Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Smad4 is a tumour suppressor gene predominantly involved in gastrointestinal carcinogenesis. Loss of Smad4 is considered to be a genetically late step and occurs in up to 30% of metastatic colorectal carcinomas. Smad4, originally characterized as an intracellular transmitter of transforming growth factor-beta (TGF-beta) signals, is a transcriptional co-modulator capable of integrating cellular responses to multiple signalling cascades. Thus, there are many Smad4 target genes and they are presumably strongly context-dependent. It was recently shown that re-expression of Smad4 in Smad4-deficient SW480 human colon carcinoma cells restored epithelioid morphology and induced P-cadherin and E-cadherin transcription. The cadherins are key players in cell-cell adhesion connecting adjacent cells via the cadherin-catenin adhesion complex. Frequent loss of E-cadherin expression in human cancers has been a long-standing observation, but the underlying mechanisms are not yet fully understood. To assess the role of Smad4 in E-cadherin regulation in colorectal carcinogenesis further, the present study has analysed Smad4 and E-cadherin RNA and protein expression in colorectal carcinoma cell lines and in 51 late-stage colorectal carcinomas. In primary tumours, loss of Smad4 expression correlated highly significantly with loss of E-cadherin expression, thus providing further evidence for involvement of the tumour suppressor Smad4 in the control of expression of the tumour and invasion suppressor E-cadherin.
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PMID:Loss of Smad4 correlates with loss of the invasion suppressor E-cadherin in advanced colorectal carcinomas. 1509 68

The cadherin superfamily of Ca(2+)-dependent homophilic adhesion molecules plays a critical role in regulating cell-to-cell interactions. During development, the expression of different cadherins is highly dynamic, since they are associated with the morphogenesis, establishment and/or maintenance of different tissues. Alterations in cadherin expression or function occur frequently during carcinogenesis, such as the loss of the epithelial cadherin (E-cadherin) and/or the aberrant expression of other cadherins. Indeed, the aberrant expression of cadherins has been detected during carcinoma invasion, a process which is reminiscent of the epithelial-mesenchymal transition (EMT) so important in many critical developmental processes. The functional regulation of cadherins can occur at many different levels, from transcriptional regulation to the control of the strength of the cadherin-mediated cell-cell interaction. In this review, we will focus on the transcriptional control of cadherin expression, both in development and carcinogenesis, paying particular attention to the regulation of E-cadherin given its proposed role as a suppressor of invasion. We will discuss the main genetic and epigenetic mechanisms involved in down-regulating E-cadherin expression, and we will analyse the mechanisms involved in regulating EMT, in an attempt to elucidate which elements are common to this process in both physiological and pathological situations.
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PMID:Transcriptional regulation of cadherins during development and carcinogenesis. 1534 12

Desmosomal adhesion is important for the integrity and protective barrier function of the epidermis and is disregulated during carcinogenesis. Strong adhesion between keratinocytes is conferred by the desmosomal cadherins, desmocollin (Dsc) and desmoglein. These constitute two gene families, members of which are differentially expressed in epidermal strata. It has been suggested that this stratum-specific expression regulates keratinocyte differentiation. We tested this hypothesis by misdirecting the expression of the basally abundant desmosomal cadherins Dsc3a and Dsc3b to suprabasal differentiating keratinocytes in transgenic mice. No phenotype was apparent until adulthood, when mice developed variable ventral alopecia and had altered keratinocyte differentiation within affected areas. The follicular changes were reminiscent of changes in transgenic mice with an altered beta-catenin stability. Stabilized beta-catenin and increased beta-catenin transcriptional activity were demonstrated in transgenic mice prior to the phenotypic change and in transgenic keratinocytes as a consequence of transgene expression. Hence, a link between desmosomal cadherins and beta-catenin stability and signaling was demonstrated, and it was shown that desmocollin cadherin expression can affect keratinocyte differentiation. Furthermore, the first function for a "b-type" desmocollin cadherin was demonstrated.
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PMID:Desmosomal cadherin misexpression alters beta-catenin stability and epidermal differentiation. 1565 25

P-Cadherin/CDH3 belongs to the family of classic cadherins that are engaged in various cellular activities including motility, invasion, and signaling of tumor cells, in addition to cell adhesion. However, the biological roles of P-cadherin itself are not fully characterized. Based on information derived from a previous genome-wide cDNA microarray analysis of microdissected pancreatic ductal adenocarcinoma (PDAC), we focused on P-cadherin as one of the genes most strongly overexpressed in the great majority of PDACs. To investigate the consequences of overexpression of P-cadherin in terms of pancreatic carcinogenesis and tumor progression, we used a P-cadherin-deficient PDAC cell line, Panc-1, to construct a cell line (Panc1-CDH3) that stably overexpressed P-cadherin. Induction of P-cadherin in Panc1-CDH3 increased the motility of the cancer cells, but a blocking antibody against P-cadherin suppressed the motility in vitro. Overexpression of P-cadherin was strongly associated with cytoplasmic accumulation of one of the catenins, p120ctn, and cadherin switching in PDAC cells. Moreover, P-cadherin-dependent activation of cell motility was associated with activation of Rho GTPases, Rac1 and Cdc42, through accumulation of p120ctn in cytoplasm and cadherin switching. These findings suggest that overexpression of P-cadherin is likely to be related to the biological aggressiveness of PDACs; blocking of P-cadherin activity or its associated signaling could be a novel therapeutic approach for treatment of aggressive pancreatic cancers.
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PMID:Overexpressed P-cadherin/CDH3 promotes motility of pancreatic cancer cells by interacting with p120ctn and activating rho-family GTPases. 1583 38

Inactivation of the cadherin-mediated cell-cell adhesion system is believed to play a role in the initial steps of cancer invasion and metastasis. Expression of E-cadherin and its intracytoplasmic binding molecules (alpha-catenin, beta-catenin, and plakoglobin) was examined immunohistochemically in 84 cases of intrabronchial precancerous lesions (bronchial squamous metaplasia (BSM) without atypia, BSM with atypia, dysplasia), and 21 cases of carcinoma in situ, and 4 cases of microinvasion to the bronchial wall, and 32 cases of stage I well differentiated squamous cell carcinoma (squamous cell carcinoma) to investigate the association between expression of E-cadherin and/or catenins and cancer progression. Reduced expression of E-cadherin and/or catenins was closely correlated with an atypical grade of dysplasia in the basal layer (p<0.05). In particular, downregulation of E-cadherin and/or catenins was associated with an atypical grade of BSM with atypia in intrabronchial lesions (p<0.01). We conclude that downregulation of alpha-catenin and/or beta-catenin, which may reflect dysfunction of the cadherin-mediated cell-cell adhesion system, is an important marker for atypical grade during carcinogenesis of the bronchial epithelium.
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PMID:Frequent loss of E-cadherin and/or catenins in intrabronchial lesions during carcinogenesis of the bronchial epithelium. 1589

Plakoglobin (gamma-catenin) and beta-catenin are pivotal components of cell-cell adherent junctions that link cadherin receptors to the actin cytoskeleton. Whereas beta-catenin overexpression induces cell proliferation and tumor formation, plakoglobin induces tumor suppressor activity. We investigated the expression of plakoglobin in alveolar (ARMS) and embryonal (ERMS) rhabdomyosarcoma (RMS) cell lines and tumors, and found that plakoglobin is present both in the cytoplasm and in the nucleus of ERMS cells, whereas it is absent or detectable at extremely low levels in ARMS. As gene silencing can be mediated by methylation and/or deacetylation of promoter regions, we assessed the effects of the DNA demethylating agent 5-Aza-2'-deoxycytidine (5AzadC) and of the histone deacetylase inhibitor Trichostatin A (TSA), and obtained restoration of plakoglobin expression in ARMS cells cultivated in the presence of 5AzadC and TSA. By methylation-specific PCR, ARMS cells were shown to contain methylated CpG dinucleotides in CpG islands located around the transcriptional start site of one or both alleles, whereas ERMS cells did not. Furthermore, we demonstrated that promoter regions (P1-P3) of plakoglobin gene were associated with hypoacetylated H4 histone in ARMS cells RH4, suggesting that aberrant DNA methylation of the 5' CpG island and histone deacetylation play key roles in silencing the plakoglobin gene. These results demonstrate that plakoglobin is differentially expressed in ARMS and ERMS and that its expression depends on the methylation and acetylation status of the gene.
Carcinogenesis 2006 Sep
PMID:Plakoglobin is differentially expressed in alveolar and embryonal rhabdomyosarcoma and is regulated by DNA methylation and histone acetylation. 1653 59

Protocadherins are a major subfamily of the cadherin superfamily, but little is known about their functions and intracellular signal transduction. We identified a homozygous loss of protocadherin 20 (PCDH20, 13q21.2) in the course of a program to screen a panel of non-small-cell lung cancer (NSCLC) cell lines (1 of 20 lines) for genomic copy number aberrations using an in-house array-based comparative genomic hybridization. PCDH20 mRNA was expressed in normal lung tissue but was not expressed in the majority of NSCLC cell lines without a homozygous deletion of this gene (10 of 19 lines, 52.6%). Expression of PCDH20 mRNA was restored in gene-silenced NSCLC cells after treatment with 5-aza 2'-deoxycytidine. The DNA methylation status of the PCDH20 CpG-rich region correlated inversely with the expression of the gene and a putative target region for methylation showed clear promoter activity in vitro. Methylation of this PCDH20 promoter was frequently observed in primary NSCLC tissues (32 of 59 tumors, 54.2%). Among our primary NSCLC cases, the methylated PCDH20 seemed to be associated with a shorter overall survival (P = 0.0140 and 0.0211 in all and stage I tumors, respectively; log-rank test), and a multivariate analysis showed that the PCDH20 methylation status was an independent prognosticator. Moreover, restoration of PCDH20 expression in NSCLC cells reduced cell numbers in colony formation and anchorage-independent assays. These results suggest that epigenetic silencing by hypermethylation of the CpG-rich promoter region of PCDH20 leads to loss of PCDH20 function, which may be a factor in the carcinogenesis of NSCLC.
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PMID:Frequent silencing of the candidate tumor suppressor PCDH20 by epigenetic mechanism in non-small-cell lung cancers. 1665 12

The Tiam1 gene encodes a guanine nucleotide exchange factor (GEF) that specifically activates the Rho-like GTPase Rac. In vitro studies indicate that Tiam1 localizes to adherens junctions and plays a role in the formation and maintenance of cadherin-based cell adhesions, thereby regulating migration of epithelial cells. In vivo studies implicate Tiam1 in various aspects of tumorigenesis. In this chapter, we discuss the use of the DMBA/TPA chemical carcinogenesis protocol in Tiam1-deficient mice to study the role of Tiam1 in Ras-induced skin tumors. This two-stage carcinogenesis protocol allows us to study initiation, promotion, and progression of tumors in a Tiam1-positive and Tiam1-negative background. Moreover, we describe methods to study the role of Tiam1 in susceptibility to apoptosis, cell growth, and Ras transformation by in vivo and in vitro experiments. The latter makes use of tumor cells and primary embryonic fibroblasts and keratinocytes isolated from mice.
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PMID:The Rac activator Tiam1 and Ras-induced oncogenesis. 1675 31

E- cadherin is a member of the cadherin superfamily known as the main mediator of the cell- cell calcium dependent adhesion interactions. Research evidence also yields to this adhesion molecule an important role in carcinogenesis and tumor progression. This review focuses on the differential expression of E- cadherin in the various anatomic sites of the human body where HNSCC arises. Controversies in the results of various studies are discussed and possible prospects for application of all this developing knowledge to prognosis and therapy of the disease are briefly mentioned.
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PMID:Role and expression patterns of E-cadherin in head and neck squamous cell carcinoma (HNSCC). 1676 12

Anti-proliferative properties of genistein in prostate and other cancers have been studied extensively. However, the identification of genistein targets that may mediate its chemopreventive effects in vivo requires further elucidation. In this study, we have demonstrated that the incorporation of genistein in the diet of transgenic adenocarcinoma mouse prostate model (TRAMP/FVB) mice resulted in a reduction in prostate size and the incidence of poorly differentiated (PD) cancer ensuing in an accumulation of prostates at the prostatic intra-epithelial neoplasia (PIN) stage. TRAMP/FVB prostate cancer progression and the onset of PD cancer were characterized by the activation of acutely transforming retrovirus AKT8 in rodent T cell lymphoma (Akt), phosphorylation of glycogen synthase kinase 3-beta (GSK-3beta), post-transcriptional up-regulation of cyclin D1 and repression of cadherin-1 via snail-1 up-regulation. Incorporation of genistein in the diet significantly inhibited the activation of Akt, restored the activation of GSK-3beta, reduced cyclin D1 levels post-transcriptionally and maintained the expression of the cadherin-1 complex via down-regulation of snail-1. By identifying the Akt-GSK-3 pathway and subsequently its downstream effectors, as targets for genistein chemopreventive action, we have elucidated one possible mechanism by which genistein decreases the proliferative potential, retards cancer progression and maintains the integrity of the prostatic epithelial cells in vivo.
Carcinogenesis 2007 Aug
PMID:Akt GSK-3 pathway as a target in genistein-induced inhibition of TRAMP prostate cancer progression toward a poorly differentiated phenotype. 1746 12


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