Raf-1 kinase activation is uncoupled from downstream MEK/ERK pathway in cells treated with Src tyrosine kinase inhibitor PP2

2006 ◽  
Vol 350 (2) ◽  
pp. 450-456 ◽  
Author(s):  
Michael Lee
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Kinase Inhibitor ◽  
Erk Pathway ◽  
Src Tyrosine Kinase ◽  
Kinase Activation ◽  
In Cells

Secretin regulates paracellular permeability in canine gastric monolayers by a Src kinase-dependent pathway

2002 ◽  
Vol 283 (4) ◽  
pp. G893-G899 ◽  
Author(s):  
Monica C. Chen ◽  
Travis E. Solomon ◽  
Eduardo Perez Salazar ◽  
Robert Kui ◽  
Enrique Rozengurt ◽  
...  
Keyword(s):  
Gastric Mucosa ◽  
Epithelial Cells ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Tyrosine Phosphorylation ◽  
Molecular Mechanisms ◽  
Kinase Inhibitor ◽  
Paracellular Permeability ◽  
Maximal Response ◽  
Src Tyrosine Kinase

Previous studies found that epidermal growth factor (EGF) decreased paracellular permeability in gastric mucosa, but the other physiological regulators and the molecular mechanisms mediating these responses remain undefined. We investigated the role of secretin and Src in regulating paracellular permeability because secretin regulates gastric chief cell function and Src mediates events involving the cytoskeletal-membrane interface, respectively. Confluent monolayers were formed from canine gastric epithelial cells in short-term culture on Transwell filter inserts. Resistance was monitored in the presence of secretin with or without specific kinase inhibitors. Tyrosine phosphorylation of Src at Tyr416 was measured with a site-specific phosphotyrosine antibody. Basolateral, but not apical, secretin at concentrations from 1 to 100 nM dose dependently increased resistance; this response was rapid and sustained over hours. PP2 (10 μM), a selective Src tyrosine kinase inhibitor, but not the inactive isomer PP3, abolished the increase in resistance by secretin but only modestly attenuated apical EGF effects. AG-1478 (100 nM), a specific EGF receptor tyrosine kinase inhibitor, attenuated the resistance increase to EGF but not secretin. Secretin, but not EGF, induced tyrosine phosphorylation of Src at Tyr416 in a dose-dependent fashion, with the maximal response observed at 1 min. PP2, but not PP3, dramatically inhibited this tyrosine phosphorylation. Secretin increases paracellular resistance in gastric mucosa through a Src-mediated pathway, while the effect of EGF is Src independent. Src appears to mediate the physiological effects of this Gs-coupled receptor in primary epithelial cells.

The Tyrosine Kinase Inhibitor Adaphostin (NSC 680410), but Not Imatinib Mesylate, Inhibits Survival and Src Tyrosine Kinase Family- Triggered Signaling Pathways of MM Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3352-3352
Author(s):  
Klaus Podar ◽  
Melissa Simoncini ◽  
Yu-Tzu Tai ◽  
Martin Sattler ◽  
Kenji Ishitsuka ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Signaling Pathways ◽  
Imatinib Mesylate ◽  
Kinase Inhibitor ◽  
K562 Cells ◽  
Parp Cleavage ◽  
Src Tyrosine Kinase ◽  
Kinase Family ◽  
Long Term Treatment

Abstract The tyrosine kinase inhibitor adaphostin is a member of the tyrophostin family of small molecules that interfere with peptide binding rather, than targeting the kinase ATP-binding site. Adaphostin has therefore been examined as an alternative to the 2-phenylaminopyrimidine derivate imatinib mesylate, with remarkable efficacy in the treatment of chronic myeloic leukemia (CML). Previous studies show that adaphostin induces apoptosis: (1) in Bcr/Abl+ cells more rapidly than imatinib mesylate; (2) in imatinib mesylate resistant cells; and (3) in Bcr/ Abl - cells. Imatinib mesylate has minimal, if any activity in MM; the efficacy of adaphostin in multiple myeloma (MM) is unknown. Here we compare the effects of adaphostin and imatinib mesylate against human MM cells. Our results show concentration-dependent apoptosis in MM.1S, U266, OPM-2, INA-6, RPMI8226 and RPMI-Dox40 MM cells after treatment with adaphostin, but not with imatinib mesylate. Imatinib mesylate induced more than 50% apoptosis in K562 cells using concentrations as low as 1mM, which served as a positive control. Moreover, adaphostin, but not imatinib mesylate, induced caspase-9, caspase-8, and PARP cleavage, as well as downregulation of Mcl-1, in MM cells. Further results demonstrated that adaphostin induces peroxide production and DNA strand breaks after long-term treatment. Importantly MM cell proliferation induced by MM cell binding to BMSCs was abrogated by adaphostin- treatment. IL-6 and IGF-1 signaling and sequelae triggered by these cytokines are important growth, survival, and drug resistance factors in MM; conversely, adaphostin but not imatinib mesylate, inhibited phosphorylation of Src tyrosine kinase family, Akt-1, and ERK. Taken together, our studies in MM cells show that (1) adaphostin- inhibits IGF-1- and IL-6- triggered signaling pathways as well as (2) induces reactive oxygen species and apoptosis. These studies therefore provide the preclinical framework for its clinical evaluation to improve patient outcome in MM.

EFFECT OF SRC TYROSINE KINASE INHIBITOR, PP1, ON THE CYTOKINE RESPONSE INDUCED BY LIPOPOLYSACCHARIDE.

2005 ◽  
Vol 33 ◽  
pp. A139
Author(s):  
Sandra D Buttram ◽  
Patrick M Kochanek ◽  
Delbert G Gillespie ◽  
Zaichuan Mi ◽  
Edwin K Jackson
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Kinase Inhibitor ◽  
Cytokine Response ◽  
Src Tyrosine Kinase

scholarly journals A role for src tyrosine kinase in regulating adrenal aldosterone production

2001 ◽  
Vol 26 (3) ◽  
pp. 207-215 ◽  
Author(s):  
R Sirianni ◽  
R Sirianni ◽  
BR Carr ◽  
V Pezzi ◽  
WE Rainey
Keyword(s):  
Protein Synthesis ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Tyrosine Kinases ◽  
Kinase Inhibitor ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Src Tyrosine Kinase ◽  
Src Tyrosine Kinases ◽  
Aldosterone Production

Adrenal aldosterone synthesis is influenced by a variety of factors. The major physiological regulators of aldosterone production are angiotensin II (Ang IotaIota) and potassium (K(+)). Ang IotaIota stimulates aldosterone production through the activation of multiple intracellular signaling pathways. It has recently been demonstrated that Ang IotaIota activates src tyrosine kinases in vascular smooth muscle cells. The src family of tyrosine kinases are widely distributed non-receptor kinases that influence several signal transduction pathways. In the present study we evaluated the effect of a selective src family inhibitor, PP2, on aldosterone production using a human adrenocortical carcinoma-derived (H295R) cell line. Treatments for 6 or 48 h with PP2 (0.3 microM-10 microM) inhibited basal, Ang IotaIota, K(+) and dibutyryladenosine cyclic monophosphate (dbcAMP) stimulation of aldosterone production in a concentration-dependent manner. PP2 did not affect cell viability at any of the concentrations tested. Moreover, time course studies using PP2 (10 microM) for 6, 12, 24, and 48 h revealed a time-dependent inhibition of aldosterone production. Inhibition by PP2 (0.3-10 microM) was also observed for the metabolism of 22R-hydroxycholesterol (22R-OHChol) to aldosterone in H295R cells. Since 22R-OHChol is a substrate for cytochrome P450 side-chain cleavage enzyme (CYP11A) that does not require steroidogenic acute regulatory (StAR) protein for transport to the inner mitochondrial membrane, these results suggest that PP2 inhibition occurred beyond the rate-limiting step in aldosterone synthesis. Genistein, a non-specific tyrosine kinase inhibitor also blocked aldosterone production, but the inhibition was the result of a non-specific effect on 3beta-hydroxysteroid dehydrogenase (3betaHSD). In contrast, PP2 did not appear to act as a direct inhibitor of 3betaHSD activity. To further investigate the site of PP2 action, we examined its effect on H295R cell metabolism of [(14)C]progesterone using thin layer chromatography. PP2 treatment for 48 h caused an increase in the conversion of progesterone to 17alpha-hydroxyprogesterone. To determine if this apparent increase in 17alpha-hydroxylase activity was due to increased transcript, we examined the effect of PP2 on CYP17 mRNA. PP2 treatment caused an increase in CYP17 mRNA without an effect on 3betaHSD mRNA levels. Inhibition of protein synthesis with cycloheximide increased basal levels of CYP17 mRNA levels and blocked the induction observed by PP2. This suggests that new protein synthesis is a necessary part of PP2 induction of CYP17. Taken together these data suggest that the src tyrosine kinase inhibitor, PP2, is a potent inhibitor of aldosterone production. One mechanism for the inhibition is through an induction of CYP17 mRNA and enzyme activity. Src tyrosine kinases, therefore, may be involved with the promotion of a glomerulosa phenotype through the inhibition of CYP17 expression.

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