Molecular links between tumor angiogenesis and inflammation: inflammatory stimuli of macrophages and cancer cells as targets for therapeutic strategy

Common mechanisms of dysfunctional adipose tissue and obesity-related cancers

The relation between cancer and metabolic disorders was recognized several decades ago, but the underlying mechanisms involved in cancer development and progression remain obscure. In the last years, many groups have been studying systemic adipose tissue markers in cancer patients. However, few consistent results were obtained. On the other hand, several studies revealed many aspects of adipose tissue physiology in obesity. Nowadays, it is recognized that excessive lipid uptake in adipocytes leads to hypertrophy and consequently to metabolic dysregulation, hypoxia, inflammation, impaired adipocytokine expression and angiogenesis, insulin resistance and macrophage recruitment. In obese patients, tumours commonly colocalize with excessive adipose tissue accumulation, and most of the features of hypertrophic adipose tissue are observed in cancer patients, namely breast and colon. This review aimed to summarize pathological adipose tissue alterations that may contribute to cancer aetiology and development.

Xylitol inhibits in vitro and in vivo angiogenesis by suppressing the NF-κB and Akt signaling pathways

Angiogenesis is an important process involved in tumor growth and metastasis. Many studies have investigated the use of natural compounds such as angiogenic inhibitors. Xylitol is a 5-carbon sugar alcohol and is an artificial sweetener that has been used in chewing gums to prevent tooth decay. Xylitol has been also known to inhibit inflammatory cytokine expression induced by lipopolysaccharide (LPS). Since angiogenesis and inflammation share a common signaling pathway, we investigated the role of xylitol in angiogenesis. Xylitol inhibited the migration, invasion and tube formation of human umbilical vein endothelial cells (HUVECs). Xylitol also inhibited in vivo angiogenesis in a mouse Matrigel plug assay. Furthermore, mRNA expression of vascular endothelial growth factor (VEGF), VEGFR-II (KDR), basic fibroblast growth factor (bFGF), bFGFR-II, matrix metalloproteinase-2 (MMP-2) and MMP-9 of HUVECs decreased following treatment with xylitol. These anti-angiogenic effects of xylitol are exerted through inhibition of NF-κB and Akt activation. Taken together, these results suggest that xylitol acts as a beneficial angiogenesis inhibitor.

Prostaglandin E2 receptor EP1 phosphorylate CREB and mediates MMP2 expression in human cholangiocarcinoma cells

Cyclooxygenase-2 (COX-2) and COX-2-induced prostaglandin E2 (PGE2) have been implicated in all stages of malignant tumorigenesis. Although many aspects of matrix metalloproteinase (MMP2) on tumor invasion have been studied, the exact mechanism of PGE2-induced MMP2 overproduction has not been clearly defined. We have previously demonstrated that PGE2-enhanced extracellular signal-regulated kinase (Erk) phosphorylation via EP1 signaling pathway involved in PGE2-induced cell proliferation. Based on the identification of the transcription factor cyclic AMP response element-binding protein (CREB) as an important regulator of MMP2 and Erk phosphorylate CREB at ser133, we hypothesize that CREB may be implicated in the signaling of PGE2 stimulation to MMP2 overproduction via EP1 receptor. In the study, we investigated the role of EP1 receptor on PGE2-induced MMP2 expression and delineated the signaling pathway that contributes to EP1 receptor modulation of MMP2 in human cholangiocarcinoma cells. We found PGE2 or selective EP1 receptor agonist 17-P-T-PGE2-stimulated MMP2 expression and selective EP1 receptor antagonist SC-51322 or EP1 receptor siRNA abrogated PGE2-induced MMP2 expression. Intracellular calcium chelator BAPTA-AM, the selective inhibitor of EGFR AG1478 and the selective inhibitor of Erk PD98059 blocked EP1 receptor activation-induced CREB phosphorylation and MMP2 expression. A novel dominant-negative (D-N) inhibitor protein of the CREB, termed A-CREB, attenuated EP1 receptor activation-induced MMP2 expression. Our findings suggest that PGE2-enhanced MMP2 expression is, at least in part, mediated through EP1 receptors and calcium signaling pathway-induced CREB phosphorylation in human cholangiocarcinoma cells.

Calorie restriction and cancer prevention: a mechanistic perspective

Calorie restriction (CR) is one of the most potent broadly acting dietary interventions for inducing weight loss and for inhibiting cancer in experimental models. Translation of the mechanistic lessons learned from research on CR to cancer prevention strategies in human beings is important given the high prevalence of excess energy intake, obesity, and metabolic syndrome in many parts of the world and the established links between obesity-associated metabolic perturbations and increased risk or progression of many types of cancer. This review synthesizes findings on the biological mechanisms underlying many of the anticancer effects of CR, with emphasis on the impact of CR on growth factor signaling pathways, inflammation, cellular and systemic energy homeostasis pathways, vascular perturbations, and the tumor microenvironment. These CR-responsive pathways and processes represent targets for translating CR research into effective cancer prevention strategies in human beings.

Modulators of HIF1α and NFkB in Cancer Treatment: Is it a Rational Approach for Controlling Malignant Progression?

HIF1α and NFkB are two transcription factors very frequently activated in tumors and involved in tumor growth, progression, and resistance to chemotherapy. In fact, HIF1α and NFkB together regulate transcription of over a thousand genes that, in turn, control vital cellular processes such as adaptation to the hypoxia, metabolic reprograming, inflammatory reparative response, extracellular matrix digestion, migration and invasion, adhesion, etc. Because of this wide involvement they could control in an integrated manner the origin of the malignant phenotype. Interestingly, hypoxia and inflammation have been sequentially bridged in tumors by the discovery that alarmin receptors genes such as RAGE, P2X7, and some TLRs, are activated by HIF1α; and that, in turn, alarmin receptors strongly activate NFkB and proinflammatory gene expression, evidencing all the hallmarks of the malignant phenotype. Recently, a large number of drugs have been identified that inhibit one or both transcription factors with promising results in terms of controlling tumor progression. In addition, many of these molecules are natural compounds or off-label drugs already used to cure other pathologies. Some of them are undergoing clinical trials and soon they will be used alone or in combination with standard anti-tumoral agents to achieve a better treatment of tumors with reduction of metastasis formation and, more importantly, with a net increase in survival. This review highlights the central role of HIF1α activated in hypoxic regions of the tumor, of NFkB activation and proinflammatory gene expression in transformed cells to understand their progression toward malignancy. Different molecules and strategies to inhibit these transcription factors will be reviewed. Finally, the central role of a new class of deacetylases called Sirtuins in regulating HIF1α and NFkB activity will be outlined.

7-Ketocholesterol induces inflammation and angiogenesis in vivo: a novel rat model

Accumulation of 7-Ketocholesterol (7KCh) in lipid deposits has been implicated in a variety of chronic diseases including atherosclerosis, Alzheimer's disease and age-related macular degeneration. 7KCh is known to be pro-inflammatory and cytotoxic to various types of cultured cells but little is known about its effects in vivo. In this study we have investigated the effects of 7KCh in vivo by implanting biodegradable wafers into the anterior chamber of the rat eye. The wafers were prepared using a mixture of two biodegradable polymers with different amounts of 7KCh. The 7KCh-containing implants induced massive angiogenesis and inflammation. By contrast, no angiogenesis and very little inflammation were observed with cholesterol-containing implants. The neovessel growth was monitored by fluorescein angiography. Neovessels were observed 4 days post implantation and peaked between 7 to 10 days. The angiography and isolectin IB(4) labeling demonstrated that the neovessels originated from the limbus and grew through the cornea. Immunolabeling with anti-CD68 suggested that the 7KCh-containing implants had extensive macrophage infiltration as well as other cell types. A significant increase in VEGF was also observed in 7KCh-containing implants by fluorescent immunolabeling and by immunoblot of the aqueous humor (AH). Direct measurement of VEGF, IL-1β and GRO/KC demonstrated a marked elevation of these factors in the AH of the 7KCh-implants. In summary this study demonstrates two important things: 1) 7KCh is pro-angiogenic and pro-inflammatory in vivo and 2) implants containing 7KCh may be used to create a novel angiogenesis model in rats.

Upregulation of miRNA-155 promotes tumour angiogenesis by targeting VHL and is associated with poor prognosis and triple-negative breast cancer

MicroRNA-155 (miR-155) is frequently up-regulated in various types of human cancer; however, its role in cancer angiogenesis remains unknown. Here, we demonstrate the role of miR-155 in angiogenesis through targeting von Hippel-Lindau tumour suppressor (VHL) in breast cancer. Ectopic expression of miR-155 induced whereas knockdown of miR-155 inhibited HUVEC network formation, proliferation, invasion, and migration. Furthermore, mammary fat pad xenotransplantation of ectopically expressed miR-155 resulted in extensive angiogenesis, proliferation, tumour necrosis, and recruitment of pro-inflammatory cells such as tumour associated macrophages. Expression of VHL abrogated these miR-155 effects. Moreover, miR-155 expression inversely correlates with VHL expression level and is associated with late stage, lymph node metastasis, and poor prognosis as well as triple-negative tumour in breast cancer. These findings indicate that miR-155 plays a pivotal role in tumour angiogenesis by downregulation of VHL, and provide a basis for miR-155-expressing tumours to embody an aggressive malignant phenotype, and therefore, miR-155 is an important therapeutic target in breast cancer.

Functional microRNAs in Alzheimer's disease and cancer: differential regulation of common mechanisms and pathways

Two of the main research priorities in the United States are cancer and neurodegenerative diseases, which are attributed to abnormal patterns of cellular behavior. MicroRNAs (miRNA) have been implicated as regulators of cellular metabolism, and thus are an active topic of investigation in both disease areas. There is presently a more extensive body of work on the role of miRNAs in cancer compared to neurodegenerative diseases, and therefore it may be useful to examine whether there is any concordance between the functional roles of miRNAs in these diseases. As a case study, the roles of miRNAs in Alzheimer's disease (AD) and their functions in various cancers will be compared. A number of miRNA expression patterns are altered in individuals with AD compared with healthy older adults. Among these, some have also been shown to correlate with neuropathological changes including plaque and tangle accumulation, as well as expression levels of other molecules known to be involved in disease pathology. Importantly, these miRNAs have also been shown to have differential expression and or functional roles in various types of cancer. To examine possible intersections between miRNA functions in cancer and AD, we review the current literature on these miRNAs in cancer and AD, focusing on their roles in known biological pathways. We propose a pathway-driven model in which some molecular processes show an inverse relationship between cancer and neurodegenerative disease (e.g., proliferation and apoptosis) whereas others are more parallel in their activity (e.g., immune activation and inflammation). A critical review of these and other molecular mechanisms in cancer may shed light on the pathophysiology of AD, and highlight key areas for future research. Conclusions from this work may be extended to other neurodegenerative diseases for which some molecular pathways have been identified but which have not yet been extensively researched for miRNA involvement.

The role of pattern recognition receptors in intestinal inflammation

Recognition of microorganisms by pattern-recognition receptors (PRRs) is the primary component of innate immunity that is responsible for the maintenance of host-microbial interactions in intestinal mucosa. Dysregulation in host-commensal interactions has been implicated as the central pathogenesis of inflammatory bowel disease (IBD), which predisposes to developing colorectal cancer. Recent animal studies have begun to outline some unique physiology and pathology involving each PRR signaling in the intestine. The major roles played by PRRs in the gut appear to be the regulation of the number and the composition of commensal bacteria, epithelial proliferation, and mucosal permeability in response to epithelial injury. In addition, PRR signaling in lamina propria immune cells may be involved in induction of inflammation in response to invasion of pathogens. Because some PRR-deficient mice have shown variable susceptibility to colitis, the outcome of intestinal inflammation may be modified depending on PRR signaling in epithelial cells, immune cells, and the composition of commensal flora. Through recent findings in animal models of IBD, this review will discuss how abnormal PRR signaling may contribute to the pathogenesis of inflammation and inflammation-associated tumorigenesis in the intestine.

CDA-2, a urinary preparation, inhibits lung cancer development through the suppression of NF-kappaB activation in myeloid cell

CDA-2 (cell differentiation agent 2), a urinary preparation, has potent anti- proliferative and pro-apoptotic properties in cancer cells. However, the mechanisms of tumor inhibitory action of CDA-2 are far from clear, and especially there was no report on lung cancer. Here we demonstrate that CDA-2 and its main component phenylacetylglutamine (PG) reduce the metastatic lung tumor growth, and increases survival time after inoculation with Lewis lung carcinoma (LLC) cells in a dose-dependent manner in C57BL6 mice. Proliferative program analysis in cancer cells revealed a fundamental impact of CDA-2 and PG on proliferation and apoptosis, including Bcl-2, Bcl-XL, cIAP1, Survivin, PCNA, Ki-67 proteins and TUNEL assays. CDA-2 and PG significantly reduced NF-κB DNA-binding activity in lung cancer cells and in alveolar macrophages of tumor bearing mice and especially decreased the release of inflammatory factors including TNFα, IL-6, and KC. Furthermore, CDA-2 and PG decrease the expressions of TLR2, TLR6, and CD14, but not TLR1, TLR3, TLR4, and TLR9 in bone-marrow-derived macrophages (BMDM) of mice stimulated by LLC-conditioned medium (LLC-CM). Over-expressing TLR2 in BMDM prevented CDA-2 and PG from inhibiting NF-κB activation, as well as induction of TNFα and IL-6. TLR2:TLR6 complexes mediate the effect of NF-κB inactivation by CDA-2. In conclusion, CDA-2 potently inhibits lung tumor development by reduction of the inflammation in lung through suppression of NF-κB activation in myeloid cells, associating with modulation of TLR2 signaling.

EGCG targeting efficacy of NF-κB downstream gene products is dictated by the monocytic/macrophagic differentiation status of promyelocytic leukemia cells

Central nervous system infiltration by circulating leukemic cells and enhanced in vitro transendothelial migration of promyelocytic leukemia HL-60-derived macrophages through a blood-brain barrier model was recently demonstrated. The intrinsic molecular and signaling mechanisms involved are, however, poorly documented. Drug targeting of such translocation event performed by circulating microbes and immune cells may prevent secondary cerebral infections and development of brain pathologies. In this study, we specifically investigated the in vitro targeting efficacy of the chemopreventive and dietary-derived epigallocatechin-3-gallate (EGCG) molecule on the NF-κB-mediated transcriptional regulation of a panel of 89 biomarkers associated with promyelocytic HL-60 differentiation into macrophages. NF-κB-mediated signaling during HL-60 macrophage differentiation was reversed by EGCG, in part through reduced IκB phosphorylation and led to the inhibition of moderately to highly expressed NF-κB gene targets among which the matrix metalloproteinase (MMP)-9 and the cyclooxygenase (COX)-2. In contrast, EGCG exhibited low efficacy in reversing NF-κB-regulated genes and showed selective antagonism toward COX-2 expression while that of MMP-9 remained high in terminally differentiated macrophages. Decreased expression of the 67-kDa non-integrin Laminin Receptor in terminally differentiated macrophages may explain such differential EGCG efficacy. Our results suggest that terminally differentiated macrophage transendothelial migration associated with neuroinflammation may not be pharmacologically affected by such a specific class of flavonoid. The differentiation status of a given in vitro cell model must therefore be carefully considered for optimized assessment of therapeutic drugs.

Linking tumor-associated macrophages, inflammation, and intestinal tumorigenesis: role of MCP-1

Tumor-associated macrophages are associated with poor prognosis in certain cancers. Monocyte chemoattractant protein 1 (MCP-1) is thought to be the most important chemokine for recruitment of macrophages to the tumor microenvironment. However, its role on tumorigenesis in a genetic mouse model of colon cancer has not been explored. We examined the role of MCP-1 on tumor-associated macrophages, inflammation, and intestinal tumorigenesis. Male Apc(Min/+), Apc(Min/+)/MCP-1(-/-) or wild-type mice were euthanized at 18 wk of age and intestines were analyzed for polyp burden, apoptosis, proliferation, β-catenin, macrophage number and phenotype, markers for cytotoxic T lymphocytes and regulatory T cells, and inflammatory mediators. MCP-1 deficiency decreased overall polyp number by 20% and specifically large polyp number by 45% (P < 0.05). This was consistent with an increase in apoptotic cells (P < 0.05), but there was no change detected in proliferation or β-catenin. MCP-1 deficiency decreased F4/80-positive cells in both the polyp tissue and surrounding intestinal tissue (P < 0.05) as well as expression of markers associated with M1 (IL-12 and IL-23) and M2 macrophages (IL-13, CD206, TGF-β, and CCL17) (P < 0.05). MCP-1 knockout was also associated with increased cytotoxic T lymphocytes and decreased regulatory T cells (P < 0.05). In addition, MCP-1(-/-) offset the increased mRNA expression of IL-1β and IL-6 in intestinal tissue and IL-1β and TNF-α in polyp tissue (P < 0.05), and prevented the decrease in SOCS1 expression (P < 0.05). We demonstrate that MCP-1 is an important mediator of tumor growth and immune regulation that may serve as an important biomarker and/or therapeutic target in colon cancer.

Activated macrophages induce neovascularization through upregulation of MMP-9 and VEGF in rat corneas

PURPOSE

To explore the mechanisms of activated macrophages (A-Mφ) involved in corneal angiogenesis.

METHODS

Activated macrophages were elicited by mineral oil lumbar injection and implanted into corneal micropockets in rats for the treatment group, A-Mφ, and phosphate-buffered saline group as control. Corneal changes were observed with a slit lamp microscope, and histopathological features were evaluated by immunofluorescence. Reverse transcription-polymerase chain reaction was used to detect the relative expression of angiogenesis-associated factors and inflammatory mediators in the activated macrophages and corneal tissue after implantation.

RESULTS

Immunofluorescence showed that peritoneal cells expressed antigens of cluster of differentiation 68 (CD68, ED1), matrix metalloproteinases-9 (MMP-9), and vascular endothelial growth factor (VEGF). Activated macrophages significantly induced corneal neovascularization (CNV), which peaked on day 5, whereas the control group and normal corneas showed less CNV. The activated macrophages and corneal tissue after implantation expressed the angiogenesis-related factors, such as cyclooxygenase-2, platelet-derived growth factor, transforming growth factor beta, interleukin-1 alpha, MMP-9, and VEGF in messenger RNA (mRNA). However, mRNA expression of MMP-9 and VEGF differed significantly only in the cornea between the A-Mφ group and phosphate-buffered saline group 5 days after the implantation. MMP-9 and VEGF expression of mRNA and protein was higher in the A-Mφ group than that in the control group and normal corneas.

CONCLUSIONS

Activated macrophages induce obvious CNV and related mechanisms, which may be correlated with MMP-9 and VEGF autocrine in activated macrophages and upregulation of MMP-9 and VEGF in corneal tissue.

Growth signals, inflammation, and vascular perturbations: mechanistic links between obesity, metabolic syndrome, and cancer

Nearly 35% of adults and 20% of children in the United States are obese, defined as a body mass index ≥ 30 kg/m(2). Obesity, which is accompanied by metabolic dysregulation often manifesting in the metabolic syndrome, is an established risk factor for many cancers. Within the growth-promoting, proinflammatory environment of the obese state, cross talk between macrophages, adipocytes, and epithelial cells occurs via obesity-associated hormones, cytokines, and other mediators that may enhance cancer risk and progression. This review synthesizes the evidence on key biological mechanisms underlying the obesity-cancer link, with particular emphasis on obesity-associated enhancements in growth factor signaling, inflammation, and vascular integrity processes. These interrelated pathways represent possible mechanistic targets for disrupting the obesity-cancer link.

Angiogenesis inhibitor vasohibin-1 enhances stress resistance of endothelial cells via induction of SOD2 and SIRT1

Vasohibin-1 (VASH1) is isolated as an endothelial cell (EC)-produced angiogenesis inhibitor. We questioned whether VASH1 plays any role besides angiogenesis inhibition, knocked-down or overexpressed VASH1 in ECs, and examined the changes of EC property. Knock-down of VASH1 induced premature senescence of ECs, and those ECs were easily killed by cellular stresses. In contrast, overexpression of VASH1 made ECs resistant to premature senescence and cell death caused by cellular stresses. The synthesis of VASH1 was regulated by HuR-mediated post-transcriptional regulation. We sought to define the underlying mechanism. VASH1 increased the expression of (superoxide dismutase 2) SOD2, an enzyme known to quench reactive oxygen species (ROS). Simultaneously, VASH1 augmented the synthesis of sirtuin 1 (SIRT1), an anti-aging protein, which improved stress tolerance. Paraquat generates ROS and causes organ damage when administered in vivo. More VASH1 (+/-) mice died due to acute lung injury caused by paraquat. Intratracheal administration of an adenovirus vector encoding human VASH1 augmented SOD2 and SIRT1 expression in the lungs and prevented acute lung injury caused by paraquat. Thus, VASH1 is a critical factor that improves the stress tolerance of ECs via the induction of SOD2 and SIRT1.

Revascularization of pancreatic islet allografts is enhanced by α-1-antitrypsin under anti-inflammatory conditions

Pancreatic islets are a highly vascularized entity, and their transplantation into diabetic individuals requires optimal revascularization. In addition, β-cells in islets are extremely sensitive to inflammation. α-1-Antitrypsin (AAT), a circulating serine-protease inhibitor that is available for clinical use as an affinity-purified human product, has been shown to protect islets from graft failure in mouse transplantation models and to achieve readily vascularized islet grafts. AAT is known to induce vascular endothelial growth factor (VEGF) expression and release, as well as protect from proteolytic cleavage of VEGF by elastase, promote viability of endothelial cells, and enhance migration of myocytes. Our aim was to examine whether AAT enhances vasculogenesis toward islet grafts. We employed Matrigel-islet plugs as means to introduce islets in an explantable isolated compartment and examined vessel formation, vessel maturation, and inflammatory profile of explants 9 days after implantation. Also, we examined primary epithelial cell grafts that were prepared from lungs of mice that are transgenic for human AAT. In addition, aortic ring sprouting assay was performed, and HUVEC tube formation assays were studied in the presence of AAT. Our findings indicate that islet grafts exhibit mature vessels in the presence of AAT, as demonstrated by morphology, as well as expression of endothelial CD31, smooth muscle actin (SMA), and von Willebrand factor (vWF). Epithelial cells that express human AAT achieved a similar positive outcome. Aortic ring sprouting was enhanced in AAT-treated cultures and also in cultures that contained primary epithelial cells from human AAT transgenic animals in the absence of added AAT. According to the tube formation assay, HUVECs exhibited superior responses in the presence of AAT. We conclude that vasculogenesis toward islet grafts is enhanced in the presence of AAT. Together with the remarkable safety profile of AAT, the study supports its use in the relevant clinical setups.

The combination of the histone deacetylase inhibitor vorinostat and synthetic triterpenoids reduces tumorigenesis in mouse models of cancer

Novel drugs and drug combinations are needed for the chemoprevention and treatment of cancer. We show that the histone deacetylase inhibitor vorinostat [suberoylanilide hydroxamic acid (SAHA)] and the methyl ester or ethyl amide derivatives of the synthetic triterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO-Me and CDDO-Ea, respectively) cooperated to inhibit the de novo synthesis of nitric oxide in RAW 264.7 macrophage-like cells and in primary mouse peritoneal macrophages. Additionally, SAHA enhanced the ability of synthetic triterpenoids to delay formation of estrogen receptor-negative mammary tumors in MMTV-polyoma middle T (PyMT) mice. CDDO-Me (50 mg/kg diet) and SAHA (250 mg/kg diet) each significantly delayed the initial development of tumors by 4 (P < 0.001) and 2 (P < 0.05) weeks, respectively, compared with the control group in the time required to reach 50% tumor incidence. CDDO-Ea (400 mg/kg diet), as a single agent, did not delay tumor development. The combination of either triterpenoid with SAHA was significantly more potent than the individual drugs for delaying tumor development, with a 7 week (P < 0.001) delay before 50% tumor incidence was reached. SAHA, alone and in combination with CDDO-Me, also significantly (P < 0.05) inhibited the infiltration of tumor-associated macrophages into the mammary glands of PyMT mice and levels of the chemokine macrophage colony-stimulating factor in primary PyMT tumor cells. In addition, SAHA and the synthetic triterpenoids cooperated to suppress secreted levels of the pro-angiogenic factor matrix metalloproteinase-9. Similar results were observed in mouse models of pancreatic and lung cancer. At concentrations that were anti-inflammatory, SAHA had no effect on histone acetylation. These studies suggest that both SAHA and triterpenoids effectively delay tumorigenesis, thereby demonstrating a promising, novel drug combination for chemoprevention.

Silibinin modulates TNF-α and IFN-γ mediated signaling to regulate COX2 and iNOS expression in tumorigenic mouse lung epithelial LM2 cells

Silibinin inhibits mouse lung tumorigenesis in part by targeting tumor microenvironment. Tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) can be pro- or anti-tumorigenic, but in lung cancer cell lines they induce pro-inflammatory enzymes cyclooxygenase 2 (COX2) and inducible nitric oxide synthase (iNOS). Accordingly, here we examined mechanism of silibinin action on TNF-α + IFN-γ (hereafter referred as cytokine mixture) elicited signaling in tumor-derived mouse lung epithelial LM2 cells. Both signal transducers and activators of the transcription (STAT)3 (tyr705 and ser727) and STAT1 (tyr701) were activated within 15 min of cytokine mixture exposure, while STAT1 (ser727) activated after 3 h. Cytokine mixture also activated Erk1/2 and caused an increase in both COX2 and iNOS levels. Pretreatment of cells with a MEK, NF-κB, and/or epidermal growth factor receptor (EGFR) inhibitor inhibited cytokine mixture-induced activation of Erk1/2, NF-κB, or EGFR, respectively, and strongly decreased phosphorylation of STAT3 and STAT1 and expression of COX2 and iNOS. Also, janus family kinases (JAK)1 and JAK2 inhibitors specifically decreased cytokine-induced iNOS expression, suggesting possible roles of JAK1, JAK2, Erk1/2, NF-κB, and EGFR in cytokine mixture-caused induction of COX2 and iNOS expression via STAT3/STAT1 activation in LM2 cells. Importantly, silibinin pretreatment inhibited cytokine mixture-induced phosphorylation of STAT3, STAT1, and Erk1/2, NF-κB-DNA binding, and expression of COX2, iNOS, matrix metalloproteinases (MMP)2, and MMP9, which was mediated through impairment of STAT3 and STAT1 nuclear localization. Silibinin also inhibited cytokine mixture-induced migration of LM2 cells. Together, we showed that STAT3 and STAT1 could be valuable chemopreventive and therapeutic targets within the lung tumor microenvironment in addition to being targets within tumor itself, and that silibinin inhibits their activation as a plausible mechanism of its efficacy against lung cancer.

Macrophages regulate smooth muscle differentiation of mesenchymal stem cells via a prostaglandin F₂α-mediated paracrine mechanism

OBJECTIVE

Mesenchymal stem cells are useful for vascular regeneration of injured tissues. Macrophages are involved in acute or chronic inflammatory diseases, and interleukin-1β (IL-1β), a proinflammatory cytokine, plays a key role in the activation of macrophages within injured tissues. To explore the role of macrophages on mesenchymal stem cell-mediated vascular regeneration, we examined the effects of IL-1β-activated macrophages on differentiation of human adipose tissue-derived mesenchymal stem cells (hASCs) to smooth muscle cells (SMCs) and the vascular regenerative capacity of the differentiated SMCs in a hindlimb ischemia animal model.

METHODS AND RESULTS

We demonstrate that IL-1β-conditioned medium from RAW 264.7 macrophages induces differentiation of human adipose tissue-derived mesenchymal stem cells to α-smooth muscle actin-positive SMCs, and the differentiated SMCs exhibited increased contractility in response to KCl and carbachol treatment. Transplantation of the differentiated SMCs attenuated severe hindlimb ischemia and promoted vascular regeneration. IL-1β treatment stimulated secretion of prostaglandin F(2α) from RAW 264.7 cells. Small interfering RNA-mediated silencing of the prostaglandin F(2α) receptor completely abrogated IL-1β conditioned medium-stimulated α-smooth muscle actin expression. Moreover, prostaglandin F(2α) treatment stimulated expression of α-smooth muscle actin in human adipose tissue-derived mesenchymal stem cells.

CONCLUSIONS

These results suggest that IL-1β-activated macrophages promote differentiation of human adipose tissue-derived mesenchymal stem cells to SMCs through a prostaglandin F(2α)-mediated paracrine mechanism.

Betaine inhibits in vitro and in vivo angiogenesis through suppression of the NF-κB and Akt signaling pathways

Angiogenesis is defined as the formation of new blood vessels form existing vessels surrounding a tumor. The process of angiogenesis is an important step for tumor growth and metastasis, as is inflammation. Thus, angiogenesis inhibitors that suppress inflammation have been studied as an anticancer treatment. Recently, many research groups have investigated the anti-angiogenic activity of natural compounds since some have been demonstrated to have anticancer properties. Among many natural compounds, we focused on betaine, which is known to suppress inflammation. Betaine, trimethylglycine (TMG), was first discovered in the juice of sugar beets and was later shown to be present in wheat, shellfish and spinach. In Southeast Asia, betaine is used in traditional oriental medicine for the treatment of hepatic disorders. Here, we report the anti-angiogenic action of betaine. Betaine inhibited in vitro angiogenic cascade, tube formation, migration and invasion of human umbilical vein endothelial cells (HUVECs). Betaine also inhibited in vivo angiogenesis in the mouse Matrigel plug assay. The mRNA expression levels of basic fibroblast growth factor (bFGF), matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in HUVECs were decreased by betaine treatment. In addition, betaine suppressed NF-κB and Akt activation.

Multilevel regulation of HIF-1 signaling by TTP

Phosphorylation of the RNA-binding protein tristetraprolin (TTP) by p38 MAPK/MK2 does not prevent its RNA interaction and switches the mode of TTP action from destabilization to stabilization of the HIF-1α mRNA and subsequent activation of HIF-1 signaling.

Hypoxia-inducible factor-1 (HIF-1) is a well-studied transcription factor mediating cellular adaptation to hypoxia. It also plays a crucial role under normoxic conditions, such as in inflammation, where its regulation is less well understood. The 3′-untranslated region (UTR) of HIF-1α mRNA is among the most conserved UTRs in the genome, hinting toward posttranscriptional regulation. To identify potential trans factors, we analyzed a large compilation of expression data. In contrast to its known function of being a negative regulator, we found that tristetraprolin (TTP) positively correlates with HIF-1 target genes. Mathematical modeling predicts that an additional level of posttranslational regulation of TTP can explain the observed positive correlation between TTP and HIF-1 signaling. Mechanistic studies revealed that TTP indeed changes its mode of regulation from destabilizing to stabilizing HIF-1α mRNA upon phosphorylation by p38 mitogen-activated protein kinase (MAPK)/MAPK-activated protein kinase 2. Using a model of monocyte-to-macrophage differentiation, we show that TTP-driven HIF-1α mRNA stabilization is crucial for cell migration. This demonstrates the physiological importance of a hitherto-unknown mechanism for multilevel regulation of HIF-1α in normoxia.

The lL-8 and IL-13 gene polymorphisms in inflammatory bowel disease and colorectal cancer

Inflammatory bowel diseases (IBD) and colorectal cancer (CRC) are disorders that originate from immune disturbances. In our study, we evaluated the association between the -251 T/A interleukin (IL)-8 and the -1112 C/T IL-13 polymorphisms, the risk of IBD, and CRC development. Genotypes were determined by PCR-restriction fragment length polymorphism in 191 patients with CRC, 150 subjects with IBD, and 205 healthy controls. We found an association between CRC and the presence of the -251 TA genotype and A allele of the IL-8 gene (odds ratios [ORs] 2.28 and 1.65). A similar relationship was observed between these polymorphic variants and ulcerative colitis (OR 2.05 for the -251 TA genotype and OR 1.47 for the -251 A allele) as well as Crohn's disease (ORs 3.11 and 1.56, respectively). Our research also revealed that the CT and TT genotypes of the IL-13 -1112 C/T polymorphism may be connected with a higher risk of CRC (ORs 2.28 and 1.65). The same genotypes affected the susceptibility of IBD (ORs 2.26 and 3.72). Our data showed that the IL-8 -251 T/A and IL-13 -1112 C/T polymorphisms might be associated with the IBD and CRC occurrence and might be used as predictive factors of these diseases in a Polish population.

Incomplete thermal ablation stimulates proliferation of residual renal carcinoma cells in a translational murine model

What's known on the subject? and What does the study add? Thermal ablation influences the local tissue microenvironment. Several studies have reported that residual tumour cells may exhibit a more aggressive phenotype. This study shows that incomplete CA and RFA cause an increased proliferation and decreased apptosis of residual renal tumour cells. This may be caused by stimulatory factors such as hypoxia, HSPs and inflammatory cells.

OBJECTIVE

To compare the effect of incomplete thermal ablation vs partial nephrectomy (PN) on growth stimulation and cellular survival in renal tumours.

MATERIALS AND METHODS

Renca renal tumours were transplanted under the renal capsule of mice (four to six mice/group) after which incomplete radiofrequency ablation (RFA), cryoablation (CA) or PN was performed. At several time points after treatment, presence of cell proliferation, apoptosis, hypoxic areas, inflammatory factors and the heat-shock proteins (HSPs) 70 and 90 were evaluated using immunohistochemistry.

RESULTS

At 2 h after thermal ablation residual tumour cells showed increased proliferation. This hyperproliferation was significantly stronger after RFA than CA (P < 0.05) and not present after PN. Residual cells showed increased apoptosis after 2 h and decreased apoptosis from 2 days after thermal ablation. Apoptotic cells were significantly less evident at 3 days after RFA (P < 0.001). Hypoxic areas and HSPs were increasingly present from 2 h up to 7 days after thermal ablation (P < 0.001). Inflammatory cells infiltrated mainly the necrotic areas after thermal ablation, and their abundance peaked at 1 week after ablation (P < 0.05). The increased cell growth was preceded by hypoxia and presence of HSPs.

CONCLUSIONS

CA and RFA result in an increased proliferation and decreased apoptosis of residual renal tumour cells. This hyperproliferation may be caused by stimulatory factors, e.g. hypoxia, HSPs and inflammatory cells, and could facilitate recurrences of renal tumours after thermal ablation. This study highlights the importance of achieving complete tumour destruction.

Human adipose tissue macrophages display activation of cancer-related pathways

Obesity is associated with a significantly increased risk for cancer suggesting that adipose tissue dysfunctions might play a crucial role therein. Macrophages play important roles in adipose tissue as well as in cancers. Here, we studied whether human adipose tissue macrophages (ATM) modulate cancer cell function. Therefore, ATM were isolated and compared with monocyte-derived macrophages (MDM) from the same obese patients. ATM, but not MDM, were found to secrete factors inducing inflammation and lipid accumulation in human T47D and HT-29 cancer cells. Gene expression profile comparison of ATM and MDM revealed overexpression of functional clusters, such as cytokine-cytokine receptor interaction (especially CXC-chemokine) signaling as well as cancer-related pathways, in ATM. Comparison with gene expression profiles of human tumor-associated macrophages showed that ATM, but not MDM resemble tumor-associated macrophages. Indirect co-culture experiments demonstrated that factors secreted by preadipocytes, but not mature adipocytes, confer an ATM-like phenotype to MDM. Finally, the concentrations of ATM-secreted factors related to cancer are elevated in serum of obese subjects. In conclusion, ATM may thus modulate the cancer cell phenotype.

EET signaling in cancer

Inflammation and angiogenesis in the tumor microenvironment are increasingly implicated in tumorigenesis. Endogenously produced lipid autacoids, locally acting small-molecule mediators, play a central role in inflammation and tissue homeostasis. These lipid mediators, collectively referred to as eicosanoids, have recently been implicated in cancer. Although eicosanoids, including prostaglandins and leukotrienes, are best known as products of arachidonic acid metabolism by cyclooxygenases and lipoxygenases, arachidonic acid is also a substrate for another enzymatic pathway, the cytochrome P450 (CYP) system. This eicosanoid pathway consists of two main branches: ω-hydroxylases which converts arachidonic acid to hydroxyeicosatetraenoic acids (HETEs) and epoxygenases which converts it to four regioisomeric epoxyeicosatrienoic acids (EETs; 5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET). EETs regulate inflammation and vascular tone. The bioactive EETs are produced predominantly in the endothelium and are mainly metabolized by soluble epoxide hydrolase to less active dihydroxyeicosatrienoic acids. EET signaling was originally studied in conjunction with inflammatory and cardiovascular disease. Arachidonic acid and its metabolites have recently stimulated great interest in cancer biology. To date, most research on eicosanoids in cancer has focused on the COX and LOX pathways. In contrast, the role of cytochrome P450-derived eicosanoids, such as EETs and HETEs, in cancer has received little attention. While CYP epoxygenases are expressed in human cancers and promote human cancer metastasis, the role of EETs (the direct products of CYP epoxygenases) in cancer remains poorly characterized. In this review, the emerging role of EET signaling in angiogenesis, inflammation, and cancer is discussed.

Protein biomarkers of ovarian cancer: the forest and the trees

The goal of effective population-based screening for ovarian cancer remains elusive despite intense efforts aimed at improving upon biomarker and imaging modalities. While dozens of potential serum biomarkers for ovarian cancer have been identified in recent years, none have yet overcome the limitations that have hindered the clinical use of CA-125. Avenues of opportunity in biomarker development are emerging as investigators are beginning to appreciate the significance of remote, as well as local or regional, sources of biomarkers in the construction of diagnostic panels, as well as the importance of evaluating biomarkers in prediagnostic settings. As the list of candidate biomarkers of ovarian cancer continues to grow, refinements in the methods through which specific proteins are selected for further development as components of diagnostic panels are desperately sought. Such refinements must take into account both the bioinformatic and biological significance of each candidate. Approaches incorporating these considerations may potentially overcome the challenges to early detection posed by the histological heterogeneity of ovarian cancer. Here, we review the recent progress achieved in efforts to develop diagnostic biomarker panels for ovarian cancer and discuss the challenges that remain.

Regulation of Th1/Th2 polarization by tissue inhibitor of metalloproteinase-3 via modulating dendritic cells

Tissue inhibitor of metalloproteinase-3 (TIMP-3) is one of a family of proteins inhibiting matrix metalloproteinases, which has also been identified as a mediator for checking inflammation. Meanwhile, it is well known that inflammation causes the activation of the immune response. However, it is not clear whether TIMP-3 plays a role in the immune system. In the present study, we demonstrated a novel function of TIMP-3 in Th1/Th2 polarization through its influence on the antigen-presenting cells. First, TIMP-3 was found strikingly up-regulated by IL-4 during the differentiation of human dendritic cells via the p38MAPK pathway. Second, the expression of costimulatory molecule-CD86 was repressed by TIMP-3. Besides, the induction of IL-12 in matured dendritic cells was significantly inhibited in a PI3K-dependent manner. Furthermore, dendritic cells matured in the presence of TIMP-3 could stimulate allogeneic naive T helper (Th) cells to display a prominent Th2 polarization. Importantly, in an autoimmune disorder-primary immune thrombocytopenia, TIMP-3 showed a statistically positive correlation with IL-4 and platelet count, but a negative correlation with IFN-γ in patient blood samples. Collectively, these in vitro and in vivo data clearly suggested a novel role of TIMP-3 in Th1/Th2 balance in humans.

The synthetic triterpenoid CDDO-methyl ester delays estrogen receptor-negative mammary carcinogenesis in polyoma middle T mice

Novel drugs are needed for the prevention and treatment of breast cancer. Synthetic triterpenoids are a promising new class of compounds with activity in a variety of preclinical cancer models. We tested activity of the methyl ester derivative of the synthetic triterpenoid, 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO-Me), in a relevant model of estrogen receptor-negative breast cancer, the polyoma-middle T (PyMT), in which the oncoprotein drives carcinogenesis. The developing tumors recapitulate key features of the human disease. Mice were fed CDDO-Me (50 mg/kg diet), starting at 4 weeks of age. CDDO-Me significantly increased the age of mice at onset of first tumor (P < 0.001) by an average of 4.3 weeks and overall survival (P < 0.001) by 5.2 weeks. The drug also inhibited the infiltration of tumor-associated macrophages into mammary glands of PyMT mice at 12 weeks of age and reduced levels of the chemokines CXCL12 and CCL2 in primary PyMT mammary tumor cells. Treatment with this multifunctional drug also inhibited secretion of matrix metalloproteinase-9 in primary tumor cells from PyMT mice and decreased proliferation of these cells by inhibiting cyclin D1 and decreasing phosphorylation of epidermal growth factor receptor and STAT3.

Antiangiogenic activity of indole-3-carbinol in endothelial cells stimulated with activated macrophages

The effect of indole-3-carbinol (I3C), a major indolic metabolite in cruciferous vegetables, on lipopolysaccharide (LPS)-activated macrophage-induced tube formation and its associated factors in endothelial EA hy926 cells was investigated. LPS significantly enhanced the capillary-like structure of endothelial cells (ECs) co-cultured with macrophages, but no such effect was observed in single-cultured ECs. I3C, on the other hand, suppressed such enhancement in concert with decreased secretions of vascular endothelial growth factor (VEGF), nitric oxide (NO), interleukin-6 (IL-6), and matrix metalloproteinases (MMPs). The results obtained from cultivating ECs with conditioned medium (CM) collected from macrophages suggested that both ECs and macrophages were inactivated by I3C. These results indicate that I3C from cruciferous vegetables may possess potential roles in preventing inflammation-associated angiogenic diseases.

Prostaglandins in cancer cell adhesion, migration, and invasion

Prostaglandins exert a profound influence over the adhesive, migratory, and invasive behavior of cells during the development and progression of cancer. Cyclooxygenase-2 (COX-2) and microsomal prostaglandin E₂ synthase-1 (mPGES-1) are upregulated in inflammation and cancer. This results in the production of prostaglandin E₂ (PGE₂), which binds to and activates G-protein-coupled prostaglandin E_1–4 receptors (EP_1–4). Selectively targeting the COX-2/mPGES-1/PGE₂/EP_1–4 axis of the prostaglandin pathway can reduce the adhesion, migration, invasion, and angiogenesis. Once stimulated by prostaglandins, cadherin adhesive connections between epithelial or endothelial cells are lost. This enables cells to invade through the underlying basement membrane and extracellular matrix (ECM). Interactions with the ECM are mediated by cell surface integrins by “outside-in signaling” through Src and focal adhesion kinase (FAK) and/or “inside-out signaling” through talins and kindlins. Combining the use of COX-2/mPGES-1/PGE₂/EP_1–4 axis-targeted molecules with those targeting cell surface adhesion receptors or their downstream signaling molecules may enhance cancer therapy.

Inhibiting NF-κB in the developing lung disrupts angiogenesis and alveolarization

Bronchopulmonary dysplasia (BPD), a chronic lung disease of infancy, is characterized by arrested alveolar development. Pulmonary angiogenesis, mediated by the vascular endothelial growth factor (VEGF) pathway, is essential for alveolarization. However, the transcriptional regulators mediating pulmonary angiogenesis remain unknown. We previously demonstrated that NF-κB, a transcription factor traditionally associated with inflammation, plays a unique protective role in the neonatal lung. Therefore, we hypothesized that constitutive NF-κB activity is essential for postnatal lung development. Blocking NF-κB activity in 6-day-old neonatal mice induced the alveolar simplification similar to that observed in BPD and significantly reduced pulmonary capillary density. Studies to determine the mechanism responsible for this effect identified greater constitutive NF-κB in neonatal lung and in primary pulmonary endothelial cells (PEC) compared with adult. Moreover, inhibiting constitutive NF-κB activity in the neonatal PEC with either pharmacological inhibitors or RNA interference blocked PEC survival, decreased proliferation, and impaired in vitro angiogenesis. Finally, by chromatin immunoprecipitation, NF-κB was found to be a direct regulator of the angiogenic mediator, VEGF-receptor-2, in the neonatal pulmonary vasculature. Taken together, our data identify an entirely novel role for NF-κB in promoting physiological angiogenesis and alveolarization in the developing lung. Our data suggest that disruption of NF-κB signaling may contribute to the pathogenesis of BPD and that enhancement of NF-κB may represent a viable therapeutic strategy to promote lung growth and regeneration in pulmonary diseases marked by impaired angiogenesis.

Hemangiogenesis and lymphangiogenesis in corneal pathology

PURPOSE

We characterized the presence of hemangiogenesis (HA) and lymphangiogenesis (LA) in human corneal specimens exhibiting 13 underlying pathologies.

METHODS

Human corneal specimens were obtained from consenting subjects (n = 2 or n = 3 for each pathology; total sample size, n = 35). The pathological specimens were stained with hematoxylin and eosin (H&E) to determine the presence or absence of corneal neovascularization (NV) and superficial or deep stromal distribution of NV. Immunohistochemical staining was then performed to differentiate HA (positive for CD31) from LA (positive for lymphatic vessel endothelial hyaluronan receptor-1 [LYVE-1]).

RESULTS

The double-negative (CD31(-)/LYVE-1(-)) immunostaining, indicating the absence of NV, was exhibited by 21 specimens (60%). CD31(-)/LYVE-1(-), indicating the presence of HA and absence of LA, was exhibited by 12 specimens (34%). The double-positive (CD31(+)/LYVE-1(+)) phenotype, indicating both HA and LA, was exhibited by 2 specimens (6%). Notably, the CD31(-)/LYVE-1(-) phenotype, indicating the presence of LA and absence of HA, was not detected among the specimens. Deep stromal NV was exhibited in a 4:3 ratio to superficial stromal NV. The double-negative immunostaining was more prevalent in noninflammatory pathologies, particularly in comparison with combined neovascular phenotypes (ie, CD31(+) or LYVE-1(+)). Among the neovascular phenotypes, HA was 7 times more common than LA. Specimens exhibiting LA presented only with the double-positive phenotype.

CONCLUSIONS

HA is the predominant component of NV in corneal pathologies. LA accompanies HA; however, isolated LA (from lymphatics in the conjunctiva) does not occur in these corneal pathologies. Our results suggest the potential therapeutic utility of targeting antineovascular therapies specifically for corneal HA and/or LA pathology.

The mRNA expression of various angiogenesis-related genes in pediatric sarcomas and nonmalignant lesions of tissue

For better understanding cancer pathogenesis and searching a potential target for antineoplastic therapy, the authors have studied mRNA expression profile in tissues from 39 children with histological confirmed malignant sarcomas and from 23 patients with bone and soft tissue nonmalignant lesions. mRNA levels of Angiogenesis-related genes VEGFA (including isoforms of 121, 165, 189), VEGFC, VEGFR-1, VEGFR-2, VEGFR-3, HIF-1α, TF, TFPI-1, TFPI-2, uPA, PAI-1 in pediatric specimens were examined using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). uPA, HIF-1α, VEGFR-1, VEGFR-2, VEGFR-3, and VEGFC mRNA levels from nonmalignant tissue were significantly higher than those from cancer tissue. On the other hand, isoform VEGFA121 and VEGFA165 and ratio VEGFA165/189 mRNA levels in cancer were higher in comparison with nonmalignant tissue. There was a strong correlation between VEGFA165 and VEGFA189 mRNA expression levels both in cancer tissue and in nonmalignant tissue. In grade 4 tumors in comparison with grade 2 tumors, there was a reduced VEGFA165/189 ratio. Moreover, TFPI-1 and TFPI-2 mRNA levels were significantly lower in sarcomas than in nonmalignant lesions and TFPI-2 was significantly lower in grade 4 tumors than in grade 2. The present data suggested that mRNA overexpression of angiogenesis-related genes is not a prerogative of malignant tissues. The authors supposed that in pediatric bone and soft tissue pathology, high expression of mRNAs of some angiogenesis-related genes may be associated with inflammation and physiological angiogenesis rather than with the development of a malignant tumor. The authors showed the importance of VEGFA121 and/or VEGFA165 and VEGFA165/189 isoform ratio in pediatric sarcomas neoangiogenesis and TFPI-2 for tumors grade 4.

Neuropilin-1 is upregulated in Sjögren's syndrome and contributes to pathological neovascularization

Neuropilin-1 (NRP1) is a transmembrane co-receptor for members of the vascular endothelial growth factor family. Recent studies revealed an important role of NRP1 in angiogenesis and progression of many diseases. The role of NRP1 in the development of Sjögren's syndrome (SS), one of the most common rheumatic diseases, has not yet been investigated. Molecular studies and protein expression techniques were performed to elucidate the gene and protein expression profile of NRP1 in human salivary gland epithelial cells (SGEC) from primary SS. We used human microarrays and transient transfection with a mutant form of the negative inhibitory κBα proteins (IκBαDN) to investigate whether selective inhibition of nuclear Factor-κB (NF-κB) improves NRP1-mediated pro-angiogenic factors release from SS SGEC. The selective NRP1 function inhibition with an antibody to human NRP1, was employed to evaluate the therapeutic potential of targeting NRP1. We demonstrate that NRP1 is expressed in SGEC of both human healthy biopsies and in SS samples, and increased NRP1 expression in SS SGEC is significantly associated with pro-angiogenic factors release. Neutralizing anti-NRP1 antibody decreased pro-angiogenic factor production from SS SGEC and blocking NF-κB activation could be a way to inhibit NRP1-mediated angiogenesis in Sjögren's syndrome.

Differential gene expression from microarray analysis distinguishes woven and lamellar bone formation in the rat ulna following mechanical loading

Formation of woven and lamellar bone in the adult skeleton can be induced through mechanical loading. Although much is known about the morphological appearance and structural properties of the newly formed bone, the molecular responses to loading are still not well understood. The objective of our study was to use a microarray to distinguish the molecular responses between woven and lamellar bone formation induced through mechanical loading. Rat forelimb loading was completed in a single bout to induce the formation of woven bone (WBF loading) or lamellar bone (LBF loading). A set of normal (non-loaded) rats were used as controls. Microarrays were performed at three timepoints after loading: 1 hr, 1 day and 3 days. Confirmation of microarray results was done for a select group of genes using quantitative real-time PCR (qRT-PCR). The micorarray identified numerous genes and pathways that were differentially regulated for woven, but not lamellar bone formation. Few changes in gene expression were evident comparing lamellar bone formation to normal controls. A total of 395 genes were differentially expressed between formation of woven and lamellar bone 1 hr after loading, while 5883 and 5974 genes were differentially expressed on days 1 and 3, respectively. Results suggest that not only are the levels of expression different for each type of bone formation, but that distinct pathways are activated only for woven bone formation. A strong early inflammatory response preceded an increase in angiogenic and osteogenic gene expression for woven bone formation. Furthermore, at later timepoints there was evidence of bone resorption after WBF loading. In summary, the vast coverage of the microarray offers a comprehensive characterization of the early differences in expression between woven and lamellar bone formation.

Chitinase 3-like 1 promotes macrophage recruitment and angiogenesis in colorectal cancer

Chitinase 3-like 1 (CHI3L1), one of mammalian members of the chitinase family, is expressed in several types of human cancer, and elevated serum level of CHI3L1 is suggested to be a biomarker of poor prognosis in advanced cancer patients. However, the overall biological function of CHI3L1 in human cancers still remains unknown. Studies were performed to characterize the role of CHI3L1 in cancer pathophysiology utilizing human colorectal cancer samples and human cell lines. Plasma protein and tissue mRNA expression levels of CHI3L1 in colorectal cancer were strongly upregulated. Immunohistochemical analysis showed that CHI3L1 was expressed in cancer cells and CHI3L1 expression had a significant association with the number of infiltrated macrophages and microvessel density. By utilizing trans-well migration and tube formation assays, overexpression of CHI3L1 in SW480 cells (human colon cancer cells) enhanced the migration of THP-1 cells (human macrophage cells) and HUVECs (human endothelial cells), and the tube formation of HUVECs. The knockdown of CHI3L1 by RNA interference or the neutralization of CHI3L1 by anti-CHI3L1 antibody displayed strong suppression of CHI3L1-induced migration and tube formation. Cell proliferation assay showed that CHI3L1 overexpression significantly enhanced the proliferation of SW480 cells. ELISA analysis showed that CHI3L1 increased the secretion of inflammatory chemokines, IL-8 and MCP-1, from SW480 cells through mitogen-activated protein kinase (MAPK) signaling pathway. Both neutralization of IL-8 or MCP-1 and inhibition or knockdown of MAPK in SW480 cells significantly inhibited CHI3L1-induced migration and tube formation. In a xenograft mouse model, overexpression of CHI3L1 in HCT116 cells (human colon cancer cells) enhanced the tumor growth as well as macrophage infiltration and microvessel density. In conclusion, CHI3L1 expressed in colon cancer cells promotes cancer cell proliferation, macrophage recruitment and angiogenesis. Thus, the inhibition of CHI3L1 activity may be a novel therapeutic strategy for human colorectal cancer.

Inflammation associated with obesity: relationship with blood and bone marrow endothelial cells

The purpose of this study was to assess the inflammatory nature of obesity and its effect on blood and bone marrow endothelial cell populations. Obese patients (BMI ≥30) had significantly higher concentrations of the inflammatory marker C-reactive protein (CRP) (P = 0.03) and lower concentrations of the anti-inflammatory cytokine interleukin-10 (IL-10) (P = 0.05). This cytokine profile is consistent with obesity being an inflammatory condition and is further supported by the significant correlation between total white blood cell count and BMI (r = 0.15; P = 0.035). High BMI was associated with significantly lower numbers of early endothelial cells (CD45(-)/CD34(+)) in the bone marrow (r = -0.20; P = 0.0068). There was also a significant inverse correlation between BMI and a more mature endothelial cell phenotype (CD45(-)/31(+)) in the blood (r = -0.17; P = 0.02). In addition, there was a significant correlation between BMI- and endothelial-related cells of hematopoietic origin (CD133(+)/VEGFR-2(+)) in the bone marrow (r = -0.26; P = 0.0007). Patients with higher plasma IL-10 and insulin-like growth factor (IGF) concentrations had higher numbers of endothelial phenotypes in the bone marrow suggesting a protective effect of these anti-inflammatory cytokines. In conclusion, this work confirms the inflammatory nature of obesity and is the first to report that obesity is associated with reduced endothelial cell numbers in the bone marrow of humans. These effects of obesity may be a potential mechanism for impaired tissue repair in obese patients.

Regulation of inflammation in cancer by eicosanoids

Inflammation in the tumor microenvironment is now recognized as one of the hallmarks of cancer. Endogenously produced lipid autacoids, locally acting small molecule lipid mediators, play a central role in inflammation and tissue homeostasis, and have recently been implicated in cancer. A well-studied group of autacoid mediators that are the products of arachidonic acid metabolism include: the prostaglandins, leukotrienes, lipoxins and cytochrome P450 (CYP) derived bioactive products. These lipid mediators are collectively referred to as eicosanoids and are generated by distinct enzymatic systems initiated by cyclooxygenases (COX 1 and 2), lipoxygenases (5-LOX, 12-LOX, 15-LOXa, 15-LOXb), and cytochrome P450s, respectively. These pathways are the target of approved drugs for the treatment of inflammation, pain, asthma, allergies, and cardiovascular disorders. Beyond their potent anti-inflammatory and anti-cancer effects, non-steroidal anti-inflammatory drugs (NSAIDs) and COX-2 specific inhibitors have been evaluated in both preclinical tumor models and clinical trials. Eicosanoid biosynthesis and actions can also be directly influenced by nutrients in the diet, as evidenced by the emerging role of omega-3 fatty acids in cancer prevention and treatment. Most research dedicated to using eicosanoids to inhibit tumor-associated inflammation has focused on the COX and LOX pathways. Novel experimental approaches that demonstrate the anti-tumor effects of inhibiting cancer-associated inflammation currently include: eicosanoid receptor antagonism, overexpression of eicosanoid metabolizing enzymes, and the use of endogenous anti-inflammatory lipid mediators. Here we review the actions of eicosanoids on inflammation in the context of tumorigenesis. Eicosanoids may represent a missing link between inflammation and cancer and thus could serve as therapeutic target(s) for inhibiting tumor growth.

The antitumor effect of a novel angiogenesis inhibitor (an octahydronaphthalene derivative) targeting both VEGF receptor and NF-κB pathway

Development of a novel type of angiogenesis inhibitor will be essential for further improvement of therapeutics against cancer patients. We examined whether an octahydronaphthalene derivative, AMF-26, which was screened as an inhibitor of intercellular adhesion molecule-1 (ICAM-1) production stimulated by inflammatory stimuli in vascular endothelial cells, could block angiogenesis in response to vascular endothelial growth factor (VEGF) and/or inflammatory cytokines. Low dose AMF-26 effectively inhibited the tumor necrosis factor-α (TNF-α)- or the interleukin-1β (IL-1β)-induced production of ICAM-1 in human umbilical vascular endothelial cells (HUVECs). We found that the TNF-α-induced phosphorylation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) and nuclear translocation of p65 were impaired by AMF-26 in both endothelial cells and cancer cells. AMF-26 was found to inhibit the phosphorylation of VEGF receptor 1 (VEGFR1), VEGFR2 and the downstream signaling molecules Akt, extracellular signal-regulated kinase (ERK)1/2 stimulated by VEGF in HUVECs. Therefore, the VEGF-induced proliferation, migration and tube formation of vascular endothelial cells was highly susceptible to inhibition by AMF-26. Oral administration of AMF-26 significantly blocked VEGF- or IL-1β-induced angiogenesis in the mouse cornea, and also tumor angiogenesis and growth. Together, our results indicate that AMF-26 inhibits angiogenesis through suppression of both VEGFR1/2 and nuclear factor-κB (NF-κB) signaling pathways when stimulated by VEGF or inflammatory cytokines. AMF-26 could be a promising novel candidate drug for cancer treatments.

Quercetin's effects on intestinal polyp multiplicity and macrophage number in the Apc(Min/+) mouse

Numerous in vitro studies argue for quercetin's chemopreventive potential in colon cancer; however, experimental studies in rodents are limited. Macrophages play a role in tumorigenesis, but the effects of quercetin on macrophage infiltration in colon cancer is unknown. We examined the effects of quercetin on intestinal polyp multiplicity and macrophage number in Apc(Min/+) mice. Apc(Min/+) mice were assigned to placebo or quercetin (n = 8/group) groups. Mice were given a placebo or quercetin (0.02%) diet from 4-20 wk of age, after which intestines were analyzed for polyp number and size in the small intestine (Sections 1-4) and colon (Section 5) and for macrophage number in the small intestine (Sections 1 and 3). Spleen weight was determined as a marker of systemic inflammation. Quercetin decreased total intestinal polyps by 67% (P < 0.05). Specifically, quercetin reduced intestinal polyps in categories >2 mm (69%) and 1-2 mm (79%; P < 0.05), and in Sections 2 (75%), 3 (80%), and 4 (79%; P < 0.05). Quercetin also decreased macrophage number in Sections 1 (57%) and 3 (81%), and spleen weight (P < 0.05). These data suggest that quercetin can reduce polyp number and size distribution in the Apc(Min/+) mouse and that these effects may be related to a reduction in macrophage infiltration.

Resveratrol, MicroRNAs, Inflammation, and Cancer

MicroRNAs are short noncoding RNAs that regulate the expression of many target genes posttranscriptionally and are thus implicated in a wide array of cellular and developmental processes. The expression of miR-155 or miR-21 is upregulated during the course of the inflammatory response, but these microRNAs are also considered oncogenes due to their upregulation of expression in several types of tumors. Furthermore, it is now well established that inflammation is associated with the induction or the aggravation of nearly 25% of cancers. Therefore, the above microRNAs are thought to link inflammation and cancer. Recently, resveratrol (trans-3,4′,5-trihydroxystilbene), a natural polyphenol with antioxidant, anti-inflammatory, and anticancer properties, currently at the stage of preclinical studies for human cancer prevention, has been shown to induce the expression of miR-663, a tumor-suppressor and anti-inflammatory microRNA, while downregulating miR-155 and miR-21. In this paper we will discuss how the use of resveratrol in therapeutics may benefit from the preanalyses on the status of expression of miR-155 or miR-21 as well as of TGFβ1. In addition, we will discuss how resveratrol activity might possibly be enhanced by simultaneously manipulating the levels of its key target microRNAs, such as miR-663.

Toll-like receptor 4 signaling integrates intestinal inflammation with tumorigenesis: lessons from the murine model of colitis-associated cancer

Chronic inflammation has long been implicated as a predisposition for cancer, but the underlying mechanism for how this occurs has remained obscure. Ulcerative colitis (UC) is a chronic inflammatory disorder of the large intestine which is known to be highly linked to colorectal cancer. During chronic inflammation the intestinal mucosa is in a constant cycle of injury and repair resulting in aberrant epithelial proliferation, a process that increases the risk of neoplastic transformation. In particular, the coexistence of commensal flora in the intestine plays an important role in the regulation of mucosal restitution after epithelial injury. It has become apparent that signaling through toll-like receptors (TLRs), the receptor family recognizing pathogen-associated molecular patterns, is crucial to intestinal epithelial proliferation and mucosal restitution. We have recently described two important downstream pathways underlying TLR4-mediated epithelial proliferation in a mouse model of colitis-associated cancer; i.e., cyclooxygenase 2 (COX-2)-mediated production of prostaglandin E₂ (PGE₂), and induction of specific ligands for epidermal growth factor receptor (EGFR). These two pathways are closely involved with mucosal levels of PGE₂ and other prostanoids such as 15-deoxy-delta 12,14-prostaglandin-J2 (15d-PGJ2). Understanding the fine interplay between the TLR signaling and intestinal tumorigenesis in the setting of chronic inflammation can contribute to establishing a novel treatment strategy for inflammation-associated cancers.

Macrophage infiltration predicts a poor prognosis for human ewing sarcoma

Ewing sarcoma-primitive neuroectodermal tumor (EWS) is associated with the most unfavorable prognosis of all primary musculoskeletal tumors. The objective of the present study was to investigate whether tumor-associated macrophages (TAMs) affect the development of EWS. TAMs were isolated from mouse xenografts using CD11b magnetic beads and examined for their cytokine expression and osteoclastic differentiation. To evaluate the role of TAMs in xenograft formation, liposome-encapsulated clodronate was used to deplete TAMs in mice. Macrophage infiltration and tumor microvascular density were histologically evaluated in 41 patients with EWS, and association with prognosis was examined using Kaplan-Meier survival analysis. In mouse EWS xenografts, TAMs expressed higher concentrations of cytokines including interleukin-6, keratinocyte-derived chemokine, and monocyte chemotactic protein-1. TAMs were more capable than normal monocytes of differentiating into tartrate-resistant acid phosphatase-positive giant cells. Depleting macrophages using liposome-encapsulated clodronate significantly inhibited development of EWS xenografts. In human EWS samples, higher levels of CD68-positive macrophages were associated with poorer overall survival. In addition, enhanced vascularity, increase in the amount of C-reactive protein, and higher white blood cell counts were also associated with poor prognosis and macrophage infiltration. TAMs seem to enhance the progression of EWS by stimulating both angiogenesis and osteoclastogenesis. Further investigation of the behavior of TAMs may lead to development of biologically targeted therapies for EWS.