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)

The effects of estradiol on DNA polymerase alpha activity were investigated in an estrogen-responsive human endometrial cancer cell line (Ishikawa) derived from a well differentiated endometrial adenocarcinoma. These cells are known to respond to estradiol by increasing progesterone receptor levels, alkaline phosphatase activity, and cell density. Four- to 5-fold increases in DNA polymerase alpha activity occurred when estradiol was added to cultures of Ishikawa cells in medium containing charcoal-treated fetal bovine serum. Maximal stimulation was achieved at 18 h during incubations with 10(-8) M estradiol, but significant effects also were found with 10(-9) and 10(-6) M. These effects were almost completely counteracted by a 100-fold excess of 4-hydroxytamoxifen. At 10(-6) M, the antiestrogen had no influence on the basal levels of DNA polymerase alpha. Medroxyprogesterone acetate (10(-6) M) was ineffective as either an enhancer of enzymatic activity or an antiestrogen when tested in combination with 10(-8) M estradiol, even in the presence of appreciable levels of specific progesterone binders. The responsiveness of the Ishikawa cells to estrogen contrasts with the lack of effects of estradiol on DNA polymerase alpha activity in another human endometrial adenocarcinoma cell line (HEC-50).
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PMID:Effects of estradiol on deoxyribonucleic acid polymerase alpha activity in the Ishikawa human endometrial adenocarcinoma cell line. 294 47

By statistical study on 135 patients with endometrial carcinoma, it is clarified that the most effective prognostic factor of the cancer is the histological grading. Well differentiated type is best prognostic and possesses hormone receptors. Application of cell culture is one of the most suitable choices in the study of hormone and human endometrial carcinoma. Present paper is to show usefulness of in vitro study by taking example of the above theme. 1) Binding ability of endometrial carcinoma cells to estrogen: Being explained by Gurpide et al. by using HEC-1 cells, the ability is under control of cGMP and cAMP ratio. 2) Responses to estrogen: DNA polymerase alfa of Ishikawa cells which possesses both estrogen and progesterone receptors (ER, PR) is stimulated first showing peak at 18 hours and alkaline phosphatase (ALP) is at 72 hours by E(2)10(-8)M, which is antagonized by OH-tamoxifen. PR level is also enhanced at its maximum after 3 day E2 treatment, and is analyzed by immunocytochemistry with PR mono-clonal antibody as well as biochemical assay. Gorski and Greene's theory that steroid receptor is localized in nuclei is confirmed in endometrial carcinoma. Growth of Ishikawa cells is apparently enhanced in the aspects of shortened cell cycle and unlimited saturation density. 3) Responses to progestogen: Nucleic acid syntheses of HEC-1 are immediately suppressed by progesterone (P) 2.5 microg or more. Electron microscopic findings show appearances of Golgi apparatus and lysosomal granules. Growth suppression is observed in the cell lines regardless of PR positivity. ALP activity of PR-negative HEC-50 cells
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PMID:[Cell culture--its application in the study of hormone and endometrial carcinoma and feed-back to clinical medicine]. 315 Aug 47

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