Navigating the challenges of establishing a new residency program in anatomic pathology based on the Accreditation Council for Graduate Medical Education International standards in the post-Soviet era Kazakhstan: strategies and successes.

In 1991, after the dissolution of the Soviet Union, newly independent Kazakhstan faced challenges of a healthcare system in transition. Anatomic pathology practice remains one of the least developed medical specialties in Kazakhstan. Acute shortage of pathologists is a universal phenomenon. There is no subspecialty pathology practice as yet. Residency programs in anatomic pathology are found only in a few tertiary health institutions in the big cities. Nazarbayev University School of Medicine was established in 2015 to reform medical education in Kazakhstan. Prior to this time, in 2010, Nazarbayev University was established to lead higher education reforms in the country. Each school in Nazarbayev University was paired with an international partner to jump-start its trajectory to excellence. Establishing a new residency program in anatomic pathology based on a western pedagogy was a new innovation that needed multi-level stakeholder consultation and support. In partnership with the University of Pittsburgh School of Medicine and its hospital system, the University of Pittsburgh Medical Center, we established the first residency program in anatomic pathology based on the Accreditation Council for Graduate Medical Education International standards in Central Asia. We have identified 5 strategic approaches that led to our rapid success, including targeted strategic partnership; robust engagement with the local stakeholders; adoption and contextualizing of an existing pedagogy; ensuring adequate and fit-for-purpose infrastructure; and organizational restructuring and optimization. We hope that these suggestions will be translatable to help those facing the arduous but exciting task of establishing a new residency program from scratch.

Public Health Response Measures for COVID-19 in Kazakhstan.

The article describes measures developed to counter the spread of coronavirus infection in the Republic of Kazakhstan. The first cases of coronavirus disease 2019 (COVID-19) in Kazakhstan were detected on March 13, 2020, among people who arrived from Germany. After declaring the state of emergency in the country, the Ministry of Healthcare of the Republic of Kazakhstan began to formulate and implement a comprehensive package of measures aimed at slowing down and stopping the transmission of infection, preventing outbreaks, ensuring optimal care for all patients, especially the seriously ill, minimizing the negative impact of the pandemic on health systems, social services, and economic activities. Developed set of restrictive measures was approved by the Country Office of Word Health Organization (WHO) in Kazakhstan, being later adapted by the European Union (EU) countries and applied in Kyrgyzstan. In addition, article identifies Kazakhstan's experience in creating epidemiological surveillance systems, studying virus mutations, and the clinical aspects of dealing with it to combat the infection. It also indicates the impact of the epidemic on health-care workers and the development of measures to protect them, strengthening infection prevention, and control in medical organizations.

The actin-bundling protein fascin is overexpressed in inflammatory bowel disease and may be important in tissue repair.

BACKGROUND: Fascin is associated with increased cell motility in colorectal tumours but is absent from the normal colonic epithelium. We examined the expression of fascin in inflammatory bowel disease (IBD) and its location at regions undergoing restitution and regeneration. Tissue repair is essential for disease remission and we sought to determine the effects of therapeutic modalities on fascin expression and function using an in vitro model. METHODS: Immunohistochemistry was performed on colonic tissue from IBD patients to determine changes in fascin expression and distribution. A human colorectal epithelial cell line was treated with 5-aminosalicylate (a common treatment for IBD), or sodium butyrate to determine the effect on fascin expression and cell motility. RESULTS: Fascin overexpression was observed in both ulcerative colitis and Crohn's colitis and expression correlated with disease severity. Immunoreactivity was more intense and widespread in Crohn's compared to ulcerative colitis. Interestingly, highly expressing foci were consistently observed at the edges of ulcers where flattened, motile epithelial cells are actively involved in restitution, and also in areas of mucosal regeneration.5-aminosalicylate reduced fascin expression in colorectal epithelial cells and inhibited their motility. Conversely, sodium butyrate increased fascin expression and stimulated cell motility in the same cells. CONCLUSIONS: Our data shows that fascin is overexpressed in inflammatory bowel disease and its location is indicative of a role in tissue repair. Our in vitro studies show that different therapeutic modalities may have converse effects on fascin expression and may have significant consequences for disease remission and the clinical management of IBD.

Soluble IGF2 receptor rescues Apc(Min/+) intestinal adenoma progression induced by Igf2 loss of imprinting.

The potent growth-promoting activity of insulin-like growth factor-II (IGF-II) is highly regulated during development but frequently up-regulated in tumors. Increased expression of the normally monoallelic (paternally expressed) mouse (Igf2) and human (IGF2) genes modify progression of intestinal adenoma in the Apc(Min/+) mouse and correlate with a high relative risk of human colorectal cancer susceptibility, respectively. We examined the functional consequence of Igf2 allelic dosage (null, monoallelic, and biallelic) on intestinal adenoma development in the Apc(Min/+) by breeding with mice with either disruption of Igf2 paternal allele or H19 maternal allele and used these models to evaluate an IGF-II-specific therapeutic intervention. Increased allelic Igf2 expression led to elongation of intestinal crypts, increased adenoma growth independent of systemic growth, and increased adenoma nuclear beta-catenin staining. By introducing a transgene expressing a soluble form of the full-length IGF-II/mannose 6-phosphate receptor (sIGF2R) in the intestine, which acts as a specific inhibitor of IGF-II ligand bioavailability (ligand trap), we show rescue of the Igf2-dependent intestinal and adenoma phenotype. This evidence shows the functional potency of allelic dosage of an epigenetically regulated gene in cancer and supports the application of an IGF-II ligand-specific therapeutic intervention in colorectal cancer.

Adult leydig cell tumors of the testis caused by germline fumarate hydratase mutations.

CONTEXT: Leydig cell tumors (LCTs) are the most common non-germ-cell neoplasms of the testis. LCTs are often hormonally active and can result in precocious virilization or in adult feminization. We identified an LCT in an affected individual from a kindred with hereditary leiomyomatosis and renal cell cancer (HLRCC) and a germline fumarate hydratase (FH) mutation (N64T). OBJECTIVE: Our objective was to investigate the role of FH mutations in predisposition to LCTs. DESIGN: We tested for pathogenic effects of the N64T mutation and screened an additional 29 unselected adult LCTs for FH alterations. We also tested these LCTs for mutations in two genes, the LH/choriogonadotropin receptor (LHCGR) and the guanine nucleotide-binding protein alpha (GNAS) that had been implicated in LCT tumorigenesis. RESULTS: No mutations were found in GNAS, and one tumor had a LHCGR somatic substitution. In addition to the HLRCC case with the N64T germline FH mutation, we identified one other LCT with a previously unreported FH mutation (M411I). Both LCTs from these patients showed loss of the wild-type FH allele. Immunohistochemical and in situ hybridization analyses demonstrated activation of the hypoxia/angiogenesis pathway not only in the tumors belonging to the FH mutation carriers but also in several other mutation-negative LCTs. CONCLUSIONS: Our study shows that some LCTs are caused by FH mutations and represents one of the first reports of germline mutations in any type of adult testicular tumor.

A multicenter Phase I gene therapy clinical trial involving intraperitoneal administration of E1A-lipid complex in patients with recurrent epithelial ovarian cancer overexpressing HER-2/neu oncogene.

PURPOSE: HER-2/neu oncogene is overexpressed in 10-30% of epithelial ovarian cancers and is associated with a poor prognosis. The E1A gene product of adenovirus type 5 down-regulates HER-2/neu and causes tumor regression in animal models. In the current study, we sought to determine the toxicity and biological activity of E1A-lipid complex in ovarian cancer patients. EXPERIMENTAL DESIGN: A Phase I trial involving intraperitoneal (i.p.) administration of E1A-lipid complex was initiated in ovarian cancer patients to assess biological activity (E1A gene transfer/transcription/translation and HER-2/neu expression) and to determine the maximum tolerated dose. Successive cohorts received E1A-lipid complex at doses of 1.8, 3.6, and 7.2 mg DNA/m(2), given as weekly i.p. infusions for 3 of 4 weeks (each cycle) up to a maximum of six cycles. Peritoneal fluid was sampled at baseline and twice monthly for cellularity, cytology, CA-125, and biological activity RESULTS: Fifteen patients, with a median age of 57 years (range, 43-81) were recruited. Three (1.8 mg DNA/m(2)), 4 (3.6 mg DNA/m(2)), and 8 patients (7.2 mg DNA/m(2)) received i.p. E1A. A total of 91 infusions (range, 1-18) was administered. Abdominal pain was the dose-limiting toxicity, and the maximum-tolerated dose was 3.6 mg DNA/m(2). E1A gene transfer and expression was observed in all of the patients and at all of the dose levels. HER-2/neu down-regulation could be demonstrated in the tumor cells of 2 patients (18%). There was no correlation between dose and biological activity. CONCLUSIONS: I.P. EIA-lipid complex gene therapy is feasible and safe. Future studies, either alone or in combination with chemotherapy, particularly in patients with minimal residual disease, should be evaluated.

Laryngeal epithelial defenses against laryngopharyngeal reflux: investigations of E-cadherin, carbonic anhydrase isoenzyme III, and pepsin.

OBJECTIVES: This is the third annual report of an international research network studying the cellular impact of laryngopharyngeal reflux (LPR) on laryngeal epithelium. The objective of this study was to investigate the presence of E-cadherin (epithelial cadherin; the intercellular junctional complex protein) in relation to the presence of (intracellular) pepsin and carbonic anhydrase isoenzyme III (CAIII). METHODS: Fifty-four laryngeal biopsy specimens from 18 LPR patients were studied by immunohistochemistry and Western blotting for pepsin, E-cadherin, and CAIII. These data were compared to those from normal control subjects analyzed in another research study. RESULTS: Intracellular pepsin was detected in LPR patients, but not in controls. E-cadherin expression was reduced in patients with LPR. Carbonic anhydrase III expression was not found in the vocal fold or in the majority of samples taken from the ventricle of LPR patients and was inversely associated with E-cadherin membranous expression. CONCLUSIONS: The findings of depleted E-cadherin and CAIII and the presence of pepsin appear to correlate with LPR. The reduced protective response indicated by the reduced expression of CAIII may play an important role in the disruption of the intercellular barrier associated with the down-regulation of E-cadherin.

Cytoskeletal network in colon cancer: from genes to clinical application.

Colorectal cancer arises from well-defined sequential steps characterised by distinct genetic events. Abnormalities in the expression and functional activity of cell adhesion molecules are implicated in the development and progression of the majority of colorectal cancers. Intercellular (e.g. E-cadherin/catenin complex) and cell-matrix (e.g. integrins) adhesion molecules are more than just cementing substances but regulate cell polarity, differentiation, proliferation, migration and invasion. Many of these cellular events are mediated through their intimate association with the actin cytoskeletal network. A dynamic actin cytoskeleton characterises normal epithelial cells and polymerisation and depolymerisation of actin filaments enables cell shape to change during migration and mitosis. In colorectal cancer, cells lose actin cytoskeletal organisation and normal cell adhesion when they become invasive. Future investigations should allow the unravelling of new cytoskeletal network functions in tumour biology and may lead to the development of novel therapeutic strategies based on the manipulation of its associated molecules.

Beta-catenin expression and allelic loss at APC in sporadic colorectal carcinogenesis.

beta-catenin is involved in E-cadherin-mediated cell adhesion, intracellular signal transduction, and also interacts with adenomatous polyposis coli (APC) protein. We previously found that 31% of colorectal adenomas and 84% of carcinomas showed reduced membranous staining of beta-catenin, while 46% of adenomas and 79% of carcinomas displayed beta-catenin nuclear expression. Importantly, a reciprocal relationship between reduced membranous and increased nuclear beta-catenin expression was demonstrated in the development from adenoma to carcinoma. To clarify whether this relates to an abnormality of the APC gene ( APC), we have now studied allele loss in microdissected tissues from 74 adenomas and 21 carcinomas (sporadic cases, previously immunostained for beta-catenin) by analysis of the microsatellites D5S346, D5S82 and D5S299. Fifty-five tumors (57.8%) showed allele loss at APC (no difference between adenomas and carcinomas). Thirty-one of these 55 (31/55, 56.4%) displayed both increased nuclear localization and reduced membranous staining of beta-catenin, and thirteen tumors (13/55, 23.6%) manifested either nuclear expression without changes in membranous expression or reduced membranous staining without nuclear expression (9 and 4 cases, respectively), while 11 (11/55, 20.0%) preserved normal membranous expression. Adenomas and carcinomas showing both nuclear and reduced membranous expression of beta-catenin, compared with those with normal membranous expression, tended to show allele loss ( P<0.01). In addition, 24 (24/95, 25.6%) tumors showed a change in the pattern of beta-catenin expression, but did not exhibit allele loss. These results suggest that although there may be a number of mechanisms responsible for changes in beta-catenin expression in colorectal tumors, dysfunction of APC may be the major cause of this phenomenon.

Cell biology of laryngeal epithelial defenses in health and disease: further studies.

This is the second annual report of an international collaborative research group that is examining the cellular impact of laryngopharyngeal reflux (LPR) on laryngeal epithelium. The results of clinical and experimental studies are presented. Carbonic anhydrase (CA), E-cadherin, and MUC gene expression were analyzed in patients with LPR, in controls, and in an in vitro model. In patients with LPR, we found decreased levels of CAIII in vocal fold epithelium and increased levels in posterior commissure epithelium. The experimental studies confirm that laryngeal CAIII is depleted in response to reflux. Also, cell damage does occur well above pH 4.0. In addition, E-cadherin (transmembrane cell surface molecules, which have a key function in epithelial cell adhesion) was not present in 37% of the LPR laryngeal specimens. In conclusion, the laryngeal epithelium lacks defenses comparable to those in esophageal epithelium, and these differences may contribute to the increased susceptibility of laryngeal epithelium to reflux-related injury.

Regulatory function of trefoil peptides (TFF) on intestinal cell junctional complexes.

Abstract Trefoil peptides (TFF) are constitutively expressed in the gastrointestinal tract and are involved in gastrointestinal defence and repair by promoting epithelial restitution. Although there is a general consensus regarding the pro-motogenic activity of trefoil peptides, the cellular mechanisms through which they mediate these processes are not completely understood. Pertubation of the E-cadherin/catenin complex at intercellular junctions appears to be a functional pathway through which TFF2 and TFF3 promote cell migration. Tight junction complexes seal the paracellular spaces between cells and contribute to epithelial barrier function. TFF3 peptide stimulation stabilises these junctions through upregulation of the tightening protein claudin-1 and redistribution of ZO-1 from the cytoplasm to the intercellular membrane with an increase in binding to occludin. Modulation of the functional activity and subcellular localisation of epithelial junctional adhesion molecules represent important mechanisms by which trefoil peptides may promote migration of intestinal epithelial cells in vitro and healing of mucosal damage in vivo.

Prevalence of different subtypes of serrated polyps and risk of synchronous advanced colorectal neoplasia in average-risk population undergoing first-time colonoscopy.

OBJECTIVES: A growing body of evidence indicates that patients with sessile serrated adenoma/polyp (SSA/P) and traditional serrated adenoma (TSA) are at risk for subsequent malignancy. Despite increasing knowledge on histological categorization of serrated polyps (SPs) data are lacking on the actual prevalence and the association of each SP subtype with advanced colorectal neoplasia. METHODS: We prospectively determined the prevalence of different SP subtypes and evaluate the association with synchronous advanced neoplasia in asymptomatic average-risk subjects undergoing first-time colonoscopy. All retrieved polyps were examined by two independent pathologists. Serrated lesions were classified into hyperplastic polyps (HP), SSA/P (without and with cytological dysplasia, SSA/P/DIS), and TSA, and were screened for BRAF and K-ras mutations. RESULTS: Among 258 polyps detected in 985 subjects, the proportion of SSA/P and TSA was 8.9% and 1.9% with an overall prevalence of 2.3% and 0.6%, respectively. SSA/Ps were small without significant difference in their location between proximal and distal colon; TSA were predominantly left-sided. BRAF mutation was common in SSA/Ps and K-ras mutation was present in all TSA. Independent predictors of advanced neoplasia were male sex (odds ratio (OR)=2.0, 95% confidence interval (CI) 1.0-4.0), increasing age (OR=4.5, 95% CI 1.5-13.4 for 50-69 years and OR=9.9, 95% CI 3.1-31.5 for >70 years), current smoking (OR=2.0, 95% CI 1.3-6.8), >3 tubular adenoma (OR=3.6, 95% CI 1.9-6.4), and SSA/P (OR=6.0, 95% CI 1.9-19.5). CONCLUSIONS: The substantial prevalence of BRAF-mutated SSA/P and the independent association with synchronous advanced colorectal neoplasia in asymptomatic average-risk subjects support the overall impact of the serrated pathway on colorectal cancer (CRC) risk in general population. The endoscopic characteristics of SSA/P emphasize the need of high-quality colonoscopy as a key factor for an effective CRC screening program.

E-cadherin and the cytoskeletal network in colorectal cancer development and metastasis.

Abnormalities in the expression and functional activity of cell adhesion molecules are implicated in the development and progression of the majority of colorectal cancers (CRC). Cell-cell adhesion molecule E-cadherin regulates cell polarity, differentiation, proliferation and migration through its intimate association to the actin cytoskeletal network. During colorectal carcinogenesis changes in intercellular adhesion and dynamic rearrangements in the actin cytoskeleton result in altered signalling and migration with loss of contact inhibition. The adenomatous polyposis coli (APC) protein, besides its established role in the ß catenin/Wnt signalling pathway, can coordinate microtubule and actin organization during cell migration. The actin-bundling protein Fascin promotes cell motility and is overexpressed in CRC. Based on recent molecular and pathological studies, this review focusses on the role of these molecules sharing the common feature of being associated with the cytoskeletal network during colorectal carcinogenesis and metastasis. The potential use of these molecules as prognostic markers and/or therapeutic targets will also be discussed.

Reduced tumour progression and angiogenesis in 1,2-dimethylhydrazine mice treated with NS-398 is associated with down-regulation of cyclooxygenase-2 and decreased beta-catenin nuclear localisation.

Cyclooxygenase (COX)-2 is a key molecular target of colon cancer prevention. However, the mechanisms by which COX-2 inhibitors confer protective effects against tumour development are not completely understood. The aim of this study was to elucidate the effects of NS-398 in the 1,2-dimethylhydrazine (DMH) mouse model with respect to alteration in the expression of COX-2 and E-cadherin-catenin complex. Alterations in cell proliferation, apoptosis, and vascular density were investigated. NS-398 showed reduced COX-2 immunoreactivity in adenomas with a decrease in vascular density in non-dysplastic mucosa. Adenomas revealed increased E-cadherin and beta-catenin reactivity. NS-398 reduced the percentages of tumour cells with nuclear localisation of beta-catenin and cyclin D1. Bromodeoxyuridine (BrdUrd) index in adenomas was significantly higher in untreated animals. NS-398 resulted in significant increase in apoptosis in adenomas. Our results suggest a protective role of NS-398 on tumour development associated with reduced COX-2 expression, reduced vascular density and perturbation of beta-catenin signalling pathway.

Reduced p120ctn expression correlates with poor survival in patients with adenocarcinoma of the gastroesophageal junction.

BACKGROUND AND OBJECTIVES: P120-catenin (p120ctn) is a member of the E-cadherin-catenin cell-cell adhesion complex. Impairment of one or more of the components of this complex is associated with tumorigenesis. The role of p120ctn in malignancy is not clear yet. We studied the in vivo expression and cellular localization of p120ctn in adenocarcinomas of the gastroesophageal junction. METHODS: Immunohistochemical staining for p120ctn was performed on 96 tumor samples, 20 cases of Barretts metaplasia and 13 lymph node metastases. The relationship with pathological characteristics and patient survival was also assessed. RESULTS: Loss of normal surface p120ctn expression was found in 4/20 (20%) Barretts metaplasia, in 65/96 (68%) tumors, and 11/13 (85%) lymph node metastases. Nuclear immunoreactivity for p120ctn was seen in five tumors. Loss of normal expression of p120ctn was associated with a higher tumor grade (P < 0.0001) but not with pTNM-stage. Reduced expression of p120ctn was correlated with poor survival (P = 0.0002). Cox regression analysis showed that p120ctn is an independent prognostic marker. CONCLUSIONS: Abnormal p120ctn expression is frequently seen in adenocarcinomas of the gastroesophageal junction, and may be a useful as a prognostic marker in these tumors.

Genetics--cellular basis.

Colorectal carcinogenesis is a multistep process during which the specialised epithelial cells of intestinal mucosa surface (e.g. colonocytes) accumulate a series of genetic and epigenetic events which lead to a perturbation of their normal cellular functions and turnover. This review will address the mechanisms and biological effects of these abnormalities on the growth control, differentiation, adhesion and survival of the colonocytes.

Adhesion Molecules as Diagnostic Tools in Tumor Pathology.

Adhesion molecules are transmembrane glycoproteins mediating cell-cell and cell extracellular matrix interactions. They control a number of fundamental biological processes including cell migration, differentiation, proliferation, and apoptosis. In the last decade there has been an increasing interest in the exploitation of these molecules as diagnostic and/or prognostic markers in tumor pathology. For example, a large number of studies have shown that loss of E-cadherin expression correlates with high tumor grade and advanced tumor stage in a number of malignancies. The analysis of adhesion molecule profile in a routine clinical setting needs further investigation in prospective multicenter studies. Int J Surg Pathol 8(3):191-200, 2000

Beta-catenin--a linchpin in colorectal carcinogenesis?

An important role for beta-catenin pathways in colorectal carcinogenesis was first suggested by the protein's association with adenomatous polyposis coli (APC) protein, and by evidence of dysregulation of beta-catenin protein expression at all stages of the adenoma-carcinoma sequence. Recent studies have, however, shown that yet more components of colorectal carcinogenesis are linked to beta-catenin pathways. Pro-oncogenic factors that also release beta-catenin from the adherens complex and/or encourage translocation to the nucleus include ras, epidermal growth factor (EGF), c-erbB-2, PKC-betaII, MUC1, and PPAR-gamma, whereas anti-oncogenic factors that also inhibit nuclear beta-catenin signaling include transforming growth factor (TGF)-beta, retinoic acid, and vitamin D. Association of nuclear beta-catenin with the T cell factor (TCF)/lymphoid enhancer factor (LEF) family of transcription factors promotes the expression of several compounds that have important roles in the development and progression of colorectal carcinoma, namely: c-myc, cyclin D1, gastrin, cyclooxygenase (COX)-2, matrix metalloproteinase (MMP)-7, urokinase-type plasminogen activator receptor (aPAR), CD44 proteins, and P-glycoprotein. Finally, genetic aberrations of several components of the beta-catenin pathways, eg, Frizzled (Frz), AXIN, and TCF-4, may potentially contribute to colorectal carcinogenesis. In discussing the above interactions, this review demonstrates that beta-catenin represents a key molecule in the development of colorectal carcinoma.

Abnormal immunoreactivity of the E-cadherin/catenin (alpha-, beta-, and gamma-) complex in premalignant and malignant non-melanocytic skin tumours.

E-cadherin/catenin (alpha-, beta-, and gamma-) complex plays a critical role in the control of epithelial differentiation. The aim of this study was to examine the immunoreactivity of E-cadherin and alpha-, beta-, and gamma-catenins in premalignant and malignant non-melanocytic skin tumours (NMST) and to correlate their expression with the grade of tumour differentiation, as assessed by the established histopathological criteria and by the Ki-67 index. Benign NMSTs were also studied. To investigate any possible influence of immunosuppression in the expression of E-cadherin and catenins, the study compared tumours obtained from renal transplant recipients (RTRs) and immunocompetent patients. Immunoperoxidase staining of E-cadherin and alpha-, beta-, and gamma-catenins was performed in 42 squamous cell carcinomas (SCCs) (26 from RTRs and 16 from non-RTRs), 30 lesions of Bowen's disease (11 from RTRs and 19 from non-RTRs), 11 atypical squamoproliferative lesions from RTRs, 19 actinic keratoses (9 from RTRs and 10 from non-RTRs), and 20 viral warts from RTRs. The findings of this study were as follows. Firstly, the probability of abnormal expression of E-cadherin and alpha-, beta-, and gamma-catenins increased from benign to premalignant and malignant NMSTs (p<0.001 for all). Secondly, there was agreement in abnormal expression between most of the molecules measured in malignant and premalignant NMSTs (p<0.05). Thirdly, in SCC, abnormal expression of E-cadherin and catenins was more frequent in lesions with a high (>40%) Ki-67 index than in those with a low Ki-67 index (<40%) (p=0.003). However, only the abnormal expression of gamma-catenin increased with the grade of SCC differentiation (p=0.008). Fourthly, abnormal expression of gamma-catenin predicted a high proliferation index (Ki-67 index 40%) in NMSTs (p<0.01, OR=6.19). Finally, there was no difference in the abnormal expression of E-cadherin and catenins between NMSTs from immunosuppressed and immunocompetent patients. Thus, abnormal expression of the E-cadherin/catenin complex was quite common in SCC and Bowen's disease and also in a proportion of intraepithelial dysplastic lesions, such as atypical squamoproliferative lesions and actinic keratosis, suggesting that these changes may be early indicators of the neoplastic process. Abnormal expression of gamma-catenin was the sole predictor of high proliferation in NMST and was also correlated with the tumour grade, suggesting a possible important role for gamma-catenin in tumourigenesis.

Abnormalities of the cadherin-catenin complex in chemically-induced colo-rectal carcinogenesis.

Beta-Catenin is a multifunctional protein originally identified as a component of the cadherin cell-cell adhesion complex. It also binds the adenomatous polyposis coli (APC) tumour suppressor which controls beta-catenin cellular levels through its degradation. (beta-Catenin and/or APC mutations result in increased cytoplasmic Beta-catenin and nuclear translocation. The aim of the present study was to examine the expression and cellular localisation of alpha and beta-catenin, p120 and E-cadherin in a chemically-induced mouse model of colo-rectal cancer using 1,2-dimethylhydrazine (DMH). Female Balb/C mice were injected subcutaneously with a solution providing 25 mg DMH base/kg body weight for 17 weeks. Animals were killed and tumours identified in the intestine with a dissecting microscope. Formalin-fixed paraffin-embedded sections of normal and dysplastic colonic mucosa were stained by an indirect avidin-biotin immunohistochemical technique using mouse monoclonal antibodies, and membranous, cytoplasmic and nuclear cellular localisation was assessed by light microscopy. Staining distribution scored as follows: 3, > 90 % positive epithelial cells; 2, >50 % positive epithelial cells; 1, <50 % positive epithelial cells. Non-dysplastic colonic epithelial cells revealed beta-catenin expression at the membrane (33/41 scored 3),areas of cytoplasmic expression (24/41 scored 1) and no nuclear staining. Dysplastic colonic epithelium revealed increased membranous and cytoplasmic, beta-catenin immunoreactivity (39/41 and 38/41 both scored 3) with focal nuclear staining (14/41). Expression patterns for ac-catenin, p120, and E-cadherin were similar to beta-catenin with increased membranous and cytoplasmic immunoreactivity in dysplastic mucosa, although no nuclear staining was observed. Increased cytoplasmic expression and nuclear localisation of beta-catenin are consistent with a possible mutation in its gene, and this finding was in keeping with the mutational analysis of exon 3 by single-strand conformational polymorphism. Increased immunoreactivity of the other catenins also suggests further disruption in catenin regulation. In summary, alterations in the beta-catenin expression and cellular localisation in the DMH-induced tumours are similar to those seen inhuman sporadic colorectal tumours. The DMH is therefore a useful model for studying the abnormalities of the E-cadherin-catenin pathway in colorectal carcinogenesis.