Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human mammary carcinoma cells (MCF-7) were arrested in late G1-phase after treatment with agents (forskolin, interleukin-1 beta 3-isobutyl-1-methylxanthine) that increased the endogenous concentrations of cAMP. The effect of elevated cAMP was mimicked by microinjected catalytic (C alpha) cAMP-dependent protein kinase (cAK) subunit and reversed by the injection of a dominant negative cAK regulatory mutant (RID199). Further evidence that activation of cAK induced growth arrest was provided by the use of pairs of stable cAMP analogs known to synergistically activate isolated cAK isozymes. Furthermore, the effect of cAMP was not potentiated by serine/threonine phosphatase inhibitors that profoundly restricted MCF-7 growth. Some 8-substituted cAMP analogs, e.g. 8-Cl-cAMP and 8-NH2-cAMP, induced cell death rather than reversible inhibition of growth. Their effect was not synergized with complementary cAMP analogs. Furthermore, their potency was decreased rather than increased in the presence of an inhibitor of degradation (3-isobutyl-1-methylxanthine). Finally, their effect could be mimicked by degradation products unable to activate cAK. We concluded that 8-Cl-cAMP (and 8-NH2-cAMP) induced irreversible growth arrest by a mechanism not involving cAK, whereas activation of cAK resulted in a transient and fully reversible inhibition of cell proliferation.
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PMID:Cyclic adenosine monophosphate (cAMP) analogs 8-Cl- and 8-NH2-cAMP induce cell death independently of cAMP kinase-mediated inhibition of the G1/S transition in mammary carcinoma cells (MCF-7). 775 Apr 73

Previously we have shown that IGF-I protected MCF-7 cells against death induced by the protein synthesis inhibitor cycloheximide (CHX). In the present study we investigated the ability of protein kinase C activator 12-0-tetradecanoyl-phorbol-13-acetate (TPA), the protein kinase A activator 8-bromoadenosine 3'5'-cyclic monophosphate (Br-cAMP), and the enzyme inhibitor aurintricarboxylic acid (ATA) to protect MCF-7 cells against death, due to a continuous presence of CHX. Cell death was evaluated after 48 h of incubation by several techniques (trypan blue staining, release of lactic dehydrogenase, cellular ATP content, transmission electron microscopy, and DNA fragmentation). Apoptosis which terminates in necrosis, characterized this mode of cell death. TPA and ATA at optimal concentrations of 40 ng/ml and 100 micrograms/ml, respectively, reduced cell death to the control level (without CHX), while Br-cAMP at an optimal concentration of 650 micrograms/ml reduced cell death only partially. IGF-1, TPA, and ATA, which stimulated protein synthesis in the control MCF-7 cells, had no effect on protein synthesis in the CHX-treated cells, indicating that the survival effect is not due to new protein synthesis. The protein kinase C inhibitor staurosporine blocked the survival effect of TPA and IGF-1 in a dose-dependent manner, however did not affect the survival effect of ATA. The tyrosine kinase inhibitor genistein blocked the survival effect of IGF-1, but not that of TPA and ATA. Our results provide evidence for several distinctive pathways, the activation of which protects MCF-7 cells against death, due to protein synthesis inhibition.
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PMID:Multiple pathways are involved in protection of MCF-7 cells against death due to protein synthesis inhibition. 777 99

Serine 167 has been identified by radiolabel and amino acid sequencing as the major estrogen-induced phosphorylation site on the human estrogen receptor (hER) from human MCF-7 mammary carcinoma cells. The phosphorylation of the hER on serine 167 was estrogen-dependent, increasing 4-fold upon estradiol treatment of MCF-7 cells and accounted for almost half of the total [32P]phosphate incorporated into the recombinant hER from Sf9 insect cells and the native hER from MCF-7 cells. Casein kinase II was found to phosphorylate the purified recombinant hER on serine 167 in vitro. In addition, estradiol binding enhanced by 2-fold the phosphorylation of the purified recombinant hER by casein kinase II in vitro. Western blot analysis and [32P]phosphate incorporation confirmed the presence of casein kinase II in Sf9 cells. These results demonstrate that the hER is phosphorylated on serine 167 by casein kinase II in a hormone-dependent manner.
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PMID:Serine 167 is the major estradiol-induced phosphorylation site on the human estrogen receptor. 783 53

We report here that the human estrogen receptor (hER) overexpressed in Sf9 insect cells is phosphorylated similarly to hER from the human MCF-7 mammary carcinoma cell line. The recombinant and native hER labeled to steady-state with [32P]phosphate were purified to homogeneity using specific DNA-affinity chromatography followed by SDS-gel electrophoresis. Resolution of the hER tryptic digests by reverse phase-high performance liquid chromatography revealed that five [32P]phosphopeptides from the hER expressed in the Sf9 cells had retention times identical to five of the seven [32P]phosphopeptides from the hER in MCF-7 cells. Uniquely, a dephosphorylation of a single 32P-labeled peptide occurred in response to estradiol treatment of MCF-7 cells. In vitro protein kinase assays with the purified recombinant hER revealed that the DNA-dependent protein kinase (DNA-PK) phosphorylated the receptor and induced a decrease in the receptor's mobility as demonstrated by SDS-gel electrophoresis. In contrast, protein kinases A and C did not phosphorylate the purified recombinant hER. These results suggest that in the process of becoming transcriptionally active the estrogen receptor undergoes a dephosphorylation after estrogen-binding and subsequent phosphorylations, in part by the DNA-PK.
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PMID:In vivo and in vitro phosphorylation of the human estrogen receptor. 787 51

MCF-10A, a nontransformed mammary epithelial cell line, requires a mixture of hormones and growth factors for optimal cell proliferation. In this report we show that when MCF-10A cells are cultured in serum free medium they become quiescent and accumulate in G0/G1 phases of the cell cycle. Following addition of complete medium to quiescent cells, MCF-10A cells enter into the S phase within 15-18 h and resume the cell cycle distribution of proliferating cells within 24 h. Measurement of RI alpha subunit of the cAMP-dependent protein kinase (PKA) shows a 10- to 15-fold increase in protein levels at 6 h following complete medium addition, thus preceding cell entry into the S phase. Retroviral vector-mediated overexpression of RI alpha, but not of RII beta or C alpha subunits of PKA, enables MCF-10A cells to grow in serum-free medium. In addition, RI alpha downregulation by specific antisense oligodeoxynucleotide treatment or following infection with a retroviral vector containing the RI alpha cDNA in antisense orientation determines growth arrest of proliferating MCF-10A cells and is able to partially block S phase entry of quiescent MCF-10A cells following complete medium addition. These results suggest that RI alpha/PKAI is involved in the control of cell cycle progression of mammary epithelial cells at a G1 to S transition border, and that its overexpression is able to overcome serum and growth factors requirement for cell proliferation.
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PMID:The RI alpha subunit of protein kinase A controls serum dependency and entry into cell cycle of human mammary epithelial cells. 793 47

Tumor necrosis factor (TNF) has been shown to bind two distinct receptors, designated p60 and p80, with high affinity, resulting, within minutes, in phosphorylation of several proteins. The receptors themselves do not exhibit protein kinase activity nor have any associated proteins been identified. We employed the glutathione-S-transferase (GST) fusion protein system consisting of the cytoplasmic domain of p60 (GST-p60CD delta 1) as a probe to help us identify receptor-associated proteins from human histiocytic lymphoma U-937 cells. We found that a protein of approximately 52 kDa (pp52) bound to GST-p60CD delta 1 from [35S]methionine- and 32P-labeled cells. The associated protein was phosphorylated on serine and threonine residues. Furthermore, we identified serine/threonine kinase activity associated with p60CD delta 1 that required either Mn2+ or Mg2+ for optimal activity. The preferred substrates for this kinase, in addition to p60CD delta 1, included casein and histone H1, but not histone H2B, myelin basic protein, enolase, or the cytoplasmic domain of p80. As was the case in U-937 cells, p60CD delta 1-associated kinase activity was also identified in human breast adenocarcinoma MCF-7 cells and human foreskin fibroblasts. TNF stimulation of MCF-7 and foreskin fibroblasts for 5-15 min induced approximately 50 and 240% increases in phosphorylation of p60CD delta 1, respectively. Thus, our results provide the first evidence for protein kinase activity that is specifically associated with the cytoplasmic domain of the p60 form of the TNF receptor and causes its phosphorylation. This p60 TNF receptor-associated protein and the associated kinase described here are referred to as p60-TRAP and p60-TRAK, respectively.
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PMID:Identification of a protein kinase associated with the cytoplasmic domain of the p60 tumor necrosis factor receptor. 805 Nov 24

MCF-10A is a spontaneously immortalized, non-transformed human mammary epithelial cell line. We have recently obtained MCF-10A clones (MCF-10A HE cells) that are transformed following over-expression of both a human point-mutated c-Ha-ras and the c-erbB-2 proto-oncogenes. Two isoforms of the cAMP-dependent protein kinase (cAK) have been described in mammalian cells. Enhanced levels of type-I cAK (cAKI) are generally found in tumor cells. To determine whether inhibition of cAKI expression may interfere with ras and erbB-2 oncogene-induced transformation of human mammary epithelial cells, we have tested the effects of 2 agents that specifically down-regulate cAKI, such as 8-chloro-cAMP and an anti-sense oligodeoxynucleotide targeted against the RI alpha regulatory subunit of cAKI on MCF-10A HE cells. Treatment of MCF-10A HE cells with 8-chloro-cAMP induces a dose-dependent growth inhibition under both monolayer and soft-agar growth conditions, that is correlated with an accumulation of MCF-10A HE cells in G0/G1 phases of the cell cycle and a reduction of the number of cells in S phase. In contrast, 8-chloro-cAMP has no effect on MCF-10A cell growth. Furthermore, 8-chloro-cAMP treatment of MCF-10A HE cells induces a 4- to 6-fold reduction in p185erbB-2 expression and brings p21ras expression to levels comparable to those found in MCF-10A cells. Treatment of MCF-10A HE cells with an RI alpha anti-sense oligodeoxynucleotide determines a comparable inhibition of both anchorage-dependent and anchorage-independent cell growth. Our results suggest that cAKI may act as a mediator of ras and erbB-2 oncogene action in human breast cells and that interference with cAKI action provides a potential tool for inhibiting the growth-promoting effects of these oncogenes.
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PMID:Down-regulation of RI alpha subunit of cAMP-dependent protein kinase induces growth inhibition of human mammary epithelial cells transformed by c-Ha-ras and c-erbB-2 proto-oncogenes. 809 73

We have characterized regulation of type-1 plasminogen activator inhibitor (PAI-1) gene expression by phorbol 12-myristate 13-acetate (PMA) and the cAMP-inducing agent forskolin in the human breast carcinoma cell line MCF-7. PMA caused a strong induction of PAI-1, while forskolin suppressed the PMA response. Transfection experiments with fusion genes showed that sequences mediating PMA induction as well as forskolin suppression were present between base pairs -100 and -30 of the 5'-flanking region of the PAI-1 gene. The region was found to contain two Sp1 binding sites. A proximal sequence in the region, TGAGTTCA (P box), with sequence similarity to phorbol ester response elements (TRE) as well as to cAMP response elements (CRE), bound a low-abundance, as yet unidentified nuclear protein in MCF-7 cells. This sequence had a higher affinity to purified c-jun homodimer than to c-jun/c-fos heterodimer in MCF-7 nuclear extracts; it had no affinity to the proteins binding to CRE consensus sequences in these extracts. A distal TRE-like sequence, TGAGTGG (D box), had a weak affinity to c-jun/c-fos heterodimer and c-jun homodimer; binding of proteins to this sequence was facilitated by binding of proteins to the P box. Both the P box and the D box were necessary for PMA responsiveness, suggesting a cooperativity between the two binding sites. A mutation of the P box removing the CRE similarity abolished the forskolin suppression of the PMA response. We propose that the protein kinase C and the protein kinase A signal-transduction pathways, with opposite effects on PAI-1 gene expression converge by modulating differently P-box-binding proteins.
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PMID:A common response element mediates differential effects of phorbol esters and forskolin on type-1 plasminogen activator inhibitor gene expression in human breast carcinoma cells. 811 99

The possible involvement of PKC in the regulation of heat shock genes expression was investigated with three isoquinolinesulfonamide derivatives (H-7, H-8, and HA1004) in DUT-145, MCF-7, and MCF-7/ADR cells. The drug was added 1 hr before and during heating at 41 degrees C. Northern blots show that the levels of HSP70 and HSP28 mRNA increased rapidly and reached maximal values within 4-8 hr and 8-12 hr, respectively. H-7 and H-8 which are potent PKC inhibitors selectively suppressed the accumulation of HSP70 mRNA as well as the synthesis of HSP70. In contrast, HA1004 which is a potent PKA inhibitor but a weak PKC inhibitor did not affect HSP70 gene expression. These results suggest that PKC rather than PKA plays an important role in the regulation of heat shock gene expression.
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PMID:Effect of isoquinolinesulfonamides on heat shock gene expression during heating at 41 degrees C in human carcinoma cell lines. 813 14

cAMP-dependent protein kinase (PKA) is composed of two genetically distinct catalytic (C) and regulatory (R) subunits. There are two different classes of PKA, designated as type I and type II, which contain distinct R subunits (RI or RII, respectively) but share a common C subunit. Enhanced expression of type I PKA has been correlated with cell proliferation and neoplastic transformation. Detection of the different PKA subunits is usually performed by photoaffinity labeling with 8-N3-32P-cAMP or by radioimmunolabeling techniques. Both techniques are time consuming and require a high number of cells and the use of radioactive reagents. Using the MCF-10A normal human mammary cell line infected with a recombinant retroviral vector containing the human RI alpha gene (MCF-10A RI alpha), we have developed a flow-cytometric assay to detect the intracellular content of RI alpha protein in human cells. MCF-10A and MCF-10A RI alpha cells were fixed in 1.5% paraformaldehyde at 37 degrees C for 15 min and permeabilized by methanol and acetone (1:1) at -20 degrees C for 5 min before staining with a specific IgG2a MoAb followed by a FITC-conjugate rabbit-anti mouse IgG. This procedure was also successfully utilized to recognize RI alpha protein content in human peripheral blood lymphocytes. Flow-cytometric detection of the RI alpha subunit in human cells is feasible and allows the study of the role of type I PKA in cell growth and neoplastic transformation.
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PMID:Flow-cytometric detection of the RI alpha subunit of type I cAMP-dependent protein kinase in human cells. 816 27


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