The Myc-dependent angiogenic switch in tumors is mediated by interleukin 1beta

Perspective on the dynamics of cancer

BACKGROUND

The genetic diversity of cancer and the dynamic interactions between heterogeneous tumor cells, the stroma and immune cells present daunting challenges to the development of effective cancer therapies. Although cancer biology is more understood than ever, this has not translated into therapies that overcome drug resistance, cancer recurrence and metastasis. The future development of effective therapies will require more understanding of the dynamics of homeostatic dysregulation that drives cancer growth and progression.

RESULTS

Cancer dynamics are explored using a model involving genes mediating the regulatory interactions between the signaling and metabolic pathways. The exploration is informed by a proposed genetic dysregulation measure of cellular processes. The analysis of the interaction dynamics between cancer cells, cancer associated fibroblasts, and tumor associate macrophages suggests that the mutual dependence of these cells promotes cancer growth and proliferation. In particular, MTOR and AMPK are hypothesized to be concurrently activated in cancer cells by amino acids recycled from the stroma. This leads to a proliferative growth supported by an upregulated glycolysis and a tricarboxylic acid cycle driven by glutamine sourced from the stroma. In other words, while genetic aberrations ignite carcinogenesis and lead to the dysregulation of key cellular processes, it is postulated that the dysregulation of metabolism locks cancer cells in a state of mutual dependence with the tumor microenvironment and deepens the tumor's inflammation and immunosuppressive state which perpetuates as a result the growth and proliferation dynamics of cancer.

CONCLUSIONS

Cancer therapies should aim for a progressive disruption of the dynamics of interactions between cancer cells and the tumor microenvironment by targeting metabolic dysregulation and inflammation to partially restore tissue homeostasis and turn on the immune cancer kill switch. One potentially effective cancer therapeutic strategy is to induce the reduction of lactate and steer the tumor microenvironment to a state of reduced inflammation so as to enable an effective intervention of the immune system. The translation of this therapeutic approach into treatment regimens would however require more understanding of the adaptive complexity of cancer resulting from the interactions of cancer cells with the tumor microenvironment and the immune system.

Fibroblasts accelerate islet revascularization and improve long-term graft survival in a mouse model of subcutaneous islet transplantation

Pancreatic islet transplantation has been considered for many years a promising therapy for beta-cell replacement in patients with type-1 diabetes despite that long-term clinical results are not as satisfactory. This fact points to the necessity of designing strategies to improve and accelerate islets engraftment, paying special attention to events assuring their revascularization. Fibroblasts constitute a cell population that collaborates on tissue homeostasis, keeping the equilibrium between production and degradation of structural components as well as maintaining the required amount of survival factors. Our group has developed a model for subcutaneous islet transplantation using a plasma-based scaffold containing fibroblasts as accessory cells that allowed achieving glycemic control in diabetic mice. Transplanted tissue engraftment is critical during the first days after transplantation, thus we have gone in depth into the graft-supporting role of fibroblasts during the first ten days after islet transplantation. All mice transplanted with islets embedded in the plasma-based scaffold reversed hyperglycemia, although long-term glycemic control was maintained only in the group transplanted with the fibroblasts-containing scaffold. By gene expression analysis and histology examination during the first days we could conclude that these differences might be explained by overexpression of genes involved in vessel development as well as in β-cell regeneration that were detected when fibroblasts were present in the graft. Furthermore, fibroblasts presence correlated with a faster graft re-vascularization, a higher insulin-positive area and a lower cell death. Therefore, this work underlines the importance of fibroblasts as accessory cells in islet transplantation, and suggests its possible use in other graft-supporting strategies.

Modeling and Targeting MYC Genes in Childhood Brain Tumors

Brain tumors are the second most common group of childhood cancers, accounting for about 20%–25% of all pediatric tumors. Deregulated expression of the MYC family of transcription factors, particularly c-MYC and MYCN genes, has been found in many of these neoplasms, and their expression levels are often correlated with poor prognosis. Elevated c-MYC/MYCN initiates and drives tumorigenesis in many in vivo model systems of pediatric brain tumors. Therefore, inhibition of their oncogenic function is an attractive therapeutic target. In this review, we explore the roles of MYC oncoproteins and their molecular targets during the formation, maintenance, and recurrence of childhood brain tumors. We also briefly summarize recent progress in the development of therapeutic approaches for pharmacological inhibition of MYC activity in these tumors.

Myeloid-Derived Suppressor Cells and Proinflammatory Cytokines as Targets for Cancer Therapy

Myeloid-derived suppressor cells represent a heterogeneous population of immature myeloid cells. Under normal conditions, these cells differentiate into macrophages, dendritic cells, and granulocytes. However, in pathological states such as inflammation, infection, or tumor growth, there is an arrest of their differentiation that results in the accumulation of immature myeloid cells in the organism. In addition, these cells acquire a suppressor phenotype, expressing anti-inflammatory cytokines and reactive oxygen and nitrogen species, and suppress T-cell immune response. Myeloid-derived suppressor cells (MDSC) contribute to cancerogenesis by forming a favorable microenvironment for tumor growth. Proinflammatory cytokines, secreted by tumor cells and the tumor microenvironment, induce angiogenesis and metastasis and promote tumor growth. They also provide signals necessary for survival, accumulation, and function of MDSC. Understanding the mechanisms of myeloid suppressor cell development and the use of proinflammatory cytokine inhibitors may prove beneficial for tumor therapy.

Nucleolin Targeting Impairs the Progression of Pancreatic Cancer and Promotes the Normalization of Tumor Vasculature

Pancreatic cancer is a highly aggressive tumor, mostly resistant to the standard treatments. Nucleolin is overexpressed in cancers and its inhibition impairs tumor growth. Herein, we showed that nucleolin was overexpressed in human specimens of pancreatic ductal adenocarcinoma (PDAC) and that the overall survival significantly increased in patients with low levels of nucleolin. The nucleolin antagonist N6L strongly impaired the growth of primary tumors and liver metastasis in an orthotopic mouse model of PDAC (mPDAC). Similar antitumor effect of N6L has been observed in a highly angiogenic mouse model of pancreatic neuroendocrine tumor RIP-Tag2. N6L significantly inhibited both human and mouse pancreatic cell proliferation and invasion. Notably, the analysis of tumor vasculature revealed a strong increase of pericyte coverage and vessel perfusion both in mPDAC and RIP-Tag2 tumors, in parallel to an inhibition of tumor hypoxia. Nucleolin inhibition directly affected endothelial cell (EC) activation and changed a proangiogenic signature. Among the vascular activators, nucleolin inhibition significantly decreased angiopoietin-2 (Ang-2) secretion and expression in ECs, in the tumor and in the plasma of mPDAC mice. As a consequence of the observed N6L-induced tumor vessel normalization, pre-treatment with N6L efficiently improved chemotherapeutic drug delivery and increased the antitumor properties of gemcitabine in PDAC mice. In conclusion, nucleolin inhibition is a new anti-pancreatic cancer therapeutic strategy that dually blocks tumor progression and normalizes tumor vasculature, improving the delivery and efficacy of chemotherapeutic drugs. Moreover, we unveiled Ang-2 as a potential target and suitable response biomarker for N6L treatment in pancreatic cancer. Cancer Res; 76(24); 7181-93. ©2016 AACR.

Concerted Action of PGC-1-related Coactivator (PRC) and c-MYC in the Stress Response to Mitochondrial Dysfunction

PGC-1-related coactivator (PRC) has a dual function in growth-regulated mitochondrial biogenesis and as a sensor of metabolic stress. PRC induction by mitochondrial inhibitors, intracellular ROS, or topoisomerase I inhibition orchestrates an inflammatory program associated with the adaptation to cellular stress. Activation of this program is accompanied by the coordinate expression of c-MYC, which is linked kinetically to that of PRC in response to multiple stress inducers. Here, we show that the c-MYC inhibitor 10058-F4 blocks the induction of c-MYC, PRC, and representative PRC-dependent stress genes by the respiratory chain uncoupler, carbonyl cyanide m-chlorophenyl hydrazine (CCCP). This result, confirmed by the suppression of PRC induction by c-MYC siRNA silencing, demonstrates a requirement for c-MYC in orchestrating the stress program. PRC steady-state expression was markedly increased upon mutation of two GSK-3 serine phosphorylation sites within the carboxyl-terminal domain. The negative control of PRC expression by GSK-3 was consistent with the phosphor-inactivation of GSK-3β by CCCP and by the induction of PRC by the GSK-3 inhibitor AZD2858. Unlike PRC, which was induced post-translationally through increased protein half-life, c-MYC was induced predominantly at the mRNA level. Moreover, suppression of Akt activation by the Akt inhibitor MK-2206 blocked the CCCP induction of PRC, c-MYC, and representative PRC stress genes, demonstrating a requirement for Akt signaling. MK-2206 also inhibited the phosphor-inactivation of GSK-3β by CCCP, a result consistent with the ability of Akt to phosphorylate, and thereby suppress GSK-3 activity. Thus, PRC and c-MYC can act in concert through Akt-GSK-3 signaling to reprogram gene expression in response to mitochondrial stress.

Chemokines, cytokines and exosomes help tumors to shape inflammatory microenvironment

Relationship between inflammation and cancer is now well-established and represents a paradigm that our immune response does not necessarily serves solely to protect us from infections and cancer. Many specific mechanisms that link chronic inflammation to cancer promotion and metastasis have been uncovered in the recent years. Here we are focusing on the effects that tumors may exert on inflammatory cascades, tuning the immune system ability to cause tumor promotion or regression. In particular, we discuss the contributions of chemokines, cytokines and exosomes to the processes such as induction of inflammation and tumorigenesis. Overall, tumor-elicited inflammation is a key driver of tumor progression and an essential component of tumor microenvironment.

Macrophages, Inflammation, and Lung Cancer

Lung cancer is the leading cause of cancer mortality worldwide, and at only 18%, it has one of the lowest 5-year survival rates of all malignancies. With its highly complex mutational landscape, treatment strategies against lung cancer have proved largely ineffective. However with the recent success of immunotherapy trials in lung cancer, there is renewed enthusiasm in targeting the immune component of tumors. Macrophages make up the majority of the immune infiltrate in tumors and are a key cell type linking inflammation and cancer. Although the mechanisms through which inflammation promotes cancer are not fully understood, two connected hypotheses have emerged: an intrinsic pathway, driven by genetic alterations that lead to neoplasia and inflammation, and an extrinsic pathway, driven by inflammatory conditions that increase cancer risk. Here, we discuss the contribution of macrophages to these pathways and subsequently their roles in established tumors. We highlight studies investigating the association of macrophages with lung cancer prognosis and discuss emerging therapeutic strategies for targeting macrophages in the tumor microenvironment.

Monocytes promote liver carcinogenesis in an oncogene-specific manner

BACKGROUND & AIMS

The leukocyte composition of tumors is heterogeneous, as is the involvement of each leukocyte subset in promoting or restraining tumorigenesis. This heterogeneity reflects the tissue of origin, tumor stage, and the functional state of leukocyte activation, but its biological roots remain poorly understood. Since tumorigenesis is driven by various genetic events, we assessed the role of driver genes in shaping the profiles and the roles of leukocytes in tumorigenesis.

METHODS

Mouse liver tumors were induced by hepatic overexpression of either MYC or the combination of myristoylated AKT and NRAS(V12) oncogenes via hydrodynamic transfection. A comparative, flow cytometry- and histology-based immunophenotyping of liver-infiltrating leukocytes was performed at various stages of liver tumorigenesis. The roles of the most abundant leukocyte subsets in tumorigenesis were addressed by immunodepletion. The contribution of liver injury was assessed by comparing the injury-inducing hydrodynamic transfection model to a model in which MYC is an inducible transgene.

RESULTS

Myristoylated AKT and NRAS(V12) promoted a marked recruitment of CD11b(+)Ly6G(hi)Ly6C(int) neutrophils and CD11b(+)Ly6G(-)Ly6C(hi) monocytes to the liver, but their immunodepletion did not alter tumorigenesis. In contrast, despite minimal invasion by monocytes/neutrophils during MYC-driven tumorigenesis, immunodepletion of these cells reduced MYC tumor burden and extended survival. MYC-driven tumor initiation was augmented specifically by Ly6C+ monocytes and their ability to promote liver injury.

CONCLUSIONS

Our results demonstrate that leukocyte profiles do not necessarily predict their involvement in tumorigenesis, the functional role of leukocytes can be shaped by oncogenes, and that monocyte-dependent tissue injury selectively cooperates with MYC during tumorigenesis.

The progress of angiogenic factors in the development of leukemias

Angiogenic factors have been demonstrated to play important roles in modulating angiogenesis of solid tumors. Recently, accumulating studies extensively indicated that some angiogenic factors widely exist in malignant cells of hematologic malignancy, which regulated the expression of a number of genes that were involved in abnormal proliferation, differentiation and apoptosis of these cells. With deep research of angiogenic factors, its expression, function and regulatory mechanism were gradually elucidated, and some of them were related to the development and prognosis of leukemia, or provide more possible strategies for treatment of patients with leukemia. Herein, we summarize the progress in study of some important angiogenic factors and hematological malignancies.

Immunogenic, cellular, and angiogenic drivers of tumor dormancy--a melanoma view

In tumor cells, the ability to maintain viability over long time periods without proliferation is referred to as a state of dormancy. Maintenance of dormancy is controlled by numerous cellular and environmental factors, from immune surveillance and tumor-stroma interaction to intracellular signaling. Interference of dormancy (to an 'awaken' state) is associated with reduced response to therapy, resulting in relapse or in metastatic burst. Thus, maintaining a dormant state should prolong therapeutic responses and delay metastasis. Technical obstacles in studying tumor dormancy have limited our understanding of underlying mechanisms and hampered our ability to target dormant cells. In this review, we summarize the progress of research in the field of immunogenic, angiogenic, and cellular dormancy in diverse malignancies with particular attention to our current understanding in melanoma.

Interactions between Myc and Mediators of Inflammation in Chronic Liver Diseases

Most chronic liver diseases (CLDs) are characterized by inflammatory processes with aberrant expressions of various pro- and anti-inflammatory mediators in the liver. These mediators are the driving force of many inflammatory liver disorders, which often result in fibrosis, cirrhosis, and liver tumorigenesis. c-Myc is involved in many cellular events such as cell growth, proliferation, and differentiation. c-Myc upregulates IL-8, IL-10, TNF-α, and TGF-β, while IL-1, IL-2, IL-4, TNF-α, and TGF-β promote c-Myc expression. Their interactions play a central role in fibrosis, cirrhosis, and liver cancer. Molecular interference of their interactions offers possible therapeutic potential for CLDs. In this review, current knowledge of the molecular interactions between c-Myc and various well known inflammatory mediators is discussed.

Inflammation and skeletal metastasis

On the road to metastasis a cancer cell has to overcome two major obstacles: the physical escape from the primary tumor to a distant tissue and the adaptation to the new microenvironment via colonization and the formation of a secondary tumor. Accumulated scientific findings support the hypothesis that inflammation is a critical component of the tumor microenvironment and develops as a result of tumor-induced recruitment of inflammatory cells and their reciprocal interaction with other cells from the tumor network. These interactions modulate immune responses to suppress antitumor immunity and activate feedback amplification signaling loops that link nearly all the cells in the cancer inflammatory milieu. The coordinated regulation of cytokines/chemokines, receptors and other inflammatory mediators enables the different steps of the metastatic cascade. As a target organ for colonization, the bone is rich in inflammatory mediators that are critical for successful cancer growth. In this review, we focus on the inflammatory cells, molecules and mechanisms that facilitate the expansion of cancer cells from the primary tumor to their new 'home' in the skeleton.

Cancer microenvironment, inflammation and cancer stem cells: A hypothesis for a paradigm change and new targets in cancer control

Since President Nixon officially declared a war on cancer with the National Cancer Act, billions of dollars have been spent on research in hopes of finding a cure for cancer. Recent reviews have pointed out that over the ensuing 42 years, cancer death rates have barely changed for the major cancers. Recently, several researchers have questioned the prevailing cancer paradigm based on recent discoveries concerning the mechanism of carcinogenesis and the origins of cancer. Over the past decade we have learned a great deal concerning both of these central issues. Cell signaling has taken center stage, particularly as regards the links between chronic inflammation and cancer development. It is now evident that the common factor among a great number of carcinogenic agents is activation of genes controlling inflammation cell-signaling pathways and that these signals control all aspects of the cancer process. Of these pathways, the most important and common to all cancers is the NFκB and STAT3 pathways. The second discovery of critical importance is that mutated stem cells appear to be in charge of the cancer process. Most chemotherapy agents and radiotherapy kill daughter cells of the cancer stem cell, many of which are not tumorigenic themselves. Most cancer stem cells are completely resistant to conventional treatments, which explain dormancy and the poor cure rate with metastatic tumors. A growing number of studies are finding that several polyphenol extracts can kill cancer stem cells as well as daughter cells and can enhance the effectiveness and safety of conventional treatments. These new discoveries provide the clinician with a whole new set of targets for cancer control and cure.

Deficiency for the cysteine protease cathepsin L impairs Myc-induced tumorigenesis in a mouse model of pancreatic neuroendocrine cancer

Motivated by the recent implication of cysteine protease cathepsin L as a potential target for anti-cancer drug development, we used a conditional MycERTAM;Bcl-xL model of pancreatic neuroendocrine tumorigenesis (PNET) to assess the role of cathepsin L in Myc-induced tumor progression. By employing a cysteine cathepsin activity probe in vivo and in vitro, we first established that cathepsin activity increases during the initial stages of MycERTAM;Bcl-xL tumor development. Among the cathepsin family members investigated, only cathepsin L was predominately produced by beta-tumor cells in neoplastic pancreata and, consistent with this, cathepsin L mRNA expression was rapidly upregulated following Myc activation in the beta cell compartment. By contrast, cathepsins B, S and C were highly enriched in tumor-infiltrating leukocytes. Genetic deletion of cathepsin L had no discernible effect on the initiation of neoplastic growth or concordant angiogenesis. However, the tumors that developed in the cathepsin L-deficient background were markedly reduced in size relative to their typical wild-type counterparts, indicative of a role for cathepsin L in enabling expansive tumor growth. Thus, genetic blockade of cathepsin L activity is inferred to retard Myc-driven tumor growth, encouraging the potential utility of pharmacological inhibitors of cysteine cathepsins in treating late stage tumors.

What can rheumatologists learn from translational cancer therapy?

It is well established that an intimate connection exists between inflammation and neoplasia. Indeed, particular chronic infections and autoimmune processes giving rise to prolonged site-specific inflammation are known to increase the probability of the development of specific cancers. Molecular characterisation of these processes has revealed profound similarities in the specific molecules involved in persistence of inflammation and in both the primary induction of neoplastic processes and in specification of the preferred anatomic sites of metastatic spread. The therapeutic importance of these findings is underscored by the remarkable success in the treatment of autoimmune pathology using medications initially developed for use in oncology and this arena is one of considerable therapeutic promise for rheumatologists.

Distinct mechanisms of induction of hepatic growth hormone resistance by endogenous IL-6, TNF-α, and IL-1β

During inflammation, the liver becomes resistant to growth hormone (GH) actions, leading to downregulation of the GH target gene IGF-I and activation of catabolism. Proinflammatory cytokines IL-6, TNF-α, and IL-1β are critically involved in the pathogenesis of hepatic GH resistance. However, the mechanisms used by endogenous IL-6, TNF-α, and IL-1β to inhibit the hepatic GH-IGF-I pathway during inflammation are not fully understood. Here, we show that TNF-α and IL-1β inhibited GH receptor (GHR) expression but had minor effects on the downstream suppressor of cytokine signaling (SOCS)3, while IL-6 induced SOCS3 expression but had no effect on GHR expression in Huh-7 cells. Consistent with the in vitro observations, neutralization of TNF-α and IL-1β in mouse models of inflammation did not significantly alter SOCS3 expression stimulated by inflammation but restored GHR and IGF-I expression suppressed by inflammation. Neutralization of IL-6 did not alter inflammation-suppressed GHR expression but drastically reduced the inflammation-stimulated SOCS3 expression and restored IGF-I expression. Interestingly, when the GH-IGF-I pathway was turned off by maximal inhibition of GHR expression, IL-6 and SOCS3 were no longer able to regulate IGF-I expression. Taken together, our results suggest that TNF-α/IL-1β and IL-6 use distinct mechanisms to induce hepatic GH resistance, with TNF-α and IL-1β acting primarily on GHR and IL-6 acting primarily on SOCS3. IL-6 action may be superseded by factors such as TNF-α and IL-1β that inhibit GHR expression.

The role IL-1 in tumor-mediated angiogenesis

Tumor angiogenesis is one of the hallmarks of tumor progression and is essential for invasiveness and metastasis. Myeloid inflammatory cells, such as immature myeloid precursor cells, also termed myeloid-derived suppressor cells (MDSCs), neutrophils, and monocytes/macrophages, are recruited to the tumor microenvironment by factors released by the malignant cells that are subsequently “educated” in situ to acquire a pro-invasive, pro-angiogenic, and immunosuppressive phenotype. The proximity of myeloid cells to endothelial cells (ECs) lining blood vessels suggests that they play an important role in the angiogenic response, possibly by secreting a network of cytokines/chemokines and inflammatory mediators, as well as via activation of ECs for proliferation and secretion of pro-angiogenic factors. Interleukin-1 (IL-1) is an “alarm,” upstream, pro-inflammatory cytokine that is generated primarily by myeloid cells. IL-1 initiates and propagates inflammation, mainly by inducing a local cytokine network and enhancing inflammatory cell infiltration to affected sites and by augmenting adhesion molecule expression on ECs and leukocytes. Pro-inflammatory mediators were recently shown to play an important role in tumor-mediated angiogenesis and blocking their function may suppress tumor progression. In this review, we summarize the interactions between IL-1 and other pro-angiogenic factors during normal and pathological conditions. In addition, the feasibility of IL-1 neutralization approaches for anti-cancer therapy is discussed.

Small-molecule inhibitors of the Myc oncoprotein

The c-Myc (Myc) oncoprotein is among the most attractive of cancer targets given that it is de-regulated in the majority of tumors and that its inhibition profoundly affects their growth and/or survival. However, its role as a seldom-mutated transcription factor, its lack of enzymatic activity for which suitable pharmaceutical inhibitors could be crafted and its expression by normal cells have largely been responsible for its being viewed as "undruggable". Work over the past several years, however, has begun to reverse this idea by allowing us to view Myc within the larger context of global gene regulatory control. Thus, Myc and its obligate heterodimeric partner, Max, are integral to the coordinated recruitment and post-translational modification of components of the core transcriptional machinery. Moreover, Myc over-expression re-programs numerous critical cellular functions and alters the cell's susceptibility to their inhibition. This new knowledge has therefore served as a framework upon which to develop new pharmaceutical approaches. These include the continuing development of small molecules which act directly to inhibit the critical Myc-Max interaction, those which act indirectly to prevent Myc-directed post-translational modifications necessary to initiate productive transcription and those which inhibit vital pathways upon which the Myc-transformed cell is particularly reliant. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.

Mammalian MYC Proteins and Cancer

The MYC family of proteins is a group of basic-helix-loop-helix-leucine zipper transcription factors that feature prominently in cancer. Overexpression of MYC is observed in the vast majority of human malignancies and promotes an extraordinary set of changes that impact cell proliferation, growth, metabolism, DNA replication, cell cycle progression, cell adhesion, differentiation, and metastasis. The purpose of this review is to introduce the reader to the mammalian family of MYC proteins, highlight important functional properties that endow them with their potent oncogenic potential, describe their mechanisms of action and of deregulation in cancer cells, and discuss efforts to target the unique properties of MYC, and of MYC-driven tumors, to treat cancer.

Critical role for IL-1β in DNA damage-induced mucositis

β-TrCP, the substrate recognition subunit of SCF-type ubiquitin ligases, is ubiquitously expressed from two distinct paralogs, targeting for degradation many regulatory proteins, among which is the NF-κB inhibitor IκB. To appreciate tissue-specific roles of β-TrCP, we studied the consequences of inducible ablation of three or all four alleles of the E3 in the mouse gut. The ablation resulted in mucositis, a destructive gut mucosal inflammation, which is a common complication of different cancer therapies and represents a major obstacle to successful chemoradiation therapy. We identified epithelial-derived IL-1β as the culprit of mucositis onset, inducing mucosal barrier breach. Surprisingly, epithelial IL-1β is induced by DNA damage via an NF-κB-independent mechanism. Tissue damage caused by gut barrier disruption is exacerbated in the absence of NF-κB, with failure to express the endogenous IL-1β receptor antagonist IL-1Ra upon four-allele loss. Antibody neutralization of IL-1β prevents epithelial tight junction dysfunction and alleviates mucositis in β-TrCP-deficient mice. IL-1β antagonists should thus be considered for prevention and treatment of severe morbidity associated with mucositis.

Comprehensive genetic analysis of early host body reactions to the bioactive and bio-inert porous scaffolds

To design scaffolds for tissue regeneration, details of the host body reaction to the scaffolds must be studied. Host body reactions have been investigated mainly by immunohistological observations for a long time. Despite of recent dramatic development in genetic analysis technologies, genetically comprehensive changes in host body reactions are hardly studied. There is no information about host body reactions that can predict successful tissue regeneration in the future. In the present study, porous polyethylene scaffolds were coated with bioactive collagen or bio-inert poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB) and were implanted subcutaneously and compared the host body reaction to those substrates by normalizing the result using control non-coat polyethylene scaffold. The comprehensive analyses of early host body reactions to the scaffolds were carried out using a DNA microarray assay. Within numerous genes which were expressed differently among these scaffolds, particular genes related to inflammation, wound healing, and angiogenesis were focused upon. Interleukin (IL)-1β and IL-10 are important cytokines in tissue responses to biomaterials because IL-1β promotes both inflammation and wound healing and IL-10 suppresses both of them. IL-1β was up-regulated in the collagen-coated scaffold. Collagen-specifically up-regulated genes contained both M1- and M2-macrophage-related genes. Marked vessel formation in the collagen-coated scaffold was occurred in accordance with the up-regulation of many angiogenesis-inducible factors. The DNA microarray assay provided global information regarding the host body reaction. Interestingly, several up-regulated genes were detected even on the very bio-inert PMB-coated surfaces and those genes include inflammation-suppressive and wound healing-suppressive IL-10, suggesting that not only active tissue response but also the inert response may relates to these genetic regulations.

IL-32 promotes angiogenesis

IL-32 is a multifaceted cytokine with a role in infections, autoimmune diseases, and cancer, and it exerts diverse functions, including aggravation of inflammation and inhibition of virus propagation. We previously identified IL-32 as a critical regulator of endothelial cell (EC) functions, and we now reveal that IL-32 also possesses angiogenic properties. The hyperproliferative ECs of human pulmonary arterial hypertension and glioblastoma multiforme exhibited a markedly increased abundance of IL-32, and, significantly, the cytokine colocalized with integrin αVβ3. Vascular endothelial growth factor (VEGF) receptor blockade, which resulted in EC hyperproliferation, increased IL-32 three-fold. Small interfering RNA-mediated silencing of IL-32 negated the 58% proliferation of ECs that occurred within 24 h in scrambled-transfected controls. Reduction of IL-32 neither affected apoptosis (insignificant changes in Bak-1, Bcl-2, Bcl-xL, lactate dehydrogenase, annexin V, and propidium iodide) nor VEGF or TGF-β levels, but siIL-32-transfected adult and neonatal ECs produced up to 61% less NO, IL-8, and matrix metalloproteinase-9, and up to 3-fold more activin A and endostatin. In coculture-based angiogenesis assays, IL-32γ dose-dependently increased tube formation up to 3-fold; an αVβ3 inhibitor prevented this activity and reduced IL-32γ-induced IL-8 by 85%. In matrigel plugs loaded with IL-32γ, VEGF, or vehicle and injected into live mice, we observed the anticipated VEGF-induced increase in neocapillarization (8-fold versus vehicle), but unexpectedly, IL-32γ was equally angiogenic. A second signal such as IFN-γ was required to render cells responsive to exogenous IL-32γ; importantly, this was confirmed using a completely synthetic preparation of IL-32γ. In summary, we add angiogenic properties that are mediated by integrin αVβ3 but VEGF-independent to the portfolio of IL-32, implicating a role for this versatile cytokine in pulmonary arterial hypertension and neoplastic diseases.

The evolution of the cancer niche during multistage carcinogenesis

The concept of the tumour microenvironment recognizes that the interplay between cancer cells and stromal cells is a crucial determinant of cancer growth. In this Perspectives article, we propose the novel concept that the tumour microenvironment is built through rate-limiting steps during multistage carcinogenesis. Construction of a 'precancer niche' is a necessary and early step that is required for initiated cells to survive and evolve; subsequent niche expansion and maturation accompany tumour promotion and progression, respectively. As such, cancer niches represent an emergent property of a tumour that could be a robust target for cancer prevention and therapy.

The structural network of inflammation and cancer: merits and challenges

Inflammation, the first line of defense against pathogens can contribute to all phases of tumorigenesis, including tumor initiation, promotion and metastasis. Within this framework, the Toll-like receptor (TLR) pathway plays a central role in inflammation and cancer. Although extremely useful, the classical representation of this, and other pathways in the cellular network in terms of nodes (proteins) and edges (interactions) is incomplete. Structural pathways can help complete missing parts of such diagrams: they demonstrate in detail how signals coming from different upstream pathways merge and propagate downstream, how parallel pathways compensate each other in drug resistant mutants, how multi-subunit signaling complexes form and in particular why they are needed and how they work, how allosteric events can control these proteins and their pathways, and intricate details of feedback loops and how kick in. They can also explain the mechanisms of some oncogenic SNP mutations. Constructing structural pathways is a challenging task. Here, our goal is to provide an overview of inflammation and cancer from the structural standpoint, focusing on the TLR pathway. We use the powerful PRISM (PRotein Interactions by Structural Matching) tool to reveal important structural information of interactions in and within key orchestrators of the TLR pathway, such as MyD88.

Noncanonical roles of the immune system in eliciting oncogene addiction

Cancer is highly complex. The magnitude of this complexity makes it highly surprising that even the brief suppression of an oncogene can sometimes result in rapid and sustained tumor regression, illustrating that cancers can be 'oncogene addicted' [1-10]. The essential implication is that oncogenes may not only fuel the initiation of tumorigenesis, but in some cases must be excessively activated to maintain a neoplastic state [11]. Oncogene suppression acutely restores normal physiological programs that effectively overrides secondary genetic events and a cancer collapses [12,13]. Oncogene addiction is the description of the dramatic and sustained regression of some cancers upon the specific inactivation of a single oncogene [1-13,14(••),15,16(••)], that can occur through tumor intrinsic [1,2,4,12], but also host immune mechanisms [17-23]. Notably, oncogene inactivation elicits a host immune response that involves specific immune effectors and cytokines that facilitate a remodeling of the tumor microenvironment including the shut down of angiogenesis and the induction of cellular senescence of tumor cells [16(••)]. Hence, immune effectors are not only critically involved in tumor prevention, initiation [17-19], and progression [20], but also appear to be essential to tumor regression upon oncogene inactivation [21,22(••),23(••)]. Understanding how the inactivation of an oncogene elicits a systemic signal in the host that prompts a deconstruction of a tumor could have important implications. The combination of oncogene-targeted therapy together with immunomodulatory therapy may be ideal for the development of both robust tumor intrinsic and immunological responses, effectively leading to sustained tumor regression.

Tumor dormancy, oncogene addiction, cellular senescence, and self-renewal programs

Cancers are frequently addicted to initiating oncogenes that elicit aberrant cellular proliferation, self-renewal, and apoptosis. Restoration of oncogenes to normal physiologic regulation can elicit dramatic reversal of the neoplastic phenotype, including reduced proliferation and increased apoptosis of tumor cells (Science 297(5578):63-64, 2002). In some cases, oncogene inactivation is associated with compete elimination of a tumor. However, in other cases, oncogene inactivation induces a conversion of tumor cells to a dormant state that is associated with cellular differentiation and/or loss of the ability to self-replicate. Importantly, this dormant state is reversible, with tumor cells regaining the ability to self-renew upon oncogene reactivation. Thus, understanding the mechanism of oncogene inactivation-induced dormancy may be crucial for predicting therapeutic outcome of targeted therapy. One important mechanistic insight into tumor dormancy is that oncogene addiction might involve regulation of a decision between self-renewal and cellular senescence. Recent evidence suggests that this decision is regulated by multiple mechanisms that include tumor cell-intrinsic, cell-autonomous mechanisms and host-dependent, tumor cell-non-autonomous programs (Mol Cell 4(2):199-207, 1999; Science 297(5578):102-104, 2002; Nature 431(7012):1112-1117, 2004; Proc Natl Acad Sci U S A 104(32):13028-13033, 2007). In particular, the tumor microenvironment, which is known to be critical during tumor initiation (Cancer Cell 7(5):411-423, 2005; J Clin Invest 121(6):2436-2446, 2011), prevention (Nature 410(6832):1107-1111, 2001), and progression (Cytokine Growth Factor Rev 21(1):3-10, 2010), also appears to dictate when oncogene inactivation elicits the permanent loss of self-renewal through induction of cellular senescence (Nat Rev Clin Oncol 8(3):151-160, 2011; Science 313(5795):1960-1964, 2006; N Engl J Med 351(21):2159-21569, 2004). Thus, oncogene addiction may be best modeled as a consequence of the interplay amongst cell-autonomous and host-dependent programs that define when a therapy will result in tumor dormancy.

Mouse models for studying angiogenesis and lymphangiogenesis in cancer

The formation of new blood vessels (angiogenesis) is required for the growth of most tumors. The tumor microenvironment also induces lymphangiogenic factors that promote metastatic spread. Anti-angiogenic therapy targets the mechanisms behind the growth of the tumor vasculature. During the past two decades, several strategies targeting blood and lymphatic vessels in tumors have been developed. The blocking of vascular endothelial growth factor (VEGF)/VEGF receptor-2 (VEGFR-2) signaling has proven effective for inhibition of tumor angiogenesis and growth, and inhibitors of VEGF-C/VEGFR-3 involved in lymphangiogenesis have recently entered clinical trials. However, thus far anti-angiogenic treatments have been less effective in humans than predicted on the basis of pre-clinical tests in mice. Intrinsic and induced resistance against anti-angiogenesis occurs in patients, and thus far the clinical benefit of the treatments has been limited to modest improvements in overall survival in selected tumor types. Our current knowledge of tumor angiogenesis is based mainly on experiments performed in tumor-transplanted mice, and it has become evident that these models are not representative of human cancer. For an improved understanding, angiogenesis research needs models that better recapitulate the multistep tumorigenesis of human cancers, from the initial genetic insults in single cells to malignant progression in a proper tissue environment. To improve anti-angiogenic therapies in cancer patients, it is necessary to identify additional molecular targets important for tumor angiogenesis, and to get mechanistic insight into their interactions for eventual combinatorial targeting. The recent development of techniques for manipulating the mammalian genome in a precise and predictable manner has opened up new possibilities for the generation of more reliable models of human cancer that are essential for the testing of new therapeutic strategies. In addition, new imaging modalities that permit visualization of the entire mouse tumor vasculature down to the resolution of single capillaries have been developed in pre-clinical models and will likely benefit clinical imaging.

The role of IL-1β in the early tumor cell-induced angiogenic response

In this study, we assessed the involvement of IL-1β in early angiogenic responses induced by malignant cells using Matrigel plugs supplemented with B16 melanoma cells. We found that during the angiogenic response, IL-1β and vascular endothelial growth factor (VEGF) interact in a newly described autoinduction circuit, in which each of these cytokines induces the other. The IL-1β and VEGF circuit acts through interactions between bone marrow-derived VEGF receptor 1(+)/IL-1R1(+) immature myeloid cells and tissue endothelial cells. Myeloid cells produce IL-1β and additional proinflammatory cytokines, which subsequently activate endothelial cells to produce VEGF and other proangiogenic factors and provide the inflammatory microenvironment for angiogenesis and tumor progression. These mechanisms were also observed in a nontumor early angiogenic response elicited in Matrigel plugs by either rIL-1β or recombinant VEGF. We have shown that IL-1β inhibition stably reduces tumor growth by limiting inflammation and inducing the maturation of immature myeloid cells into M1 macrophages. In sharp contrast, only transient inhibition of tumor growth was observed after VEGF neutralization, followed by tumor recurrence mediated by rebound angiogenesis. This occurs via the reprogramming of VEGF receptor 1(+)/IL-1R1(+) cells to express hypoxia inducible factor-1α, VEGF, and other angiogenic factors, thereby directly supporting proliferation of endothelial cells and blood vessel formation in a paracrine manner. We suggest using IL-1β inhibition as an effective antitumor therapy and are currently optimizing the conditions for its application in the clinic.

Reduction of splenic immunosuppressive cells and enhancement of anti-tumor immunity by synergy of fish oil and selenium yeast

Growing evidence has shown that regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) abnormally increase in cancer cachectic patients. Suppressions of Tregs and MDSCs may enhance anti-tumor immunity for cancer patients. Fish oil and selenium have been known to have many biological activities such as anti-inflammation and anti-oxidation. Whether fish oil and/or selenium have an additional effect on population of immunosuppressive cells in tumor-bearing hosts remained elusive and controversial. To gain insights into their roles on anti-tumor immunity, we studied the fish oil- and/or selenium-mediated tumor suppression and immunity on lung carcinoma, whereof cachexia develops. Advancement of cachexia in a murine lung cancer model manifested with such indicative symptoms as weight loss, chronic inflammation and disturbed immune functionality. The elevation of Tregs and MDSCs in spleens of tumor-bearing mice was positively correlated with tumor burdens. Consumption of either fish oil or selenium had little or no effect on the levels of Tregs and MDSCs. However, consumption of both fish oil and selenium together presented a synergistic effect-The population of Tregs and MDSCs decreased as opposed to increase of anti-tumor immunity when both fish oil and selenium were supplemented simultaneously, whereby losses of body weight and muscle/fat mass were alleviated significantly.

Role of epigenetics in inflammation-associated diseases

There is considerable evidence suggesting that epigenetic mechanisms may mediate development of chronic inflammation by modulating the expression of pro-inflammatory cytokine TNF-α, interleukins, tumor suppressor genes, oncogenes and autocrine and paracrine activation of the transcription factor NF-κB. These molecules are constitutively produced by a variety of cells under chronic inflammatory conditions, which in turn leads to the development of major diseases such as autoimmune disorders, chronic obstructive pulmonary diseases, neurodegenerative diseases and cancer. Distinct or global changes in the epigenetic landscape are hallmarks of chronic inflammation driven diseases. Epigenetics include changes to distinct markers on the genome and associated cellular transcriptional machinery that are copied during cell division (mitosis and meiosis). These changes appear for a short span of time and they necessarily do not make permanent changes to the primary DNA sequence itself. However, the most frequently observed epigenetic changes include aberrant DNA methylation, and histone acetylation and deacetylation. In this chapter, we focus on pro-inflammatory molecules that are regulated by enzymes involved in epigenetic modifications such as arginine and lysine methyl transferases, DNA methyltransferase, histone acetyltransferases and histone deacetylases and their role in inflammation driven diseases. Agents that modulate or inhibit these epigenetic modifications, such as HAT or HDAC inhibitors have shown great potential in inhibiting the progression of these diseases. Given the plasticity of these epigenetic changes and their readiness to respond to intervention by small molecule inhibitors, there is a tremendous potential for the development of novel therapeutics that will serve as direct or adjuvant therapeutic compounds in the treatment of these diseases.

Finding cancer's weakest link

The biological programs of vertebrates exhibit a remarkable degree of functional degeneracy, adaptive compensation and robustness, to preserve homeostasis and generate reproducible phenotypic outputs irrespective of variations in signal strength, noise and quality. Cancers are difficult to treat not only because they are so mechanistically diverse but also because they adapt or evolve in response to any pharmacological elective pressure we impose upon them. Hence, an ideal cancer drug target would exert a function both necessary for cancer cell survival and functionally non-redundant, rendering it impossible for tumor cells to compensate for, or evolve independence from, the inhibitory effect of any drug aimed at that target. In this review, we discuss the unique, non-degenerate and highly pleiotropic role played by Myc in coordinating, engaging and maintaining the diverse intracellular and extracellular programs required for cell proliferation in vivo. These properties make Myc a compelling candidate cancer drug target, at least in principle: an assertion recently reinforced by new in vivo genetic data.

MYC on the path to cancer

The MYC oncogene contributes to the genesis of many human cancers. Recent insights into its expression and function have led to therapeutic opportunities. MYC's activation by bromodomain proteins could be inhibited by drug-like molecules, resulting in tumor inhibition in vivo. Tumor growth can also be curbed by pharmacologically uncoupling bioenergetic pathways involving glucose or glutamine metabolism from Myc-induced cellular biomass accumulation. Other approaches to halt Myc on the path to cancer involve targeting Myc-Max dimerization or Myc-induced microRNA expression. Here the richness of our understanding of MYC is reviewed, highlighting new biological insights and opportunities for cancer therapies.

Modeling pharmacological inhibition of mast cell degranulation as a therapy for insulinoma

Myc, a pleiotropic transcription factor that is deregulated and/or overexpressed in most human cancers, instructs multiple extracellular programs that are required to sustain the complex microenvironment needed for tumor maintenance, including remodeling of tumor stroma, angiogenesis, and inflammation. We previously showed in a model of pancreatic β-cell tumorigenesis that acute Myc activation in vivo triggers rapid recruitment of mast cells to the tumor site and that this is absolutely required for angiogenesis and macroscopic tumor expansion. Moreover, systemic inhibition of mast cell degranulation with sodium cromoglycate induced death of tumor and endothelial cells in established tumors. Hence, mast cells are required both to establish and to maintain the tumors. Whereas this intimates that selective inhibition of mast cell function could be therapeutically efficacious, cromoglycate is not a practical drug for systemic delivery in humans, and no other systemic inhibitor of mast cell degranulation has hitherto been available. PCI-32765 is a novel inhibitor of Bruton tyrosine kinase (Btk) that blocks mast cell degranulation and is currently in clinical trial as a therapy for B-cell non-Hodgkin lymphoma. Here, we show that systemic treatment of insulinoma-bearing mice with PCI-32765 efficiently inhibits Btk, blocks mast cell degranulation, and triggers collapse of tumor vasculature and tumor regression. These data reinforce the notion that mast cell function is required for maintenance of certain tumor types and indicate that the Btk inhibitor PCI-32765 may be useful in treating such diseases.

Increased invasiveness of MMP-9-deficient tumors in two mouse models of neuroendocrine tumorigenesis

Despite their apparent success in pre-clinical trials, metalloproteinase (MMP) inhibitors proved to be inefficacious in clinical settings. In an effort to understand the underlying causes of this unanticipated outcome, we modeled the consequences of long-term MMP inhibition by removing one of the major players in tumorigenesis, MMP9, in two complimentary mouse models of pancreatic neuroendocrine carcinogenesis: Myc;BclXl and RIP1-Tag2. By employing gel zymography and a fluoregenic solution assay, we first established that MMP9 is expressed and activated in Myc;BclXl tumors in an interleukin-1β-dependent manner. The genetic deletion of MMP9 in Myc;BclXl mice impairs tumor angiogenesis and growth analogous to its absence in the RIP1-Tag2 model. Notably, tumors that developed in the context of MMP9-deficient backgrounds in both models were markedly more invasive than their typical wild-type counterparts, and expressed elevated levels of pro-invasive cysteine cathepsin B. The increased invasion of MMP9-deficient tumors was associated with a switch in the spectrum of inflammatory cells at the tumor margins, involving homing of previously undetected, cathepsin-B expressing CD11b;Gr1-positive cells to the invasive fronts. Thus, plasticity in the tumor inflammatory compartment is partially responsible for changes in the expression pattern of tumor-associated proteases, and may contribute to the compensatory effects observed on MMP inhibition, hence accounting for the heightened tumor progression described in late stage clinical trials.

Multifaceted link between cancer and inflammation

Increasing evidence from epidemiological, preclinical and clinical studies suggests that dysregulated inflammatory response plays a pivotal role in a multitude of chronic ailments including cancer. The molecular mechanism(s) by which chronic inflammation drives cancer initiation and promotion include increased production of pro-inflammatory mediators, such as cytokines, chemokines, reactive oxygen intermediates, increased expression of oncogenes, COX-2 (cyclo-oxygenase-2), 5-LOX (5-lipoxygenase) and MMPs (matrix metalloproteinases), and pro-inflammatory transcription factors such as NF-κB (nuclear factor κB), STAT3 (signal transducer and activator of transcription 3), AP-1 (activator protein 1) and HIF-1α (hypoxia-inducible factor 1α) that mediate tumour cell proliferation, transformation, metastasis, survival, invasion, angiogenesis, chemoresistance and radioresistance. These inflammation-associated molecules are activated by a number of environmental and lifestyle-related factors including infectious agents, tobacco, stress, diet, obesity and alcohol, which together are thought to drive as much as 90% of all cancers. The present review will focus primarily on the role of various inflammatory intermediates responsible for tumour initiation and progression, and discuss in detail the critical link between inflammation and cancer.

Differentiation and gene expression profile of tumor-associated macrophages

Tumor microenvironment is composed of proliferating neoplastic cells, a vascular network of endothelial cells, extra cellular matrix produced by fibroblasts, cellular compartments of adaptive immunity like lymphocytes and dendritic cells as well as cells of innate immunity, e.g., natural killer cells and macrophages. Many pre-clinical and clinical studies demonstrate an inversed correlation between macrophage infiltrate and patients' prognosis indicating a macrophage supporting role for tumor progression as producers of growth and angiogenic factors and as regulators of tissue remodelling. Based on in vitro models, macrophages have been classified in pro-inflammatory, classically activated macrophages (M1; stimulated by IFN-γ or LPS) and anti-inflammatory, alternatively activated macrophages (M2; stimulated by either IL-4/IL-13, IL-1β/LPS in combination with immune complexes or by IL-10/TGFβ/glucocorticoids). Tumor escape has been linked with a switch from M1 activation in the early tumor initiation process towards M2-like phenotype during tumor progression, a process that highlights the heterogeneity and plasticity of macrophage activation and which offers a possible therapeutic target directed against reversing the TAM phenotype in the tumor. Here, we review different tumor-environmental stimuli and signalling cascades involved in this switch in differentiation and the so connected gene regulation in TAMs. In addition, therapeutic applications deducted from this differentiation and gene regulatory processes are presented. Data from pre-clinical as well as clinical studies clearly support the notion, that TAMs are excellent novel therapeutic targets for the fight against cancer.

Production of IL1-beta by ovarian cancer cells induces mesothelial cell beta1-integrin expression facilitating peritoneal dissemination

Background

A crucial step in the metastatic spread of ovarian cancer (OC) is the adhesion and implantation of tumor cells to the peritoneal mesothelium. In order to study this step in the cascade, we derived a pro-metastatic human ovarian carcinoma cell line (MFOC3) from the non-metastatic FOC3 line.

Methods

Molecular profiling of the isogeneic lines identified differentially expressed genes, and investigation for a role in dissemination for specific factors was achieved by development of a co-culture adhesion assay utilizing monolayers of human mesothelial cells.

Results

After murine intraperitoneal inoculation, the FOC3 cell line formed no metastases, but the MFOC3 subline formed metastases in > 80% of SCID mice. MFOC3 cells also adhered 2-3 times more avidly to mesothelial monolayers. This adhesion was inhibited by neutralizing antibodies to IL-1β and enhanced by recombinant IL-1β (p < 0.01). IL-1β induced mesothelial cell β1-integrin, and an antibody to this subunit also inhibited the adhesion of MFOC3 to mesothelial cells in vitro and significantly reduced metastases in vivo. Immunohistochemical analysis of a cohort of 96 ovarian cancer cases showed that negative IL-1β expression was significantly associated with an improved overall survival rate.

Conclusions

These results suggest that a IL-1β/β1-integrin axis plays a role in ovarian tumor cell adhesion to mesothelia, a crucial step in ovarian cancer dissemination.

Immunology in the clinic review series; focus on cancer: multiple roles for the immune system in oncogene addiction

Despite complex genomic and epigenetic abnormalities, many cancers are irrevocably dependent on an initiating oncogenic lesion whose restoration to a normal physiological activation can elicit a dramatic and sudden reversal of their neoplastic properties. This phenomenon of the reversal of tumorigenesis has been described as oncogene addiction. Oncogene addiction had been thought to occur largely through tumour cell-autonomous mechanisms such as proliferative arrest, apoptosis, differentiation and cellular senescence. However, the immune system plays an integral role in almost every aspect of tumorigenesis, including tumour initiation, prevention and progression as well as the response to therapeutics. Here we highlight more recent evidence suggesting that oncogene addiction may be integrally dependent upon host immune-mediated mechanisms, including specific immune effectors and cytokines that regulate tumour cell senescence and tumour-associated angiogenesis. Hence, the host immune system is essential to oncogene addiction.

Chronic inflammation in cancer development

Chronic inflammatory mediators exert pleiotropic effects in the development of cancer. On the one hand, inflammation favors carcinogenesis, malignant transformation, tumor growth, invasion, and metastatic spread; on the other hand inflammation can stimulate immune effector mechanisms that might limit tumor growth. The link between cancer and inflammation depends on intrinsic and extrinsic pathways. Both pathways result in the activation of transcription factors such as NF-κB, STAT-3, and HIF-1 and in accumulation of tumorigenic factors in tumor and microenvironment. STAT-3 and NF-κB interact at multiple levels and thereby boost tumor-associated inflammation which can suppress anti-tumor immune responses. These factors also promote tumor growth, progression, and metastatic spread. IL-1, IL-6, TNF, and PGHS-2 are key mediators of an inflammatory milieu by modulating the expression of tumor-promoting factors. In this review we concentrate on the crucial role of pro-inflammatory mediators in inflammation-driven carcinogenesis and outline molecular mechanisms of IL-1 signaling in tumors. In addition, we elucidate the dual roles of stress proteins as danger signals in the development of anti-cancer immunity and anti-apoptotic functions.

Cancer and inflammation: an old intuition with rapidly evolving new concepts

Recent scientific advances have contributed much to the dissection of the complex molecular and cellular pathways involved in the connection between cancer and inflammation. The evidence for this connection in humans is based on the association between infection or chronic sterile inflammation and cancer. The decreased incidence of tumors in individuals who have used nonsteroidal anti-inflammatory drugs is supportive of a role for inflammation in cancer susceptibility. The increased incidence of tumors in overweight patients points to a role for adipose tissue inflammation and energy metabolism in cancer. Energy metabolism, obesity, and genetic instability are regulated in part by the relationship of the organism with commensal bacteria that affect inflammation with both local and systemic effects. Different aspects of inflammation appear to regulate all phases of malignant disease, including susceptibility, initiation, progression, dissemination, morbidity, and mortality.

Myc posttranscriptionally induces HIF1 protein and target gene expression in normal and cancer cells

c-Myc is frequently overexpressed in tumors and plays an important role in the regulation of cancer metabolism. Hypoxia-inducible factor-1 (HIF1), the master regulator of the hypoxic response, enhances tumorigenesis and influences metabolism via upregulation of the glycolytic pathway and suppression of mitochondrial respiration. Together, deregulated Myc and HIF1 cooperate to lend metabolic advantages to proliferating cancer cells and contribute to the Warburg effect. Here we show that overexpression of Myc significantly stabilizes the α subunit of HIF1 (HIF1α) under normoxic conditions and enhances HIF1α accumulation under hypoxic conditions in cells. Posttranscriptional regulation of HIF1α by Myc led to the induction of HIF1α gene targets. Normoxic HIF1α protein expression was also dependent on Myc. Functionally, HIF1α expression was required for Myc-induced anchorage-independent growth and cell proliferation. Myc-dependent stabilization of HIF1α involved either disruption of binding to the VHL complex or posttranslational protein modifications. Taken together, our findings uncover a previously uncharacterized regulatory relationship between Myc and HIF1 that has important implications for cancer metabolism and development.

MYC and Breast Cancer

MYC is a key regulator of cell growth, proliferation, metabolism, differentiation, and apoptosis. MYC deregulation contributes to breast cancer development and progression and is associated with poor outcomes. Multiple mechanisms are involved in MYC deregulation in breast cancer, including gene amplification, transcriptional regulation, and mRNA and protein stabilization, which correlate with loss of tumor suppressors and activation of oncogenic pathways. The heterogeneity in breast cancer is increasingly recognized. Breast cancer has been classified into 5 or more subtypes based on gene expression profiles, and each subtype has distinct biological features and clinical outcomes. Among these subtypes, basal-like tumor is associated with a poor prognosis and has a lack of therapeutic targets. MYC is overexpressed in the basal-like subtype and may serve as a target for this aggressive subtype of breast cancer. Tumor suppressor BRCA1 inhibits MYC's transcriptional and transforming activity. Loss of BRCA1 with MYC overexpression leads to the development of breast cancer-especially, basal-like breast cancer. As a downstream effector of estrogen receptor and epidermal growth factor receptor family pathways, MYC may contribute to resistance to adjuvant therapy. Targeting MYC-regulated pathways in combination with inhibitors of other oncogenic pathways may provide a promising therapeutic strategy for breast cancer, the basal-like subtype in particular.

Tumor microenvironment: becoming sick of Myc

Several years ago, we described Myc as "the oncogene from hell", since evidence had just emerged that Myc, aside from being responsible for cell-cycle progression and tumor expansion, was also able to induce genomic instability in culture, wreaking havoc in tumor cells and accelerating tumor progression (Soucek and Evan, Cancer Cell 1:406-408, 2002; Vafa et al., Mol Cell 9:1031-1044, 2002). In this review, we discuss recent publications that expand Myc's evil armory to include coordination of the crosstalk between tumor and microenvironment. Indeed, endogenous Myc, acting as a client for upstream oncogenic lesions, instructs the tumor stroma, engages a complex inflammatory response and induces angiogenesis, thus allowing the tumor to thrive. This is highly topical in light of the fact that Hanahan and Weinberg have recently redefined the hallmarks of cancer and pointed out that genomic instability and inflammation are essential for both their acquisition and development (Hanahan and Weinberg, Cell 144:646-674, 2011). Myc, it seems, is behind it all.

Inhibitors of Glioma Growth that Reveal the Tumour to the Immune System

Treated glioblastoma patients survive from 6 to 14 months. In the first part of this review, we describe glioma origins, cancer stem cells and the genomic alterations that generate dysregulated cell division, with enhanced proliferation and diverse response to radiation and chemotherapy. We review the pathways that mediate tumour cell proliferation, neo-angiogenesis, tumor cell invasion, as well as necrotic and apoptotic cell death. Then, we examine the ability of gliomas to evade and suppress the host immune system, exhibited at the levels of antigen recognition and immune activation, limiting the effective signaling between glioma and host immune cells.The second part of the review presents current therapies and their drawbacks. This is followed by a summary of the work of our laboratory during the past 20 years, on oligosaccharide and glycosphingolipid inhibitors of astroblast and astrocytoma division. Neurostatins, the O-acetylated forms of gangliosides GD1b and GT1b naturally present in mammalian brain, are cytostatic for normal astroblasts, but cytotoxic for rat C6 glioma cells and human astrocytoma grades III and IV, with ID50 values ranging from 200 to 450 nM. The inhibitors do not affect neurons or fibroblasts up to concentrations of 4 μM or higher.At least four different neurostatin-activated, cell-mediated antitumoral processes, lead to tumor destruction: (i) inhibition of tumor neovascularization; (ii) activation of microglia; (iii) activation of natural killer (NK) cells; (iv) activation of cytotoxic lymphocytes (CTL). The enhanced antigenicity of neurostatin-treated glioma cells, could be related to their increased expression of connexin 43. Because neurostatins and their analogues show specific activity and no toxicity for normal cells, a clinical trial would be the logical next step.

EGCG downregulates IL-1RI expression and suppresses IL-1-induced tumorigenic factors in human pancreatic adenocarcinoma cells

Human pancreatic cancer is currently one of the fifth-leading causes of cancer-related mortality with a 5-year survival rate of less than 5%. Since pancreatic carcinoma is largely refractory to conventional therapies, there is a strong medical need for the development of novel and innovative therapeutic strategies. Increasing evidence suggests an association of carcinogenesis and chronic inflammation. Because IL-1 plays a crucial role in inflammation-associated carcinogenesis, we analyzed the biological effects of IL-1 and its modulation by the chemopreventive green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) in the human pancreatic adenocarcinoma cell line Colo357. Proinflammatory IL-6 and PGHS-2 as well as proangiogenic IL-8 and VEGF were induced by IL-1, whereas the secretion of invasion-promoting MMP-2 remained unaffected. IL-1 responsiveness and constitutive MMP-2 release in Colo357 were downregulated by EGCG in a dose- and time-dependent manner. Moreover, EGCG reduced cell viability via induction of apoptosis in Colo357. Since EGCG effects on cytokine production precede reduction in cell viability, we hypothesize that these findings are not only a result of cell death but also depend on alterations in the IL-1 signaling cascade. In this context, we found for the first time an EGCG-induced downregulation of the IL-1RI expression possibly being caused by NF-κB inhibition and causative for its inhibitory action on the production of tumorigenic factors. Thus, our data might have future clinical implications with respect to the development of novel approaches as an adjuvant therapy in high-risk patients with human pancreatic carcinoma.