Role In Development Of Colon Cancer Research Articles

N-acetyltransferase 10 promotes colon cancer progression by inhibiting ferroptosis through N4-acetylation and stabilization of ferroptosis suppressor protein 1 (FSP1) mRNA.

N-acetyltransferase 10 (NAT10) is the only enzyme known to mediate the N4-acetylcytidine (ac4C) modification of mRNA and is crucial for mRNA stability and translation efficiency. However, its role in cancer development and prognosis has not yet been explored. This study aimed to examine the possible role of NAT10 in colon cancer. The expression levels of NAT10 were evaluated by immunohistochemical analyses with a colon cancer tissue microarray, and its prognostic value in patients was further analyzed. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were performed to analyze NAT10 expression in harvested colon cancer tissues and cell lines. Stable NAT10-knockdown and NAT10-overexpressing colon cancer cell lines were constructed using lentivirus. The biological functions of NAT10 in colon cancer cell lines were analyzed in vitro by Cell Counting Kit-8 (CCK-8), wound healing, Transwell, cell cycle, and ferroptosis assays. Xenograft models were used to analyze the effect of NAT10 on the tumorigenesis and metastasis of colon cancer cells in vivo. Dot blotting, acetylated RNA immunoprecipitation-qPCR, and RNA stability analyses were performed to explore the mechanism by which NAT10 functions in colon cancer progression. NAT10 was upregulated in colon cancer tissues and various colon cancer cell lines. This increased NAT10 expression was associated with shorter patient survival. Knockdown of NAT10 in two colon cancer cell lines (HT-29 and LoVo) impaired the proliferation, migration, invasion, tumor formation and metastasis of these cells, whereas overexpression of NAT10 promoted these abilities. Further analysis revealed that NAT10 exerted a strong effect on the mRNA stability and expression of ferroptosis suppressor protein 1 (FSP1) in HT-29 and LoVo cells. In these cells, FSP1 mRNA was found to be modified by ac4C acetylation, and this epigenetic modification was associated with the inhibition of ferroptosis. Our study revealed that NAT10 plays a critical role in colon cancer development by affecting FSP1 mRNA stability and ferroptosis, suggesting that NAT10 could be a novel prognostic and therapeutic target in colon cancer.

Vitamin D receptor absence does not enhance intestinal tumorigenesis in ApcPirc/+rats.

ABSTRACTEpidemiological observations have prompted some to posit that elevated circulating vitamin D is responsible for reduced colon cancer in individuals residing near the equator. We have previously demonstrated that vitamin D has no effect on colon cancer in two rodent models of intestinal tumorigenesis. We have now extended this line of inquiry to ask whether ablation of vitamin D receptor (VDR) affects tumorigenesis. A VDR null rat was developed using Cas9-CRISPR technology, which allowed us to investigate whether 1,25(OH)D3 signaling through its receptor plays a role in intestinal tumorigenesis. Loss of VDR expression alone did not induce tumorigenesis, even in animals exposed to the inflammatory agent dextran sodium sulfate. These VDR−/− rats were then crossed with ApcPirc/+ rats, which are predisposed to the development of intestinal neoplasms. In combination with the Pirc/+ mutation, VDR loss did not enhance tumor multiplicity, growth, or progression in the colon or small intestine. This study demonstrates that the vitamin D receptor does not impact tumor development, and strongly supports previous findings that vitamin D itself does not play a role in colon cancer development or progression. Alternative explanations are needed for the original latitude hypothesis, as well as observational data in humans.This article has an associated First Person interview with the first author of the paper.

Immunocyte Profiling Using Single-Cell Mass Cytometry Reveals EpCAM+ CD4+ T Cells Abnormal in Colon Cancer.

Colon cancer (CC) is one of the leading causes of cancer related mortality. Research over past decades have profoundly enhanced our understanding of immunotherapy, a major clinical accomplishment, and its potential role toward treating CC. However, studies investigating the expression of these immune checkpoints, such as epithelial cell adhesion molecule (EpCAM), programmed death-1 (PD-1), and programmed death-ligand 1 (PD-L1), by peripheral blood mononuclear cells (PBMCs) is lacking. Here, high-dimensional mass cytometry (CyTOF) is used to investigate immune alterations and promising immunotherapeutic targets expression by PBMCs of CC patients. Results reveal that expression of EpCAM and PD-L1 on CD4+ T cells significantly increased in patients with CC, compared with age- and sex- matching healthy controls and patients with colonic polyps. These differences are also validated in an independent patient cohort using flow cytometry. Further analysis revealed that EpCAM+ CD4+ T cells are PD-L1+ CCR5+ CCR6+. Immunofluorescence staining results demonstrate that the increase of EpCAM+ CD4+ T cells is also observed in tumor tissues, rather than para-cancerous tissues. To ascertain the functional disorders of the identified cell subset, phosphorylated signaling protein levels are assessed using imaging mass cytometry. Increases in pp38 MAPK and pMAPKAPK2 are observable, indicating abnormal activation of pp38 MAPK-pMAPKAPK2 signaling pathway. Results in this study indicate that EpCAM+ CD4+ T cells may play a role in CC development. Detailed knowledge on the functionality of EpCAM+ CD4+ T cells is of high translational relevance.

The Colibactin Genotoxin Generates DNA Interstrand Cross-Links in Infected Cells.

ABSTRACTColibactins are hybrid polyketide-nonribosomal peptides produced by Escherichia coli, Klebsiella pneumoniae, and other Enterobacteriaceae harboring the pks genomic island. These genotoxic metabolites are produced by pks-encoded peptide-polyketide synthases as inactive prodrugs called precolibactins, which are then converted to colibactins by deacylation for DNA-damaging effects. Colibactins are bona fide virulence factors and are suspected of promoting colorectal carcinogenesis when produced by intestinal E. coli. Natural active colibactins have not been isolated, and how they induce DNA damage in the eukaryotic host cell is poorly characterized. Here, we show that DNA strands are cross-linked covalently when exposed to enterobacteria producing colibactins. DNA cross-linking is abrogated in a clbP mutant unable to deacetylate precolibactins or by adding the colibactin self-resistance protein ClbS, confirming the involvement of the mature forms of colibactins. A similar DNA-damaging mechanism is observed in cellulo, where interstrand cross-links are detected in the genomic DNA of cultured human cells exposed to colibactin-producing bacteria. The intoxicated cells exhibit replication stress, activation of ataxia-telangiectasia and Rad3-related kinase (ATR), and recruitment of the DNA cross-link repair Fanconi anemia protein D2 (FANCD2) protein. In contrast, inhibition of ATR or knockdown of FANCD2 reduces the survival of cells exposed to colibactin-producing bacteria. These findings demonstrate that DNA interstrand cross-linking is the critical mechanism of colibactin-induced DNA damage in infected cells.

Interleukin-37 mediates the antitumor activity in colon cancer through β-catenin suppression.

The occurrence and development of colon cancer is closely related to inflammation. Thus, we conducted the present retrospective study to investigate the effects of IL-37 (Interleukin 37), a newly identified anti-inflammatory factor, on colon cancer development. We first evaluated the IL-37 expression in 186 pairs of colon cancer samples and their adjacent normal mucosa by real-time PCR, ELISA (Enzyme-linked immunoassay) and tissue microarrays. Then the role of IL-37 on patient survival rates, colon cancer progression and their sensitivity to chemotherapy drugs were assessed. IL-37 was barely expressed in the colon cancer tissue but highly expressed in the adjacent normal tissue. The down-regulation of IL-37 was significantly correlated with the results of American Joint Committee on Cancer stage, nodal involvement, invasion depth, distant metastasis, differentiation and it was also shown to be an independent prognostic indicator of disease-free survival and overall survival for patients with colon cancer. Overexpression of IL-37 in colon cancer cell suppressed cell migration, invasion, proliferation, colony formation and cancer stem cells through suppressing β-catenin. IL-37 inhibited colon tumor formation in the mice model and sensitize the cancer cell to chemotherapy drugs. Our results showed that IL-37 plays an inhibitory role in colon cancer development and function as a novel prognostic indicator and a potential therapeutic target.

M2-like macrophages induce colon cancer cell invasion via matrix metalloproteinases.

The inflammatory milieu plays an important role in colon cancer development and progression. Previously, we have shown that tumor-associated macrophages (TAMs), an important component of the tumor microenvironment, are enriched in tumors compared with normal tissue and confer a poorer prognosis. In the present study, we found that matrix metallopeptidase-9 (MMP-9), which degrades extracellular matrix proteins, was increased in biopsies from colon cancer patients and in mouse xenografts with SW480 cell-derived tumors. SW480 colon cancer cells exposed to M2-like macrophage-conditioned medium (M2-medium) exhibited increased MMP-9 mRNA, protein expression and gelatinase activity. A similar effect was obtained by the addition of tumor necrosis factor-α (TNFα) and leukotriene D4 (LTD4 ). MMP-9 expression and activity were reduced by a TNFα blocking antibody adalimumab and a cysteinyl leukotriene receptor 1 (CysLTR1, the receptor for LTD4 ) antagonist montelukast. M2-medium also induced changes in the epithelial-mesenchymal transition (EMT) markers E-cadherin, β-catenin, vimentin, and snail in SW480 cells. We also found that both M2-medium and TNFα and LTD4 induced stabilization/nuclear translocation of β-catenin. Furthermore, we also observed an elongated phenotype that may indicate increased invasiveness, as confirmed in a collagen I invasion assay. M2-medium increased the invasive ability, and a similar effect was also obtained by the addition of TNFα and LTD4 . The specific MMP inhibitor I or adalimumab and montelukast reduced the number of invasive cells. In conclusion, our findings show that M2-medium enriched in TNFα and LTD4 promote colon cancer cell invasion via MMP-9 expression and activation and the induction of EMT.

MiR-19a promotes colitis-associated colorectal cancer by regulating tumor necrosis factor alpha-induced protein 3-NF-κB feedback loops.

Chronic inflammation is believed to have a crucial role in colon cancer development. MicroRNA (miRNA) deregulation is common in human colorectal cancers, but little is known regarding whether miRNA drives tumor progression by regulating inflammation. Here, we showed that miR-19a can promote colitis and colitis-associated colon cancer (CAC) development using a CAC mouse model and an acute colitis mouse model. Tumor necrosis factor-α (TNF-α) stimulation can increase miR-19a expression, and upregulated miR-19a can in turn activate nuclear factor (NF)-κB signaling and TNF-α production by targeting TNF alpha-induced protein 3 (TNFAIP3). miR-19a inhibition can also alleviate CAC in vivo. Moreover, the regulatory effects of miR-19a on TNFAIP3 and NF-κB signaling were confirmed using tumor samples from patients with colon cancer. These new findings demonstrate that miR-19a has a direct role in upregulating NF-κB signaling and that miR-19a has roles in inflammation and CAC.

Association between TLR-9 polymorphisms and colon cancer susceptibility in Saudi Arabian female patients.

ObjectiveThe authors aimed to explore the relationship between the expression/polymorphisms of TLR-9 and susceptibility to colon cancer development in the Saudi Arabian population.MethodsIn total, blood samples from 115 patients with colon cancer and 102 participants without colon cancer were analyzed in this study. Three single-nucleotide polymorphisms (SNPs) were selected from the TLR-9 gene, including two sites within the TLR-9 gene’s promoter region (rs352144 and rs187084) and one site in a TLR-9 intron region (rs5743839). Odds ratios (ORs) and 95% confidence intervals (CIs) were computed from logistic regression models after adjusting for age, gender, and tumor localization. To investigate the differential expression of TLR-9 in colon cancer, TLR-9 expression was evaluated using quantitative real-time reverse transcription polymerase chain reaction on 40 matched normal and colon tissues.ResultsThe authors found that TLR-9 expression was decreased in colon cancer tissues as compared with that in normal tissues. Moreover, significant associations between the TLR-9 rs187084 SNP and colon cancer risk were observed in female patients only. In rs187084, the T allele had a significantly lower frequency (2.8 times) in female cancer patients than in controls (0.27 vs 0.41). The TLR-9 rs352139 and rs352144 SNPs were significantly associated with colon cancer development when the tumor was located in the rectal area.ConclusionThe findings support the hypothesis that TLR-9 has an anticancer role in colon cancer development. Furthermore, genetic variation may influence colon cancer development, and SNPs in TLR-9 could serve as biomarkers for decision making in the treatment of females with rectal cancer.

Treadmill Exercise Decreases Aberrant Crypt Foci Lymph Associated in the Large Intestine of Obese Mice

Colorectal cancer is the third leading cancer for both incidence and mortality. Obesity increases risk of developing colorectal cancer. On the other hand, increased physical activity is associated with a decreased risk of a variety of cancers. However, mechanisms of how physical activity reduces risk of cancer development remain to be illustrated. We hypothesize that exercise reduces the risk of developing colon cancer in obese animals. The aim of our study was to understand how diet and exercise affect metabolism and colon cancer formation in a preclinical model. To test this, C57BL/6N mice were fed either a control diet, AIN‐93M, or a high fat (HF) diet consisting of 45% fat for 9 weeks followed by intraperitoneal injection of carcinogen Azoxymethane (AOM). Mice on HF diet were divided into two groups: high‐fat (HF) and high‐fat plus exercise (HF+EX). A 24‐week progressive treadmill‐training program (1 hr/d, 3 d/wk) was used to exercise the mice in the HF+EX group. At the end of the study, all colons were sampled for histological examination of aberrant crypt foci (ACF) development by methylene blue staining. As expected the HF group had more ACF compared to the control group (5.29 vs 3.93, p < 0.05), but was not statistically different from the HF+EX group (5.29 vs 6.11, p = 0.23). Interestingly, the HF+EX group had more lymph nodules in the colon epithelial surface than the HF and control group (37, 17, and 12, respectively, p < 0.05). This led to the observation that ACF found around lymphatic tissue were significantly less in the exercised HF+EX group compared to the non‐exercised HF group (0.25 vs 0.61, p < 0.05). In addition, qRT‐PCR analysis of gene expression in the liver showed that cMYC expression was lower in the HF+EX group compared to both the HF and control groups. Since cMYC is an oncogene that plays a role in glucose metabolism, mitochondrial biogenesis, lipid synthesis, and ribosome biogenesis, further analysis is done to determine the involvement of the various pathways in this mouse model of colon cancer. In summary, data from this study indicate that exercise may play a protective role in colon cancer development by increasing activity of the immune response through the development of lymphatic system in the colon and reducing the potential of ACF formation.

Abstract 5273: Role of methylation of Wnt target genes in tumorigenesis and effect of re-expression with demethylating agent decitabine in colon cancer

Abstract Colon cancer is the fourth leading cause of cancer-related death worldwide. Extensive studies of the Wnt signal cascade have determined its role in colon cancer development and progress. Several targets of the Wnt-cascade like APCDD1, ASCL2, AXIN2 or DKK1 are thought to reduce Wnt activity by negative feedback. As a result, expression of these genes prevents pathway activation and silencing of these targets can cause proliferation of the tumor. Recently, we have shown that silencing of Wnt target genes by DNA-methylation predicts poor prognosis in colon cancer patients. Moreover, demethylation of those genes results in reexpression and is associated with reduced tumor growth in mice. Hence, treatment with demethylating agents can be beneficial for a subgroup of colon cancer patients with high methylation of Wnt target genes. The aim of this study is to clarify whether Wnt target gene methylation is an important driver in development of colon cancer and can be an effective target in colon cancer. To determine the role of Wnt target genes in colon cancer more extensively, we study the effect of selective expression of these genes via an inducible vector system in established colorectal cell lines and in patient derived cultures that display CpG island methylation on these genes. In that way, we can monitor the effect of induced overexpression on tumor growth, tumor invasion and sensitivity towards chemotherapeutic agents. As a control, baseline expression in the same cell population, but in an uninduced state will be used. Furthermore, we are also studying the effect of the demethylating agent decitabine on Wnt target gene methylation in a clinical trial in stage II/III colon cancer patients. Patients are pre-operatively treated with decitabine. Tumor material prior to decitabine treatment obtained during endoscopy is compared to resection material after treatment. Differences in methylation and expression of Wnt target genes are determined by respectively pyrosequencing and q-PCR. We hypothesize that reexpression of Wnt target genes via an inducible vector results in lower Wnt pathway activity through negative feedback. As a result, tumor growth and invasion will be reduced and might be more sensitive towards chemotherapeutics. To translate this into the clinic, demethylation of Wnt target genes by decitabine will hopefully give a similar effect in patients. Citation Format: Janneke Linnekamp, Raju Kandimalla, Louis Vermeulen, Hanneke van Laarhoven, Jan Paul Medema. Role of methylation of Wnt target genes in tumorigenesis and effect of re-expression with demethylating agent decitabine in colon cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5273. doi:10.1158/1538-7445.AM2015-5273

Tubulin glycylases are required for primary cilia, control of cell proliferation and tumor development in colon.

TTLL3 and TTLL8 are tubulin glycine ligases catalyzing posttranslational glycylation of microtubules. We show here for the first time that these enzymes are required for robust formation of primary cilia. We further discover the existence of primary cilia in colon and demonstrate that TTLL3 is the only glycylase in this organ. As a consequence, colon epithelium shows a reduced number of primary cilia accompanied by an increased rate of cell division in TTLL3-knockout mice. Strikingly, higher proliferation is compensated by faster tissue turnover in normal colon. In a mouse model for tumorigenesis, lack of TTLL3 strongly promotes tumor development. We further demonstrate that decreased levels of TTLL3 expression are linked to the development of human colorectal carcinomas. Thus, we have uncovered a novel role for tubulin glycylation in primary cilia maintenance, which controls cell proliferation of colon epithelial cells and plays an essential role in colon cancer development.

Differential Regulation of EGFR–MAPK Signaling by Deoxycholic Acid (DCA) and Ursodeoxycholic Acid (UDCA) in Colon Cancer

A high-fat diet coincides with increased levels of bile acids. This increase in bile acids, particularly deoxycholic acid (DCA), has been strongly associated with the development of colon cancer. Conversely, ursodeoxycholic acid (UDCA) may have chemopreventive properties. Although structurally similar, DCA and UDCA present different biological and pathological effects in colon cancer progression. The differential regulation of cancer by these two bile acids is not yet fully understood. However, one possible explanation for their diverging effects is their ability to differentially regulate signaling pathways involved in the multistep progression of colon cancer, such as the epidermal growth factor receptor (EGFR)-mitogen-activated protein kinase (MAPK) pathway. This review will examine the biological effects of DCA and UDCA on colon cancer development, as well as the diverging effects of these bile acids on the oncogenic signaling pathways that play a role in colon cancer development, with a particular emphasis on bile acid regulation of the EGFR-MAPK pathway.

Colon cancer bears overexpression of OTUB1

ObjectiveOTUB1 is a member of deubiquitinating enzymes; however, its expression and function in colon cancer are still unclear. The present study aimed at investigating the expression of OTUB1 in colon cancer and the relationship between the expression and some clinicopathologic parameters. MethodsImmunohistochemistry and quantitative real-time PCR were carried out in selected colon cancer and normal mucosa tissues. ResultsThe expression of OTUB1 protein in the colon cancer was significantly higher than normal mucosa, and the OTUB1 mRNA in colon cancer was also 3.15-fold higher than the normal mucosa. The higher expression of OTUB1 in colon cancer was related with tumor size, differentiation and lymph node metastasis. ConclusionsOTUB1 may play an important role in colon cancer development and metastasis.

Long non-coding RNA HOTAIR is a powerful predictor of metastasis and poor prognosis and is associated with epithelial-mesenchymal transition in colon cancer.

Colon cancer is one of the most frequently diagnosed cancer and the third most fatal malignancy worldwide. HOTAIR, a cancer-associated long non-coding RNA (lncRNA), is a powerful biomarker of metastasis and poor prognosis in a diverse group of cancers. Nevertheless, an understanding of how HOTAIR is involved in colon cancer progression is limited. In the present study, we hypothesized that HOTAIR plays a crucial role in colon cancer development. We evaluated the expression of HOTAIR in 120 colon cancer samples, matched adjacent non-tumor mucosa and 32 lymph node metastasis tissues by real-time PCR. Increased HOTAIR expression was significantly correlated with the depth of tumor invasion, lymph node metastasis, organ metastasis, histological differentiation, vascular invasion and advanced tumor stage. Patients with high HOTAIR expression had higher recurrence rates and reduced metastasis-free and overall survival than patients with low HOTAIR expression. Moreover, our findings revealed that HOTAIR had a limited effect on cell proliferation but significantly promoted colon cancer cell migration and invasion in vitro. Depletion of HOTAIR increased the expression of E-cadherin while concomitantly decreasing expression of vimentin and MMP9. Hence, HOTAIR may be another pleiotropic modulator participating in epithelial-mesenchymal transition (EMT). These results indicate that HOTAIR may also be a valuable predictor for colon cancer management; furthermore, this lncRNA may be a potential target for cancer prevention and treatment.

MicroRNA-192 suppresses liver metastasis of colon cancer

Metastasis causes most deaths from colon cancer yet mechanistic understanding and therapeutic options remain limited. Here we show that expression of microRNA (miR)-192 is inversely correlated with metastatic potential of colon cancer cells. Ectopic expression of miR-192 sensitizes colon cancer cells to growth factor deprivation stress (GFDS)-induced apoptosis whereas inhibition of miR-192 confers resistance. Overexpression of miR-192 inhibits metastatic colonization to the liver in an orthotopic mouse model of colon cancer. Alterations associated with the metastatic phenotype in the primary tumors include increased apoptosis, decreased proliferation and angiogenesis. Further studies indicate that miR-192 down-regulates expression of Bcl-2, Zeb2 and VEGFA in vitro and in vivo, which is responsible for enhanced apoptosis, increased expression of E-cadherin and decreased angiogenesis in vivo respectively. Finally, studies performed on human colonic adenocarcinoma show that expression of miR-192 is significantly reduced in neoplastic cells as compared to normal colonic epithelium. Importantly, there is a significant decrease of miR-192 expression in stage IV tumors when compared to stage I or II lesions. These findings indicate that miR-192 plays an important role in colon cancer development and progression. Our studies underscore the clinical relevance and prognostic significance of miR-192 expression in colon cancer. Therefore, a major implication of our studies is that restoration of miR-192 expression or antagonism of its target genes (Bcl-2, Zeb2 or VEGFA) may have considerable therapeutic potential for anti-metastatic therapy in patients with colon cancer.

Brucine suppresses colon cancer cells growth via mediating KDR signalling pathway.

Angiogenesis plays an important role in colon cancer development. This study aimed to demonstrate the effect of brucine on tumour angiogenesis and its mechanism of action. The anti-angiogenic effect was evaluated on the chicken chorioallantoic membrane (CAM) model and tube formation. The mechanism was demonstrated through detecting mRNA and protein expressions of VEGFR2 (KDR), PKCα, PLCγ and Raf1 by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot (WB), as well as expressions of VEGF and PKCβ and mTOR by ELISA and WB. The results showed that brucine significantly reduced angiogenesis of CAM and tube formation, inhibited the VEGF secretion and mTOR expression in LoVo cell and down-regulated the mRNA and phosphorylation protein expressions of KDR, PKCα, PLCγ and Raf1. In addition, the effects of brucine on KDR kinase activity, viability of LoVo cell and gene knockdown cell were detected with the Lance™ assay, WST-1 assay and instantaneous siRNA. Compared to that of normal LoVo cells, the inhibition on proliferation of knockdown cells by brucine decreased significantly. These results suggest that brucine could inhibit angiogenesis and be a useful therapeutic candidate for colon cancer intervention.

A novel angiogenesis inhibitor impairs lovo cell survival via targeting against human VEGFR and its signaling pathway of phosphorylation

Colorectal cancer represents the fourth commonest malignancy, and constitutes a major cause of significant morbidity and mortality among other diseases. However, the chemical therapy is still under development. Angiogenesis plays an important role in colon cancer development. We developed HMQ18–22 (a novel analog of taspine) with the aim to target angiogenesis. We found that HMQ18–22 significantly reduced angiogenesis of chicken chorioallantoic membrane (CAM) and mouse colon tissue, and inhibited cell migration and tube formation as well. Then, we verified the interaction between HMQ18–22 and VEGFR2 by AlphaScreen P-VEGFR assay, screened the targets on angiogenesis by VEGF Phospho Antibody Array, validated the target by western blot and RNAi in lovo cells. We found HMQ18–22 could decrease phosphorylation of VEGFR2(Tyr1214), VEGFR1(Tyr1333), Akt(Tyr326), protein kinase Cα (PKCα) (Tyr657) and phospholipase-Cγ-1 (PLCγ-1) (Tyr771). Most importantly, HMQ18–22 inhibited proliferation of lovo cell and tumor growth in a human colon tumor xenografted model of athymic mice. Compared with normal lovo cells proliferation, the inhibition on proliferation of knockdown cells (VEGFR2, VEGFR1, Akt, PKCα and PLCγ-1) by HMQ18–22 decreased. These results suggested that HMQ18–22 is a novel angiogenesis inhibitor and can be a useful therapeutic candidate for colon cancer intervention.

High Fat Mixed Lipid Diet Modifies Protective Effects of Exercise on 1,2 Dimethylhydrazine Induced Colon Cancer in Rats

The aim of the present study was to evaluate the effect of long-term swimming exercise in conjunction with a high fat mixed lipid (HFML) diet on colon cancer (CC) development and lipid peroxidation in the large bowel. We used forty male Wistar rats, which were randomly divided into one control group and four cancer groups: sedentary and swimming groups fed a standard diet (LFCO) and sedentary and swimming groups fed an HFML diet. Corticosterone was determined during the experiment. After 6 months of swimming, the rats were sacrificed and blood, heart, liver, muscle and large bowel were taken for determining the activity of serum enzymes, antioxidant capacity and CC development. The results demonstrate that exercise has a protective role in CC development. Attenuated development of CC and increased levels of malondialdehyde (MDA) in the large bowel of exercised rats show that one of the protective effects of exercise on developing CC is induction of oxidative stress. However, in terms of the combined effects of dietary fat and exercise, our results indicate that the protective role of exercise on CC development is significantly depressed by an HFML diet. An HFML diet significantly reduced the protective influence of exercise on colon carcinogenesis in rats and affected the degree of peroxidation in the large bowel during exercise, as well as concentrations of serum enzymes (LDH, α-HBDH, CK, ALT and AST). Our results indicate that an HFML diet, which reflects the composition of a Western style diet, is a significant modifier of the protective effects of exercise on CC development in rats.

Over-expression of GAPDH in human colorectal carcinoma as a preferred target of 3-Bromopyruvate Propyl Ester

It has long been observed that many cancer cells exhibit increased aerobic glycolysis and rely more on this pathway to generate ATP and metabolic intermediates for cell proliferation. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key enzyme in glycolysis and has been known as a housekeeping molecule. In the present study, we found that GAPDH expression was significantly up-regulated in human colorectal carcinoma tissues compared to the adjacent normal tissues, and also increased in colon cancer cell lines compared to the non-tumor colon mucosa cells in culture. The expression of GAPDH was further elevated in the liver metastatic tissues compared to the original colon cancer tissue of the same patients, suggesting that high expression of GAPDH might play an important role in colon cancer development and metastasis. Importantly, we found that 3-bromopyruvate propyl ester (3-BrOP) preferentially inhibited GAPDH and exhibited potent activity in inducing colon cancer cell death by causing severe depletion of ATP. 3-BrOP at low concentrations (1-10 μM) inhibited GAPDH and a much higher concentration (300 μM) was required to inhibit hexokinase-2. The cytotoxic effect of 3-BrOP was associated with its inhibition of GAPDH, and colon cancer cells with loss of p53 were more sensitive to this compound. Our study suggests that GAPDH may be a potential target for colon cancer therapy.

Dietary supplementation of resveratrol suppresses colonic tumour incidence in 1,2-dimethylhydrazine-treated rats by modulating biotransforming enzymes and aberrant crypt foci development

Diet-induced changes in the activities of bacterial enzymes are known to play a role in colon cancer development. Resveratrol has been implicated as a protective agent in carcinogenesis. In the present study, the effect of resveratrol on the activities of faecal and colonic biotransforming enzymes such as beta-glucuronidase, beta-glucosidase, beta-galactosidase, mucinase, nitroreductase and faecal sulfatase activity was assessed. The total number of aberrant crypt foci and their distribution in the proximal, medial and distal colon were observed in 1,2-dimethylhydrazine (DMH)-induced rats (group 3) and other treatment groups (groups 4-6). DMH (0.02 g/kg body weight) was given subcutaneously once a week for 15 consecutive weeks, and the experiment was terminated at 30 weeks. DMH-treated rats showed elevated levels of cancer-associated bacterial enzyme activities, whereas on resveratrol supplementation in three different regimens, rats showed lowered activities. Resveratrol supplementation throughout the experimental period (group 6) exerted a more pronounced effect (P < 0.01) by modulating the development of aberrant crypt foci and the activities of bacterial enzymes than did the other treatment regimens (groups 4 and 5). Thus, the present results demonstrate the inhibitory effect of resveratrol on DMH-induced colon carcinogenesis in rats.