Expression of ornithine decarboxylase in precancerous and cancerous gastric lesions

AIM

To investigate the expression of ornithine decarboxylase (ODC) in precancerous and cancerous gastric lesions.

METHODS

We studied the expression of ODC in gastric mucosa from patients with chronic superficial gastritis (CSG, n=32), chronic atrophic gastritis [CAG, n=43; 15 with and 28 without intestinal metaplasia (IM)], gastric dysplasia (DYS, n=11) and gastric cancer (GC, n=48) tissues using immunohistochemical staining. All 134 biopsy specimens of gastric mucosa were collected by gastroscopy.

METHODS

The positive rate of ODC expression was 34.4%, 42.9%, 73.3%, 81.8% and 91.7% in cases with CSG, CAG without IM, CAG with IM, DYS and GC, respectively (P<0.01), The positive rate of ODC expression increased in the order of CSG < CAG (without IM) < CAG (with IM) < DYS and finally, GC. In addition, ODC positive immunostaining rate was lower in well-differentiated GC than in poorly-differentiated GC (P<0.05).

CONCLUSION

The expression of ODC is positively correlated with the degree of malignity of gastric mucosa and development of gastric lesions. This finding indicates that ODC may be used as a good biomarker in the screening and diagnosis of precancerous lesions.

Telomerase expression in lung preneoplasia and neoplasia

Telomeres are specialized structures at eukaryotic chromosomes ends, which role is to prevent them from degradation, end to-end fusion and rearrangement. However, they shorten after each cellular division because of an incomplete DNA replication, acting in normal somatic cells as a mitotic clock for permanent proliferation arrest or senescence entry. Short telomeres are perceived as damaged DNA leading to p53/ATM pathway activation. In tumoral cells, a ribonucleoprotein complex termed telomerase enables telomere elongation. This complex, composed of 2 main components, the telomerase RNA component or hTR, the RNA template for telomere synthesis, and telomerase reverse transcriptase, the catalytic subunit, is reactivated in the majority of cancers, including those of the lung. In this review, we briefly present the main results on telomerase expression in various histological types of lung carcinoma and in bronchial carcinogenesis along with telomere attrition. Inhibition of one of the main components of the enzyme or limitation of telomere access by telomerase represent novel targets for cancer therapies and chemoprevention in high risk patients of lung cancer.

Cyclooxygenase-2 expression induces genomic instability in MCF10A breast epithelial cells

BACKGROUND

Cyclooxygenase-2 (COX-2) is induced in many breast cancers and COX-2 expression correlates with a worse outcome in the clinic. We hypothesized that the induction of genomic instability is a major mechanism through which COX-2 contributes to breast cancer progression.

METHODS

We transfected a normal immortalized breast epithelial cell line of Basal B subtype, MCF10A, with the pSG5-COX-2 vector and established the stably transfected cell line MCF10A/COX-2. We analyzed the genomic instability phenotype by chromosomal analysis of metaphase-arrested MCF10A and MCF10A/COX-2 cells after Giemsa staining. Groups were compared using chi(2) tests. To investigate the DNA damage checkpoint signaling, we analyzed the phosphorylation status of CHK1 protein with a phospho-specific antibody.

RESULTS

Cytogenetic analysis of early passage transfected cells showed that COX-2 expression increased genomic instability compared with the MCF10A cells transfected with a luciferase vector alone. COX-2 overexpression was associated with a significant increase in chromosomal aberrations (fusions, breaks, and tetraploidy). There was a statistically significant increase in the number of polyploid cells in the COX-2 transfected cells versus the control (P=0.004). We also found that an inhibitory CHK1 phosphorylation at Ser-280 was dramatically increased upon COX-2 overexpression in MCF10A cells, thus explaining the mechanism of inactivation of an important cell cycle checkpoint. Further analysis of the MCF10A/COX-2 cells showed that these cells have acquired a premalignant phenotype characterized by a morphological transformation, a resistance to anoikis, a reduced requirement of epidermal growth factor for growth in culture, but their inability to establish tumors in a nude mouse model of malignancy.

CONCLUSION

We found that COX-2 expression in MCF10A breast epithelial cells confers a premalignant phenotype that includes enhanced genomic instability and altered cell-cycle regulation.

Regulation of glutathione transferase P: a tumor marker of hepatocarcinogenesis

Placental glutathione transferase (GST-P) is specifically expressed during rat haptocarcinogenesis, and has been used as a reliable tumor marker for experimental hepatocarcinogenesis in the rat. The regulation of this tumor marker gene may be associated with the process of carcinogeneisis. By elucidating the mechanisms of such tumor marker gene expression, we may shed light on the molecular mechanisms of carcinogenesis. We analyzed the regulation of the GST-P gene and found that the strong enhancer element GPE1 (GST-P enhancer-1) specifically regulates the GST-P gene by interacting with specific transcription factors in normal liver and during hepatocarcinogenesis. In particular, C/EBPalpha was required for the suppression of GST-P gene in normal liver, whereas the Nrf2/MafK heterodimer was required for the activation of this gene during hepatocarcinogenesis. In this Mini-Review, we describe the positive and negative regulatory mechanisms in the pre-cancerous and normal liver, respectively.

Autocrine motility-stimulatory pathways of oral premalignant lesion cells

Patients with premalignant oral lesions have varying levels of risk of developing oral squamous cell carcinoma (OSCC), whose aggressiveness requires increased motility. Not known is if and how premalignant oral lesion cells acquire the increased motility characteristic of OSCC. This was addressed by immunohistochemical analysis of banked premalignant lesion tissues and by functional analyses using cultures established from premalignant oral lesions and OSCC. These studies showed premalignant oral lesion cells and OSCC to be more motile than normal keratinocytes. Concomitantly, levels of ceramide were reduced. The activity of the protein phosphatase PP-2A, which restricts motility and which can be activated by ceramide, was also diminished. This was due to IL-10 released from premalignant lesion cells. Treatment with a membrane-permeable ceramide restored PP-2A activity and blocked migration. These studies show an autocrine motility-stimulatory pathway that is mediated in premalignant lesion cells by IL-10 through its reduction of ceramide levels and inhibition of PP-2A activity.

Clinical significance of high-Km 5'-nucleotidase (cN-II) mRNA expression in high-risk myelodysplastic syndrome

We analyzed cytosolic high-Km 5'-nucleotidase (cN-II) and deoxycytidine kinase (dCK) mRNA expression in bone marrow mononuclear cells (BMMNC) of patients with high-risk myelodysplastic syndrome (MDS) using quantitative real-time polymerase chain reaction (rt-PCR). At diagnosis, the cN-II mRNA expression of patients was higher than that of healthy volunteers, but the dCK mRNA expression showed no significant difference. Patients with ara-C-containing chemotherapies whose BMMNC showed a high level of cN-II expression (greater than the median value) had shorter median overall survival (15 months versus 22 months, p<0.01) and shorter median post-chemotherapy survival (10 months versus 16 months, p=0.012). These data suggest that the expression level of cN-II mRNA might be a prognostic factor of high-risk MDS.

The suppression of aberrant crypt multiplicity in colonic tissue of 1,2-dimethylhydrazine-treated C57BL/6J mice by dietary flavone is associated with an increased expression of Krebs cycle enzymes

Colorectal cancer is the second leading cause of cancer deaths worldwide with diet playing a prominent role in disease initiation and progression. Flavonoids are secondary plant compounds that are suggested as protective ingredients of a diet rich in fruits and vegetables. We here tested whether flavone, a flavonoid that proved to be an effective apoptosis inducer in colon cancer cells in culture, can affect the development of aberrant crypt foci (ACFs) in C57BL/6J mice in vivo when preneoplastic lesions were induced by the carcinogen 1,2-dimethylhydrazine (DMH). Flavone applied at either a low dose (15 mg/kg body wt per day) or a high dose (400 mg/kg body wt per day) reduced the numbers of ACFs significantly, independent of whether it was supplied simultaneously with the carcinogen (blocking group) or subsequent to the tumor induction phase (suppressing group). Proteome analysis performed in colonic tissue samples revealed that flavone treatment increased the expression of a number of Krebs cycle enzymes in the suppressing group and this was associated with reduced crypt multiplicity. It suggests that mitochondrial substrate oxidation is increased by flavone in colonic cells in vivo as already observed in HT-29 cells in vitro as the prime mechanism underlying tumor cell apoptosis induction by flavone. In conclusion, flavone reduces the number of ACFs in DMH-treated mice at doses that can be achieved for flavonoids by a diet rich in fruits and vegetables. Moreover, reduction in crypt multiplicity by flavone is most probably due to the preservation of a normal oxidative metabolism.

Promoting potential of a Jamaica quassia extract in a rat medium-term hepatocarcinogenesis bioassay

Jamaica quassia extract (JQE), a natural bittering agent, was investigated for hepatocarcinogenesis-promoting potential using a medium-term liver bioassay system. F344 male rats were given a single intraperitoneal injection of diethylnitrosamine (200mg/kg body weight) and then starting 2 weeks later, received JQE in the diet at concentrations of 500, 5000 or 30,000 ppm for 6 weeks. Animals for tumor promotion (+) and (-) controls were fed 500 ppm sodium phenobarbital (PB) and basal diet, respectively during the promotion phase in this model. All animals were subjected to two-thirds partial hepatectomy at week 3 and killed at week 8. As with the PB-promoted case, both numbers and areas of glutathione S-transferase placental form-positive liver cell foci were significantly increased by JQE at 30,000 ppm, with non-significant increases evident at 5000 ppm. The results thus indicate that JQE at high dose has promoting potential for rat hepatocarcinogenesis.

Cyclooxygenase-2 (COX-2) expression in human endometrial carcinoma and precursor lesions and its possible use in cancer chemoprevention and therapy

In recent years, the design of new antineoplastic agents that can halt the progression of human malignancies with minimal systemic damage has been at the forefront of cancer research, with cyclooxygenase-2 (COX-2) as a major target molecule. With an aim to demonstrate the expression and role of COX-2, the principal putative target of COX-2 inhibitor therapy, in endometrial adenocarcinoma (EACA) and precursor lesions, atypical complex hyperplasia (ACH) and endometrial hyperplasia (EH), an immunohistochemical (IHC) analysis of 22 primary human EACAs and 14 precursor lesions was carried out. Relevant clinicopathological data were tabulated from a random computer-generated sample of 22 primary EACA patients, treated by hysterectomy at our institution. Representative tumor sections including adjacent precursor lesions and normal endometrium (NE) were immunostained with human monoclonal anti-COX-2. Qualitative and semi-quantitative COX-2 IHC staining scores were determined based on the proportion of immunoreactive cells and the intensity of cytoplasmic COX-2 expression. Fisher's exact test and the Wilcoxon Rank Sum test were used for statistical analysis. Mean patient age was 68 years (range 51-93). All 22 EACAs were of endometrioid type, of which ten (45%) were grade I, eight (36%) grade II and four (18%) were grade III. Overall, four out of nine (44%) EHs, four out of five (80%) ACHs, and 18 out of 22 (88%) EACAs were COX-2 positive. The mean COX-2 IHC scores for EH and EACAs were 33 (SD 24.11) and 76 (SD 54.57), respectively (p = 0.022). Strong or moderate COX-2 expression was observed in 17 out of 22 (77%) adenocarcinomas as compared to two out of 14 (14%) of the precursor lesions (EH and ACH). The areas of adenomyosis were COX-2 positive, while myometrial smooth muscle and normal fallopian tube tissues stained negative for COX-2. The demonstration of frequent and strong expression of COX-2 in human EACAs supports a possible role for COX-2 inhibitors. Furthermore, an increasing expression of COX-2 from EH to invasive EACAs suggests potential usefulness of COX-2 inhibition to halt the progression of precursor lesions to invasive endometrial cancers.

Low selection of preneoplastic hepatocytes after treatment with the 2-acetylaminofluorene diet-partial hepatectomy regimen in the liver of hepatocarcinogenesis-resistant DRH strain rats

In hepatocarcinogenesis-resistant DRH rats, preneoplastic hepatocytic lesions are smaller than those of usual rats during carcinogenesis. When preneoplastic hepatocytes from DRH and Donryu (original strain of DRH) were reciprocally transplanted into the livers of DRH and Donryu treated with 2-acetylaminofluorene (2-AAF) diet/two-thirds hepatectomy (PH), the Donryu cells formed small colonies within the DRH liver, whereas the DRH cells formed large colonies within the Donryu liver. The DRH liver showed less degree of oval cell proliferation after treatment with 2-AAF and PH, and DRH hepatocytes were more resistant to the growth-inhibitory effect of 2-AAF after PH. Furthermore, DRH hepatocytes were generally resistant to cytotoxicity of hepatotoxins. The tissue environment of the DRH liver, therefore, is less effective for selective growth of preneoplastic hepatocytes during the carcinogen treatment, which is probably a major cause of the hepatocarcinogenesis-resistance in DRH rats.

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

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

Quantitative immunohistochemical detection of the molecular expression patterns in proliferative inflammatory atrophy

The proliferative inflammatory atrophy (PIA) is considered as a possible precursor of prostate intraepithelial neoplasia (PIN) or prostate cancer (PCa). In this study we assessed quantitatively the expression of AMACR, p63, COX-2, GST and iNOS in serial paraffin-embedded tissue sections obtained after radical prostatectomy of PCa patients (n = 30). The applicability of these markers to distinguish PIA, PIN and PCa was evaluated. We also compared the immunohistochemical expression profiles of AMACR, COX-2 and GST in the luminal and basal cells in lesions of PIN arisen in PIA or PIA alone. Two different patterns of COX-2 expression according to the p63 status of the basal cells were found. This observation gives us grounds to hypothesize that the diverse COX-2 patterns resulted from an initial basal cell damage which subsequently propagated to its luminal secretory cells progeny.

Detection of overexpressed COX-2 in precancerous lesions of hamster pancreas and lungs by molecular imaging: implications for early diagnosis and prevention

The enzyme cyclooxygenase-2 (COX-2) is overexpressed in many cancers, cardiovascular disease, neurodegenerative disorders, and arthritis. Selective inhibitors of COX-2 have been developed as therapeutics or preventive agents for these diseases. However, recent reports have revealed a significant increase in cardiovascular mortality in long-term users of the COX-2 inhibitors Vioxx and Celebrex, emphasizing the need for noninvasive tests that allow the identification of individuals whose COX-2 levels are overexpressed prior to assignment to treatment with these drugs. In this study, we have prepared a radioiodinated analogue of the selective COX-2 inhibitor celecoxib, and verified its binding to the COX-2 enzyme in vitro. Biodistribution studies in hamsters demonstrated significantly higher levels of radiotracer in animals treated with the tobacco carcinogen NNK in lung, pancreas, and liver. Assessment of COX-2 levels by whole-body planar nuclear imaging two hours after injection of the radiotracer was suggestive of a distinct increase in COX-2 in the pancreas and liver of a hamster treated for 10 weeks with NNK, in the lungs and liver of a second animal, and in the liver only, in two additional animals from the same treatment group. Immunostains showed selective overexpression of COX-2 in pre-neoplastic lesions of the pancreas and lungs in only those animals that showed tracer accumulation in these organs and in the livers of all NNK-treated hamsters. Immunostains for COX-1 yielded detectable reactions in the intestinal epithelium but not in pancreas, lungs, or liver, supporting the specificity of the tracer for COX-2. Our data provide proof of principle for the hypothesis that molecular imaging with radiolabeled COX-2 inhibitors can be used for the noninvasive monitoring of overexpressed COX-2 levels.

[Potentially pre-neoplasics areas in rat's liver associated to chronic use of phenobarbital]

BACKGROUND

Phenobarbital has been used in experimental models because it is an important agent of carcinogenesis promotion in the liver of rats, and it is also non-genotoxic, organ-specific and dose-dependent.

AIM

To evaluate the effects of the daily administration of phenobarbital in old rats treated with phenobarbital since their birth up to 24 months of age, in the absence of concomitant administration of chemical agents, which initiate carcinogenesis.

PATIENTS AND METHODS

A control group of male Wistar rats was fed with a basic diet and a second group was fed with the same basic diet added of 0.05% of phenobarbital, for a period of 24 months. Medium and right liver fragments were submitted to the histological processing and they were stained by hematoxiciline and eosin and were immunohystochemically colored to glutathione S-transferase placentary form.

RESULTS

Glutathione S-transferase placentary positive zones were detected in both groups and the images were analyzed concerning their number and surface extension through the technique of histometry analyses.

CONCLUSION

Chronic use of phenobarbital did not modify the number of glutathione S-transferase placentary form positive areas. Although, data indicates that glutathione S-transferase placentary form positive areas media size are increased, probably because there are an increase in their evolution capacity and irreversibility.

Enhanced expression of MMP-7 and MMP-13 in inflammatory bowel disease: a precancerous potential?

Matrix metalloproteinases (MMPs) are responsible for the turnover and degradation of extracellular matrix. They play a crucial role in the growth and migration of colorectal carcinoma cells. Colorectal carcinomas are characterized by enhanced expression of MMP-2, MMP-9, MMP-7, and MMP-13. The aim of this study was to determine the expression levels of MMP-2, MMP-9, MMP-7, MMP-13, and MMP-14 and their specific inhibitor TIMP-1 in inflammatory bowel diseases and precancerous lesions of the colon, i.e., Crohn's disease and ulcerative colitis, and in adenomatous polyps (APs) for comparison. Biopsy samples of pathological and healthy tissue were obtained from 40 patients with inflammatory bowel disease (ulcerative colitis, n = 17; Crohn's disease, n = 23) and from 19 patients with APs. mRNA was measured by quantitative real-time polymerase chain reaction to study MMP and TIMP-1 gene expression in both pathological and normal mucosal specimens. For MMP-2, MMP-9, and TIMP-1, protein expression also was quantified with sandwich enzyme-linked immunosorbent assay. In biopsy specimens of Crohn's disease and ulcerative colitis, significantly increased levels of MMP-2, MMP-7, and MMP-13 mRNA were found. MMP-2 and MMP-9 showed enhanced secretion on the protein level. AP revealed an increased transcription of MMP-7 and MMP-13 genes. MMP-14 mRNA was decreased in APs. MMPs, especially MMP-7 and MMP-13, which are expressed primarily on the tumor cell surface, are elevated in inflammatory bowel disease, which may have more chance to evolve into malignancy than normal tissue. In APs, increased expression of MMP-7 and MMP-13 may serve as an early indicator for colorectal carcinogenesis.

Altered expression of thioredoxin reductase-1 in dysplastic bile ducts and cholangiocarcinoma in a hamster model

Thioredoxin reductase 1 (TrxR) is a homodimeric selenoenzyme catalyzing thioredoxin (Trx) in an NADPH-dependent manner. With regard to carcinogenesis, these redox proteins have been implicated in cell proliferation, transformation and anti-apoptosis. In the present study, using a hamster cholangiocarcinoma (ChC) model, we evaluated the immunohistochemical expression pattern of TrxR in precancerous lesions and ChCs as well as in normal bile ducts. The goal of this study was to determine the potential role and importance of TrxR in cholangiocarcinogenesis. For the ChC model, we obtained liver tissue specimens with dysplastic bile ducts prior to the development of ChC 8 weeks after initiation of the experiment and ChC samples at 27 weeks. The immunohistochemical analysis showed diffuse cytoplasmic overexpression of TrxR in the dysplastic bile duct epithelial cells as well as in cholangiocarcinoma; this was comparable to the negative or weakly positive in normal and type 1 hyperplastic bile ducts. However, TrxR appeared to be considerably down-regulated in the ChCs when compared to the higher expression observed in the dysplastic bile ducts. Therefore, these results suggest that TrxR overexpression followed by down-regulation might be an important event in cholangiocarcinogenesis, especially at early stages including the cellular transformation of candidate bile ducts. Further studies are however required to determine whether TrxR may be a potential target molecule for chemoprevention against cholangiocarcinogenesis. In addition, the molecular mechanism as well as the importance of the loss of TrxR in the development of cholangiocarcinoma, following dysplastic transformation of bile duct cells, also remains to be clarified.

COX-2 expression during early lung squamous cell carcinoma oncogenesis

Cyclooxygenase (COX)-2 is implicated in the oncogenesis of many cancers, and COX-2 inhibitors are effective in preventing the development of tumours, such as in colon cancer. Its expression is increased in nonsmall cell lung cancer and is associated with poor prognosis. The present study assessed COX-2 expression in normal bronchial epithelium, as well as in all the putative precursors of squamous cell carcinomas. COX-2 expression was studied by immunohistochemistry in 106 biopsies collected during autofluorescence bronchoscopy in consecutive patients at high-risk for lung cancer. All biopsies corresponding to normal epithelium or low-grade lesions (lesions up to moderate dysplasia) did not show increased COX-2 expression. Lesions were positive for COX-2 in eight out of 14 severe dysplasia patients, eight out of 14 in situ carcinomas and five out of eight invasive carcinomas. A strong statistically significant difference in COX-2 expression was found between normal epithelium or low-grade lesions and high-grade lesions (severe dysplasia or worse). The positive and negative predictive values of COX-2 expression for high-grade lesion were 100% and 82.35%, respectively. In conclusion, bronchial precursors of squamous cell carcinoma showed increased cyclooxygenase-2 expression and were segregated into low- versus high-grade with a high positive predictive value. Thus, cyclooxygenase-2 appears as a potential early marker of squamous cell carcinoma.

Extracellular matrix-mediated membrane-type 1 matrix metalloproteinase expression in pancreatic ductal cells is regulated by transforming growth factor-beta1

Pancreatic ductal adenocarcinoma (PDAC) is associated with an intense fibrotic reaction around the tumor known as desmoplastic reaction. This tissue is composed of interstitial matrix, predominantly type I collagen, together with proliferating fibroblastic cells. Despite the recognized importance of tumor-stromal interactions, very little is known about the interactions among pancreatic cells, myofibroblasts, and the interstitial matrix. The current study was undertaken to test the hypothesis that the desmoplastic reaction alters PDAC gene expression and cellular behavior. Evaluation of human pancreatic specimens showed increased fibrosis and enhanced membrane type 1-matrix metalloproteinase (MT1-MMP) expression in tumor specimens compared with normal pancreas. Using an in vitro model of tumor cell-stromal interactions, type I collagen and the extracellular matrix deposited by pancreatic fibroblasts and PDAC cells regulated motility of human papillomavirus-immortalized human pancreatic ductal epithelial (HPDE) cells. These "stromal" matrices also regulated MT1-MMP expression by HPDE cells, without affecting the expression of tissue inhibitor of metalloproteinase 2. Treatment with transforming growth factor-beta1 (TGF-beta1) type I receptor kinase inhibitors and function-blocking anti-TGF-beta1 antibody abrogated matrix-mediated MT1-MMP induction. TGF-beta1 also promoted MT1-MMP-dependent migration by HPDE cells. Moreover, compared with normal tissue, there was increased TGF-beta1 signaling in grade 3 tumor specimens as shown by increased phospho-Smad2 staining. These data show that the crosstalk between cancer cells and stromal elements mediated by TGF-beta1 influences cell surface- and pericellular matrix-degrading potential in vitro and may contribute to pancreatic cancer progression in vivo.

Developmental exposure to estradiol and bisphenol A increases susceptibility to prostate carcinogenesis and epigenetically regulates phosphodiesterase type 4 variant 4

Early developmental perturbations have been linked to adult-onset prostate pathology, including excessive exposure to estrogenic compounds; however, the molecular basis for this imprinting event is not known. An important and controversial health concern is whether low-dose exposures to hormonally active environmental estrogens, such as bisphenol A, can promote human diseases, including prostate cancer. Here, we show that transient developmental exposure of rats to low, environmentally relevant doses of bisphenol A or estradiol increases prostate gland susceptibility to adult-onset precancerous lesions and hormonal carcinogenesis. We found permanent alterations in the DNA methylation patterns of multiple cell signaling genes, suggesting an epigenetic basis for estrogen imprinting. For phosphodiesterase type 4 variant 4 (PDE4D4), an enzyme responsible for cyclic AMP breakdown, a specific methylation cluster was identified in the 5'-flanking CpG island that was gradually hypermethylated with aging in normal prostates, resulting in loss of gene expression. Early and prolonged hypomethylation at this site following neonatal estradiol or bisphenol A exposure resulted in continued, elevated PDE4D4 expression. Cell line studies confirmed that site-specific methylation is involved in transcriptional silencing of the PDE4D4 gene and showed hypomethylation of this gene in prostate cancer cells. Importantly, the PDE4D4 alterations in the estrogen-exposed prostates were distinguishable before histopathologic changes of the gland, making PDE4D4 a candidate molecular marker for prostate cancer risk assessment as a result of endocrine disruptors. In total, these findings indicate that low-dose exposures to ubiquitous environmental estrogens affect the prostate epigenome during development and, in so doing, promote prostate disease with aging.

Overexpression of p16INK4 is a reliable marker of human papillomavirus–induced oral high-grade squamous dysplasia

OBJECTIVE

Human papillomavirus (HPV) infection has been implicated in the development of high-grade squamous dysplasia and carcinoma of the oral cavity in the absence of other known risk factors such as smoking. HPV-induced oral dysplasia or carcinoma may be a unique tumor entity in terms of biologic behavior and treatment decisions. In detecting such cases, most reported studies have used techniques that are less sensitive than DNA amplification. Recent reports have suggested that overexpression of the p16INK4 protein is a surrogate marker of HPV-induced high-grade dysplasia or carcinoma. However, the correlation between expression of p16INK4 and the presence of HPV DNA as determined by polymerase chain reaction (PCR) amplification has not been previously reported. The purpose of this research was to determine if immunohistochemistry for p16 would serve as a marker of HPV-associated high-grade oral squamous dysplasia.

STUDY DESIGN

Archival formalin-fixed, paraffin-embedded tissue sections from 41 cases of high-grade oral squamous dysplasia were randomly selected. Expression of p16INK4 protein was assessed by immunohistochemical analysis (16P04 Neomarkers, Fremont, CA). Strong and diffuse nuclear staining restricted to the dysplastic region in the epithelium was scored as positive for protein expression, whereas focal or weak nuclear or cytoplasmic staining was scored as negative. The presence of HPV was determined by microdissection, DNA extraction, and PCR DNA amplification using elongated primers that align with corresponding sequences of the L1 region of 23 mucosotropic HPV genotypes. The HPV type was determined by direct sequencing of the PCR product. Normal squamous epithelium was used as an internal negative control, and cases of severe cervical high-grade squamous dysplasia were used as a positive control for immunohistochemical staining and PCR.

RESULTS

The results of immunohistochemical analysis for overexpression of p16INK4 were positive in 6 of the 41 tissue sections. The results of PCR DNA amplification were also positive for these 6 sections. HPV-16 was identified in 5 of the positive cases; in the other case, the viral strain could not be determined.

CONCLUSIONS

Immunohistochemical detection of p16INK4 is a technically simple and potentially reliable assay for diagnosing cases of HPV-induced oral high-grade squamous dysplasia. Detecting such lesions may influence future therapeutic decisions.

AMACR Immunostaining is Useful in Detecting Dysplastic Epithelium in Barrett's Esophagus, Ulcerative Colitis, and Crohn's Disease

Alpha-methylacyl-CoA racemase (AMACR) catalyzes the racemization of alpha-methyl, branched carboxylic coenzyme A thioesters, and is overexpressed in a variety of neoplasms, such as prostate and colon cancer. The aim of this study was to evaluate AMACR expression in the metaplasia-dysplasia-carcinoma sequence in Barrett's esophagus (BE), ulcerative colitis (UC), and Crohn's disease (CD) and to determine whether its expression can be used to detect dysplastic epithelium in these conditions. One hundred thirty-four routinely processed biopsy and/or resection specimens from 134 patients with BE [M/F ratio: 5.7, mean age: 67 y (36 negative (intestinal metaplasia only), 14 indefinite for dysplasia (IND), 16 low-grade dysplasia (LGD), 32 high-grade dysplasia (HGD), and 36 invasive adenocarcinoma (ACA)] and 74 specimens from 74 patients with inflammatory bowel disease (IBD) [56 with ulcerative colitis, 18 with Crohn's disease, M/F ratio: 1.8, mean age: 55 y (17 negative, 7 IND, 26 LGD, 10 HGD, and 14 ACA)] were immunostained with a monoclonal AMACR antibody (p504S). The degree of cytoplasmic staining in all cases was evaluated in a blinded fashion according to the following grading system: 0, negative (0% cells positive); 1+, 1% to 10% cells positive; 2+, 10% to 50% cells positive; or 3+, >50% cells positive. In patients with BE, AMACR was not expressed in any negative foci (0%) but was significantly increased (P<0.0001) in foci of LGD (38%), HGD (81%), and ACA (72%). Three of 14 (21%) IND foci from 3 BE patients were only focally positive (grade 1: 7%, 2: 14%). However, 1 of these 3 patients had follow-up information available and had developed ACA subsequently. Similarly, in patients with IBD, AMACR was not expressed in any foci considered negative for dysplasia, but was significantly increased (P<0.0001) in foci of LGD (96%), HGD (80%), and ACA (71%). Only 1/7 (14%) IND focus from 1 patient was focally positive (grade 1). The sensitivity for the detection of LGD and HGD in BE and IBD was 38% and 81%, and 96% and 80%, respectively, for the 2 types of disorders. The specificity was 100% for both BE and IBD. AMACR is involved in the neoplastic progression in BE and IBD. The high degree of specificity of AMACR for dysplasia/carcinoma in BE and IBD suggests that it may be useful to detect neoplastic epithelium in these conditions.

Expression of human telomerase reverse transcriptase (hTERT) protein is significantly associated with the progression, recurrence and prognosis of oral squamous cell carcinoma in Taiwan

This study used an immunohistochemical technique to examine the expression of human telomerase reverse transcriptase (hTERT) protein in 82 specimens of OSCC, 116 specimens of oral epithelial dysplasia (OED), and 21 specimens of normal oral mucosa (NOM). The cytoplasmic and nuclear hTERT staining intensity (SI; 0, no staining; 1, weak; 2, moderate; 3, strong), labeling indices (LIs, defined as the percentage of positive cells in total cells), and labeling scores (LSs, defined as LI x SI) in OSCC, OED, and NOM samples were calculated and compared among groups. The correlation between the cytoplasmic or nuclear hTERT LS in OSCCs and clinicopathological parameters or survival of OSCC patients was analyzed statistically. The mean cytoplasmic hTERT LSs increased significantly from NOM (87+/-17%) through OED (95+/-18%) to OSCC samples (114+/-33%, p=0.000). The mean nuclear hTERT LSs also increased from NOM (80+/-14%) to OED (91+/-20%) and then decreased to OSCC samples (86+/-35%) with no statistically significant difference among the 3 groups. A significant correlation was found between the higher mean cytoplasmic hTERT LSs and OSCCs occurring in male patients (p=0.023), with larger tumor sizes (T3 and T4, p=0.048), with more advanced clinical stages (stages 3 and 4, p=0.033), or from patients with areca quid chewing (p= 0.029), cigarette smoking (p=0.027), or alcohol drinking habit (p=0.025). In addition, OSCC patients with nuclear hTERT LSs greater than 100% were prone to have a higher recurrence rate (p=0.044) and a lower 5-year survival rate (p=0.011). Our results indicate that the increased expression of hTERT protein is an early event in oral carcinogenesis and hTERT may be a biomarker for OSCCs. Measuring the amount of cytoplasmic or nuclear expression of hTERT in OSCC samples may predict the oral cancer progression, recurrence, and prognosis in Taiwan.

Expression of cyclooxygenase-2 is associated with p53 accumulation in premalignant and malignant gallbladder lesions

AIM: To examine the relationship between cyclooxygenase-2 (COX-2) overexpression and p53 accumulation in gallbladder carcinoma and its precursor lesions.

METHODS: Sixty-eight gallbladder tissue samples comprising 14 cases of normal gallblader epithelium, 27 cases of dysplasia (11 low-grade dysplasia and 16 high-grade dysplasia) and 27 adenocarcinomas were evaluated by immunohistochemistry for COX-2 expression and p53 accumulation. The relationship among COX-2 expression, p53 accumulation and clinicopathological characteristics was analysed.

RESULTS: COX-2 was expressed in 14.3% of normal gallbladder epithelium, 70.3% of dysplastic epitehlium, and 59.2% of adenocarcinomas. When divided into low- and high-grade dysplasia, COX-2 was positive in 5 (45.4%) cases of low-grade and 14 (87.5%) of high-grade dysplasia (P = 0.019). Accumulation of p53 was detected in 5 (31.2%) cases of high-grade dysplasia and in 13 (48.1%) of carcinomas. No p53 accumulation was found in normal epithelium or low-grade dysplasia. COX-2 overexpression was observed in 17 of 18 (94.4%) cases with p53-accumulation in comparison with 20 (40.0%) out of 50 cases without p53 accumulation (P < 0.001).

CONCLUSION: The significant differences in COX-2 expression among normal epithelium, low-grade dysplasia and high-grade dysplasia suggest that overexpression of COX-2 enzyme is an early event in gallbladder carcinogenensis. Furthermore, since accumulation of p53 correlates with COX-2 expression, COX-2 overexpression observed in gallbladder high-grade dysplasia and carcinoma might be partly due to the dysfunction of p53.

Detection of overexpressed COX-2 in precancerous lesions of hamster pancreas and lungs by molecular imaging: implications for early diagnosis and prevention

The enzyme cyclooxygenase-2 (COX-2) is overexpressed in many cancers, cardiovascular disease, neurodegenerative disorders, and arthritis. Selective inhibitors of COX-2 have been developed as therapeutics or preventive agents for these diseases. However, recent reports have revealed a significant increase in cardiovascular mortality in long-term users of the COX-2 inhibitors Vioxx and Celebrex, emphasizing the need for noninvasive tests that allow the identification of individuals whose COX-2 levels are overexpressed prior to assignment to treatment with these drugs. In this study, we have prepared a radioiodinated analogue of the selective COX-2 inhibitor celecoxib, and verified its binding to the COX-2 enzyme in vitro. Biodistribution studies in hamsters demonstrated significantly higher levels of radiotracer in animals treated with the tobacco carcinogen NNK in lung, pancreas, and liver. Assessment of COX-2 levels by whole-body planar nuclear imaging two hours after injection of the radiotracer was suggestive of a distinct increase in COX-2 in the pancreas and liver of a hamster treated for 10 weeks with NNK, in the lungs and liver of a second animal, and in the liver only, in two additional animals from the same treatment group. Immunostains showed selective overexpression of COX-2 in pre-neoplastic lesions of the pancreas and lungs in only those animals that showed tracer accumulation in these organs and in the livers of all NNK-treated hamsters. Immunostains for COX-1 yielded detectable reactions in the intestinal epithelium but not in pancreas, lungs, or liver, supporting the specificity of the tracer for COX-2. Our data provide proof of principle for the hypothesis that molecular imaging with radiolabeled COX-2 inhibitors can be used for the noninvasive monitoring of overexpressed COX-2 levels.

Functional role of matrix metalloproteinase-28 in the oral squamous cell carcinoma

The newly identified MMP-28 has been shown to be expressed in several types of carcinomas, however, its functional role in transformation events is unknown. This study was to assess whether this proteinase plays a role in oral tumor malignancy. By using RT-PCR, we found that expression of MMP-28 was significantly higher in 92 oral squamous cell carcinomas (OSCCs) (52/92, 56.5%) than in seven oral premalignant lesions (OPMLs) (0/7, 0%) (P=0.004). No statistically significant correlation was found between MMP-28 expression and tumor stage, thickness, size, and metastasis. Both mRNA and protein of MMP-28 were preferentially concentrated in OSCC specimens than in neighboring tissues as analyzed by semi-quantitative RT-PCR (P=0.015) and immunohistochemistry, respectively. Transfection of OSCC and esophageal carcinoma cell lines with MMP-28 antisense oligodeoxynucleotide (AODN) resulted in the reduced secretion of MMP-28 protein and the ability of colony formation in soft agar without affecting cell growth. Our findings show the close correlation between MMP-28 and OSCC, and support a role for MMP-28 in the anchorage-independent growth of both OSCC and esophageal carcinomas.

Preneoplastic liver cell foci expansion induced by thioacetamide toxicity in drug-primed mice

Mice primed by feeding griseofulvin or diethyl 1,4-dihydro 1,4,6-trimethyl 3,5-pyridine decarboxylate for 5 months followed by drug withdrawal for 1 month (drug-primed mice) were given thioacetamide intraperitoneally, and the livers were subsequently studied at intervals up to 7 days. The hepatocellular proliferative response was measured by immunostaining for proliferative cell nuclear antigen. Necrosis was followed by measuring ALT. Mallory bodies were identified by immunoperoxidase stains for ubiquitin and cytokeratin. Preneoplastic foci were localized using immunofluorescence stain for glutathione S-transferase (GST mu) and histochemical stain for gamma glutamyl transpeptidase (GGT). The results showed that the preneoplastic foci selectively proliferated and expanded and formed nodules as indicated by quantitation of nuclei stained positive for proliferating cell nuclear antigen after thioacetamide treatment. Data support the hypothesis that the preneoplastic foci consisted of clones of hepatocytes which preferentially express GST mu, GGT and Mallory bodies. These preneoplastic cells selectively proliferate in response to the promoter effects of necrosis-induced liver cell regeneration ("chemical partial hepatectomy").

Differential caspase-3 expression in noncancerous, premalignant and cancer tissues of stomach and its clinical implication

BACKGROUND

Caspase-3 is a critical apoptosis-promoting element but its status during stepwise gastrocarcinogenesis needs to be further clarified.

MATERIALS AND METHODS

By the use of frozen tissue microarrays constructed with the tissue spots cored from defined histological regions in tissue blocks, the pattern of caspase-3 expression in noncancerous, premalignant (atrophic gastritis and intestinal metaplasia) tissue and cancer spots were analyzed under the same experimental conditions by the methods of immunohistochemistry and mRNA-in situ hybridization.

RESULTS

Caspase-3 was expressed in all 34 of the noncancerous mucosa (100%), in 16 of the 17 premalignant tissues (94.1%) and in 15 of the 48 gastric cancers (31.3%). The incidences of caspase-3 detection were significantly different (p<0.01) between noncancerous mucosa and intestinal as well as diffuse gastric cancers.

CONCLUSION

Down-regulated caspase-3 is closely correlated with gastric cancer formation and would be a potential indicator of tumor formation and progression. Helicobacter pylori (H. pylori; Hp) infection is but not the only one element responsible to the enhanced caspase-3 expression in gastric epithelia.

COX-2 inhibitors celecoxib and rofecoxib prevent oxidative DNA fragmentation

BACKGROUND

Cyclooxygenase (COX) is the key regulatory enzyme in prostaglandin (PG) synthesis and is up-regulated in many premalignant and malignant lesions. The aim of this study was to investigate the in vitro DNA protective or damaging effects of COX-2 inhibitors using the single-cell gel electrophoresis (Comet) assay.

MATERIALS AND METHODS

Cells from miniorgan cultures of pharyngeal mucosa from 30 patients were incubated once or five times with the COX-2 inhibitors celecoxib and rofecoxib. After treatment with H2O2, DNA fragmentation was determined.

RESULTS

DNA strand-breaks were significantly reduced in cells pre-incubated with COX-2 inhibitors. Repeated incubation with celecoxib showed the strongest effect. This direct influence on DNA repair could be excluded by implementing DNA repair steps into the Comet assay.

CONCLUSION

The findings suggest that, in addition to the known influence of COX-2 inhibitors on immune surveillance, neo-angiogenesis and cell proliferation, these substances may express a direct antimutagenic effect in conditions of oxidative stress.

[Down-regulation of Caspase-3 expression in precancerous lesions and its relation to gastric carcinogenesis]

OBJECTIVE

To study the level of expression of Caspase-3 protein in precancerous lesions of stomach and its relation to gastric carcinogenesis.

METHODS

Formalin-fixed paraffin embedded tissues from 184 cases of gastric mucosa biopsy and surgically removed specimens, including gastric cancer (GC, N = 20), chronic atrophic gastritis (CAG, N = 6), atrophic gastritis with intestinal metaplasia (IM, N = 31), atrophic gastritis with dysplasia (DYS, N = 114) and normal controls (N = 13) were examined for expression of Caspase-3 protein and Ki-67 index by SABC immunohistochemistry, and for apoptosis by TdT-mediated dUTP biotin nick end labeling (TUNEL) method. Caspase-3, Ki-67 and TUNEL index were compared in different stages of gastric precancerous lesions and their correlation was analyzed.

RESULTS

The positive index of Caspase-3 protein in severe DYS (29.8% +/- 3.9%) showed no significant difference compared with that in GC (26.9% +/- 3.0%, P > 0.05), but was significantly lower than that in low (58.3% +/- 4.2%) and moderate grade DYS (50.4% +/- 4.8%), CAG (68.3% +/- 3.3%) and IM (70.9% +/- 4.3%, P < 0.05). Caspase-3 positive index was significantly correlated with that of apoptosis detected by TUNEL (r = 0.94, P < 0.05). Ki-67 index in Caspase-3 protein positive group (18.3% +/- 2.2%) was significantly lower than that in Caspase-3 negative group (48.9% +/- 3.1%, P < 0.05).

CONCLUSION

Caspase-3 protein expression was upregulated in CAG with or without IM and low or moderately low in DYS, while down-regulated in severe DYS and gastric carcinoma, and significantly positively correlated with cell apoptosis. It is suggested that down-regulated expression of Caspase-3 protein somehow contributes to gastric carcinogenesis through an imbalance between cell apoptosis and proliferation.

Dietary sphingolipids suppress a subset of preneoplastic rat liver lesions exhibiting high PTEN, low phospho-Akt and high levels of ceramide species

Rat liver glutathione-S-transferase Pi-(GST-P)-positive enzyme-altered foci (EAF) are preneoplastic lesions that develop in response to carcinogenic stress. They are often used as endpoints in e.g. chemopreventive studies. In this study we characterize a pAkt-negative/ceramide-positive (pAkt-/cer+) EAF phenotype, as defined by immunohistochemistry for pAkt and ceramide species, in diethylnitrosamine(DEN)-, phenobarbital- or aflatoxinB1-treated rats. There was a close to 100% overlap for the pAkt and the ceramide marker. Furthermore, serial sections stained for PTEN indicated a close correlation between PTEN-positive and pAkt-negative lesions in DEN-treated rats. Experiments with DEN-treated rats given sphingomyelin in the diet suggested that sphingomyelin selectively targeted these lesions. In in vitro experiments sphingosine rapidly decreased pAkt levels in hepatocytes, and in experiments with hepatocytes from DEN-treated rats sphingosine selectively killed EAF cells. Furthermore, pretreatment with antisense Akt oligonucleotides in vitro sensitized non-EAF hepatocytes, so that EAF and non-EAF cells became equally sensitive to sphingosine. It is concluded that rat liver, in response to carcinogenic stress, develops a distinct EAF phenotype exhibiting low pAkt levels and concomitant alterations in sphingolipid metabolism. Our data also suggest that pAkt-/cer+ EAF are selectively targeted by sphingolipids in the diet and that lesions with this phenotype should be of particular interest for future studies on chemopreventive effects that may affect sphingolipid metabolism.

Role of glycogen synthase kinase 3 in squamous differentiation induced by cigarette smoke in porcine tracheobronchial epithelial cells

Epidemiological evidence suggests that cigarette smoke induces squamous metaplasia in human tracheobronchial epithelium that can progress to lung squamous carcinoma. But it is not well understood how tracheobronchial epithelial cells transduce the signals that mediate cigarette smoke-induced squamous differentiation or squamous metaplasia. In the present study, we found that in vitro cigarette smoke components notably inhibited glycogen synthase kinase 3 (GSK3) and induced the expression of involucrin, a marker of squamous differentiation. The inactivation of GSK3 by two highly selective inhibitors, lithium and SB216763, also significantly enhanced involucrin expression in cultured porcine tracheobronchial epithelial cells (PTBECs). Moreover, we demonstrated that cigarette smoke components significantly promoted activator protein-1 (AP-1) binding activities to the upstream regulatory region of involucrin gene, and similar results were observed by further studies through using GSK3 inhibitors to imitate the effects of cigarette smoke components. Taken together, we conclude that GSK3 is involved in involucrin expression induced by cigarette smoke in PTBEC probably via negatively regulating AP-1 activity, implying a possible mechanism responsible for squamous differentiation induced by cigarette smoke.

Cyclooxygenase-2 (COX-2) Immunostaining Does Not Correlate With the Degree of Vulvar Neoplasia

OBJECTIVE

The cyclooxygenase-2 (COX-2) enzyme is up-regulated in inflammatory and neoplastic conditions. In the last decade, its biological role has been investigated in various pre-invasive and invasive cancers with the hope that it can serve as a target for cancer prevention and treatment.

METHODS

We evaluated the expression of COX-2 in vulvar biopsies to determine its relationship to the degree of dysplasia. COX-2 expression was studied by immunohistochemistry in 62 consecutive vulvar biopsies divided into four diagnostic groups. Group 1 included inflamed vulva (n = 14); group 2, vulvar intraepithelial neoplasia (VIN) I and VIN II (n = 20); group 3, VIN III and carcinoma in situ (n = 18); and group 4, invasive squamous cell carcinoma (n = 10). Representative sections were immunostained using polyclonal anti-COX-2 antibodies at concentration 1:25 without pretreatment. Immunostaining was scored according to the proportion of positive epithelial cells in the vulvar mucosa as 0 (no positive cells), 1(< 5% positive), 2 (6-50% positive), or 3 (> 50% positive).

RESULTS

Mean immunostaining scores were 1.6, 1.4, 0.7, and 1.2 for groups 1, 2, 3, and 4, respectively. Scores were different between the groups (chi(2) = 9.908, P = 0.019) as shown by Cochran-Mantel-Haenszel statistical analysis (modified ridit scores), but did not correlate with age or the degree of dysplasia. The strongest staining for COX-2 was in the inflammatory group.

CONCLUSION

COX-2 staining in inflamed, dysplastic, and malignant vulvar epithelium is variable but, as shown in this study, does not correlate with the degree of vulvar dysplasia or malignancy.

Celecoxib induces regression of putative preneoplastic lesions in rat liver

BACKGROUND

Celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, may reduce the risk and mortality of certain types of human cancer. The chemopreventive effect of celecoxib on preneoplastic lesions induced by chemical hepatocarcinogenesis was investigated.

MATERIALS AND METHODS

Male Sprague Dawley rats were fed a celecoxib-supplemented diet between days 18 and 26 post-initiation (1500 ppm) and sacrificed on day 26. The effects of celecoxib on proliferation, apoptosis, COX-2 activity and liver function were evaluated by immunohistochemistry, TUNEL assay, enzyme-immunoassay and spectrophotometry, respectively.

RESULTS

Celecoxib decreased, in area and number, gamma-glutamyltranspeptidase and glutathione S-transferase placental-positive lesions, below levels found after 18 days, by 55.2% and 62.2%, and by 50.5% and 71.1%, respectively, (p < 0.05). Celecoxib neither induced apoptosis nor altered the levels of prostaglandin E2, bilirubin or alanine aminotransferase in the plasma; however, proliferating cell nuclear antigen and cyclin D1 decreased by 77.7% and 94.9%, respectively, (p < 0.05).

CONCLUSION

Celecoxib regresses existing preneoplastic liver lesions through antiproliferative processes, without altering liver function.

Nitric oxide synthases are associated with bronchial dysplasia

Recent studies suggest that reactive oxygen (ROS) and nitrogen species (RNS) are highly associated with the pathogenesis of cigarette smoke related lung diseases but their role in the malignant conversion of bronchial epithelium is unclear. The immunohistochemical expression of inducible, endothelial and neuronal nitric oxide synthases (iNOS, eNOS and nNOS) and nitrotyrosine as a biomarker of oxidative/nitrosative stress was evaluated in 79 cases including 13 non-smokers, 20 smokers without chronic obstructive pulmonary disease (COPD), 22 with COPD and 24 with metaplasia-dysplasia-sequence of the bronchial epithelium. Normal lung of non-smokers was mainly negative for nitrotyrosine, while it was higher in the alveolar macrophages of cigarette smokers and COPD than in non-smokers (p=0.025, p<0.001), and in the alveolar epithelium of smokers and COPD than in non-smokers (p=0.049). There were no major differences in the nitrotyrosine immunoreactivity between the metaplastic/dysplastic lesions and bronchial epithelium of cigarette smokers. Inducible NOS and nNOS were mainly non-detectable or weak in the normal looking bronchial epithelium of smokers and COPD, whereas metaplasia and dysplasia showed positivity for iNOS (22/24) and nNOS (14/24) in the majority of cases. Strong immunoreactivity for iNOS and nNOS was also found more often in dysplastic than metaplastic (p=0.011 and p=0.049, respectively) specimens. Thus, smoking can cause protein nitration also in normal lung. Prominent iNOS and nNOS immunoreactivity in the metaplasia-dysplasia-lesions suggests a divergent role of NOSs in lung carcinogenesis.

Preferential expression of cyclooxygenase-2 in colonic-phenotype of gastric intestinal metaplasia: association with helicobacter pylori and gastric carcinoma

OBJECTIVES

Gastric intestinal metaplasia (GIM) associated with H. pylori (HP) has been considered a premalignant lesion. However, GIM phenotype associated with HP infection and gastric cancer is unclear. The expression of COX-2 in relation to GIM phenotype is also unknown.

METHODS

We evaluated cellular phenotype and COX-2 expression in the GIM from HP-positive and -negative patients from Japan in the absence of gastric cancer (n = 31) by using a colon epithelium specific monoclonal antibody (mAb Das-1) and anti-COX-2 antibody. COX-2 expression was also examined in patients with gastric cancer (n = 34), both in the cancer and in the GIM areas away from the cancer field.

RESULTS

Sixty-eight percent of HP-positive GIM reacted with mAb Das-1, whereas the reactivity in the HP-negative GIM was only 25% (P < 0.001). The COX-2 expression was present in 32% of HP-positive GIM and in only 9% of HP-negative GIM (P < 0.001). In the cancer group, COX-2 expression was localized both in the cancer area (94%) and in the GIM (82%) away from the cancer. Each of the COX-2-positive tissue was also positive to mAb Das-1.

CONCLUSION

HP infection is highly associated with the development of colonic-phenotype of GIM, and about half of them expressed COX-2. COX-2 expression was frequent in both gastric cancer and the GIM adjacent to the cancer. The results suggest that the presence of mAb Das-1 and COX-2 reactivity in the GIM identify the subgroup of patients who may be at risk for gastric cancer and may need close surveillance.

Gastric pit cell hyperplasia and glandular atrophy in carbonic anhydrase IX knockout mice: studies on two strains C57/BL6 and BALB/C

Carbonic anhydrase (CA) isoenzyme IX is a hypoxia-inducible enzyme, which is expressed in the human and rodent gastrointestinal tract and overexpressed in several different tumors. Functionally, it has probably an effect on proliferation and differentiation of gastrointestinal epithelial cells. It may also participate in gastric morphogenesis, since a recent study has shown gastric pit cell hyperplasia and glandular atrophy in CA IX-knockout mice. However, it is not known whether CA IX produces morphological changes in the gastric mucosa, which can turn into a dysplasia or malignancy in the presence of some carcinogenic factors. High-salt diet is considered such a factor which has been shown to modulate Helicobacter pylori-associated carcinogenesis. We produced two strains of CA IX-knockout mice, C57/BL6 and BALB/c, and the mice ate either standard or high-salt feed for 20 weeks. Stomach samples were collected from 40 Car 9(-/-) knockout mice and 37 wildtype littermates, and the tissue sections were examined for histology. CA IX-deficiency caused gastric pit cell hyperplasia and glandular atrophy in both BALB/c and C57/BL6 strains. Excess dietary salt had no significant effect on the severity of pit cell hyperplasia. No dysplasia was found in any of the groups. In C57/BL6 mice, CA IX-deficiency was associated with gastric submucosal inflammation. The results indicate that CA IX-deficiency provides a useful model to study the mechanisms of gastric morphogenesis and epithelial integrity. Further studies are needed to see whether CA IX has a role in the regulation of immune response. The findings suggest that although CA IX-deficiency is not a tumor-promoting factor per se, it induces glandular atrophy in the body mucosa, a lesion which is considered to be a preneoplastic alteration in the stomach.

Hypoxia induced by benign intestinal epithelial cells is associated with cyclooxygenase-2 expression in stromal cells through AP-1-dependent pathway

Cyclooxygenase-2 (COX-2) plays important roles in tumor development. Especially in the early-stage colorectal tumors, COX-2 expression is often observed in the tumor stroma. However, the mechanism regulating such stromal expression of COX-2 remains unknown. In the present study, we simulated the indirect interaction between epithelial cells and stromal cells in the process of colorectal tumor development using an in vitro co-culture model in which NIH3T3 fibroblasts were co-cultured with 'sparsely' or 'densely' populated intestinal epithelial cells, Intestine-407 as a model of premalignant or benign intestinal epithelial cells, and DLD-1 and Caco-2 as models of malignant epithelial cells. COX-2 expression in NIH3T3 fibroblasts was upregulated when co-cultured with the 'dense' epithelial cells regardless of their character. Interestingly, there was pericellular hypoxia in the vicinity of NIH3T3 fibroblasts when co-cultured with 'dense' epithelial cells, and the recovery of the partial pressure of oxygen level resulted in the reduction of enhanced COX-2 expression only in NIH3T3 fibroblasts co-cultured with 'dense' Intestine-407 cells. Furthermore, COX-2 expression was also reduced by the inhibition of transcription factor AP-1. Thus, pericellular hypoxia of the stromal cells caused by densely populated epithelial cells may be one of the potent COX-2 enhancers before completion of malignant transformation during intestinal tumor development.

Three-dimensional analysis of isolated hexosaminidase-altered aberrant crypts from colons of 1,2-dimethylhydrazine-treated rats

Aberrant crypt foci, consisting of morphologically irregular crypts, are thought to be precancerous lesions for colorectal cancers. For analysis of individual crypts, F344 rats were administered weekly subcutaneous injections of 1,2-dimethylhydrazine ten times and sacrificed at experimental weeks 10 and 20 with 5-bromo-2'-deoxyuridine (BrdU) incorporation 1 h before the sacrifice. Isolated colonic crypts were classified into hexosaminidase-altered aberrant crypts (HAACs) and hexosaminidase-preserved normal-appearing crypts (HPNCs) and stereopaired images (tilt angle, 6 degrees ) were taken with a scanning electron microscope for three-dimensional analyses. While HPNCs showed symmetrical fission at the base, HAACs exhibited abnormal budding in the middle of the crypt body. At week 10, average BrdU labeled cells per crypt for DMH-treated HPNCs and HAACs were 4.9 +/- 1.0 and 18.7 +/- 2.2 (P < 0.0001), respectively, while the value for non-treated control crypts was 14.7 +/- 0.8/crypt. BrdU-positive cell numbers per unit crypt length (100 microm) in HPNCs and HAACs were 1.75 +/- 0.37 and 5.99 +/- 0.70 (P < 0.0001), respectively, while that for the control was 6.65 +/- 0.35 (P < 0.02 vs. HAAC). At the 20-week time point, the numbers per crypt were 4.0 +/- 0.8, 10.1 +/- 1.6, and 27.4 +/- 2.4, respectively, the control value being significantly higher than the others (P < 0.0001). The figures per unit length were 1.72 +/- 0.35, 2.92 +/- 0.42, and 13.39 +/- 1.11 (P < 0.0001 vs. HAAC and HPNC), respectively. BrdU incorporating cells were distributed in the bottom third of the crypt columns in HAACs, but only 18% in the HPNCs, providing evidence of hyperplasia. HAACs could be good surrogate indicators of carcinogen exposure, at least some of which may be related to colon carcinogenesis.

Existence of no-observed effect levels for 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline on hepatic preneoplastic lesion development in BN rats

There is increasing evidence that dose-response curve of genotoxic carcinogen is nonlinear and a practical threshold dose exists. However, little is known about differences in the dose-response relationship of genotoxic carcinogen among different strain rats. Herein, we showed that low doses of genotoxic carcinogen 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx) had no effects on induction of liver glutathione S-transferase placental form (GST-P)-positive foci in both BN and F344 rats, and therefore demonstrated the existence of no-observed effect level for hepatocarcinogenicity of this genotoxic carcinogen irrespective of strains. These findings further support our notion that a practical threshold dose for MeIQx hepatocarcinogenicity exists in rats.

Quantitative determination of human telomerase reverse transcriptase messenger RNA expression in premalignant cervical lesions and correlation with human papillomavirus load

Expression of human telomerase reverse transcriptase (hTERT) messenger RNA (mRNA) and human papillomavirus (HPV)-16 load were quantified using real-time polymerase chain reaction and correlated with cytological findings and the presence of HPV infection in cervical specimens. Human telomerase reverse transcriptase mRNA expression was evaluated in 15 (20.5%) of 73 specimens of atypical squamous epithelial cells of undetermined significance, in 62 (39.7%) of 156 low-grade squamous intraepithelial lesions (LGSILs), in 49 (96%) of 51 high-grade squamous intraepithelial lesions (HGSILs), and in 9 (20%) of 45 normal samples, whereas viral load was quantified in 52 (89.6%) of 58 samples infected with HPV-16. The mean levels of hTERT mRNA expression were 0.11 in normal tissue, 0.23 in atypical squamous epithelial cells of undetermined significance, 0.75 in LGSILs, and 2.5 in HGSILs. Thus, a significant increase in hTERT mRNA expression was observed with increasing degrees of cervical dysplasia. The HPV-16 load was significantly higher in samples of HGSIL than in those of LGSILs (P < .001). A significant correlation was observed between viral load and quantitative hTERT mRNA expression (r = 0.65; P < .05). Quantitative hTERT mRNA assessment showed 96% sensitivity and 100% negative predictive value for high-grade dysplasia, whereas the specificity and positive predictive value were 72% and 36.2%, respectively. It is suggested that quantitative hTERT has a very high sensitivity and negative predictive value, whereas the observed specificity was moderate, indicating that it cannot be used as a diagnostic marker but may be an adjunct in the management of women with high-grade cervical dysplasia. However, the final diagnosis must rely on the inclusion of clinical evaluation and additional assessment data.

Hyperplastic gastric tumors with spasmolytic polypeptide-expressing metaplasia caused by tumor necrosis factor-alpha-dependent inflammation in cyclooxygenase-2/microsomal prostaglandin E synthase-1 transgenic mice

We showed recently that Helicobacter infection induces expression of cyclooxygenase-2 and microsomal prostaglandin E synthase-1 in the mouse stomach, and that transgenic mice expressing both cyclooxygenase-2 and microsomal prostaglandin E synthase-1 (K19-C2mE mice) develop hyperplastic gastric tumors with inflammatory histopathology. To investigate possible roles of proinflammatory cytokines and acquired immunity in the gastric hyperplasia of K19-C2mE mice, we introduced knockout mutations for tumor necrosis factor-alpha (TNF-alpha; Tnf), interleukin-1 receptor-alpha chain (Il1r1), and Rag2 genes, respectively. Among the compound mutants, only the Tnf (-/-) K19-C2mE mice showed significant suppression of hyperplastic tumors with reduced cell proliferation. In contrast, tumorigenesis remained unaffected in either compound mutants of K19-C2mE containing Il1r1 or Rag2 mutation, indicating that neither interleukin-1beta signaling nor T cell/B cell response was required for the development of hyperplastic tumors. Importantly, spasmolytic polypeptide/trefoil factor 2-expressing metaplasia (SPEM) in the K19-C2mE stomach was also suppressed in the Tnf (-/-) K19-C2mE mice, indicating that TNF-alpha-dependent inflammation is responsible for SPEM development. Because gastric metaplasia to the SPEM lineage is considered as a preneoplastic lesion of gastric cancer, it is possible that inhibition of TNF-alpha-dependent inflammation, together with eradication of Helicobacter, can be an effective prevention strategy for gastric cancer.

Concordance of thresholds for carcinogenicity of N-nitrosodiethylamine

Three publications on the carcinogenicity of N-nitrosodiethylamine (NDEA) in the livers of F-344 or Wistar rats were examined for concordance of the data. Two reports recorded the appearance of tumors after treatment with NDEA, although one used a different dosing schedule that included phenobarbital promotion. Two studied glutathione S-transferase-placental positive (GST-p+) foci in liver at several doses. One also analyzed DNA for adducts from NDEA. This analysis revealed that when the dose was calculated in molecules/kg/day, the thresholds for the incidence of liver tumors were different by about 1.5 orders of magnitude. But when the dose was calculated as the total cumulative dose, the thresholds for tumor appearance (about 10(20.3) molecules/kg) were in agreement within the error of calculation. Combining the data for GST-p+ foci revealed remarkable agreement between the two reports and a threshold for the appearance of these foci at about 10(19.5) molecules/kg of total cumulative dose of NDEA. DNA adducts fit an exponential curve better than a linear. GST-p+ foci and adducts from NDEA were observed at doses below the threshold dose for the appearance of tumors. These results suggest that: cumulative dose is a better metric than daily dose and that adducts and GST-p+ foci appear at doses below those at which tumors appear. These results further support the observations of the authors that thresholds for carcinogenicity of this genotoxic carcinogen exist and that adducts and altered foci appear at lower doses than the threshold for carcinogenicity.

Angiotensin-converting enzyme gene insertion/deletion polymorphism is associated with risk of oral precancerous lesion in betel quid chewers

To investigate whether angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism is related to the risk of oral precancerous lesions (OPL) in Taiwanese subjects who chew betel quid, a total of 61 betel quid chewers having OPL were compared with 61 asymptomatic betel quid chewers matched for betel quid chewing duration and dosage. The frequency of homozygote for ACE D variant is significantly higher in the case subjects than that of the controls (44.3 vs 24.6%; P=0.0108). The adjusted odds ratio of the D homozygous for the risk of OPL is 8.10 (95% confidence interval (CI)=2.04–32.19, P=0.003). In the allelic base analysis, the D allele is also significantly associated with higher risk of OPL. When grouping the study subjects by smoking status, the association between ACE I/D polymorphism and risk of OPL was only observed in nonsmokers. Our results support the theory that genetic factors may contribute to the susceptibility of OPL and suggest that smoking and genetic factors may be differently involved in the development of OPL.

Lipid peroxidation and antioxidant enzyme status in oral carcinoma patients

OBJECTIVE

To measure the lipid peroxidation and endogenous antioxidant enzyme status in oral carcinoma and the protective role of exogenous antioxidants.

MATERIAL AND METHODS

20 new cases of histologically proven oral squamous cell carcinoma, 20 of leukoplakia and 20 age and sex matched healthy conrols were included. Intra oral pH of patients and controlled were measured by quantitative litmus paper test and serum was analysed for malonialdehyde (MDA), super oxide bismutase (SOD), catalase and glutathione peroxidase (GP). Patients with leukoplakia were treated with exogenous antioxidants for 3 months and the same were reassessed.

RESULTS

Oral pH of oral cancer patients was neutral (PH-7) but that of leukoplakia and controls were mildly acidic (6.64 and 6.58 respectively). Serum malonialdehyde levels were highest in oral cancer group. With antioxidant enzymes super oxide bismutase, catalase and glutathione peroxidase different pattern was noticed. Antioxidant enzymes remained almost the same (P > 0.005 each) in patients with leukoplakia after 3 months of vitamin A,C and E. but there was marginal increase in catalase level (P<0.05).

CONCLUSION

This study shows the positive benefit of vitamin (A,C,E) and nutrition supplementation on the antioxidant enzyme defense system hence prevention of oral carcinogenesis in patients with leukoplakia.

Expression of human telomerase catalytic protein in gallbladder carcinogenesis

BACKGROUND

Telomerase catalytic subunit (hTERT) gene re-expression is a rate limiting step for the activity of telomerase, a key enzyme implicated in cellular immortalisation and transformation.

AIMS

To determine the potential role of hTERT protein in gallbladder carcinogenesis.

MATERIAL/METHODS

hTERT protein was analysed by means of immunohistochemistry in 89 gallbladder tissue samples: 16 normal epithelia, 14 reactive hyperplasias, 15 low grade dysplasias, 16 high grade dysplasias, and 28 adenocarcinomas. At least 200 nuclei were assessed for each slide and the mean number of positive signals for each nucleus was expressed as the hTERT index.

RESULTS

The mean hTERT index increased progressively with the degree of gallbladder epithelial abnormalities: from 0.03 in normal epithelia, 0.04 in hyperplastic epithelia, 0.25 in low grade dysplasia, 0.82 in high grade dysplasia, to 0.93 in adenocarcinoma. Statistical analysis revealed that three different groups of gallbladder epithelial changes can be distinguished according to the number of hTERT signals for each nucleus: (1) normal and regenerative gallbladder epithelium, (2) low grade dysplasia, and (3) high grade dysplasia and adenocarcinoma (p < 0.001).

CONCLUSIONS

The occasional presence of hTERT protein in normal and regenerative gallbladder mucosa reflects their regenerative capacity. Nevertheless, significantly higher hTERT indices in low and high grade dysplastic epithelia and in gallbladder adenocarcinomas are probably a consequence of hTERT re-expression--an early event in the multistep process of gallbladder carcinogenesis.

Suppression of renin-angiotensin system attenuates hepatocarcinogenesis via angiogenesis inhibition in rats

Recent studies have shown that the renin-angiotensin system (RAS) as well as angiogenesis is involved in tumor development. The aim of the present study was to examine the interaction of RAS, angiogenesis and a potent angiogenic factor, namely the vascular endothelial growth factor (VEGF), in the hepatocarcinogenesis process. In a diethylnitrosamine-induced rat hepatocarcinogenesis model, a clinically used angiotensin-converting enzyme inhibitor, perindopril (PE), significantly suppressed glutathione S-transferase placental form (GST-P)-positive preneoplastic lesions along with inhibition of neovascularization in the liver. The hepatic expression of VEGF was also attenuated. The degree of angiogenesis correlated well with the development of preneoplastic lesions. Our in vitro study showed that PE significantly suppressed VEGF-induced tubular formation and the migration of endothelial cells (EC), whereas it did not affect the proliferation of EC. These results suggested that RAS plays an important role in hepatocarcinogenesis, at least partly through VEGF-mediated angiogenesis.

All- trans and 9- cis retinoic acids, retinol and β-carotene chemopreventive activities during the initial phases of hepatocarcinogenesis involve distinct actions on glutathione S -transferase positive preneoplastic lesions remodeling and DNA damage

Chemopreventive activities of all-trans retinoic acid (AtRA), 9-cis retinoic acid (9cRA), retinol (ROL) and beta-carotene (betaC) were evaluated during hepatocarcinogenesis. Rats received 1 mg/100 g body wt AtRA (AtRA group), 9cRA (9cRA group), ROL (ROL group), 7 mg/100 g body wt betaC (betaC group) or corn oil (CO group, controls). Hepatocyte nodule incidence was reduced (P < 0.05) in betaC group (46%), but not (P > 0.05) in AtRA (92%), 9cRA (92%) and ROL (82%) groups, compared with the CO group (100%). Multiplicity of these preneoplastic lesions (PNL) was different (P < 0.05) between CO group (44 +/- 9) and 9cRA (11 +/- 4), ROL (7 +/- 3) and betaC (4 +/- 2) groups, except for AtRA group (27 +/- 9; P > 0.05). Number/cm(2) liver section, mean area (mm(2)) and percent liver section area occupied by total (persistent + remodeling) placental glutathione S-transferase (GST-P) positive PNL was reduced (P < 0.05) in AtRA (107 +/- 13; 0.12 +/- 0.06; 13.9 +/- 3.9), 9cRA (71 +/- 12; 0.12 +/- 0.06; 6.8 +/- 2.2), ROL (96 +/- 13; 0.11 +/- 0.22; 6.8 +/- 2.0) and betaC (106 +/- 13; 0.08 +/- 0.03; 10.8 +/- 2.5) groups compared with CO group (166 +/- 14; 0.18 +/- 0.09; 28.6 +/- 5.2). Percent of remodeling GST-P positive PNL was increased (P < 0.05) in 9cRA (92 +/- 1), ROL (96 +/- 1) and betaC (93 +/- 1) groups, but not (P > 0.05) in AtRA group (90 +/- 2), compared with the CO group (86 +/- 1). Compared with the CO group, all groups present in PNL reduced (P < 0.05) cell proliferation and no differences (P > 0.05) in apoptosis. DNA damage [comet length (mum)] was reduced (P < 0.05) in ROL (87.9 +/- 2.6) and betaC (89.2 +/- 4.0) groups, but not in AtRA (94.8 +/- 4.1) and 9cRA (94.2 +/- 1.5) groups, compared with the CO group (100.4 +/- 3.9). AtRA, 9cRA, ROL and betaC presented chemopreventive activities against hepatocarcinogenesis. These involve inhibition of cell proliferation, but not induction of apoptosis. Increased remodeling of GST-P positive PNL relates to 9cRA, ROL and betaC actions, while inhibition of DNA damage relates to ROL and betaC actions.

Cyclooxygenase-2 expression associated with severity of PanIN lesions: a possible link between chronic pancreatitis and pancreatic cancer

BACKGROUND

Cyclooxygenase-2 (COX-2) is a key modulatory molecule in inflammation and neoplasia. Increasing evidence suggests a role for COX-2 in pancreatic cancer (PAC). However, expression of COX-2 in pancreatic intraepithelial neoplasia (PanIN), the precursor lesion of PAC which is often present in chronic pancreatitis (CP), has received little attention.

METHOD

COX-2 immunostaining was performed on sections of PAC (n = 26), CP (n = 34), PanIN (n = 68) and normal pancreas (n = 11). Sections were also stained for macrophages (CD68), activated pancreatic stellate cells (alphaSMA), and collagen (Sirius Red) as markers of fibrosis. Semiquantitative scoring was based on the extent and intensity of immunostaining.

RESULTS

COX-2 expression was increased in PAC compared to normal (p = 0.02) with 89% of cases exceeding COX-2 immunostaining in normal ducts. In PanIN lesions, COX-2 expression increased with escalating severity of the PanIN change (p < or = 0.01). COX-2 expression was increased in PanIN-2/3 compared to normal pancreas and CP (p < or = 0.001). In ducts of CP, COX-2 expression did not differ from that in normal tissue. There was no association between COX-2 expression and clinicopathological variables.

CONCLUSION

The high level of COX-2 expression in PanIN lesions suggests that this enzyme could be a therapeutic target at a non-invasive stage of pancreatic carcinogenesis and feasible for chemoprevention in CP.

Down-regulation of the tumor suppressor gene C-terminal Src kinase: An early event during premalignant colonic epithelial hyperproliferation

Hyperproliferation of the premalignant epithelium is critical for colonic carcinogenesis; however the mechanisms remain largely unexplored. We report herein that prior to occurrence of neoplastic lesions in the azoxymethane-rat model of colon carcinogenesis; the tumor suppressor gene C-terminal Src kinase (Csk) was down-regulated with a concomitant increase in Src activity. Furthermore, pharmacological or genetic (RNA interference) inhibition of Csk resulted in increased proliferation in colon cancer cell lines through the mitogen-activated protein kinase dependent pathway. Thus, we demonstrate, for the first time, that Csk suppression is an important early event in colorectal cancer pathogenesis.