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)

Endometrial hyperplasia (EH) was found to coexist in 13 of 21 patients (cystic glandular hyperplasia, 13; adenomatous hyperplasia, 9) with endometrial adenocarcinoma (EC), but in only 44 of 940 patients with other than EC. In this study, blood type (A, B, H), c-myc translation products, estrogen receptor and DNA polymerase alpha were examined on endometrium of proliferative phase (EPP), EH and EC. Patient blood type products were shown in EH surrounding EC, and yet they were detected in only small portion or none of EC itself. H products were detected in EC of other than O type. c-myc translation products were shown in only a small portion of cancer cells. EPP had many ER positive cells and a few proliferating cells as they were shown by staining with anti-DNA polymerase alpha monoclonal antibody. EC can be divided into two types, one has few ER positive cells and many proliferating cells, other many ER positive cells and a few proliferating cells. In EH, the numbers of ER positive cells and DNA polymerase alpha positive cells were between those of EPP and EC. In a patient with atypical hyperplasia, high dose Medroxyprogesterone acetate (MPA) therapy induced that stratification and papillary growth of gland lining epithelia disappeared, and that cytoplasmic enlargement and vacuolation appeared. These findings were important histopathological changes in high dose MPA administration to EH and EC.
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PMID:[Diagnosis and treatment of endometrial hyperplasia]. 252 3

DNA polymerase alpha activity is associated with cell proliferation, independently of the cell cycle phase, and a simple and reproducible method for the immunohistochemical demonstration of DNA polymerase alpha has been developed. In an analysis of a total of 76 human breast cancer tissues using this procedure, the clinico-pathological findings revealed that only the estrogen receptor (ER) significantly correlated with the DNA polymerase alpha activity. Therefore, this suggests that ER-negative tumors had a higher proliferative activity.
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PMID:[A study of the proliferative activity of DNA polymerase alpha immunoreactivity in breast cancer]. 268 77

Nucleo-cytoplasmic distribution of estrogen receptors and DNA polymerase alpha activity in human endometrial adenocarcinoma cells (HEC-50 line) was evaluated after separation of nuclei following either homogenization or enucleation with cytochalasin B. About 30% of the estrogen receptor was found in the nuclear fraction after homogenization whereas 86% was found in the karyoplasts after enucleation. The total amounts of estrogen receptor per cell after homogenization and enucleation were not significantly different (14,000-17,000 binding sites/cell). Receptor measurements were carried out using the hydroxylapatite method after labeling with [3H]estradiol (5 nM [3H]E2 +/- 500 nM E2) at 30 degrees C for 3 h. About 20% of the DNA polymerase alpha activity was found in the nuclear fraction after homogenization, whereas 96% was found in the karyoplasts after enucleation. The average total activity (0.84 Units/10(6) cells) in homogenized cells was about 1/8 of the activity in karyoplasts. These results indicate that estrogen receptor and DNA polymerase alpha activity reside in the nucleus in intact HEC-50 cells. DNA polymerase alpha is translocated to the cytoplasmic fraction and inactivated after homogenization.
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PMID:Enucleation of human endometrial cells: nucleo-cytoplasmic distribution of DNA polymerase alpha and estrogen receptor. 370 33

Estradiol (E2) stimulates the proliferation of human endometrial adenocarcinoma cells of the Ishikawa line, which had been previously shown to respond to estrogen by increasing their levels of progesterone receptor and the specific activities of DNA polymerase alpha and alkaline phosphatase. Although E2 (10(-8) M) did not increase rates of proliferation during the initial logarithmic growth period of the cultures under the chosen experimental conditions (MEM with 15% charcoal-treated fetal bovine serum renewed every 2-3 days), it sustained cell proliferation after about day 10, when parallel control cultures had reached plateau cell densities. Cell proliferation in control cultures at plateau levels was resumed when the hormone was added. Growth rates of cultures containing E2 from the time of seeding and the proportion of quiescent cells, estimated by using a simple cell kinetic model, decreased steadily with time. Ornithine decarboxylase and DNA polymerase alpha activities, as well as estrogen receptor levels, also decreased with time in culture. Ishikawa cells formed colonies in soft agar; colony formation efficiencies were higher as the number of cells seeded was increased from 10,000 to 100,000 cells/6 cm dish, were not influenced by the addition of E2 to the medium (10(-9) to 10(-5) M) and were markedly reduced by difluoromethylornithine (10(-2) M), an effect that was counteracted by putrescine (25 X 10(-6) M).
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PMID:Effects of estradiol on proliferation of endometrial adenocarcinoma cells (Ishikawa line). 380 63

We have evaluated the feasibility of a cytokinetically oriented regimen based on the induction of cell recruitment by diethylstilbestrol (DES) in locally advanced human breast cancer. Tumor proliferative activity was evaluated by the thymidine labeling index and the primer-dependent alpha-DNA polymerase labeling index, which gives an in vitro estimation of the growth fraction. Sixteen previously untreated patients received DES (1 mg daily for 3 days) followed by FAC [5-fluorouracil (600 mg/m2): Adriamycin (50 mg/m2): Cytoxan (600 mg/m2)] i.v. on day 4 every 21 days. Radical surgery was delayed to allow for three DES-FAC regimens in responsive patients. Proliferative activity on tumor biopsies was evaluated immediately before and after treatment with DES, 24 h after chemotherapy and, in nine patients, at the time of radical surgery. DES was able to induce a significant increase in thymidine labeling index in 8 of 16 patients, while the primer-dependent alpha-DNA polymerase labeling index was significantly increased in 13 of 16 tumors, independently of their estrogen receptor content. Subsequently administered chemotherapy induced an early decrease in tumor proliferation. In the nine patients submitted to surgery after three DES plus FAC courses, the average thymidine labeling index and primer-dependent alpha-DNA polymerase labeling index were 27.8 and 73% of the pretreatment values. Our preliminary results provide the rationale for the design of new therapeutic schemes in which antitumor drugs are given at the time of estrogen-induced tumor cell recruitment. Further extended studies are required to establish whether induction of tumor cell recruitment will actually translate into appreciable improvement of the clinical response to chemotherapy.
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PMID:Chemotherapy following estrogen-induced expansion of the growth fraction of human breast cancer. 405 64

The expression of a mouse mammary tumor virus is inducible by hormones, and the virus contains a hormone-responsive element. Viral particles and RNA-directed DNA polymerase (RDDP, EC 2.7.7.7; reverse transcriptase) are both detectable in human breast tumors but the frequency and significance of these findings are unknown. Breast tumor biopsy specimens (from either the primary site or a metastasis), frozen in liquid nitrogen at the time of surgery, were routinely obtained to determine estrogen receptor (ERP) concentration. A sample of the tissue was pulverized, homogenized and centrifuged at low speed to remove nuclei and mitochondria. The supernate was then centrifuged at 225,000 g to obtain the cytosol fraction for estrogen and progestin receptor (PgR) assays. Partially purified membranes for the RDDP assays were prepared from the high-speed pellet by discontinuous sucrose density gradient centrifugation. The RDDP assay involved measuring primer-dependent poly(dT) synthesis in the presence of poly(A) as template and oligo-(dT)12-18 as primer. To date, we have studied biopsy specimens from 46 patients with breast cancer. 27 (59%) had ERP and 23 (50%) were RDDP-positive. There was no significant correlation between ERP concentration and RDDP activity. PgR data were available on 36 of the patients; 17 (47%) were positive. No correlation between RDDP and PgR was apparent. Similarly, there was no correlation between RDDP and clinical stage of the disease.
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PMID:RNA-directed DNA polymerase activity in human breast cancer biopsy specimens. Relation to estrogen receptor protein. 620 38

We have investigated the effects of estrogens and antiestrogens on cellular DNA-dependent DNA polymerase activity in human breast cancer, using as a model the MCF-7 human breast cancer cell line which contains estrogen receptor. 17 beta-Estradiol had little if any effect on cytosol DNA polymerase activity or growth (total DNA per flask) of MCF-7 cells. Incubation of the cells for 4 to 6 days with the antiestrogen nafoxidine, however, resulted in a dose-dependent reduction in cytosol DNA polymerase activity to one-half that observed in untreated cells. Enzyme activity in antiestrogen-treated cells was restored to levels contained in untreated cells by removing antiestrogen from the growth medium and incubating the cells for an additional 4 days with 17 beta-estradiol. The restoration required estrogenic steroids specifically, and the time course, magnitude, and dose dependence of the response were similar to estrogen-stimulated increases in DNA polymerase activity described in other estrogen target tissues. Estrogen-mediated reversal of antiestrogen suppression of DNA polymerase activity was paralleled by increases in total DNA synthesis.
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PMID:Effects of estrogen and antiestrogen on DNA polymerase in human breast cancer. 737 Oct 1

The biological effects of 17 alpha-estradiol (17 alpha-E) and its interaction with estrogen receptors were studied in the MCF-7 human breast cancer cell line. Competition for [3H]17 beta-estradiol ([3H]17 beta-E) binding shows that 17 alpha-E binds to receptor with high affinity and has a dissociation constant (Kd) estimated to be 0.7 nM. Upon binding with 17 alpha-E, the cytosol receptor is translocated to the nucleus and is then rapidly depleted or processed in the same manner as the 17 beta-E-receptor complex. The nuclear 17 alpha-E-receptor complex was determined to be biologically active by its ability to stimulate an increase in the progesterone receptor content and to reverse antiestrogen inhibition of cellular proliferation and DNA polymerase activity. The estrogenic potency of 17 alpha-E, estimated from the dose-response curves as the median effective dose in stimulating progesterone receptor content and in reversing antiestrogen inhibition, is about one tenth the potency of 17 beta-E. Competition curves show that 17 alpha-E binds to the cytosol estrogen receptor with about one third the affinity of 17 beta-E, so the correlation between relative binding affinity and biological potency is not perfect. The correlation, however, is reasonably good compared with that in animal studies, in which 17 alpha-E displays negligible biological activity. Gas chromatography and mass spectrometry rule out the possibility that the observed estrogenic activity of 17 alpha-E was due to contamination of the preparation with the more active 17 beta-E. The enhanced estrogenic potency of 17 alpha-E in MCF-7 cells raises the question of whether the stereospecificity and, thus, the sensitivity of the estrogen receptors in breast cancer cells may be different than those in normal target tissues. Enhanced estrogenic activity may also be due simply to the nature of the tissue culture system, which allows continuous exposure of the cells to hormone; a condition which may not be achieved in some animal studies.
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PMID:17 alpha-Estradiol is a biologically active estrogen in human breast cancer cells in tissue culture. 740 75

Data are presented illustrating the optimum concentration range of reverse transcription PCR-generated products under 500 bp for accurate base calling with direct automated DNA sequencing. A 357-bp fragment of the human estrogen receptor, which includes the DNA binding domain of the protein, was used as a representative example of a gene fragment that can be rapidly amplified and sequenced. Using the Taq DNA polymerase dye terminator sequencing protocol and automated sequencing apparatus from Applied BioSystems, 0.1 to 1.0 pmol of PCR product in a 20-microL reaction volume provided > 97% accurate base detection. Concentrations greater or lower than this range increased the number of ambiguous bases due to alterations in the signal-to-noise ratios. This procedure has been successfully utilized with 140-440-bp PCR products within the optimum concentration range. These results show that low amounts of PCR products are necessary and sufficient for direct sequence analysis.
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PMID:Improved accuracy in direct automated DNA sequencing of small PCR products by optimizing the template concentration. 781

B-cell leukemia/lymphoma (bcl-2) expression can override the apoptosis development in lymphoid and hormonally regulated tissue-like breast. The presence of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR) have revealed in breast carcinomas, but they have not been correlated to the bcl-2 protein expression and DNA fragmentation markers. We evaluated the immunohistochemical expression of bcl-2 protein and hormonal receptors (ER, PR, AR) and differentiation grade in 37 infiltrating ductal carcinomas of the breast for which frozen tissues were available for DNA extraction. The immunohistochemical reaction for bcl-2 was considered positive if more than 50% of neoplastic cells had intense cytoplasmic staining, whereas for steroid receptor evaluation Battifora's criteria were used. The DNA was extracted according to the phenol-chloroform procedure and used for bcl-2 gene rearrangement study of the major breakpoint region (Southern blot) and for membrane-based end-labeling using digoxigenin-labeled nucleotides and E. coli DNA polymerase I (Klenow fragment). The results were quantified by three different observers. Low-grade carcinomas were positive for bcl-2 protein (27/28, 96.4%) and ER (15/28, 53.6%), whereas the remaining neoplasms were negative for bcl-2 (9/9, 100.0%) and ER (8/9, 53.6%) (p < 0.001). No statistically significant differences were revealed at the bcl-2, PR and AR comparisons. The Southern blot analysis for bcl-2 major breakpoint region showed neither rearrangement nor genetic amplification (densitometric study). Only the membrane-based end-labeling of DNA fragments showed correlation with bcl-2 protein and ER expressions: all except one bcl-2-negative tumor and two bcl-2-positive tumors had positive labeling using 7 pg of DNA at dot blot analysis (p < 0.002). The bcl-2 protein expression would allow both proliferation and cell progression by blocking apoptosis in well-differentiated, ER-positive breast carcinomas. In these neoplasms, DNA fragmentation as a molecular marker of apoptosis was prevented by bcl-2 expression.
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PMID:Bcl-2 expression and DNA fragmentation in breast carcinoma, pathologic and steroid hormone receptors correlates. 936 Aug 41


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