scholarly journals Neuropeptide-Induced Androgen Independence in Prostate Cancer Cells: Roles of Nonreceptor Tyrosine Kinases Etk/Bmx, Src, and Focal Adhesion Kinase

2001 ◽  
Vol 21 (24) ◽  
pp. 8385-8397 ◽  
Author(s):  
Li-Fen Lee ◽  
Junlin Guan ◽  
Yun Qiu ◽  
Hsing-Jien Kung
Keyword(s):  
Prostate Cancer ◽  
Focal Adhesion Kinase ◽  
G Protein ◽  
Focal Adhesion ◽  
Neurotrophic Factors ◽  
Neurotrophic Factor ◽  
Tyrosine Kinases ◽  
Dominant Negative ◽  
Prostate Cancers ◽  
Nonreceptor Tyrosine Kinases

ABSTRACT The bombesin/gastrin-releasing peptide (GRP) family of neuropeptides has been implicated in various in vitro and in vivo models of human malignancies including prostate cancers. It was previously shown that bombesin and/or neurotensin (NT) acts as a survival and migratory factor(s) for androgen-independent prostate cancers. However, a role in the transition from an androgen-dependent to -refractory state has not been addressed. In this study, we investigate the biological effects and signal pathways of bombesin and NT on LNCaP, a prostate cancer cell line which requires androgen for growth. We show that both neurotrophic factors can induce LNCaP growth in the absence of androgen. Concurrent transactivation of reporter genes driven by the prostate-specific antigen promoter or a promoter carrying an androgen-responsive element (ARE) indicate that growth stimulation is accompanied by androgen receptor (AR) activation. Furthermore, neurotrophic factor-induced gene activation was also present in PC3 cells transfected with the AR but not in the parental line which lacks the AR. Given that bombesin does not directly bind to the AR and is known to engage a G-protein-coupled receptor, we investigated downstream signaling events that could possibly interact with the AR pathway. We found that three nonreceptor tyrosine kinases, focal adhesion kinase (FAK), Src, and Etk/BMX play important parts in this process. Etk/Bmx activation requires FAK and Src and is critical for neurotrophic factor-induced growth, as LNCaP cells transfected with a dominant-negative Etk/BMX fail to respond to bombesin. Etk's activation requires FAK, Src, but not phosphatidylinositol 3-kinase. Likewise, bombesin-induced AR activation is inhibited by the dominant-negative mutant of either Src or FAK. Thus, in addition to defining a new G-protein pathway, this report makes the following points regarding prostate cancer. (i) Neurotrophic factors can activate the AR, thus circumventing the normal growth inhibition caused by androgen ablation. (ii) Tyrosine kinases are involved in neurotrophic factor-mediated AR activation and, as such, may serve as targets of future therapeutics, to be used in conjunction with current antihormone and antineuropeptide therapies.

scholarly journals Essential diurnal Rac1 activation during retinal phagocytosis requires αvβ5 integrin but not tyrosine kinases focal adhesion kinase or Mer tyrosine kinase

2012 ◽  
Vol 23 (6) ◽  
pp. 1104-1114 ◽  
Author(s):  
Yingyu Mao ◽  
Silvia C. Finnemann
Keyword(s):  
Tyrosine Kinase ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Tyrosine Kinases ◽  
Rho Gtpases ◽  
Milk Fat ◽  
Retinal Pigment ◽  
Dominant Negative ◽  
Rpe Cells ◽  
Mer Tyrosine Kinase

Diurnal phagocytosis of shed photoreceptor outer-segment particles by retinal pigment epithelial (RPE) cells belongs to a group of conserved clearance mechanisms employing αv integrins upstream of tyrosine kinases and Rho GTPases. In this study, we tested the interdependence of the tyrosine kinases focal adhesion kinase (FAK) and Mer tyrosine kinase (MerTK) and Rho GTPases during engulfment. RPE cells activated and redistributed Rac1, but not RhoA or Cdc42, during phagocytosis. Toxin B, overexpression of dominant-negative Rac1, or decreasing Rac1 expression prevented particle engulfment. Fluorescence microscopy showed that Rac1 inhibition had no obvious effect on F-actin arrangement in resting RPE but prevented recruitment of F-actin to surface-bound phagocytic particles. Quantification of active GTP-Rac1 in wild-type and mutant RPE in culture and in vivo revealed that Rac1 activation during phagocytosis requires αvβ5 integrin and its ligand milk fat globule EGF factor-8 (MFG-E8) but not the receptor tyrosine kinase MerTK. Abolishing tyrosine kinase signaling downstream of αvβ5 toward MerTK by inhibiting FAK specifically or tyrosine kinases generally neither prevented Rac1 activation nor F-actin recruitment during phagocytosis. Likewise, inhibiting Rac1 had no effect on FAK or MerTK activation. We conclude that MerTK activation via FAK and F-actin recruitment via Rac1 both require MFG-E8–ligated αvβ5 integrin. Both pathways are independently activated and required for clearance phagocytosis.

Focal adhesion kinase is redistributed to focal complexes and mediates cell spreading in macrophages in response to M-CSF

2005 ◽  
Vol 386 (9) ◽  
Author(s):  
Elisabetta Rovida ◽  
Benedetta Lugli ◽  
Valentina Barbetti ◽  
Serena Giuntoli ◽  
Massimo Olivotto ◽  
...  
Keyword(s):  
Focal Adhesion Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Tyrosine Kinases ◽  
Active Form ◽  
Cell Spreading ◽  
Dominant Negative ◽  
Mononuclear Phagocytes ◽  
Relevant Role ◽  
Macrophage Colony

AbstractThe macrophage colony-stimulating factor (M-CSF, CSF-1) regulates survival, proliferation and differentiation of mononuclear phagocytes, as well as macrophage motility and morphology. The latter features are usually regulated by ECM-mediated activation of integrins and subsequent tyrosine phosphorylation of cellular proteins, including focal adhesion kinase (FAK). FAK is phosphorylated by downstream receptor tyrosine kinases as well. We addressed the question whether M-CSF regulates FAK tyrosine phosphorylation in macrophages, and found that M-CSF induces FAK phosphorylation at all known tyrosine residues. This phosphorylation was dependent on Src. Extracellularly-regulated kinase (ERK), Jun N-terminal kinase (JNK) and phosphatidylinositol-3-kinase (PI3K) were found to be negatively involved in M-CSF-induced FAK phosphorylation, as their inhibition resulted in FAK hyper-phosphorylation. Following M-CSF treatment, FAK and the active forms of M-CSFR and Src were redistributed to the cytoskeleton, where active ERK, JNK and PI3K were detectable. Immunofluorescence showed the presence of FAK and its active form in focal complexes following M-CSF treatment. Moreover, cell spreading and adhesion were impaired when FAK tyrosine phosphorylation was abrogated by either transfection with FRNK, a dominant negative form of FAK, or treatment with a number of inhibitors of upstream FAK-activating signals. These results point to a relevant role for FAK in the regulation of cell spreading and adhesion in macrophages.

scholarly journals Focal adhesion kinase and paxillin bind to peptides mimicking beta integrin cytoplasmic domains.

1995 ◽  
Vol 130 (5) ◽  
pp. 1181-1187 ◽  
Author(s):  
M D Schaller ◽  
C A Otey ◽  
J D Hildebrand ◽  
J T Parsons
Keyword(s):  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Cytoplasmic Domain ◽  
Embryo Cell ◽  
Vitro Assay ◽  
Protein Tyrosine ◽  
Signaling Complex

The integrins have recently been implicated in signal transduction. A likely mediator of integrin signaling is focal adhesion kinase (pp125FAK or FAK), a structurally distinct protein tyrosine kinase that becomes enzymatically activated upon engagement of integrins with their ligands. A second candidate signaling molecule is paxillin, a focal adhesion associated, cytoskeletal protein that coordinately becomes phosphorylated on tyrosine upon activation of pp125FAK. Paxillin physically complexes with two protein tyrosine kinases, pp60src and Csk (COOH-terminal src kinase), and the oncoprotein p47gag-crk, each of which could function as part of a paxillin signaling complex. Using an in vitro assay we have established that the cytoplasmic domain of the beta 1 integrin can bind to paxillin and pp125FAK from chicken embryo cell lysates. The NH2-terminal, noncatalytic domain of pp125FAK can bind directly to the cytoplasmic tail of beta 1 and recognizes integrin sequences distinct from those involved in binding to alpha-actinin. Paxillin binding is independent of pp125FAK binding despite the fact that both bind to the same region of beta 1. These results demonstrate that the cytoplasmic domain of the beta subunits of integrins contain binding sites for both signaling molecules and structural proteins suggesting that integrins can coordinate the generation of cytoplasmic signals in addition to their role in anchoring components of the cytoskeleton.

scholarly journals Inhibition of focal adhesion kinase increases adult olfactory stem cell self-renewal and neuroregeneration through ciliary neurotrophic factor

2020 ◽  
Vol 49 ◽  
pp. 102061
Author(s):  
Cuihong Jia ◽  
Joe Oliver ◽  
Dustin Gilmer ◽  
Chiharu Lovins ◽  
Diego J. Rodriguez-Gil ◽  
...  
Keyword(s):  
Stem Cell ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Neurotrophic Factor ◽  
Ciliary Neurotrophic Factor ◽  
Self Renewal

Osmotic shrinkage elicits FAK- and Src phosphorylation and Src-dependent NKCC1 activation in NIH3T3 cells

2015 ◽  
Vol 308 (2) ◽  
pp. C101-C110 ◽  
Author(s):  
Line Jee Hartmann Rasmussen ◽  
Helene Steenkær Holm Müller ◽  
Bente Jørgensen ◽  
Stine Falsig Pedersen ◽  
Else Kay Hoffmann
Keyword(s):  
Focal Adhesion ◽  
Tyrosine Kinases ◽  
Volume Regulation ◽  
Mammalian Cells ◽  
Myosin Light Chain ◽  
Janus Kinase ◽  
Nih3t3 Cells ◽  
Src Inhibitor ◽  
Nonreceptor Tyrosine Kinases

The mechanisms linking cell volume sensing to volume regulation in mammalian cells remain incompletely understood. Here, we test the hypothesis that activation of nonreceptor tyrosine kinases Src, focal adhesion kinase (FAK), and Janus kinase-2 (Jak2) occurs after osmotic shrinkage of NIH3T3 fibroblasts and contributes to volume regulation by activation of NKCC1. FAK phosphorylation at Tyr397, Tyr576/577, and Tyr861 was increased rapidly after exposure to hypertonic (575 mOsm) saline, peaking after 10 (Tyr397, Tyr576/577) and 10–30 min (Tyr861). Shrinkage-induced Src family kinase autophosphorylation (pTyr416-Src) was induced after 2–10 min, and immunoprecipitation indicated that this reflected phosphorylation of Src itself, rather than Fyn and Yes. Phosphorylated Src and FAK partly colocalized with vinculin, a focal adhesion marker, after hypertonic shrinkage. The Src inhibitor pyrazolopyrimidine-2 (PP2, 10 μM) essentially abolished shrinkage-induced FAK phosphorylation at Tyr576/577 and Tyr861, yet not at Tyr397, and inhibited shrinkage-induced NKCC1 activity by ∼50%. The FAK inhibitor PF-573,228 augmented shrinkage-induced Src phosphorylation, and inhibited shrinkage-induced NKCC1 activity by ∼15%. The apparent role of Src in NKCC1 activation did not reflect phosphorylation of myosin light chain kinase (MLC), which was unaffected by shrinkage and by PP2, but may involve Jak2, a known target of Src, which was rapidly activated by osmotic shrinkage and inhibited by PP2. Collectively, our findings suggest a major role for Src and possibly the Jak2 axis in shrinkage-activation of NKCC1 in NIH3T3 cells, whereas no evidence was found for major roles for FAK and MLC in this process.

Genistein-stimulated adherence of prostate cancer cells is associated with the binding of focal adhesion kinase to beta-l-integrin

1996 ◽  
Vol 14 (4) ◽  
pp. 389-398 ◽  
Author(s):  
Raymond Bergan ◽  
Edward Kyle ◽  
Phuongmai Nguyen ◽  
Jane Trepel ◽  
Christian Ingui ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Focal Adhesion Kinase ◽  
Cancer Cells ◽  
Focal Adhesion ◽  
Prostate Cancer Cells
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