Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Modulation of doxorubicin (DOX) cytotoxicity by the calmodulin inhibitor trifluoperazine (TFP) in progressively doxorubicin-resistant L1210 mouse leukemia cells is unrelated to effects on drug accumulation. Based on the clastogenic activity of DOX, the effects of TFP and the selective calmodulin inhibitor 1,3-dihydro-1-[1-[4-methyl-4H,6H-pyrrolo[1,2-a][4,1]- benzoxazepin-4-yl-methyl]-4-piperidinyl]-2H-benzimidazol-2-o ne(1:1) maleate (CGS9343B) on DOX-induced chromosomal damage and its relationship to cytotoxicity were evaluated in sensitive and progressively DOX-resistant L1210 cells. Potentiation of DOX cytotoxicity by CGS9343B (a potent inhibitor of calmodulin which does not inhibit protein kinase C) was related to the level of resistance. Further, for equivalent cytotoxicity, cellular DOX levels in the absence versus the presence of TFP or CGS9343B were markedly higher. Exposure to calmodulin inhibitors following DOX treatment enhanced chromosomal aberrations and cytotoxicity. Maximal effects of calmodulin inhibitors were apparent when used during and after DOX treatment, and potentiation of cytotoxicity was related to modulation of DOX-induced chromosomal aberrations. Results suggest that inhibition of calmodulin-regulated processes is a potential target in the modulation of DNA damage/repair, and could play a pivotal role in the expression of "acquired resistance" to DOX.
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PMID:Modulation of doxorubicin-induced chromosomal damage by calmodulin inhibitors and its relationship to cytotoxicity in progressively doxorubicin-resistant tumor cells. 222 19

Bryostatin 1, a macrocyclic lactone isolated from the marine bryozoan Bugula neritina, has demonstrated both antineoplastic activity against the murine P388 leukemia line in vivo and stimulatory activity against mouse and human hematopoietic progenitors. We studied the effects of bryostatin 1 on the growth of human leukemias in vitro. Bryostatin 1 inhibited 1 to 4 logs of clonogenic leukemia cell growth from three of four leukemia cell lines. Bryostatin 1 also inhibited, by at least 1 log, the proliferation of clonogenic acute nonlymphocytic leukemia (ANLL) cells from 10 to 12 patients with newly diagnosed or relapsed ANLL. Maximal inhibition of leukemic growth occurred at 10(-9) to 10(-7) mol/L bryostatin 1. Interestingly, bryostatin 1 also inhibited the growth of hematopoietic progenitors from eight patients with myelodysplastic syndromes (MDS). Leukemia cells exposed to bryostatin 1 for up to 96 hours and then washed, demonstrated no substantial inhibition of clonogenic growth, indicating that the anti-leukemic effect of bryostatin 1 is cytostatic. The phorbol ester 12-0-tetradecanoylphorbol-13-acetate (TPA) produced more potent inhibition of clonogenic leukemia growth, and this inhibition was blocked by bryostatin 1. Thus, the anti-leukemic activity of bryostatin 1 may be mediated through activation of protein kinase C. Bryostatin 1 inhibits clonogenic leukemia cells at concentrations that stimulate normal hematopoietic progenitors. The differential effects of bryostatin 1 on normal and abnormal hematopoiesis suggest that bryostatin 1 may have value in the treatment of leukemias and MDS.
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PMID:Bryostatin 1, a unique biologic response modifier: anti-leukemic activity in vitro. 231 Aug 30

We have tested a panel of recombinant hematopoietic growth factors (HGF) including the interleukins (IL) 1, 2, 3, 4, and 6 and the colony stimulating factors GM-CSF, G-CSF, M-CSF for their ability to induce proliferation of precursor B acute lymphoblastic leukemia cells (ALL) from 19 patients. In Ficoll-Isopaque isolated and T cell-depleted ALL bone marrow samples, IL2 (two cases), IL3 (four cases), and GM-CSF (one case) infrequently stimulated DNA synthesis measured by 3H-thymidine (TdR) uptake, and the other recombinant growth factors completely failed to do so. In repeat experiments with ALL blasts purified by fluorescence activated cell sorting (FACS), IL2, IL3, and GM-CSF responses could not be reproduced, suggesting that nonleukemic contaminant cells, and not the ALL blasts, had been stimulated by these factors. Cocktails containing combinations of IL1-IL4 and IL6 also lacked proliferation inducing potency. Depending on the purity of the incubated ALL cell samples, an impure preparation of B cell growth factors that has been reported to contain a highly effective stimulatory activity for precursor B ALL cells induced proliferation of residual normal cells as well as the ALL cells, as was evident from combined analysis of DNA synthesis and karyotyping. Exposure of the ALL blasts to artificial activators of protein kinase C and Ca2+ mobilization resulted in significant rises in 3H-TdR uptake, suggesting that these intracellular compounds are involved in transducing signals that upregulate proliferation. Although it remains possible that some of the human recombinant growth factors promote the growth of precursor B ALL cells in combination with other stimuli, a dominant role in the regulation of proliferation of these cells cannot be attributed to any of these cytokines at the present time.
Leukemia 1989 May
PMID:Recombinant hematopoietic growth factors fail to induce a proliferative response in precursor B acute lymphoblastic leukemia. 249 81

Signals from many receptor-ligand interactions are mediated by enhancement of phospholipid hydrolysis which generates metabolic intermediates stimulating protein kinase C (PKC) and elevating cellular calcium. Pharmacologic agents such as phorbol 12, 13-dibutyrate (PDBu) and ionomycin selectively stimulate PKC and elevate intracellular calcium to directly stimulate downstream mechanisms critical to cell growth and function. This study examines the effects of PDBu, ionomycin, and rIL-2 on childhood ALL blasts of early B lineage with respect to various aspects of cell activation, including DNA synthesis, induction of non-MHC restricted tumoricidal activity, and changes in morphology and phenotype. Five childhood ALL samples were tested. A marked heterogeneity was seen among the ALL samples with respect to in vitro growth following manipulation with PDBu, ionomycin, and/or rIL-2, whereas normal peripheral blood lymphocytes (PBL) were consistently stimulated to grow with the combination of PDBu and ionomycin. Growth responsiveness did not appear to correlate with morphologic or phenotypic classification of the leukemia samples. Four of the five leukemia samples developed substantial non-MHC restricted cytotoxicity to K562 (natural killer cell (NK) sensitive) and Daudi (NK resistant) targets in response to rIL-2. This functional cytotoxic response correlated with morphologic changes in the cells and the appearance of granules. Phenotypic analyses of the ALL samples at the time of their peak cytotoxic function were consistent with the fresh ALL phenotype and showed no major change in cell populations. Three of the five ALL samples also retained rIL-2 induced cytotoxic capabilities when exposed simultaneously to the combination of PDBu and ionomycin, whereas rIL-2 induced tumoricidal activity in normal PBL and bone marrow cultures was inhibited by these reagents. These data show that morphologically and phenotypically similar ALL blasts have heterogeneous proliferative responses to the PKC and calcium modulators PDBu and ionomycin, as well as to rIL-2. Cytotoxic responses are also different from those of normal PBL and bone marrow cells with respect to kinetics and responsiveness to inducing agents. Thus current morphologic and phenotypic classifications of ALL may not adequately reflect the heterogeneity of this disorder as described here.
Leukemia 1989 Aug
PMID:Induction of tumoricidal activity and alterations of growth by interleukin-2 and manipulation of protein kinase C and cytosolic calcium in childhood acute lymphocytic leukemia cells. 278 55

Bryostatin 5 is a macrocyclic lactone which activates protein kinase C (PKC). PKC activation has been implicated in leukemic cell differentiation. We have examined the effect of PKC activation by bryostatin 5 on human acute myeloid cell differentiation in the presence and absence of vitamin D3. In vitro treatment of 20 patient samples of acute myeloid leukemias in a 4 days culture system with 10 nM bryostatin 5 induced strongly adherent macrophage-like cells in all cases. Bryostatin 5 induced a significant (p = 0.00006) increment in esterase activity in a majority of the samples, which was further enhanced by vitamin D3. CD14 expression was significantly (p = 0.035) enhanced with the combination of bryostatin 5 and vitamin D3. Nitroblue tetrazolium (NBT) reducing ability was, however, nearly abolished (p = 0.0007). A loss of CD34 expression occurred during cell culture; this loss was enhanced by vitamin D3, but prevented partly by bryostatin 5. Together these findings indicate that exposure to bryostatin 5 leads to a strong macrophage-like cell differentiation in human myeloid leukemia and that VD3 has an additional effect. These findings strengthen the potential role of bryostatins as possible antileukemic agents.
Leukemia 1994 Feb
PMID:The differentiation inducing effect of bryostatin 5 on human myeloid blast cells is potentiated by vitamin D3. 750 34

Incubation of B chronic lymphocytic leukemia (B-CLL) cells with phorbol esters resulted in the phosphorylation of three Triton-soluble, heat-stable, acidic proteins with apparent M(r) of 80 KDa, 60 KDa and 43 KDa. The characteristics of the three proteins suggested that they could be related to the myristoylated, alanine-rich, C-kinase substrate (MARCKS). p80 was immunoprecipitated with an antibody against the N-terminal peptide of MARCKS. p43 co-migrated with mouse MRP/Mac-MARCKS (MARCKS-related protein). p60 is the most prominent substrate of protein kinase C in B-CLL cells.
Leukemia 1995 May
PMID:Phosphorylation of the MARCKS family of protein kinase C substrates in human B chronic lymphocytic leukemia cells. 776 46

The human leukemic cell line NB4 was derived from a patient with acute promyelocytic leukemia and is characterized by a specific 15;17 chromosomal translocation. We analyzed the response of NB4 and HL-60 cells to the biomodulators all-transretinoic acid (ATRA), vitamin D3 (Vit D3) and the protein kinase C agonists bryostatin 1 (Bryo 1) and phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). HL-60 cells were used for comparison being arrested at the myeloblastic-promyelocytic stage, but lacking the t(15;17) abnormality. In most experiments Vit D3 was only weakly or not at all effective. The other three reagents effectively slowed or stopped the proliferation of the cells in suspension. Associated with this proliferation arrest was the cell differentiation along the myeloid cell lineages: ATRA modulated morphological features indicative of granulocytic differentiation; Bryo 1 and TPA caused also distinct morphological changes. The inducers up-regulated the expression of CD11b (without changing the surface expression of other markers, e.g. CD13, CD14, CD15, CD33, CD68, HLA-DR) and completely down-regulated the originally strong expression of myeloperoxidase and c-myc at the mRNA level. Thus, ATRA- or protein kinase C activator-induced differentiation involved changes associated with maturational processes. Induction of terminal differentiation of leukemic cells by physiological or pharmacological modulators may be able to control the growth of the malignant cells and has therapeutic implications.
Leukemia 1993 Nov
PMID:Modulation of gene expression in the acute promyelocytic leukemia cell line NB4. 790 56

One of the factors regulating the population size of a clone of proliferating cells is the induction of a physiological suicide mechanism known as apoptosis. We studied apoptosis in the HL-60 human promyelocytic leukemia cell line which differentiates when exposed to phorbol ester (S-cell), and in the PET-cell mutant of HL-60 which is defective in its response to phorbol ester. Exposing S-cells to 12-O-tetradecanoylphorbol 13-acetate (TPA) (3 nM and above) induced morphological changes characteristic of apoptosis (visualized by light microscopy), and induced fragmentation of chromatin DNA to oligonucleosomal lengths. These changes were obvious in 48 h. In contrast, 1000 nM TPA for five days did not induce apoptosis in the PET-cell. DNA fragmentation was induced in both cell lines by A23187 (0.25 microM) and etoposide (7 microM). Novobiocin (600 and 900 microM) induced DNA fragmentation in S-cells, but higher concentrations inhibited fragmentation. Novobiocin is believed to induce DNA fragmentation by a direct action on DNA. In the case of PET-cells, novobiocin did not induce DNA fragmentation at any concentration, and prior treatment of PET-cells with novobiocin (300-1200 microM for 30 min) inhibited DNA fragmentation induced by A23187. Novobiocin inhibited cell growth equally in S-cell and PET-cells. It is concluded that the promyelocytes have the capacity to undergo apoptosis in response to agents which activate protein kinase C, and that the PET-cell has a mutation which disables both protein-kinase C-induced and novobiocin-induced DNA fragmentation, leaving intact the ability of novobiocin to protect DNA from calcium-entry-initiated fragmentation. The elucidation of the lesion responsible for the PET phenotype is likely to increase our understanding of this important pathway for regulating cellular proliferation and how it bears on leukemogenesis and chemotherapy.
Leukemia 1993 Nov
PMID:Phorbol ester induces apoptosis in HL-60 promyelocytic leukemia cells but not in HL-60 PET mutant. 823 Dec 52

Activation of protein kinase C results in phosphorylation of a 19-kDa protein termed 19K. Isolation and sequence analysis of a cDNA encoding the 19K protein revealed that this protein has been studied in other systems under different names. The name oncoprotein 18 (Op18) has been proposed on the basis of a postulated up-regulation in neoplastic cells. In the present report we adopt the designation Op18 for the 19K protein, and quantify this phosphoprotein in a series of leukemia/lymphoma cell lines, a panel of non-transformed cells and some terminally differentiated cell types. For this purpose we have developed reagents allowing quantitative Western-blot analysis, and quantification of Op18 on the single cell level by flow cytometric analysis. The data demonstrates a pronounced up-regulation of the Op18 protein in most leukemia/lymphoma cell lines. The HPB-ALL cell line provided the most extreme case and expressed 7 x 10(6) Op18 molecules/cell, which compares with 0.65 x 10(6) Op18 molecules/cell in non-transformed lymphoblastoid cells. The expression of Op18 appears to be restricted to cell types with proliferative potential, but it is clear from our results that up-regulation of Op18 is uncoupled from cellular proliferation. Moreover, by employing an Epstein-Barr virus based shuttle vector, we expressed Op18 cDNA in lymphoblastoid cells. This resulted in a three to fourfold up-regulation of Op18 that did not have any detectable consequences for cell-surface phenotype or cell size. However, increased expression of Op18 resulted in a partial inhibition of cell proliferation. Taken altogether, the results suggest that up-regulation Op18 levels in leukemia/lymphoma cells are strongly associated with, but not a direct cause of tumour progression.
Leukemia 1993 Apr
PMID:Quantitative analysis of the expression and regulation of an activation-regulated phosphoprotein (oncoprotein 18) in normal and neoplastic cells. 846 35

For investigation of relative differences in mRNA expression levels and of correlations in the expression of genes possibly involved in multidrug resistance (MDR) of acute myelogenous leukemias (AML), a complementary DNA polymerase chain reaction (cDNA-PCR) analysis was established for the genes encoding MDR1/P-glycoprotein, the multidrug resistance-associated protein (MRP), topoisomerase II alpha, topoisomerase II beta, topoisomerase I, glutathione S-transferase pi, protein kinase C (PKC) isozymes alpha, beta 1, beta 2, epsilon, eta, theta and cyclin A. In a first descriptive study comprising samples of childhood or adult AML we calculated the mean values from primary (n=14) or relapsed (n=23) states of the diseases, respectively. We found in the latter significant increases of MDR1, MRP, gst pi, and PKC theta gene expression. MDR1 and MRP gene expression levels were generally correlated (rs= +0.4128, P<0.02, n=37), as well as topoisomerase II alpha and cyclin A gene expression levels (rs= +0.8727, P<0.0001, n=35). Within the group of relapsed state AML a significant negative correlation between the gene expression levels of MDR1 and topoisomerase II alpha (rs= -0.5500, P<0.01, n=22) was observed. Remarkably, highly significant positive correlations were found for MDR1/PKC eta (rs= +0.5560, P<0.001, n=32), MRP/PKC theta (rs= +0.6573, P<0.0001, n=34) and MRP/PKC eta (rs= +0.5241, P<0.005, n=32).
Leukemia 1996 Mar
PMID:Expression of PKC isozyme and MDR-associated genes in primary and relapsed state AML. 864 57


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