Macrophages are cells of the innate immune system that can be found in large quantities in cancer tumors and affect cancer progression by regulating growth and invasiveness of cancer cells. There are two main phenotypes of macrophages denoted M1 and M2. In this thesis, the M1 and M2 phenotype of human macrophages were characterized, and effects of the macrophages on the growth and invasiveness of colon and lung cancer cells were studied. Macrophages of the M1 phenotype, but not the M2 phenotype, inhibited growth of both colon and lung cancer cells, and the inhibition for some of the cancer cell lines was induced by cell cycle arrest in the G1/G0 and/or G2/M cell cycle phases. In the colon cancer cell line, the macrophage induced cell cycle arrest was found to attenuate the cytotoxic effect of the chemotherapeutic drug 5-FU. Macrophages were also shown to express high levels of proteases (matrix metalloproteinase-2 and 9) and high levels of proteins of the urokinase-type plasminogen activator (uPA) system, in comparison to the lung cancer cell lines studied. Expression of these has been found to predict poor outcome in lung cancer, and the results suggest macrophages to be important contributors of these in lung tumors. Furthermore, the M1 phenotype was found to express higher levels of the uPA receptor than the M2 phenotype. Prostaglandin E2 (PGE2) is a potent inflammatory molecule expressed by e.g. macrophages and monocytes, and inhibition of its expression has been shown to reduce the risk of colon cancer. Green tea and black tea was found to be potent inhibitors of PGE2 formation in human monocytes, and the inhibitory effects of green tea was likely due to its content of the polyphenol epigallocatechin gallate. Rooibos tea also inhibited PGE2 formation, but was less potent than green and black tea. The primary mechanism for the inhibition was via inhibition of expression of enzymes in the PGE2 formation pathway, and primarily microsomal prostaglandin synthase-1. / Macrophages are cells of the immune system often found in large numbers in cancer tumors. They affect multiple aspects of cancer progression, including growth and spread of cancer cells, and the efficacy of treatments. There are two major macrophage phenotypes denoted M1 and M2, that have mainly pro- and anti-inflammatory properties, respectively. In this thesis, M1 and M2 macrophages were characterized and effects of them on different aspects of cancer progression were studied using culture of colon, and lung cancer cells. The M1 phenotype inhibited proliferation of cancer cells from both colon and lung. The growth inhibition was for some cell lines accompanied by cell cycle arrest. The macrophage induced cell cycle arrest was found to protect colon cancer cells from the cytostatic drug 5-fluorouracil. Prostaglandin E2 (PGE2) contributes to colon cancer development and treatment of monocytes with tea extracts inhibited PGE2 formation via inhibition of expression of microsomal prostaglandin E synthase-1. Proteases can degrade the extracellular matrix of a tumor to facilitate cancer cell invasion and metastasis. The M1 and M2 phenotypes of macrophages expressed several protease activity related genes to a greater extent than lung cancer cells, and M1 more so than the M2 phenotype.

Obesity is an established risk and progression factor for many types of cancer, including pancreatic and colon cancer, and is characterized by abnormal metabolic hormone production and a chronic low-grade state of inflammation. However, the links between obesity, hormones, inflammation and tumorigenesis in colon and pancreatic tissue are poorly understood. Calorie restriction (CR), an anti-obesity dietary regimen with potent anticancer effects, reduces serum metabolic hormones and protumorigenic cytokines. Insulin-like growth factor (IGF)-1 is a metabolic hormone that activates NF-[kappa]B, a key regulator of inflammation. NF-[kappa]B is a transcription factor that mediates transcription of many cancer- and inflammation-related genes and is upregulated in both colon and pancreatic cancer. We hypothesized that CR inhibits colon and pancreatic tumor cell growth through modulation of hormone-stimulated NF-[kappa]B activation and protumorigenic gene expression. To test this hypothesis, we used CR and ad libitum feeding to generate a lean and overweight (control) phenotype, respectively; in C57BL/6 mice transplanted with MC38 colon cancer cells or Panc 02 pancreatic cancer cells, and analyzed the effect of diet on circulating hormone levels, markers of inflammation, and tumor growth. We also investigated the in vitro effects of IGF-1 on NF-[kappa]B activation and downstream protumorigenic gene expression in MC38 and Panc 02 cells. CR, relative to control diet, reduced body weight, circulating IGF-1 levels, and transplanted MC38 and Panc 02 tumor growth, as well as protumorigenic gene expression in the MC38 and Panc 02 tumor microenvironment. IGF-1 increased cell viability, NF-[kappa]B nuclear translocation and DNA binding, transcriptional activation, and downstream gene expression of inflammation and other protumorigenic genes in MC38 colon cancer cells and Panc 02 pancreatic cancer cells in vitro. Knockdown studies of NF-[kappa]B in Panc 02 cells using si-RNA established that the IGF-1-induced increase in protumorigenic gene expression is mediated, at least partially, through an NF-[kappa]B-dependent mechanism. In conclusion, these findings in models of pancreatic and colon cancer help clarify the links between obesity, IGF-1, NF-[kappa]B-mediated inflammation, and cancer. This work provides the underpinnings for several new molecular targets and strategies to test in model systems and translational studies for preventing or controlling obesity-related cancer. / text

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Accumulated genetic and epigenetic abnormalities contribute to the development of colon cancer. We have shown that a combination of fish oil (containing decosahexaenoic acid, DHA, 22:6 n-3) and pectin (fermented to butyrate by colonic microflora) is protective against colon carcinogenesis in part by regulating the expression of genes involved in apoptosis, leading to apoptosis induction. To determine how FO/P enhances apoptosis, we measured the expression of genes involved in apoptosis. We performed a pathway analysis on differentially expressed genes identified at three times during colon tumorigenesis: initiation, aberrant crypt foci (ACF) formation, and tumor stage, and compared these results with phenotypic observations at those times. At initiation, FO/P down-regulated the expression of genes involved with cell adhesion and enhanced apoptosis compared with corn oil/cellulose (CO/C). At the ACF stage, expression of genes involved in cell cycle regulation was modulated by FO/P and proliferation was reduced in FO/P rats compared with CO/C rats. FO/P increased apoptosis and the expression of genes that promote apoptosis at the tumor endpoint compared with CO/C. We next determined if changes in expression of genes involved in apoptosis by FO/P are associated with changes in promoter methylation of a key apoptosis regulator, Bcl-2. Genomic DNA was isolated from carcinogen-induced colon tumors and non-involved tissues. FO/P increased Bcl-2 promoter methylation in tumor tissues and colonocyte apoptosis relative to those observed with CO/C. A negative correlation between Bcl-2 DNA methylation and Bcl-2 mRNA levels was observed in the tumors. Additionally, we examined gene specific promoter methylation of 24 apoptosis-related genes using human colon cancer cells. Cells were treated with DHA or linoleic acid (18:2 n-6), and select cultures were also treated with butyrate. The combination of DHA and butyrate led to a significant reduction in the methylation of pro-apoptotic genes and an increase in apoptosis. These data suggest that part of the mechanisms involved in the induction of apoptosis by FO/P may be through epigenetic regulation of genes involved in apoptosis throughout colon carcinogenesis.

Non-steroidal anti-inflammatory drugs (NSAIDs) and their NO derivatives (NO-NSAIDs), and synthetic analogs are highly effective as anticancer agents that exhibit relatively low toxicity compared to most clinically used drugs. However, the mechanisms of action for NSAIDs and NO-NSAIDs are not well defined and this has restricted their clinical applications and applications for combined therapies. Earlier studies from our laboratory reported that specificity protein (Sp) transcription factors (Sp1, Sp3 and Sp4) are overexpressed in several types of human cancers including colon cancer and many Sp-regulated genes are pro-oncogenic and individual targets for cancer chemotherapy. Based on published results showing that NSAIDs downregulate several putative Sp-regulated genes, we hypothesized that the anticancer properties of NSAIDs may be due, in part, to downregulation of Sp transcription factors. NSAIDs including aspirin and tolfenamic acid (TA) and nitro derivatives of NSAIDs such as GT-094 have been investigated in colon cancer cells and in vivo xenograft models. Aspirin and TA induced apoptosis and decreased colon cancer cell growth and tumor growth in vivo and downregulated genes associated with cell growth, survival, and angiogenesis. Previous RNA interference studies in this laboratory have shown that many of these genes are regulated, in part, by Sp transcription factors Sp1, Sp3 and Sp4 that are overexpressed in colon and other cancer cell lines. Not surprisingly, these NSAIDs also decreased Sp1, Sp3 and Sp4 proteins and Sp-regulated gene products in colon cancer cells and this was due to caspase-dependent proteolysis of Sp1, Sp3 and Sp4 proteins. Aspirin-induced activation of caspases and degradation of Sp1, Sp3 and Sp4 was due to sequestration of zinc and could be reversed by addition of zinc sulphate, whereas TA mediated induction of caspases was independent of zinc ions and is currently being investigated. GT-094 is a novel NO chimera-containing NSAID, which also inhibited colon cancer cell proliferation and induced apoptosis; these effects were accompanied by decreased mitochondrial membrane potential (MMP) and induction of reactive oxygen species (ROS), and were reversed after cotreatment with the antioxidant glutathione. GT-094 also downregulated Sp and Sp-dependent gene products and was due to decreased expression of microRNA-27a (miR-27a) and induction of ZBTB10, an Sp transcriptional repressor that is regulated by miR-27a in colon cancer cells. Moreover, the effects of GT-094 on Sp1, Sp3, Sp4, miR-27a and ZBTB10 were also inhibited by glutathione suggesting that the anticancer activity of GT-094 in colon cancer cells is due, in part, to ROS-dependent disruption of miR-27a:ZBTB10. The importance of ROS induction in targeting Sp transcription factors was also confirmed using pro-oxidants such as ascorbic acid, hydrogen peroxide and t-butyl hydroperoxide and similar results have been observed in collaborative studies with other ROS inducers in colon cancer cells. Many cancer cell lines and tumors exhibit addiction to non-oncogenes such as Sp1, Sp3 and Sp4 for maintaining the oncogenic phenotype and future research will focus on the mechanisms of ROS-mediated targeting of Sp transcription factors which represents a novel approach for cancer chemotherapy.

Colon cancer is the third most common type of cancer, with high mortality throughout the world. During tumorigenesis, normal cells transform into tumour cells following changes in the expression of oncogenes and/or tumour suppressor genes, which are involved in many processes including the cell cycle, differentiation and apoptosis. An imbalance in the regulation of proliferation and differentiation in colon epithelial cells is usually associated with the development of colon cancers. Uncontrolled proliferation with a lack of differentiation is one of the major characteristic features of cancer cells and a remodelling of the Ca2+ signalling is linked to these pathways. Among the Ca2+ transporting proteins, P-type Ca2+-ATPases, the plasma membrane Ca2+ ATPase (PMCA) pump, has a high-affinity for Ca2+ and is involved in the efflux of Ca2+ against the electrochemical gradient from the cytosol across the extracellular space. Four PMCA isoforms have been identified. PMCA1 and 4 are expressed in most tissues. Changes in the expression of PMCA have been documented in breast cancer cells, whereas the expression profile of PMCA isoforms in colon cancer cells remains unknown. Up-regulation of another P-type Ca2+-ATPase, expressed in the endoplasmic reticulum, SERCA3, occurs during the differentiation of colon cancer cell lines and is down-regulated in colon cancers. Changes in PMCA expression have not been assessed during colon cancer cell differentiation. The first part of this thesis describes the analysis of the expression profile of PMCA during colon cancer cell differentiation. Both PMCA mRNA and protein levels were assessed in differentiated HT-29 cells by real time RT-PCR and western blotting analysis, respectively. The results showed changes in PMCA4 expression, whereas changes in the expression of PMCA1 were not associated with differentiation of HT-29 cells. PMCA mRNA levels were also reduced in some colon cancers suggesting a remodelling of PMCA-mediated Ca2+ efflux during colon carcinogenesis. The second part of this thesis involved exploring the functional role of PMCA4 in Ca2+-mediated signalling pathways such as differentiation, proliferation and apoptosis. PMCA4 expression was altered in HT-29 colon cancer cells via transient and stable over-expression of a PMCA4 expressing plasmid or siRNA-mediated silencing of PMCA4. An increase in the PMCA4 level did not alter or induce differentiation of HT-29 cells. Hence, up-regulation of PMCA4 expression may be a consequence rather than a cause of HT-29 colon cancer cell differentiation. PMCA4-mediated reduction in proliferation was observed in HT-29 colon cancer cells where PMCA4 was stably over-expressed. Stable PMCA4 over-expression was also associated with the down-regulation of the transcription of the early response gene, FOS. Despite the apparent augmentation of cytosolic Ca2+ responses to G-protein coupled receptor Ca2+ mobilizing agents, the sensitivity of cells to the apoptotic inducing agents such as TRAIL and/or CCCP was not affected following siRNA-mediated PMCA4 inhibition in HT-29 cells. Collectively this thesis describes PMCA isoform-specific changes during differentiation of HT-29 colon cancer cells and alterations in PMCA levels in some colon cancers.Evidence is also presented to suggest that alterations in PMCA expression in colon cancer cells may provide a growth advantage by promoting proliferation without increasing sensitivity to apoptotic stimuli.

There exists a profound need for biomarkers that will allow for better screening and risk stratification for colorectal cancer (CRC). With the advent of the newly termed "metabolic syndrome", CRC prevalence is trending upwards even with much improved screening protocols and remains the second leading cause of cancer related morbidity. The "metabolic syndrome" refers to a range of environmental risk factors, including diabetes and obesity, thought to be increasing the prevalence of CRC. An altered metabolism is seen in metabolic syndrome, which affects cancer through changes in the relationship between glycolysis, the Krebs cycle, and mitochondrial oxidative phosphorylation (OXPHOS). Specifically, it has been observed that highly proliferative tumorigenic cells are undergoing a shift away from the energy efficient OXPHOS and toward aerobic glycolysis even under normoxic conditions. This effect has been termed, the Warburg Effect. As a consequence of endogenous (e.g. genetic, diabetes etc.) and exogenous (e.g. diet, smoking etc.) factors, alterations in cell proliferation/death have been shown to occur throughout the colon reflecting the diffuse "field of injury" (field carcinogenesis). Also due to high energy demands it is recognized that the hyper-proliferative mucosa contiguous to colonic tumors may be hyper-metabolic. Our group has been interested in elucidating the biological nature of field carcinogenesis and assesses expression of key metabolic markers in the rectal biopsies from patients who harbor neoplasia elsewhere in their colon. We found key indications of a glycolytic shift toward aerobic glycolysis with upregulation of glucose transporter (GLUT1) as well as pyruvate shunting away from OXPHOS via pyruvate kinase muscle 2 (PKM2). These changes were further corroborated by an increase in hypoxia inducible factor 1 alpha (HIF1alpha), which is normally seen to increase glycolytic function in hypoxic conditions. Along with these glycolytic changes we also found mitochondrial dysfunction in patients with adenomas. Specifically, mitochondrial mass was found to be increased, with increases in mtDNA as well as upregulation of mitochondrial fusion via optic atrophy 1 (OPA1). Uncoupling protein 2, which decouples OXPHOS from ATP synthesis in the mitochondria, was also found to be upregulated. These findings represent a novel panel of biomarkers for assessing CRC risk via analysis of metabolic dysfunction in the easily accessible rectal epithelium.

Introdução - Estudos sobre o câncer de cólon mostram que a sua incidência, no mundo, tem aumentado de maneira significativa no último século. Acredita-se que este resultado esteja relacionado, entre outros aspectos, com a industrialização, a urbanização ocorridas neste período e mudanças no estilo de vida. A morbimortalidade associada ao câncer de cólon observada em países desenvolvidos é maior do que em países em desenvolvimento e o que se tem observado é que, embora a tendência da incidência seja crescente para ambos os sexos, a mortalidade permanece estável. Objetivo - Analisar as tendências da incidência e da mortalidade de pacientes com câncer de cólon, registrados no Registro de Câncer de Base Populacional (RCBP) do Município de São Paulo. Métodos - Foram analisadas as tendências temporais da incidência no período de 1997 a 2005 e da mortalidade no período de 1980 a 2007. As análises foram feitas separadamente por sexo e faixa etária e os efeitos da idade, do período e da coorte foram estimados através do modelo de regressão de Poisson. Resultados - Houve aumento na incidência por câncer de cólon no município de São Paulo, em quase todas as faixas etárias estudadas. O aumento da mortalidade foi menor do que o aumento da incidência e parece coincidir com um efeito de coorte presente durante todo o período do estudo. Tanto na incidência quanto na mortalidade, os aumentos foram mais pronunciados entre os homens. O modelo idade-período apresentou o melhor ajuste para os coeficientes de incidência para ambos os sexos, e o modelo completo (idade-período-coorte) se mostrou com melhor ajuste para os coeficientes de mortalidade para ambos os sexos. Não foi identificada interação estatisticamente significativa do sexo para os coeficientes de incidência e de mortalidade. Conclusão: Os resultados encontrados no presente estudo mostraram um aumento da incidência e da mortalidade, em ambos os sexos, em quase todas as faixas etárias. Observamos uma tendência da estabilização nas coortes de nascimento do câncer de cólon para ambos os sexos, sugerindo que as mudanças de estilo de vida podem contribuir para a redução da mortalidade por câncer de cólon, principalmente nas coortes mais jovens. / Introduction Studies on colon cancer show that its incidence worldwide has been increasing in the last century. There is evidence suggesting that this can be partially related to the industrialisation and urbanisation which occurred in the period and life style changes. Morbi-mortality associated with colon cancer observed in industrialised countries is greater than in developing countries. Colon cancer incidence presents an increasing trend for both sexes, probably due to a wider access to available diagnostic methods, while mortality rates remain stable. Objective: To assess incidence and mortality trends in patients with colon cancer, registered in São Paulo Cancer Registry. Methods: Temporal trends between 1997 and 2005 for incidence and between 1980 and 2007 for mortality were assessed. Analyses were performed separately by sex and age group, and effects of age, period and cohort were estimated by using Poisson´s regression model. Results: For all age groups assessed, there was an increase in colon cancer incidence in the city of São Paulo. The increase in mortality rates was lower than the increase in incidence which seems to coincide with a cohort effect present during the period studied. Increases in both incidence and mortality rates, were more pronounced among men. The age-period model presented the best adjustment to incidence coefficients for both sexes and the complete age-periodcohort model showed the best adjustment to mortality coefficients for both sexes. No significant statistical interaction for sex and incidence coefficient or sex and mortality coefficient was found. Conclusion: Results found in the present study revealed an increase in incidence and mortality rates, for both sexes and all age groups. A stabilisation in birth cohorts of colon cancer for both sexes was observed, suggesting that life style changes may contribute to the reduction in colon cancer mortality, especially in younger cohorts.

Colorectal cancer (CRC) has a 5-year survival rate of 68% yet it still has a mortality rate of 50,000 per year. While CRC has a host of causes, one that stands out is TGFβ deficient signaling, which is disrupted in a majority of high-microsatellite-instability or inflammation-associated CRCs. Since TGFβ is a multifunctional cytokine, it has been elusive to determine whether its effect on cancer development is operating through inflammation, differentiation or developmental pathways. Additionally, it is now becoming apparent that a great number of CRC cases can be associated with and possibly caused by gut bacteria dysbiosis. Here, I present a metagenomic and metatranscriptomic study of the interactions between TGFβ deficient signaling, inflammatory signaling, and the microbiome in a CRC mouse model. TGFβ deficient mice have reduced amounts of Firmicutes as well as mRNA counts of a key butyrate enzyme. Lack of butyrate, as shown by previous literature, could be inhibiting apoptosis and promoting growth. Also, TGFβ deficient mice have increased mRNA counts of polyamine producing genes, which could act synergistically with butyrate reduction. I find that H. hepaticus inoculation, as a source of inflammatory signaling, affects another species, M. schaedleri, to produce pro- inflammatory lipopolysaccharides. Additionally, H. hepaticus itself has increased oxidative phosphorylation; reactive oxygen species from this process could be adding to cancer-promoting DNA damage. Taken together, TGFβ deficient signaling and H. hepaticus inoculation, disrupt enough pathways to cross the threshold of carcinogenicity in 40% of the mice in our study. The results of this study emphasize the importance of microbiome function and represent possible new avenues of treatment.

Colorectal cancer is the second leading cause of cancer-related deaths in the United States and the third most common cancer in men and women. Vitamin E is a lipid soluble antioxidant that exists as eight structurally different isoforms of tocopherols and tocotrienols. Recent experimental, and molecular studies suggest that γ-tocotrienol (GT3) may be a more potent cancer-preventive form of vitamin E. 15-lipoxygenase-1 (15-LOX-1) and its product 13-S-hydroxyoctadecadienoic acid (13-S-HODE) are decreased in colon cancer cells. 15 LOX-1 is considered a tumor suppressor gene in colon carcinogenesis. Non-steroidal anti-inflammatory drug (NSAID)-induced 15-LOX-1 expression is critical to aspirin and NSAID-induced apoptosis in colorectal cancer cells. HCT-116 is a microsatellite-instability (MSI) colon cancer cell line. MSI is a marker of chemo-resistance but is associated with improved survival as compared to microsatellite-stable (MSS) colon cancers. The effects of GT3 on cytotoxicity and 15 LOX-1 expression was studied on the human colon cancer cell line HCT-116. HCT-116 colon cancer cell lines were cultured in DMEM media and dosed with increasing concentrations of GT3 (20µM-50µM). Cytotoxicity of the drugs was studied using Cell Titer Glo and MTS assays 24 hours after dosing. Cells were then plated in 6-well plates and grown for 24 hours. Cells were then dosed with 2 mL of GT3 at 20 uM at the respective time periods (2h, 4h, 6h, 12h, 16h, 24h) and lysates were harvested. Gel electrophoresis was run according to BCA protein assay from the time-dependent lysates and blots were tagged with a rabbit 15-lox antibody. Ongoing experiments include RNA PCR. RNA is being isolated at 2, 4, 6 and 12 hours. The RNA as reversed transcribed using a 15 lox 1 primer and that cDNA is being quantified using Quantitative PCR. GT3 induced cytotoxicity in MTS assay and Cell Titer Glo assay when added to HCT-116 cell line. 15 LOX 1 protein expression was found to be up-regulated in the colon cancer cell line HCT-116 when GT3 was added at 12h, 16h and 24h with the maximum expression at 16 hours. Chemotherapeutic drugs can have significant side effects. Understanding the role of GT3 on colon cancer cell lines could lead to the development of novel drugs to supplement current chemotherapy regimens and allow for lower doses of chemotherapeutic agents. Modulation of 15-LOX-1 suggests that GT3 may induce apoptosis through induction of the lipoxygenase pathway. Further experiments are under way to study the mechanism of action of GT3 on the 15 LOX-1 pathway. Since HCT-116 is a MSI- colon cancer cell line, effects of GT3 on MSS- colon cancer cell lines will also be studied.