COX-2 expression and effects of COX-2 inhibition in colorectal carcinomas and their liver metastases

Nonsteroidal anti-inflammatory drugs are known to reduce the risk and mortality from colorectal carcinoma by inhibiting cyclo-oxygenases (COX). COX-2 expression was investigated immunohistologically in 57 patients with colorectal carcinomas and in the corresponding liver metastases using tissue microarray analysis. Ex vivo COX-2 inhibition with assessment of apoptosis was performed using precision-cut tissue slices of three human liver metastases. Following stimulation with different concentrations of the selective COX-2 inhibitor meloxicam, apoptosis was assessed immunohistochemically after 6 h and 12 h. All primary carcinomas and 56 out of the 57 liver metastases showed various degrees of cytoplasmatic COX-2 expression being with a reduction and in the liver metastases. There was a time- and concentration-dependent change in the number of apoptotic cells in tissue slices, however, this was without statistical significance. COX-2 is constantly involved in the carcinogenesis and metastatic process of colorectal cancer. The antineoplastic effect of COX-2 inhibition may be based on different pathways, including changes in sensitivity to apoptosis.

Xenobiotic metabolizing genes, meat-related exposures, and risk of advanced colorectal adenoma

OBJECTIVES

Carcinogenic action of meat-related exposures, such as heterocyclic amines (HCAs), polycyclic aromatic hydrocarbons (PAHs), and N-nitroso compounds (NOCs), might explain positive associations between red and processed meat and colorectal neoplasia. Single nucleotide polymorphisms in xenobiotic metabolizing enzyme (XME) genes could alter activation/detoxfication of these compounds.

METHODS

We evaluated interactions between several XME genes (CYP1A1, CYP1B1, CYP2A6, CYP2C9, CYP2E1, CYP3A4, EPHX1, GSTM1, GSTM2, GSTT1, NAT1, NAT2, NQO1, SULT1A1, and SULT1A2) and meat-related exposures using a pathway-based approach in 720 advanced colorectal adenoma cases of the distal colon or rectum and 746 controls from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Using meat-related databases, we estimated intake of the HCAs, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP), the PAH, benzo[a]pyrene (B[a]P), and nitrate/nitrite, as NOC precursors.

RESULTS

There were possible interactions between PhIP and CYP1B1 (P_interaction=0.019) and NQO1 (P_interaction=0.007), B[a]P and CYP1B1 (P_interaction=0.005) and CYP3A4 (P_interaction=0.021), and nitrate/nitrite and CYP1A1 (P_interaction=0.022) in relation to colorectal adenoma. However, none of these interactions were statistically significant using a false discovery rate threshold of 0.20.

CONCLUSIONS

Common variants in XME genes may modify the association of HCAs, PAHs, and nitrate/nitrite with advanced colorectal adenoma, but investigation in other populations is required, especially within consortia.

Intracellular expression of reactive oxygen species-generating NADPH oxidase NOX4 in normal and cancer thyroid tissues

NADPH oxidase 4 (NOX4) belongs to the NOX family that generates reactive oxygen species (ROS). Function and tissue distribution of NOX4 have not yet been entirely clarified. To date, in the thyroid gland, only DUOX1/2 NOX systems have been described. NOX4 mRNA expression, as shown by real-time PCR, was present in normal thyroid tissue, regulated by TSH and significantly increased in differentiated cancer tissues. TSH increased the protein level of NOX4 in human thyroid primary culture and NOX4-dependent ROS generation. NOX4 immunostaining was detected in normal and pathologic thyroid tissues. In normal thyroid tissue, staining was heterogeneous and mostly found in activated columnar thyrocytes but absent in quiescent flat cells. Papillary and follicular thyroid carcinomas displayed more homogeneous staining. The p22(phox) protein that forms a heterodimeric enzyme complex with NOX4 displayed an identical cellular expression pattern and was also positively regulated by TSH. ROS may have various biological effects, depending on the site of production. Intracellular NOX4-p22(phox) localization suggests a role in cytoplasmic redox signaling, in contrast to the DUOX localization at the apical membrane that corresponds to an extracellular H(2)O(2) production. Increased NOX4-p22(phox) in cancer might be related to a higher proliferation rate and tumor progression but a role in the development of tumors has to be further studied and established in the future.

Evaluation of immunohistochemical expression of P-glycoprotein in neoplasms of the mammary gland in bitches

The aim of the study was to investigate the P-glycoprotein expression in correlation with other neoplasm traits such as: histological type, the differentiation grade, proliferative activity, expression of the cyclooxygenase-2. Material for the investigation comprised 50 tumours of the mammary gland collected from bitches during surgical procedures performed in Warsaw Veterinary Clinics and Small Animal Clinic of the Department of Clinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences - SGGW. All together 8 adenomas, 22 complex carcinomas, 15 simple carcinomas and 5 solid carcinomas. In case of cancers, the degree of histological malignancy was established: 1st degree of histological malignancy--18 neoplasms, 2nd degree of histological malignancy--14 neoplasms and 3rd degree of histological malignancy--10 neoplasms. Evaluations were conducted with histopathological and immunohistochemical methods using suitable antibodies. Proliferative activity was highly dependent on type of the neoplasm and the degree of histological malignancy. The highest value of the mitotic index was characteristic for solid and simple cancers and neoplasms with the highest degree of histological malignancy. Results of expression of the nuclear antigen Ki-67 were similar. Expression of P-glycoprotein was revealed in all types of neoplasms. The expression of P-glycoprotein was identified in cytoplasm and cell membranes of neoplastic cells. Positive expression of P-gp was observed in 76% of cancers. Complex carcinomas were the biggest group among the cancer types which demonstrated positive reaction of P-gp. High expression of P-gp was also established in cancers with the highest degree of malignancy. In bitches aged 9 through 12 years, the cancers featuring a positive reaction of P-gp constituted the most numerous group (63.2%); on the other hand, this cancer type barely appeared in the oldest bitches (10.5%).

Expression of cyclooxygenase-2 in neoplasms of the mammary gland in bitches

The aim of the study was to investigate the cyclooxygenase-2 expression in correlation with other neoplasm traits such as: histological type, the differentiation grade, proliferative activity, estrogenic receptor, as well as Hsp70 and p53 proteins expression. Material for the investigation comprised mammary gland tumours, collected from dogs, the patients of veterinary clinics, during surgical procedures. All together 14 adenomas, 66 complex carcinomas, 47 simple carcinomas and 6 solid carcinomas were studied. Evaluations were conducted with histopathological and immunohistochemical methods using suitable antibodies. Expression of COX-2 was observed in 95% of cancers, in case of which, the complex cancers constituted the highest percentage (48.4%). The highest expression of COX-2 was revealed in simple and complex cancers and in cancers with the 3rd degree of histological malignancy. The significant correlation between expression of COX-2 and high mean value of the mitotic index was found. The high expression of COX-2 was also correlated with the expression of protein p53 and expression of the protein Hsp 70. Obtained results suggest that cyclooxygenase-2 may be a prognostic factor, but it requires detailed clinical confirmation.

The Ron receptor tyrosine kinase is not required for adenoma formation in Apc(Min/+) mice

The Ron receptor tyrosine kinase is overexpressed in approximately half of all human colon cancers. Increased Ron expression positively correlates with tumor progression, and reduction of Ron levels in human colon adenocarcinoma cells reverses their tumorigenic properties. Nearly all colon tumors demonstrate loss of the adenomatous polyposis coli (APC) tumor suppressor, an early initiating event, subsequently leading to beta-catenin stabilization. To understand the role of Ron in early stage intestinal tumorigenesis, we generated Apc-mutant (Apc(Min/+)) mice with and without Ron signaling. Interestingly, we report here that significantly more Apc(Min/+) Ron-deficient mice developed higher tumor burden than Apc(Min/+) mice with wild-type Ron. Even though baseline levels of intestinal crypt proliferation were increased in the Apc(Min/+) Ron-deficient mice, loss of Ron did not influence tumor size or histological appearance of the Apc(Min/+) adenomas, nor was beta-catenin localization changed compared to Apc(Min/+) mice with Ron. Together, these data suggest that Ron may be important in normal intestinal tissue homeostasis, but that the expression of this receptor is not required for the formation and growth of adenomas in Apc(Min/+) mice.

Signalling pathway alterations in pituitary adenomas: involvement of Gsalpha, cAMP and mitogen-activated protein kinases

Despite extensive research on sporadic pituitary adenomas, it is not yet possible to assign one protein alteration to one specific type of pituitary adenomas. Nevertheless, alterations of the cAMP pathway appear to be molecular hallmarks of most growth hormone (GH)-secreting adenomas. However, these alterations do not confer specific phenotypes to patients carrying these alterations. In this review, we summarise the literature regarding signalling alterations observed in GH-secreting adenomas. We focus on Gsalpha alterations and their possible cross-talk with the extracellular signal-related kinase (ERK)1/2 pathway. In the light of results obtained on human somatotroph adenoma cells in primary culture and on models of murine somatotroph cell lines, we postulate a crucial role for ERK1/2 in GH-secreting adenomas downstream of cAMP pathway alterations that might impact the tumoural phenotype.

Analysis of genetic variants of phosphodiesterase 11A in acromegalic patients

OBJECTIVES

Aberrant cAMP signaling is involved in the pathogenesis of somatotropinomas. The aim of the study was to screen acromegalic patients for the presence of variants of phosphodiesterase type 11A (PDE11A) gene, which have been recently identified in adrenocortical and testicular tumors.

SUBJECTS AND METHODS

We sequenced the PDE11A gene-coding region in 78 acromegalic patients and 110 controls. Immunohistochemistry for PDE11A was performed in a subgroup of adenomas and normal pituitary samples.

RESULTS

We found 15 nonsynonymous germline substitutions in 13 acromegalic patients (17%), i.e. 14 missense variants (Y727C in six, R804H in one, R867G in four, and M878V in three) and one truncating mutation (FS41X), with a prevalence only slightly higher than that observed in controls (14%). Immunohistochemistry revealed PDE11A expression higher in somatotropinomas than in normal somatotrophs, without significant difference between tumors with or without PDE11A variants, with the exception of two tumors (one with loss of heterozygosity (LOH) at the PDE11A locus and one with FS41X mutation) showing markedly reduced PDE11A staining. No significant differences in hormonal and clinical parameters between patients with or without PDE11A variants were observed, although patients with PDE11A changes showed a tendency to have a more aggressive tumor compared with patients with wild-type sequence (extrasellar extension in 69 vs 45%).

CONCLUSIONS

This study first demonstrated the presence of PDE11A variants in a subset of acromegalic patients, which was only slightly more frequent than in controls. The normal expression of the enzyme in the majority of tumor tissues together with the lack of significant clinical phenotype suggests that these variants might only marginally contribute to the development of somatotropinomas.

Cyclooxygenase-2 polymorphisms, aspirin treatment, and risk for colorectal adenoma recurrence--data from a randomized clinical trial

Cyclooxygenase-2 (COX-2) catalyzes the rate-limiting step in the production of prostaglandins, potent mediators of inflammation. Chronic inflammation plays an important role in the development and progression of colorectal cancer. Aspirin inhibits COX-2 activity and lowers the risk for colorectal adenomas and cancer. We investigated whether common genetic variation in COX-2 influenced risk for colorectal adenoma recurrence among 979 participants in the Aspirin/Folate Polyp Prevention Study who were randomly assigned to placebo or aspirin and followed for 3 years for the occurrence of new adenomas. Of these participants, 44.2% developed at least one new adenoma during follow-up. Adjusted relative risks and 95% confidence intervals (95% CI) were calculated to test the association between genetic variation at six COX-2 single-nucleotide polymorphisms and adenoma occurrence and interaction with aspirin treatment. Two single-nucleotide polymorphisms were significantly associated with increased adenoma recurrence: for rs5277, homozygous carriers of the minor C allele had a 51% increased risk compared with GG homozygotes (relative risk, 1.51; 95% CI, 1.01-2.25), and for rs4648310, heterozygous carriers of the minor G allele had a 37% increased risk compared with AA homozygotes (relative risk, 1.37; 95% CI, 1.05-1.79). (There were no minor allele homozygotes.) In stratified analyses, there was suggestive evidence that rs4648319 modified the effect of aspirin. These results support the hypothesis that COX-2 plays a role in the etiology of colon cancer and may be a target for aspirin chemoprevention and warrant further investigation in other colorectal adenoma and cancer populations.

Genetic polymorphisms in the cyclooxygenase-1 and cyclooxygenase-2 genes and risk of colorectal adenoma

PURPOSE

Cyclooxygenase (COX) enzymes, COX1 and COX2, are key in converting arachidonic acid (AA) into prostaglandins that have been associated with colorectal carcinogenesis. The aim of our study was to investigate associations of polymorphisms in COX genes, alone and in interaction with exposures known to be related to inflammation and AA metabolism, with risk of colorectal adenomas.

MATERIALS AND METHODS

In a community-, colonoscopy-based case-control study with 162 incident, sporadic colorectal adenoma cases and 211 controls, we investigated associations of two promoter polymorphisms (-842 A > G in COX1 and -765 G > C in COX2) and two polymorphisms in the 3'-UTR of COX2 (8473 T > C and 9850 A > G) with risk of adenomas. Multiple logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI) of colorectal adenoma after adjusting for potential confounders.

RESULTS

Overall, there was no evidence for an association between any of the four polymorphisms and colorectal adenomas. However, we found a statistically significant interaction between the COX2 8473 T > C polymorphism and nonsteroidal anti-inflammatory drug (NSAIDs) use (P (interaction) = 0.03): The greatest reduced risk was observed for individuals with the 8473 C variant allele who also regularly used NSAIDs (OR = 0.35, 95% CI 0.16-0.75).

CONCLUSION

These results suggest that the C allele of COX2 8473 T > C polymorphism may interact with NSAIDs to reduce risk for colorectal adenoma.

Clinical significance of kallikrein-related peptidase 7 (KLK7) in colorectal cancer

Human tissue kallikrein-related peptidases are a family of 15 secreted serine proteases, located at chromosome 19q13.4. Most of them have been reported to be potential biomarkers for several carcinomas and other diseases. Human tissue kallikrein-related peptidase 7 (KLK7) has been purified from human stratum corneum and resembles a chymotryptic endopeptidase originally called stratum corneum chymotryptic enzyme (SCCE). In this study, we examined for the first time, the prognostic value of KLK7 mRNA expression, using a semi-quantitative RT-PCR method, in 105 colorectal cancer tissues for 54 of which, paired normal colonic mucosa were available. Furthermore, we analysed the expression of KLK7 in 10 adenomas, in 18 biopsies of inflamed colon mucosa, as well as in 22 human cancer cell lines of various origin, four of them being of colon. A defined number of colon cancer samples were also examined by immunohistochemistry. KLK7 expression was higher in cancerous than in normal tissues. Less differentiated tumors of more advanced stage showed higher KLK7 expression. Follow-up analysis revealed that KLK7 was significantly associated with shorter overall survival (OS) and disease-free survival (DFS). In addition, selected colon cancer samples highly expressing KLK7 gene, showed intense immunohistochemical staining for KLK7, enhancing RT-PCR results. Present data suggest that KLK7 gene is up-regulated in colon cancer and its expression predicts poor prognosis for colon cancer patients.

[PI3K p85alpha expression and its role in the progression of colorectal cancer]

OBJECTIVE

To investigate the expression of PI3K p85alpha in normal colorectal tissue, colorectal adenoma and primary colorectal carcinoma and explore its significance in the progression of colorectal cancer.

METHODS

The expression of PI3K p85alpha was detected in 116 normal colorectal tissue, colorectal adenoma and primary colorectal carcinoma specimens using immunohistochemical staining, and the relationship between the expression of PI3K p85alpha protein and the clinicopathological factors was analyzed.

RESULTS

The positivity rates of the expression of PI3K p85alpha protein increased gradually in the progression of colorectal cancer and showed significant differences between the tissues (P<0.05). A significant difference was also noted in the positivity rates of the PI3K p85alpha expression in colorectal carcinoma tissues at different Dukes' stages (P<0.05). No obvious correlation was found between PI3K p85alpha expression and the degree of the tumor differentiation.

CONCLUSIONS

Abnormal PI3K p85alpha expression occurs in the progression of colorectal cancer in close relation to the clinical stage, and the PI3K/AKT pathway plays an important role in the progression of colorectal cancer.

Loss of expression for the Wnt pathway components adenomatous polyposis coli and glycogen synthase kinase 3-beta in parathyroid carcinomas

The development of parathyroid carcinoma has been associated with inactivating mutations of the Hyperparathyroidism type 2 (HRPT2) gene encoding parafibromin, a member of the human RNA Polymerase II-Associated Factor Complex (hPAF) and functionally linked to the Wingless type (Wnt) pathway. In this study, we characterized the expression of Wnt pathway molecules in parathyroid benign and malignant tumors. Tumors were investigated by immunohistochemistry supplemented with Western blot analyses using monoclonal antibodies. The study comprised 13 tumors from 12 cases of unequivocal parathyroid carcinoma, 18 cases of parathyroid adenoma, as well as non-tumorous parathyroid tissue. Adenomatous polyposis coli (APC) was uniformly expressed in non-tumorous parathyroid tissue and adenomas, but absent in carcinomas from 9 of 12 patients (75%). Expression of glycogen synthase kinase 3-beta (GSK3-beta) was lost in 4/12 carcinomas and in 1/18 adenomas. The loss of APC and GSK3-beta did not lead to augmentation of the Wnt target protein cyclin D1 or the Wnt oncoprotein beta-catenin. Active beta-catenin showed cytoplasmic and nuclear expression in all non-tumorous tissues and tumors. Loss of APC immunoreactivity was significantly associated with parathyroid carcinoma as compared to adenomas (p<0.001), giving a high specificity (100%) and sensitivity (75%) for the detection of parathyroid malignancy. The results suggest the involvement of Wnt-pathway members APC and GSK3-beta in parathyroid carcinoma development. In addition, APC immunohistochemistry could become a useful tool for improved recognition of parathyroid carcinoma together with immunohistochemistry for parafibromin and proliferation index. Furthermore, the involvement of APC related pathways in the disease development opens possibilities to explore therapeutic routes complementary to surgery.

Further studies support the participation of stem cells in the cell turnover of duodenal adenomas

BACKGROUND

In the normal duodenal mucosa, differentiated cells (enterocytes, goblet cells and endocrine cells) migrate from stem cells to the tip of the villi, but the lysozyme-producing Paneth cells migrate to the bottom of the crypts. The position of the Paneth cells within duodenal adenomas was investigated.

PATIENTS AND METHODS

Sections from 83 duodenal adenomas were stained with hematoxylin-eosin (H&E) and with anti-lysozyme. Mature Paneth cells were those showing coarse brightly red cytoplasmic granules in H&E stain whereas their precursors were the lysozyme-positive cells that were undetected by H&E.

RESULTS

The number of mature Paneth cells/high power field (x 40) varied in adenomas from 4 to 12 (mean 65) in H&E stain, while 32 to 62 cells/field (mean 46.5) were positive in anti-lysozyme immunostain (p < 0.05). The lysozyme-expressing cells were randomly distributed within the adenoma including the superficial cell layers.

DISCUSSION AND CONCLUSION

Since mature Paneth cells and their precursors are positioned underneath stem cells, the presence of mature Paneth cells and their lysozyme-positive precursors in the surface epithelium of duodenal adenomas would imply that stem cells might have already exfoliated. An alternative explanation would mean that mutated stem cells, anchored in the bottom of the crypts of the adenoma would redirect, in an unparalleled fashion, the ontogenetic logistics of migration for Paneth cells. This stochastic molecular behaviour would require a reversal from the pre-determined migratory flow for Paneth cells to a paradoxical migration mode for these cells (from stem cells vertically along the villus, before exfoliation). Consequently, it is not inconceivable that stem cells might participate, together with other mature cells, in the cellular turnover of duodenal adenomas. If that is the case, the duodenal adenoma emerges as a suitable model to monitor the actual fate of mutated stem cells.

Overexpression of 5-lipoxygenase in colon polyps and cancer and the effect of 5-LOX inhibitors in vitro and in a murine model

PURPOSE

Arachidonic acid metabolism via the cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) pathways modulates cell growth and apoptosis. Many studies have examined the effects of COX inhibitors on human colorectal cancer, but the role of 5-LOX in colonic cancer development has not been well studied. The purpose of this study was to evaluate the expression of 5-LOX in colonic polyps and cancer and the effect of 5-LOX inhibition on colon cancer cell proliferation.

EXPERIMENTAL DESIGN

Colonic polyps, cancer, and normal mucosa were evaluated for 5-LOX expression by immunohistochemistry. Reverse transcription-PCR was used to establish 5-LOX expression in colon cancer cells. Thymidine incorporation and cell counts were used to determine the effect of the nonspecific LOX inhibitor Nordihydroguaiaretic Acid and the 5-LOX inhibitor Rev5901 on DNA synthesis. A heterotopic xenograft model in athymic mice using HT29 and LoVo human colon cancer cells was used to evaluate the effect of the 5-LOX inhibitor zileuton on tumor growth.

RESULTS

5-LOX is overexpressed in adenomatous polyps and cancer compared with that of normal colonic mucosa. LOX inhibition and 5-LOX inhibition decreased DNA synthesis in a concentration- and time-dependent manner in the Lovo cell line (P < 0.05). Inhibition of 5-LOX in an in vivo colon cancer xenograft model inhibited tumor growth compared with that of controls (P < 0.05).

CONCLUSIONS

This study showed that 5-LOX is up-regulated in adenomatous colon polyps and cancer compared with normal colonic mucosa. The blockade of 5-LOX inhibits colon cancer cell proliferation both in vitro and in vivo and may prove a beneficial chemopreventive therapy in colon cancer.

Protective effect of Cox-2 allelic variants on risk of colorectal adenoma development in African Americans

BACKGROUND

Recent evidence indicates that single nucleotide polymorphisms (SNPs) in the Cox-2 gene may modulate the risk of colorectal adenoma development.

PATIENTS AND METHODS

We explored possible associations between Cox-2 polymorphisms and risk of adenoma development in an African American case-control study comprising 72 cases of advanced adenomas and 146 polyp-free controls. An exhaustive approach of genotyping 13 haplotype-tagging SNPs (ht SNPs) distributed over the entire COX-2 gene was used.

RESULTS

Statistically significant inverse associations were observed between the heterozygous genotypes at the 5229 G>T polymorphism in intron 5 [odds ratio (OR)=0.42; confidence interval (CI)=0.19-0.92; p=0.03] and at the 10935 A>G polymorphism in the 3' flanking region downstream from the poly A signals (OR=0.39; CI=0.18-0.83;p=0.01) and the risk for colorectal adenoma development.

CONCLUSION

The data from our pilot study suggest that allelic variants of the COX-2 gene significantly influence the risk of adenoma development in the African American population.

CYP1A2 164 A-->C polymorphism, cigarette smoking, consumption of well-done red meat and risk of developing colorectal adenomas and carcinomas

BACKGROUND

Genetic polymorphisms in metabolizing enzymes may modify the association of environmental exposure on colorectal cancer (CRC) and adenoma risk.

MATERIALS AND METHODS

One hundred and ninety-eight CRC cases, 422 adenomas (206 low-risk and 216 high-risk adenomas) and 222 controls were genotyped for the CYP1A2 164 A-->C polymorphism and questionnaires were used to assess environmental exposure.

RESULTS

The smoking parameter "current smoking" was significantly associated with CRC risk, and all the smoking parameters related to current smoking, having ever smoked or high numbers of cigarette years were significantly associated with risk of adenomas. No association was detected between red meat consumption or how well red meat was cooked and colorectal carcinogenesis. When stratifying the case groups based on CYP1A2 genotype, all the smoking parameters yielded stronger risk association in carriers of the C allele.

CONCLUSION

These findings may indicate that the association between cigarette smoking and colorectal carcinogenesis can be modified by the CYP1A2 genotype.

Ornithine decarboxylase G316A genotype is prognostic for colorectal adenoma recurrence and predicts efficacy of aspirin chemoprevention

PURPOSE

The chemopreventive activity of aspirin in colorectal neoplasia may be explained in part by its effect on polyamine metabolism. The ornithine decarboxylase (ODC) G316A polymorphism affects polyamine metabolism through altered expression of ODC. We investigated the influence of ODC G316A on the chemopreventive activity of aspirin in colorectal adenoma (CRA) recurrence.

EXPERIMENTAL DESIGN

We genotyped ODC G316A in 546 individuals in the United Kingdom Colorectal Adenoma Prevention trial of aspirin for CRA recurrence prevention and pooled our findings with data from two other randomized intervention trials.

RESULTS

The United Kingdom Colorectal Adenoma Prevention participants with homozygous ODC 316AA genotype were at reduced CRA recurrence risk [relative risk (RR), 0.43; 95% confidence interval (95% CI), 0.16-1.15], particularly if also exposed to aspirin (RR, 0.24; 95% CI, 0.03-1.71). In the pooled analysis of 2,207 individuals, those with homozygous ODC 316AA genotype were at significantly reduced CRA recurrence risk (RR, 0.68; 95% CI, 0.47-0.99). Following stratification by genotype and aspirin exposure, individuals with homozygous wild-type or heterozygous genotypes derived modest benefit from aspirin (RR, 0.85; 95% CI, 0.72-1.01), whereas in those with both ODC 316AA genotype and aspirin exposure recurrence risk was halved (RR, 0.52; 95% CI, 0.29-0.91).

CONCLUSION

The ODC G316A genotype is prognostic for CRA recurrence and predictive of an enhanced response to aspirin in preventing recurrence. This variant has the potential to be a clinically useful genetic marker to identify individuals likely to derive the greatest benefit from aspirin chemoprevention.

Optical imaging of matrix metalloproteinase-7 activity in vivo using a proteolytic nanobeacon

Matrix metalloproteinases (MMPs) are extracellular proteolytic enzymes involved in tumor progression. We present the in vivo detection and quantitation of MMP7 activity using a specific near-infrared polymer-based proteolytic beacon, PB-M7NIR. PB-M7NIR is a pegylated polyamidoamine PAMAM-Generation 4 dendrimer core covalently coupled to a Cy5.5-labeled peptide representing a selective substrate that monitors MMP7 activity (sensor) and AF750 as an internal reference to monitor relative substrate concentration (reference). In vivo imaging of tumors expressing MMP7 had a median sensor to reference ratio 2.2-fold higher than a that of a bilateral control tumor. Ex vivo imaging of intestines of multiple intestinal neoplasia (APC Min) mice injected systemically with PB-M7NIR revealed a sixfold increase in the sensor to reference ratio in the adenomas of APC Min mice compared with control intestinal tissue or adenomas from MMP7-null Min mice. PB-M7NIR detected tumor sizes as small as 0.01 cm2, and the sensor to reference ratio was independent of tumor size. Histologic sectioning of xenograft tumors localized the proteolytic signal to the extracellular matrix; MMP7-overexpressing tumors displayed an approximately 300-fold enhancement in the sensor to reference ratio compared with nonexpressing tumor cells. In APC Min adenomas, the proteolytic signal colocalized with the endogenously expressed MMP7 protein, with sensor to reference ratios approximately sixfold greater than that of normal intestinal epithelium. PB-M7NIR provides a useful reagent for the in vivo and ex vivo quantitation and localization of MMP-selective proteolytic activity.

Do stem cells participate in cell turnover in duodenal adenomas? A preliminary study on Paneth cells

BACKGROUND

In the normal duodenum, Paneth cells migrate from the stem cells downwards, towards the bottom of the crypts of Lieberkuhn.

MATERIALS AND METHODS

The spatial position of Paneth cells within the profile of histological sections was investigated with hematoxilin and eosin (H&E) in 6 duodenal adenomas; 2 of them were also immonostained with lysozyme, an enzyme present in Paneth cells.

RESULTS

In H&E stain sections, the numbers of mature Paneth cells/high power field varied from 2 to 7 (mean 4.5). In the two immunostained adenomas, the numbers of lysozyme-expressing cells/high power field were 15 and 42, respectively. The lysozyme-stained cells were present at all levels in the adenomas, including the luminal epithelial layer.

CONCLUSION

In duodenal adenomas, not all Paneth cells detected by lysozyme immunostain are apparent in H&E-stained sections, suggesting that lysozyme immunostain also detects Paneth cells precursors. Since mature Paneth cells and their precursors are positioned underneath the stem cells, it is conceivable that the Paneth cells that had reached the luminal aspect of the adenomas, were preceded by stem cells. This possibility would imply that in duodenal adenomas, the stem cells would be subjected to the same laws that orchestrate the turnover of epithelial duodenal cells, including Paneth cells and their precursors.

Independent induction of caspase-8 and cFLIP expression during colorectal carcinogenesis in sporadic and HNPCC adenomas and carcinomas

Background: TNF-Related Apoptosis Inducing Ligand (TRAIL) is a promising agent for the induction of apoptosis in neoplastic tissues. Important determinants of TRAIL sensitivity are two intracellular proteins of the TRAIL pathway, caspase-8 and its anti-apoptotic competitor cellular Flice-Like Inhibitory Protein (cFLIP). Methods: The aim of this study was to investigate basic expression of caspase-8 and cFLIP in normal colorectal epithelium (n = 20), colorectal adenomas (n = 66) and colorectal carcinomas (n = 44) using immunohistochemistry performed on both sporadic and Hereditary Non-Polyposis Colorectal Cancer (HNPCC or Lynch syndrome)-associated adenomas and carcinomas. Results: Expression of both caspase-8 and cFLIP was similar in cases with sporadic and hereditary origin. Expression of caspase-8 in colorectal adenomas and carcinomas was increased when compared to normal colon tissue (P = 0.02). Nuclear, paranuclear as well as cytoplasmic localizations of caspase-8 were detected. Immunohistochemistry revealed an upregulation of cFLIP in colorectal carcinomas in comparison to normal epithelium and colorectal adenomas (P < 0.001). A large variation in the caspase-8/cFLIP ratio was observed between the individual adenomas and carcinomas. Conclusion: Caspase-8 and cFLIP are upregulated during colorectal carcinogenesis. Upregulation of caspase-8 and/or downregulation of cFLIP may be interesting approaches to maximize TRAIL sensitivity in colorectal neoplasms.

Steroid sulfatase and sulfuryl transferase activities in human brain tumors

Neuroactive steroids (dehydroepiandrosterone, pregnenolone) and their sulfates act as modulators of glutamate and gamma-aminobutyrate type A receptors in the brain The physiological ratio of these neuromodulators is maintained by two enzymes present in the brain, namely, steroid sulfatase (STS) and steroid sulfuryl transferase (SULT). Following previous determination of their activities in monkey brains, their activities were evaluated in human brain tumors. Radioimmunoassay and GC-MS were used for determination of products. Both enzyme activities were measured in the 55 most frequent human brain tumors (glioblastomas, pituitary adenomas, meningiomas, astrocytomas). Significant differences were found in STS activity among investigated types of tumors except the pair of pituitary adenomas-glioblastomas, while significant differences were found in SULT activity among investigated types of tumors. Spontaneous tendency to form clusters was revealed when both enzyme activities were taken as coordinates. Clustering indicated an individual metabolic behavior of glioblastomas and 72.7% of pituitary adenomas. Astrocytomas, meningiomas and remaining 27.3% pituitary adenomas showed similarities in both enzymes' activities. Differences in STS and SULT activity did not depend on the sex or age of subjects.

Gastric adenomas: relationship between clinicopathological findings, Helicobacter pylori infection, APC mutations and COX-2 expression

Gastric adenomas are rare neoplastic growths characterized by localized polypoid proliferations of dysplastic epithelium that tend to progress to infiltrating adenocarcinoma. Therefore, the identification of molecular markers that could reliably recognize adenomas at risk of progression is advocated in the clinical management. In this study we investigated, in a series of gastric adenoma specimens from an area at high risk of gastric cancer, the relationship between clinicopathological characteristics of adenoma and Helicobacter pylori infection, APC mutational status, and COX-2 and the down-stream enzyme mPGES1 expression. Helicobacter pylori infection, detected in 24%, and 33% by histology and PCR analyses, respectively, did not show any relationship with growth pattern, localization, size, dysplasia grade and presence of synchronous cancer. Pathogenetic mutations of MCR region (codons 1269-1589) of the APC gene were detected only in one case corresponding to a single, small size, low grade, H. pylori-negative adenoma. The expression of COX-2 largely matched that of mPGES(1). Both were overexpressed in 79% of cases showing a relationship with high-grade dysplasia, size >10 mm and presence of a synchronous carcinoma. In conclusion, COX-2 may play a key role in the development and progression of gastric adenoma and could be an attractive target in the management of gastric adenoma at major risk of cancer development.

Matrix metalloproteinase-9, a potential biological marker in invasive pituitary adenomas

OBJECT

We analyzed MMP-9 expression using mRNA and protein level determinations and explored the possibility that matrix metalloproteinase-9 (MMP-9) is a potential biological marker of pituitary adenoma invasiveness and whether MMP-9 could be used to discriminate the extent of invasiveness among different hormonal subtypes, tumor sizes, growth characteristics, and primary versus recurrent tumors.

MATERIALS AND METHODS

73 pituitary tumor specimens were snap frozen in liquid nitrogen immediately after surgical resection. RNA and protein were extracted. MMP-9 mRNA transcripts were analyzed by quantitative RT-PCR. MMP-9 protein activity was analyzed by gelatin zymography and validated by western blot analysis. Immunohistochemistry was performed to identify the presence and localization of MMP-9 in pituitary adenomas. Statistical differences between results were determined using Student's t-test or one way ANOVA.

RESULTS

Comparing different hormonal subtypes of noninvasive and invasive pituitary tumors, MMP-9 mRNA expression was significantly increased in the majority of invasive adenomas. Considering the protein levels, our data also showed a significant increase in MMP-9 activity in the majority of invasive adenomas and these differences were confirmed by western blot analysis and immunohistochemistry. In addition, consistent differences in MMP-9 expression levels were found according to tumor subtype, tumor size, tumor extension and primary versus redo-surgery.

CONCLUSIONS

MMP-9 expression can consistently distinguish invasive pituitary tumors from noninvasive pituitary tumors and would reflect the extent of invasiveness in pituitary tumors according to tumor subtype, size, tumor extension, primary and redo surgery, even at early stages of invasiveness. MMP-9 may be considered a potential biomarker to determine and predict the invasive nature of pituitary tumors.