histopathologically evaluated. A 1-mm³ biopsy section from the right kidney of each rat was subjected to real-time polymerase chain reaction of the TLR expression.

RESULTS

At the end of week 16, the hyperoxaluria group had a higher mean 24-hour urine oxalate level (1.91) than the control group (0.29) (P <.05) and a remarkably increased deposition of renal CaOx crystals (15/20) than the control group (0/20) (P <.05), which was universally accompanied by inflammation (15/15). Twelve and no rats in the hyperoxaluria and control groups, respectively, had macroscopically visible renal pelvic stones (P <.05). Quantitative real-time polymerase chain reaction revealed significant decreases in the expression of several TLRs, particularly TLR11 and TLR7. Decreases in TLR1, TLR3, and TLR6 expressions and an increase in the TLR2 expression did not differ significantly between the groups.

CONCLUSION

We believe that is the first evaluation of TLR expression associated with renal stone formation in an animal model of inflammation. These results might lead to novel TLR-based treatments for nephrolithiasis and related inflammatory renal damage.

Inflammatory signaling cascades and autophagy in cancer

Tumor-associated inflammation is predictive of poor prognosis and drives a variety of tumorigenic phenotypes, including tumor proliferation and survival, angiogenesis, invasiveness, and metastasis. Here, we review mammalian data addressing the interaction of macroautophagy/autophagy with key signaling cascades associated with tumor inflammation. Although our understanding of this area remains incomplete, certain inflammatory pathways have emerged as important mediators of the crosstalk between autophagy and inflammation in tumors. Consistent with the multifaceted roles for autophagy in tumor cells, results to date support the hypothesis that inflammatory pathways can suppress or induce autophagy in a context-dependent manner; in turn, autophagy suppresses or promotes inflammation in cancers. Furthermore, emerging data suggest that autophagy may influence cytokine production and secretion via diverse mechanisms, which has implications for the immune and inflammatory microenvironment in tumors.

Toll-Like Receptor 7 Staining in Malignant Epithelial Tumors

BACKGROUND

As important players of the innate immune system, Toll-like receptors (TLRs) and their role for tumorigenesis have been in the focus of research. In particular TLR7 is an interesting candidate, as TLR7 agonists are broadly used for the treatment of cutaneous tumors. However, data addressing the baseline expression of TLR7 in both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) on the protein level are lacking, while on the genomic level significantly elevated expression of TLR7 in SCC but not in BCC has been demonstrated.

AIM

Our aim was to characterize the immunohistochemical staining pattern of TLR7 in SCC and BCC. Besides, we aimed to clarify if, in case of different TLR7 expression between SCC and BCC, TLR7 expression would help to define basosquamous carcinoma (BSC), a tumor entity sharing characteristics of both SCC and BCC.

METHODS

We examined histopathological samples from 23 BCC, 4 BSC, and 24 SCC and characterized the expression of TLR7 by immunohistochemistry and immunofluorescence.

RESULTS

We found that TLR7 was not expressed by the tumor tissue of SCC, BCC, and BSC, but by inflammatory cells located within the tumoral and/or peritumoral tissue. Whereas the overall expression of TLR7 did not differ between BCC and SCC (30.4% vs. 45.8%, respectively), we found that within the group of SCC, the well-differentiated SCC showed strong tumoral and/or peritumoral immunocellular TLR7 reactivity in contrast to the poorly differentiated SCC (73.33% vs. 11.1%, respectively). Besides, immunofluorescence double staining revealed the expression of TLR7 in immune cells closely interacting with T cells and natural killer cells.

CONCLUSIONS

In contrast to genomic data, we did not find a general difference between baseline TLR7 expression of SCC and BCC on the protein level. Nevertheless, the expression of TLR7 by the inflammatory infiltrate associated with SCC may correlate with the degree of differentiation of SCC possibly indicating better outcome.

Toll-like receptors 7 and 8 expression correlates with the expression of immune biomarkers and positively predicts the clinical outcome of patients with melanoma

Background

Toll-like receptors (TLRs) play a critical role in cancer, yet the clinical relevance of TLR7/8 expression in melanoma remains unclear. This study aimed to evaluate the prognostic value of TLR7/8 mRNA levels in melanoma and their correlation with immune biomarkers relevant to disease progression.

Methods

Normalized gene expression and corresponding clinical data of patients with skin cutaneous melanoma were obtained from two public databases: the Cancer Genome Atlas and GSE19234. Log rank (Mantel–Cox) tests were used to perform survival analysis. Multivariate survival analysis was performed on a Cox-regression hazard model. Spearman correlation analyses were used to address the relationship between the expressions of TLR7/8 levels and immune biomarkers in melanoma tumors.

Results

Survival analysis suggested that high levels of TLR7 or TLR8 expression predicted better clinical outcome for melanoma patients (TLR7: HR =1.734, P<0.0001; TLR8: HR =2.072, P<0.0001). Moreover, multivariate survival analysis implicated TLR7 as a prognostic factor independent of age, gender, or pathological stage. Further analysis demonstrated that expression levels of TLR7/8 strongly correlated with that of dendritic cell markers and chemokines/chemokine receptors, including CCR2, CCR5, CCL3, and CCL5. Importantly, expression levels of both TLR7 and TLR8 were also highly correlated with the expressions of CD8 and other functional markers of CD8⁺ T cells.

Conclusion

High gene expression of TLR7 and TLR8 in melanoma tumors is associated with high expression levels of functional markers of immune cells, which predicts longer overall survival of patients with melanoma. Our results not only provide an important reference for the clinical prognosis of melanoma but also present new implications for the design of melanoma immunotherapy.

Role of Type I and II Interferons in Colorectal Cancer and Melanoma

Cancer can be considered an aberrant organ with a hierarchical composition of different cell populations. The tumor microenvironment, including the immune cells and related cytokines, is crucial during all the steps of tumor development. In particular, type I and II interferons (IFNs) are involved in a plethora of mechanisms that regulate immune responses in cancer, thus balancing immune escape versus immune surveillance. IFNs are involved in both the direct and indirect regulation of cancer cell proliferation and metastatic potential. The mutational background of genes involved in IFNs signaling could serve as a prognostic biomarker and a powerful tool to screen cancer patients eligible for checkpoint blocking therapies. We herewith describe the latest findings regarding the contribution of IFNs in colorectal cancer and melanoma by researching their dual role as either tumor promoter or suppressor, in diverse tumor types, and microenvironmental context. We are reporting the most innovative and promising approaches of IFN-based therapies that have achieved considerable outcomes in clinical oncology practice and explain the possible mechanisms responsible for their failure.

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.

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.

Dual activation of Toll-like receptors 7 and 9 impairs the efficacy of antitumor vaccines in murine models of metastatic breast cancer

PURPOSE

Since combination of Toll-like receptor (TLR) ligands could boost antitumor immunity, we evaluated the efficacy of dendritic cell (DC) vaccines upon dual activation of TLR9 and TLR7 in breast cancer models.

METHODS

DCs were generated from mouse bone marrow or peripheral blood from healthy human donors and stimulated with CpG1826 (mouse TLR9 agonist), CpG2006 or IMT504 (human TLR9 agonists) and R848 (TLR7 agonist). Efficacy of antitumor vaccines was evaluated in BALB/c mice bearing metastatic mammary adenocarcinomas.

RESULTS

CpG-DCs improved the survival of tumor-bearing mice, reduced the development of lung metastases and generated immunological memory. However, dual activation of TLRs impaired the efficacy of DC vaccines. In vitro, we found that R848 inhibited CpG-mediated maturation of murine DCs. A positive feedback loop in TLR9 mRNA expression was observed upon CpG stimulation that was inhibited in the presence of R848. Impaired activation of NF-κB was detected when TLR9 and TLR7 were simultaneously activated. Blockade of nitric oxide synthase (NOS) and indoleamine-pyrrole-2,3-dioxygenase (IDO) improved the activation of CpG-DCs. When we evaluated the effect of combined activation of TLR9 and TLR7 in human DCs, we found that R848 induced robust DC activation that was inhibited by TLR9 agonists.

CONCLUSIONS

These observations provide insight in the biology of TLR9 and TLR7 crosstalk and suggest caution in the selection of agonists for multiple TLR stimulation. Blockade of NOS and IDO could improve the maturation of antitumor DC vaccines. R848 could prove a useful adjuvant for DC vaccines in human patients.

The method for breast cancer grade prediction and pathway analysis based on improved multiple kernel learning

Breast cancer histologic grade represents the morphological assessment of the tumor’s malignancy and aggressiveness, which is vital in clinically planning treatment and estimating prognosis for patients. Therefore, the prediction of breast cancer grade can markedly elevate the detection of early breast cancer and efficiently guide its treatment. With the advent of high-throughput profiling technology, a large number of data of different types are rapidly generated, and each data provides its unique biological insight. Although many researches focused on cancer grade prediction, hardly most of them attempted to integrate multiple data types, by which we cannot only improve and boost results obtained from learning method, but also have a good understanding or explanation of biological issues. In this paper, we take advantage of a sophisticated supervised learning method called multiple kernel learning (MKL) to design a breast cancer grading predictor fusing heterogeneous data for classification of breast cancer histopathology. Furthermore, we modify our model by involving biological pathway information. The new model can evaluate the significance of various pathways in which differential expression genes fall between different breast cancer grades. The merits of the novel model are lucubration in bridging between omics data and various phenotypes of breast cancer grades, and providing an auxiliary method integrating omics data of cancer mechanism research. In experiments, the proposed method outperforms other state-of-the-art methods and has abundant biological interpretation in explaining differences between breast cancer grades.

The Unique Molecular and Cellular Microenvironment of Ovarian Cancer

The reciprocal interplay of cancer cells and host cells is an indispensable prerequisite for tumor growth and progression. Cells of both the innate and adaptive immune system, in particular tumor-associated macrophages (TAMs) and T cells, as well as cancer-associated fibroblasts enter into a malicious liaison with tumor cells to create a tumor-promoting and immunosuppressive tumor microenvironment (TME). Ovarian cancer, the most lethal of all gynecological malignancies, is characterized by a unique TME that enables specific and efficient metastatic routes, impairs immune surveillance, and mediates therapy resistance. A characteristic feature of the ovarian cancer TME is the role of resident host cells, in particular activated mesothelial cells, which line the peritoneal cavity in huge numbers, as well as adipocytes of the omentum, the preferred site of metastatic lesions. Another crucial factor is the peritoneal fluid, which enables the transcoelomic spread of tumor cells to other pelvic and peritoneal organs, and occurs at more advanced stages as a malignancy-associated effusion. This ascites is rich in tumor-promoting soluble factors, extracellular vesicles and detached cancer cells as well as large numbers of T cells, TAMs, and other host cells, which cooperate with resident host cells to support tumor progression and immune evasion. In this review, we summarize and discuss our current knowledge of the cellular and molecular interactions that govern this interplay with a focus on signaling networks formed by cytokines, lipids, and extracellular vesicles; the pathophysiologial roles of TAMs and T cells; the mechanism of transcoelomic metastasis; and the cell type selective processing of signals from the TME.

Promising Targets for Cancer Immunotherapy: TLRs, RLRs, and STING-Mediated Innate Immune Pathways

Malignant cancers employ diverse and intricate immune evasion strategies, which lead to inadequately effective responses of many clinical cancer therapies. However, emerging data suggest that activation of the tolerant innate immune system in cancer patients is able, at least partially, to counteract tumor-induced immunosuppression, which indicates triggering of the innate immune response as a novel immunotherapeutic strategy may result in improved therapeutic outcomes for cancer patients. The promising innate immune targets include Toll-like Receptors (TLRs), RIG-I-like Receptors (RLRs), and Stimulator of Interferon Genes (STING). This review discusses the antitumor properties of TLRs, RLRs, and STING-mediated innate immune pathways, as well as the promising innate immune targets for potential application in cancer immunotherapy.

Interplay between Inflammation and Stemness in Cancer Cells: The Role of Toll-Like Receptor Signaling

Cancer stem cells (CSCs) are a small population of cancer cells that exhibit stemness. These cells contribute to cancer metastasis, treatment resistance, and relapse following therapy; therefore, they may cause malignancy and reduce the success of cancer treatment. Nuclear factor kappa B- (NF-κB-) mediated inflammatory responses increase stemness in cancer cells, and CSCs constitutively exhibit higher NF-κB activation, which in turn increases their stemness. These opposite effects form a positive feedback loop that further amplifies inflammation and stemness in cancer cells, thereby expanding CSC populations in the tumor. Toll-like receptors (TLRs) activate NF-κB-mediated inflammatory responses when stimulated by carcinogenic microbes and endogenous molecules released from cells killed during cancer treatment. NF-κB activation by extrinsic TLR ligands increases stemness in cancer cells. Moreover, it was recently shown that increased NF-κB activity and inflammatory responses in CSCs may be caused by altered TLR signaling during the enrichment of stemness in cancer cells. Thus, the activation of TLR signaling by extrinsic and intrinsic factors drives a positive interplay between inflammation and stemness in cancer cells.

Toll Like Receptor 2, 4, and 9 Signaling Promotes Autoregulative Tumor Cell Growth and VEGF/PDGF Expression in Human Pancreatic Cancer

Toll like receptor (TLR) signaling has been suggested to play an important role in the inflammatory microenvironment of solid tumors and through this inflammation-mediated tumor growth. Here, we studied the role of tumor cells in their process of self-maintaining TLR expression independent of inflammatory cells and cytokine milieu for autoregulative tumor growth signaling in pancreatic cancer. We analyzed the expression of TLR2, -4, and -9 in primary human cancers and their impact on tumor growth via induced activation in several established pancreatic cancers. TLR-stimulated pancreatic cancer cells were specifically investigated for activated signaling pathways of VEGF/PDGF and anti-apoptotic Bcl-xL expression as well as tumor cell growth. The primary pancreatic cancers and cell lines expressed TLR2, -4, and -9. TLR-specific stimulation resulted in activated MAP-kinase signaling, most likely via autoregulative stimulation of demonstrated TLR-induced VEGF and PDGF expression. Moreover, TLR activation prompted the expression of Bcl-xL and has been demonstrated for the first time to induce tumor cell proliferation in pancreatic cancer. These findings strongly suggest that pancreatic cancer cells use specific Toll like receptor signaling to promote tumor cell proliferation and emphasize the particular role of TLR2, -4, and -9 in this autoregulative process of tumor cell activation and proliferation in pancreatic cancer.

Human Pancreatic Cancer Cells Induce a MyD88-Dependent Stromal Response to Promote a Tumor-Tolerant Immune Microenvironment

Cancer cells exert mastery over the local tumor-associated stroma (TAS) to configure protective immunity within the tumor microenvironment. The immunomodulatory character of pancreatic lysates of patients with cancer differs from those with pancreatitis. In this study, we evaluated the cross-talk between pancreatic cancer and its TAS in primary human cell culture models. Upon exposure of TAS to pancreatic cancer cell-conditioned media, we documented robust secretion of IL6 and IL8. This TAS response was MyD88-dependent and sufficient to directly suppress both CD4⁺ and CD8⁺ T-cell proliferation, inducing Th17 polarization at the expense of Th1. We found that patients possessed a similar shift in circulating effector memory Th17:Th1 ratios compared with healthy controls. The TAS response also directly suppressed CD8⁺ T-cell-mediated cytotoxicity. Overall, our results demonstrate how TAS contributes to the production of an immunosuppressive tumor microenvironment in pancreatic cancer. Cancer Res; 77(3); 672-83. ©2016 AACR.

Biopathological Significance of TLR9 Expression in Cancer Cells and Tumor Microenvironment Across Invasive Breast Carcinomas Subtypes

Toll-like receptors (TLRs) are pattern recognition receptors mainly expressed by cells of the immune system but also by epithelial tumor cells. Little is known about expression patterns of TLR genes in breast tumors, and their clinical significance is unclear. The aim of our study was to investigate expression of TLRs pathway components in pre-invasive breast lesions and invasive breast carcinomas (IBCs). We used RT-PCR assays to quantify mRNA levels of the 10 TLR genes and genes involved in TLR pathways in 350 breast tumors from patients with known clinical/pathological status and long-term outcome. Sets of 158 breast samples were also analyzed by immunochemistry including; 40 early noninvasive breast lesions, 38 IBCs and 80 triple negative carcinomas subtype (TNCs). We identified TLR9 as the major TLR gene family member upregulated in breast tumors and more particularly in TNCs. Immunohistochemical studies demonstrated that TLR9 protein was expressed in tumor epithelial and stromal cells of the TLR9 mRNA-overexpressing tumors. TLR9 overexpression appears very early during breast carcinogenesis. High TLR9 levels were associated with favorable outcome in the TNC sub-group. TLR9 overexpression was associated with alterations of down-stream components of the TLR9 signaling pathway, epithelio-mesenchymal transition (EMT) induction and EGFR pathway deregulation. TNCs with TLR9 overexpression were significantly correlated with development of a fibrous and inflammatory microenvironment with variable status of nuclear phosphoSTAT3. Our results suggest that TLR9 could play a role in TNC carcinogenesis and could be useful as predictive biomarker and therapeutic target.

Enhanced antimicrobial peptide-induced activity in the mollusc Toll-2 family through evolution via tandem Toll/interleukin-1 receptor

Toll receptors play an important role in the innate immunity of invertebrates. All reported Tolls have only one Toll/interleukin-1 receptor (TIR) domain at the C-terminal. In this study, numerous Tolls with tandem TIRs at the C-terminal were found in molluscs. Such Tolls presented an extra TIR (TIR-1) compared with Toll-I. Thus, Toll-I might be the ancestor of tandem TIRs containing Toll. To test this hypothesis, 83 Toll-I and Toll-2 (most have two TIRs, but others seem to be the evolutionary intermediates) genes from 29 shellfish species were identified. These Tolls were divided into nine groups based on phylogenetic analyses. A strong correlation between phylogeny and motif composition was found. All Toll proteins contained the TIR-2 domain, whereas the TIR-1 domain only existed in some Toll-2 protein, suggesting that TIR-1 domain insertion may play an important role in Toll protein evolution. Further analyses of functional divergence and adaptive evolution showed that some of the critical sites responsible for functional divergence may have been under positive selection. An additional intragenic recombination played an important role in the evolution of the Toll-I and Toll-2 genes. To investigate the functional difference of Toll-I and Toll-2, over expression of Hcu_Toll-I or Hcu_Toll-2-2 in Drosophila S2 cells was performed. Results showed that Hcu_Toll-2-2 had stronger antimicrobial peptide (AMP) activity than Hcu_Toll-I. Therefore, enhanced AMP-induced activity resulted from tandem TIRs in Toll-2s of molluscs during evolution history.

TLR7 Gln11Leu single nucleotide polymorphism and susceptibility to cutaneous melanoma

Cutaneous melanoma is a life-threatening skin cancer. Its incidence is rapidly increasing, and early diagnosis is the main factor able to improve its poor prognosis. Toll-like receptors (TLRs) are transmembrane glycoproteins that recognize pathogen- and damage-associated molecular patterns, against which TLRs activate the innate immune response and initiate the adaptive immune response. Genetic variations of these receptors may alter the immune system, and are involved in evolution and susceptibility to various diseases, including cancer. The aim of the present study was to evaluate whether the presence of TLR7 glutamine (Gln) 11 leucine (Leu) polymorphism confers an increased susceptibility to cutaneous melanoma. For that purpose, a case-control study was performed with 182 melanoma cases and 89 controls. To highlight the possible association between the aforementioned polymorphism and the susceptibility to melanoma, 93 cases of single melanoma and 89 cases of multiple primary melanoma (MPM) were compared in the present study. Since the TLR7 gene is localized on the chromosome X, the allelic frequency of the Gln11Leu polymorphism was analyzed separately in males and females. The distribution of allele frequencies between melanoma cases and controls (P=0.245) and between single melanoma and MPM cases (P=0.482) was not significant. Therefore, the present results do not suggest an association between TLR7 Gln11Leu polymorphism and susceptibility to cutaneous melanoma. Further studies are required to analyze the influence of other TLR polymorphisms on the susceptibility to malignant melanoma and the involvement of innate immunity in this malignancy.

Clinical Significance of TLR1 I602S Polymorphism for Patients with Metastatic Colorectal Cancer Treated with FOLFIRI plus Bevacizumab

The purpose of this study was to evaluate the clinical significance of single-nucleotide polymorphisms in TLR1, TLR2, TLR6, and TAK1 in patients with metastatic colorectal cancer (mCRC). We genotyped 9 SNPs of TLR1, TLR2, TLR6, and TAK1 in mCRC patients treated with first-line FOLFIRI (combination therapy of irinotecan, 5-fluorouracil, and folinic acid) plus bevacizumab, using a discovery cohort (TRIBE trial, n = 228) and a validation cohort (FIRE-3 trial, n = 297), and analyzed for the association with response rate (RR), progression-free survival (PFS), and overall survival (OS). There was a significant association of TLR1 rs5743618 (T1805G) with the clinical outcome. In the TRIBE cohort, a homozygous wild-type genotype (T/T) associated with a significantly lower RR compared with variant T/G and G/G genotypes (43% vs. 62%, P = 0.025), and this observation was validated in the FIRE-3 cohort (46% vs. 65%, P = 0.021). In addition, those patients with the T/T genotype had significantly worse PFS (median, 8.2 vs. 10.5 months; HR, 1.57; 95% CI, 1.09-2.28, P = 0.014) and OS (median: 19.9 vs. 27.9 months; HR, 1.63; 95% CI, 1.14-2.35, P = 0.007), compared with those with other genotypes in the TRIBE cohort. These differences remained statistically significant in multivariate analysis. Our data suggest that TLR1 rs5743618 could serve as a predictor of clinical response to FOLFIRI plus bevacizumab in patients with mCRC. Mol Cancer Ther; 15(7); 1740-5. ©2016 AACR.

Immune responses in multiple myeloma: role of the natural immune surveillance and potential of immunotherapies

Multiple myeloma (MM) is a tumor of terminally differentiated B cells that arises in the bone marrow. Immune interactions appear as key determinants of MM progression. While myeloid cells foster myeloma-promoting inflammation, Natural Killer cells and T lymphocytes mediate protective anti-myeloma responses. The profound immune deregulation occurring in MM patients may be involved in the transition from a premalignant to a malignant stage of the disease. In the last decades, the advent of stem cell transplantation and new therapeutic agents including proteasome inhibitors and immunoregulatory drugs has dramatically improved patient outcomes, suggesting potentially key roles for innate and adaptive immunity in disease control. Nevertheless, MM remains largely incurable for the vast majority of patients. A better understanding of the complex interplay between myeloma cells and their immune environment should pave the way for designing better immunotherapies with the potential of very long term disease control. Here, we review the immunological microenvironment in myeloma. We discuss the role of naturally arising anti-myeloma immune responses and their potential corruption in MM patients. Finally, we detail the numerous promising immune-targeting strategies approved or in clinical trials for the treatment of MM.

Inflammatory microenvironment and human papillomavirus-induced carcinogenesis

More than 15% of the global cancer burden is attributable to infectious agents. Pathogens that cause persistent infections are strongly associated with cancer, inflammation being a major component of the chronic infections as revealed by basic, clinical and epidemiological studies. Persistent infection and viral oncoproteins induce specific cellular pathways modifications that promote tumorigenesis. Deregulated and continuous immune response leads to severe tissue and systemic damage, impaired tumor surveillance and consequent carcinogenesis promotion by selecting for metastatic and therapeutically resistant tumor phenotypes. In this review, the role of inflammatory microenvironment in the HPV-induced carcinogenesis is addressed, with a specific focus on the involvement of the immune molecules and microRNAs as well as their delivery through the microvesicle cargo.

Apigenin-7-O-β-d-glucuronide inhibits LPS-induced inflammation through the inactivation of AP-1 and MAPK signaling pathways in RAW 264.7 macrophages and protects mice against endotoxin shock

In vitro and in vivo anti-inflammatory activities of apigenin-7-O-β-d-glucuronide.

Microbiota modulation of myeloid cells in cancer therapy

Myeloid cells represent a major component of the tumor microenvironment, where they play divergent dual roles. They can induce antitumor immune responses, but mostly they promote immune evasion, tumor progression, and metastasis formation. Thus, strategies aiming at reprogramming the tumor microenvironment represent a promising immunotherapy approach. Myeloid cells respond to environmental factors including signals derived from commensal microbes. In this Cancer Immunology at the Crossroads overview, we discuss recent advances on the effects of the commensal microbiota on myeloid-cell functions and how they affect the response to cancer therapy.

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.

A molecular perspective on rituximab: A monoclonal antibody for B cell non Hodgkin lymphoma and other affections

Rituximab (a chimeric anti-CD20 monoclonal antibody) is the first Food and Drug Administration approved anti-tumor antibody. Immunotherapy by rituximab, especially in combination-therapy, is a mainstay for a vast variety of B-cell malignancies therapy. Its therapeutic value is unquestionable, yet the mechanisms of action responsible for anti-tumor activity of rituximab and rituximab resistance mechanisms are not completely understood. Investigation of the mechanisms of action that contribute to the rituximab activity have eventually directed to a suite of novel combinations and novel treatment schedules, and also have resulted new generations of antibodies with more desired effects. Although, further investigations are needed to define the mechanisms of rituximab resistance and prominent effector activity of the altered next generation anti-CD20 to improve their efficacies and develop new anti-CD20 monoclonal antibodies in NHL treatment. This article focuses on the properties of CD20 which led scientists to select it as an effective therapeutic target and the molecular details of mechanisms of rituximab action and resistance. We also discuss about the impact of rituximab in monotherapy and in combination with chemotherapy regimens. Finally, we comparatively summarize the next generations of anti CD20 monoclonal antibodies to highlight their advantages relative to their ancestor: Rituximab.

Pattern Recognition Receptors in Cancer Progression and Metastasis

The innate immune system is an integral component of the inflammatory response to pathophysiological stimuli. Toll-like receptors (TLRs) and inflammasomes are the major sensors and pattern recognition receptors (PRRs) of the innate immune system that activate stimulus (signal)-specific pro-inflammatory responses. Chronic activation of PRRs has been found to be associated with the aggressiveness of various cancers and poor prognosis. Involvement of PRRs was earlier considered to be limited to infection- and injury-driven carcinogenesis, where they are activated by pathogenic ligands. With the recognition of damage-associated molecular patterns (DAMPs) as ligands of PRRs, the role of PRRs in carcinogenesis has also been implicated in other non-pathogen-driven neoplasms. Dying (apoptotic or necrotic) cells shed a plethora of DAMPs causing persistent activation of PRRs, leading to chronic inflammation and carcinogenesis. Such chronic activation of TLRs promotes tumor cell proliferation and enhances tumor cell invasion and metastasis by regulating pro-inflammatory cytokines, metalloproteinases, and integrins. Due to the decisive role of PRRs in carcinogenesis, targeting PRRs appears to be an effective cancer-preventive strategy. This review provides a brief account on the association of PRRs with various cancers and their role in carcinogenesis.

Toll-like receptors 3, 7, and 9 in Juvenile nasopharyngeal angiofibroma

Juvenile nasopharyngeal angiofibroma (JNA) is a rare, benign tumor affecting adolescent males. The etiology of JNA as well as the causes determining the variable growth patterns of individual tumors remains unknown. Toll-like receptors (TLRs) are part of the innate immune response to microbes; by recognition of distinct features, they link to induction of pro-inflammatory signaling pathways. We immunostained TLR 3, 7, and 9 in 27 JNA specimens of patients treated at the Helsinki University Central Hospital, Helsinki, Finland, during the years 1970-2009.

RESULTS

TLR 3, 7, and 9 expressions were found in stromal and endothelial cells of JNA, and their expression levels varied from negative to very strong positive. TLR 3 expression was found to have a significant correlation with the clinical stage of JNA.

CONCLUSIONS

The present results propose a putative role of TLRs in the growth process of JNA.

n-3 Polyunsaturated Fatty Acids and their Role in Cancer Chemoprevention

Polyunsaturated fatty acids (PUFAs), including omega-3 (n-3) and omega-6 (n-6) PUFAs, are essential for human health. Recent research shows n-3 PUFAs and their mediators can inhibit inflammation, angiogenesis and cancer via multiple mechanisms, including reduced release of n-6 fatty acid arachidonic acid from cell membranes, inhibition of enzymatic activities, and direct competition with arachidonic acid for enzymatic conversions. In this review, we discuss inflammation-related cancer, anti-inflammatory effects of n-3 PUFA lipid mediators, antineoplastic activities of n-3 PUFA in vitro and in vivo, and present an update on recent human trials.

Thymosin α1 promotes the activation of myeloid-derived suppressor cells in a Lewis lung cancer model by upregulating Arginase 1

Thymosin α1 (Tα1) has been tested for cancer therapy for several years, in most cases, the anti-tumor effect of Tα1 was limited, especially when Tα1 was used as a single agent. The role of Tα1 in cancer treatment and the regulatory mechanisms by which Ta1 takes effects are not yet completely understood. Using a Lewis lung caner model, here we report that Tα1 used alone elevated CD8(+) T cells, but failed to inhibit tumor growth. Furthermore, immunosuppressive myeloid-derived suppressor cells (MDSCs) showed heightened Arginase 1 production in response to Tα1 treatment, which led to stronger suppression of anti-tumor immunity. In addition, the upregulation of ARG1 was dependent on TLRs/MyD88 signaling, blocking MyD88 signaling abrogated the enhanced ARG1 expression and restored the anti-tumor efficacy of Tα1. This study provides the first demonstration that Tα1 treatment activates but not expands MDSCs via MyD88 signaling, which indicates better immunotherapeutic strategy of Tα1 against cancer.

TLR3 correlated with cervical lymph node metastasis in patients with papillary thyroid cancer

Papillary thyroid cancer (PTC) is the most rapidly increasing endocrine malignancy worldwide. Although less aggressive than the majority malignancies, PTC exhibits extensive cervical lymph node metastasis in early stage of PTC. However, the underlying molecular mechanism of this early-metastasis remains unknown. Toll like receptors (TLRs) constitute a crucial component of the innate immune response to bacterial and viral pathogens. Emerging evidence suggests that TLRs play important roles in cancer progression, invasion and immune evasion, whereas whether TLRs have any role in PTC remains to be clarified. In this study, we found that TLR3 was present in both PTC specimen and various thyroid cancer cell lines. Further IHC analysis of 63 PTC patients revealed that TLR3 expression was associated with cervical metastasis, but not correlated with patients' TNM staging, extrathyroidal invasion. In addition, TLR3 promoted migration of K1 cells in vitro. Activation of TLR3 increased cancer stem cell marker and migration promoting CD44 expression in vitro, indicating that TLR3 might promote metastasis of PTC via modulating CD44 expression. Taken together, our data revealed that TLR3 is correlated with cervical metastasis of PTC and might be an essential prognostic indicator and target for PTC metastasis.

IFNAR1 is a predictor for overall survival in colorectal cancer and its mRNA expression correlated with IRF7 but not TLR9

Toll-like receptor (TLR) 9 plays a role in intestinal inflammation that, in turn, is related to the tumorigenesis of colorectal cancer. Nuclear factor κB (NFκB), and interferon regulatory factor (IRF) 5 and IRF7 can be activated by TLR9 and induce the production of proinflammatory cytokines and type I interferon, respectively. This study investigated the mRNA expressions of TLR9 and its downstream signaling molecules in both the tumor and the normal tissues of colorectal cancer. Eighty-four subjects with colorectal cancer were consecutively recruited at a community-based hospital, and the mRNA expression of TLR9, NFκB, IRF5, IRF7, interleukin 6 (IL6), and interferon α/β/ω receptor 1 (IFNAR1) in the tumor and normal tissue were determined by real-time reverse transcription polymerase chain reaction using TaqMan FAM-labeled MGB probes (Life Technologies, Carlsbad, CA). The tumor had higher percentages of detection of TLR9, IFNAR1, and IL6 mRNA expressions than normal tissue. The absence of detectable TLR9 mRNA expression was associated with an absence of significance in the correlation between IL6 and NFκB or IRF5, but not that between IRF7 and IFNAR1 in both the tumor and the normal tissues. An absence of detectable IFNAR1 mRNA expression in the tumor (hazard ratio: 3.77; 95% confidence interval: 1.22-11.60) and advanced stage (stages III and IV, 7.86; 1.76-35.40) were significant predictors for overall survival. IFNAR1 is a predictor for overall survival and mRNA expression is correlated to IRF7, but not TLR9 in colorectal cancer. The results cast doubt on the usefulness of TLR9 agonist in treating colorectal cancer.

Intratumoral immunization: a new paradigm for cancer therapy

Immune cell infiltration in the tumor microenvironment is of prognostic and therapeutic import. These immune cell subsets can be heterogeneous and are composed of mature antigen-presenting cells, helper and effector cytotoxic T cells, toleragenic dendritic cells, tumor-associated macrophages, and regulatory T cells, among other cell types. With the development of novel drugs that target the immune system rather than the cancer cells, the tumor immune microenvironment is not only prognostic for overall patient outcome, but also predictive for likelihood of response to these immune-targeted therapies. Such therapies aim to reverse the cancer immunotolerance and trigger an effective antitumor immune response. Two major families of immunostimulatory drugs are currently in clinical development: pattern recognition receptor agonists (PRRago) and immunostimulatory monoclonal antibodies (ISmAb). Despite their immune-targeted design, these agents have so far been developed clinically as if they were typical anticancer drugs. Here, we review the limitations of this conventional approach, specifically addressing the shortcomings of the usual schedules of intravenous infusions every 2 or 3 weeks. If the new modalities of immunotherapy target specific immune cells within the tumor microenvironment, it might be preferable to deliver them locally into the tumor rather than systemically. There is preclinical and clinical evidence that a therapeutic systemic antitumor immune response can be generated upon intratumoral immunomodulation. Moreover, preclinical results have shown that therapeutic synergy can be obtained by combining PRRagos and ISmAbs to the local tumor site.

The role of toll-like receptors in colorectal cancer progression: evidence for epithelial to leucocytic transition

Toll-like receptors (TLRs) are expressed by immune cells, intestinal epithelium, and tumor cells. In the homeostatic setting, they help to regulate control over invading pathogens and maintain the epithelial lining of the large and small intestines. Aberrant expression of certain TLRs by tumor cells can induce growth inhibition while others contribute to tumorigenesis and progression. Activation of these TLRs can induce inflammation, tumor cell proliferation, immune evasion, local invasion, and distant metastasis. These TLR-influenced behaviors have similarities with properties observed in leukocytes, suggesting that tumors may be hijacking immune programs to become more aggressive. The concept of epithelial to leucocytic-transition (ELT) is proposed, akin to epithelial to mesenchymal transition, in which tumors develop the ability to activate leucocytic traits otherwise inaccessible to epithelial cells. Understanding the mechanisms of ELT could lead to novel therapeutic strategies for inhibiting tumor metastasis.

Serum toll-like receptors are potential biomarkers of radiation pneumonia in locally advanced NSCLC

OBJECTIVE

Toll-like receptors (TLRs) are highly or lowly expressed in a wide variety of tumors and exhibit either pro-tumor or anti-tumor activities. In the present study, we investigate whether there are relationships between the expressions of TLRs and the occurrence of radiation pneumonia in advanced NSCLC patients treated with radiotherapy.

MATERIALS AND METHODS

76 patients diagnosed with NSCLC and 50 healthy controls were recruited from Oct 2012 to Jan 2014. The expressions of serum TLR1, TLR2, TLR3, TLR4, TLR5, TLR6, TLR7, TLR8, and TLR9 were detected by ELISA techniques. Fisher exact test, χ(2) test, ROC working curve and Cox regression model were applied to analyze all data.

RESULTS

serum TLR1, TLR2, TLR4, and TLR9 exhibited a relative high expression level in NSCLC patients compared with healthy controls. Importantly, pre-neutrophil granulocyte ratio was associated with the expression of TLR1, TLR2, and TLR4. Moreover, the patients with high ratio of neutrophil granulocyte significantly increased the occurrence of fever in comparison to normal neutrophil ratio in NSCLC patients during the course of radiotherapy. We further evaluated the containing of TLRs when patients had temperatures and found serum TLR1, TLR2 and TLR4 were over-expressed. Finally, 26 of 76 patients were diagnosed with different stages of radiation induced pneumonia; as a result, the contents of TLR1 and TLR4 before radiotherapy were identified as independent significances with pneumonia occurrence.

CONCLUSIONS

The pretreatment levels of TLR1 and TLR4 have the predictive value to be clinically potential biomarkers of pneumonia risk in locally advanced NSCLC.

Toll-like receptors and cancer, particularly oral squamous cell carcinoma

It is becoming increasingly apparent that the tumor microenvironment plays an important role in the progression of cancer. The microenvironment may promote tumor cell survival and proliferation or, alternatively may induce tumor cell apoptosis. Toll-like receptors (TLRs) are transmembrane proteins, expressed on immune cells and epithelial cells, that recognize exogenous and endogenous macromolecules. Once activated, they initiate signaling pathways leading to the release of cytokines and chemokines, which recruit immune cells inducing further cytokine production, the production of angiogenic mediators and growth factors, all of which may influence tumor progression. This paper examines the actions of TLRs in carcinogenesis with particular emphasis on their role in oral squamous cell carcinoma.

Cervical cancer cell supernatants induce a phenotypic switch from U937-derived macrophage-activated M1 state into M2-like suppressor phenotype with change in Toll-like receptor profile

Cervical cancer (CC) is the second most common cancer among women worldwide. Infection with human papillomavirus (HPV) is the main risk factor for developing CC. Macrophages are important immune effector cells; they can be differentiated into two phenotypes, identified as M1 (classically activated) and M2 (alternatively activated). Macrophage polarization exerts profound effects on the Toll-like receptor (TLR) profile. In this study, we evaluated whether the supernatant of human CC cells HeLa, SiHa, and C-33A induces a shift of M1 macrophage toward M2 macrophage in U937-derived macrophages. Results. The results showed that soluble factors secreted by CC cells induce a change in the immunophenotype of macrophages from macrophage M1 into macrophage M2. U937-derived macrophages M1 released proinflammatory cytokines and nitric oxide; however, when these cells were treated with the supernatant of CC cell lines, we observed a turnover of M1 toward M2. These cells increased CD163 and IL-10 expression. The expression of TLR-3, -7, and -9 is increased when the macrophages were treated with the supernatant of CC cells. Conclusions. Our result strongly suggests that CC cells may, through the secretion of soluble factors, induce a change of immunophenotype M1 into M2 macrophages.

Novel Therapies in Development for Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the second most common cause of cancer mortality in the United States. Despite advances in therapy, metastatic CRC remains lethal, and further improvements in therapy are needed. Growing understanding of cancer biology, particularly in growth factor signaling, angiogenesis, and cancer immunology, has translated into many novel therapies under investigation. Patients are increasingly selected for clinical trials rationally on the basis of integral biomarkers. This review discusses several promising agents in development for metastatic CRC.

Gene expression profiles of NO- and HNO-donor treated breast cancer cells: insights into tumor response and resistance pathways

Nitric oxide (NO) synthase 2 (NOS2), a major inflammatory protein, modulates disease progression via NO in a number of pathologies, including cancer. The role of NOS2-derived NO is not only flux-dependent, which is higher in mouse vs human cells, but also varies based on spatial and temporal distribution both within tumor cells and in the tumor microenvironment. NO donors have been utilized to mimic NO flux conditions and to investigate the effects of varied NO concentrations. As a wide range of effects mediated by NO and other nitrogen oxides such as nitroxyl (HNO) have been elucidated, multiple NO- and HNO-releasing compounds have been developed as potential therapeutics, including as tumor modulators. One of the challenges is to determine differences in biomarker expression from extracellular vs intracellular generation of NO or HNO. Taking advantage of new NO and HNO releasing agents, we have characterized the gene expression profile of estrogen receptor-negative human breast cancer (MDA-MB-231) cells following exposure to aspirin, the NO donor DEA/NO, the HNO donor IPA/NO andtheir intracellularly-activated prodrug conjugates DEA/NO-aspirin and IPA/NO-aspirin. Comparison of the gene expression profiles demonstrated that several genes were uniquely expressed with respect to NO or HNO, such as miR-21, HSP70, cystathionine γ-lyase and IL24. These findings provide insight into targets and pathways that could be therapeutically exploited by the redox related species NO and HNO.