Chemoprevention of intestinal adenomas in the ApcMin mouse by piroxicam: kinetics, strain effects and resistance to chemosuppression

Crystal Structure and Chemical Bonds in [CuII2(Tolf)4(MeOH)2]∙2MeOH

A new coordination compound of copper(II) with a tolfenamate ligand of the paddle-wheel-like structure [Cu^II₂(Tolf)₄(MeOH)₂]∙2MeOH was obtained and structurally characterized. Chemical bonds of Cu(II)∙∙∙Cu(II) and Cu(II)-O were theoretically analyzed and compared with the results for selected similar structures from the CSD database. QTAIM analysis showed that the Cu(II)∙∙∙Cu(II) interaction has a strength comparable to a hydrogen bond, as indicated by the electron density at a critical point. The remaining QTAIM parameters indicate stability of the Cu(II)∙∙∙Cu(II) interaction. Other methods, such as NCI and NBO, also indicate a significant strength of this interaction. Thus, the Cu(II)∙∙∙Cu(II) interaction can be treated as one of the noncovalent interactions that affects the structure of the coordination compound, the packing of molecules in the crystal, and the general properties of the compound.

Animal Models of Colorectal Cancer: From Spontaneous to Genetically Engineered Models and Their Applications

Colorectal cancer is one of the most common gastrointestinal malignancies in humans, affecting approximately 1.8 million people worldwide. This disease has a major social impact and high treatment costs. Animal models allow us to understand and follow the colon cancer progression; thus, in vivo studies are essential to improve and discover new ways of prevention and treatment. Dietary natural products have been under investigation for better and natural prevention, envisioning to show their potential. This manuscript intends to provide the readers a review of rodent colorectal cancer models available in the literature, highlighting their advantages and disadvantages, as well as their potential in the evaluation of several drugs and natural compounds’ effects on colorectal cancer.

Sulindac plus a phospholipid is effective for polyp reduction and safer than sulindac alone in a mouse model of colorectal cancer development

Background

Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and sulindac are effective for colorectal cancer prevention in humans and some animal models, but concerns over gastro-intestinal (GI) ulceration and bleeding limit their potential for chemopreventive use in broader populations. Recently, the combination of aspirin with a phospholipid, packaged as PL-ASA, was shown to reduce GI toxicity in a small clinical trial. However, these studies were done for relatively short periods of time. Since prolonged, regular use is needed for chemopreventive benefit, it is important to know whether GI safety is maintained over longer use periods and whether cancer prevention efficacy is preserved when an NSAID is combined with a phospholipid.

Methods

As a first step to answering these questions, we treated seven to eight-week-old, male and female C57B/6 Apc^min/+ mice with the NSAID sulindac, with and without phosphatidylcholine (PC) for 3-weeks. At the end of the treatment period, we evaluated polyp burden, gastric toxicity, urinary prostaglandins (as a marker of sulindac target engagement), and blood chemistries.

Results

Both sulindac and sulindac-PC treatments resulted in significantly reduced polyp burden, and decreased urinary prostaglandins, but sulindac-PC treatment also resulted in the reduction of gastric lesions compared to sulindac alone.

Conclusions

Together these data provide pre-clinical support for combining NSAIDs with a phospholipid, such as phosphatidylcholine to reduce GI toxicity while maintaining chemopreventive efficacy.

The Na-O bond in sodium fenamate

The one-dimensional polymeric structure of sodium diaquafenamate-water (1/1) was studied by X-ray diffraction. The sodium cation is coordinated to one oxygen atom of the carboxylate group and to four water oxygen atoms. To characterize the Na-O bonds, the quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) approaches have been used. Both methods confirmed that the Na-O bonds are very weak, comparable with the weak N-H...O intramolecular hydrogen bond. The polymeric structure is stabilized by the interaction of the sodium cation with the surrounding water molecules.

DFT and molecular docking investigations of oxicam derivatives

The organic molecule tenoxicam and similar derivatives, piroxicam and isoxicam have been studied by quantum chemical theory (DFT), FT-Raman and FT-IR. By FMOs energies the charge transfer inside the molecules are obtained. The UV-Vis spectra of the compounds are simulated to study the electronic transition in the target molecules. By using natural bond orbital (NBO), charge delocalization analyzes arising from hyper conjugative interactions and the stability of the molecules are obtained. First order hyperpolarizability of piroxicam is higher than that of isoxicam and tenoxicam. The reactive areas are thoroughly studied by MEP. Prediction of Activity Spectra gives activities, anti-inflammatory, CYP2C9 substrate and gout treatment. Docked ligands form a stable complex with the receptors.

Effect of EI24 expression on the tumorigenesis of ApcMin/+ colorectal cancer mouse model

Etoposide-induced 2.4 kb transcript (EI24, also known as PIG8) is a p53 target gene involved in cell growth suppression and apoptosis and known to be frequently altered in human cancers. Although EI24 expression is decreased in various cancers and is associated with colorectal cancer progression and metastasis, the physiological function of EI24 in colorectal cancer is yet unclear. We generated an Ei24 conditional transgenic (Tg) mouse to study the therapeutic effects of Ei24 in vivo and evaluated whether Ei24 plays a role of a tumor suppressor using Ei24 Tg mouse crossed with Apc^Min/+ mouse, which develops multiple intestinal adenomas. The overexpression of Ei24 failed to cause any notable difference in the number of polyps, lengths of the intestine and spleen, and survival rate between Apc^Min/+ and Apc^Min/+Ei24 Tg mice. Ei24 plays no significant role in colon cancer caused by the substitutional mutation of Apc in mice. Therefore, our result dismisses the hypothesized direct link between Apc^Min/+ mutation and Ei24 expression in colorectal cancer model.

Dclk1, a tumor stem cell marker, regulates pro-survival signaling and self-renewal of intestinal tumor cells

BACKGROUND

More than 80% of intestinal neoplasia is associated with the adenomatous polyposis coli (APC) mutation. Doublecortin-like kinase 1 (Dclk1), a kinase protein, is overexpressed in colorectal cancer and specifically marks tumor stem cells (TSCs) that self-renew and increased the tumor progeny in Apc ^Min/+ mice. However, the role of Dclk1 expression and its contribution to regulating pro-survival signaling for tumor progression in Apc mutant cancer is poorly understood.

METHODS

We analyzed DCLK1 and pro-survival signaling gene expression datasets of 329 specimens from TCGA Colon Adenocarcinoma Cancer Data. The network of DCLK1 and pro-survival signaling was analyzed utilizing the GeneMANIA database. We examined the expression levels of Dclk1 and other stem cell-associated markers, pro-survival signaling pathways, cell self-renewal in the isolated intestinal epithelial cells of Apc ^Min/+ mice with high-grade dysplasia and adenocarcinoma. To determine the functional role of Dclk1 for tumor progression, we knocked down Dclk1 and determined the pro-survival signaling pathways and stemness. We used siRNA technology to gene silence pro-survival signaling in colon cancer cells in vitro. We utilized FACS, IHC, western blot, RT-PCR, and clonogenic (self-renewal) assays.

RESULTS

We found a correlation between DCLK1 and pro-survival signaling expression. The expression of Dclk1 and stem cell-associated markers Lgr5, Bmi1, and Musashi1 were significantly higher in the intestinal epithelial cells of Apc ^Min/+ mice than in wild-type controls. Intestinal epithelial cells of Apc ^Min/+ mice showed increased expression of pro-survival signaling, pluripotency and self-renewal ability. Furthermore, the enteroids formed from the intestinal Dclk1⁺ cells of Apc ^Min/+ mice display higher pluripotency and pro-survival signaling. Dclk1 knockdown in Apc ^Min/+ mice attenuates intestinal adenomas and adenocarcinoma, and decreases pro-survival signaling and self-renewal. Knocking down RELA and NOTCH1 pro-survival signaling and DCLK1 in HT29 and DLD1 colon cancer cells in vitro reduced the tumor cells' ability to self-renew and survive.

CONCLUSION

Our results indicate that Dclk1 is essential in advancing intestinal tumorigenesis. Knocking down Dclk1 decreases tumor stemness and progression and is thus predicted to regulate pro-survival signaling and tumor cell pluripotency. This study provides a strong rationale to target Dclk1 as a treatment strategy for colorectal cancer.

Micellar dipolar rearrangement is sensitive to hydrophobic chain length: Implication for structural switchover of piroxicam

The interfacial properties of the membrane are exceptionally vital in drug-membrane interaction. They not only select out a particular prototropic form of the drug molecule for incorporation, but are also potent enough to induce structural switchover of these drugs in several cases. In this work, we quantitatively monitored the change in dipolar rearrangement of the micellar interface (as a simplified membrane mimic) by measuring the dielectric constant and dipole potential with the micellization of SDS at pH 3.6. The dielectric constant and dipole potential were measured utilizing the fluorescence of polarity sensitive probe, pyrene and potential-sensitive probe, di-8-ANEPPS, respectively. Our study demonstrates that the change in dipolar rearrangement directly influences the switchover equilibrium between the anionic and neutral from of piroxicam. We have further extended our work to evaluate the effect of hydrophobic chain length of the surfactants on the dipolar rearrangement and its effect on the structural switchover of piroxicam. It is interesting that the extent of switchover of piroxicam is directly correlated with the dipolar rearrangement induced bythe varying hydrophobic chain length of the surfactants. To the best of our knowledge, our results constitute the first report to show the dependence of dipole potential on the hydrophobic chain length of the surfactant and demonstrate that the dipolar rearrangement directly tunes the extent of structural switchover of piroxicam, which was so far only intuitive. We consider that this new finding would have promising implication in drug distribution and drug efficacy.

Lentivirus-mediated somatic recombination and development of a novel mouse model for sporadic colorectal cancer

In this study, we have developed a novel mouse model for sporadic colorectal cancer (CRC) by utilizing APC conditional knockout (Apc(CKO) ) mouse and lentivirus encoding Cre recombinase and a reporter gene (EGFP or LacZ). Lentiviral transduction of colonic crypt stem cells allowed for the long-term expression of reporter gene as well as excision of floxed Apc alleles, which resulted in tumor development. Tumors represented adenoma stages along with the nuclear accumulation of β-catenin. Loss of E-cadherin at the cellular junctions and strong expression of Vimentin suggested the sign of active epithelial-mesenchymal transition. Moreover, nuclear staining of Ki67 inside epithelial cells of aberrant crypts demonstrated their higher proliferative nature. Erratic downstream signaling of activated Wnt/β-catenin, AKT/mTOR, and Notch pathways provided strong evidence towards the higher proliferative index of epithelial cells inside the aberrant crypts. These results do recapitulate the findings of previous APC mutant mouse models. Our model represents sporadic CRC more precisely as (i) tumors result from somatic mutations but not from germline; (ii) tumors develop in colon not in small intestine; (iii) few tumors develop at the distal end of colons. Additionally, our model allows for the long-term expression of the gene(s), which get integrated into the host cell genome and provides an ability to track the tumor growth. © 2016 Wiley Periodicals, Inc.

DCLK1 facilitates intestinal tumor growth via enhancing pluripotency and epithelial mesenchymal transition

Doublecortin-like kinase 1 (Dclk1) is overexpressed in many cancers including colorectal cancer (CRC) and it specifically marks intestinal tumor stem cells. However, the role of Dclk1 in intestinal tumorigenesis in Apc mutant conditions is still poorly understood. We demonstrate that Dclk1 expression and Dclk1+ cells are significantly increased in the intestinal epithelium of elderly Apc^Min/+ mice compared to young Apc^Min/+ mice and wild type mice. Intestinal epithelial cells of Apc^Min/+ mice demonstrate increased pluripotency, self-renewing ability, and EMT. Furthermore, miRNAs are dysregulated, expression of onco-miRNAs are significantly increased with decreased tumor suppressor miRNAs. In support of these findings, knockdown of Dclk1 in elderly Apc^Min/+ mice attenuates intestinal adenomas and adenocarcinoma by decreasing pluripotency, EMT and onco-miRNAs indicating that Dclk1 overexpression facilitates intestinal tumorigenesis. Knocking down Dclk1 weakens Dclk1-dependent intestinal processes for tumorigenesis. This study demonstrates that Dclk1 is critically involved in facilitating intestinal tumorigenesis by enhancing pluripotency and EMT factors in Apc mutant intestinal tumors and it also provides a potential therapeutic target for the treatment of colorectal cancer.

Disruption of Escherichia coli Nissle 1917 K5 capsule biosynthesis, through loss of distinct kfi genes, modulates interaction with intestinal epithelial cells and impact on cell health

Escherichia coli Nissle 1917 (EcN) is among the best characterised probiotics, with a proven clinical impact in a range of conditions. Despite this, the mechanisms underlying these "probiotic effects" are not clearly defined. Here we applied random transposon mutagenesis to identify genes relevant to the interaction of EcN with intestinal epithelial cells. This demonstrated mutants disrupted in the kfiB gene, of the K5 capsule biosynthesis cluster, to be significantly enhanced in attachment to Caco-2 cells. However, this phenotype was distinct from that previously reported for EcN K5 deficient mutants (kfiC null mutants), prompting us to explore further the role of kfiB in EcN:Caco-2 interaction. Isogenic mutants with deletions in kfiB (EcNΔkfiB), or the more extensively characterised K5 capsule biosynthesis gene kfiC (EcNΔkfiC), were both shown to be capsule deficient, but displayed divergent phenotypes with regard to impact on Caco-2 cells. Compared with EcNΔkfiC and the EcN wild-type, EcNΔkfiB exhibited significantly greater attachment to Caco-2 cells, as well as apoptotic and cytotoxic effects. In contrast, EcNΔkfiC was comparable to the wild-type in these assays, but was shown to induce significantly greater COX-2 expression in Caco-2 cells. Distinct differences were also apparent in the pervading cell morphology and cellular aggregation between mutants. Overall, these observations reinforce the importance of the EcN K5 capsule in host-EcN interactions, but demonstrate that loss of distinct genes in the K5 pathway can modulate the impact of EcN on epithelial cell health.

Vibrational spectra (FT-IR, FT-Raman), frontier molecular orbital, first hyperpolarizability, NBO analysis and thermodynamics properties of Piroxicam by HF and DFT methods

The solid phase FT-IR and FT-Raman spectra of 4-Hydroxy-2-methyl-N-(2-pyridinyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (Piroxicam) have been recorded in the region 4000-400 and 4000-100cm(-1) respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of piroxicam in the ground state have been calculated by Hartree-Fock (HF) and density functional theory (DFT) methods using 6-311++G(d,p) basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimental obtained by FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the title compound has been made on the basis of the calculated potential energy distribution (PED). The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) are also performed. The linear polarizability (α) and the first order hyper polarizability (β) values of the title compound have been computed. The molecular stability arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

Oxicams, a class of nonsteroidal anti-inflammatory drugs and beyond

Oxicams are a class of nonsteroidal anti-inflammatory drugs (NSAIDs) structurally related to the enolic acid class of 4-hydroxy-1,2-benzothiazine carboxamides. They are used clinically to treat both acute and chronic inflammation by inhibiting the activity of the two cyclooxygenase (COX) isoforms, COX-1 and COX-2. Oxicams are structurally distinct from all other NSAIDs, exhibiting a novel binding pose in the COX active site. The 4-hydroxyl group on the thiazine ring partners with Ser-530 via hydrogen bonding while two coordinated water molecules mediate a polar interaction between the oxicam and COX. The rotation of Leu-531 in the complex opens a new pocket, which is not used for binding other NSAIDs to the enzyme. This structure provides the basis for understanding documented structure-activity relationships within the oxicam class. In addition, from the oxicam template, a series of potent microsomal prostaglandin E synthase-1 (mPGES-1) inhibitors represents a new direction for drug development. Here, we review the major route of oxicam synthesis and structure-activity for COX inhibition, as well as recent advances in oxicam-mediated mPGES-1 inhibition.

Lung inflammatory response syndrome after cardiac-operations and treatment of lornoxicam

The majority of patients survive after extracorporeal circulation without any clinically apparent deleterious effects. However, disturbances exist in various degrees sometimes, which indicate the harmful effects of cardiopulmonary bypass (CPB) in the body. Several factors during extracorporeal circulation either mechanical dependent (exposure of blood to non-biological area) or mechanical independent (surgical wounds, ischemia and reperfusion, alteration in body temperature, release of endotoxins) have been shown to trigger the inflammatory reaction of the body. The complement activation, the release of cytokines, the leukocyte activation and accumulation as well as the production of several "mediators" such as oxygen free radicals, metabolites of arachidonic acid, platelet activating factors (PAF), nitric acid, and endothelin. The investigation continues today on the three metabolites of lornoxicam (the hydroxylated metabolite and two other metabolites of unknown chemical composition) to search for potential new pharmacological properties and activities.

Polyphenolic Phytochemicals Versus Non-Steroidal Anti-Inflammatory Drugs: Which Are Better Cancer Chemopreventive Agents?

Non steroidal antiinflammatory drugs (NSAIDs) delay the onset of cancer in rodent models of colorectal carcinogenesis. Clinical trials suggest that they can interfere with preneoplasia in humans; thus they may be chemopreventive agents in humans. As NSAIDs posses unwanted side effects, efforts are being invested in the identification of alternative agents with comparable chemopreventive efficacy but without the toxicity of NSAIDs. Polyphenolic phytochemicals such as curcumin and resveratrol are promising candidates. Like NSAIDs they suppress carcinogenesis in the ApcMin+ mouse model. Clinical pilot studies of curcumin show that it is safe at doses of up to 3.6g daily, and that the levels of curcumin which can be achieved in the gastrointestinal tract exert pharmacological activity. More clinical evaluation will help establish whether polyphenolic phytochemicals are indeed safe and efficacious alternatives to NSAIDs.

Thymoquinone attenuates tumor growth in ApcMin mice by interference with Wnt-signaling

Background

Patients with familial adenomatous polyposis (FAP) are at increased risk for the development of colorectal cancer. Surgery and chemoprevention are the most effective means to prevent cancer development. Thymoquinone (TQ) is considered the main compound of the volatile Nigella sativa seed oil and has been reported to possess anticarcinogenic properties. In this study we evaluated the chemopreventive properties of TQ in a mouse model of FAP.

Methods

APC^Min mice were fed with chow containing 37.5 mg/kg or 375 mg/kg TQ for 12 weeks. H&E stained intestine tissue sections were assessed for tumor number, localization, size, and grade. Immunohistochemistry for β-catenin, c-myc, Ki-67 and TUNEL-staining was performed to investigate TQ’s effect on major colorectal cancer pathways. TQ’s impact on GSK-3β and β-catenin were studied in RKO cells.

Results

375 mg/kg but not 37.5 mg/kg TQ decreased the number of large polyps in the small intestine of APC^Min mice. TQ induced apoptosis in the neoplastic tissue but not in the normal mucosa. Furthermore, upon TQ treatment, β-catenin was retained at the membrane and c-myc decreased in the nucleus, which was associated with a reduced cell proliferation in the villi. In vitro, TQ activated GSK-3β, which induced membranous localization of β-catenin and reduced nuclear c-myc expression.

Conclusions

In summary, TQ interferes with polyp progression in Apc^Min mice through induction of tumor-cell specific apoptosis and by modulating Wnt signaling through activation of GSK-3β. Nigella sativa oil (or TQ) might be useful as nutritional supplement to complement surgery and chemoprevention in FAP.

Cancer in inflammatory bowel disease: lessons from animal models

PURPOSE OF REVIEW

Human colitis-associated cancers (CAC) represent a heterogeneous group of conditions in which multiple oncogenic pathways are involved. In this article, we review the latest studies using genetic, chemical, bacterial and innate immune-mediated experimental models of CAC.

RECENT FINDINGS

Using the azoxymethane-dextran sodium sulfate model, wound healing pathways seem to be required in the development of CAC. There is also an emerging understanding that commensal and/or pathogenic bacteria can promote tumorigenesis, through T cell and TLR-mediated inflammation. Using specific transgenic mice (villin-CD98, T cell SMAD7, villin-TLR4) or specific knockout mice, investigators have determined that derangements in epithelial or innate and adaptive immune pathways can result in CAC. Subtle perturbations in epithelial repair - both too little or too exuberant - can render mice susceptible to tumorigenesis.

SUMMARY

With the aid of animal models, we have witnessed a rapid expansion of our knowledge of the molecular and immunologic mechanisms underlying inflammatory cancers. Though animal models have contributed a discrete amount of information to our understanding of tumorigenesis in the setting of intestinal inflammation, it is clear that no single animal model will be able to adequately recapitulate the pathogenesis of complex colorectal cancers, but each model gets us one step closer to comprehending the nature of CAC.

Binding of Cu(II) complexes of oxicam NSAIDs to alternating AT and homopolymeric AT sequences: differential response to variation in backbone structure

Besides their principal functions as painkillers and anti-inflammatory agents, drugs belonging to the nonsteroidal anti-inflammatory drug (NSAID) group also have anticancer properties. Cu(II) complexes of these drugs enhance the anticancer effect. How they exert this effect is not clear. As a possible molecular mechanism, our group has already shown that the Cu(II) complexes of two oxicam NSAIDs with anticancer properties, viz. piroxicam and meloxicam, can directly bind to the DNA backbone. AT stretches are abundant in the eukaryotic genome. These stretches are more accessible to binding of different ligands, resulting in expression of different functions. AT stretches containing both alternating base pairs and homopolymeric bases in individual strands show subtle differences in backbone structures. It is therefore of interest to see how the Cu(II)-NSAID complexes respond to such differences in backbone structure. Binding studies of these complexes with alternating polydA-dT and homopolymeric polydA-polydT have been conducted using UV-vis absorption titration studies, UV melting studies and circular dichroism spectroscopy. Competitive binding with the standard intercalator ethidium bromide and the minor groove binder 4',6-diamidino-2-phenylindole was monitored using fluorescence to identify the possible binding mode. Our results show that Cu(II)-NSAID complexes are highly sensitive to the subtle differences in backbone structures of polydA-dT and polydA-polydT and respond to them by exhibiting different binding properties, such as binding constants, effect on duplex stability and binding modes. Both complexes have a similar binding mode with polydA-dT, which is intercalative, but for polydA-polydT, the results point to a mixed mode of binding.

The role of thrombospondin 1 on intestinal inflammation and carcinogenesis

Crohn’s disease and ulcerative colitis are inflammatory bowel diseases (IBD) quite common in the United States and other Western countries. Patients suffering IBD are at greater risk of developing colorectal adenocarcinoma than the general population. Both, the adenomacarcinoma and the inflammation-carcinogenesis processes are characterized by active angiogenesis. Recent studies also have shown that anti-angiogenesis might be a novel therapeutic approach for IBD. Thrombospondin 1 (TSP1) is an extracellular protein well known for its anti-angiogenic properties. TSP1 also has key functions in inflammation, which is assumed to be the primary cause for carcinogenesis in IBD. This review is focused on the role of TSP1 in colorectal carcinogenesis. The therapeutic effects of TSP derived-peptides on inhibiting the inflammation-carcinogenesis progression are also discussed.

Membrane fusion induced by small molecules and ions

Membrane fusion is a key event in many biological processes. These processes are controlled by various fusogenic agents of which proteins and peptides from the principal group. The fusion process is characterized by three major steps, namely, inter membrane contact, lipid mixing forming the intermediate step, pore opening and finally mixing of inner contents of the cells/vesicles. These steps are governed by energy barriers, which need to be overcome to complete fusion. Structural reorganization of big molecules like proteins/peptides, supplies the required driving force to overcome the energy barrier of the different intermediate steps. Small molecules/ions do not share this advantage. Hence fusion induced by small molecules/ions is expected to be different from that induced by proteins/peptides. Although several reviews exist on membrane fusion, no recent review is devoted solely to small moleculs/ions induced membrane fusion. Here we intend to present, how a variety of small molecules/ions act as independent fusogens. The detailed mechanism of some are well understood but for many it is still an unanswered question. Clearer understanding of how a particular small molecule can control fusion will open up a vista to use these moleucles instead of proteins/peptides to induce fusion both in vivo and in vitro fusion processes.

Animal models of colitis-associated carcinogenesis

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

Mechanisms of intestinal inflammation and development of associated cancers: lessons learned from mouse models

Chronic inflammation is strongly associated with approximately 1/5th of all human cancers. Arising from combinations of factors such as environmental exposures, diet, inherited gene polymorphisms, infections, or from dysfunctions of the immune response, chronic inflammation begins as an attempt of the body to remove injurious stimuli; however, over time, this results in continuous tissue destruction and promotion and maintenance of carcinogenesis. Here we focus on intestinal inflammation and its associated cancers, a group of diseases on the rise and affecting millions of people worldwide. Intestinal inflammation can be widely grouped into inflammatory bowel diseases (ulcerative colitis and Crohn's disease) and celiac disease. Long-standing intestinal inflammation is associated with colorectal cancer and small-bowel adenocarcinoma, as well as extraintestinal manifestations, including lymphomas and autoimmune diseases. This article highlights potential mechanisms of pathogenesis in inflammatory bowel diseases and celiac disease, as well as those involved in the progression to associated cancers, most of which have been identified from studies utilizing mouse models of intestinal inflammation. Mouse models of intestinal inflammation can be widely grouped into chemically induced models; genetic models, which make up the bulk of the studied models; adoptive transfer models; and spontaneous models. Studies in these models have lead to the understanding that persistent antigen exposure in the intestinal lumen, in combination with loss of epithelial barrier function, and dysfunction and dysregulation of the innate and adaptive immune responses lead to chronic intestinal inflammation. Transcriptional changes in this environment leading to cell survival, hyperplasia, promotion of angiogenesis, persistent DNA damage, or insufficient repair of DNA damage due to an excess of proinflammatory mediators are then thought to lead to sustained malignant transformation. With regards to extraintestinal manifestations such as lymphoma, however, more suitable models are required to further investigate the complex and heterogeneous mechanisms that may be at play.

Longitudinal assessment of colonic tumor fate in mice by computed tomography and optical colonoscopy

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate the relative merits of micro-computed tomograph colonography (mCTC) and optical colonoscopy (OC) for longitudinal studies of colonic tumors in mice.

MATERIALS AND METHODS

Colonic tumors in mice carrying the Min allele of Apc were followed over several weeks using mCTC and OC. A total of 146 colonic tumors were monitored: 62 in 32 untreated Min mice, 53 in 43 Min mice treated with 5-fluorouracil (5-FU), and 31 in 17 Min mice treated with piroxicam.

RESULTS

Colonic tumors in Min mice had three different spontaneous fates: 29 grew, 24 remained static, and 9 regressed. Treating Min mice with 5-FU increased the percentage of regressing tumors from 15% to 58%. The response was dependent in part on the initial size of the tumor. By contrast, treating Min mice with piroxicam did not alter colonic tumor fate.

CONCLUSIONS

mCTC and OC can be used to determine the spontaneous fates of colonic tumors in mice and to document their individual responses to treatment. The ability to follow individually annotated colonic tumors reduces the number of mice needed for testing.

APC10.1 cells as a model for assessing the efficacy of potential chemopreventive agents in the Apc(Min) mouse model in vivo

Apc(Min) mice are widely used for mechanism and efficacy studies associated with the development of chemopreventive agents. APC10.1 cells have been derived from Apc(Min) mouse adenomas and retain the heterozygous Apc genotype. We tested the hypothesis that this cell type may provide an in vitro model to predict chemopreventive activity of agents in the Apc(Min) mouse in vivo. The growth inhibitory properties of 14 putative colorectal cancer chemopreventive agents, tricin, apigenin, 3',4',5',5,7-pentamethoxyflavone, resveratrol, curcumin, 3,4-methylenedioxy-3',4',5'-trimethoxychalcone (DMU135), 3,4,5,4'-tetramethoxystilbene (DMU212), celecoxib, aspirin, piroxicam, all-trans-retinoic acid, difluoromethylornithine (DFMO), quercetin and cyanidin-3-glucoside, were studied in this cell line, and the IC(50) values were calculated. The IC(50) values were plotted against previously published data of reduction of adenoma numbers caused by these agents in Apc(Min) mice. The correlation co-efficient was 0.678 (p<0.01), suggesting that there was a tentative correlation between the ability to inhibit the growth of APC10.1 cells and the ability to delay adenoma development in vivo. If this relationship is supported by using further agents, APC10.1 cells may serve in the future as an initial screen to prioritise compounds for assessing chemopreventive efficacy in Apc(Min) mice in vivo. Such a screen could reduce the number of animals required to find active agents, help reduce costs and increase throughput.

CHEMOPREVENTION: MOUSE COLON AND LUNG TUMOR BIOASSAY AND MODULATION OF DNA METHYLATION AS A BIOMARKER

Lung and colon tumors were induced in A/J, C3H, and A/J X C3H (AC3) mice by administering 16 mg/kg vinyl carbamate followed by 6 weekly doses of 12 mg/kg azoxymethane (AOM). Beginning 1 week after carcinogen treatment, the mice received chemopreventive agents, dexamethasone or piroxicam, at 0.1 and 75 mg/kg in the diet, respectively. Both AOM and vinyl carbamate induces lung tumors, but only AOM induced colon tumors. The strain sensitivity for both colon and lung tumors was A/J > AC3 > C3H mice. Dexamethasone and piroxicam reduced the multiplicity of colon and lung tumors in A/J and AC3 mice, demonstrating the advantage of a combined colon and lung bioassay. The ability of budesonide, a drug that prevents mouse lung tumors, to modulate DNA methylation in vinyl carbamate-induced lung tumors was also determined. Budesonide administered for only 7 days prior to sacrifice caused a dose-dependent (0.6 to 2.4 mg/kg diet) reversal in tumors of DNA hypomethylation and hypomethylation of the insulin-like growth factor (IGF)-II gene in the differentially methylated region (DMR) 2 region of exons 4 to 5. Longer treatment with budesonide reversed hypomethylation when administered up to the time of sacrifice. These results indicate that reversal of the hypomethylation of DNA and of specific genes in lung tumors may be applicable as a surrogate end-point biomarker for chemoprevention.

Effects of dietary flaxseed on intestinal tumorigenesis in Apc(Min) mouse

Dietary flaxseed has been shown to prevent azoxymethane (AOM)-induced colorectal cancers in male Fisher rats. The present study was designed to investigate the chemopreventive effects of dietary flaxseed on the development of intestinal tumors in Apc(Min) mice. Apc(Min) mice were divided into five different groups, fed with control (AIN-93M meal), corn meal, flaxseed meal, corn oil, and flaxseed oil supplemented diets. Results showed that dietary flaxseed significantly decreased (P < 0.05) tumor multiplicity and size in the small intestine and colon as compared to control, corn-treated groups. Intestine, colon, and serum samples of corn-treated groups showed higher levels of omega -6 fatty acids, whereas the flaxseed treated groups exhibited higher levels of omega -3 fatty acids. Lignans were detected in the serum, intestine, and colon samples for flaxseed meal group. COX-1 and COX-2 expression in the colon samples from the flaxseed meal group were significantly lower (P < 0.05) as compared to the corn meal group. Dietary flaxseed may be chemopreventive for intestinal tumor development in Apc(Min) mice possibly by increasing omega -3 fatty acid levels, lignans, and decreasing COX-1 and COX-2 levels.

Intestinal tumour chemoprevention with the antioxidant lipoic acid stimulates the growth of breast cancer

OBJECTIVE

Breast and intestinal cancers chemoprevention would significantly impact on cancer care. Hence, we assessed the chemopreventive efficacy of the antioxidant lipoic acid (LA) in mice overexpressing a wild-type Her2/neu, as an animal model of breast cancer, and in APCmin mice for intestinal cancer.

METHODS

Mice were randomised at weaning, and were treated with LA for lifetime. Tumour incidence, growth rate and histopathology were analysed on an individual tumour basis.

RESULTS

LA efficiently chemoprevented tumour appearance in APCmin mice. Strikingly, though, LA doses, that were chemopreventive in APCmin mice (> or = 300 microg/day), increased breast cancer growth in Her2/neu mice. Even in experimental groups, where LA overall reduced tumour risk (80 microg/day), LA consistently stimulated the growth rate of established breast tumours. Breast and colon tumours incidence was unaffected by LA, indicating no significant impact of LA on tumour initiation and no protection from mutations driving tumour progression.

CONCLUSIONS

Stimulation of breast cancer growth and inhibition of intestinal tumours by LA indicate that diverse growth control mechanisms are modulated by LA in different organs. Concern is raised about the use of LA for cancer chemoprevention.

Sulindac treatment alters collagen and matrilysin expression in adenomas of ApcMin/+ mice

Non-steroidal anti-inflammatory drugs (NSAIDs) have shown potential as chemopreventive agents against cancer formation, especially colorectal cancers. However, the mechanisms by which these drugs act are not fully understood. In this study, Apc(Min/+) mice, a genetic model of human familial adenomatous polyposis, were treated with sulindac, and these mice demonstrated tumor reduction of >80%, consistent with previous reports. Gene microarray analyses of RNA from adenoma-derived dysplastic epithelial cells revealed that collagen genes, viz. Col1a2, Col5a2, Col6a2 and Col6a3, were upregulated, and matrilysin matrix metalloproteases-7 (Mmp7) was downregulated, in sulindac-treated mice. Reverse transcription-polymerase chain reaction validated gene expression of the Col6a2 subunit of collagen VI and of Mmp7. Confocal microscopy and immunofluorescence showed that within the tumors of non-treated mice, collagen VI was present in low amounts, but was enhanced within the tumors of sulindac-treated mice. Collagens I and V demonstrated similar patterns, but were not as prominent as collagen VI. Mmp7 was found in 'hot spot' areas within the tumors of Apc(Min/+) mice treated with the vehicle, but was greatly diminished in those mice treated with sulindac. Studies with Apc(Min/+)/Mmp7(-/-) double-deficient mice demonstrated the reciprocal relationships of Mmp7 expression and the levels of these three collagens in vivo. The results of this study demonstrated that sulindac was effective in increasing the expression of different collagens and decreasing the expression of Mmp7, effects that may contribute to altered tumor burden in cancer patients undergoing NSAIDs treatments.

Rodent endosonography to monitor esophageal cancer

Animal models of luminal cancers are important to understand and assess chemopreventive and chemotherapeutic interventions. However, the ability to assess tumor growth and response without animal sacrifice is limited. We assessed the ability of luminal sonography to assess the presence of tumor and its size in a surgical esophagojejunostomy model of esophageal cancer. Luminal sonography had a sensitivity of 88%, specificity of 100%, and accuracy of 93% in identifying the esophageal cancers. The tumor dimensions on luminal sonography were within 11% of autopsy measurements. Minimal tumor dimension was 2 mm and maximum 6.2 mm. The procedure was feasible without technical difficulty. In conclusion, rodent endosonography is a useful technique that can accurately determine the presence of tumors as well as their dimensions.

Inhibition of VEGF-A prevents the angiogenic switch and results in increased survival of Apc+/min mice

Anti-VEGF-A monoclonal antibodies, in combination with chemotherapy, result in a survival benefit in patients with metastatic colorectal and non-small cell lung cancer, but little is known regarding the impact of anti-VEGF-A therapy on benign or premalignant tumors. The Apc+/min mice have been widely used as a model recapitulating early intestinal adenoma formation. To investigate whether tumor growth in Apc+/min mice is mediated by VEGF-A-dependent angiogenesis, we used two independent approaches to inhibit VEGF-A: monotherapy with a monoclonal antibody (Mab) targeting VEGF-A and genetic deletion of VEGF-A selectively in intestinal epithelial cells. Short-term (3 or 6 weeks) treatment with anti-VEGF-A Mab G6-31 resulted in a nearly complete suppression of adenoma growth throughout the small intestine. Growth inhibition by Mab G6-31 was associated with a decrease in vascular density. Long-term (up to 52 weeks) treatment with Mab G6-31 led to a substantial increase in median survival. Deletion of VEGF-A in intestinal epithelial cells of Apc+/min mice yielded a significant inhibition of tumor growth, albeit of lesser magnitude than that resulting from Mab G6-31 administration. These results establish that inhibition of VEGF-A signaling is sufficient for tumor growth cessation and confers a long-term survival benefit in an intestinal adenoma model. Therefore, VEGF-A inhibition may be a previously uncharacterized strategy for the prevention of the angiogenic switch and growth in intestinal adenomas.

Interaction of piroxicam with mitochondrial membrane and cytochrome c

Modulation of surface properties of biomembranes by any ligand leading to permeabilization, fusion, rupture, etc. is a fundamental requirement for many biological processes. In this work, we present the interaction of piroxicam, a long acting Non-Steroidal Anti-Inflammatory Drug (NSAID) with isolated mitochondria, membrane mimetic systems, intact cells and a mitochondrial protein cytochrome c. Dye permeabilization study on isolated mitochondria indicates that piroxicam can permeabilize mitochondrial membrane. Direct imaging by Scanning Electron Microscope (SEM) shows that piroxicam induces changes in mitochondrial membrane morphology leading to fusion and rupture. Transmission Electron Microscope (TEM) imaging of piroxicam treated DMPC vesicles and mixed micelles formed from CTAB and SDS show that causing membrane fusion is a general property of piroxicam at physiological pH. In intact cells viz., V79 Chinese Hamster lung fibroblast, piroxicam is capable of releasing cytochrome c from mitochondria into the cytosol in a dose dependent manner along with the enhancement of downstream proapoptotic event viz., increase in caspase-3 activity. We have also shown that piroxicam can reduce cytochrome c within a time frame relevant to its lifetime in blood plasma. UV-visible spectroscopy has been used to study the reaction mechanism and kinetics in detail, allowing us to propose and validate a Michaelis-Menten like reaction scheme. CD spectroscopy shows that small but significant changes occur in the structure of cytochrome c when reduced by piroxicam.

Electrochemical monitoring of piroxicam in different pharmaceutical forms with multi-walled carbon nanotubes paste electrode

The electrochemical behavior of piroxicam on a multi-walled carbon nanotubes electrode for the first time was investigated. A highly sensitive and fast responding sensor for determination of piroxicam was simply and conveniently fabricated. The constructed electrode exhibits efficiently catalytic activity for the electrooxidation of piroxicam at a reduced over potential with high sensitivity, stability, and long lifetime in the wide concentration rang of piroxicam. The oxidation process was found to be dependent on the pH of the supporting electrolyte. The behavior is further exploited as a sensitive detection method for piroxicam determination by differential pulse voltammetry. Under the optimized conditions the calibration plots are linear in the concentration range of 0.15-5 microg ml(-1). Application of the method for the determination of the drug in the dosage form (Feledene capsules and tablets and also piroxicam gel), without any interference, from the excipients, resulted in acceptable deviation from the stated concentrations. Recoveries were obtained in the range 96.35-104.16%. The detection limit of 0.1 microg ml(-1) was obtained for piroxicam determination.

Development of gastric tumors in Apc(Min/+) mice by the activation of the beta-catenin/Tcf signaling pathway

Although several lines of evidence suggest the involvement of the Wnt pathway in the development of gastric cancers, the functional significance of the pathway in gastric carcinogenesis is still poorly defined. To examine the role of the Apc/beta-catenin signaling pathway in the development of gastric cancers, we investigated the gastric mucosa of the Apc(Min/+) mouse, which is a murine model for familial adenomatous polyposis, carrying a germ-line mutation at codon 850 of Apc. We found that aged Apc(Min/+) mice spontaneously develop multiple tumors in the stomach, which are accompanied by loss of heterozygosity of Apc. Such tumors consisted of adenomatous glands with strong nuclear accumulation of beta-catenin. Even a single adenomatous gland already showed nuclear accumulation of beta-catenin, suggesting that Apc/beta-catenin pathway is an initiating event in gastric tumorigenesis in Apc(Min/+) mice. Myc and cyclin D1 expressions, which are transcriptional targets of beta-catenin/Tcf, increased in the adenomatous lesions. Furthermore, beta-catenin/Tcf reporter transgenic mice with Apc(Min) allele showed higher levels of the transcriptional activity of beta-catenin/Tcf in the gastric tumors. We also treated Apc(Min/+) and wild-type mice with N-methyl-N-nitrosourea (MNU), an alkylating agent that induces adenomas and adenocarcinomas in the stomach. Consequently, MNU-treated Apc(Min/+) mice significantly enhanced the tumor development in comparison with Apc(Min/+) mice or MNU-treated wild-type mice. Several gastric tumors in MNU-treated Apc(Min/+) mice showed invasion into the submucosal layer. These results indicate that the Apc/beta-catenin pathway may play an important role in at least subset of gastric carcinomas. In addition, Apc(Min/+) mice combined with MNU could be a useful short-term model to investigate multistage carcinogenesis in the stomach.

Direct binding of Cu(II)-complexes of oxicam NSAIDs with DNA backbone

Drugs belonging to the non-steroidal anti-inflammatory drug group (NSAID) are not only used as anti-inflammatory and analgesic agents, but also exhibit chemopreventive and chemosuppressive effects on various cancer cell lines. They exert their anticancer effects by inhibiting both at the protein level and/or at the transcription level. Cu(II) complexes of these NSAIDs show better anti-cancer effects than the bare drugs. Considering the above aspects, it is of interest to see if Cu(II) complexes of these drugs can exert their effects directly at the DNA level. In this study, we have used UV-Vis spectroscopy to characterize the complexation between Cu(II) and two NSAIDs belonging to the oxicam group viz. piroxicam and meloxicam, both of which exhibit anticancer properties. For the first time, this study shows that, Cu(II)-NSAID complexes can directly bind with the DNA backbone, and the binding constants and the stoichiometry or the binding site sizes have been determined. Thermodynamic parameters from van't Hoff plots showed that the interaction of these Cu(II)-NSAID complexes with ctDNA is an entropically driven phenomenon. Circular dichroism (CD) spectroscopy showed that the binding of these Cu(II)-NSAIDs with ctDNA result in DNA backbone distortions which is similar for both Cu(II)-piroxicam and Cu(II)-meloxicam complexes. Competitive binding with a standard intercalator like ethidium bromide (EtBr) followed by CD as well as fluorescence measurements indicate that the Cu(II)-NSAID complexes could intercalate in the DNA.

Interaction of oxicam NSAIDs with DMPC vesicles: differential partitioning of drugs

Small unilamellar vesicles (SUVs) formed by the dimyristoylphosphatidylcholine (DMPC), a phospholipid; serve as a membrane mimetic system that can be used to study the effect of absence of net surface charges on drug-membrane interaction. The targets of non-steroidal anti-inflammatory drugs (NSAIDs) are cyclooxygenases, which are membrane active enzymes. Hence, to approach their targets NSAIDs have to pass different bio-membranes. Different membrane parameters are expected to guide the first level of interaction of these drugs before they are presented to their targets. Our earlier studies have demonstrated the crucial role of surface charges of membrane mimetic systems like micelles and mixed micelles on the interaction of oxicam NSAIDs. In order to see whether net surface charges of membranes are essential for the interaction of oxicam NSAIDs, we have studied the incorporation of two oxicam NSAIDs, viz., piroxicam and meloxicam in DMPC vesicles using the intrinsic fluorescence properties of the drugs. To see whether different prototropic forms of the drugs can interact with DMPC vesicles, studies were carried out under different pH conditions. Transmission electron microscopy (TEM) was used to characterize the SUVs those were formed at different pH values. Steady state fluorescence anisotropy measurements show that both forms of the two drugs, viz., global neutral and anion can be incorporated into the DMPC vesicles. Partition coefficient (KP) between DMPC and the aqueous buffer used has been calculated in all cases from fluorescent intensity measurements. The KP values for the neutral and anionic forms of piroxicam are 219.0 and 25.8, respectively, and that for meloxicam are 896.7 and 110.2, respectively. From the KP values it is evident that irrespective of the nature of the prototropic forms, meloxicam has a higher KP value than piroxicam. This correlates with the previously calculated log KP values between n-octanol and aqueous phase, which demonstrates that in absence of net surface charges of DMPC vesicles the hydrophobic interaction is the principal driving force for incorporation. Our results imply that for bio-membranes having no net surface charges hydrophobic effect plays a principal role to guide these NSAIDs to their targets.

Effect of counterion on the structural switchover and binding of piroxicam with sodium dodecyl sulfate (SDS) micelles

Addition of an electrolyte such as NaCl to ionic micelles such as sodium dodecyl sulfate (SDS) alters the ionic atmosphere of the bulk solvent, thereby changing both the micellar properties and the interaction pattern of micelles with a molecule in the solvent. In this study, we show how added NaCl in the presence of SDS micelles modulates the surface charge of the micelles, which in turn fine-tunes the switchover equilibrium between anionic and global neutral forms of piroxicam. The presence of salt alters the CMC and aggregation number of SDS micelles. The binding of the global neutral form of piroxicam with SDS is found to be strongly modulated by the presence of counterion in the bulk solvent.

Mechanism of interaction of the non-steroidal antiinflammatory drugs meloxicam and nimesulide with serum albumin

The mechanism of interaction of the non-steroidal antiinflammatory drugs meloxicam and nimesulide with human and bovine serum albumin has been studied using fluorescence spectroscopy. There was only one high affinity site on serum albumin for both the drugs with association constants of the order of 10(5). Negative enthalpy (DeltaH(0)) and positive entropy (DeltaS(0)) values in the case of both meloxicam and nimesulide showed that both hydrogen bonding and hydrophobic interactions play a role in the binding of these drugs. Binding studies in the presence of the hydrophobic probe 1-anilinonaphthalene-8-sulfonate (ANS) showed that the binding of meloxicam and nimesulide to serum albumin involves predominantly hydrophobic interactions. Stern-Volmer analysis of the quenching data showed that quenching is highly efficient and that the tryptophan residues in hydrophobic regions of the proteins are fully exposed to the drugs. Thus these drugs are bound to albumin by hydrophobic interactions as well as hydrogen bonding at a site, which is close to the tryptophan residues. An increase of the pH and ionic strength caused an increase in the concentration of free drug, although the effect was not very significant.

Comparison of the effects of the chemopreventive agent resveratrol and its synthetic analog trans 3,4,5,4'-tetramethoxystilbene (DMU-212) on adenoma development in the Apc(Min+) mouse and cyclooxygenase-2 in human-derived colon cancer cells

Naturally occurring molecules with putative cancer chemopreventive properties such as the phytoalexin resveratrol (3,5,4'-trihydroxystilbene) are lead molecules that guide the design of novel agents with improved pharmacologic properties. The synthetic resveratrol analog 3,4,5,4'-tetramethoxystilbene (DMU-212) has been shown to possess stronger antiproliferative properties in human colon cancer cells than resveratrol. We tested the hypothesis that DMU-212 is also a more potent inhibitor of adenoma development in the Apc(Min+) mouse, a model of human intestinal carcinogenesis. Apc(Min+) mice received either stilbene derivative with the diet (0.2%), and adenomas were counted after experiments were terminated. Resveratrol and DMU-212 decreased adenoma load by 27% and 24%, respectively, compared to untreated controls. Cyclooxygenase (COX) enzymes are important mechanistic targets of resveratrol, and we investigated whether DMU-212 interferes with the expression and activity of COX in human colon cells. Incubation of HCA-7 cancer cells for 24-96 hr with either stilbene derivative (1-50 microM) decreased prostaglandin E-2 (PGE-2) production, but only resveratrol decreased COX-2 protein expression. In mice, which received either stilbene derivative (0.2%) for 3 weeks with their diet, PGE-2 levels in the intestinal mucosa were reduced by between 45% and 62% compared to mice on control diet. While resveratrol inhibited enzyme activity in purified COX preparations, DMU-212 failed to do so. The PGE-2 decrease seen with DMU-212 in cells and in vivo is probably mediated via its metabolites. The results suggest that alteration of the resveratrol molecule to generate DMU-212 does not abrogate its ability to decrease adenoma number in Apc(Min+) mice or to interfere with PGE-2 generation in cells.

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.

Cyclooxygenase Isozymes: The Biology of Prostaglandin Synthesis and Inhibition

Nonsteroidal anti-inflammatory drugs (NSAIDs) represent one of the most highly utilized classes of pharmaceutical agents in medicine. All NSAIDs act through inhibiting prostaglandin synthesis, a catalytic activity possessed by two distinct cyclooxygenase (COX) isozymes encoded by separate genes. The discovery of COX-2 launched a new era in NSAID pharmacology, resulting in the synthesis, marketing, and widespread use of COX-2 selective drugs. These pharmaceutical agents have quickly become established as important therapeutic medications with potentially fewer side effects than traditional NSAIDs. Additionally, characterization of the two COX isozymes is allowing the discrimination of the roles each play in physiological processes such as homeostatic maintenance of the gastrointestinal tract, renal function, blood clotting, embryonic implantation, parturition, pain, and fever. Of particular importance has been the investigation of COX-1 and -2 isozymic functions in cancer, dysregulation of inflammation, and Alzheimer's disease. More recently, additional heterogeneity in COX-related proteins has been described, with the finding of variants of COX-1 and COX-2 enzymes. These variants may function in tissue-specific physiological and pathophysiological processes and may represent important new targets for drug therapy.