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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fifty cases of colorectal adenocarcinoma were immunohistochemically examined for the relationship between distribution of plasminogen activators (PAs) and the degree of differentiation of cancer cells as reflected by carcinoembryonic antigen (CEA) expression as well as tumor cell kinetics. The A chain of urokinase-type PA (u-PA-A) was mainly observed in the apical portions of highly differentiated cancer cells. Increased expression and change in localization to the cytoplasm were found with progressive dedifferentiation. The numbers of DNA polymerase alpha (pol. alpha) positive cancer cells also increased in line with u-PA-A expression. The B chain of u-PA (u-PA-B), and the A and B chains of tissue-type PA (t-PA-A and -B) did not show similar alteration. The present findings suggest that the distribution of u-PA-A in colorectal carcinoma tissues, the degree of tumor differentiation, and the proliferation kinetics of cancer cells are closely related.
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PMID:Immunohistochemical analysis of plasminogen activator expression in human colorectal carcinomas: correlation with CEA distribution and tumor cell kinetics. 190 Nov 19

A large number of mutants that are temperature sensitive (ts) for growth have been isolated from mouse mammary carcinoma FM3A cells by an improved selection method consisting of cell synchronization and short exposures to restrictive temperature. The improved method increased the efficiency of isolating DNA ts mutants, which showed a rapid decrease in DNA-synthesizing ability after temperature shift-up. Sixteen mutants isolated by this and other methods were selected for this study. Flow microfluorometric analysis of these mutants cultured at a nonpermissive temperature (39 degrees C) for 16 h indicated that five clones were arrested in the G1 to S phase of the cell cycle, six clones were in the S to G2 phase, and two clones were arrested in the G2 phase. The remaining three clones exhibited 8C DNA content after incubation at 39 degrees C for 28 h, indicating defects in mitosis or cytokinesis. These mutants were classified into 11 complementation groups. All the mutants except for those arrested in the G2 phase and those exhibiting defects in mitosis or cytokinesis showed a rapid decrease in DNA synthesis after temperature shift-up without a decrease in RNA and protein synthesis. The polyomavirus DNA cell-free replication system, which consists of polyomavirus large tumor antigen and mouse cell extracts, was used for further characterization of these DNA ts mutants. Among these ts mutants, only the tsFT20 strain, which contains heat-labile DNA polymerase alpha, was unable to support the polyomavirus DNA replication. Analysis by DNA fiber autoradiography revealed that DNA chain elongation rates of these DNA ts mutants were not changed and that the initiation of DNA replication at the origin of replicons was impaired in the mutant cells.
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PMID:Isolation of temperature-sensitive cell cycle mutants from mouse FM3A cells. Characterization of mutants with special reference to DNA replication. 215 21

DNA polymerase alpha is an endogenous DNA replication enzyme expressed in all cells in a proliferation cycle. An immunoperoxidase method and the monoclonal antibody to DNA polymerase alpha were used to identify proliferating cells in colorectal carcinomas (n = 35) and adenomas (n = 43). The labeling index (L.I.) in colorectal carcinomas was 51.6%, being significantly higher than 28.6% in adenomas. The L.I. in colorectal carcinomas correlated with clinical staging (stage I: 33.1%, stage II and III: 49.5%, stage IV and V: 66.9%). Furthermore, the L.I. had a tendency to elevate as carcinoma deeply invaded (pm: 25.8%, ss-s or a1-a2: 52.2%, si or ai: 67.5%). The L.I. in adenoma was related to the degree of atypia. The L.I. in adenomas with mild atypia, with moderate atypia, and cancer in adenoma were 18.3%, 31.5%, and 47.0%, respectively. And the L.I. of cancer in adenoma had no significant difference in advanced carcinomas (47.0% vs 51.6%). These results suggest that the L.I. is useful as a marker for evaluating the degree of biological malignancy of human colorectal carcinomas and the degree of histopathological atypia of adenomas.
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PMID:[Detection of proliferative cells in colorectal carcinomas and adenomas by monoclonal antibody to DNA polymerase alpha]. 227 35

Substantial evidence has implicated Epstein-Barr virus (EBV) in the aetiology of two human neoplasms, nasopharyngeal carcinoma (NPC) and Burkitt's lymphoma. This is supported by the presence of high antibody titres to EBV early antigen and virus capsid antigen, as well as antibody to two viral-associated enzymes, DNase and DNA polymerase. Patients with NPC, particularly the undifferentiated form, are commonly found to have EBV DNA in the tumour. Ito and others have presented strong epidemiological evidence that phorbol esters are related to the unusual geographic distribution of NPC in southeastern regions of China. There appears to be a close link between the widespread EBV infection of the Asian population and the distinct regional distribution in China of plants that produce diterpene ester. Naturally occurring phorbol esters are produced by plants of the Euphorbiaceae and Thymelaeaceae, which are used as traditional herbal medicines. Although it has been established that EBV can infect epithelial cells isolated from NPC as well as certain normal epithelial cells, there has been no in vitro evidence that EBV induces neoplastic transformation in normal human epithelial cells with or without exposure to phorbol esters. We report here evidence that transformation of normal human epithelial cells results from exposure to infectious EBV and that transformation is dependent on the presence of phorbol esters.
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PMID:Phorbol ester and Epstein-Barr virus dependent transformation of normal primary human skin epithelial cells. 244 17

A nasopharyngeal carcinoma tumour (designated C15) propagated in nude mice has been used to generate a large cDNA library that we have analysed for Epstein-Barr virus (EBV) gene expression. No gross alterations exist in viral DNA from C15 relative to other human isolates and the large deletion present in the B95-8 'prototype' viral strain established in marmoset cells is not found; C15 contains no linear virion DNA. In the cDNA library, of the six EBV nuclear antigens (EBNAs) expressed in latently infected B-lymphocytes, only clones for EBNA-1 are found. These data are confirmed by immunoblotting. Sequence analysis shows the EBNA-1 mRNA splicing pattern in the carcinoma to differ from that observed in B-lymphocytes. Further, contrary to observations with B-cell lines, most viral transcription in the tumour is localized onto the 'rightmost' region of the conventional EBV physical map. Transcripts identified corresponding to known genes include those for the latent membrane protein (LMP), the alkaline DNA exonuclease and probably the terminal protein; major transcripts are also derived from the BamHI D fragment and the region deleted in B95-8 EBV DNA. Novel transcripts have also been identified that proceed in an anti-sense direction to genes encoding functions associated with replication, such as the viral DNA polymerase. They contain a large, hitherto unidentified, open reading frame in the viral genome that is complementary to the putative function known as BALF3 and a smaller open reading frame complementary to BALF5 (the DNA polymerase gene). From the present studies we can conclude that: (i) EBV transcription patterns in the epithelial cells vary markedly from those identified previously in B-cells, reflecting differential use of promoters or splicing patterns. (ii) Transcription is tightly regulated and restricted in the C15 tumour with many latent genes, notably EBNAs 2-6, being 'switched off.' (iii) A family of cytoplasmic RNAs are transcribed in an antisense direction to a number of existing open reading frames in the EBV genome. (iv) There are a number of mutations in C15 transcripts relative to the B95-8 genome, some of which could result in amino acid alterations in proteins.
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PMID:EBV gene expression in an NPC-related tumour. 247 54

A salt-dependent DNA polymerase activity was demonstrated in the culture of an EBV-producing, lymphoblastoid cell line (NPC-204 cells) treated with 5-iodo-2'-deoxyuridine (IUdR). There was a high frequency of levels of antibody to this enzyme in sera of patients with nasopharyngeal carcinoma (NPC). In contrast, sera from healthy subjects had little or no neutralizing activity. The high antibody level appeared as early as stage 1 of the disease in many NPC patients. The levels of the antibody increased with the progression of the disease and declined in treated patients. The results strongly suggest that tests measuring serum antibody against EBV DNA polymerase activity can be used for early diagnosis and prognosis of NPC.
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PMID:Antibody against Epstein-Barr virus DNA polymerase activity in sera of patients with nasopharyngeal carcinoma. 254 74

NPC-KT cl.S61, a subclone derived from an epithelial-nasopharyngeal carcinoma hybrid cell line (NPC-KT), showed cytopathic changes characteristic of herpesvirus replication, including formation of multinucleated giant cells and inclusion bodies, when Epstein-Barr virus replicative cycle was induced by 5-iodo-2'-deoxyuridine. Acyclovir (an inhibitor of herpesvirus DNA polymerase), Epstein-Barr virus-immune human serum, or 2-deoxyglucose (an inhibitor of the glycosylation) interfered with syncytium formation, indicating that a virus-specified glycoprotein belonging to the late group is responsible for cell fusion induced by Epstein-Barr virus replication in cl.S61 cells.
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PMID:Cytopathic effects induced by Epstein-Barr virus replication in epithelial nasopharyngeal carcinoma hybrid cells. 254 26

In an attempt to develop an in vitro human cytomegalovirus (HCMV) latency model system, the growth characteristics of HCMV in a human thyroid papillary carcinoma cell line (TPC-1) were examined. When TPC-1 cultures preheated at 40.5 degrees for 48 hr were infected with HCMV and incubated at a supraoptimal temperature (40.5 degrees), the cultures could be maintained for at least 65 days without detection of infectious virus. In contrast, when the infected cultures were incubated at 37 degrees, HCMV persistently infected cultures were established. HCMV was reactivated from the latently infected cultures by decreasing the incubation temperature from 40.5 to 37 degrees, and the cultures subsequently entered into virus persistent infection. Although HCMV-specific polypeptides which comigrate with the immediate early virus polypeptides and nuclear antigens were continuously detectable in the majority (more than 95%) of the cells during the latent period, a detectable level of virus-specified DNA polymerase (one of the early virus proteins) was not induced, suggesting that the blockage of HCMV replication in the latently infected cultures occurs at the early stages of the HCMV replication cycle. Infectious center assay revealed that 0.002 to 0.2% of the cells contain an HCMV genome that can be activated during the latent period. The latently infected cells were susceptible to superinfection with homologous and heterologous strains of HCMV. In persistently infected cultures approximately 38% of the cells were lysed by reaction with HCMV immune serum and complement, whereas complement-mediated immune cytolysis could not be detected in the latently infected cultures. The data presented suggest that a temperature-sensitive cellular function(s) that controls the expression of the HCMV early functions plays an important role in maintenance of the HCMV genome in the latent state and reactivation of HCMV by decreasing the incubation temperature.
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PMID:Establishment and biological characterization of an in vitro human cytomegalovirus latency model. 282 70

Indomethacin and tetracaine, inhibitors of prostaglandin synthesis, inhibited production of infectious human cytomegalovirus (HCMV) in a human thyroid papillary carcinoma cell line (TPC-1) by 99.9% when added to cultures at the concentration of 2 x 10(-4) M during the first 24 hr after infection. Although immediate early virus proteins were synthesized at similar molar ratios in mock- and compound-treated cultures, induction of HCMV-specific DNA polymerase (one of the early virus proteins) was inhibited by treatment with these compounds, suggesting that the early stages of the virus growth cycle are most likely to be under the control of indomethacin or tetracaine action. We have previously developed an in vitro HCMV latency model system in TPC-1 cultures. This system was used to study the effect of these compounds on reactivation of the latent virus. When TPC-1 cultures preheated for 48 hr at 40.5 degrees were infected with HCMV and incubated at 40.5 degrees, the cultures could be maintained for 30 days without detection of infectious virus. The latent HCMV was reactivated within 10 days by reducing the incubation temperature from 40.5 to 37 degrees. However, when the latently infected cultures were treated with indomethacin or tetracaine immediately after being shifted to 37 degrees, reactivation of the latent virus was not observed.
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PMID:Inhibitors of prostaglandin synthesis inhibit growth of human cytomegalovirus and reactivation of latent virus in a productively and latently infected human cell line. 283 56

In an attempt to examine further the association between active Epstein-Barr virus (EBV) infection and the chronic fatigue syndrome (chronic EBV syndrome, or chronic or atypical mononucleosis), antibodies acting against EBV-specific DNase and DNA polymerase, which are expressed only during virus replication, were assayed. Serum samples from 25 healthy EBV-seropositive individuals neutralized 3.5 +/- 5.1 U (mean +/- SD) of DNase activity and 14.7 +/- 8.5 U of DNA polymerase activity. From these values were selected upper limits of anti-EBV enzyme activity of 17.9 and 31.3 U neutralized in normal individuals, respectively (representing the 95% confidence limit). Serum samples from six groups of subjects representing a variety of EBV-related illnesses were then studied. Only patients with notably elevated anti-EBV antibody titers to viral capsid antigen (VCA) (greater than 10,000) had elevated levels of anti-EBV DNase (38 to 56 U neutralized) and anti-EBV DNA polymerase (72 to 106 U neutralized). Three additional patients and two geriatric controls with average anti-EBV early antigen/VCA titers had slightly elevated levels of antibody to EBV DNA polymerase. IgA anti-VCA, anti-early antigen antibodies, or both, were also detected in the same patients who had high EBV DNase and polymerase antibody levels. These antibody profiles are similar to those in patients with nasopharyngeal carcinoma. Since three of the six patients with elevated anti-EBV enzyme antibody levels developed fatal lymphomas, patients with chronic EBV and this antibody profile might be in another illness category at risk for malignant disease.
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PMID:Antibodies to Epstein-Barr virus-specific DNase and DNA polymerase in the chronic fatigue syndrome. 284 38


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