Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interpretation of cancer as a somatic evolutionary process involving genetic mutation followed by selection, traces its origins to the early years this century. The dramatic developments in molecular genetics have substantiated these early ideas. Through the application of positional cloning and genomic analysis, many mutations in particular genes, both dominant oncogenes and tumour suppressor genes have now been found in a wide variety of tumours. Other genetic events such as non-disjunction leading to haploid expression of a gene and so reduced gene dosage, or epigenetic changes following, for example, changes in methylation patterns leading to reduced or increased gene expression, may also play critical roles in the progression of a cancer. The analysis of mutations at different stages of colorectal cancer provides a good model for following the initiation and progression of a cancer. Mutations in the APC gene, which explain familial adenomatous polyposis, occur in a high proportion of sporadic colorectal carcinomas and appear to be the earliest known changes. Patterns of mutation in the gene suggest dominant negative or gain of function effects, and also reveal important low penetrance subpolymorphic missense mutations that nevertheless may have a very significant impact on the genetic contribution to colorectal cancer susceptibility. Mutations are also found in related genes in the APC pathway, such as beta-catenin and E-cadherin. Mutations in mismatch repair genes (hMLH1 and hMSH2) have also been shown to occur, as well as reduced expression due to methylation changes, in 10% to 20% of sporadic colorectal carcinomas. In addition, mutations in the well known oncogenes p53 and ras are commonly found. The growth of a cancer is a balance between the rate of cell division and the rate of cell death or apoptosis. Thus, genetic changes which reduce the probability of apoptosis, such as p53 and probably hMLH1, are as important a feature of the evolution of a cancer as those which enhance the independence (APC) and rate of cell division (growth factors). Simple models for the evolution of a cancer that take into account these two processes, show that cancers evolve initially by a series of finite increases in cell population size, following which there may be long periods of cell turnover during which there is an opportunity for further mutation and selection. This explains the long lag periods between the initiation and subsequent progression of most cancers. Our rapidly developing understanding of cancers at the fundamental genetic level provides new opportunities for developing targeted treatments, as well as novel approaches to prevention and early detection.
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PMID:1998 Runme Shaw Memorial Lecture: somatic evolution of cancer. 1057 14

The objectives of this study were to: (a) characterize the immunohistochemical expression of p53, bcl-2, E-cadherin (EC), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinases-1 (TIMP-1) in brain metastases; (b) compare immunohistochemical (IHC) expression of brain metastases with their primary tumors; and (c) assess the prognostic value of expression of these markers. Tumors from 35 patients with brain metastasis were studied for IHC expression of p53, bcl-2, EC, MMP-9, and TIMP-1. In 17 cases, primary tumors were also available for study. In brain metastases, p53 was positive in 91% of cases and intermediate in 9%, MMP-9 was positive in all cases, TIMP-1 was intermediate in 6% and negative in 94% of cases, EC expression was positive in 86% of cases and intermediate in 14%, and bcl-2 was variable. All primary tumors were positive for p53 and MMP-9, 3% were intermediate for TIMP-1 and 97% were negative, 65% were positive for EC and 35% were intermediate, whereas bcl-2 expression was variable. Neither p53, bcl-2, TIMP-1, or EC staining correlated with overall survival or survival with brain metastases. No assessment of survival differences could be made for MMP-9 because of its overexpression in all tissues. This study found that MMP-9 and p53 were markedly overexpressed in primary tumors and matched brain metastasis, TIMP-1 expression was negative in the majority of specimens, whereas EC expression was maintained in both primary tumors and brain metastases and bcl-2 expression was variable. This study suggests that the functional balance of MMP-9 and TIMP-1 is shifted toward extracellular matrix degradation in brain metastases and that deregulation of cell cycle control by p53 also exists in brain metastases. The high expression of EC may indicate the importance of adherence at late stages of metastasis but requires further study.
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PMID:Expression of p53, bcl-2, E-cadherin, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 in paired primary tumors and brain metastasis. 1063 35

Tumour cell invasion and metastasis are the processes which kill most cancer patients. Tumour cells with the greatest invasive and metastatic capacity may be those with the highest number of genetic aberrations. The present study has analysed the expression of several tumour-related proteins in both primary tumours and metastatic lesions from 34 breast cancer patients. Protein expression of p53, bcl-2, p21, cyclin D1, E-cadherin, alpha-catenin, beta-catenin, and gamma-catenin was investigated by immunohistochemistry (IHC) using monoclonal antibodies. Metastatic tissue showed a different expression profile from the primary tumour in most patients. The most significant finding was the re-expression of E-cadherin, alpha-catenin, and beta-catenin, and increased down-regulation of gamma-catenin, in metastatic lesions. These results demonstrate that tumour cells, when released from the primary site and after regrowth elsewhere, are capable of re-expression of adhesion molecules. gamma-catenin may play a different role in metastatic lesions than in primary tumours, since it is selectively down-regulated in tumour tissue at the metastatic site.
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PMID:Re-expression of E-cadherin, alpha-catenin and beta-catenin, but not of gamma-catenin, in metastatic tissue from breast cancer patients [seecomments]. 1064 Sep 85

The cyclin-dependent kinase inhibitor p21WAF1 has been characterized as an important effector of the tumor suppressor p53 and has been linked to various growth-regulatory processes. To identify a potential role of p21 in anchorage-dependent growth control, we analyzed a pair of HCT116 human colon carcinoma cell lines that differed only in their p21 status. We found that during suspension culture, HCT116 cells (which contain wildtype p53 and p21) continued to proliferate and formed compact multicellular spheroids (MCSs). In contrast, HCT116 cells engineered to lack functional p21 (HCTp21-/-) were unable to form MCSs in suspension culture, ceased proliferation, and eventually died through apoptosis. The parental HCT116 cells underwent the same fate when treated with hyaluronidase, indicating that cell-cell contact might be required for survival in suspension culture. We established that E-cadherin was induced in HCT116 but not in HCTp21-/- cells and accounted for the formation of MCSs. Forced expression of E-cadherin or p21 in HCTp21-/- cells restored the ability to form MCSs and to grow independently of anchorage. Moreover, HCTp21-/- cells exhibited a severely reduced transformed phenotype and demonstrated greatly enhanced chemosensitivity in suspension culture. Thus, our results link an important regulator of the cell cycle machinery to the expression of a cell-cell adhesion molecule involved in tumor formation. Because our results indicate that loss of p21 severely impairs the ability of HCT cells to grow independently of anchorage, it may not be coincidental that inactivating mutations of this gene are very rarely found in tumor cells.
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PMID:p21WAF1 regulates anchorage-independent growth of HCT116 colon carcinoma cells via E-cadherin expression. 1064 68

The apoptosis-resistant phenotype of cloned high-metastatic A11 and low-metastatic P29 cells isolated from Lewis lung carcinoma was compared. The results showed that A11 cells were more resistant to apoptosis induced by microenvironmental stresses such as serum starvation, glucose deprivation and hypoxia than P29 cells as judged by viability, DNA laddering, and chromatin condensation and fragmentation. Both cell lines were insensitive to tumor necrosis factor-alpha-mediated apoptosis. P29 cells expressed a much higher level of Fas antigen on the cell surface than A11 cells. However, both cell lines were also insensitive to Fas-mediated apoptosis. The apoptosis resistant phenotype of A11 cells was associated with the expression level of caspase-3, but not with those of Bcl-2, Bcl-X(L) Bax, p27Kip1 and DAP kinase. There was no difference between A11 and P29 cells in the expression of E-cadherin, the adhesiveness to the extracellular matrix components or the expression levels of metastasis-associated genes such as c-Ha-ras, c-jun, p53 and nm23. Furthermore, A11 cells exhibited lower motile and invasive abilities than P29 cells. These results suggest that the apoptosis-resistant phenotype is an important factor for determining the metastatic ability of A11 cells. Supporting this, P29 cells became more apoptosis-resistant after treatment of the cells with dimethylsulfoxide which is reported to enhance the experimental metastatic potential of the cells.
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PMID:Resistance to apoptosis induced by microenvironmental stresses is correlated with metastatic potential in Lewis lung carcinoma. 1065 7

2-Amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP), a compound found in cooked meat, is a mammary gland carcinogen in female Sprague-Dawley rats. PhIP-induced rat mammary gland carcinomas were examined for mutations in several genes (exons) known to regulate cell growth and apoptosis, including p53 (4-8), p21(Waf1) (coding region), Apc (14, 15), B-catenin (3), E-cadherin (9,13,15), Bcl-x (coding region), Bax (3), IGFIIR (28), and TGFBIIR (3). DNA from 30 carcinomas was examined by single-strand conformation polymorphism analysis, but no mutations were detected in these genes or gene regions. DNA from carcinomas and matching normal tissue were further screened for allelic imbalance by using a polymerase chain reaction-based approach with primers to known microsatellite regions located throughout the rat genome. Of 53 markers examined, 12 revealed allelic imbalance. Microsatellite instability (MSI) was detected at two markers, one on chromosome 4 and one on chromosome 6. Sixty-five percent and 96% of all carcinomas examined (N=23) showed MSI at these loci on chromosomes 4 and 6, respectively, supporting the notion that MSI plays a role in PhIP-induced mammary carcinogenesis. Loss of heterozygosity (LOH), an indication of a possible tumor suppressor gene, was observed at 10 markers distributed on chromosomes 3, 10, 11, 14, and X. The frequency of LOH at these markers was 75-94%, supporting that the regions of allelic imbalance were largely similar for the PhIP-induced carcinomas examined in this study. When PhIP-induced carcinomas from rats placed on high-fat and low-fat diet were compared, no unique regions of allelic imbalance or statistical differences in the frequency of allelic imbalance were observed. Therefore, the high-fat diet, known to be a promoter of PhIP-induced rat mammary carcinogenesis, did not appear to influence allelic imbalance in the carcinomas. Interestingly, 7,12-dimethylbenz[a]-anthracene-induced mammary carcinomas did not show allelic imbalance at 11 of the 12 loci that showed allelic imbalance in PhIP-induced carcinomas. These findings suggest that distinct chemical carcinogens induce different patterns of allelic imbalance during rat mammary carcinogenesis. Since several of the known genes involved in carcinogenesis did not harbor mutations in PhIP-induced carcinomas, further studies are needed to clarify the critical genes involved in PhIP-induced mammary carcinogenesis and to determine whether regions of LOH harbor potentially novel tumor suppressor genes involved in this disease.
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PMID:Genomic imbalance in rat mammary gland carcinomas induced by 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine. 1065

Gastric cancer, the second most common cancer in the world, kills about one million people a year, almost half of whom are Chinese. Chinese, Japanese and Koreans as well as east Europeans top the list with over 40 per 100,000 population per year, with a wide margin over Americans, Indians and Zimbabweans in whom the rates are below 1 per 100,000. The excellent prognosis of early gastric cancer is well established, and survival of cancer involving beyond the submucosa remains poor and there is little new in management. However, recent years have witnessed a breakthrough in the understanding of causative factors and molecular genetic abnormalities in gastric cancer that should pave the way for prevention, early detection and prognostication. Established carcinogens for gastric cancer now include Helicobacter pylori and N-nitroso compounds; other causative factors include salt and salted food intake, cigarette smoking, male sex, and familial genetic abnormalities. H. pylori infection increases cancer risk by about 5 in a 10-year period. Diet high in salt carries a relative risk of up to 6, and a highly significant correlation between 24 h urinary salt content and incidence of gastric cancer has been shown in 24 countries. The risk from smoking and male sex is under 2. Many N-nitroso compounds, which come from nitrites, which in turn come from nitrates in food following bacterial transformation in a hypochlorhydric environment, are established carcinogens in animals, but their risk for human gastric cancer is still debatable. The intestinal type of gastric cancer, according to Correa's hypothesis, develops from chronic inflammation leading to intestinal metaplasia, dysplasia and cancer, and is more associated with H. pylori and early gastric cancer. The diffuse type of gastric cancer does not go through these precancerous conditions and moves straight from inflammation to cancer. Associated with inflammation are an increase in proliferation and apoptosis, and this fine balance between proliferation and apoptosis may be uncoupled by genetic mutations. It is believed that as a result of the accumulation of molecular genetic abnormalities, a cancer eventually develops and metastasizes. p53 mutation, cyclin overexpression (especially in intestinal type), microsatellite instability, down regulation of E-cadherin (especially in diffuse type), and telomerase reactivation are some prominent examples. These molecular abnormalities have the potential for screening, early detection and prognostication. Fruits and vegetables, green tea, alpha-tocopherol and other micronutrients such as selenium have been shown to reduce the risk for gastric cancer. In fact, it has been reported that diet consisting of vegetables and fruits, low in salt, together with the avoidance of cigarette smoking would prevent two-thirds to three-quarters of gastric cancer. Furthermore, eradication of H. pylori, and for that matter future vaccination, has the theoretical potential of preventing gastric cancer, and the potential use of COX2 inhibiting NSAID in inducing apoptosis may reverse precancerous conditions of the stomach. Both approaches are being intensely studied.
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PMID:9th Seah Cheng Siang Memorial Lecture: gastric cancer--where are we now? 1067 11

Due to its increasing incidence, esophageal adenocarcinoma and its precursor lesions have received increasing attention in recent years. The histopathologic steps in the process of malignant progression in Barrett's esophagus are well described and include the following: (a) metaplasia of the normal esophageal squamous epithelium to a specialized intestinal glandular epithelium, (b) development of dysplasia (classified histologically as low and high grade), and (c) development of adenocarcinoma characterized by invasive and metastatic potential. Intestinal metaplasia can be identified by the presence of goblet cells, the detection of which can be aided by finding mucin stained by Alcian blue at low pH. Despite this well-characterized sequence, the timing of the development of dysplasia and the subsequent transition to carcinoma and the risk of development of carcinoma in low- and high-grade dysplasia are not precisely known. In addition, there are problems in the identification of dysplasia, including sampling error and interobserver discrepancies among pathologists. A better understanding of the mechanisms of these events would allow early identification and elimination of high-risk lesions before adenocarcinoma with its attendant poor prognosis were able to develop. In order to better understand this process and to potentially identify early markers of malignant transformation, a variety of molecular studies have been carried out in recent years on adenocarcinoma and its precursor lesions in Barrett's esophagus. On the phenotypic level, increased expression and changes in pattern of expression of proliferation marker (Mib-1) Ki-67 antigen, overexpression of p53 protein, overexpression of growth factors such as epidermal growth factor (EGF), c-erbB2, and transforming growth factor (TGF)-a, decreased and abnormal expression of the cell adhesion molecule E-cadherin, and, in carcinomas, increased expression of serine proteases have all been described. A new area of interest is the family of rab proteins, which play an important role in maintaining cell polarity in the gastrointestinal tract. Increased expression of one of these proteins, rab11, has been described in low-grade, but not high-grade dysplasia. In cytogenetic studies, an increased S-phase fraction, followed by an increased tetraploid (4N) fraction and then aneuploidy, has been described. So far, the specific genes which have been most thoroughly investigated have been p53, APC, p16, and the sites of probable tumor suppressor genes, including 3p (FHIT), 13q, and 18q. With only a few exceptions (i.e., rab11 expression, and possibly mutations of FHIT), the numerous molecular abnormalities which have been described occur late in malignant progression, which means that the best marker which presently exists to identify high-risk lesions in Barrett's esophagus is the histologic identification of dysplasia in endoscopic biopsies, especially high-grade dysplasia. We are presently beginning studies using laser microdissection and competitive genomic hybridization (CGH), which could help to identify new chromosomal areas that might contain genes that are crucial in the early phases of malignant progression in Barrett's esophagus. In the future, identification of such early molecular events which predispose to carcinoma development will allow more precise and earlier risk assessment for individual patients, therefore, enabling more effective therapy.
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PMID:Malignant progression in Barrett's esophagus: pathology and molecular biology. 1069 36

The purpose of this study was to assess the prognostic effect of the expression of E-cadherin, beta-catenin and CD44 adhesion molecules in bladder carcinoma. 22 superficial and 18 invasive bladder tumour samples were studied by immunohistochemistry. The median follow-up was 24 months (range: 1-50 months). Loss of E-cadherin and beta-catenin immunoreactivity was found in 14 (35%) and 17 (43%) tumours, respectively, and was significantly associated with invasiveness, high grade and p53 overexpression. There was no correlation between CD44 variant expression and clinicopathological findings. Loss of E-cadherin expression was an independent predictor of poor survival in a multivariate analysis, when assessed with age, grade, stage and p53 status (hazards ratio adjusted (HRa)=4.45 [95% confidence interval (CI), 1.06-18.63]). This effect was particularly augmented in patients with invasive bladder cancer. When expression of E-cadherin and beta-catenin were evaluated simultaneously, loss of immunoreactivity of both proteins was a strong predictor of poor survival (HRa=13.06 [95% CI, 0.95-178.55]). The same pattern was found when progression-free survival in relation to these variables was assessed. In conclusion, assessment of E-cadherin and beta-catenin immunoreactivity may be a useful prognostic marker in bladder cancer complementary to established prognostic factors.
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PMID:Prognostic value of the expression of E-cadherin and beta-catenin in bladder cancer. 1070 37

Since gastric cancer is an exceptional heterogeneous tumor conflicting results have been obtained about the relationship between genotype and phenotype. From the molecular point of view gastric carcinoma diffuse type forms a distinct entity which is microsatellite stable, has almost no p53 mutations and exhibits in at least half of the cases mutations in the E-cadherin gene. In contrast, all other gastric carcinomas comprise a heterogeneous group of which about one third exhibits microsatellite instability (MSI) but no p53 protein stabilization or gene mutations. These tumors are either of pure intestinal (glandular) type or show large solid (medullary) tumor cell clusters. Thereby, in sporadic gastric cancer MSI is caused by loss of hMLH1 expression due to hypermethylation of the promotor region rather than by mutation of the gene itself. Tumors that are microsatellite stable (MSS) and show p53 alterations are either intestinal (about 70%) or a mixed-type encompassing at least 5% glandular and poorly differentiated diffuse components (about 30%). Whereas pure diffuse type gastric cancer is unlikely to develop from intestinal type carcinoma, this may, however, be the case in some advanced mixed-type gastric cancers.
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PMID:[Correlation between histological and molecular mechanisms of carcinogenesis in stomach cancer]. 1071 97


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