Protein kinase C-independent stimulation of activator protein-1 and c-Jun N-terminal kinase activity in human endometrial cancer cells by the LHRH agonist triptorelin

OBJECTIVE: The expression of luteinizing hormone-releasing hormone (LHRH) and its receptor as a part of an autocrine regulatory system of cell proliferation has been demonstrated in a number of human malignant tumours, including cancers of the endometrium. The signalling pathway through which LHRH acts in endometrial cancer is distinct from that in pituitary gonadotrophs. The LHRH receptor interacts with the mitogenic signal transduction of growth factor receptors via activation of a phosphotyrosine phosphatase, resulting in down-regulation of cancer cell proliferation. In addition, LHRH activates nucleus factor kappaB (NFkappaB) and protects the cancer cells from apoptosis. This study was conducted to investigate additional signalling mechanisms of the LHRH receptor cooperating with NFkappaB in endometrial cancer cells. DESIGN: The LHRH agonist triptorelin-induced activator protein-1 (AP-1) activation was analysed using a pAP-1-SEAP reporter gene assay. Expression of c-jun mRNA was quantified using quantitative reverse transcription (RT)-PCR. c-Jun N-terminal kinase (JNK) activity was measured by quantification of phosphorylated c-Jun protein. RESULTS: Treatment of Ishikawa and Hec-1A human endometrial cancer cells with 100 nM triptorelin resulted in a 3.1-fold and 3.5-fold activation of AP-1 respectively (P<0.05). If the cells had been made quiescent, treatment with triptorelin (100 nM) resulted in a 41.7-fold and 48.6-fold increase of AP-1 activation respectively (P<0.001). This effect was completely blocked by simultaneous treatment with pertussis toxin (PTX). A 17.6-fold and 17.3-fold increase of c-jun mRNA expression respectively (P<0.001) was obtained after 20 min of stimulation with triptorelin (100 nM). Treatment with 1 nM triptorelin resulted in a 12.5-fold or an 11.9-fold increase, and treatment with 10 pM triptorelin resulted in a 6.5-fold or a 5.2-fold increase of maximal c-jun mRNA expression respectively (P<0.001). Maximal c-Jun phosphorylation (68.5-fold and 60.2-fold, respectively, P<0.001) was obtained after 90 min incubation with triptorelin (100 nM). CONCLUSIONS: These results suggest that the LHRH agonist triptorelin stimulates the activity of AP-1 in human endometrial cancer cells mediated through PTX-sensitive G-protein alphai. In addition, triptorelin activates JNK, known to activate AP-1. In earlier investigations we have shown that triptorelin does not activate phospholipase and protein kinase C (PKC) in endometrial cancer cells. In addition, it has been demonstrated that triptorelin inhibits growth factor-induced mitogen activated protein kinase (MAPK, ERK) activity. Thus triptorelin-induced activation of the JNK/AP-1 pathway in endometrial cancer cells is independent of the known AP-1 activators, PKC or MAPK (ERK).

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Cisplatin increases B-cell-lymphoma-2 expression via activation of protein kinase C and Akt2 in endometrial cancer cells

International Journal of Cancer ◽

10.1002/ijc.26183 ◽

2011 ◽

Vol 130 (8) ◽

pp. 1755-1767 ◽

Cited By ~ 17

Author(s):

Alexandre Rouette ◽

Sophie Parent ◽

Julie Girouard ◽

Valérie Leblanc ◽

Eric Asselin

Keyword(s):

Endometrial Cancer ◽

Protein Kinase C ◽

Protein Kinase ◽

B Cell ◽

Cancer Cells ◽

Cell Lymphoma ◽

B Cell Lymphoma ◽

Kinase C

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1-O-Octadecyl-2-O-methylglycerophosphocholine inhibits protein kinase C- dependent phosphorylation of endogenous proteins in MCF-7 cells

Biochemical Journal ◽

10.1042/bj3240897 ◽

1997 ◽

Vol 324 (3) ◽

pp. 897-902 ◽

Cited By ~ 10

Author(s):

Xi ZHOU ◽

Gilbert ARTHUR

Keyword(s):

Cell Proliferation ◽

Protein Kinase C ◽

Protein Kinase ◽

Cancer Cells ◽

Epithelial Cancer ◽

Intact Cells ◽

Kinase C ◽

Mechanism Of Inhibition ◽

Endogenous Proteins ◽

Mcf 7

Studies with leukaemic cells, based primarily on in vitro assays, have suggested that antitumour ether lipids have only a moderate effect on protein kinase C (PKC) activity, and, furthermore, inhibition of PKC is unlikely to be involved in the mechanism of inhibition of cell proliferation by these compounds. To determine if this is also the case for epithelial cancer cells, we examined the effect of 1-O-octadecyl-2-O-methylglycerophosphocholine (ET18-OCH3) on PKC-induced phosphorylation of endogenous proteins in MCF-7 cells under incubation conditions where the drug inhibited cell proliferation. As expected, stimulation of quiescent 32P-labelled MCF-7 cells with 1 μM PMA resulted in the phosphorylation of a number of proteins. The PMA-induced phosphorylation of the proteins was abolished by preincubation of the cells with Ro 31-8220 (5 μM) for 20 min, or 10 μg/ml ET18-OCH3 for 3 h before stimulation with PMA. Thus under incubation conditions where ET18-OCH3 inhibited the proliferation of MCF-7 cells, the ether lipid potently inhibited the activity of PKC in intact cells. This inhibition was unlikely to be due to the effect of the compound on PKC translocation since there was little effect of ET18-OCH3 on the translocation of the α, γ and ϵ species of PKC. These results suggest that a role for the inhibition of PKC activity by ET18-OCH3 in the mechanism of inhibition of cell proliferation by ET18-OCH3 cannot yet be discounted in epithelial cancer cells. In addition, we also observed that ET18-OCH3 enhanced the phosphorylation of selected proteins under basal unstimulated conditions. Although some of these proteins were also observed to be phosphorylated in response to PMA stimulation, the phosphorylation induced by ET18-OCH3 was not inhibited by Ro 31-8220, indicating that this was not mediated by PKC.

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Diacylglycerol generated during sphingomyelin synthesis is involved in protein kinase C activation and cell proliferation in Madin-Darby canine kidney cells

Biochemical Journal ◽

10.1042/bj20021732 ◽

2003 ◽

Vol 373 (3) ◽

pp. 917-924 ◽

Cited By ~ 20

Author(s):

Jorge CERBÓN ◽

Rosa del Carmen LÓPEZ-SÁNCHEZ

Keyword(s):

Cell Proliferation ◽

Protein Kinase C ◽

Protein Kinase ◽

Fold Increase ◽

Kidney Cells ◽

Madin Darby Canine Kidney ◽

Kinase C ◽

Pkc Activation ◽

Darby Canine Kidney ◽

Canine Kidney

We have investigated the effects of inhibiting sphingomyelin (SM) biosynthesis on cellular diacylglycerol (DAG) content and protein kinase C (PKC) activation during growth initiation in Madin–Darby canine kidney cells. We utilized β-chloroalanine (BCA) to inactivate serine C-palmitoyltransferase, the first enzyme in the sphingolipid biosynthesis pathway. This inactivation prevented growth, but did not affect viability. When the inhibitor was replaced with fresh culture medium, the cells continued their proliferation in a normal way. BCA (2 mM) inhibited [32P]Pi, [3H]palmitic acid and [methyl-3H]choline incorporation into SM, but did not influence the synthesis of other major phospholipids. SM synthesis and DAG generation were decreased by 51% and 47.6% respectively. Particulate PKC activity was not observed in cells incubated with BCA, in contrast with a 5-fold increase in control cells. BCA inhibited 75% of the [3H]thymidine incorporation, and the cells were arrested before the S phase of the cell cycle. Moreover, exogenous d-erythrosphingosine restored SM synthesis, DAG generation and cell proliferation. These data indicate that the contribution of DAG generated during SM synthesis plays an important role in PKC activation and cell proliferation.

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Protein kinase C alpha (PKCα) regulates growth and invasion of endometrial cancer cells

Journal of Cellular Physiology ◽

10.1002/jcp.21741 ◽

2009 ◽

Vol 220 (1) ◽

pp. 112-118 ◽

Cited By ~ 18

Author(s):

James M. Haughian ◽

Andrew P. Bradford

Keyword(s):

Endometrial Cancer ◽

Protein Kinase C ◽

Protein Kinase ◽

Cancer Cells ◽

Kinase C ◽

Protein Kinase C Alpha

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Crosstalk of protein kinase C ε with Smad2/3 promotes tumor cell proliferation in prostate cancer cells by enhancing aerobic glycolysis

Cellular and Molecular Life Sciences ◽

10.1007/s00018-018-2914-9 ◽

2018 ◽

Vol 75 (24) ◽

pp. 4583-4598 ◽

Cited By ~ 5

Author(s):

Wanfu Xu ◽

Fangyin Zeng ◽

Songyu Li ◽

Guihuan Li ◽

Xiaoju Lai ◽

...

Keyword(s):

Prostate Cancer ◽

Cell Proliferation ◽

Protein Kinase C ◽

Protein Kinase ◽

Tumor Cell ◽

Cancer Cells ◽

Aerobic Glycolysis ◽

Tumor Cell Proliferation ◽

Prostate Cancer Cells ◽

Kinase C

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Induction of the 47 kDa platelet substrate of protein kinase C during differentiation of HL-60 cells

Biochemical Journal ◽

10.1042/bj2430249 ◽

1987 ◽

Vol 243 (1) ◽

pp. 249-253 ◽

Cited By ~ 13

Author(s):

M Tyers ◽

R A Rachubinski ◽

C S Sartori ◽

C B Harley ◽

R J Haslam

Keyword(s):

Cell Proliferation ◽

Protein Kinase C ◽

Retinoic Acid ◽

Protein Kinase ◽

Fold Increase ◽

Immunoblot Analysis ◽

Myeloid Differentiation ◽

Early Event ◽

Kinase C ◽

Low Levels

Immunoblot analysis showed that the 47 kDa platelet substrate of protein kinase C (P47) was expressed at low levels in undifferentiated HL-60 leukaemia cells. Treatment of these cells with dimethyl sulphoxide, 1 alpha,25-dihydroxycholecalciferol or retinoic acid caused progressive increases in P47 content. Retinoic acid (1 microM) elicited the largest response, a 4-fold increase in P47 protein after 7 days that was accompanied by an increase in translatable P47 mRNA. The induction of P47 by retinoic acid preceded cessation of cell proliferation and development of the capacity to reduce Nitro Blue Tetrazolium, indicating that its expression is an early event in the myeloid differentiation of HL-60 cells.

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