Distal bowel selectivity in the chemoprevention of experimental colon carcinogenesis by the non-steroidal anti-inflammatory drug nabumetone

Prediction of death probability in adenocarcinoma of the transverse colon: competing-risk nomograms based on 21,469 patients

PURPOSE

Tumors in parts of the colon other than the transverse colon have been well studied, but little is known about adenocarcinoma of the transverse colon (ATC).The aim of this study was to construct nomograms using competing-risk model for accurately predicting the probability of cancer-specific and non-cancer-specific death in patients with ATC.

METHODS

Data on eligible patients recorded during 2000-2019 in the Surveillance, Epidemiology, and End Results database were extracted and screened. Factors that influencing prognosis were screened for death from ATC (DATC) and death from other causes (DOC) using competing-risk analysis, including univariate and multivariate analyses based on Gray's test and the Fine-Gray model, respectively. Independent prognostic factors were identified and nomograms were constructed. For comparison, we also constructed a Cox model and an AJCC stage-only competing-risk model (AJCC model) for patients with DATC. Performance evaluations of the nomograms and comparison between the models were performed using calibration plots, Harrell's concordance index (C-index), receiver operating characteristic (ROC) curves, and the areas under the ROC curve (AUCs). The nomograms and models were validated using a validation cohort. The net reclassification index, integrated discrimination improvement, decision curves, and risk stratification were not assessed because no accepted methods were suited for competing-risk model.

RESULTS

This study included 21,469 patients with ATC, and 17 and 9 independent influencing factors were identified for the construction of DATC nomograms (DATCN) and DOC nomograms (DOCN), respectively. In both the training and validation cohorts, the calibration curves indicated good agreement between the nomogram-based predictions and the actual observations in the two nomograms, respectively. The C-index of the DATCN was higher than 80% (80.3-83.3%) at 1, 3 and 5 years in both the training and validation cohorts, significantly outperforming the AJCC (76.7-78%) and Cox (75.4-79.5%) model. The C-index of the DOCN was also higher than 69% (69.0-73.6%). In terms of ROC curves at each time point, those of the DATCN were very close to the upper-left corner of the coordinate axis in both the training and validation cohorts, and their AUCs were larger than 84% (84.2-85.4%).The AUCs of the AJCC (78.4-81.1%) and Cox (79.4-81.5%) models were significantly lower (p < 0.05), and the curves were closer to the diagonal. The ROC curves of the DOCN was similar to those of the DATCN, and the AUCs were 68.5-74%. The DATCN and DOCN therefore had good consistency, accuracy, and stability, respectively.

CONCLUSION

This study was the first to construct competing-risk nomograms for ATC. These nomograms have proved useful for accurately assessing patient prognoses and allowing more-individualized follow-up strategies, thereby reducing the mortality.

Effective holistic characterization of small molecule effects using heterogeneous biological networks

The two most common reasons for attrition in therapeutic clinical trials are efficacy and safety. We integrated heterogeneous data to create a human interactome network to comprehensively describe drug behavior in biological systems, with the goal of accurate therapeutic candidate generation. The Computational Analysis of Novel Drug Opportunities (CANDO) platform for shotgun multiscale therapeutic discovery, repurposing, and design was enhanced by integrating drug side effects, protein pathways, protein-protein interactions, protein-disease associations, and the Gene Ontology, and complemented with its existing drug/compound, protein, and indication libraries. These integrated networks were reduced to a "multiscale interactomic signature" for each compound that describe its functional behavior as vectors of real values. These signatures are then used for relating compounds to each other with the hypothesis that similar signatures yield similar behavior. Our results indicated that there is significant biological information captured within our networks (particularly via side effects) which enhance the performance of our platform, as evaluated by performing all-against-all leave-one-out drug-indication association benchmarking as well as generating novel drug candidates for colon cancer and migraine disorders corroborated via literature search. Further, drug impacts on pathways derived from computed compound-protein interaction scores served as the features for a random forest machine learning model trained to predict drug-indication associations, with applications to mental disorders and cancer metastasis highlighted. This interactomic pipeline highlights the ability of Computational Analysis of Novel Drug Opportunities to accurately relate drugs in a multitarget and multiscale context, particularly for generating putative drug candidates using the information gleaned from indirect data such as side effect profiles and protein pathway information.

Associations of Novel Lifestyle- and Whole Foods-Based Inflammation Scores with Incident Colorectal Cancer Among Women

BACKGROUND

Chronic inflammation, associated with lifestyle and dietary factors, may contribute to colorectal carcinogenesis. To address this, we investigated associations of previously validated, inflammation biomarker panel-weighted, novel, 4-component lifestyle (LIS) and 19-component predominately whole foods-based dietary (DIS) inflammation scores with incident colorectal cancer (CRC) in the prospective Iowa Women's Health Study (IWHS; 1986-2012; n = 34,254, of whom 1,632 developed CRC).

METHODS

We applied the published scores' components' weights, summed the weighted components to constitute the scores (higher scores reflect a higher balance of pro-inflammatory exposures), and investigated LIS- and DIS-CRC associations using multivariable Cox proportional hazards regression.

RESULTS

The multivariable-adjusted hazards ratios (HR) and their 95% confidence intervals (CI) for CRC among participants in the highest relative to the lowest LIS and DIS quintiles were 1.47 (1.26, 1.72; P_trend < 0.01) and 1.07 (0.91, 1.25; P_trend = 0.22), respectively. The corresponding findings for distal colon cancers were HR 1.78 (1.29, 2.47) and HR 1.34 (0.98, 1.84), respectively. Among those in the highest relative to the lowest joint LIS/DIS quintile, the HR for CRC was 1.60 (95% CI 1.30, 1.98).

CONCLUSIONS

Our results suggest that a more pro-inflammatory lifestyle, alone and jointly with a more pro-inflammatory diet, may be associated with higher CRC risk.

A hybrid systems biology and systems pharmacology investigation of Zingerone's effects on reconstructed human epidermal tissues

Background

As individuals live longer, elderly populations can be expected to face issues. This pattern urges researchers to investigate the aging concept further to produce successful anti-aging agents. In the current study, the effects of Zingerone (a natural compound) on epidermal tissues were analyzed using a bioinformatics approach.

Methods

For this purpose, we chose the GEO dataset GSE133338 to carry out the systems biology and systems pharmacology approaches, ranging from identifying the differentially expressed genes to analyzing the gene ontology, determining similar structures of Zingerone and their features (i.e., anti-oxidant, anti-inflammatory, and skin disorders), constructing the gene-chemicals network, analyzing gene-disease relationships, and validating significant genes through the evidence presented in the literature.

Results

The post-processing of the microarray dataset identified thirteen essential genes among control and Zingerone-treated samples. The procedure revealed various structurally similar chemical and herbal compounds with possible skin-related effects. Additionally, we studied the relationships of differentially expressed genes with skin-related diseases and validated their direct connections with skin disorders the evidence available in the literature. Also, the analysis of the microarray profiling dataset revealed the critical role of interleukins as a part of the cytokines family on skin aging progress.

Conclusions

Zingerone, and potentially any constituents of Zingerone (e.g., their similar compound scan functionality), can be used as therapeutic agents in managing skin disorders such as skin aging. However, the beneficial effects of Zingerone should be assessed in other models (i.e., human or animal) in future studies.

Aberrant crypt foci are regionally affected by zinc treatment in a 1,2-dimethylhydrazine induced colon carcinogenesis model

Zinc is a trace element widely known for its marked antioxidant properties. To gain more insight into the site- and time- specific mechanisms by which it induces chemoprevention, this study was elaborated over a pre-cancerous model of colon carcinogenesis. Colon cancer was induced by 1,2-dimethylhydrazine (DMH) in mice (20 mg/kg for 2 weeks) and groups of animals were supplemented with or without zinc sulfate (ZnSO₄, 200 mg/L) in drinking water for 4, 10 or 14 weeks. Colon tissues were collected for pathological observation, analyzing aberrant crypt (AC) and aberrant crypt foci (ACF) formations, multiplicity and distribution. Similarly, histological assessment and mucin production, as well as oxidative stress markers estimation was performed for the different groups. Results showed a significant increase in ACF and AC numbers, ACF multiplicity and demonstrated stronger distal occurrence than in the proximal after DHM administration. Histopathological analysis presented marked structural alterations and mucin loss in the distal than the proximal colons. A significant increase in myeloperoxidase (MPO), nitric oxide (NO), L-ornithine and malondialdehyde (MDA) levels was observed followed by a significant decrease in antioxidant markers (superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH)). Oral ZnSO₄ supplementation (continuous or partial) induced significant decrease in ACF, AC numbers and multiplicity, restored histological architecture and mucin production, and a significant decrease in proinflammatory markers while it reduced antioxidants to normal levels. From this study, insight was obtained on the use of ZnSO₄ as a chemopreventive agent and shed light on its potential, as a supplement in nutraceutical approaches.

Effect of carcinogen 1,2-dimethylhydrazine treatment on fiber types in skeletal muscles of male Wistar rats

The cancerogen 1,2-dimethylhydrazine (DMH), widely used in the experimental animal model of carcinogenesis, affects various organs, but its effect on muscle fibers is unknown. To evaluate the effect of 15-week DMH treatment on the fiber size and myosin heavy chain (MyHC) isoforms, which substantially determine fiber types and their contractile characteristics, pure and hybrid fiber types were immunohistochemically determined according to the MyHC isoform expression in soleus, extensor digitorum longus, gastrocnemius medialis and lateralis muscles of DMH-treated and control male Wistar rats. Whereas the size of fibers was mostly unaffected, the MyHC isoform expression was partially affected in both gastrocnemius samples, but not in the soleus and extensor digitorum longus of DMH-treated rats. The lower proportions of hybrid fiber types and especially that of type 1/2x in most gastrocnemius samples of DMH-treated rats resulted in a shift towards a single MyHC isoform expression, but the extent and pattern of the MyHC isoform shift varied across the different gastrocnemius samples. Such variable response to DMH treatment across muscles indicates that each muscle possesses its own adaptive range. These findings are essential for an accurate evaluation of skeletal muscle characteristics in DMH animal model.

Effects of 5-Amyno-4-(1,3-benzothyazol-2-yn)-1-(3-methoxyphenyl)-1,2-dihydro-3H-pyrrol-3-one Intake on Digestive System in a Rat Model of Colon Cancer

Introduction. Pyrrol derivate 5-amyno-4-(1,3-benzothyazol-2-yn)-1-(3-methoxyphenyl)-1,2-dihydro-3H-pyrrol-3-one (D1) has shown antiproliferative activities in vitro, so investigation of the impact of D1 intake on gut organs in rats that experienced colon cancer seems to be necessary. Materials and Methods. D1 at the dose of 2.3 mg/kg was administered per os daily for 27 (from the 1st day of experiment) or 7 (from the 21st week of experiment) weeks to rats that experienced 1,2-dimethylhydrazine (DMH)-induced colon cancer for 20 weeks. 5-Fluorouracil (5FU) was chosen as reference drug and was administered intraperitoneally weekly for 7 weeks (from the 21st week of experiment) at the dose of 45 mg/kg. Results. Antitumor activity of D1 comparable with the 5FU one against DMH-induced colon cancer in rats was observed (decrease of tumor number and tumor total area up to 46%). D1 attenuated the inflammation of colon, gastric and jejunal mucosa, and the liver, caused by DMH, unlike 5FU, aggravating the latter. In addition, D1 partially normalized mucosa morphometric parameters suggesting its functional restore. Conclusions. D1 possesses, comparable with 5-fluorouracil antitumor efficacy, less damaging effects on the tissues beyond cancerous areas and contributes to partial morphological and functional gut organs recovery.

Deficiency of caveolin-1 in Apc(min/+) mice promotes colorectal tumorigenesis

Caveolin-1 (Cav1), a scaffold protein of membrane caveolae and coactivator of peroxisome proliferator-activated receptor gamma (PPARg), inhibits oncogenic signaling through Ras and wingless. However, the in vivo role of Cav1 in colorectal cancer (CRC) remained unknown. To test whether loss of Cav1 accelerates tumorigenesis, we generated a novel mouse model of CRC by crossing C57BL/6 Apc(min/+) with B6129 Cav1 knockout (Cav1-/-) mice. Apc(min/+) Cav1-/- mice developed large, microinvasive and vascularized intraepithelial adenocarcinomas in the distal colon and rectum with higher incidence than Apc(min/+) Cav1+/- and Apc(min/+) Cav1+/+ littermates. Intratumoral gene signatures related to Ras and wingless signaling were elevated, nuclear localization of PPARg protein and expression of PPARg-target genes were reduced independently of Cav1. The PPARg-agonist rosiglitazone prevented tumor formation in mice irrespectively of the Cav1 status and upregulated expression of the Ras-inhibitory protein docking protein-1. Thus, codeficiency of Cav1 and adenomatous polyposis coli facilitated formation of CRC, and activation of PPARg may offer novel strategies for treatment of CRC.

The role of peroxisome proliferator-activated receptors in carcinogenesis and chemoprevention

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that are involved in regulating glucose and lipid homeostasis, inflammation, proliferation and differentiation. Although all of these functions might contribute to the influence of PPARs in carcinogenesis, there is a distinct need for a review of the literature and additional experimentation to determine the potential for targeting PPARs for cancer therapy and cancer chemoprevention. As PPAR agonists include drugs that are used for the treatment of metabolic diseases, a more complete understanding of the roles of PPARs in cancer will aid in determining any increased cancer risk for patients undergoing therapy with PPAR agonists.

Morphological and molecular alterations in 1,2 dimethylhydrazine and azoxymethane induced colon carcinogenesis in rats

The dimethyhydrazine (DMH) or azoxymethane (AOM) model is a well-established, well-appreciated, and widely used model of experimental colon carcinogenesis. It has many morphological as well as molecular similarities to human sporadic colorectal cancer (CC), which are summarized and discussed in this paper. In addition, the paper combines present knowledge of morphological and molecular features in the multistep development of CC recognized in the DMH/AOM rat model. This understanding is necessary in order to accurately identify and interpret alterations that occur in the colonic mucosa when evaluating natural or pharmacological compounds in DMH/AOM rat colon carcinogenesis. The DMH/AOM model provides a wide range of options for investigating various initiating and environmental factors, the role of specific dietary and genetic factors, and therapeutic options in CC. The limitations of this model and suggested areas in which more research is required are also discussed.

Cyclo-oxygenase 2 inhibitor, nabumetone, inhibits proliferation in chronic myeloid leukemia cell lines

The anti-tumor effect of cyclo-oxygenase (COX) inhibitors has been documented in several studies. COX2 inhibitors have attracted more attention because of the fewer side-effects and the more prominent anti-tumor effects. However, experience with these drugs in hematological malignancies is limited. In our study, a potent COX2 inhibitor, nabumetone (NBT), was investigated for its anti-proliferative and apoptotic effects in K-562 and Meg-01 chronic myeloid leukemia blastic cell lines as a single agent or in combination with adriamycin (ADR) and interferon alpha (IFN-a). In these cell lines, a dose-dependent inhibition of proliferation was observed with NBT. We observed no significant apoptotic effect of NBT. However, NBT potentiated the apoptotic effect of ADR in the K-562 cell line. Bcl-2 expression was reduced by NBT (11% vs. 2%). The combination of NBT with IFN did not have any significant effect on the K-562 cell line. We suggest that NBT inhibits proliferation and potentiates the apoptotic effect of ADR in chronic myeloid leukemia cell lines.

Inducible nitric oxide synthase (iNOS) mediates the early increase of blood supply (EIBS) in colon carcinogenesis

We have recently demonstrated that dramatic alteration in mucosal microvascular blood content termed early increase in blood supply (EIBS) is a hallmark of early colon carcinogenesis. In the current study, we elucidate the mechanism of EIBS by assessing iNOS/nitric oxide axis in the histologically normal colonic mucosa of rats treated with the colon-specific carcinogen, azoxymethane. We demonstrate that there was a strong temporal correlation between EIBS and iNOS expression/activity. Importantly, we also observed that short-term treatment with nitric oxide inhibitor abrogated EIBS. These data indicate that iNOS induction may have a critical role in augmenting the predysplastic mucosal blood supply and thereby fostering colon carcinogenesis.

Effect of dietary apigenin on colonic ornithine decarboxylase activity, aberrant crypt foci formation, and tumorigenesis in different experimental models

The efficacy of dietary apigenin, a dietary flavonoid, in colon cancer prevention was investigated by evaluating the inhibition of the ornithine decarboxylase (ODC) activity and the formation of aberrant crypt foci (ACF) and by studying the ability of apigenin to block colon carcinogenesis in two mouse models. First, the activity of ODC was measured in colon cancer cells (Caco-2) and in the colon epithelium of CF-1 mice. Apigenin at 10 and 30 muM significantly inhibited the ODC activity of Caco-2 cells by 26% and 57%, respectively. Colonic ODC activity in CF-1 mice was reduced with 0.1% dietary apigenin by 42% compared with the control, but this difference was not statistically significant. Second, ACF formation was evaluated in azoxymethane (AOM)-induced CF-1 mice. Female CF-1 mice at 6 wk of age were i.p. injected with 5 mg/kg body weight (BW) AOM once to induce ACF. ACF formation in CF-1 mice was reduced by 50% (P < 0.05) with 0.1% dietary apigenin fed for 6 wk when compared with the control. Dietary apigenin inhibited ACF only in the distal region of the CF-1 mouse colon. Finally, tumorigenesis studies were conducted using two different mouse models: AOM-induced CF-1 mice and Min mice with mutant adenomatous polyposis coli (APC) gene. Female CF-1 mice at 6 wk of age were i.p. injected with 10 mg/kg BW AOM weekly for 6 (AOM Study I) or 4 (AOM Study II) wk to induce tumors. CF-1 mice were fed diets containing 0.025% or 0.1% apigenin for 23-25 wk. Female Min mice were fed diets for 10 wk beginning at 5 wk of age. In two AOM-treated mouse colon tumor studies 0.025% and 0.1% dietary apigenin modestly reduced tumors in the group fed 0.025% apigenin (25% incidence in comparison with 65% in the controls) in a non-dose response manner. Apigenin failed to inhibit adenoma formation in the Min mouse study. These results suggest that dietary apigenin showed promise in cancer prevention by reducing the ODC activity and ACF formation, however, clear evidence of cancer prevention was not obtained in mouse tumor studies. Further investigation of the potential chemopreventive effect of apigenin in carcinogenesis is warranted.

Celecoxib treatment alters the gene expression profile of normal colonic mucosa

A clinical trial was recently conducted to evaluate the safety and efficacy of a selective inhibitor of cyclooxygenase-2 (celecoxib) in hereditary nonpolyposis colon cancer patients. In a randomized, placebo-controlled phase I/II multicenter trial, hereditary nonpolyposis colon cancer patients and gene carriers received either celecoxib at one of two doses or placebo. The goal was to evaluate the effects of these treatment arms on a number of endoscopic and tissue-based biomarker end points after 12 months of treatment. As part of this trial, we analyzed gene expression by cDNA array technology in normal descending (rectal) colonic mucosa of patients before and after treatment with celecoxib or placebo. We found that treatment of patients with celecoxib at recommended clinical doses (200 and 400 mg p.o. bid), in contrast to treatment with placebo, leads to changes in expression of >1,400 genes in the healthy colon, although in general, the magnitude of changes is <2-fold. Twenty-three of 25 pairs of colon biopsies taken before and after celecoxib treatment can be classified correctly by the pattern of gene expression in a leave-one-out cross-validation. Immune response, particularly T- and B-lymphocyte activation and early steps of inflammatory reaction, cell signaling and cell adhesion, response to stress, transforming growth factor-beta signaling, and regulation of apoptosis, are the main biological processes targeted by celecoxib as shown by overrepresentation analysis of the distribution of celecoxib-affected genes across Gene Ontology categories. Analysis of possible cumulative effects of celecoxib-induced changes in gene expression indicates that in healthy colon, celecoxib may suppress the immune response and early steps of inflammation, inhibit formation of focal contacts, and stimulate transforming growth factor-beta signaling.

PPARdelta status and mismatch repair mediated neoplasia in the mouse intestine

Background

Therapeutic regulation of PPARδ activity using selective agonists has been proposed for various disorders. However, the consequences of altered peroxisome proliferator-activated receptor delta (PPARδ) activity in the context of intestinal tumourigenesis remain somewhat unclear. Contradictory evidence suggesting PPARδ either attenuates or potentiates intestinal neoplasia. To further investigate the PPARδ dependency of intestinal tumourigenesis, we have analysed the consequences of PPARδ deficiency upon intestinal neoplasia occurring in mice with impaired mismatch DNA repair.

Methods

Mice deficient for both PPARδ and the mismatch repair gene Mlh1 were produced and the incidence and severity of intestinal neoplasia recorded.

Results

No significant differences between the control genotypes and the double mutant genotypes were recorded indicating that deficiency of PPARδ does not modify impaired mismatch repair induced neoplasia.

Conclusion

In contrast with the previously observed acceleration of intestinal neoplasia in the context of the Apc^Min/+ mouse, PPARδ deficiency does not alter the phenotype of mismatch repair deficiency. This data supports the notion that PPARδ is not required for adenoma formation and indicate that any pro-tumourigenic effect of PPARδ inactivation may be highly context dependent.

Role of cyclooxygenase-2 in the carcinogenesis of gastrointestinal tract cancers: A review and report of personal experience

Selective cyclooxygenase (COX)-2 inhibitors (coxibs) were developed as one of the anti-inflammatory drugs to avoid the various side effects of non-steroidal anti-inflammatory drugs (NSAIDs). However, coxibs also have an ability to inhibit tumor development of various kinds the same way that NSAIDs do. Many experimental studies using cell lines and animal models demonstrated an ability to prevent tumor proliferation of COX-2 inhibitors. After performing a randomized study for polyp chemoprevention study in patients with familial adenomatous polyposis (FAP), which showed that the treatment with celecoxib, one of the coxibs, significantly reduced the number of colorectal polyps in 2000, the U.S. Food and Drug Administration (FDA) immediately approved the clinical use of celecoxib for FAP patients. However, some coxibs were recently reported to increase the risk of serious cardiovascular events including heart attack and stroke. In this article we review a role of COX-2 in carcinogenesis of gastrointestinal tract, such as the esophagus, stomach and colorectum, and also analyze the prospect of coxibs for chemoprevention of gastrointestinal tract tumors.

Quantitative analysis of PPARdelta mRNA by real-time RT-PCR in 86 rectal cancer tissues

AIM

The purpose of this study is to clarify the expression change of PPARdelta gene in human colorectal cancer tissues.

METHODS

Applying real-time RT-PCR, we quantified PPARdelta mRNA in a series of 86 tissues from excised primary rectal cancers. In each case, accompanying normal mucosa was collected for comparison.

RESULTS

Among the 86 rectal cancer tissues, 48 cases showed PPARdelta overexpression: 39 tumours gave an expression level 1.5-5 times, five tumours 10-20 times, and four tumours more than 20 times relative to normal mucosa. However, the general level of PPARdelta mRNA in rectal cancer tissues is not statistically different from normal mucosa.

CONCLUSIONS

The expression of PPARdelta gene in rectal cancers is not statistically different from normal mucosa.

Spectral markers in preneoplastic intestinal mucosa: an accurate predictor of tumor risk in the MIN mouse

BACKGROUND

We have reported recently that microarchitectural analysis of the histologically normal mucosa using a novel optics technology, four-dimensional elastic light scattering fingerprinting (ELF), provided unprecedented sensitivity for early detection of colon carcinogenesis. In the present study, we explored the ability of four-dimensional ELF to identify an inherited predisposition to colorectal cancer, an issue of considerable importance for optimizing population screening strategies.

METHODS

We used the MIN mouse, a model whose germ line adenomatous polyposis coli truncation leads to spontaneous intestinal tumorigenesis, thus replicating the human syndrome, familial adenomatous polyposis. Spectral markers were assessed by four-dimensional ELF analysis in MIN mice at preneoplastic time points and compared with age-matched controls (C57BL6 mice with wild-type adenomatous polyposis coli). To assess the responsiveness of spectral markers to chemopreventive agents, a subset of MIN mice was supplemented with celecoxib 1,500 ppm.

RESULTS

Spectral slope, fractal dimension, and principal component 3 were dramatically altered in the uninvolved MIN mouse mucosa at the earliest time points. Furthermore, alteration in spectral variables increased over time, consonant with the microarchitectural underpinnings of subsequent tumorigenesis. Additionally, these markers spatially correlated with future adenoma development (small intestine > colon). Short-term treatment with the potent chemopreventive agent, celecoxib, resulted in near normalization of fractal dimension and principal component 3.

CONCLUSIONS

We report, for the first time, that spectral markers, assayed by four-dimensional ELF, were able to sensitively identify a genetic predisposition for intestinal tumorigenesis before the occurrence of phenotypic manifestations. Moreover, the reversal of spectral markers by celecoxib treatment supports the neoplastic relevance.

Differential expression of COX-1 and COX-2 in the gastrointestinal tract of the rat

The aim of this study was to use immunohistochemistry with morphometry to investigate COX-1 and COX-2 expression in the normal rat gastrointestinal (GI) tract and examine if sites of ulceration previously observed with long-term COX-2 inhibitor administration in mice correlate with differential COX-1/COX-2 expression. COX-2 positive cells were observed predominantly in the apical lamina propria of intestinal villi with fewer cells in the mucosal epithelium. The highest level of COX-2 expression was observed at the ileocaecal junction (ICJ). COX-2 expression was also present in parasympathetic ganglia of the submucosa and muscularis. In the stomach, the highest grade of COX-2 expression was observed in the apical lamina propria of the fundus adjacent to the junctional ridge. In contrast, COX-1 positive cells within the lamina propria were evenly distributed along the GI tract but were present in higher numbers than COX-2 positive cells. The mean level of COX-1 expression at the ICJ was not significantly different from the ileum and caecum. Evidence that the highest level of COX-2 expression in normal rats is located on the ileal side of the ICJ provides the first mechanism to explain spontaneous ulceration and perforation of the distal ileum in COX-2 -/- animals.

The nonsteroidal anti-inflammatory drug, nabumetone, differentially inhibits beta-catenin signaling in the MIN mouse and azoxymethane-treated rat models of colon carcinogenesis

The mechanisms through which beta-catenin signaling is inhibited during colorectal cancer chemoprevention by nonsteroidal anti-inflammatory agents is incompletely understood. We report that nabumetone decreased uninvolved intestinal mucosal beta-catenin levels in the MIN mouse with a concomitant increase in glycogen synthase kinase (GSK)-3beta levels, an enzyme that targets beta-catenin for destruction. However, in the azoxymethane-treated rat, where beta-catenin is frequently rendered GSK-3beta-insensitive, nabumetone failed to alter beta-catenin levels but did decrease beta-catenin nuclear localization and transcriptional activity as gauged by cyclin D1. In conclusion, we demonstrate that the differential mechanisms for beta-catenin suppression may be determined, at least partly, by GSK-3beta.

Liposome-mediated adenomatous polyposis coli gene therapy: a novel anti-adenoma strategy in multiple intestinal neoplasia mouse model

PURPOSE

Familial adenomatous polyposis is a highly penetrant, autosomal dominant disease resulting from a germline mutation of the adenomatous polyposis coli gene. Besides colorectal polyps and cancer, more than 90 percent of familial adenomatous polyposis patients also develop duodenal polyposis with an approximately 5 percent lifetime risk of malignant transformation. Because adenomatous polyposis coli protein has a "gatekeeper role" in the adenoma-carcinoma sequence, replacing its function may reduce polyp formation. We studied the functional outcome of per-oral, liposome-mediated adenomatous polyposis coli gene replacement therapy in a multiple intestinal neoplasia mouse model.

METHODS

Twenty multiple intestinal neoplasia mice, heterozygous for the human homologue adenomatous polyposis coli gene, were randomly assigned to three groups: no treatment (n = 8); control plasmid containing green fluorescence protein reporter gene (n = 6); and plasmid containing the full-length adenomatous polyposis coli gene (n = 6). For the adenomatous polyposis coli-treated and green fluorescence protein reporter gene-treated groups, each mouse received the appropriate plasmid complexed with liposome, administered twice per week by oral gavage regime. Treatment lasted four weeks and all animals were killed at the end of treatment period with harvesting of intestinal tissue for polyp number estimation.

RESULTS

There was a statistically significant 25 percent reduction in the total number of polyps in the adenomatous polyposis coli-treated (73.1 +/- 1.4) group compared with untreated control (97.8 +/- 5.3, P < 0.01, Tukey test) and multiple intestinal neoplasia mice treated with control green fluorescence protein gene (103.3 +/- 1.7, P < 0.01, Tukey test).

CONCLUSION

Adenomatous polyposis coli gene dysfunction underlies tumorigenesis in familial adenomatous polyposis patients and multiple intestinal neoplasia mice. This in vivo study provides evidence to support a novel anti-adenoma strategy using enteral adenomatous polyposis coli gene replacement therapy.

Polyethylene glycol inhibits intestinal neoplasia and induces epithelial apoptosis in Apc(min) mice

Efficacy of a safe and clinically utilized polyethylene glycol formulation (PEG-3350) to suppress intestinal tumors was investigated in the Apc(min) mouse-model of experimental carcinogenesis. Furthermore, based on our previous finding on the induction of apoptosis in HT-29 cells by PEG, we evaluated its ability to stimulate epithelial cell apoptosis in both Apc(min) mouse as well as AOM-treated rat as a potential molecular mechanism of chemoprevention. Twenty-two Apc(min) mice were randomized equally to PEG or vehicle (control) supplementation. Tumors were scored and uninvolved intestinal mucosal apoptosis was assayed using a modified terminal deoxynucleotidyl transferase-mediated nick end-labeling (TUNEL) assay and by immunohistochemical detection of cleaved caspase-3. Supplementation of Apc(min) mice with 10% PEG 3350 (in drinking water) resulted in a 48% (P<0.05) reduction in intestinal tumor burden and induced 2-3 fold increase in mucosal apoptosis. Dietary supplementation of polyethylene glycol (5%) also stimulated colonic mucosal apoptosis 4-5 fold in AOM-treated rats, the regimen that we previously reported to reduce tumor burden by 76% (P<0.05). In summary, we demonstrate, for the first time, that PEG does protect against Apc(min) mouse tumorigenesis. The correlation between pro-apoptotic actions and chemopreventive efficacy of PEG in these models strongly implicates induction of apoptosis as one of the impending mechanisms of chemoprevention.

Alteration of gene expression in normal-appearing colon mucosa of APC(min) mice and human cancer patients

The expression of many genes is altered in colon cancer, but the roles of these genes in carcinogenesis are unclear. Using real-time quantitative PCR, we demonstrated that several genes previously implicated in human colon cancer undergo altered expression in the APC(min) mouse adenomatous polyp, a precursor of cancer, as well as in normal-appearing surrounding mucosa. The five genes that were most highly up-regulated in mouse polyp were also significantly up-regulated in polyp-free colon mucosa. Similar changes occurred in morphologically normal mucosa of surgical sections taken from human cancer patients, frequently extending to the margins. Thus, morphologically normal colon mucosa in APC(min) mice and in human cancer patients is not metabolically normal. Altered gene expression in this tissue does not appear to result from a field effect because there was no correlation between extent of altered regulation and distance from polyp or tumor. Our data suggest that alterations of expression levels of these genes may be an early event in carcinogenesis and a marker of risk for the development of colon cancer.

Effects of adlay on azoxymethane-induced colon carcinogenesis in rats

Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) is a grass crop used in traditional Chinese medicine and as a nutritious food. It has been reported that adlay has anti-inflammatory and anti-tumor activity. Cyclooxygenase-2 (COX-2) is an inducible enzyme functionally related to both inflammation and colon carcinogenesis and is the target of many chemopreventive agents. This study investigated the effect of adlay on colon carcinogenesis and COX-2 expression. In a short-term experiment, male F344 rats were fed diets containing different doses of dehulled adlay and received the colon-specific carcinogen, azoxymethane (AOM), by intraperitoneal injection. All rats were killed after 5 weeks of feeding, and the colons were examined for the preneoplastic lesion, aberrant crypt foci (ACF). Dietary dehulled adlay at levels of 10%, 20%, or 40% significantly reduced the numbers of ACF and aberrant crypts. Dehulled adlay reduced the number of ACF of different sizes but did not affect the crypt multiplicity. Most ACF were found in the middle and distal colons; dehulled adlay significantly suppressed the formation of ACF in the middle colon. In a long-term experiment, male F344 rats were fed diets containing different doses of dehulled adlay and injected with AOM. All rats were killed after 52 weeks of feeding, and colons were examined for tumors and COX-2 protein expression. The results indicated that dehulled adlay did not inhibit colon tumors in spite of a slight suppressing effect in the proximal colon. Rats fed diets containing 20% dehulled adlay had less COX-2 protein expression in both proximal and distal colon tumors. The inconsistent effects between COX-2 protein expression and tumor outcome may be due to regional differences in the colon and the malignancy of the tumors. These findings suggest that dehulled adlay suppresses early events in colon carcinogenesis but not the formation of tumors.

Cyclooxygenase-2 modulates cellular growth and promotes tumorigenesis

Cyclooxygenase (COX)-2 and the prostaglandins resulting from its enzymatic activity have been shown to play a role in modulating cell growth and development of human neoplasia. Evidence includes a direct relationship between COX-2 expression and cancer incidence in humans and animal models, increased tumorigenesis after genetic manipulation of COX-2, and significant anti-tumor properties of non-steroidal anti-inflammatory drugs in animal models and in some human cancers. Recent data showed that COX-2 and the derived prostaglandins are involved in control of cellular growth, apoptosis, and signal through a group of nuclear receptors named peroxisome proliferator-activated receptors (PPARs). In this article we will review some of the findings suggesting that COX-2 is involved in multiple cellular mechanisms that lead to tumorigenesis.

Antiproliferative crude soy saponin extract modulates the expression of IkappaBalpha, protein kinase C, and cyclooxygenase-2 in human colon cancer cells

Frequent consumption of soy and soy-based products is associated with reduced cancer incidence particularly for breast, colon, and prostate cancer. In this study, we examined the effect of crude soy saponin extract on PMA (phorbol 12-myristate 13-acetate)-induced inflammatory responses. Human adenocarcinoma cells (HT-29) were treated with various concentrations of saponin extract for 72 h. Cell growth was measured at 24, 48 and 72 h of incubation, and the PMA-induced expressions of cyclooxygenase-2 (COX-2), protein kinase C (PKC), and IkappaBalpha were determined. The results indicate that crude saponin extract decreased cell growth in a dose- and time-dependent manner. Crude soy saponin extract suppressed the degradation of IkappaBalpha in PMA-stimulated cells, while COX-2 and PKC expressions were significantly down-regulated. These findings support the hypothesis that the soy saponins reduce the risk of colon tumorigenesis possibly by suppressing inflammatory responses.

Are there two sides to colorectal cancer?

Colorectal carcinomas (CRC) that arise proximal (right) or distal (left) to the splenic flexure exhibit differences in incidence according to geographic region, age and gender. Together with observations that tumours in the hereditary cancer syndromes HNPCC and FAP occur predominantly in the right and left colon, respectively, the existence of 2 categories of CRC based on site of origin in the large bowel was proposed more than a decade ago. Differences between normal right and left colonic segments that could favour progression through different tumourigenic pathways are summarized in this review. Accumulating evidence suggests that the risk of CRC conferred by various environmental and genetic factors is different for proximal and distal tumours. Right- and left-sided tumours also exhibit different sensitivities to fluorouracil-based chemotherapy. Such differences are probably related to the molecular characteristics of the tumours, with the microsatellite instability and CpG island methylator phenotypes being associated with right-sided tumours and chromosomal instability with left-sided tumours. Future molecular-based classification systems for CRC that rely upon distinctive gene expression patterns may allow a clearer discrimination of subgroups than that provided by tumour site alone. Until then however, the existence of 2 broadly different groups of cancer defined by site of origin in the colon should be considered in the design of future epidemiologic studies as well as in the design of new clinical trials aimed at testing novel adjuvant therapies.