CXCL1 induced by prostaglandin E2 promotes angiogenesis in colorectal cancer

Hypoxia and prostaglandin E receptor 4 signalling pathways synergise to promote endometrial adenocarcinoma cell proliferation and tumour growth

The prostaglandin endoperoxide synthase (PTGS) pathway is a potent driver of tumour development in humans by enhancing the biosynthesis and signalling of prostaglandin (PG) E(2). PTGS2 expression and PGE(2) biosynthesis is elevated in endometrial adenocarcinoma, however the mechanism whereby PTGS and PGE(2) regulate endometrial tumour growth is unknown. Here we investigated (a) the expression profile of the PGE synthase enzymes (PTGES, PTGES-2, PTGES-3) and PGE receptors (PTGER1-4) in endometrial adenocarcinomas compared with normal endometrium and (b) the role of PTGER4 in endometrial tumorigenesis in vivo. We found elevated expression of PTGES2 and PTGER4 and suppression of PTGER1 and PTGER3 in endometrial adenocarcinomas compared with normal endometrium. Using WT Ishikawa endometrial adenocarcinoma cells and Ishikawa cells stably transfected with the full length PTGER4 cDNA (PTGER4 cells) xenografted in the dorsal flanks of nude mice, we show that PTGER4 rapidly and significantly enhances tumour growth rate. Coincident with enhanced PTGER4-mediated tumour growth we found elevated expression of PTGS2 in PTGER4 xenografts compared with WT xenografts. Furthermore we found that the augmented growth rate of the PTGER4 xenografts was not due to enhanced angiogenesis, but regulated by an increased proliferation index and hypoxia. In vitro, we found that PGE(2) and hypoxia independently induce expression of PTGER4 indicating two independent pathways regulating prostanoid receptor expression. Finally we have shown that PGE(2) and hypoxia synergise to promote cellular proliferation of endometrial adenocarcinoma cells.

Widespread hypomethylation occurs early and synergizes with gene amplification during esophageal carcinogenesis

Although a combination of genomic and epigenetic alterations are implicated in the multistep transformation of normal squamous esophageal epithelium to Barrett esophagus, dysplasia, and adenocarcinoma, the combinatorial effect of these changes is unknown. By integrating genome-wide DNA methylation, copy number, and transcriptomic datasets obtained from endoscopic biopsies of neoplastic progression within the same individual, we are uniquely able to define the molecular events associated progression of Barrett esophagus. We find that the previously reported global hypomethylation phenomenon in cancer has its origins at the earliest stages of epithelial carcinogenesis. Promoter hypomethylation synergizes with gene amplification and leads to significant upregulation of a chr4q21 chemokine cluster and other transcripts during Barrett neoplasia. In contrast, gene-specific hypermethylation is observed at a restricted number of loci and, in combination with hemi-allelic deletions, leads to downregulatation of selected transcripts during multistep progression. We also observe that epigenetic regulation during epithelial carcinogenesis is not restricted to traditionally defined “CpG islands,” but may also occur through a mechanism of differential methylation outside of these regions. Finally, validation of novel upregulated targets (CXCL1 and 3, GATA6, and DMBT1) in a larger independent panel of samples confirms the utility of integrative analysis in cancer biomarker discovery.

The incidence of esophageal adenocarcinoma (EA) is increasing at an alarming pace in the United States. Distinct pathological stages of Barrett's metaplasia and low- and high-grade dysplasia can be seen preceding malignant transformation. These precursor lesions provide a unique in vivo model for deepening our understanding the early steps in human neoplasia. By integrating genome-wide DNA methylation, copy number, and transcriptomic datasets obtained from endoscopic biopsies of neoplastic progression within the same individual, we are uniquely able to define the molecular events associated progression of Barrett esophagus. We show that the predominant change during this process is loss of DNA methylation. We show that this global hypomethylation occurs very early during the process and is seen even in preinvasive lesions. This loss of DNA methylation drives carcinogenesis by cooperating with gene amplifications in upregulating proteins during this process. Finally we uncovered proteins that upregulated by loss of methylation or gene amplification (CXCL1 and 3, GATA6, and DMBT1) and show their relevance by validating their levels in larger independent panel of samples, thus confirming the utility of integrative analysis in cancer biomarker discovery.

A tunable dual-promoter integrator for targeting of cancer cells

Precise discrimination between similar cellular states is essential for autonomous decision-making scenarios, such as in vivo targeting of diseased cells. Discrimination could be achieved by delivering an effector gene expressed under a highly active context-specific promoter. Yet, a single-promoter approach has linear response and offers limited control of specificity and efficacy. Here, we constructed a dual-promoter integrator, which expresses an effector gene only when the combined activity of two internal input promoters is high. A tunable response provides flexibility in choosing promoter inputs and effector gene output. Experiments using one premalignant and four cancer cell lines, over a wide range of promoter activities, revealed a digital-like response of input amplification following a sharp activation threshold. The response function is cell dependent with its overall magnitude increasing with degree of malignancy. The tunable digital-like response provides robustness, acts to remove input noise minimizing false-positive identification of cell states, and improves targeting precision and efficacy.

Analysis of normal-tumour tissue interaction in tumours: prediction of prostate cancer features from the molecular profile of adjacent normal cells

Statistical modelling, in combination with genome-wide expression profiling techniques, has demonstrated that the molecular state of the tumour is sufficient to infer its pathological state. These studies have been extremely important in diagnostics and have contributed to improving our understanding of tumour biology. However, their importance in in-depth understanding of cancer patho-physiology may be limited since they do not explicitly take into consideration the fundamental role of the tissue microenvironment in specifying tumour physiology. Because of the importance of normal cells in shaping the tissue microenvironment we formulate the hypothesis that molecular components of the profile of normal epithelial cells adjacent the tumour are predictive of tumour physiology. We addressed this hypothesis by developing statistical models that link gene expression profiles representing the molecular state of adjacent normal epithelial cells to tumour features in prostate cancer. Furthermore, network analysis showed that predictive genes are linked to the activity of important secreted factors, which have the potential to influence tumor biology, such as IL1, IGF1, PDGF BB, AGT, and TGFβ.

The expression and prognostic impact of CXC-chemokines in stage II and III colorectal cancer epithelial and stromal tissue

Background:

The CXC-chemokine expression is linked with colorectal cancer (CRC) progression but their significance in resected CRC is unclear. We explored the prognostic impact of such expression in stage II and III CRC.

Methods:

Tissue microarrays were constructed from stage II and III CRC biopsies (n=254), and the expression of CXCL1 and CXCL8, and their receptors CXCR1 and CXCR2, in malignant and adjacent normal tissue was graded by immunohistochemistry and was correlated with prognostic factors.

Results:

Expression of CXCL1, CXCR1 and CXCR2 was elevated in tumour epithelium relative to normal adjacent tissue (P<0.001). CXCL8 expression was detectable in the peritumoural inflammatory infiltrate. There was no overall association between CXCL1, CXCR1 or CXCR2 expression and prognostic endpoints; however, univariate subgroup survival analysis demonstrated an inverse association between CXCL1 and recurrence-free survival (RFS) in stage III patients (P=0.041). The CXCL8 positivity in the tumour infiltrate, however, correlated with earlier disease stage (P<0.001) and improved relapse-free survival across the cohort (P<0.001). Disease stage (P<0.001) and tumour infiltrate CXCL8 positivity (P=0.007) were associated with enhanced RFS in multivariate Cox regression analysis.

Conclusion:

Autocrine CXC-chemokine signalling may have adverse prognostic effects in early CRC. Conversely, CXCL8 positivity within the immune infiltrate may have good prognostic significance.

Custom design of a GeXP multiplexed assay used to assess expression profiles of inflammatory gene targets in normal colon, polyp, and tumor tissue

Colon cancers are characterized by aberrant gene expression signatures associated with disease initiation and progression. Identification of aberrant gene expression associated with colon carcinogenesis has increased significantly with application of gene array technologies. Downstream processing of these data has been hindered by the lack of robust multiplexed gene quantitative technologies facilitating study of the identified multiple gene targets. The GenomeLab Genetic Analysis System presents a novel technology platform for quantitative multiplexed gene expression analysis. This report describes the custom design of a GeXP multiplexed assay used to assess expression profiles of 14 inflammatory gene targets in normal, polyp, and tumor tissue. Characteristic normal, polyp, and tumor tissue gene expression profiles were obtained. Statistical analysis confirmed comparable relative quantitation of gene expression using the GeXP, macroarray, and single-plex real-time polymerase chain reaction assays. GeXP assays may be usefully applied in clinical and regulatory studies of multiple gene targets. This system permits custom-design options for relative quantification of multiple gene target expression, simultaneously in a single reaction, using nanogram quantities of total RNA template. The system provides an approach to advance the study of multiple targets identified from gene array analysis with potential for characterizing gene expression signatures in clinical diagnostics.

Increased expression and activity of 12-lipoxygenase in oxygen-induced ischemic retinopathy and proliferative diabetic retinopathy: implications in retinal neovascularization

OBJECTIVE

Arachidonic acid is metabolized by 12-lipoxygenase (12-LOX) to 12-hydroxyeicosatetraenoic acid (12-HETE) and has an important role in the regulation of angiogenesis and endothelial cell proliferation and migration. The goal of this study was to investigate whether 12-LOX plays a role in retinal neovascularization (NV).

RESEARCH DESIGN AND METHODS

Experiments were performed using retinas from a murine model of oxygen-induced ischemic retinopathy (OIR) that was treated with and without the LOX pathway inhibitor, baicalein, or lacking 12-LOX. We also analyzed vitreous samples from patients with and without proliferative diabetic retinopathy (PDR). Western blotting and RT-PCR were used to assess the expression of 12-LOX, vascular endothelial growth factor (VEGF), and pigment epithelium-derived factor (PEDF). Liquid chromatography-mass spectrometry was used to assess the amounts of HETEs in the murine retina and human vitreous samples. The effects of 12-HETE on VEGF and PEDF expression were evaluated in Müller cells (rMCs), primary mouse retinal pigment epithelial cells, and astrocytes.

RESULTS

Retinal NV during OIR was associated with increased 12-LOX expression and 12-, 15-, and 5-HETE production. The amounts of HETEs also were significantly higher in the vitreous of diabetic patients with PDR. Retinal NV was markedly abrogated in mice treated with baicalein or mice lacking 12-LOX. This was associated with decreased VEGF expression and restoration of PEDF levels. PEDF expression was reduced in 12-HETE-treated rMCs, astrocytes, and the retinal pigment epithelium. Only rMCs and astrocytes showed increased VEGF expression by 12-HETE.

CONCLUSIONS

12-LOX and its product HETE are important regulators of retinal NV through modulation of VEGF and PEDF expression and could provide a new therapeutic target to prevent and treat ischemic retinopathy.

Animal models of colitis-associated carcinogenesis

Inflammatory bowel disease (IBD) is a group of chronic inflammatory disorders that affect individuals throughout life. Although the etiology and pathogenesis of IBD are largely unknown, studies with animal models of colitis indicate that dysregulation of host/microbial interactions are requisite for the development of IBD. Patients with long-standing IBD have an increased risk for developing colitis-associated cancer (CAC), especially 10 years after the initial diagnosis of colitis, although the absolute number of CAC cases is relatively small. The cancer risk seems to be not directly related to disease activity, but is related to disease duration/extent, complication of primary sclerosing cholangitis, and family history of colon cancer. In particular, high levels and continuous production of inflammatory mediators, including cytokines and chemokines, by colonic epithelial cells (CECs) and immune cells in lamina propria may be strongly associated with the pathogenesis of CAC. In this article, we have summarized animal models of CAC and have reviewed the cellular and molecular mechanisms underlining the development of carcinogenic changes in CECs secondary to the chronic inflammatory conditions in the intestine. It may provide us some clues in developing a new class of therapeutic agents for the treatment of IBD and CAC in the near future.

S100A8/A9 activate key genes and pathways in colon tumor progression

The tumor microenvironment plays an important role in modulating tumor progression. Earlier, we showed that S100A8/A9 proteins secreted by myeloid-derived suppressor cells (MDSC) present within tumors and metastatic sites promote an autocrine pathway for accumulation of MDSC. In a mouse model of colitis-associated colon cancer, we also showed that S100A8/A9-positive cells accumulate in all regions of dysplasia and adenoma. Here we present evidence that S100A8/A9 interact with RAGE and carboxylated glycans on colon tumor cells and promote activation of MAPK and NF-κB signaling pathways. Comparison of gene expression profiles of S100A8/A9-activated colon tumor cells versus unactivated cells led us to identify a small cohort of genes upregulated in activated cells, including Cxcl1, Ccl5 and Ccl7, Slc39a10, Lcn2, Zc3h12a, Enpp2, and other genes, whose products promote leukocyte recruitment, angiogenesis, tumor migration, wound healing, and formation of premetastatic niches in distal metastatic organs. Consistent with this observation, in murine colon tumor models we found that chemokines were upregulated in tumors, and elevated in sera of tumor-bearing wild-type mice. Mice lacking S100A9 showed significantly reduced tumor incidence, growth and metastasis, reduced chemokine levels, and reduced infiltration of CD11b(+)Gr1(+) cells within tumors and premetastatic organs. Studies using bone marrow chimeric mice revealed that S100A8/A9 expression on myeloid cells is essential for development of colon tumors. Our results thus reveal a novel role for myeloid-derived S100A8/A9 in activating specific downstream genes associated with tumorigenesis and in promoting tumor growth and metastasis.

The inflammatory microenvironment in colorectal neoplasia

Colorectal cancer (CRC) is a major cause of mortality and morbidity worldwide. Inflammatory activity within the stroma of invasive colorectal tumours is known to be a key predictor of disease activity with type, density and location of immune cells impacting on patient prognosis. To date, there has been no report of inflammatory phenotype within pre-malignant human colonic adenomas. Assessing the stromal microenvironment and particularly, inflammatory activity within colorectal neoplastic lesions is central to understanding early colorectal carcinogenesis. Inflammatory cell infiltrate was assessed by immunohistochemistry in paired colonic adenoma and adjacent normal colonic mucosa samples, and adenomas exhibiting increasing degrees of epithelial cell dysplasia. Macrophage phenotype was assessed using double stain immunohistochemistry incorporating expression of an intracellular enzyme of function. A targeted array of inflammatory cytokine and receptor genes, validated by RT-PCR, was used to assess inflammatory gene expression. Inflammatory cell infiltrates are a key feature of sporadic adenomatous colonic polyps with increased macrophage, neutrophil and T cell (specifically helper and activated subsets) infiltration in adenomatous colonic polyps, that increases in association with characteristics of high malignant potential, namely, increasing degree of cell dysplasia and adenoma size. Macrophages within adenomas express iNOS, suggestive of a pro-inflammatory phenotype. Several inflammatory cytokine genes (CXCL1, CXCL2, CXCL3, CCL20, IL8, CCL23, CCL19, CCL21, CCL5) are dysregulated in adenomas. This study has provided evidence of increased inflammation within pre-malignant colonic adenomas. This may allow potential mechanistic pathways in the initiation and promotion of early colorectal carcinogenesis to be identified.

The induction of S100p expression by the Prostaglandin E₂ (PGE₂)/EP4 receptor signaling pathway in colon cancer cells

BACKGROUND

Prostaglandin E₂ (PGE₂) levels are frequently elevated in colorectal carcinomas. PGE₂ is perceived via four transmembrane G protein coupled receptors (EP1-4), among which the EP4 receptor is most relevant. PGE₂/EP4-receptor interaction activates CREB via the ERK/MEK pathway. However, the downstream target genes activated by this pathway remained to be investigated.

METHODOLOGY/PRINICIPAL FINDINGS

Here, we have identified S100P (an EF-hand calcium binding protein) as a novel downstream target. We show by realtime RT-PCR that S100P mRNA levels are elevated in 14/17 (82%) colon tumor tissues as compared to paired adjacent normal colonic tissues. S100P expression is stimulated in the presence of PGE₂ in a time dependent manner at mRNA and protein levels in colon, breast and pancreatic cancer cells. Pharmacological and RNAi-mediated inhibition of the EP4 receptor attenuates PGE₂-dependent S100P mRNA induction. RNA(i)-mediated knockdown of CREB inhibits endogenous S100P expression. Furthermore, using luciferase reporter analysis and EMSA we show that mutation and/or deletion of the CRE sequence within the S100P promoter abolished PGE₂-mediated transcriptional induction. Finally, we demonstrate that RNA(i)-mediated knockdown of S100P compromised invadopodia formation, colony growth and motility of colon cancer cells. Interestingly, endogenous knock down of S100P decreases ERK expression levels, suggesting a role for ERK in regulating S100P mediated cell growth and motility.

CONCLUSIONS/SIGNIFICANCE

Together, our findings show for the first time that S100P expression is regulated by PGE₂/EP4-receptor signaling and may participate in a feedback signaling that perpetuates tumor cell growth and migration. Therefore, our data suggest that dysregulated S100P expression resulting from aberrant PGE₂/EP4 receptor signaling may have important consequences relevant to colon cancer pathogenesis.

Chemokines as mediators of tumor angiogenesis and neovascularization

Chemokines are a superfamily of structurally homologous heparin-binding proteins that influence tumor growth and metastasis. Several members of the CXC and CC chemokine families are potent inducers of neovascularization, whereas a subset of the CXC chemokines are potent inhibitors. In this paper, we review the current literature regarding the role of chemokines as mediators of tumor angiogenesis and neovascularization.

p53 status in stromal fibroblasts modulates tumor growth in an SDF1-dependent manner

The p53 tumor suppressor exerts a variety of cell-autonomous effects that are aimed to thwart tumor development. In addition, however, there is growing evidence for cell nonautonomous tumor suppressor effects of p53. In the present study, we investigated the impact of stromal p53 on tumor growth. Specifically, we found that ablation of p53 in fibroblasts enabled them to promote more efficiently the growth of tumors initiated by PC3 prostate cancer-derived cells. This stimulatory effect was dependent on the increased expression of the chemokine SDF-1 in the p53-deficient fibroblasts. Notably, fibroblasts harboring mutant p53 protein were more effective than p53-null fibroblasts in promoting tumor growth. The presence of either p53-null or p53-mutant fibroblasts led also to a markedly elevated rate of metastatic spread of the PC3 tumors. These findings implicate p53 in a cell nonautonomous tumor suppressor role within stromal fibroblasts, through suppressing the production of tumor stimulatory factors by these cells. Moreover, expression of mutant p53 by tumor stroma fibroblasts might exert a gain of function effect, further accelerating tumor development.

Chemokine growth-regulated oncogene 1 as a putative biomarker for gastric cancer progression

Gastric cancer (GC) is a heterogeneous disease that is not well detected by current tumor markers. Identifying molecular markers that can predict the potential for tumor progression is important for appropriate individualized therapy. Using the Cancer Metastasis Research Center microarray database (17K cDNA microarray), we identified genes that were differentially expressed between 96 cancer and 98 normal gastric tissues using significant analysis of microarrays. From these, we selected genes that were overexpressed more than twofold in tumor tissues that encode secreted proteins. The selected genes were validated with ELISA using the sera of 96 GC patients and 48 healthy donors. Our first round of selection included 6510 genes that were differentially expressed between 96 cancer and 98 normal gastric tissues with a minimal false discovery rate of 0.005%. Out of those genes, we picked 386 that encoded secreted proteins based on the SOURCE database. Of these genes, we focused on 55 that were overexpressed more than twofold in GC compared to normal tissues. With Ingenuity Pathway Analysis, we found 34 genes related to cancer. One in particular, chemokine growth-regulated oncogene 1, CXCL1, has been linked to cancer progression in various cancer types, but not yet to GC. Levels of CXCL1 in serum samples of GC patients were significantly higher compared with healthy donors (P < 0.05). Within GC patients, CXCL1 serum levels increased according to tumor stage and lymph node metastasis. The CXCL1 gene appears to be a candidate marker for GC progression.

Tumour infiltrating host cells and their significance for hyperthermia

Much information can be gained by investigating the consequences of hyperthermia on individual cell populations in vitro, however the precise effects of such a therapeutic modality in vivo depend on the tumour microenvironment and the cellular composition therein. Although the direct cytotoxic effects of hyperthermia on tumour tissue can lead to an immediate reduction in tumour volume, long-term benefits to local and distal tumour recurrence will very much depend on the induction of immunity and the capacity of effector cells to traffic to tumours and elicit their cytotoxic functions. The immunological sequelae to hyperthermia are even more important in those instances when large tumour volumes preclude the delivery of appropriate thermal damage. The development of protective anti-tumour immunity requires a plethora of interactions and responses, the vast majority of which can be influenced by temperatures that are consistent with fever-like temperatures (39 degrees -40 degrees C), as well as hyperthermia treatment (<41 degrees C). This article reviews current knowledge relating to the effects of hyperthermia treatment on aspects of the induction and manifestation of immunological responses that are most pertinent to the development and maintenance of protective anti-tumour immunity.

CXC chemokines in cancer angiogenesis and metastases

The tumor microenvironment is extremely complex that depends on tumor cell interaction with the responding host cells. Angiogenesis, or new blood vessel growth from preexisting vasculature, is a preeminent feature of successful tumor growth of all solid tumors. While a number of factors produced by both the tumor cells and host responding cells have been discovered that regulate angiogenesis, increasing evidence is growing to support the important role of CXC chemokines in this process. As a family of cytokines, the CXC chemokines are pleiotropic in their ability to regulate tumor-associated angiogenesis, as well as cancer cell metastases. In this chapter, we will discuss the disparate activity that CXC chemokines play in regulating cancer-associated angiogenesis and metastases.

Ciglitazone negatively regulates CXCL1 signaling through MITF to suppress melanoma growth

We have previously demonstrated that the thiazolidinedione ciglitazone inhibited, independently of PPARγ activation, melanoma cell growth. Further investigations now show that ciglitazone effects are mediated through the regulation of secreted factors. Q-PCR screening of several genes involved in melanoma biology reveals that ciglitazone inhibits expression of the CXCL1 chemokine gene. CXCL1 is overexpressed in melanoma and contributes to tumorigenicity. We show that ciglitazone induces a diminution of CXCL1 level in different human melanoma cell lines. This effect is mediated by the downregulation of microphthalmia-associated transcription factor, MITF, the master gene in melanocyte differentiation and involved in melanoma development. Further, recombinant CXCL1 protein is sufficient to abrogate thiazolidinedione effects such as apoptosis induction, whereas extinction of the CXCL1 pathway mimics phenotypic changes observed in response to ciglitazone. Finally, inhibition of human melanoma tumor development in nude mice treated with ciglitazone is associated with a strong decrease in MITF and CXCL1 levels. Our results show that anti-melanoma effects of thiazolidinediones involve an inhibition of the MITF/CXCL1 axis and highlight the key role of this specific pathway in melanoma malignancy.

Potent angiogenesis inhibition by the particulate form of fullerene derivatives

Antiangiogenesis is an effective strategy for cancer treatment because uncontrolled tumor growth depends on tumor angiogenesis and sufficient blood supply. Great progress has been made in developing a "molecular" form of angiogenesis inhibitors; however, the narrow inhibition spectrum limits anticancer efficacy as those inhibitors that usually target a few or even a single angiogenic factor among many angiogenic factors might initially be effective but ultimately lead to the failure of the treatment due to the induction of expression of other angiogenic factors. In this work, we report that with a multiple hydroxyl groups functionalized surface, the Gd@C(82)(OH)(22) fullerenic nanoparticles (f-NPs) are capable of simultaneously downregulating more than 10 angiogenic factors in the mRNA level that is further confirmed at the protein level. After studying this antiangiogenesis activity of the f-NPs by cellular experiment, we further investigated its anticancer efficacy in vivo. A two-week treatment with the f-NPs decreased >40% tumor microvessels density and efficiently lowered the speed of blood supply to tumor tissues by approximately 40%. Efficacy of the treatment using f-NPs in nude mice was comparable to the clinic anticancer drug paclitaxel, while no pronounced side effects were found. These findings indicate that the f-NPs with multiple hydroxyl groups serve as a potent antiangiogenesis inhibitor that can simultaneously target multiple angiogenic factors. We propose that using nanoscale "particulate" itself as a new form of medicine (particulate medicine) may be superior to the traditional "molecular" form of medicine (molecular medicine) in cancer treatment.

Molecular pathways and targets in cancer-related inflammation

Selected inflammatory conditions increase the risk of cancer. An inflammatory component is present also in the micro-environment of tumours epidemiologically unrelated to inflammation. An intrinsic (driven by genetic events that cause neoplasia) and an extrinsic (driven by inflammatory conditions which predispose to cancer) pathway link inflammation and cancer. Smouldering inflammation in the tumour microenvironment contributes to proliferation and survival of malignant cells, angiogenesis, metastasis, subversion of adaptive immunity, response to hormones, and chemotherapeutic agents. Emerging evidence also suggests that cancer-related inflammation promotes genetic instability. Thus, cancer-related inflammation represents a target for innovative diagnostic and therapeutic strategies.

Prostate cancer immunotherapy yields superior long-term survival in TRAMP mice when administered at an early stage of carcinogenesis prior to the establishment of tumor-associated immunosuppression at later stages

Prostate cancer immunotherapy clinical trials have been performed, but often in immunocompromised patients with limited clinical success. The study aim was to determine whether the stage of prostate cancer development at which immunization occurs affects vaccine efficacy, and if so which tumor-associated immunosuppressive mechanisms may be involved at later stages. Therapeutic vaccination of TRAMP mice with only precancerous PIN lesions confered superior protection to immunization after development of invasive carcinoma. The presence of Treg, upregulation of tumor indoleamine-2,3-dioxygenase and TGFbeta and an immunosuppressive intratumoral cytokine milieu were identified in more advanced prostate cancer. These results indicate that prostate cancer immunotherapy trials will be more successful if conducted in patients with less advanced disease.

The tumor microenvironment in colorectal carcinogenesis

Colorectal cancer is the second leading cause of cancer-related mortality in the United States. Therapeutic developments in the past decade have extended life expectancy in patients with metastatic disease. However, metastatic colorectal cancers remain incurable. Numerous agents that were demonstrated to have significant antitumor activity in experimental models translated into disappointing results in extending patient survival. This has resulted in more attention being focused on the contribution of tumor microenvironment to the progression of a number of solid tumors including colorectal cancer. A more complete understanding of interactions between tumor epithelial cells and their stromal elements will enhance therapeutic options and improve clinical outcome. Here we will review the role of various stromal components in colorectal carcinogenesis and discuss the potential of targeting these components for the development of future therapeutic agents.

Eicosanoids and cancer

Eicosanoids, including prostaglandins and leukotrienes, are biologically active lipids that have been implicated in various pathological processes, such as inflammation and cancer. This Review highlights our understanding of the intricate roles of eicosanoids in epithelial-derived tumours and their microenvironment. The knowledge of how these lipids orchestrate the complex interactions between transformed epithelial cells and the surrounding stromal cells is crucial for understanding tumour evolution, progression and metastasis. Understanding the molecular mechanisms underlying the role of prostaglandins and other eicosanoids in cancer progression will help to develop more effective cancer chemopreventive and/or therapeutic agents.

Chemokines and chemokine receptors: new insights into cancer-related inflammation

Chemokines are involved in cellular interactions and tropism in situations frequently associated with inflammation. Recently, the importance of chemokines and chemokine receptors in inflammation associated with carcinogenesis has been highlighted. Increasing evidence suggests that chemokines are produced by tumor cells as well as by cells of the tumor microenvironment including cancer-associated fibroblasts (CAFs), mesenchymal stem cells (MSCs), endothelial cells, tumor-associated macrophages (TAMs) and more recently tumor-associated neutrophils (TANs). In addition to affecting tumor cell proliferation, angiogenesis and metastasis, chemokines also seem to modulate senescence and cell survival. Here, we review recent progress on the roles of chemokines and chemokine receptors in cancer-related inflammation, and discuss the mechanisms underlying chemokine action in cancer that might facilitate the development of novel therapies in the future.

Hypertonic environment elicits cyclooxygenase-2-driven prostaglandin E2 generation by colon cancer cells: role of cytosolic phospholipase A2-alpha and kinase signaling pathways

Cyclooxygenase (COX)-2-derived prostaglandin (PG)E(2) controls many aspects of colon cancer development, modulating from apoptosis resistance and cell proliferation to angiogenesis, invasion, and metastasis. Here, we investigated the role of different phospholipases (PL)A(2) in supplying arachidonic acid (AA) for COX-2-dependent PGE(2) generation and signaling pathways involved in activation of colon cancer cells by a physiologically relevant stimulus. To emulate the hypertonic environment found physiologically in colon, the human colon cancer cell line Caco-2 was maintained in hypertonic complete DMEM medium. Human colon cancer cell line Caco-2 exposed to a hypertonic environment responded with marked AA release, COX-2 induction and PGE(2) generation. Selective secretory (s)PLA(2) and calcium-independent (i)PLA(2) inhibitors did not modify PGE(2) generation, while either COX-2 or cytosolic (c)PLA(2) inhibitors completely inhibited PGE(2) generation. cPLA(2)-alpha was responsible for AA supply for PGE(2) generation, but had no role in COX-2 induction. Mitogen-activated protein (MAP) kinases, ERK 1/2, p38, and JNK, participated in the signaling events that lead to PGE(2) generation by modulating AA release, but only ERK 1/2 was involved in COX-2 upregulation. Our results indicate that hypertonic stress activates PGE(2) generation by Caco-2 cells through a mechanism dependent on MAP kinase-regulated AA mobilization, increased cPLA(2)-alpha activity, and COX-2 induction.

F-Prostaglandin receptor regulates endothelial cell function via fibroblast growth factor-2

Background

Prostaglandin (PG) F_2α is a key regulator of endometrial function and exerts its biological action after coupling with its heptahelical G protein-coupled receptor (FP receptor). In endometrial adenocarcinoma the FP receptor expression is elevated. We have shown previously that PGF_2α-FP receptor signalling in endometrial adenocarcinoma cells can upregulate several angiogenic factors including fibroblast growth factor-2 (FGF2). In the present study, we investigated the paracrine effect of conditioned medium produced via PGF_2α-FP receptor signalling in endometrial adenocarcinoma cells stably expressing the FP receptor (Ishikawa FPS cells), on endothelial cell function.

Results

Conditioned medium (CM) was collected from FPS cells after 24 hrs treatment with either vehicle (V CM) or 100 nM PGF_2α (P CM). Treatment of human umbilical vein endothelial cells (HUVECs) with P CM significantly enhanced endothelial cell differentiation (network formation) and proliferation. Using chemical inhibitors of intracellular signalling, we found that P CM-stimulated endothelial cell network formation was mediated by secretion of endothelial PGF_2α and activation of endothelial FP receptors, following FGF2-FGFR1 signalling, phosphorylation of ERK1/2 and induction of COX-2. Whereas, P CM stimulation of endothelial cell proliferation occurred independently of PGF_2α secretion via an FGF2-FGFR1-ERK1/2 dependent mechanism involving activation of the mTOR pathway.

Conclusions

Taken together, we have shown a novel mechanism whereby epithelial prostaglandin F_2α-FP signalling regulates endothelial cell network formation and proliferation. In addition we provide novel in vitro evidence to suggest that prostaglandin F_2α can directly regulate endothelial cell network formation but not endothelial cell proliferation. These findings have relevance for pathologies where the FP receptor is aberrantly expressed, such as endometrial adenocarcinoma, and provide in vitro evidence to suggest that targeting the FP receptor could provide an anti-angiogenic approach to reducing tumour vasculature and growth.

Biomarkers and the genetics of early neoplastic lesions

It has become increasingly evident that the study of DNA is inadequate to explain many, if not most, aspects of the development and progression of neoplastic lesions from pre-invasive lesions to metastasis. Thus, the term "genetic" can no longer refer to just the study of the genome. Much of the action in genetic research now shifts to the methods by which the pre-mRNA from one gene is processed to yield multiple different proteins, different quantities of the same protein as well as other forms of regulating RNA. Thus, the age of post-transcriptional processing and epigenetic control of the transfer of information from the genome has arrived. The mechanisms of post-transcriptional processing and epigenetic control that must be characterized in greater detail including alternate splicing, regulation of mRNA degradation, RNA regulatory factors including those factors which extensively edit mRNAs, control of translation, and control of protein stability and degradation. This chapter reviews many of the processes that control information from the genome to proteins and how these factors lead from less than 40,000 genes to more than an order of magnitude increase more proteins which actually control the phenotypes of cells - normal or neoplastic. It is usually the products of genes (e.g., mRNA, microRNA and proteins) that are the molecular markers that will control translational research and ultimately, individualized (personal) medical approaches to disease. This chapter emphasizes how the process of neoplasia "hijacks" the normal processes of cellular operations, especially those processes that are important in the normal development of the organisms - including proliferation, cellular death, angiogenesis, cellular mobility and invasion, and immunoregulation to ensure neoplastic development, survival and progression. This chapter reviews the wide range of processes controlling the information that flows from the genome to proteins and emphasizes how molecular steps in pure processes can be used as biomarkers to study prevention, treatment and/or management of diseases.

Interleukin-11 in endometrial adenocarcinoma is regulated by prostaglandin F2alpha-F-prostanoid receptor interaction via the calcium-calcineurin-nuclear factor of activated T cells pathway and negatively regulated by the regulator of calcineurin-1

Interleukin-11 (IL-11) up-regulates the proliferative and invasive capacity of many cancers. Coexpression of glycoprotein 130 (GP130) and IL-11 receptor alpha (IL-11Ralpha) is necessary for high-affinity binding of IL-11 to IL-11Ralpha. This study investigated the expression of IL-11 and role of prostaglandin F(2alpha)-F-prostanoid receptor (FP receptor) signaling in the modulation of IL-11 expression in endometrial adenocarcinoma cells. Localization of IL-11, IL-11Ralpha, and GP130 expression was performed by immunohistochemistry. IL-11 and regulator of calcineurin 1 isoform 4 (RCAN1-4) mRNA and protein expression were determined by real-time RT-PCR and/or enzyme-linked immunosorbent assay/Western blot analysis using Ishikawa endometrial adenocarcinoma cells stably expressing the FP receptor (FPS cells) and endometrial adenocarcinoma explants. IL-11 mRNA expression was significantly elevated in endometrial adenocarcinoma samples compared with normal endometrium and increased with tumor grade. IL-11 protein expression localized with FP receptor, IL-11Ralpha, and GP130 in the neoplastic glandular epithelium of endometrial adenocarcinomas. Prostaglandin F(2alpha)-FP receptor signaling significantly elevated the expression of IL-11 mRNA and protein in a Gq-protein kinase C-calcium-calcineurin-nuclear factor of activated T cells-dependent manner in FPS cells. The calcineurin signaling pathway is known to be controlled by the RCAN (RCAN1-4). Indeed, RCAN1-4 expression was significantly elevated in well-differentiated endometrial adenocarcinoma compared with normal endometrium and was found to decrease with tumor grade and negatively regulate IL-11 expression in vitro. This study has highlighted a new mechanism regulating IL-11 expression in endometrial adenocarcinoma cells by the FP receptor via the calcium-calcineurin-nuclear factor of activated T cells pathway.

Invasion associated up-regulation of nuclear factor kappaB target genes in colorectal cancer

BACKGROUND

: Colorectal cancer (CRC) displays intratumoral heterogeneity with less differentiated tumor cells at the invasive front (IF) than in the tumor center (TC). The authors previously observed that several genes were overexpressed at the IF of CRC with relations to inflammatory processes. Because nuclear factor kappaB (NF-kappaB), a dimeric transcription factor, is a major regulator of such processes, and because its target genes are involved in immune response, cell growth control, and cell survival, the expression of NF-kappaB target genes was investigated comparatively in CRC.

METHODS

: By using gene array profiling, NF-kappaB target gene expression was assessed in CRCs that expressed human mutL homolog 1 (hMLH1), hMSH2, and nuclear beta-catenin by comparing expression at the IF, in the TC, and in normal mucosa. In addition, 5 NF-kappaB target genes with high differential expression were validated by using immunohistochemistry.

RESULTS

: The expression of NF-kappaB target genes in the TC, at the IF, and in normal mucosa was distinct; whereas, specifically at the IF, most differentially expressed NF-kappaB targets were up-regulated. Moreover, the results indicated that the expression diverged between epithelial tumor cells and inflammatory stromal cells.

CONCLUSIONS

: Because the results demonstrated that inflammation and the activation of NF-kappaB signaling promoted CRC invasiveness, the current study provided further evidence that downstream targets of NF-kappaB signaling may be specifically relevant in invasion and progression of CRC. Finally, as has been suggested for colitis-associated cancer, the authors of this report concluded that the inhibition of NF-kappaB signaling also may be an additional option for the treatment of sporadic CRC. Cancer 2009. (c) 2009 American Cancer Society.

The role of COX-2 in intestinal inflammation and colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease, including at least three major forms: hereditary, sporadic and colitis-associated CRC. A large body of evidence indicates that genetic mutations, epigenetic changes, chronic inflammation, diet and lifestyle are the risk factors for CRC. As elevated cyclooxygenase-2 (COX-2) expression was found in most CRC tissue and is associated with worse survival among CRC patients, investigators have sought to evaluate the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors (COXIBs) on CRC. The epidemiological studies, clinical trials and animal experiments indicate that NSAIDs are among the most promising chemopreventive agents for this disease. NSAIDs exert their anti-inflammatory and antitumor effects primarily by reducing prostaglandin production by inhibition of COX-2 activity. In this review, we highlight breakthroughs in our understanding of the roles of COX-2 in CRC and inflammatory bowel disease. These recent data provide a rationale for re-evaluating COX-2 as both the prognostic and the predictive marker in a wide variety of malignancies and for renewing the interest in evaluating relative benefits and risk of COXIBs in appropriately selected patients for cancer prevention and treatment.

Blood flow patterns spatially associated with platelet aggregates in murine colitis

In the normal murine mucosal plexus, blood flow is generally smooth and continuous. In inflammatory conditions, such as chemically-induced murine colitis, the mucosal plexus demonstrates markedly abnormal flow patterns. The inflamed mucosal plexus is associated with widely variable blood flow velocity as well as discontinuous and even bidirectional flow. To investigate the mechanisms responsible for these blood flow patterns, we used intravital microscopic examination of blood flow within the murine mucosal plexus during dextran sodium sulphate-and trinitrobenzenesulfonic acid-induced colitis. The blood flow patterns within the mucosal plexus demonstrated flow exclusion in 18% of the vessel segments (P < 0.01). Associated with these segmental exclusions was significant variation in neighboring flow velocities. Intravascular injection of fluorescent platelets demonstrated platelet incorporation into both fixed and rolling platelet aggregates. Rolling platelet aggregates (mean velocity 113 microm/sec; range, 14-186 microm/sec) were associated with reversible occlusions and flow variations within the mucosal plexus. Gene expression profiles of microdissected mucosal plexus demonstrated enhanced expression of genes for CCL3, CXCL1, CCL2, CXCL5, CCL7, CCL8, and Il-1b (P < 0.01), and decreased expression of CCL6 (P < 0.01). These results suggest that platelet aggregation, activated by the inflammatory mileau, contributes to the complex flow dynamics observed in acute murine colitis.

Prostaglandin F(2alpha)-F-prostanoid receptor regulates CXCL8 expression in endometrial adenocarcinoma cells via the calcium-calcineurin-NFAT pathway

Pro-inflammatory mediators, like prostaglandin (PG) and chemokines, promote tumourigenesis by enhancing cell proliferation, migration of immune cells and recruitment of blood vessels. Recently we showed elevated expression of the chemokine (C-X-C motif) receptor 2 (CXCR2) in endometrial adenocarcinomas localized to neutrophils and neoplastic epithelial and vascular cells. Furthermore we found that PGF_2α-F-prostanoid (FP) receptor regulates the expression of the CXCR2 ligand CXCL1, to promote neutrophil chemotaxis in endometrial adenocarcinomas. In the present study we identified another CXCR2 ligand, CXCL8 as a target for PGF_2α-FP receptor signalling which enhances epithelial cell proliferation in endometrial adenocarcinoma cells in vitro and in nude mice in vivo. We found that PGF_2α-FP receptor interaction induces CXCL8 expression in endometrial adenocarcinoma cells via the protein kinase C–calcium–calcineurin–NFAT signaling pathway. Promoter analysis revealed that CXCL8 transcriptional activation by PGF_2α signaling is mediated by cooperative interactions between the AP1 and NFAT binding sites. Furthermore, PGF_2α via the FP receptor induced the expression of the regulator of calcineurin 1 isoform 4 (RCAN1-4) via the calcineurin/NFAT pathway in a reciprocal manner to CXCL8. Using an adenovirus to overexpress RCAN1-4, we found that RCAN1-4 is a negative regulator of CXCL8 expression in endometrial adenocarcinoma cells. Taken together our data have elucidated the molecular and cellular mechanism whereby PGF_2α regulates CXCL8 expression via the FP receptor in endometrial adenocarcinomas and have highlighted RCAN1-4 as a negative regulator of CXCL8 expression which may be exploited therapeutically to inhibit CXCL8-mediated tumour development.

The role of chemokines in intestinal inflammation and cancer

Chronic inflammation is a risk factor for several gastrointestinal malignancies, including colorectal cancer. Recent epidemiological studies and clinical trials demonstrate that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) markedly reduced the relative risk of colorectal cancer. Chronic inflammation associated with development of cancer is partly driven by the chemokine system. Chemokines are chemoattractant cytokines that recruit leukocytes from the circulatory system to local inflammatory sites. In this review, we highlight recent breakthroughs in our understanding of the role of chemokines in inflammatory bowel disease and colorectal cancer from animal models and human studies. These findings provide a rationale for the development of new anti-inflammatory therapeutic approaches for prevention and/or treatment of inflammatory bowel disease and colorectal cancer.

COX-2, VEGF and tumour angiogenesis

Epidemiological evidence suggests a protective effective of regular NSAID use against developing cancer. Cyclooxygenase-2, a target of NSAIDs, is upregulated in many cancers and has been associated with increased VEGF production and angiogenesis. Angiogenesis is the formation of new vessels from existing vasculature and as an essential process for tumour development represents an important therapeutic target. Following an extensive review of the literature this article details the current knowledge on the role of COX-2 in tumorigenesis focusing on its relationship to angiogenesis and VEGF production by tumour cells. While COX-2 is clearly detrimental to prognosis and NSAIDs have a beneficial effect, the possibility of COX-2 independent effects being partly or wholly responsible for this benefit cannot be excluded.

Identification of proteins involved in neural progenitor cell targeting of gliomas

BACKGROUND

Glioblastoma are highly aggressive tumors with an average survival time of 12 months with currently available treatment. We have previously shown that specific embryonic neural progenitor cells (NPC) have the potential to target glioma growth in the CNS of rats. The neural progenitor cell treatment can cure approximately 40% of the animals with malignant gliomas with no trace of a tumor burden 6 months after finishing the experiment. Furthermore, the NPCs have been shown to respond to signals from the tumor environment resulting in specific migration towards the tumor. Based on these results we wanted to investigate what factors could influence the growth and progression of gliomas in our rodent model.

METHODS

Using microarrays we screened for candidate genes involved in the functional mechanism of tumor inhibition by comparing glioma cell lines to neural progenitor cells with or without anti-tumor activity. The expression of candidate genes was confirmed at RNA level by quantitative RT-PCR and at the protein level by Western blots and immunocytochemistry. Moreover, we have developed in vitro assays to mimic the antitumor effect seen in vivo.

RESULTS

We identified several targets involved in glioma growth and migration, specifically CXCL1, CD81, TPT1, Gas6 and AXL proteins. We further showed that follistatin secretion from the NPC has the potential to decrease tumor proliferation. In vitro co-cultures of NPC and tumor cells resulted in the inhibition of tumor growth. The addition of antibodies against proteins selected by gene and protein expression analysis either increased or decreased the proliferation rate of the glioma cell lines in vitro.

CONCLUSION

These results suggest that these identified factors might be useful starting points for performing future experiments directed towards a potential therapy against malignant gliomas.

Prostaglandin F2alpha-F-prostanoid receptor signaling promotes neutrophil chemotaxis via chemokine (C-X-C motif) ligand 1 in endometrial adenocarcinoma

The prostaglandin F(2alpha) (PGF(2alpha)) receptor (FP) is elevated in endometrial adenocarcinoma. This study found that PGF(2alpha) signaling via FP regulates expression of chemokine (C-X-C motif) ligand 1 (CXCL1) in endometrial adenocarcinoma cells. Expression of CXCL1 and its receptor, CXCR2, are elevated in cancer tissue compared with normal endometrium and localized to glandular epithelium, endothelium, and stroma. Treatment of Ishikawa cells stably transfected with the FP receptor (FPS cells) with 100 nmol/L PGF(2alpha) increased CXCL1 promoter activity, mRNA, and protein expression, and these effects were abolished by cotreatment of cells with FP antagonist or chemical inhibitors of Gq, epidermal growth factor receptor, and extracellular signal-regulated kinase. Similarly, CXCL1 was elevated in response to 100 nmol/L PGF(2alpha) in endometrial adenocarcinoma explant tissue. CXCL1 is a potent neutrophil chemoattractant. The expression of CXCR2 colocalized to neutrophils in endometrial adenocarcinoma and increased neutrophils were present in endometrial adenocarcinoma compared with normal endometrium. Conditioned media from PGF(2alpha)-treated FPS cells stimulated neutrophil chemotaxis, which could be abolished by CXCL1 protein immunoneutralization of the conditioned media or antagonism of CXCR2. Finally, xenograft tumors in nude mice arising from inoculation with FPS cells showed increased neutrophil infiltration compared with tumors arising from wild-type cells or following treatment of mice bearing FPS tumors with CXCL1-neutralizing antibody. In conclusion, our results show a novel PGF(2alpha)-FP pathway that may regulate the inflammatory microenvironment in endometrial adenocarcinoma via neutrophil chemotaxis.

Chemokines and angiogenesis in rheumatoid arthritis

In rheumatoid arthritis, chemokines mediate the migration of inflammatory leukocytes into the synovium. Among the four known chemokine families, CXC, CC chemokines and fractalkine seem to be of outstanding importance in this process. Angiogenesis, the formation of new vessels, is also important during the perpetuation of inflammation underlying rheumatoid arthritis. In this review, authors discuss the role of the most important chemokines and chemokine receptors in arthritis-associated neovascularization. The process and regulation of angiogenesis are described in this context as well. Apart from discussing the pathogenic role of chemokines and chemokine receptors in arthritic vessel formation, authors also review the important relevance of chemokines and angiogenesis for therapeutic intervention.

Lipidomic analysis of dynamic eicosanoid responses during the induction and resolution of Lyme arthritis

Eicosanoids and other bioactive lipid mediators are indispensable regulators of biological processes, as demonstrated by the numerous inflammatory diseases resulting from their dysregulation, including cancer, hyperalgesia, atherosclerosis, and arthritis. Despite their importance, a robust strategy comparable with gene or protein array technology for comprehensively analyzing the eicosanoid metabolome has not been forthcoming. We have developed liquid chromatography-tandem mass spectrometry methodology that quantitatively and comprehensively analyzes the eicosanoid metabolome and utilized this approach to characterize eicosanoid production during experimental Lyme arthritis in mice infected with the bacterium Borrelia burgdorferi. Eicosanoids were extracted throughout infection from the joints of Lyme arthritis-resistant and -susceptible mice and subjected to lipidomic profiling. We identified temporal and quantitative differences between these mouse strains in the production of eicosanoids, which correlated with differences in arthritis development. The eicosanoid biosynthetic enzyme cyclooxygenase (COX)-2 has been implicated in the regulation of Lyme arthritis pathology, and subsequent lipidomic profiling of B. burgdorferi-infected COX-2(-/-) mice identified reductions not only in COX-2 products but, surprisingly, also significant off-target reductions in 5-lipoxygenase metabolites. Our results demonstrate the utility of a comprehensive lipidomic approach for identifying potential contributors to disease pathology and may facilitate the development of more precisely targeted treatment strategies.

Role of the low-affinity leukotriene B4 receptor BLT2 in VEGF-induced angiogenesis

OBJECTIVE

The leukotriene B(4) (LTB(4)) receptor BLT2 is expressed in endothelium, but no clear physiological function for it has yet been identified, especially in vascular angiogenesis. The purpose of this study is to characterize the potential function of BLT2 in vascular endothelial growth factor (VEGF)-induced angiogenesis.

METHODS AND RESULTS

VEGF significantly upregulates BLT2 expression in human umbilical vein endothelial cells (HUVECs), and BLT2 knockdown by siRNA or inhibition of BLT2 by a specific BLT2 antagonist LY255283 attenuates VEGF-induced angiogenesis, which was determined by its effect on the formation of tube-like structures and on transmigration. The role of BLT2 in VEGF-induced angiogenesis was more evident in vivo, where BLT2 inhibition by LY255283 almost completely blocked VEGF-induced vessel formation in Matrigel-plug assays. In addition, we found that VEGF upregulates synthesis of the BLT2 ligand, 12(S)-hydroxyeicosatetraenoic acid (HETE). siRNA knockdown of 12-lipoxygenase (12-LO) expression attenuates VEGF-induced angiogenesis in HUVECs, and the addition of 12(S)-HETE to the 12-LO knockdown-HUVECs restores VEGF-induced angiogenesis. The activation of BLT2 itself by either 12(S)-HETE or LTB(4) evoked significant angiogenic phenotypes, both in vitro and in vivo.

CONCLUSIONS

Our findings indicate that BLT2 plays an essential role in mediating VEGF-induced angiogenesis.

Identification of GRO1 as a critical determinant for mutant p53 gain of function

Mutant p53 gain of function contributes to cancer progression, increased invasion and metastasis potentials, and resistance to anticancer therapy. The ability of mutant p53 to acquire its gain of function is shown to correlate with increased expression of progrowth genes, such as c-MYC, MDR1, and NF-kappaB2. However, most of the published studies to identify mutant p53 target genes were performed in a cell system that artificially overexpresses mutant p53. Thus, it remains unclear whether such mutant p53 targets can be regulated by endogenous physiological levels of mutant p53. Here, we utilized SW480 and MIA-PaCa-2 cells, in which endogenous mutant p53 can be inducibly knocked down, to identify mutant p53 target genes that potentially mediate mutant p53 gain of function. We found that knockdown of mutant p53 inhibits GRO1 expression, whereas ectopic expression of mutant R175H in p53-null HCT116 cells increases GRO1 expression. In addition, we found that endogenous mutant p53 is capable of binding to and activating the GRO1 promoter. Interestingly, ectopic expression of GRO1 can rescue the proliferative defect in SW480 and MIA-PaCa-2 cells induced by knockdown of mutant p53. Conversely, knockdown of endogenous GRO1 inhibits cell proliferation and thus abrogates mutant p53 gain of function in SW480 cells. Taken together, our findings define a novel mechanism by which mutant p53 acquires its gain of function via transactivating the GRO1 gene in cancer cells. Thus, targeting GRO1 for cancer therapy would be applicable to a large portion of human tumors with mutant p53, but the exploration of GRO1 as a potential target should take the mutation status of p53 into consideration.

Amphotericin B up-regulates angiogenic genes in hepatocellular carcinoma cell lines

BACKGROUND

Amphotericin B (AmB) has a discordant influence on epirubicin (4'-epidoxorubicin) cytotoxicity in hepatocellular carcinoma (HCC). This indicates that the cellular function of HCC may be significantly influenced by AmB. Whether the influence of AmB on HCC has any possibility to influence cancer growth has not been studied. This study was to try and clarify this issue.

MATERIALS AND METHODS

Two HCC cell lines including one without augmentation of the epirubicin cytotoxicity by AmB (cell line A; HCC24/KMUH) and one with this effect (cell line B; HCC38/KMUH) were studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and whole human genome microarray (experimental group: 2.5 microg mL(-1) AmB).

RESULTS

Differential expressions of genes induced by AmB in two cell lines had no influence on cell proliferation as determined by MTT assay. Only cell line B showed up-regulation of genes related to oxidative stress, acute phase reaction, cytokine-cytokine receptor interaction and complement and coagulation cascades. Among the chemokine genes up-regulated by AmB, five genes (CCL2, CXCL1, CXCL5, CXCL6, IL8) were angiogenic. Cell line B also showed up-regulation of one angiogenic C10orf10 gene and down-regulation of one angiostatic chemokine gene (CXCL10). Up- or down-regulation of other genes in cell line A and B did not show any evidence to promote angiogenesis.

CONCLUSION

AmB has the capacity to concomitantly up-regulate angiogenic genes in HCC cells susceptible to AmB-induced oxidative stress.

Diurnal variation of the human adipose transcriptome and the link to metabolic disease

Background

Circadian (diurnal) rhythm is an integral part of the physiology of the body; specifically, sleep, feeding behavior and metabolism are tightly linked to the light-dark cycle dictated by earth's rotation.

Methods

The present study examines the effect of diurnal rhythm on gene expression in the subcutaneous adipose tissue of overweight to mildly obese, healthy individuals. In this well-controlled clinical study, adipose biopsies were taken in the morning, afternoon and evening from individuals in three study arms: treatment with the weight loss drug sibutramine/fasted, placebo/fed and placebo/fasted.

Results

The results indicated that diurnal rhythm was the most significant driver of gene expression variation in the human adipose tissue, with at least 25% of the genes having had significant changes in their expression levels during the course of the day. The mRNA expression levels of core clock genes at a specific time of day were consistent across multiple subjects on different days in all three arms, indicating robust diurnal regulation irrespective of potential confounding factors. The genes essential for energy metabolism and tissue physiology were part of the diurnal signature. We hypothesize that the diurnal transition of the expression of energy metabolism genes reflects the shift in the adipose tissue from an energy-expending state in the morning to an energy-storing state in the evening. Consistent with this hypothesis, the diurnal transition was delayed by fasting and treatment with sibutramine. Finally, an in silico comparison of the diurnal signature with data from the publicly-available Connectivity Map demonstrated a significant association with transcripts that were repressed by mTOR inhibitors, suggesting a possible link between mTOR signaling, diurnal gene expression and metabolic regulation.

Conclusion

Diurnal rhythm plays an important role in the physiology and regulation of energy metabolism in the adipose tissue and should be considered in the selection of novel targets for the treatment of obesity and other metabolic disorders.

G protein-coupled receptor connectivity to NF-kappaB in inflammation and cancer

Complex intracellular network interactions regulate gene expression and cellular behavior. Whether at the site of inflammation or within a tumor, individual cells are exposed to a plethora of signals. The transcription factor nuclear factor-kappaB (NF-kappaB) regulates genes that control key cellular activities involved in inflammatory diseases and cancer. NF-kappaB is regulated by several distinct signaling pathways that may be activated individually or simultaneously. Multiple ligands and heterologous cell-cell interactions have an impact on NF-kappaB activity. The G protein-coupled receptor (GPCR) superfamily makes up the largest class of transmembrane receptors in the human genome and has multiple molecularly distinct natural ligands. GPCRs regulate proliferation, differentiation, and chemotaxis and play a major role in inflammatory diseases and cancer. Both GPCRs and NF-kappaB have been, and continue to be, major targets for drug discovery. A clear understanding of network interactions between GPCR signaling pathways and those that control NF-kB may be valuable for the development of better drugs and drug combinations.

The COX-2/PGE2 pathway: key roles in the hallmarks of cancer and adaptation to the tumour microenvironment

It is widely accepted that alterations to cyclooxygenase-2 (COX-2) expression and the abundance of its enzymatic product prostaglandin E(2) (PGE(2)) have key roles in influencing the development of colorectal cancer. Deregulation of the COX-2/PGE(2) pathway appears to affect colorectal tumorigenesis via a number of distinct mechanisms: promoting tumour maintenance and progression, encouraging metastatic spread, and perhaps even participating in tumour initiation. Here, we review the role of COX-2/PGE(2) signalling in colorectal tumorigenesis and highlight its ability to influence the hallmarks of cancer--attributes defined by Hanahan and Weinberg as being requisite for tumorigenesis. In addition, we consider components of the COX-prostaglandin pathway emerging as important regulators of tumorigenesis; namely, the prostanoid (EP) receptors, 15-hydroxyprostaglandin dehydrogenase and the prostaglandin transporter. Finally, based on recent findings, we propose a model for the cellular adaptation to the hypoxic tumour microenvironment that encompasses the interplay between COX-2, hypoxia-inducible factor 1 and dynamic switches in beta-catenin function that fine-tune signalling networks to meet the ever-changing demands of a tumour.

Suppression of invasive properties of colorectal carcinoma SW480 cells by 15-hydroxyprostaglandin dehydrogenase gene

Colorectal carcinoma (CRC) is often lethal when invasion and/or metastasis occur. NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme involved in prostaglandin (including PGE(2)) bio-inactivation, is down-expressed in several epithelial malignancies including CRC. Although its role in the suppression of colon tumorigenesis has been well learned, little is known about the role of 15-PGDH in the process of tumor metastasis. Here, we tested the hypothesis that 15-PGDH over-expression in CRC cells results in decreased cell motility and invasion. In this study, 15-PGDH was re-expressed in SW480 cells by the use of gene transient transfection with eukaryotic expression vector pcDNA3.1-PGDH. We confirmed the over-expression of 15-PGDH protein by Western blot and enzymatic activity assay. The cell motility was tested by counting the number of cells crossing an 8-micron pore size PET membrane and by measuring cells migration distance through wound healing assay. Furthermore, cell invasive activity was evaluated by counting the number of cells invading through a Matrigel-coated membrane simulating basement membrane. The effects of 15-PGDH on the adhesion were investigated by MTT assay. Ectopic expression of 15-PGDH in SW480 cancer cells significantly inhibited the cell migratory and invasive capacity in vitro by approximately 1.9- and 8.4-fold, respectively. To test the hypothesis that 15-PGDH affects proteases and inactivates extracellular matrix (ECM), Western blot and gelatin zymography were performed by using serum-free conditioned medium. The results showed that re-expression of 15-PGDH suppresed matrix metalloproteinase-2 (MMP2) synthesis and secretion. In addition, the analysis of the MMP2 activity indicated that re-expression of 15-PGDH could inhibit activation of MMP2. Furthermore, we found that 15-PGDH inhibited cell adhesion to ECM and reduced CD44 expression in SW480 cell. Taken together, these results suggest that induced 15-PGDH expression may contribute to the inhibition of the invasive and metastatic capacity of colon cancer cells in vitro.

Innate immune signalling at intestinal mucosal surfaces: a fine line between host protection and destruction

PURPOSE OF REVIEW

Emerging evidence underscores that inappropriate innate immune responses driven by commensals contribute to the pathogenesis of chronic inflammatory bowel diseases in genetically susceptible hosts. The present review focuses on defining the recently described mechanistic functions through which the innate immune signalling apparatus shapes mucosal homeostasis of the intestine in health and disease.

RECENT FINDINGS

Commensal-induced innate immune signalling actively drives at least six major interdependent functions to control homeostasis in the healthy intestinal mucosa: 1) barrier preservation, 2) inhibition of apoptosis and inflammation, 3) acceleration of wound repair and tissue regeneration, 4) exclusion of harmful pathogens through autophagy and other antimicrobial defenses, while 5) maintaining immune tolerance towards harmless commensals, and 6) linkage to adaptive immunity. Any disturbance of this peaceful and mutually beneficial host-commensal relationship may imbalance innate immune signalling, which predisposes to chronic intestinal inflammation and associated tumourigenesis in inflammatory bowel diseases.

SUMMARY

Recent advances have highlighted the complex mechanistics and functional diversity of innate immunity that paradoxically mediate both protective and destructive responses in the intestinal mucosa. Related signalling targets may offer novel therapeutic approaches in the treatment of inflammatory bowel diseases and inflammation-related cancer.

Moving targets: cell migration inhibitors as new anti-inflammatory therapies

The pharmaceutical industry has targeted various types of molecules to subdue inflammatory diseases. Drugs that disrupt cell migration appear particularly promising in clinical trials and in many animal models of inflammatory disease. Cell migration inhibitors not only interfere with migration of cells to a tissue, but also can affect other necessary processes such as mediator release and angiogenesis. However, the question is whether drugs that target adhesion molecules or chemoattractant receptors will prove superior to drugs that target other molecular types. This review proclaims the virtues of targeting cell migration-related molecules for development of new anti-inflammatory and anti-tumor based drugs. It is likely that cell migration inhibitors will transform the way in which many human inflammatory diseases and cancers are treated.

Loss of cannabinoid receptor 1 accelerates intestinal tumor growth

Although endocannabinoid signaling is important for certain aspects of gastrointestinal homeostasis, the role of the cannabinoid receptors (CB) in colorectal cancer has not been defined. Here we show that CB1 expression was silenced in human colorectal cancer due to methylation of the CB1 promoter. Our genetic and pharmacologic studies reveal that loss or inhibition of CB1 accelerated intestinal adenoma growth in Apc(Min/+) mice whereas activation of CB1 attenuated intestinal tumor growth by inducing cell death via down-regulation of the antiapoptotic factor survivin. This down-regulation of survivin by CB1 is mediated by a cyclic AMP-dependent protein kinase A signaling pathway. These results indicate that the endogenous cannabinoid system may represent a potential therapeutic target for prevention or treatment of colorectal cancer.