Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0001430 (adenoma)
 21,222 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cadherin is an Ca2+ dependent adhesion molecules, which contribute to cell-cell adhesion and maintenance of tissue structures. Its decrease or functional abnormality plays an important vole in cancer invasion and metastasis. We investigate the expression of E- cadherin in thyroid neoplasms (papillary cancer, follicular cancer, medullary cancer anaplastic cancer and follicular adenoma) and normal thyroid. The decrease of E-cadherin expression in thyroid cancer correlates with its malignancy and metastatic potentiality.
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PMID:[Expression of E-cadherin in thyroid neoplastic tissues and its correlation with malignant and metastatic potential]. 762 98

Gastric cancer involves changes in multiple oncogenes and multiple suppressor genes, and it causes genetic instability. Aberrant expression and amplification of the c-met gene, inactivation of the p53 gene, and CD44 abnormal transcripts are common events of both well differentiated and poorly differentiated gastric cancers. Amplification of the cyclin E gene is also observed in gastric cancer regardless of histologic type. Decreased expression of the pic1 (p21) gene occurs independent of the p53 mutations. In addition, K-ras mutations, c-erbB-2 gene amplification, loss of heterozygosity (LOH) and mutations of the APC gene, LOH of the bcl-2 gene, and LOH at the DCC locus are preferentially associated with well differentiated gastric cancer. Moreover, LOH on chromosome 1q is involved in the progression of well differentiated cancer. Precancerous lesions, including hyperplastic polyp, intestinal metaplasia, and adenoma, share genetic changes found in well differentiated cancers. Conversely, genetic instability may be involved in the first step of stomach carcinogenesis of the poorly differentiated type. Reduction or loss of cadherin and catenins, K-sam gene amplification, and c-met gene amplification are necessary for the development and progression of poorly differentiated or scirrhous carcinoma. Interaction between cell-adhesion molecules in the c-met expressed tumor cells and hepatocyte growth factor from stromal cells is implicated in the morphogenesis of two types of gastric cancer.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Molecular biology of gastric cancer. 767 88

Gene changes in multiple oncogenes, multiple growth factors and multiple tumor-suppressor genes are observed in stomach cancer. Among them, those most commonly implicated in both well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma are inactivation (mutations and allele loss) of the p53 gene, and activation (abnormal expression and amplification) of the c-met gene. Moreover, they occur at an early stage of stomach carcinogenesis. In addition, loss of heterozygosity (LOH) on chromosome 5q (APC locus) is frequently associated with well-differentiated adenocarcinoma. LOH on chromosome 18q (DCC locus) and LOH of the bcl-2 gene also are common events of well-differentiated adenocarcinoma. LOH on chromosomes 1q and 7q may be involved in the progression of well-differentiated adenocarcinoma. Conversely, the development of poorly differentiated adenocarcinoma, in addition to changes in p53 and c-met genes, requires reduction or dysfunction of cadherin. Overexpression of bcl-2 protein is observed in poorly differentiated adenocarcinoma or signet-ring cell carcinoma. Moreover, the K-sam gene is amplified preferentially in poorly differentiated adenocarcinoma of scirrhous carcinoma. K-sam amplification in scirrhous carcinoma often occurs independently of c-met gene amplification. LOH on chromosome 1p also is relatively common in poorly differentiated adenocarcinoma. Exceptionally, signet-ring cell carcinoma shares APC mutations. There are some differences in expression of the growth-factor/receptor system between well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma. Moreover, interaction between cell-adhesion molecules in tumor cells expressing c-met and hepatocyte growth factor (HGF) from stromal cells is linked with morphogenesis of two histological types of stomach cancer. Intestinal metaplasia and adenoma of the stomach also contain p53 mutations and K-ras mutations or tpr-met rearrangement. Taken together, different genetic pathways of stomach carcinogenesis may exist for poorly differentiated and well-differentiated stomach cancers. Some of the latter may develop by a cumulative series of gene alterations similar to those of colorectal cancer.
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PMID:Molecular mechanism of stomach carcinogenesis. 844 Jul 43

It has been found that beta-catenin, a key regulator of the cadherin-mediated cell adhesion system, forms complexes with adenomatous polyposis coli (APC) tumor suppressor protein, and beta-catenin expression levels are affected by exogenously induced APC protein. The effects of intrinsic APC protein alteration on beta-catenin expression levels and its subcellular localization were examined in colonic epithelia of eight patients with familial adenomatous polyposis. In all eight patients, beta-catenin was immunostained at the membranes of the cell-to-cell borders in normal epithelial cells, whereas the nuclei and cytoplasms stained intensely in addition to the membranes in both adenoma and cancer cells. beta-Catenin expression levels in tumor tissues were over three times higher than those in corresponding normal mucosae of all of the three patients, whose resected specimens were available for quantitative immunoblot analysis. In these three patients, mutant truncated APC proteins were detected and shown to have lost the central region, including a known beta-catenin binding domain. beta-Catenin was not coimmunoprecipitated with these mutant APC proteins in tumor tissues but was able to be coprecipitated with glutathione S-transferase-fused APC protein containing a beta-catenin binding domain. These results suggest that the absence of wild type APC protein affects the subcellular localization and expression levels of beta-catenin in human tissues.
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PMID:Alteration of beta-catenin expression in colonic epithelial cells of familial adenomatous polyposis patients. 861 74

The scenario of multistep of stomach carcinogenesis differs depending on the two histological types, well differentiated adenocarcinoma and poorly differentiated adenocarcinoma, because the two types may have different genetic pathways. Genetic instability, reactivation of telomerase and abnormal transcript of CD44 including intron 9 are common events of both well and poorly differentiated type carcinomas. These occur at early stage of carcinogenesis, even in precancerous lesions such as intestinal metaplasia and adenoma. Inactivation of APC, activation of K-ras, amplification of c-erbB2, and allelic loss of DCC locus are associated with well differentiated type, while amplification of K-sam and functional loss of cadherin/catenin are characteristics of poorly differentiated type. HGF/c-met system plays a pivotal role in morphogenesis of both histological types through interaction with cell-cell adhesion molecules. Reactivation of telomerase or genetic instability may be an initial event for accumulation of multiple genetic alterations during the progression of stomach carcinogenesis.
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PMID:[Genetic alterations in stomach cancer]. 869 39

Epithelial properties of thyrocytes are difficult to maintain in conventional cell culture systems. We used bicameral chambers (Transwell) in attempts to establish a functional epithelium of thyrocytes of human origin. Thyroid follicle segments were isolated by collagenase digestion of paradenomatous tissue obtained at surgery for follicular adenoma and of tissue from glands with Graves' disease. After careful separation from connective tissue and single cells by centrifugation, the follicles were plated at high density on the collagen-coated filter of the chambers and cultured in Eagle's essential medium (EMEM) containing 10% fetal calf serum (FCS) or Coon's modified Hams medium enriched with five or six factors (5H, 6H); the latter media contained 5% FCS without (5H) or with (6H) thyrotropin (TSH). The follicles were converted into a confluent cell layer, which had similar DNA content irrespective of type of medium, after 4-6 days. Cells grown in EMEM or 5H established a transepithelial electrical resistance (R) of 200-500 omega.cm2 and was impermeable to [3H]inulin, indicating the formation of epithelial junctions. Addition of 6H to confluent cells initially cultured in EMEM or 5H caused a further increase of R, maximally to 1500 omega.cm2, along with a rise of the transepithelial potential difference; 6H promoted the monolayer formation of cells, increased the number of apical microvilli and reinforced the junctional distribution of actin, cadherin and ZO-1; 6H also enhanced the polarized secretion of [3H]leucine-labeled thyroglobulin into the apical medium. Cells from Graves' thyroid tissue established an epithelium on the filter with similar characteristics to that of normal thyrocytes; some platings contained in addition large numbers of HLA-DR positive cells with a dendritic shape. HLA-DR expression was generally absent in EMEM-or 5H-grown thyrocytes, but appeared in limited areas of the cell layer after 6H and was expressed by all epithelial cells after interferon-gamma stimulation for 48 h. We conclude that human thyrocytes form a tight and polarized epithelium when cultured on permeable filters. The polarized structure and function of the cells are positively regulated by TSH. The culture system may be useful in studies addressing the role of the epithelial phenotype (cell polarity and tight barrier) in normal thyroid function as well as in pathological processes in the thyroid, such as autoimmunity, cell transformation and tumor progression.
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PMID:Primary culture of human thyrocytes in Transwell bicameral chamber: thyrotropin promotes polarization and epithelial barrier function. 892 31

Little is known about the the signalling pathways driving the adenoma-to-carcinoma sequence in human colonic epithelial cells. Accumulation and activation of the src tyrosine kinase in colon cancer suggest a potential role of this oncogene in this early progression. Therefore, we introduced either activated src (m-src), polyoma-MT alone or combined with normal c-src in the adenoma PC/AA/C1 cell line (PC) to define the function and phenotypic transformations induced by these oncogenes in familial adenomatous polyposis (FAP) colonic epithelial cells. Functional expression of these oncoproteins induced the adenoma-to-carcinoma conversion, overexpression of the hepatocyte growth factor (HGF) receptor Met, but failed to confer invasiveness in vivo and in vitro, or to produce alterations in cell proliferation and differentiation. In contrast, PC-msrc cells became susceptible to the HGF-induced invasion of collagen gels and exhibited sustained activation of the pp60src tyrosine kinase and Tyr phosphorylation of the 120-kDa E-cadherin, which was further increased by HGF Transcripts of HGF were clearly identified by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot in the parental and transformed PC cells, suggesting an autocrine mechanism. Taken together, the data indicate that: (1) experimental activation of src and PyMT pathways directly induces tumorigenicity and Met upregulation in a colon adenoma cell line; (2) HGF-activated Met and src cooperate in inducing invasion; (3) in view of the molecular associations between catenins and cadherin or the tumour-suppressor gene product APC, the cell adhesion molecule E-cadherin may constitute a downstream effector of src and Met.
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PMID:Progression of familial adenomatous polyposis (FAP) colonic cells after transfer of the src or polyoma middle T oncogenes: cooperation between src and HGF/Met in invasion. 901 33

beta-Catenin has a central role not only in linking the cadherin-mediated cell adhesion system but also in the intercellular signalling pathway. To investigate alterations of beta-catenin in the development of colorectal carcinoma, the pattern of beta-catenin expression was studied using immunohistochemistry in 74 sporadic colorectal adenomas, in histologically normal mucosa adjacent to 65 of these adenomas, and in 52 carcinomas arising in adenomas. All normal epithelia displayed cell boundary staining for beta-catenin. Adenomas and carcinomas showed varying degrees of membranous staining. However, some tumours also showed nuclear staining of beta-catenin protein. Decreased membranous and increased nuclear beta-catenin staining were associated with increasing degrees of dysplasia in adenomas (P < 0.005, P < 0.05, respectively). Carcinomas manifested significantly reduced membranous, but enhanced nuclear beta-catenin expression compared with their associated adenomas (P < 0.001, P < 0.005, respectively). An inverse correlation was found between decreased membranous and increased nuclear staining of beta-catenin in both adenomas and carcinomas (P < 0.025, P < 0.05, respectively). The data confirm that reduced membranous and increased nuclear expression of beta-catenin is associated with the progression of colorectal adenomas to carcinomas. Our results also suggest that decreased membranous expression of beta-catenin may result from aberrant localisation of the protein in the cell nucleus.
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PMID:Reciprocity between membranous and nuclear expression of beta-catenin in colorectal tumours. 933 37

Beta-Catenin is a key regulator of the cadherin-mediated cell-cell adhesion system and an important element in the Wnt signal transduction pathway. Stabilization and accumulation of cytoplasmic beta-catenin, which result from mutations in either the adenomatous polyposis coli or beta-catenin genes, are causatively associated with colon carcinogenesis. In the present study, we examined the expression of beta-catenin in rat colon tumors induced by azoxymethane in comparison with adjacent normal colon mucosa by immunostaining and immunoblotting. Cytoplasmic and nuclear immunostaining was pronounced in all colon adenoma and carcinoma tissues, whereas antibody binding was limited to membranes at the intercellular borders in normal colon epithelial cells. Increase of the free beta-catenin fraction in tumor cells was also indicated by immunoblot analysis of fractionated tissue lysates. Investigation of mutations in the glycogen synthase kinase-3beta phosphorylation consensus motif of the beta-catenin gene by PCR-single strand conformation polymorphism methods and direct sequencing revealed eight mutations in six of the eight colon carcinomas, and seven of these were shown to be G:C to A:T transitions, with five being CTGGA to CTGAA. Such frequent mutations of the beta-catenin gene in azoxymethane-induced rat colon tumors suggest that consequent alterations in the stability and localization of the protein may play an important role in this colon carcinogenesis model.
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PMID:Beta-catenin is frequently mutated and demonstrates altered cellular location in azoxymethane-induced rat colon tumors. 942 55

Development of malignant tumours is in part characterized by the ability of a tumour cell to overcome cell-cell adhesion and to invade surrounding tissue. E-cadherin is the main adhesion molecule of epithelia, and it has been implicated in carcinogenesis because it is frequently lost in human epithelial cancers. Re-establishing the functional cadherin complex in tumour cell lines results in a reversion from an invasive to a benign epithelial phenotype. However, it remained unresolved whether the loss of E-cadherin-mediated cell adhesion was a cause or a consequence of tumour progression in vivo. Here we report that the loss of E-cadherin expression coincides with the transition from well differentiated adenoma to invasive carcinoma in a transgenic mouse model of pancreatic beta-cell carcinogenesis (Rip1Tag2). Intercrossing Rip1Tag2 mice with transgenic mice that maintain E-cadherin expression in beta-tumour cells results in arrest of tumour development at the adenoma stage, whereas expression of a dominant-negative form of E-cadherin induces early invasion and metastasis. The results demonstrate that loss of E-cadherin-mediated cell adhesion is one rate-limiting step in the progression from adenoma to carcinoma.
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PMID:A causal role for E-cadherin in the transition from adenoma to carcinoma. 951 65


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