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)

Loss of FHIT expression and p53 mutations are critical events in the early stages of lung carcinogenesis. The restoration of Fhit function in FHIT-negative cancer cells has been reported to cause tumour suppression by inhibition of cell proliferation and/or activation of apoptotic pathways. However, the studies designed to elucidate the biological role of Fhit and its potential interaction with p53 have produced conflicting results. We investigated here the effects of the simultaneous restoration of FHIT and p53 in Calu-1 cells by using a hormone-inducible gene expression system. We demonstrate that the restoration of FHIT expression reinforces the anti-proliferative effect associated with the simultaneous replacement of p53. Indeed, a more pronounced inhibition of cell proliferation associated with an earlier and higher induction of p21(waf1) mRNA and protein expression was observed in Fhit/p53-expressing cells compared with cells expressing p53 alone. This effect was not due to Fhit-mediated up-regulation of p53 expression; in fact p53 protein was expressed at the same level in both FHIT-positive and FHIT-negative cell clones. Consistent with this result, Fhit did not affect the expression of MDM2, a protein known to interact directly with p53 and target p53 for proteolytic degradation, thus down-regulating its activity.
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PMID:Effect of inducible FHIT and p53 expression in the Calu-1 lung cancer cell line. 1661 10

The MDM2 protein negatively regulates p53 expression level in modulating DNA repair, cell-cycle control, cell growth and apoptosis. Polymorphisms in the promoter region of the MDM2 gene have been shown to alter protein expression and may, thus, play a role in carcinogenesis. To test our hypothesis that the MDM2 promoter polymorphisms are associated with risk of lung cancer, we conducted a hospital-based, case-control study of 1026 non-Hispanic white patients newly diagnosed with lung cancer and 1145 cancer-free controls who were frequency-matched by age (+/-5 years), sex, ethnicity and smoking status. We genotyped for the MDM2 promoter G2580T (also called SNP309) and G2164A polymorphisms that have a minor allele frequency >0.05. The distributions of the MDM2-2580G variant allele and genotypes were significantly less common among the cases than among the controls (P = 0.038 and 0.045, respectively), but this was not evident for MDM2-2164G (P = 0.865 and 0.614, respectively). Compared with the MDM2-2580TT genotype, the MDM2-2580G variant genotypes were associated with a decreased risk of lung cancer [odds ratio = 0.81 and 95% confidence interval = 0.67-0.98 for GT, 0.83 (0.63-1.08) for GG, and 0.81 (0.68-0.97) for the combined GT/GG genotype]. However, no significant association was observed between the MDM2-2164G variant genotypes and lung cancer risk. Our results suggest that the MDM2-2580G allele may be a marker of reduced genetic susceptibility to lung cancer in the non-Hispanic white population, a finding that seems to contradict previous reports.
Carcinogenesis 2006 Oct
PMID:MDM2 gene promoter polymorphisms and risk of lung cancer: a case-control analysis. 1667 70

To identify oncogene amplification involved in ovarian carcinogenesis, we studied 21 ovarian carcinomas and 5 serous borderline tumors using conventional comparative genomic hybridization (CGH) and CGH to a genomic DNA microarray. Immunohistochemical analysis of the proteins encoded by the genes that were amplified frequently (FGF3/4, FGFR1, CCNE1, PAK1, JUNB, and MDM2) was performed on a tissue microarray comprising 254 cases of ovarian neoplasms. Regarding histologic type, characteristic patterns of copy number changes were revealed. They correlated with histologic tumor type and with intratumoral heterogeneity. Gain of FGF3/4 and CCNE1 was found in all serous carcinomas. Endometrioid carcinomas most frequently showed gain of JUNB (83%), KRAS2 (67%), MYCN (50%), ESR (50%), and CCND2 (50%). Of the serous borderline tumors, 80% harbored amplification of FGFR1 and MDM2 and a 75% gain of PIK3CA. Only CCNE1 immunoreactivity was significantly correlated with CGH results (P < .05) and postoperative survival (P < .05). Microarray-based genomic analysis in combination with immunohistochemical analysis was found to be a powerful technique for identification of clinically relevant gene amplification in human ovarian cancer.
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PMID:Analysis of gene amplification and prognostic markers in ovarian cancer using comparative genomic hybridization for microarrays and immunohistochemical analysis for tissue microarrays. 1675 89

A single nucleotide polymorphism (SNP) in the MDM2 promoter (a T to G exchange at nucleotide 309) has been found to be associated with tumor formation. Publication of this null report is important because an association between MDM2 SNP309 and lung cancer was previously reported in two independent studies. Our findings suggest that MDM2 SNP309 is not a strong factor in lung carcinogenesis. In addition, this is the first MDM2 SNP309 report on a population consisting of Caucasians in the United States and African-Americans. A strength of the study design is that the controls consist of both population and hospital controls.
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PMID:MDM2 SNP309 and SNP354 are not associated with lung cancer risk. 1689 50

A single nucleotide polymorphism (SNP309T>G) in the intronic promoter of MDM2 was recently found to accelerate carcinogenesis in early-onset cancer cases. This cancer acceleration presumably was due to increased SP1 binding, resulting in enhanced MDM2 transcriptional activation by estrogens. We evaluated MDM2 SNP309 in 343 familial breast cancer cases with known mutation status for CHEK2 1100delC, BRCA1 and BRCA2. Cancer acceleration was indeed observed in early-onset familial breast cancer cases (diagnosed <or= 51 years), with 16% of cases carrying the MDM2 SNP309 GG genotype as compared to 4% of late-onset cases (P = 0.029). The cancer acceleration was even more pronounced in the non-mutant familial breast cancer cases, with 17% of early-onset cases carrying MDM2 SNP309 GG as compared to 2% of late-onset cases (n = 214; P = 0.015). There was no evidence for an influence of estrogen signaling in the cancer acceleration by MDM2 SNP309, as there were no differences in the prevalence of MDM2 SNP309 GG among CHEK2 1100delC and BRCA2 mutant cases (with 90% ER-positive cancers) or BRCA1 mutant cases (10% ER-positive cancers). Nor did we observe differences in MDM2 SNP309 frequencies among 75 familial breast cancer cases of our cohort with known ER status. Overall, our data suggest that MDM2 SNP309 accelerates familial breast carcinogenesis, but that this acceleration is not influenced by estrogen signaling.
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PMID:MDM2 SNP309 accelerates familial breast carcinogenesis independently of estrogen signaling. 1708 Mar 8

The ARF tumor suppressor signals through p53 and other poorly defined anti-proliferative pathways to block carcinogenesis. In a search for new regulators of ARF signaling, we discovered a novel nuclear protein that we named NIAM (nuclear interactor of ARF and MDM2) for its ability to bind both ARF and the p53 antagonist MDM2. NIAM protein is normally expressed at low to undetectable levels in cells because of, at least in part, MDM2-mediated ubiquitination and proteasomal degradation. When reintroduced into cells, NIAM activated p53, caused a G1 phase cell cycle arrest, and collaborated with ARF in an additive fashion to suppress proliferation. Notably, NIAM retains growth inhibitory activity in cells lacking ARF and/or p53, and knockdown experiments revealed that it is not essential for ARF-mediated growth inhibition. Thus, NIAM and ARF act in separate anti-proliferative pathways that intersect mechanistically and suppress growth more effectively when jointly activated. Intriguingly, silencing of NIAM accelerated chromosomal instability, and microarray analyses showed reduced NIAM mRNA expression in numerous primary human tumors. This study identifies a novel protein with tumor suppressor-like behaviors and functional links to ARF-MDM2-p53 signaling.
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PMID:A novel nuclear interactor of ARF and MDM2 (NIAM) that maintains chromosomal stability. 1711 Mar 79

Human p53, unlike mouse p53, contains a polymorphic site at codon 72 in exon 4 encoding either an arginine amino acid (72R) or a proline residue (72P). The 72R form was shown to induce apoptosis better than the 72P form, partly owing to its ability to efficiently bind to the nuclear-export protein CRM1 and localize to the mitochondria. This polymorphism has also been associated with cancer predisposition and chemo-sensitivity. Further understanding of the in vivo significance of this polymorphism in carcinogenesis requires the generation of mouse models. We have thus evaluated if the polymorphism-specific effects of human p53 are retained in mouse cells. Though being transcriptionally active, both the human polymorphs were found to have lost their ability to differentially suppress growth and bind to CRM1 or MDM2 in mouse cells. Moreover, chimaeric proteins containing mouse exons 2-3 and human exons 4-11 have also lost the polymorphism-specific effects in human cells, suggesting that human exons 2-3 are important in regulating the polymorphism-specific effects. Furthermore, human p53 and the various chimaeric proteins were generally less effective in inhibiting growth of mouse cells compared to mouse p53, suggesting that mouse p53 is more potent than human p53 in suppressing growth, partly due to enhanced binding of MDM2 to human p53. The data together suggest that mouse cells may not provide an appropriate environment for the manifestation of the polymorphism-specific functional differences of human p53, and hence, cautions against the expression of full-length or chimaeric p53 proteins in mice to study the effects of the polymorphism.
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PMID:The codon 72 polymorphism-specific effects of human p53 are absent in mouse cells: implications on generation of mouse models. 1713 Aug 38

We have established 3 cell lines ORL-48, -115 and -136 from surgically resected specimens obtained from untreated primary human oral squamous cell carcinomas of the oral cavity. The in vitro growth characteristics, epithelial origin, in vitro anchorage independency, human papilloma-virus (HPV) infection, microsatellite instability status, karyotype and the status of various cell cycle regulators and gatekeepers of these cell lines were investigated. All 3 cell lines grew as monolayers with doubling times ranging between 26.4 and 40.8 h and were immortal. Karyotyping confirmed that these cell lines were of human origin with multiple random losses and gains of entire chromosomes and regions of chromosomes. Immunohistochemistry staining of cytokeratins confirmed the epithelial origin of these cell lines, and the low degree of anchorage independency expressed by these cell lines suggests non-transformed phenotypes. Genetic analysis identified mutations in the p53 gene in all cell lines and hypermethylation of p16INK4a in ORL-48 and -136. Analysis of MDM2 and EGFR expression indicated MDM2 overexpression in ORL-48 and EGFR overexpression in ORL-136 in comparison to the protein levels in normal oral keratinocytes. Analysis of the BAT-26 polyadenine repeat sequence and MLH-1 and MSH-2 repair enzymes demonstrated that all 3 cell lines were microsatellite stable. The role of HPV in driving carcinogenesis in these tumours was negated by the absence of HPV. Finally, analysis of the tissues from which these cell lines were derived indicated that the cell lines were genetically representative of the tumours, and, therefore, are useful tools in the understanding of the molecular changes associated with oral cancers.
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PMID:Establishment and characterization of Asian oral cancer cell lines as in vitro models to study a disease prevalent in Asia. 1727 94

As a major negative regulator of p53, the MDM2 oncogene plays an important role in carcinogenesis and tumor progression. MDM2 promotes p53 proteasomal degradation and negatively regulates p53 function. The mechanisms by which the MDM2-p53 interaction is regulated are not fully understood, although several MDM2-interacting molecules have recently been identified. To search for novel MDM2-binding partners, we screened a human prostate cDNA library by the yeast two-hybrid assay using full-length MDM2 protein as the bait. Among the candidate proteins, ribosomal protein S7 was identified and confirmed as a novel MDM2-interacting protein. Herein, we demonstrate that S7 binds to MDM2, in vitro and in vivo, and that the interaction between MDM2 and S7 leads to modulation of MDM2-p53 binding by forming a ternary complex among MDM2, p53 and S7. This results in the stabilization of p53 protein through abrogation of MDM2-mediated p53 ubiquitination. Consequently, S7 overexpression increases p53 transactivational activities, induces apoptosis, and inhibits cell proliferation. The identification of S7 as a novel MDM2-interacting partner contributes to elucidation of the complex regulation of the MDM2-p53 interaction and has implications in cancer prevention and therapy.
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PMID:Ribosomal protein S7 as a novel modulator of p53-MDM2 interaction: binding to MDM2, stabilization of p53 protein, and activation of p53 function. 1731 Sep 83

Epstein-Barr virus encoded latent membrane protein 1 (LMP1), an oncogenic protein, plays an important role in the carcinogenesis of nasopharyngeal carcinoma. The MDM2 gene is a cellular pro-oncogene that is abnormally up-regulated in human tumors. MDM2 is overexpressed in nasopharyngeal carcinoma, which is associated with the presence of EBV and cervical lymph node metastasis. Because MDM2 is capable of self-ubiquitination, and the ubiquitin proteasome pathway-dependent degradation is an important mechanism for regulating MDM2 levels in cells. Here we show that LMP1 augment MDM2 protein expression in dose-dependent level, and also lead to a drastic accumulation of ubiquitinated MDM2 species, this effect is associated with the stability of MDM2 modulated by LMP1. This is the first time to explain LMP1-regulated MDM2 through a post-ubiquitination mechanism.
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PMID:Ubiquitination of MDM2 modulated by Epstein-Barr virus encoded latent membrane protein 1. 1757 19


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