Altered expression of beta-catenin, E-cadherin, cycloxygenase-2, and p53 protein by ovine intestinal adenocarcinoma cells

Neoplasia-Associated Wasting Diseases with Economic Relevance in the Sheep Industry

We review three neoplastic wasting diseases affecting sheep generally recorded under common production cycles and with epidemiological and economic relevance in sheep-rearing countries: small intestinal adenocarcinoma (SIA), ovine pulmonary adenocarcinoma (OPA) and enzootic nasal adenocarcinoma (ENA). SIA is prevalent in Australia and New Zealand but present elsewhere in the world. This neoplasia is a tubular or signet-ring adenocarcinoma mainly located in the middle or distal term of the small intestine. Predisposing factors and aetiology are not known, but genetic factors or environmental carcinogens may be involved. OPA is a contagious lung cancer caused by jaagsiekte sheep retrovirus (JSRV) and has been reported in most sheep-rearing countries, resulting in significant economic losses. The disease is clinically characterized by a chronic respiratory process as a consequence of the development of lung adenocarcinoma. Diagnosis is based on the detection of JSRV in the tumour lesion by immunohistochemistry and PCR. In vivo diagnosis may be difficult, mainly in preclinical cases. ENA is a neoplasia of glands of the nasal mucosa and is associated with enzootic nasal tumour virus 1 (ENTV-1), which is similar to JSRV. ENA enzootically occurs in many countries of the world with the exception of Australia and New Zealand. The pathology associated with this neoplasia corresponds with a space occupying lesion histologically characterized as a low-grade adenocarcinoma. The combination of PCR and immunohistochemistry for diagnosis is advised.

Role of Cadherins in Cancer-A Review

Cadherins play an important role in tissue homeostasis, as they are responsible for cell-cell adhesion during embryogenesis, tissue morphogenesis, differentiation and carcinogenesis. Cadherins are inseparably connected with catenins, forming cadherin-catenin complexes, which are crucial for cell-to-cell adherence. Any dysfunction or destabilization of cadherin-catenin complex may result in tumor progression. Epithelial mesenchymal transition (EMT) is a mechanism in which epithelial cadherin (E-cadherin) expression is lost during tumor progression. However, during tumorigenesis, many processes take place, and downregulation of E-cadherin, nuclear β-catenin and p120 catenin (p120) signaling are among the most critical. Additional signaling pathways, such as Receptor tyrosine kinase (RTK), Rho GTPases, phosphoinositide 3-kinase (PI3K) and Hippo affect cadherin cell-cell adhesion and also contribute to tumor progression and metastasis. Many signaling pathways may be activated during tumorigenesis; thus, cadherin-targeting drugs seem to limit the progression of malignant tumor. This review discusses the role of cadherins in selected signaling mechanisms involved in tumor growth. The clinical importance of cadherin will be discussed in cases of human and animal cancers.

Detection of the Bacteroides fragilis toxin gene in sheep with and without small intestinal adenocarcinoma

Aims: To determine if presence of the Bacteroides fragilis toxin (bft) gene, a molecular marker of colonic carriage of entertoxigenic Bacteroides fragilis (ETBF) in humans, was associated with a finding of small intestinal adenocarcinomas (SIA) in sheep in New Zealand. Methods: Samples of jejunal tissue were collected from the site of tumours and from grossly normal adjacent tissue in 20 sheep, in different consignments, diagnosed with SIA based on gross examination of viscera following slaughter. Two jejunal samples were also collected from a control sheep in the same consignment that had no gross evidence of SIA. A PCR assay was used to detect the presence of the bft gene in the samples. Results: Of the sheep with SIA, the bft gene was amplified from one or both samples from 7/20 (35%) sheep, and in sheep that had no gross evidence of SIA the bft gene was amplified from at least one sample in 11/20 (55%) sheep (RR 0.61; 95% CI = 0.30-1.25; p = 0.34). Of 11 positive samples analysed, ETBF subtype bft-1 was detected in one, bft-2 was detected in 10, and none were bft-3. Conclusions and Clinical Relevance: There was a high prevalence of detection of the bft gene in both SIA-affected and non-affected sheep, but there was no apparent association between carriage of ETBF, evidenced by detection of the bft gene, and the presence of SIA. ETBF are increasingly implicated in the aetiology of human colorectal cancer, raising the possibility that sheep may provide a zoonotic reservoir of this potentially carcinogenic bacterium. Abbreviation: Bft: Bacteroides fragilis toxin; ETBF: Enterotoxigenic Bacteroides fragilis; SIA: Small intestinal adenocarcinoma.

Beta-catenin expression in pilomatrix carcinoma with multiple visceral metastases in a dog

Beta-catenin is a protein initially identified as a submembrane component of the E-cadherin-mediated cell-to-cell adhesion system. It plays a role as a transcriptional factor in the wingless/Wnt signalling pathway. Beta-catenin has been associated with oncogenic activity in human benign and malignant pilomatrix neoplasms where the immunohistochemical profile of β-catenin expression displayed both nuclear and cytoplasmic staining in basaloid cells. In this study, an 8-year-old female Irish setter dog was examined because of the presence of skin nodules. Tissue biopsies from different nodules were obtained and histological examination suggested a diagnosis of pilomatrix carcinoma. The dog spontaneously died after 2 months and necropsy showed multiple metastases in the nasal cavity, lungs, heart, kidney, liver and colon. Routine histopathology of metastatic sites showed features consistent with the pattern of primary neoplastic nodules. Immunohistochemical detection of β-catenin was performed in both the primary tumour and the metastases. Beta-catenin expression was located in the nuclei, cytoplasm and membrane of squamoid cells and in the cytoplasm of basaloid cells, while shadow cells were completely negative. To the best of our knowledge, these data represent the first report on the immunohistochemical expression profile of β-catenin in canine pilomatrix carcinoma.

The cancer marker neutrophil gelatinase-associated lipocalin is highly expressed in human endometrial hyperplasia

Recently, endometrial hyperplasia was identified as presenting a higher risk for progressing to endometrial carcinoma more readily than adenomyosis. The Lcn-2 gene encodes neutrophil gelatinase-associated lipocalin (NGAL), which promotes cell proliferation and serves as a cancer marker in some cancers. In our current study, we investigated the relationship between the expression of NGAL and that of pathogenic cytokines and cancer-related genes including cyclooxygenase-2 (COX-2), E-cadherin, β-catenin, and vimentin in patients with endometrial disorders. NGAL expression was examined by Western blotting, immunohistochemistry, and reverse-transcription polymerase chain reaction (RT-PCR) in hyperplasia and adenomyosis biopsy samples. Immunohistochemistry demonstrated the occurrence of NGAL in glandular epithelial cells but not in the stromal cells of hyperplasia biopsy samples. NGAL protein and mRNA expression were significantly greater in endometrial hyperplasia than in endometrial adenomyosis. Although our data showed no difference in pathogenic cytokines between patients with endometrial hyperplasia and endometrial adenomyosis, we observed high expression levels of COX-2, β-catenin, vimentin, and E-cadherin in patients with endometrial hyperplasia. NGAL mRNA expression correlated positively with COX-2 and E-cadherin mRNA expression (r = 0.41 and r = 0.57, respectively), but correlated negatively with vimentin and β-catenin mRNA expression (r = -0.42 and r = -0.61, respectively). Our data suggest that NGAL is up-regulated in patients with endometrial hyperplasia to prevent the transition from hyperplasia to carcinoma.

Ovine small intestinal adenocarcinomas are not associated with infection by herpesviruses, Helicobacter species or Mycobacterium avium subspecies paratuberculosis

Sheep in New Zealand more frequently develop small intestinal adenocarcinoma (SIA) than sheep in other countries. The reasons for this high rate of intestinal neoplasia are not known. In man, differences between countries in the incidence of neoplasia are often due to differences in the rate of infection by carcinogenic viruses or bacteria. Therefore, it was hypothesized that New Zealand sheep more frequently develop SIA as they are more frequently exposed to an infectious agent. This study compared rates of detection of herpesviruses, Helicobacter species, and Mycobacterium avium subspecies paratuberculosis (MAP) in ovine SIA to rates of detection in samples of intestine with non-neoplastic disease. These infectious agents were chosen as all three have been associated with human intestinal cancer. Microscopical examination did not reveal helical bacteria within sections of SIA or non-neoplastic jejunum. Polymerase chain reaction amplified herpesviral DNA more frequently from samples of non-neoplastic jejunum than samples of SIA. MAP DNA was not amplified from either neoplastic or non-neoplastic jejunum. These results suggest that the high rates of SIA in New Zealand sheep are not due to frequent infection by herpesviruses, Helicobacter species or MAP.

Mismatch repair protein expression in ovine intestinal adenocarcinomas

Sheep in New Zealand develop small intestinal adenocarcinomas more frequently than sheep elsewhere in the world. This high rate of neoplasm development could be due to a genetic predisposition or due to an environmental carcinogen. Differentiation between a genetic and an environmental factor is important as, if an environmental carcinogen is present, people could be exposed directly or by consuming sheep meat. In humans, germline defects in the mismatch repair (MMR) genes cause hereditary nonpolyposis colorectal cancer (HNPCC). Affected people are predisposed to neoplasm development, most commonly colonic adenocarcinomas. It was hypothesized that MMR defects are common within the New Zealand sheep flock, and these defects predispose New Zealand sheep to intestinal neoplasia. To investigate this, immunohistochemistry was used to evaluate the expression of the MMR proteins MSH2, MSH6, MLH1, and PMS2 within 49 ovine intestinal adenocarcinomas. Neoplastic cells within all sheep tumors expressed MSH2, MSH6, and MLH1. Expression of PMS2 could not be assessed, most likely because of insufficient affinity of the anti-human PMS2 antibody to ovine PMS2. The consistent expression of MSH2, MSH6, and MLH1 within the ovine intestinal adenocarcinomas does not support the hypothesis that defects in the MMR genes are common in New Zealand sheep.