127,398 research outputs found
FAK deletion promotes p53-mediated induction of p21, DNA-damage responses and radio-resistance in advanced squamous cancer cells
No full textFocal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase that is elevated in a variety of human cancers. While FAK is implicated in many cellular processes that are perturbed in cancer, including proliferation, actin and adhesion dynamics, polarisation and invasion, there is only some limited information regarding the role of FAK in radiation survival. We have evaluated whether FAK is a general radio-sensitising target, as has been suggested by previous reports. We used a clean genetic system in which FAK was deleted from mouse squamous cell carcinoma (SCC) cells (FAK -/-), and reconstituted with exogenous FAK wild type (wt). Surprisingly, the absence of FAK was associated with increased radio-resistance in advanced SCC cells. FAK re-expression inhibited p53-mediated transcriptional up-regulation of p21, and a sub-set of other p53 target genes involved in DNA repair, after treatment with ionizing radiation. Moreover, p21 depletion promoted radio-sensitisation, implying that FAK-mediated inhibition of p21 induction is responsible for the relative radio-sensitivity of FAK-proficient SCC cells. Our work adds to a growing body of evidence that there is a close functional relationship between integrin/FAK signalling and the p53/p21 pathway, but demonstrates that FAK's role in survival after stress is context-dependent, at least in cancer cells. We suggest that there should be caution when considering inhibiting FAK in combination with radiation, as this may not always be clinically advantageous
Modelling stromal FAK regulation of tumour growth, angiogenesis and progression
No full textPhDThe growth of tumours within a whole organism depends on the tumour
microenvironment. This involves both resident stromal cells, such as endothelial cells
and fibroblasts, and also bone marrow derived stromal cells. Integrins and growth
factor receptors are known regulators of the tumour stroma. Since focal adhesion
kinase (FAK) is a downstream effector of both integrins and growth factor receptors it
likely also plays an important role in the regulation of the tumour microenvironment.
Using adult mice where FAK is deleted ubiquitously after treatment with tamoxifen
my data demonstrate that loss of stromal FAK inhibits tumour growth and
angiogenesis but increases metastasis burden in experimental metastasis assays even
when the tumour cells themselves still express FAK. Moreover, my data indicate loss
of FAK in the bone marrow (BM) compartment and specifically in myeloid cells is
sufficient to enhance tumour metastasis in experimental metastasis assays and in a
spontaneous tumour model. In contrast loss of bone marrow FAK was not sufficient
to affect primary tumour growth or angiogenesis. Taken together these data
demonstrate that bone marrow derived FAK plays a significant but differential role in
primary tumour growth and metastasis.
4
In a parallel study, I have developed a novel set of transgenic mice to enable us to
dissect the mechanism of FAK function in primary tumour growth, metastasis and
angiogenesis. I have generated point-mutant FAK knockin-knockout mice where
mutant FAK is inducibly expressed (knockin) and endogenous FAK deleted
(knockout) in specific cell types in adult mice. Here I show efficient deletion of
mouse FAK and expression of FAK 861F mutant in tamoxifen-treated endothelial
cells isolated from mice. Importantly the FAK 861F mutation in endothelial cells was
sufficient to decrease tumour growth and angiogenesis in vivo suggesting that the
FAK-P-Y861 phosphorylation site plays an important role in tumour growth and
angiogenesis
Epidermal Growth Factor Receptor substrate 8 (Eps8) controls Src/FAK-dependent phenotypes in squamous carcinoma cells
No full textEps8 is an actin regulatory scaffold protein increased in Squamous Cell Carcinoma (SCC) cells. It forms a complex with both Focal Adhesion Kinase (FAK) and c-Src in SCC cells derived from the DMBA/TPA model of skin carcinogenesis. Here, we describe two new roles for Eps8. Firstly, it controls the spatial distribution of active c-Src in a FAK-dependent manner. Specifically, Eps8 participates in, and regulates, a biochemical complex with c-Src and drives c-Src's trafficking to autophagic structures that SCC cells use to cope with high levels of active c-Src when FAK is absent. Secondly, when FAK is expressed in SCC cells, so tethering active c-Src at focal adhesion complexes, Eps8 is also recruited to focal adhesions and is required for FAK-dependent polarization and invasion. Therefore, Eps8 is a critical mediator of Src/FAK-regulated processes; it participates in specific biochemical complexes and promotes actin re-arrangements that determine c-Src's spatial localization and Src/FAK functions in invasive migration.</p
New insights on Fak and Fak inhibitors
No full textBackground: Focal adhesion kinase (Fak) is a cytoplasmic protein tyrosine kinase
overexpressed and activated in different solid cancers; it has shown an important
role in metastasis formation, cell migration, invasion and angiogenesis and consequently
it has been proposed as a potential target in cancer therapy, particularly in a metastatic
phase. In recent years, different investigations have highlighted the importance of new
Fak inhibitors as potential anti-cancer drugs, but other studies evidenced its role in different
pathologies related to the cardiac function or viral infection.
Methods: An extensive bibliographic research (104 references) has been done concerning
the structure of Fak, its importance in tumor development, but also in other pathologies
currently under study. The compounds currently subjected to clinical studies were
therefore treated using the appropriate databases. Finally, the main chemical scaffolds
currently under preclinical investigation were analyzed, focusing on their molecular structures
and on the activity structure relationships (SAR).
Results: At the moment, only a few reversible ATP-competitive inhibitors are under investigation
in pre-clinical studies and clinical trials. Other compounds, with different
chemical scaffolds, are investigated to obtain more active and selective Fak inhibitors.
This mini-review is a summary of different Fak functions in cancer and other pathologies;
the compounds today in clinical trials and the recent chemical scaffolds (also included
in patents) giving the most interesting results are investigated. In addition, PROTAC
molecules are reported.
Conclusion: All reported results evidenced that additional studies are necessary to design
and synthesize new selective and more active compounds, although promising information
has been obtained from associations between Fak inhibitors and other different anti-
cancer drugs. In addition, the other important roles evidenced, both at the nuclear level
and in non-cancerous cells, make this protein an increasingly important target in pharmaceutical
chemistry
FAK-mediated mechanotransduction in skeletal regeneration
No full textThe majority of cells are equipped to detect and decipher physical stimuli, and then react to these stimuli in a cell type-specific manner. Ultimately, these cellular behaviors are synchronized to produce a tissue response, but how this is achieved remains enigmatic. Here, we investigated the genetic basis for mechanotransduction using the bone marrow as a model system. We found that physical stimuli produced a pattern of principal strain that precisely corresponded to the site-specific expression of sox9 and runx2, two transcription factors required for the commitment of stem cells to a skeletogenic lineage, and the arrangement and orientation of newly deposited type I collagen fibrils. To gain insights into the genetic basis for skeletal mechanotransduction we conditionally inactivated focal adhesion kinase (FAK), an intracellular component of the integrin signaling pathway. By doing so we abolished the mechanically induced osteogenic response and thus identified a critical genetic component of the molecular machinery required for mechanotransduction. Our data provide a new framework in which to consider how physical forces and molecular signals are synchronized during the program of skeletal regeneration
Phosphorylation status of FAK and FAK substrates in FAK<sup>-/-</sup> cells re-expressing wild-type FAK and FAK<sup>I936/I998</sup>.
No full text<p>(A) Graphs show decreased FAK phosphorylation at Tyr<sup>397</sup>, Tyr<sup>576</sup> and Tyr<sup>925</sup> in FAK<sup>I936/I998</sup> cells compared to wild-type FAK cells (*p<0.013, **p<0.0002; n = 4 to 6 independent experiments). (B) Representative Western blots showing the phosphorylation states of paxillin and p130Cas in FAK<sup>-/-</sup>, FAK and FAK<sup>I936/I998</sup>-expressing cells. Graphs show decreased phosphorylation of paxillin in both FAK<sup>I936/I998</sup> cells and FAK<sup>-/-</sup> cells (*p<0.03) compared to wild-type FAK cells (P = 0.0097, F = 6.165) and decrease phosphorylation of p130CAS in FAK<sup>I936/I998</sup> cells (***p<0.001) and FAK<sup>-/-</sup> cells (*p<0.05) compared to wild-type FAK cells (p = 0.0004, F = 12.68; n = 3 to 8 independent experiments).</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Costamere remodeling with muscle loading and unloading in healthy young men
No full textCostameres are mechano-sensory sites of focal adhesion in the sarcolemma that provide a structural anchor for
myofibrils. Their turnover is regulated by integrin-associated focal adhesion kinase (FAK). We hypothesized that\ud
changes in content of costamere components (beta 1 integrin, FAK, meta-vinculin, gamma-vinculin) with
increased and reduced loading of human anti-gravity muscle would: (i) relate to changes in muscle size and
molecular parameters of muscle size regulation [p70S6K, myosin heavy chain (MHC)1 and MHCIIA];
(ii) correspond to adjustments in activity and expression of FAK, and its negative regulator, FRNK; and
(iii) reflect the temporal response to reduced and increased loading. Unloading induced a progressive decline in
thickness of human vastus lateralis muscle after 8 and 34 days of bedrest (-4% and -14%, respectively; n = 9),
contrasting the increase in muscle thickness after 10 and 27 days of resistance training (+5% and +13%; n = 6).
Changes in muscle thickness were correlated with changes in cross-sectional area of type I muscle fibers
(r = 0.66) and beta 1 integrin content (r = 0.76) at the mid-point of altered loading. Changes in meta-vinculin
and FAK-pY397 content were correlated (r = 0.85) and differed, together with the changes of beta 1 integrin,
MHCI, MHCII and p70S6K, between the mid- and end-point of resistance training. By contrast, costamere
protein level changes did not differ between time points of bedrest. The findings emphasize the role of FAKregulated
costamere turnover in the load-dependent addition and removal of myofibrils, and argue for two
phases of muscle remodeling with resistance training, which do not manifest at the macroscopic level
Quantification of focal adhesions in FAK, FAK<sup>I936/I998</sup> and FAK<sup>-/-</sup> cells.
No full text<p>(A) Confocal images from fixed FAK<sup>-/-</sup> cells expressing or not wild-type or mutant FAK-GFP and immunostained for paxillin. Evaluation of paxillin-containing FAs reveals no significant decrease in the number of FAs in FAK<sup>I936/I998</sup> cells as compared to FAK<sup>-/-</sup> and FAK cells (P = 0.0602, F = 2.958; n = 3 independent experiments with 15 to 28 cells and more than 600 FAs counted per condition). Scale bar, 20 μm. (B) Size-distribution of FAs shows a clear deficit of sub-micron sized FAs in FAK<sup>I936/I998</sup> (02 ***p<0.001; 0.52 **p<0.01) and FAK<sup>-/-</sup> cells (02 ***p<0.001) compared to FAK cells.</p
p130Cas distribution in FAK<sup>-/-</sup>, wild-type FAK and FAK<sup>I936/I998</sup> cells.
No full text<p>(A) Confocal images of fixed FAK<sup>-/-</sup>cells expressing or not (NT, non-transfected cells) wild-type or mutant FAK-GFP (left panel) and immunostained for p130Cas (right panel). Note the localization of p130Cas at FAs in both FAK<sup>-/-</sup>, FAK<sup>I936/I998</sup> and FAK cells. Scale bar, 20 μm. (B) Confocal images of fixed FAK<sup>-/-</sup>cells expressing or not (NT, non-transfected cells) wild-type or mutant FAK-GFP (left panel) and immunostained for P-p130Cas (right panel). Note the high level of P-p130Cas at FAs in GFP-FAK cells (upper panel) and the lack of P-p130Cas staining at FAs in FAK<sup>I936/I998</sup>-GFP cells (lower panel). Scale bar, 20 μm. Quantification of the mean fluorescence intensity at FAs shows a significant reduction of P-p130Cas staining for both FAK<sup>I936/I998</sup> compared to FAK and FAK<sup>-/-</sup> cells and for FAK<sup>-/-</sup> cells compared to FAK cells (P = 0.0005, F = 9.434; ***p<0.0005, *p<0.05 and <sup>†</sup>p<0.05 respectively, n = 3 independent experiments with 12 to 15 cells analyzed and more than 300 FAs analyzed for each condition).</p
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