Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The review considers the epigenetic defects and their diagnostics in several hereditary disorders and tumors. Aberrant methylation of the promoter or regulatory region of a gene results in its functional inactivation, which is phenotypically similar to structural deletion. Screening tests were developed for Prader-Willi, Angelman, Wiedemann-Beckwith, and Martin-Bell syndromes and mental retardation FRAXE. The tests are based on allele methylation analysis by methylation-specific or methylation-sensitive PCR. Carcinogenesis-associated genes (RB1, CDKN2A, ARF14, HIC1, CDI, etc.) are often methylated in tumors. Tumors differ in methylation frequencies, allowing differential diagnostics. Aberrant methylation of tumor suppressor genes occurs in early carcinogenesis, and its detection may be employed in presymptomatic diagnostics of tumors.
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PMID:[Diagnostics for epigenetic pathology in hereditary and oncologic diseases]. 1512 25

Array-based comparative genomic hybridization (aCGH) allows the identification of DNA sequence copy number changes at high resolution by co-hybridizing differentially labelled test and control DNAs to a micro-array of genomic clones. The present study has analysed a series of 23 formalin-fixed, paraffin wax-embedded tissue samples of Barrett's adenocarcinoma (BCA, n = 18) and non-neoplastic squamous oesophageal (n = 2) and gastric cardia mucosa (n = 3) by aCGH. The micro-arrays used contained 287 genomic targets covering oncogenes, tumour suppressor genes, and DNA sequences localized within chromosomal regions previously reported to be altered in BCA. DNA sequence copy number changes for a panel of approximately 50 genes were identified, most of which have not been previously described in BCA. DNA sequence copy number gains (mean 41 +/- 25/BCA) were more frequent than DNA sequence copy number losses (mean 20 +/- 15/BCA). The highest frequencies for DNA sequence copy number gains were detected for SNRPN (61%); GNLY (44%); NME1 (44%); DDX15, ABCB1 (MDR), ATM, LAMA3, MYBL2, ZNF217, and TNFRSF6B (39% each); and MSH2, TERC, SERPINE1, AFM137XA11, IGF1R, and PTPN1 (33% each). DNA sequence copy number losses were identified for PDGFB (44%); D17S125 (39%); AKT3 (28%); and RASSFI, FHIT, CDKN2A (p16), and SAS (CDK4) (28% each). In all non-neoplastic tissue samples of squamous oesophageal and gastric cardia mucosa, the measured mean ratios were 1.00 (squamous oesophageal mucosa) or 1.01 (gastric mucosa), indicating that no DNA sequence copy number chances were present. For validation, the DNA sequence copy number changes of selected clones (SNRPN, CMYC, HER2, ZNF217) detected by aCGH were confirmed by fluorescence in situ hybridization (FISH). These data show the sensitivity of aCGH for the identification of DNA sequence copy number changes at high resolution in BCA. The newly identified genes may include so far unknown biomarkers in BCA and are therefore a starting point for further studies elucidating their possible role in Barrett's carcinogenesis.
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PMID:Array-based comparative genomic hybridization for the detection of DNA sequence copy number changes in Barrett's adenocarcinoma. 1522 37

The CDKN2A locus on human chromosome 9p21 encodes two tumor suppressors, p14(ARF) and p16(INK4A), which enhance the growth-suppressive functions of the retinoblastoma (Rb) and the p53 proteins, respectively. Conversely, the E6 and E7 oncoproteins of the high-risk human papillomaviruses (HPVs) causally associated with carcinogenesis of the uterine cervix contributes to tumor development by inactivating p53 and Rb. Nevertheless, a correlation between expression of p14(ARF)/p16(INK4A) and HPV infection in uterine cervix is less clear. To clarify this, we examined 25 cervical cancers and 11 normal uterine cervixes. HPV was detected in 21 of 25 cervical cancers (84%) and their subtype was determined by PCR-RFLP. Quantitative real-time RT-PCR assays showed overexpression of p14(ARF) mRNA in all 21 HPV-positive cases (100%). p16(INK4A) mRNA was overexpressed in 17 cases of the HPV-positive cases (81%). In four HPV-negative cancers, reduced expression of p14(ARF) mRNA was detected in two cases (50%) and reduced p16(INK4A) mRNA in three cases (75%). Our data indicate that the overexpression of p14(ARF) and p16(INK4A) strongly associates with HPV-positive cervical cancers and that reduced expression of p14(ARF) and p16(INK4A) correlates with HPV-negative cervical cancers. These findings may indicate that impaired p14(ARF) and p16(INK4A) mRNA expression contribute to tumor development in HPV-negative cervical cancers by failure to support p53 and Rb instead of their inactivation by HPV E6 and E7.
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PMID:Correlation between p14(ARF)/p16(INK4A) expression and HPV infection in uterine cervical cancer. 1531 81

In this report, we introduce the CDKN2A Database, an online database of germline and somatic variants of the CDKN2A tumor suppressor gene recorded in human disease through the year 2002, annotated with evolutionary, structural, and functional information. The CDKN2A Database improves upon existing resources by: 1) including both somatic mutations and germline variants, thereby adding the perspective of somatic cell carcinogenesis to that of hereditary cancer predisposition; 2) including information that assists with the interpretation of allelic variants, such as other primary data (sequences, structures, alignments, functional measurements, and literature references) and annotations (extensive text, figures, and a tree-based phylogenetic classification); and 3) providing the information in a format that allows a user to either download the database or to easily manipulate it online. We describe the database structure, content, current uses, and potential implications (http://biodesktop.uvm.edu/perl/p16).
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PMID:The CDKN2A database: Integrating allelic variants with evolution, structure, function, and disease association. 1536 86

Genomic microarray systems can simultaneously provide substantial genetic and chromosomal information in a relatively short time. We have analyzed genomic DNA from frozen sections of 30 cases of primary glioblastomas by GenoSensor Array 300 in order to characterize gene amplifications, gene deletions, and chromosomal information in the whole genome. Genes that were frequently amplified included RFC2/CYLN2 (63.3%), EGFR (53.3%), IL6 (53.3%), ABCB1 (MDR1) (36.7%), and PDGFRA (26.7%). Genes that were frequently deleted included (56.7%), FGFR2 (66.7%), MTAP (60.0%), DMBT1 CDKN2A (p16)/MTAP (50.0%), PIK3CA (43.3%), and EGR2 (43.3%), but deletion of RB1 or TP53 was rarely detected. Chromosomal gains were observed frequently for 7q (33.3%), 7p (20.0%), and 17q (13.3%). Loss of the 10q was frequently detected in 13 of 30 cases (46.7%). Loss of the entire chromosome 10 was seen in 9 of 30 cases (30.0%), and was often accompanied by EGFR amplification (7 cases, 77.8%). The GenoSensor Array 300 proved to be useful for identification of genome-wide molecular changes in glioblastomas. The obtained microarray profile can also yield valuable insight into the molecular events underlying carcinogenesis of brain tumors and may provide clues about clinical correlations, including response to treatment.
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PMID:Genetic analysis of human glioblastomas using a genomic microarray system. 1569 66

DUSP6/MKP-3 is identified as a candidate tumor suppressor gene for pancreatic cancer. The aim of this study was to elucidate the roles of DUSP6 in the pancreatic carcinogenesis through the pancreatic intraepithelial neoplasia and/or intraductal papillary-mucinous neoplasms, both of which are considered to be precursor lesions of invasive carcinoma of the pancreas, by comparing with involvements of other major tumor suppressive pathways. Expressions of DUSP6, CDKN2A, TP53, and SMAD4 were investigated by immunohistochemistry in a total of 206 lesions of dysplastic ductal precursors and carcinomas retrieved from 52 pancreata with invasive ductal carcinomas and 51 of those with intraductal papillary-mucinous neoplasms. The intensity of staining was evaluated in lesions at different atypical grades and statistically compared among them. Mutations of KRAS2 were analyzed by methods of the allele-specific oligonucleotide hybridization and nucleotide sequencing. In pancreata with invasive ductal carcinomas, expressions of DUSP6 were abrogated exclusively in the invasive carcinoma cells in contrast to its fairly preserved expressions in pancreatic intraepithelial neoplasia. In pancreata with intraductal papillary-mucinous neoplasms, abrogated expressions of DUSP6 were observed in a relatively small fraction of intraductal adenoma/borderlines and intraductal carcinomas. Most of the intraductal adenoma/borderline lesions with abrogation of DUSP6 harbored mutations of KRAS2. None of the molecules was associated with each other in any grade of lesions. Morphological variations of papillae of the intraductal papillary-mucinous neoplasms were evaluated and analyzed for their associations with abrogations of the molecules, which resulted in finding of no significant associations. Our results suggest that the abrogation of DUSP6 is associated exclusively with progression from pancreatic intraepithelial neoplasia to the invasive ductal carcinoma while it is potentially associated with initiation of intraductal papillary-mucinous neoplasms with mutated KRAS2, which is independent of other major tumor suppressive pathways in both types of neoplasms.
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PMID:Distinct progression pathways involving the dysfunction of DUSP6/MKP-3 in pancreatic intraepithelial neoplasia and intraductal papillary-mucinous neoplasms of the pancreas. 1583 94

Genome scanning at a 1-Mb resolution was undertaken in 29 lung cancer cell lines to clarify the distribution of homozygous (i.e., both allele) deletions along lung cancer genomes, using a high-resolution single nucleotide polymorphism array. Eighteen regions, including two known tumor suppressor loci, CDKN2A at 9p21 and FHIT at 3p14, were found homozygously deleted. Frequencies of deletions at the 18 regions were evaluated by genomic polymerase chain reaction in 78 lung cancer cell lines. Seven regions, 2q24, 3p14, 5q11, 9p21, 9p23, 11q14, and 21q21, were homozygously deleted in two or more cell lines. The CDKN2A locus at 9p21 was most frequently deleted (20/78, 26%), and the deletions were detected exclusively in non-small-cell lung carcinomas (NSCLCs). The PTPRD (protein tyrosine phosphatase receptor type D) locus at 9p23 was the second-most frequently deleted (8/78, 10%), and the deletions were detected in both small-cell lung carcinomas (SCLC) and NSCLC. In addition, the 9p24 region was deleted in a NSCLC. In total, 24 (31%) cell lines carried at least one deletion on chromosome arm 9p, while deletions on the remaining chromosome arms were observed at most in four (5%) cell lines. Deletions at 9p24, 9p23, and 9p21 were not contiguous with one another, and preferential co-occurrence or mutual exclusiveness for the deletions at these three loci was not observed. Thus, it was indicated that 9p is the most frequent target of homozygous deletions in lung cancer, suggesting that the arm contains multiple lung tumor suppressor genes and/or genomic features fragile during lung carcinogenesis.
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PMID:Identification of chromosome arm 9p as the most frequent target of homozygous deletions in lung cancer. 1611 34

An association between functional polymorphisms of genes resulting in decreased detoxification of carcinogens or DNA repair and aberrant promoter methylation is an attractive hypothesis in lung carcinogenesis. The genotypes at polymorphic sites of the glutathione S-transferase (GST) M1 (null/wildtype) and P1 (nucleotide 2627 A/G), myeloperoxidase (MPO) (nucleotide -463 G/A), X-ray repair cross-complementing group 1 (XRCC1) (nucleotides 26304 C/T; 28152 G/A), and NADPH quinine oxidoreductase (NQO1) (nucleotide 609 C/T) genes in 75 Chinese patients with non-small cell lung cancer (NSCLC) were characterized with polymerase chain reaction-restriction fragment length polymorphism. Results were correlated with aberrant methylation of the CDKN2A (alias p16(INK4A)), retinoic acid receptor beta (RARB), methylguanine-DNA methyltransferase (MGMT), and death-associated-protein (DAP) kinase genes in the tumors. In comparison with an age-matched control, none of the polymorphisms were associated with increased lung cancer risks. In male patients, however, the MPO -463 GG homozygous state was associated with CDKN2A (alias p16(INK4A)) methylation (odds ratio OR=3.63, 95% confidence interval CI=1.26-10.51), and the XRCC1 26304 T allele in the heterozygous/homozygous state was associated with methylation of CDKN2A (OR=6.13, 95% CI=1.55-24.16) and RARB (OR=7.67, 95% CI=1.62-36.18). In female patients, the GSTP1 G allele in the heterozygous/homozygous state was associated with RARB methylation (OR=18.0, 95% CI=0.76-427.29). These results showed that functional deficiencies in metabolic pathways that protect cells from carcinogen induced DNA damage might be linked to aberrant promoter methylation of the CDKN2A and RARB genes during lung carcinogenesis.
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PMID:Polymorphisms of the GSTM1, GSTP1, MPO, XRCC1, and NQO1 genes in Chinese patients with non-small cell lung cancers: relationship with aberrant promoter methylation of the CDKN2A and RARB genes. 1615 95

The gene that encodes methylthioadenosine phosphorylase (MTAP), an enzyme involved in adenine and methionine salvage pathways, is located on chromosome 9p21 telomeric to the p16INK4A/CDKN2A tumor suppressor gene. Inactivation of the p16INK4A/CDKN2A gene occurs by three different mechanisms: hypermethylation of the gene promoter, intragenic mutation coupled with loss of the second allele, and homozygous deletion. Immunohistochemical labeling for the p16INK4A/CDKN2A gene product parallels gene status but does not elucidate the mechanism of gene inactivation. Since the MTAP gene is often co-deleted with p16INK4A/CDKN2A, concurrent immunolabeling for both proteins can identify cases with homozygous p16INK4A/CDKN2A gene deletion. MTAP loss itself has therapeutic implications since it may confer selective sensitivity to inhibitors of de novo purine biosynthesis, such as L-alanosine. Twelve tissue microarrays were constructed from 92 cases of Barrett-associated adenocarcinomas and precursor lesions and 112 cases of gastric adenocarcinoma and precursor lesions comprising 1161 individual cores. Multiple cores were arrayed from any given case, and when available, included the entire histologic spectrum of intestinal metaplasia-dysplasia-carcinoma. Tissue microarrays were labeled with monoclonal antibodies against MTAP protein (clone 6.9, Salmedix, Inc) and p16 (clone 16P07, Neomarkers). Complete loss of labeling was considered negative, while any labeling (p16: nuclear; MTAP: cytoplasmic and nuclear) was considered positive. Loss of MTAP labeling occurred exclusively in conjunction with loss of p16 labeling, confirming that the previous findings from this group that concurrent loss of MTAP and p16 labeling is a surrogate marker of 9p21 homozygous deletions. Complete loss of MTAP and p16 was seen in 4 of 25 (16%) patients with Barrett's esophagus, 4 of 18 (22%) with low-grade dysplasia, 5 of 39 (13%) with high-grade dysplasia, 17 of 78 (22%) with invasive adenocarcinoma, and 8 of 36 (22%) of metastases. There were 7 cases of esophageal adenocarcinoma with loss of both MTAP and p16 for which precursor lesions were available. In 6 on these 7 cases (85%), the precursor lesion(s) had loss of both MTAP and p16. Lack of MTAP and p16 expression was seen in 11 of 106 (10%) cases of gastric adenocarcinoma. All metaplastic (30 biopsies from 20 cases) and dysplastic (15 biopsies from 13 cases) gastric tissues had both intact MTAP and p16INK4A/CDKN2A gene products. No precursor lesions were available from the gastric cancers that had loss of both MTAP and p16. Two benign gastric hyperplastic polyps also had intact p16 and MTAP. Concurrent MTAP and p16 loss detected by immunohistochemistry can serve as a convenient surrogate for p16INK4A/CDKN2A gene homozygous deletion in archival tissues. Inactivation of p16INK4A/CDKN2A by homozygous deletion appears to be an early event in Barrett carcinogenesis, occurring in noninvasive precursor lesions, including nondysplastic Barrett mucosa, in subsets of cases. In the absence of MTAP, cells depend exclusively on the de novo synthesis pathway for production of adenosine. This loss of MTAP during 9p21 homozygous deletion might be exploited therapeutically using de novo purine synthesis antimetabolites to treat a subset of invasive gastroesophageal adenocarcinomas and esophageal precursor lesions.
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PMID:Concordant loss of MTAP and p16/CDKN2A expression in gastroesophageal carcinogenesis: evidence of homozygous deletion in esophageal noninvasive precursor lesions and therapeutic implications. 1622 17

Pancreatic ductal adenocarcinoma is one of the most fatal malignancies. Intensive investigation of molecular pathogenesis might lead to identifying useful molecules for diagnosis and treatment of the disease. Pancreatic ductal adenocarcinoma harbors complicated aberrations of alleles including losses of 1p, 6q, 9p, 12q, 17p, 18q, and 21q, and gains of 8q and 20q. Pancreatic cancer is usually initiated by mutation of KRAS and aberrant expression of SHH. Overexpression of AURKA mapping on 20q13.2 may significantly enhance overt tumorigenesity. Aberrations of tumor suppressor genes synergistically accelerate progression of the carcinogenic pathway through pancreatic intraepithelial neoplasia (PanIN) to invasive ductal adenocarcinoma. Abrogation of CDKN2A occurs in low-grade/early PanIN, whereas aberrations of TP53 and SMAD4 occur in high-grade/late PanIN. SMAD4 may play suppressive roles in tumorigenesis by inhibition of angiogenesis. Loss of 18q precedes SMAD4 inactivation, and restoration of chromosome 18 in pancreatic cancer cells results in tumor suppressive phenotypes regardless of SMAD4 status, indicating the possible existence of a tumor suppressor gene(s) other than SMAD4 on 18q. DUSP6 at 12q21-q22 is frequently abrogated by loss of expression in invasive ductal adenocarcinomas despite fairly preserved expression in PanIN, which suggests that DUSP6 works as a tumor suppressor in pancreatic carcinogenesis. Restoration of chromosome 12 also suppresses growths of pancreatic cancer cells despite the recovery of expression of DUSP6; the existence of yet another tumor suppressor gene on 12q is strongly suggested. Understanding the molecular mechanisms of pancreatic carcinogenesis will likely provide novel clues for preventing, detecting, and ultimately curing this life-threatening disease.
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PMID:Molecular mechanisms of pancreatic carcinogenesis. 1636 14


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