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: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The FHIT (fragile histidine triad) gene on chromosome 3p14 is a candidate tumor suppressor gene, and its transcripts are shown to be abnormal in several human cancers. We examined 40 leukemia samples for the alterations of FHIT transcripts by reverse transcriptase-polymerase chain reaction (RT-PCR) and direct sequencing. Intact FHIT mRNA was not detected in two patients with acute myeloid leukemia (AML) and in one patient with chronic lymphocytic leukemia (CLL). The three cases expressed only an aberrant FHIT mRNA lacking exons 3 to 6 (FHIT delta 3-6 mRNA), which could encode a polypeptide of 13 amino acids. Southern blot analysis on two samples from these cases showed no rearrangements of the FHIT gene. Although intact FHIT mRNA was detected as the main band in the remaining 37 samples, 33 of them (14 of 14 AML, 11 of 13 chronic myeloid leukemia, five of five acute lymphocytic leukemia, and three of five CLL) expressed aberrant FHIT delta 3-6 mRNA. We barely detected the FHIT delta 3-6 mRNA in only one of 25 normal control samples. Our results suggest that loss of the normal FHIT function may be involved in the genesis of at least some human leukemias and that expression of aberrant FHIT transcripts is rather specific and frequent in leukemia samples.
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PMID:Decreased or altered expression of the FHIT gene in human leukemias. 917 Feb 14

FHIT (fragile histidine triad gene), a candidate tumor suppressor gene, was recently identified and cloned at chromosome 3p14.2. Alterations of this gene have been reported in a number of primary human tumors, including colorectal, esophageal, gastric and lung carcinomas. However, some reports have found no abnormalities in this gene. We investigated a total of 63 primary esophageal tumors, nine esophageal cancer cell lines and 17 ulcerative colitis-associated neoplasms (UCANs) for alterations of FHIT. In 13 esophageal tumors, we employed overlapping reverse transcriptase-PCRs (RT-PCRs) to amplify and sequence the complete open reading frame of FHIT. One of 13 primary esophageal tumors analysed by RT-PCR expressed no detectable FHIT transcript; the remaining 12 expressed normal-sized transcripts with wild-type open reading frame sequences. In an additional 50 esophageal tumors, the polymorphic microsatellite loci D3S1300 and D3S1313 were used to evaluate loss of heterozygosity (LOH) at 3p14.2. Eleven of these 50 tumors showed LOH at one or both loci. In all these 11 tumors, genomic PCR and direct sequencing of FHIT exons 5-9 was performed. This analysis revealed that none of these 11 primary esophageal tumors contained any alterations in the FHIT open reading frame or adjacent intron sequences. Finally, among 17 UCANs, the in vitro synthesized protein (IVSP) assay detected no truncated protein products, nor were there any abnormalities in size or DNA sequence of FHIT RT-PCR products. However, in six of nine esophageal carcinoma cell lines, no FHIT RT-PCR product was detectable using either of the overlapping primer sets. Genomic PCR and direct sequencing of exons 5-9, also performed in these nine cell lines, revealed wild-type sequence in eight cell lines; however, one cell line contained no exon 5 PCR product. This cell line also lacked detectable FHIT transcript. These data suggest that the open reading frame of FHIT is not important in the development or progression of most primary esophageal carcinomas or UCANs, although lack of expression of the FHIT transcript may be common in esophageal cancer-derived cell lines. The possibility of an additional tumor suppressor gene at chromosome 3p14.2 remains to be evaluated.
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PMID:FHIT gene alterations in esophageal cancer and ulcerative colitis (UC). 923 82

The FHIT (fragile histidine triad) gene has been isolated from the chromosome region 3p14.2, which includes the fragile site locus FRA3B and the breakpoint of the t(3;8) of familial renal carcinoma. FHIT has been suggested to be a candidate tumor suppressor gene for digestive tract carcinomas. To evaluate the significance of FHIT gene abnormalities in gastric carcinogenesis, we examined the allelic status and transcripts of the gene in 23 primary gastric carcinomas as well as 7 gastric carcinoma cell lines. Four of the seven (57%) cell lines exhibited homozygous deletions of variable sizes at 3p14.2 all of which included D3S1300, which is located close to, or within, FRA3B. However, only 2 of 16 (13%) informative cases showed loss of heterozygosity at D3S1300 in the primary tumors. Direct analysis by reverse transcriptase polymerase chain reaction failed to reveal abnormal transcripts, including exon skipping and sequence changes, in the primary tumors or in the cell lines without homozygous deletions. These results suggest that FHIT gene abnormalities are infrequent in primary gastric carcinomas and that the frequent homozygous deletions seen in cell lines might simply reflect the plasticity of the genome at FRA3B under culture conditions.
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PMID:Analysis of the fragile histidine triad gene in primary gastric carcinomas and gastric carcinoma cell lines. 929 Sep 61

TSG101 has been identified as a candidate tumor suppressor gene and abnormal transcripts have been identified in a substantial fraction of breast cancers. To determine whether TSG101 expression is commonly altered in other tumors, a series of 15 primary and metastatic prostate cancers were analysed by reverse transcriptase-PCR amplification. Abnormal transcripts with extensive deletions in the coding region were found in nine of these tumors, while only the normal transcript was found in control and benign prostatic hypertrophy tissues. More than one abnormal transcript was found in four of these nine cases and distinct abnormal TSG101 transcripts were found in separate biopsies taken from one tumor. Importantly, the normal TSG101 transcript was undetectable in two metastatic prostate cancers, indicating the absence of TSG101 protein. Sequence analysis demonstrated that there were at least six distinct deletions, with four of these deletions found in more than one tumor sample. The most commonly identified deletion, from bp 153 to 1055, was identical to a deletion reported previously in breast cancer. These results demonstrate that TSG101 transcripts are frequently abnormal in prostate cancer and suggest that loss of TSG101 protein contributes to disease development or progression.
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PMID:Frequent abnormalities of TSG101 transcripts in human prostate cancer. 944 60

The p73 gene is a candidate tumor suppressor gene that has significant homology to p53. Thus far, p73 has not been investigated in hematopoietic malignancies. We used single-strand conformation polymorphism analysis to examine 60 de novo acute myelogenous leukemia (AML) patients for p73 mutations in exons 4, 6 and 7, which are homologous to the most frequently mutated exons in p53. Mutations were not found, but we did identify polymorphisms in exons 4 and 7. We also examined p73 RNA expression in 15 AML samples, eight cell lines, and eight normal bone marrows using the reverse transcriptase/polymerase chain reaction assay. All 31 RNA samples had p73 expression. Fourteen RNA samples were informative for allelic expression, being heterozygous for a polymorphism in codon 173 of exon 4. The two normal bone marrows and the K562 cell line had evidence of biallelic expression while six of 10 AML patients and the Kasumi (AML) cell line had monoallelic expression. These data suggest that functional p73 mutations in exons 4, 6 and 7 do not occur in most de novo AML patients. In addition, biallelic expression of p73 occurs in normal bone marrows, some AML samples, and specific cell lines. Lastly, monoallelic p73 expression appears to be common in de novo AML.
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PMID:p73 mutations and expression in adult de novo acute myelogenous leukemia. 1040 Apr 12

The p73 gene, a member of the p53 family, is a new candidate tumor suppressor gene. To investigate the possibility of genetic alteration of p73 in leukemia and lymphoma, we examined 55 cell lines and 39 patient samples together with 17 nonhematopoietic cancer cell lines. Gene expression of p73 was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in cell lines (5 of 7 pre B/B-acute lymphoblastic leukemia [ALL], 13 of 21 T-ALL/lymphoblastic lymphomas [LBL], 9 of 10 B-non-Hodgkin's lymphomas [B-NHL], 8 of 9 acute myelogenous leukemias [AML], 2 of 2 T-NHL, 3 of 3 multiple myeloma), and in patient samples (16 of 23 pre B-ALL, 5 of 8 T-ALL/LBL, 5 of 8 B-NHL). PCR-single-strand conformation polymorphism (SSCP) of cDNAs showed no mutation in 43 p73-expressing cell lines within the regions that corresponded to the 5 mutational hotspots of the p53 gene. Neither homologous deletion nor rearrangement of the p73 gene were found by Southern blot analysis in any of the cell lines that lack expression of p73. In contrast to prior published data, analysis of a polymorphic site showed that the p73 gene was expressed biallelically in cell lines and normal peripheral blood. Notably, the p73-negative cell lines were hypermethylated at a CpG island in the 5' untranslated region of the p73 mRNA, and treatment of these cell lines with 5-azacytidine (5-AC), a demethylation reagent, induced p73 expression. Taken together, we found that a sizable proportion (32%) of ALL/B-NHL cell lines and primary tumors had negligible or limited expression of the p73 gene associated with hypermethylation of the gene. These findings suggest that silencing of the p73 gene by hypermethylation may contribute to development and/or progression of lymphoid neoplasms.
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PMID:Loss of p73 gene expression in leukemias/lymphomas due to hypermethylation. 1041 5

Loss of heterozygosity of chromosome 10q has been reported in hepatoma. Areas with a high rate of loss of genetic material could harbor putative tumor suppressor genes. PTEN/MMAC1, a candidate tumor suppressor gene located at chromosome 10q23.3, has recently been identified and found to be homozygously deleted or mutated in several different types of human tumors. To determine whether the PTEN/MMAC1 gene is a target of 10q loss of heterozygosity in hepatoma, we examined 42 primary hepatomas for mutations in PTEN/MMAC1 by using nested reverse transcriptase polymerase chain reaction (RT-PCR) of the RNA and single-stranded conformation polymorphism (SSCP) analysis of all genomic exons. Although 2 of 42 hepatoma tissues had aberrant transcripts, 5 matched noncancerous liver tissues also had aberrant transcripts. Southern blot analysis of the entire genomic DNA revealed no genomic change. Therefore, like the TSG101 or FHIT gene, aberrant transcripts of PTEN/MMAC1 using the nested RT-PCR method were a common phenomenon for both cancerous and noncancerous liver tissues, which may not be related to oncogenesis. None of the 42 cases had small deletions, point mutations, or insertions. Our results suggest that the PTEN/MMAC1 gene may not play a role in the pathogenesis of hepatoma.
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PMID:Mutation analysis of the putative tumor suppressor gene PTEN/MMAC1 in hepatocellular carcinoma. 1070 74

Loss of heterozygosity (LOH) on chromosome arm 7q31 is found in many prostate tumors. Such alterations are generally associated with inactivation of tumor suppressor genes. It has been shown previously that the main region of LOH at 7q31 spans the interval between the D7S486 and D7S2460 microsatellite loci, which contains several candidate tumor suppressor genes (TSG) such as TES, CAV2, CAV1, MET, CAPZA2, ST7 and WNT2. We tested 41 human sporadic prostate tumors for 7q31 LOH by using 5 polymorphic markers overlapping the critical region and used a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assay to study the expression of the 7 candidate TSGs located in this genomic region. We found that CAV1, CAV2, MET and TES mRNA expression was lower in prostate tumors than in normal prostate tissues. Our immunohistochemical results and previously published data on the compartmental expression of these messenger RNAs in stromal and epithelial cells suggest that TES is the best candidate tumor suppressor gene at 7q31.
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PMID:Extensive analysis of the 7q31 region in human prostate tumors supports TES as the best candidate tumor suppressor gene. 1525 54

Deleted in malignant brain tumors 1 (DMBT1) gene was recently isolated on chromosome 10q25.3-26.1 and has been proposed as a putative candidate tumor suppressor for brain, esophageal, gastric, colorectal, and lung cancer. However, little is known about the association of DMBT1 with oral squamous cell carcinoma (OSCC). To study the role of DMBT1 gene in OSCC oncogenesis, we examined 9 OSCC derived cell lines and 45 primary OSCC tissue specimens with respective normal tissues. Semi-quantitative reverse transcriptase chain reaction (RT-PCR) analysis revealed down-regulation or deletion of DMBT1 expression in all of the 9 cell lines and in 18 (40%) of 45 primary OSCC tissues. Additionally, 57 OSCC tissue specimens were examined by immunohistochemical staining of protein showing down-regulation of DMBT1 protein in 31 (56.1%) of the 57 primary OSCC tissue specimens. To assess restoration of DMBT1 expression by demethylation of promoter region, the 9 cell lines were treated with 5-aza-2-deoxycytidine (5-Aza-C), one of the DNA demethylating agents. Six (66.7%) of 9 cell lines demonstrated restoration of DMBT1 expression after 5-Aza-C treatment. These results suggest that DMBT1 gene is involved in OSCC oncogenesis and/or progression and that methylation of promoter region is one of the important mechanisms suppressing the DMBT1 gene expression.
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PMID:Down-regulation of DMBT1 gene expression in human oral squamous cell carcinoma. 1575 18

Malignant pleural mesothelioma (MPM) is a highly lethal, poorly understood neoplasm that is typically associated with asbestos exposure. We performed transcriptional profiling using high-density oligonucleotide microarrays containing approximately 22,000 genes to elucidate potential molecular and pathobiological pathways in MPM using discarded human MPM tumor specimens (n = 40), normal lung specimens (n = 4), normal pleura specimens (n = 5), and MPM and SV40-immortalized mesothelial cell lines (n = 5). In global expression analysis using unsupervised clustering techniques, we found two potential subclasses of mesothelioma that correlated loosely with tumor histology. We also identified sets of genes with expression levels that distinguish between multiple tumor subclasses, normal and tumor tissues, and tumors with different morphologies. Microarray gene expression data were confirmed using quantitative reverse transcriptase-polymerase chain reaction and protein analysis for three novel candidate oncogenes (NME2, CRI1, and PDGFC) and one candidate tumor suppressor (GSN). Finally, we used bioinformatics tools (ie, software) to create and explore complex physiological pathways. Combined, all of these data may advance our understanding of mesothelioma tumorigenesis, pathobiology, or both.
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PMID:Identification of novel candidate oncogenes and tumor suppressors in malignant pleural mesothelioma using large-scale transcriptional profiling. 1592 Jan 67


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