Enhanced v-Src-induced oncogenic transformation in the absence of focal adhesion kinase is mediated by phosphatidylinositol 3-kinase

Moissoglu, Konstadinos; Sachdev, Sanjay; Gelman, Irwin H.

doi:10.1016/j.bbrc.2005.03.025

Cited by 12 publications

(20 citation statements)

References 55 publications

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“…Although the full phosphorylation of some cellular substrates, such as Endophilin A2, requires both FAK and Src [29], it is possible that such substrates are dispensable for oncogenic transformation. A further complication is that phosphorylation of some substrates, such as PI3K, varied only under conditions of anchorage independence [30]. Indeed, we demonstrated that the superactivation of PI3K was required and sufficient for the enhanced v-Src-induced anchorage-independent growth of FAK-/- fibroblasts [30].…”

Section: Introductionmentioning

confidence: 99%

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Paxillin-Y118 phosphorylation contributes to the control of Src-induced anchorage-independent growth by FAK and adhesion

Sachdev

Gelman

2009

BMC Cancer

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BackgroundFocal adhesion kinase (FAK) and Src are protein tyrosine kinases that physically and functionally interact to facilitate cancer progression by regulating oncogenic processes such as cell motility, survival, proliferation, invasiveness, and angiogenesis.MethodTo understand how FAK affects oncogenesis through the phosphorylation of cellular substrates of Src, we analyzed the phosphorylation profile of a panel of Src substrates in parental and v-Src-expressing FAK+/+ and FAK-/- mouse embryo fibroblasts, under conditions of anchorage-dependent (adherent) and -independent (suspension) growth.ResultsTotal Src-induced cellular tyrosine phosphorylation as well as the number of phosphotyrosyl substrates was higher in suspension versus adherent cultures. Although the total level of Src-induced cellular phosphorylation was similar in FAK+/+ and FAK-/- backgrounds, the phosphorylation of some substrates was influenced by FAK depending on adherence state. Specifically, in the absence of FAK, Src induced higher phosphorylation of p190RhoGAP, paxillin (poY118) and Crk irrespective of adhesion state, PKC-δ (poY311), connexin-43 (poY265) and Sam68 only under adherent conditions, and p56Dok-2 (poY351) and p120catenin (poY228) only under suspension conditions. In contrast, FAK enhanced the Src-induced phosphorylation of vinculin (poY100 and poY1065) and p130CAS (poY410) irrespective of adherence state, p56Dok-2 (poY351) and p120catenin (poY228) only under adherent conditions, and connexin-43 (poY265), cortactin (poY421) and paxillin (poY31) only under suspension conditions. The Src-induced phosphorylation of Eps8, PLC-γ1 and Shc (poY239/poY240) were not affected by either FAK or adherence status. The enhanced anchorage-independent growth of FAK-/-[v-Src] cells was selectively decreased by expression of paxillinY118F, but not by WT-paxillin, p120cateninY228F or ShcY239/240F, identifying for the first time a role for paxillinpoY118 in Src-induced anchorage-independent growth. Knockdown of FAK by siRNA in the human colon cancer lines HT-25 and RKO, resulted in increased paxillinpoY118 levels under suspension conditions as well as increased anchorage-independent growth, supporting the notion that FAK attenuates anchorage-independent growth by suppressing adhesion-dependent phosphorylation of paxillinY118.ConclusionThese data suggest that phosphorylation of Src substrates is a dynamic process, influenced temporally and spatially by factors such as FAK and adhesion.

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Section: Introductionmentioning

confidence: 99%

“…A further complication is that phosphorylation of some substrates, such as PI3K, varied only under conditions of anchorage independence [30]. Indeed, we demonstrated that the superactivation of PI3K was required and sufficient for the enhanced v-Src-induced anchorage-independent growth of FAK-/- fibroblasts [30]. …”

Section: Introductionmentioning

confidence: 99%

Paxillin-Y118 phosphorylation contributes to the control of Src-induced anchorage-independent growth by FAK and adhesion

Sachdev

Gelman

2009

BMC Cancer

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“…Integrin-dependent PI3K activation has been classically attributed to the binding of activated Src to the p85 subunit of PI3K or from the autophosphorylation of focal adhesion kinase (FAK) on Tyr 397 (22)(23)(24). Recent results suggest that activation of PI3K upon integrin ligation can also occur through other Src-dependent and FAKindependent pathways (25) or via the membrane-proximal part of the ␤1 integrin subunit in a FAK-and Src-independent manner (26). Here we tested the hypothesis that ECM fragments produced by apoptotic EC (and more specifically the LG3 motif of perlecan) interact with integrin receptors on fibroblasts, thus initiating integrin-dependent signaling events leading to the activation of a PI3K-dependent anti-apoptotic and potentially fibrogenic phenotype in fibroblasts.…”

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Perlecan Proteolysis Induces an α2β1 Integrin- and Src Family Kinase-dependent Anti-apoptotic Pathway in Fibroblasts in the Absence of Focal Adhesion Kinase Activation

Laplante

Raymond

Labelle

et al. 2006

Journal of Biological Chemistry

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Dysregulation of apoptosis in endothelial cells (EC) and fibroblasts contributes to fibrosis. We have shown previously that apoptosis of EC triggers the proteolysis of extracellular matrix components and the release of a C-terminal fragment of perlecan, which in turn inhibits apoptosis of fibroblasts. Here we have defined the receptors and pathways implicated in this anti-apoptotic response in fibroblasts. Neutralizing ␣2␤1 integrin activity in fibroblasts exposed to either medium conditioned by apoptotic EC (SSC) or a recombinant perlecan C-terminal fragment (LG3) prevented resistance to apoptosis and is associated with decreased levels of Akt phosphorylation. Co-incubation of fibroblasts for 24 h with SSC or LG3 in the presence of PP2 (AG1879), a biochemical inhibitor of Src family kinases (SFKs) and focal adhesion kinase, showed a significantly decreased anti-apoptotic response. However, focal adhesion kinase gene silencing with RNA interference did not inhibit the anti-apoptotic response in fibroblasts. Src phosphorylation was increased in fibroblasts exposed to SSC, and transfection of fibroblasts with constitutively active Src mutants induced an anti-apoptotic response that was not further increased by SSC. Also, Src ؊/؊ Fyn ؊/؊ fibroblasts failed to mount an anti-apoptotic response in presence of SSC for 24 h but developed a complete anti-apoptotic response when exposed to SSC for 7 days. These results suggest that extracellular matrix fragments produced by apoptotic EC initiate a state of resistance to apoptosis in fibroblasts via an ␣2␤1 integrin/SFK (Src and Fyn)/phosphatidylinositol 3-kinase (PI3K)-dependent pathway. In the long term, additional SFK members are recruited for sustaining the anti-apoptotic response, which could play crucial roles in abnormal fibrogenic healing.

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“…However, in breast cancer cells, the relevance and dispensability of each member of this complex is not fully understood, and it is still intriguing the importance of their kinase activity and their role as adaptor proteins to control the signaling pathways they trigger. A recent work in mouse embryo fibroblasts showed that Fak is dispensable for v-Src-induced transformation but would exert either positive or negative effects on signaling or motility depending on the pathways activated (6).…”

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Role of c-Src in Human MCF7 Breast Cancer Cell Tumorigenesis

González

Agulló-Ortuño

García-Martínez

et al. 2006

Journal of Biological Chemistry

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To study the role of c-Src in breast cancer tumorigenesis, we generated a cell line derived from MCF7 carrying an inducible dominant negative c-Src (c-SrcDN: K295M/Y527F) under tetracycline control (Tet-On system). c-SrcDN expression caused phenotypic changes, relocation of c-Src, Fak, and paxillin, and loss of correct actin fiber assembly. These alterations were coupled to increased Fak-Tyr 397 autophosphorylation and to inhibition of Fak-Tyr 925 , p130 CAS , and paxillin phosphorylation. An increased association of total Src with Fak and a decreased interaction of p130 CAS and p85-PI3K with Fak were also observed. SrcDN inhibited cell attachment, spreading, and migration. Serum and EGF-induced stimulation of cell proliferation and Akt phosphorylation were also significantly reduced by SrcDN, whereas p27Kip1 expression was increased. Consistently, silencing c-Src expression by siRNA in MCF7 cells significantly reduced cell migration, attachment, spreading and proliferation. Inoculation of MCF7 cells carrying inducible SrcDN to nude mice generated tumors. However, doxycycline administration to mice significantly reduced tumorigenesis, and when doxycycline treatment was installed after tumor development, a significant tumor regression was observed. In both situations, inhibition of tumorigenesis was associated with decreased Ki67 staining and increased apoptosis in tumors. These data undoubtedly demonstrate the relevance of the Src/Fak complex in breast cancer tumorigenesis.

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Enhanced v-Src-induced oncogenic transformation in the absence of focal adhesion kinase is mediated by phosphatidylinositol 3-kinase

Cited by 12 publications

References 55 publications

Paxillin-Y118 phosphorylation contributes to the control of Src-induced anchorage-independent growth by FAK and adhesion

Paxillin-Y118 phosphorylation contributes to the control of Src-induced anchorage-independent growth by FAK and adhesion

Perlecan Proteolysis Induces an α2β1 Integrin- and Src Family Kinase-dependent Anti-apoptotic Pathway in Fibroblasts in the Absence of Focal Adhesion Kinase Activation

Role of c-Src in Human MCF7 Breast Cancer Cell Tumorigenesis

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