Paradoxic effects of metformin on endothelial cells and angiogenesis

We have investigated the effect of metformin on the mechanisms of angiogenesis. We show that metformin, particularly in the context of obesity, inhibits angiogenesis in vivo yet shows a contradictory effect on angiogenesis-related genes and proteins that involve AMPK.

The biguanide metformin is used in type 2 diabetes management and has gained significant attention as a potential cancer preventive agent. Angioprevention represents a mechanism of chemoprevention, yet conflicting data concerning the antiangiogenic action of metformin have emerged. Here, we clarify some of the contradictory effects of metformin on endothelial cells and angiogenesis, using in vitro and in vivo assays combined with transcriptomic and protein array approaches. Metformin inhibits formation of capillary-like networks by endothelial cells; this effect is partially dependent on the energy sensor adenosine-monophosphate-activated protein kinase (AMPK) as shown by small interfering RNA knockdown. Gene expression profiling of human umbilical vein endothelial cells revealed a paradoxical modulation of several angiogenesis-associated genes and proteins by metformin, with short-term induction of vascular endothelial growth factor (VEGF), cyclooxygenase 2 and CXC chemokine receptor 4 at the messenger RNA level and downregulation of ADAMTS1. Antibody array analysis shows an essentially opposite regulation of numerous angiogenesis-associated proteins in endothelial and breast cancer cells including interleukin-8, angiogenin and TIMP-1, as well as selective regulation of angiopioetin-1, -2, endoglin and others. Endothelial cell production of the cytochrome P450 member CYP1B1 is upregulated by tumor cell supernatants in an AMPK-dependent manner, metformin blocks this effect. Metformin inhibits VEGF-dependent activation of extracellular signal-regulated kinase 1/2, and the inhibition of AMPK activity abrogates this event. Metformin hinders angiogenesis in matrigel pellets in vivo, prevents the microvessel density increase observed in obese mice on a high-fat diet, downregulating the number of white adipose tissue endothelial precursor cells. Our data show that metformin has an antiangiogenic activity in vitro and in vivo associated with a contradictory short-term enhancement of pro-angiogenic mediators, as well as with a differential regulation in endothelial and breast cancer cells.

Inflammatory angiogenesis and the tumor microenvironment as targets for cancer therapy and prevention

In addition to aberrant transformed cells, tumors are tissues that contain host components, including stromal cells, vascular cells (ECs) and their precursors, and immune cells. All these constituents interact with each other at the cellular and molecular levels, resulting in the production of an intricate and heterogeneous complex of cells and matrix defined as the tumor microenvironment. Several pathways involved in these interactions have been investigated both in pathological and physiological scenarios, and diverse molecules are currently targets of chemotherapeutic and preventive drugs. Many phytochemicals and their derivatives show the ability to inhibit tumor progression, angiogenesis, and metastasis, exerting effects on the tumor microenvironment. In this review, we will outline the principal players and mechanisms involved in the tumor microenvironment network and we will discuss some interesting compounds aimed at interrupting these interactions and blocking tumor insurgence and progression. The considerations provided will be crucial for the design of new preventive approaches to the reduction in cancer risk that need to be applied to large populations composed of apparently healthy individuals.

Abstract A23: Metformin as a potent antiangiogenic factor: From diabetes to cancer angioprevention

Metformin, an anti-diabetic drug commonly used for type 2 diabetes therapy, is associated with a decreased risk for certain cancer. Due to extensive reports of its in vitro and in vivo anti-tumor activity, we and others have focused on the anti-angiogenic potential as a possible mechanism through which metformin could affect tumor progression, and to propose its use as an angiopreventive drug. Metformin was able to interfere with endothelial cell proliferation, apoptosis and invasion in vitro. Gene arrays analyses were performed to verify the effect of metformin on endothelial gene expression profiles and the matrigel sponge assay to test its effect in vivo.

We show that metformin inhibited endothelial cell proliferation by effecting cell cycle regulation rather than inducing apoptosis. In vitro, metformin reduces endothelial cell invasion and represses their ability to organize into capillary-like networks. These effects are partially reverted by compound C, a specific inhibitor of AMPK, confirming that metformin could interfere with angiogenesis responses by activating AMPK signaling. Gene expression profiles of endothelial cells treated with metformin showed down-regulation of several angiogenesis-related genes but up-regulation of chemokine pathways. In vivo, metformin inhibited angiogenesis induced by VEGF. Considering the strict correlation between type II diabetes and obesity, we evaluated the ability of Metformin to modulate endothelial precursor cells in an obese murine model and we reported that Metformin decreases the number of adipose tissue progenitor endothelial cells in vivo only in obese mice.

These data suggest that metformin has anti-angiogenic effect associated with down-regulation of specific molecule although it also induces some inflammatory mediators, and that it may be most effective in the context of obesity.

Citation Format: Katiuscia Dallaglio, Antonino Bruno, Anna Rita Cantelmo, Ulrich Pfeffer, Francesco Bertolini, Douglas M. Noonan, Adriana Albini. Metformin as a potent antiangiogenic factor: From diabetes to cancer angioprevention. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr A23.

Abstract 2303: Innate immunity driving tumor angiogenesis: the role of natural killer cells in non small cell lung cancer (NSCLC)

Immune cells infiltrating tumors often show a skewed phenotype that reflects attenuation of anti-tumor activity and enhancement of pro-tumor activities, including angiogenesis.

Natural Killer (NK) cells are effectors lymphocytes of innate immunity that can potentially control tumors by their cytotoxic activity. Nevetherless the role of NK cells in angiogenesis remains to be defined.

Here we investigate the subset distribution of tumor infiltrating NKs and the correlation with pro-angiogenic factor production, like VEGF, PlGF and IL-8, on clinical samples belonging from patient with non-small cell lung cancer (NSCLC).

Samples (tumor, adjacent normal tissue and peripheral blood), solid tissues are mechanically dispersed, while blood is processed using a Ficoll gradient. Flow cytometry (FC) analyses were performed to evaluate specific markers (CD56, CD16, CD335, CD3) for NK cells.

The CD56brightCD16−NK phenotype predominated in all NSCLC samples while the CD56dimCD16+ cytotoxic NK phenotype prevailed in adjacent normal tissues and in non-oncologic lung tissues, independent of smoking status. The CD56+CD16− NK subset was associated with angiogenic cytokines production like VEGF, PlGF and IL-8 (CXCL8)

Further, patients with the SQK histotype showed significantly higher angiogenic factor production by CD56+CD16−NK cells infiltrating tumors, adjacent tissues and peripheral blood, compared to those from adenocarcinoma (ADK) and control tissues.

Supernatants derived from NSCLC infiltrating CD56+CD16−NK cells induced endothelial cell chemotaxis and formation of capillary-like structures in vitro, particularly evident in SQK derived NK cell supernatants and absent in controls

As TGFβ1 expression has been associated with poorer survival in non-small cell lung cancer (NSCLC) squamous cell carcinoma (SQK) and polarization of peripheral NK cells towards a decidual NK phenotype, a subset associated with angiogenesis, we evaluated whether TGFb culd be implicated in these polarization phenomena. We demonstrated as exposure to TGFβ1 up-regulated VEGF and PlGF production by peripheral blood CD56+CD16−NK cells from healthy subjects.

Our data suggest that, like other immune cells, NK cells in NSCLC can be switched to an angiogenic phenotype, particularly evident for SQK and likely mediated by TGFβ1, which could contribute to angiogenesis in SQK NSCLC development and progression.

Citation Format: Adriana Albini, Antonino Bruno, Arianna Pagani, Andrea Imperatori, Marco Spagnoletti, Nicola Rotolo, AnnaRita Cantelmo, Francesca Franzi, Carlo Capella, Guido Ferlazzo, Lorenzo Mortara, Douglas M. Noonan. Innate immunity driving tumor angiogenesis: the role of natural killer cells in non small cell lung cancer (NSCLC) . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2303. doi:10.1158/1538-7445.AM2013-2303

Cannabidiol inhibits angiogenesis by multiple mechanisms

BACKGROUND AND PURPOSE

Several studies have demonstrated anti-proliferative and pro-apoptotic actions of cannabinoids on various tumours, together with their anti-angiogenic properties. The non-psychoactive cannabinoid cannabidiol (CBD) effectively inhibits the growth of different types of tumours in vitro and in vivo and down-regulates some pro-angiogenic signals produced by glioma cells. As its anti-angiogenic properties have not been thoroughly investigated to date, and given its very favourable pharmacological and toxicological profile, here, we evaluated the ability of CBD to modulate tumour angiogenesis.

EXPERIMENTAL APPROACH

Firstly, we evaluated the effect of CBD on human umbilical vein endothelial cell (HUVEC) proliferation and viability - through [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and FACS analysis - and in vitro motility - both in a classical Boyden chamber test and in a wound-healing assay. We next investigated CBD effects on different angiogenesis-related proteins released by HUVECs, using an angiogenesis array kit and an ELISA directed at MMP2. Then we evaluated its effects on in vitro angiogenesis in treated HUVECs invading a Matrigel layer and in HUVEC spheroids embedded into collagen gels, and further characterized its effects in vivo using a Matrigel sponge model of angiogenesis in C57/BL6 mice.

KEY RESULTS

CBD induced HUVEC cytostasis without inducing apoptosis, inhibited HUVEC migration, invasion and sprouting in vitro, and angiogenesis in vivo in Matrigel sponges. These effects were associated with the down-modulation of several angiogenesis-related molecules.

CONCLUSIONS AND IMPLICATIONS

This study reveals that CBD inhibits angiogenesis by multiple mechanisms. Its dual effect on both tumour and endothelial cells supports the hypothesis that CBD has potential as an effective agent in cancer therapy.

Cancer prevention by targeting angiogenesis

Healthy individuals can harbour microscopic tumours and dysplastic foci in different organs in an undetectable and asymptomatic state for many years. These lesions do not progress in the absence of angiogenesis or inflammation. Targeting both processes before clinical manifestation can prevent tumour growth and progression. Angioprevention is a chemoprevention approach that interrupts the formation of new blood vessels when tumour cell foci are in an indolent state. Many efficacious chemopreventive drugs function by preventing angiogenesis in the tumour microenvironment. Blocking the vascularization of incipient tumours should maintain a dormancy state such that neoplasia or cancer exist without disease. The current limitations of antiangiogenic cancer therapy may well be related to the use of antiangiogenic agents too late in the disease course. In this Review, we suggest mechanisms and strategies for using antiangiogenesis agents in a safe, preventive clinical angioprevention setting, proposing different levels of clinical angioprevention according to risk, and indicate potential drugs to be employed at these levels. Finally, angioprevention may go well beyond cancer in the prevention of a range of chronic disorders where angiogenesis is crucial, including different forms of inflammatory or autoimmune diseases, ocular disorders, and neurodegeneration.

Surface-activated chemical ionization-electrospray ionization source improves biomarker discovery with mass spectrometry

RATIONALE

Mass spectrometry (MS) is increasingly employed for the discovery of clinical biomarkers. However, due to sensitivity limitations related to in-source ionization yield, many potential biomarkers are not detected by standard mass spectrometers. Therefore, more efficient ion-source technologies are needed to improve MS applications in biomarker discovery.

METHODS

Among novel ion-source technologies, Surface-Activated Chemical Ionization (SACI), although endowed with high sensitivity linked to its ability to reduce chemical noise in mass spectra, has seen limited application in biomarker discovery to date, due to its selectivity for highly polar compounds. However, in combination with an Electrospray Ionization (ESI) source, SACI selectivity can be enlarged in the range of less polar compounds. To validate the new SACI-ESI approach in biomarker discovery, we applied it to a translational setting in oncology. We performed MS profiles of 101 human serum samples from a male population, aged 40 or older, coming to the clinic for prostate cancer evaluation based on multiple PSA exams, digital rectal examination and echography. The SACI-ESI MS spectra were analyzed and classified with an innovative bioinformatic approach based on the MS-search freeware developed in house.

RESULTS

Here we demonstrate that the SACI-ESI combination can produce MS spectra with greater sensitivity and lower noise than those obtained with the common ESI alone. We found that the SACI-ESI combination increased the number of detectable compounds and produced better quality of profiles in liquid chromatography (LC) coupled with MS (LC/MS) analysis of human serum samples, improving disease prediction potential.

CONCLUSIONS

SACI-ESI can facilitate MS-based discovery of potential biomarkers in human serum. Combined with the proposed bioinformatic approach (based on XCMS and NIST data elaboration) for the analysis of the MS spectra obtained, the potential for developing biomarkers with diagnostic capabilities are demonstrated in a prostate cancer diagnosis clinical setting.

Abstract 2328: Targeting angiogenesis: Anti-docking site peptides to Met receptor and nanotechnology

The Met tyrosine kinase receptor is involved in different cell responses during development and pathological conditions. In cancer, Met can promote growth, invasion, angiogenesis and tumor metastasis following the interaction with its ligand, the hepatocyte growth factor (HGF). We decided to develop angiogenesis inhibitors that target the HGF pathway, impairing tumour neo-vascularization and metastatic spreading. We investigated the anti-angiogenic proprieties of a synthetic peptide mimicking the intracellular Met-tail, which was delivered into cells by fusion with the internalization sequences from Antennapedia or HIV-Tat. We are also trying to do peptide delivery by using carbon nanotubes. In order to evaluate the effect of Met-derived inhibitors on angiogenesis, we treated HUVEC with peptides and we evaluated their ability to interfere with HGF-induced proliferation, migration and morphogenesis of endothelial cells in vitro and angiogenesis. Kaposi's sarcoma (KS), the most frequent neoplasia in patients with AIDS, which originates from endothelial origin and is highly vascularized, shows features compatible with the biological properties of HGF. We used KS as tumour model to test the effect of peptides on tumour growth in vivo. We found that the peptides inhibited ligand-dependent endothelial cell proliferation, migration and morphogenesis in vitro and interfered with HGF-dependent downstream signalling. In vivo, the peptides inhibited HGF-induced angiogenesis and Kaposi's sarcoma tumour growth. We also demonstrated that diacylglycerol kinases (DGK) contribute to the malignant phenotype of KS. The data obtained show that the peptides impair angiogenesis triggered by HGF, suggesting the use of anti-docking site compounds as therapeutic agents to interfere with the angiogenesis process. The development of angiogenesis inhibitors and the identification of new intracellular transducers effective in the high vascularised KS cells, open the possibility of a combination therapy that concomitantly interferes with tumour neo-vascularization and the malignant properties of KS.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2328. doi:1538-7445.AM2012-2328

Diet-derived phytochemicals: from cancer chemoprevention to cardio-oncological prevention

Cardiovascular diseases and cancer are the leading causes of death in most countries. These diseases share many common risk factors as well as pathogenetic determinants, and their incidence is related to age in an exponential manner. Furthermore, it has become apparent that several treatments used in therapy or even in prevention of cancer can impair the structural and functional integrity of the cardiovascular system, giving rise to an interdisciplinary field: cardio-oncology. However, tumors and cardiovascular diseases also share common protective factors: they can be prevented either by avoiding exposure to recognized risk factors, and/or by favoring the intake of protective compounds and by modulating the host defense machinery. These latter approaches are generally known as chemoprevention. A great variety of dietary and pharmacological agents have been shown to be potentially capable of preventing cancer in preclinical models, most of which are of plant origin. Phytochemicals, in particular diet-derived compounds, have therefore been proposed and applied in clinical trials as cancer chemopreventive agents. There is now increasing evidence that some phytochemicals can be also protective for the heart, having the potential to reduce cancer, cardiovascular disease and even anticancer drug-induced cardiotoxicity. We introduce the concept that these compounds induce pre-conditioning, a low level cellular stress that induces strong protective mechanisms conferring resistance to toxins such as cancer chemotherapeutics. Cancer cells and cardiomyocytes have fundamental differences in their metabolism and sensitivity to preconditioning, autophagy and apoptosis, so that dosage of the prevention compounds is important. Here we discuss the mechanisms responsible for the cardiotoxicity of anticancer drugs, the possibility to prevent them and provide examples of diet-derived phytochemicals and other biological substances that could be exploited for protecting the cardiovascular system according to a joint cardio-oncological preventative approach.

Cardio-oncology in targeting the HER receptor family: the puzzle of different cardiotoxicities of HER2 inhibitors

The HER family of tyrosine kinase receptors includes several members that are clinically important targets in cancer therapies, in particular HER1 (the EGF receptor) and HER2, other members include HER3 and HER4. Trastuzumab, a humanized monoclonal antibody and lapatinib, a tyrosine kinase inhibitor, are drugs that target HER2, which is highly expressed in 20-30% of breast cancers. Trastuzumab is recommended as an adjuvant therapy for lymph node positive, HER2-positive breast cancers, or node-negative cancer with high-risk of recurrence, as well as in stage IV cancers. One serious side effect of trastuzumab is cardiomyocyte dysfunction, resulting in reduced heart contractile efficiency. The incidence of collateral effects on the heart with trastuzumab therapy increases in people with cardiovascular risk factors, heart disease and when combined with other chemotherapeutics. When cardiotoxicity was observed with trastuzumab, several studies have addressed potential cardiac damage of trastuzumab itself and lapatinib. The differences in cardiovascular effects of these two compounds are somewhat unexpected and suggest distinct mechanisms of action, which have clear implications in clinical application and prevention of cardiotoxicity in cardio-oncological approaches.

Cancer stem cells and the tumor microenvironment: soloists or choral singers

The idea of cancer stem cell (CSC) has recently moved to the forefront of cancer research. There is still a lack of a widespread consensus on their description and definition. ,The increasing literature on CSCs has compelled researchers worldwide to rewrite the natural history of cancer including those cells as principal players as well as to revise their views on tumor formation and progression. CSCs are tumor cell components that can initiate a new tumor after an apparent therapeutic eradication. A functional definition of cancer stem cell or cancer initiating cell is that of a cell which, when transplanted in a mouse model, can give rise to a tumor recapitulating the original one or even a phenotypically diverse tumor related to the tumor of origin. Since the characteristic asymmetric division of stem cells is somewhat anomalous in cancer, it might be advisable to refer to them as "stemloids". Stemness in cancer is not as much as an identity but rather a status. There is increasing evidence of the importance of the tumor and the host micro-environment in conditioning the stem cell status itself. The cancer stem cell micro-environment may be the key in the development of therapeutic strategies. We must think in terms of targeting "standard" tumor cells, cancer stem cells, and also their niche and tumor micro-environment. Here we discuss some features of cancer stem cells, and the role of the micro-environment, envisaging a choral view of cancer stem cell development and-or latency, towards development of specific therapeutic approaches. Here we propose models of replication and quiescence and the modulation by cells, genes and miRNAs. We also summarize in a table surface makers useful for the identification and isolation of CSCs.

Abstract 3272: A Met receptor docking site peptide fused to cell-penetrating sequences acts as a powerful inhibitor of angiogenesis and vascular tumour growth

Introduction: Hepatocyte growth factor (HGF) is a potent mitogenic, motogenic and morphogenic factor with angiogenic properties; it directly or indirectly stimulates endothelial cells favouring tumour expansion and HGF receptor activation in cancer cells. Kaposi's sarcoma (KS), the most frequent neoplasia in patients with AIDS, which originates from endothelial origin and is highly vascularized, shows features compatible with the biological properties of HGF. We decided to develop angiogenesis inhibitors that target the HGF pathway, impairing tumour neo-vascularization and metastatic spreading. We investigated the anti-angiogenic properties of synthetic peptides mimicking the docking site of Met receptor on human endothelial cells (HUVEC) and KS. We also analyzed the role of diacylglycerol kinases (DGK) in KS cell responses.

Material and methods: To evaluate the effect of Met-derived inhibitors on angiogenesis, we treated HUVEC with peptides containing Met docking site fused to the internalization sequences of Antennapedia homeodomain or of Tat transactivation domain which were used to deliver peptides into living cells. We evaluated the ability of peptides to interfere with HGF-induced proliferation, migration and morphogenesis of endothelial cells in vitro and angiogenesis and tumor growth in vivo. To investigate the role of DGK in the different biological responses elicited by HGF in the Kaposi’ sarcoma cells, we treated KS cells with the DGK pharmacological inhibitor R59949.

Results: We observed that in endothelial cells internalized peptides inhibited ligand-dependent cell proliferation, motility, invasiveness and morphogenesis in vitro, which correlated with interference of HGF-dependent downstream signalling. In vivo, the peptides inhibited HGF-induced angiogenesis and Kaposi's sarcoma tumour growth. DGK plays an essential role in KS cell proliferation.

Conclusion: the data obtained on endothelial cells show that the carboxyl-terminal sequence of Met fused to the internalization sequences of Antennapedia homeodomain or of Tat transactivation domain impairs angiogenesis triggered by HGF, suggesting the use of anti-docking site compounds as therapeutic agents to interfere with the angiogenesis process. The demonstration that DGK is essential for KS growth suggests that these enzymes are promising target for a pharmacological intervention on KS cells. The development of angiogenesis inhibitors and the identification of new intracellular transducers effective in the high vascularised KS cells, open the possibility of a combination therapy that concomitantly interferes with tumour neo-vascularization and the malignant properties of KS.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3272. doi:10.1158/1538-7445.AM2011-3272

Cytokine loaded biopolymers as a novel strategy to study stem cells during wound-healing processes

The biopolymer matrigel loaded with cytokine can be used for the recruitment in vivo of specific cell populations and as a vector for the preparation of cell cultures. Data demonstrate that the injection of the matrigel biopolymer supplemented with interleukin-8 (IL-8) in the leech Hirudo medicinalis can be used to purify cell populations showing the same morphofunctional and molecular mechanisms of specific populations of vertebrate hematopoietic precursor cells involved in tissue repair. These cells spontaneously differentiated into myofibroblasts. This approach highlights how the innovative use of a cytokine-loaded biopolymer for an in vivo cell sorting method, applied to a simple invertebrate model, can be a tool for studying myofibroblast cell biology and its regulation, step by step.

Capecitabine in breast cancer: the issue of cardiotoxicity during fluoropyrimidine treatment

Capecitabine is an orally available fluoropyrimidine carbamate that selectively delivers fluorouracil (5-FU) to tissues expressing high levels of thymidine phosphorylase (TP) such as tumors. The drug has demonstrated efficacy in metastatic breast cancer, colorectal, and pancreatic cancer. Although these are considered safe drugs, a growing body of literature reports adverse cardiac effects. Clinical trials indicate that capecitabine has a cardiac toxicity similar to that of infused fluoropyrimidines such as 5-FU. Here, we review cardiotoxicity in the use of fluoropyrimidines, with particular attention toward capecitabine. We also describe a severe, reversible cardiac event that occurred in a 39-year-old woman, with no cardiac risk factors, treated with capecitabine for advanced breast cancer. This review and our experience confirm that fluoropyrimidine cardiotoxicity is an infrequent but documented side effect. Oncology patients under treatment should be closely observed and monitored for cardiac symptoms with particular attention in case of signs or symptoms of cardiovascular complications. The implementation of cardio-oncology interdisciplinary teams should, in the future, reduce the impact of cancer treatment-associated cardiotoxicity syndromes.

The tumor microenvironment of colorectal cancer: stromal TLR-4 expression as a potential prognostic marker

Background

Colorectal cancer can be efficiently treated when found at early stages, thus the search for novel markers is of paramount importance. Since inflammation is associated with cancer progression and angiogenesis, we investigated expression of cytokines like IL-6 and other mediators that play a key role in the innate immune system, in particular toll like receptor 4 (TLR4), in the microenvironment of lesions from different stages of colon disease progression, from ulcerative colitis to adenoma and adenocarcinoma to find useful markers.

Methods

The presence of inflammatory cells and expression of key cytokines involved in the inflammation process were quantified by immunohistochemistry in specific tissue compartments (epithelial, stromal, endothelial) by immunohistochemistry. A murine azoxymethane/dextran sulfate model in which Tir8, a negative regulator of the inflammatory response, was ablated was used to confirm the clinical observations. 116 Archival tissue samples from patients with different stages of colorectal disease: 13 cases of ulcerative colitis (UC), 34 tubular or tubulo-villous adenomas (AD), and 53 infiltrating adenocarcinomas. 16 specimens of healthy mucosa surgically removed with the cancerous tissue were used as a control.

Results

The differences between healthy tissues and the diverse lesions was characterized by a marked inflammatory-angiogenic reaction, with significantly (P < 0.05) higher numbers of CD68, CD15, and CD31 expressing cells in all diseased tissues that correlated with increasing grade of malignancy. We noted down-regulation of a potential modulator molecule, Hepatocyte Growth Factor, in all diseased tissues (P < 0.05). TLR-4 and IL6 expression in the tumor microenvironment were associated with adenocarcinoma in human samples and in the murine model. We found that adenocarcinoma patients (pT1-4) with higher TLR-4 expression in stromal compartment had a significantly increased risk in disease progression. In those patients with a diagnosis of pT3 (33 cases) colon cancer, those with very high levels of TLR-4 in the tumor stroma relapsed significantly earlier than those with lower expression levels.

Conclusions

These data suggest that high TLR-4 expression in the tumor microenvironment represents a possible marker of disease progression in colon cancer.

Cell delivery of Met docking site peptides inhibit angiogenesis and vascular tumor growth

Hepatocyte growth factor (HGF) and its receptor Met are responsible for a wide variety of cellular responses, both physiologically during embryo development and tissue homeostasis, and pathologically, particularly during tumor growth and dissemination. In cancer, Met can act as an oncogene on tumor cells, as well as a pro-angiogenic factor activating endothelial cells and inducing new vessel formation. Molecules interfering with Met activity could be valuable therapeutic agents. Here we have investigated the antiangiogenic properties of a synthetic peptide mimicking the docking site of the Met carboxyl-terminal tail, which was delivered into the cells by fusion with the internalization sequences from Antennapedia or HIV-Tat. We showed that these peptides inhibit ligand-dependent endothelial cell proliferation, motility, invasiveness and morphogenesis in vitro to an even greater extent and with much less toxicity than the Met inhibitor PHA-665752, which correlated with interference of HGF-dependent downstream signaling. In vivo, the peptides inhibited HGF-induced angiogenesis in the matrigel sponge assay and impaired xenograft tumor growth and vascularization in Kaposi's sarcoma. These data show that interference with the Met receptor intracellular sequence impairs HGF-induced angiogenesis, suggesting the use of antidocking site compounds as a therapeutic strategy to counteract angiogenesis in cancer as well as in other diseases.

The tumor microenvironment: biology of a complex cellular and tissue society

The tumor microenvironment is a "complex society" of many cell types and their extracellular matrix. All these cell types and the matrix take part to the generation of a tumor "tissue". It is well established that preneoplastic proliferating cells cannot give origin to a tumor without an appropriate blood supply. In fact, angiogenesis could be considered the rate limiting step of tumor growth. In this context microenvironment components play a pivotal role in the regulation of the angiogenic switch and in cancer progression. For these reasons the comprehension of biological and molecular mechanisms involved in the relationship between tumor cells and the microenvironment could unveil new therapeutic and preventive approaches to cancer. In this complex scenario molecular imaging of the microenvironment is crucial to dissect cellular and stromal dynamic contributions.

Abstract 562: Stromal TLR4 and IL 6 expression as potential prognostic inflammation-associated markers for colo-rectal cancer progression

Epidemiological studies suggest that chronic inflammatory conditions constitute pre-neoplastic conditions.

To study how chronic inflammation could affect tumor growth and progression, we quantified the presence of inflammatory cells and expression of inflammatory cytokines by immunohistochemistry on archival tissue samples from 116 patients. We considered 13 cases of ulcerative colitis, 34 tubular or tubulo-villous adenomas with low or high grade dysplasia, and 53 infiltrating adenocarcinomas with T1, T2, T3, and T4 staging. Sixteen specimens of healthy mucosa resected along with the cancerous tissue were used as controls. We investigated expression of CD68 (macrophages), CD15 (neutrophils), CD31 (endothelial cells), Interleukin 6 (IL-6), Hepatocyte Growth Factor (HGF), and Toll-Like Receptor 4 (TLR-4). We considered 3 specific tissue compartments: epithelial, stromal and endothelial (vessel associated). Statistical differences between individual cell groups were determined using an unpaired two way t-test (Mann-Whitney).

Progression from healthy tissue to ulcerative colitis was characterized by a massive inflammatory-angiogenic reaction, as for a significant increase in expression of inflammation markers, paralleled by down-regulation of a potential suppressive molecule, HGF. Subsequently, a progressive increase in cells expressing CD68, CD15, TLR-4, and IL6 were found in the passage from adenoma to adenocarcinoma.

Adenocarcinoma patients that expressed high levels of TLR-4 in the stromal compartment had a significantly increased risk of relapse within 40 months. Moreover, in the subgroup of adenocarcinoma patients with a diagnosis of pT3 colon cancer (the most frequent pT), those with higher levels of TLR-4 in the tumor stroma showed increased risk for a relapse within 15 months.

These data suggest that inflammation correlates with progression in colorectal cancer, and that TLR-4 represents a potential prognostic marker of colo-rectal cancer progression.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 562.

Functional genomics of endothelial cells treated with anti-angiogenic or angiopreventive drugs

Angiogenesis is a highly regulated physiological process that has been studied in considerable detail given its importance in several chronic pathologies. Many endogenous factors and hormones intervene in the regulation of angiogensis and classical as well as targeted drugs have been developed for its control. Angiogenesis inhibition has come off the bench and entered into clinical application for cancer therapy, particularly for metastatic disease. While the clinical benefit is currently in terms of months, preclinical data suggest that novel drugs and drug combinations could lead to substantial improvement. The many targets of endogenous angiogenesis inhibitors reflect the complexity of the process; in contrast, current clinical therapies mainly target the vascular endothelial growth factor system. Cancer chemopreventive compounds can retard tumor insurgence and delay or prevent metastasis and many of these molecules hinder angiogenesis, a mechanism that we termed angioprevention. Angiopreventive drugs appear to prevalently act through the inhibition of the pro-inflammatory and anti-apoptotic player NFkappaB, thus contrasting inflammation dependent angiogenesis. Relatively little is known concerning the effects of these angiogenesis inhibitors on gene expression of endothelial cells, the main target of many of these molecules. Here we provide an exhaustive list of anti-angiogenic molecules, and summarize their effects, where known, on the transcriptome and functional genomics of endothelial cells. The regulation of specific genes can be crucial to preventive or therapeutic intervention. Further, novel targets might help to circumvent resistance to anti-angiogenic therapy. The studies we review are relevant not only to cancer but also to other chronic degenerative diseases involving endothelial cells, such as cardiovascular disorders, diabetes, rheumatoid arthritis and retinopaties, as well as vessel aging.