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:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MCF-7, a continuous cell line derived from a human breast carcinoma, exhibits very low alkaline phosphatase (ALP) activity. The enzyme is heat-stable and is inhibited by L-phenylalanine and L-phenylalanylglycylglycine, but not by L-homoarginine, 1-bromotetramisole, or levamisole. These data indicate that MCF-7 produces term-placental ALP, the oncodevelopmental enzyme form inappropriately expressed by a variety of human tumors. In contrast to human cancer cells that produce this enzyme monophenotypically, ALP activity of MCF-7 cells is not significantly increased by glucocorticoids or sodium butyrate. By comparison, exposure to hyperosmolality causes a striking increase in enzyme activity. Cycloheximide blocks this effect. The results obtained with cell-free assays were confirmed by cytochemical and immunocytochemical assays on whole cells. Because some of the agents tested in the enzyme modulation experiments affect cell proliferation, their possible effect on two stress-response proteins (srp 27 and srp 72) was also examined; specific immunocytochemical assays were used. These tests revealed that neither protein is affected by glucocorticoids; that sodium butyrate has no effect on srp 27, but alters the intracellular distribution of srp 72; and that hyperosmolality, while not significantly affecting srp 72, causes an increase in srp 27.
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PMID:Effect of hyperosmolality on alkaline phosphatase and stress-response protein 27 of MCF-7 breast cancer cells. 146 64

We have previously shown that occult micrometastases can be detected in the bone marrow of breast cancer patients, at the time of initial treatment, using a panel of epithelial specific monoclonal antibodies indirectly labeled with fluorescein. These monoclonal antibodies permit us to detect cancer cells at at concentration of two/million normal bone marrow cells. Immunofluorescence carries the disadvantage that detailed morphological examination of detected cells cannot be accomplished. A modification of the alkaline phosphatase anti-alkaline phosphatase method has been used to detect cancer cells and to observe their morphology in human bone marrow. The sensitivity of this method has been examined using an established human metastatic breast cancer cell line (MCF-7) mixed with normal bone marrow cells at various dilutions from 400 cancer cells/10(6) marrow cells to 10 cancer cells/10(6) marrow cells. The number of immunocytochemically stained MCF-7 cells counted at each concentration was related to the concentration by a simple nonlinear statistical model. At a concentration of 10 cancer cells/10(6) bone marrow cells, the model shows that this method has the sensitivity to detect between four and six MCF-7 cells 95% of the time. Extrapolation, using this model, predicts that at the very low concentration of one cancer cell/10(6) marrow cells, there is a 95% chance of detecting the cancer cell. This assay may be a very sensitive method for detecting cancer cells in the bone marrow of breast cancer patients.
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PMID:Sensitivity of immunocytochemical detection of breast cancer cells in human bone marrow. 202 49

Biochemical and molecular biological studies of osteoblastic cell function and hormonal regulation are frequently confounded by the inherent cellular heterogeneity and phenotypic instability of existing in vitro and in vivo model systems. A new technique (derived from Western blotting or antibody-based detection of protein molecules bound to nitrocellulose paper) is described for identification of individual cells which synthesize osteoblast-specific gene products (bone Gla-protein, type I collagen, and alkaline phosphatase) or produce cAMP in response to parathyroid hormone (PTH) or isoproterenol. Dispersed primary neonatal rat calvariae or osteogenic sarcoma cells were "plated" on Immobilon-P (a hydrophobic transfer membrane with very high protein-binding capacity) for 30 minutes to several hours, followed by agonist treatment, formalin fixation, hematoxylin staining, and immunostaining with a battery of antibodies specific for osteoblastic products. Individual cells and their secretory zones were visualized by light microscopy and counted. Treatment with PTH with or without isoproterenol resulted in increases in the percentages of osteoblastic cells elaborating cAMP, as well as the intensity of immunostaining, but had no effects on MCF-7 cells, a nonosteoblastic breast carcinoma control line. The percentage of cells within each primary osteoblastic cell population isolated or rat osteogenic sarcoma cell clone (G2 or C12) that elaborated bone-specific proteins or that generated cAMP in response to PTH varied with time and the individual cellular preparation, reconfirming the cellular heterogeneity of these systems. This method, in conjunction with techniques such as in vitro hybridization, should prove useful in characterizing discrete osteoblastic bone cell subpopulations and in clarifying mechanisms of hormonal regulation by local and systemic agents.
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PMID:Rapid, simple identification of individual osteoblastic cells and their specific products by cell blotting assay. 255 3

The effect of the nucleoside anti-metabolite tiazofurin (TR) was examined on the growth and phenotypic alterations of MCF-7 breast cancer and HBL-100 normal breast cell lines. TR was shown to inhibit MCF-7 cell growth. This inhibition could be reversed by exogenous addition of guanosine. The anti-proliferative effect of TR is accompanied by phenotypic alterations that include lipid accumulation and an increase in alkaline phosphatase activity. In contrast to MCF-7 cells, the HBL-100 breast milk derived cell line is relatively resistant to inhibition by TR. Alkaline phosphatase is not affected by TR and untreated cells accumulate lipid droplets, similar to TR-treated MCF-7 cells. Determination of GTP and ATP pools in both cell lines revealed that TR markedly reduces GTP content in MCF-7 cells. In HBL-100 cells, TR induces only a small decrease in GTP and does not affect ATP levels. The prototypic IMP dehydrogenase inhibitor, mycophenolic acid (MA), markedly inhibits HBL-100 cell growth, similarly to its effect on MCF-7 breast cancer cells. These findings may suggest differential metabolism of TR in MCF-7 and HBL-100 cells.
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PMID:Growth inhibition and induction of phenotypic alterations by tiazofurin: differential effects on MCF-7 breast cancer and HBL-100 breast cell lines. 273 21

The activity of the enzyme ornithine decarboxylase (ODC) is increased in confluent culture of two breast cancer cell lines (T47D and MCF-7) following a change of medium. The increase in activity is maximum at 12 hours and this level is reduced in cells treated with high concentrations of HuIFN-alpha. However, the increased level of ODC activity seen in the first few hours after medium change can be stimulated by low concentrations of interferon (10-100 units per ml). The activity of the acidic and alkaline phosphatase of the above cell lines are affected by HuIFN-alpha similar to ODC. In stimulating levels of ODC and phosphatases, interferon is acting similar to mitogens, and in T47D and MCF-7 cells this stimulatory effect precedes the inhibitory effect more commonly seen in interferon-treated cells.
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PMID:Ornithine decarboxylase and phosphatase activity can be stimulated by low concentrations of interferon in human breast cancer cell lines. 285 Oct 88

Sodium butyrate and dimethylsulfoxide (DMSO), two known chemical inducers of cell differentiation, were examined on MCF-7 breast cancer cells. Both agents reduce the proliferative capacity of MCF-7 cells, as reflected by inhibition of colony formation in semisolid agar. Sodium butyrate is shown to enhance markedly the activity of two plasma membrane-bound enzymes, alkaline phosphatase and gamma-glutamyl transpeptidase. DMSO does not enhance the activity of these enzymes, but rather induces a small decrease in gamma-glutamyl transpeptidase activity. The present results show that although both agents inhibit cell proliferation, they have a distinct effect on phenotypic expression.
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PMID:Differential effects of sodium butyrate and dimethylsulfoxide on gamma-glutamyl transpeptidase and alkaline phosphatase activities in MCF-7 breast cancer cells. 289 May 41

Bone metastases of breast cancers produce not only osteolytic but also osteosclerotic lesions. The latter are often observed after androgenic treatment of the tumor. Potential production of osteoblast stimulating activity (ObSA) in breast cancer cell lines, and possible androgen control of this activity have been investigated. Conditioned media (CM) collected from 4 breast cancer cell lines (MCF-7, ZR75, MDA-MB 231, BT20) was tested in vitro on ROS 17/2,8 osteoblast-like cells and on osteoblasts derived from human bone biopsies. The parameters monitored in osteoblasts were [3H]thymidine incorporation, alkaline phosphatase activity, and osteocalcin secretion. Serum-free media conditioned during 24 h by MCF-7 cells presented the highest ObSA. CM decreased thymidine incorporation in DNA and increased alkaline phosphatase activity in a dose-dependent manner. Bone GLA protein (osteocalcin) secretion by human osteoblasts was not increased however in the presence of CM. MCF-7 cells were cultured in the presence of dihydrotestosterone (DHT) [1-100 nM] for 5 days. Serum-free, DHT-free CM collected after an additional 24 h, contained alkaline-phosphatase stimulating activity which was DHT dose-dependent. Estradiol and 1,25(OH)2D3 failed to elicit a comparable increase of the ObSA in the CM. In conclusion, MCF-7 cells product factor(s) that interfere with bone remodeling. The DHT modulation of ObSA parallels the estradiol control of MCF-7 cells osteolytic lesions in relation with Prostaglandin E secretion. Sex hormones at physiological and pharmacological levels might thus control both osteosclerotic and osteolytic lesions observed in bone deposits of hormone dependent cancers.
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PMID:Androgens increase osteoblast-stimulating activity of human breast cancer cells in vitro. 370 24

Isozyme patterns of 23 different enzymes were compared in normal, benign, and malignant breast tissues; in MCF-7 cells; and in organoids of normal human breast tissue. Benign lesions generally showed isozyme patterns similar to those of normal tissues. Lactate dehydrogenase isozyme 5 was significantly increased in malignant tumors; MCF-7 cells had only lactate dehydrogenase (L-lactate:NAD oxidoreductase; EC 1.1.1.27). The mitochondrial form of malate dehydrogenase was also significantly increased in human malignant tumors; this was especially evident when comparing tumor and apparently uninvolved breast tissue from the same patient. The K4 isozyme of pyruvate kinase was the major form in most malignant breast tumors, but in only 41% of normal tissues, 30% of fibrocystic disease specimens, and 46% of fibroadenomas. A more anodal band of pyruvate kinase, probably a K3M or K3Kpm hybrid, predominated in most normal and benign tissues, but in only 63% of primary and 56% of secondary tumors. All specimens had predominantly creatine kinase BB, aldolase A4, and hexokinase I. Traces of aldolase A3C and of hexokinase II were observed in some tumors. None of the tumors had the Regan variant of alkaline phosphatase. The isozymes of lactate and malate dehydrogenases and of pyruvate kinase appear to be the most promising as putative tumor markers.
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PMID:Isozyme patterns of normal, benign, and malignant human breast tissues. 664 May 38

Although 17 beta-estradiol (E2) replacement therapy has been shown to be effective in treating postmenopausal osteoporosis, the underlying mechanism remains unclear. The presence of low levels of functional endogenous estrogen receptor (ER) in some osteoblastic cells has been demonstrated, and the suggestion that the abundance of ER may be rate-limiting in the action of E2 on these cells has been made. To study the mechanism of ER in regard to E2-mediated effects, we stably transfected a human osteosarcoma cell line, SaOS-2, with an expression vector, pMV-7-ER, containing the human ER gene. We characterized six of the stably transfected clones. One of the stable clones, SaOS-2-ER, expressed extra copies of ER genes integrated into the genome as detected by Southern blot analysis, showed a significantly increased level of ER mRNA by RT-PCR, and contained an increased level of ER cytosolic protein as detected by an ER-specific EIA. The overexpressed ER was functional and sensitive to E2 in a dose-dependent fashion after transient transfection with a vector containing an estrogen response element (ERE) linked to a chloramphenicol acetyltransferase (CAT) reporter gene. Scatchard analysis revealed a single high-affinity binding site with a Kd similar to values obtained for the ER in MCF-7 breast cancer cells. These SaOS-2-ER cells had altered osteoblast phenotypic features including growth inhibition, decreased basal alkaline phosphatase activity, and decreased IL-6 expression and secretion. In response to E2, a greater than 2-fold increase in TGF-beta 1 mRNA was quantitatively measured in these ER-overexpressing osteoblasts. These cells may provide a sensitive and unique model for understanding the mechanism of E2 and ER in overall bone metabolism.
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PMID:Generation and characterization of a human osteosarcoma cell line stably transfected with the human estrogen receptor gene. 763 12

Cytospins of a human breast cancer cell line (MCF-7) were studied for the expression of PCNA, a cell cycle-related protein, using a variety of fixation and immunostaining procedures. The best fixative for PCNA was found to be buffered formaldehyde solution at 4 degrees C followed by methanol at 20 degrees C, whereas alcoholic fixatives decreased greatly the PCNA immunoreactivity. Air-drying procedures of cytospins prior to and after fixation greatly undermined the PCNA immunostaining. A modified immunoperoxidase method provided a stronger staining of the PCNA-reactive cells than the alkaline phosphatase anti-alkaline phosphatase (APAAP) technique. PCNA immunoreactivity could be maintained up to 2 mo, putting slides in methanol at -20 degrees C. In conclusion, our report indicates that PCNA is a labile antigen, which may critically be affected by temperature and air-drying procedures.
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PMID:Methodological aspects of the immunostaining of proliferating cell nuclear antigen (PCNA) in cytospin preparations of MCF-7 cell line. 791 57


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