scholarly journals Cancer-associated mutations in the p85α N-terminal SH2 domain activate a spectrum of receptor tyrosine kinases

2021 ◽  
Vol 118 (37) ◽  
pp. e2101751118
Author(s):  
Xinran Li ◽  
Amy Y. T. Lau ◽  
Angel S. N. Ng ◽  
Abdullah Aldehaiman ◽  
Yuan Zhou ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Sh2 Domain ◽  
Regulatory Subunit ◽  
Driver Mutations ◽  
Akt Pathway ◽  
Independent Manner ◽  
Inhibitory Interaction ◽  
Her Family ◽  
Protein Levels ◽  
Phosphoinositide 3 Kinase

The phosphoinositide 3-kinase regulatory subunit p85α is a key regulator of kinase signaling and is frequently mutated in cancers. In the present study, we showed that in addition to weakening the inhibitory interaction between p85α and p110α, a group of driver mutations in the p85α N-terminal SH2 domain activated EGFR, HER2, HER3, c-Met, and IGF-1R in a p110α-independent manner. Cancer cells expressing these mutations exhibited the activation of p110α and the AKT pathway. Interestingly, the activation of EGFR, HER2, and c-Met was attributed to the ability of driver mutations to inhibit HER3 ubiquitination and degradation. The resulting increase in HER3 protein levels promoted its heterodimerization with EGFR, HER2, and c-Met, as well as the allosteric activation of these dimerized partners; however, HER3 silencing abolished this transactivation. Accordingly, inhibitors of either AKT or the HER family reduced the oncogenicity of driver mutations. The combination of these inhibitors resulted in marked synergy. Taken together, our findings provide mechanistic insights and suggest therapeutic strategies targeting a class of recurrent p85α mutations.

scholarly journals v-Crk Activates the Phosphoinositide 3-Kinase/AKT Pathway by Utilizing Focal Adhesion Kinase and H-Ras

2002 ◽  
Vol 22 (20) ◽  
pp. 7015-7023 ◽  
Author(s):  
Tsuyoshi Akagi ◽  
Kazutaka Murata ◽  
Tomoyuki Shishido ◽  
Hidesaburo Hanafusa
Keyword(s):  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Critical Role ◽  
Sh3 Domain ◽  
Sh2 Domain ◽  
Dominant Negative ◽  
Regulatory Subunit ◽  
Akt Pathway ◽  
Dominant Negative Mutant ◽  
Phosphoinositide 3 Kinase

ABSTRACT v-Crk, an oncogene product of avian sarcoma virus CT10, efficiently transforms chicken embryo fibroblasts (CEF). We have recently reported that constitutive activation of the phosphoinositide 3-kinase (PI3K)/AKT pathway plays a critical role in the v-Crk-induced transformation of CEF. In the present study we investigated the molecular mechanism by which v-Crk activates the PI3K/AKT pathway. First, we found that v-Crk promotes the association of the p85 regulatory subunit of PI3K with focal adhesion kinase (FAK) by inducing the phosphorylation of the Y397 residue in FAK. This FAK phosphorylation needs activation of the Src family tyrosine kinase(s) for which the v-Crk SH2 domain is responsible. v-Crk was unable to activate the PI3K/AKT pathway in FAK-null cells, indicating the functional importance of FAK. In addition, we found that H-Ras is also required for the activation of the PI3K/AKT pathway. The v-Crk-induced activation of AKT was greatly enhanced by the overexpression of H-Ras or its guanine nucleotide exchange factor mSOS, which binds to the v-Crk SH3 domain, whereas a dominant-negative mutant of H-Ras almost completely suppressed this activation. Furthermore, we showed that v-Crk stimulates the interaction of H-Ras with the Ras binding domain in the PI3K p110 catalytic subunit. Our data indicated that the v-Crk-induced activation of PI3K/AKT pathway was cooperatively achieved by two distinct interactions. One is the interaction of p85 with tyrosine-phosphorylated FAK promoted by the v-Crk SH2 domain, and another is the interaction of p110 with H-Ras dictated by the v-Crk SH3 domain.

FOXD3 inhibits cell proliferation, migration, and invasion in nasopharyngeal carcinoma through regulation of the PI3K–Akt pathway

2020 ◽  
Vol 98 (6) ◽  
pp. 653-660 ◽  
Author(s):  
Xiaoxing Xie ◽  
Gaoyun Xiong ◽  
Wenjun Chen ◽  
Hongdan Fu ◽  
Mingqian Li ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Nasopharyngeal Carcinoma ◽  
Cell Apoptosis ◽  
Inhibitory Effect ◽  
Akt Pathway ◽  
Migration And Invasion ◽  
Inhibitory Effects ◽  
Protein Levels ◽  
Flow Cytometric ◽  
Phosphoinositide 3 Kinase

FOXD3 has been found previously to positively regulate miR-26b, a tumor inhibitor of nasopharyngeal carcinoma (NPC). However, FOXD3’s precise function and associated mechanism of action in NPC have not yet been investigated. In this study, the expression of FOXD3 mRNA and protein was evaluated using RT-qPCR, western blotting, and immunohistochemistry. Protein levels involved in the phosphoinositide 3-kinase – protein kinase B (PI3K–Akt) pathway were assessed by western blot, and cell proliferation was determined by MTT and colony forming assays. Additionally, cell apoptosis was assessed by flow cytometric assay. Finally, the migration and invasion capabilities of the NPC cells were determined using wound healing and Transwell assays. We found that FOXD3 levels were relatively low in NPC tissue and cells, while an increase caused the inhibition of the PI3K–Akt pathway. Functional experiments found that overexpression of FOXD3 suppressed cell proliferation, migration, and invasion and enhanced cell apoptosis in NPC C6661 cells. IGF-1, an activator of the PI3K–Akt pathway, reversed the inhibitory effect of FOXD3. Furthermore, we found upregulation of the PI3K–Akt pathway and upregulation of the inhibitory effects of FOXD3 on C6661 cellular activities. In conclusion, FOXD3 negatively affected the PI3K–Akt pathway to restrain the processes involved in C6661 cell pathology. These findings further exposed the function and downstream axis of FOXD3 in NPC and displayed a promising new target for NPC therapy.

scholarly journals Ephrin-independent regulation of cell substrate adhesion by the EphB4 receptor

2009 ◽  
Vol 422 (3) ◽  
pp. 433-442 ◽  
Author(s):  
Nicole K. Noren ◽  
Nai-Ying Yang ◽  
Morgan Silldorff ◽  
Ravi Mutyala ◽  
Elena B. Pasquale
Keyword(s):  
Cancer Cells ◽  
Tyrosine Kinases ◽  
Single Amino Acid ◽  
Cell Contact ◽  
Eph Receptors ◽  
Independent Manner ◽  
Protein Levels ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Cell Substrate Adhesion

Receptor tyrosine kinases of the Eph family become tyrosine phosphorylated and initiate signalling events upon binding of their ligands, the ephrins. Eph receptors such as EphA2 and EphB4 are highly expressed but poorly tyrosine phosphorylated in many types of cancer cells, suggesting a limited interaction with ephrin ligands. Nevertheless, decreasing the expression of these receptors affects the malignant properties of cancer cells, suggesting that Eph receptors may influence cancer cells independently of ephrin stimulation. Ligand-independent activities of Eph receptors in cancer, however, have not been demonstrated. By using siRNA (small interfering RNA) to downregulate EphB4 in MCF7 and MDA-MB-435 cancer cells, we found that EphB4 inhibits integrin-mediated cell substrate adhesion, spreading and migration, and reduces β1-integrin protein levels. Low expression of the EphB4 preferred ligand, ephrin-B2, and minimal contact between cells in these assays suggest that cell contact-dependent stimulation of EphB4 by the transmembrane ephrin-B2 ligand does not play a role in these effects. Indeed, inhibitors of ephrin-B2 binding to endogenous EphB4 did not influence cell substrate adhesion. Increasing EphB4 expression by transient transfection inhibited cell substrate adhesion, and this effect was also independent of ephrin stimulation because it was not affected by single amino acid mutations in EphB4 that impair ephrin binding. The overexpressed EphB4 was tyrosine phosphorylated, and we found that EphB4 kinase activity is important for inhibition of integrin-mediated adhesion, although several EphB4 tyrosine phosphorylation sites are dispensable. These findings demonstrate that EphB4 can affect cancer cell behaviour in an ephrin-independent manner.

scholarly journals Small GTPases and tyrosine kinases coregulate a molecular switch in the phosphoinositide 3-kinase regulatory subunit

Cancer Cell ◽  
2002 ◽  
Vol 1 (2) ◽  
pp. 181-191 ◽  
Author(s):  
Tung O. Chan ◽  
Ulrich Rodeck ◽  
Andrew M. Chan ◽  
Alec C. Kimmelman ◽  
Susan E. Rittenhouse ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Molecular Switch ◽  
Small Gtpases ◽  
Regulatory Subunit ◽  
Phosphoinositide 3 Kinase

scholarly journals Lactate Engages Receptor Tyrosine Kinases Axl, Tie2, and Vascular Endothelial Growth Factor Receptor 2 to Activate Phosphoinositide 3-Kinase/Akt and Promote Angiogenesis

2013 ◽  
Vol 288 (29) ◽  
pp. 21161-21172 ◽  
Author(s):  
Guo-Xiang Ruan ◽  
Andrius Kazlauskas
Keyword(s):  
Endothelial Cells ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Growth Factor Receptor ◽  
Akt Pathway ◽  
Vegf Receptor ◽  
Vascular Perfusion ◽  
Phosphoinositide 3 Kinase ◽  
High Level ◽  
Aortic Explants

Although a high level of lactate is quintessential to both tumors and wound healing, the manner by which lactate impacts endothelial cells to promote angiogenesis and thereby create or restore vascular perfusion to growing tissues has not been fully elucidated. Here we report that lactate activated the PI3K/Akt pathway in primary human endothelial cells. Furthermore, activating this signaling pathway was required for lactate-stimulated organization of endothelial cells into tubes and for sprouting of vessels from mouse aortic explants. Lactate engaged the PI3K/Akt pathway via ligand-mediated activation of the three receptor tyrosine kinases Axl, Tie2, and VEGF receptor 2. Neutralizing the ligands for these receptor tyrosine kinases, pharmacologically inhibiting their kinase activity or suppressing their expression largely eliminated the ability of cells and explants to respond to lactate. Elucidating the mechanism by which lactate communicates with endothelial cells presents a previously unappreciated opportunity to improve our understanding of the angiogenic program and to govern it.

Solution structure of the C-terminal SH2 domain of the p85α regulatory subunit of phosphoinositide 3-kinase 1 1Edited by P. E. Wright

1998 ◽  
Vol 276 (2) ◽  
pp. 461-478 ◽  
Author(s):  
Gregg Siegal ◽  
Ben Davis ◽  
Søren M. Kristensen ◽  
Andrew Sankar ◽  
Jeffrey Linacre ◽  
...  
Keyword(s):  
Solution Structure ◽  
Sh2 Domain ◽  
Regulatory Subunit ◽  
Phosphoinositide 3 Kinase

scholarly journals Structural insights into phosphoinositide 3-kinase activation by the influenza A virus NS1 protein

2010 ◽  
Vol 107 (5) ◽  
pp. 1954-1959 ◽  
Author(s):  
Benjamin G. Hale ◽  
Philip S. Kerry ◽  
David Jackson ◽  
Bernard L. Precious ◽  
Alexander Gray ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Coiled Coil ◽  
Sh2 Domain ◽  
Regulatory Subunit ◽  
Ns1 Protein ◽  
Influenza A Viruses ◽  
Phosphoinositide 3 Kinase ◽  
Α Helix

Seasonal epidemics and periodic worldwide pandemics caused by influenza A viruses are of continuous concern. The viral nonstructural (NS1) protein is a multifunctional virulence factor that antagonizes several host innate immune defenses during infection. NS1 also directly stimulates class IA phosphoinositide 3-kinase (PI3K) signaling, an essential cell survival pathway commonly mutated in human cancers. Here, we present a 2.3-Å resolution crystal structure of the NS1 effector domain in complex with the inter-SH2 (coiled-coil) domain of p85β, a regulatory subunit of PI3K. Our data emphasize the remarkable isoform specificity of this interaction, and provide insights into the mechanism by which NS1 activates the PI3K (p85β:p110) holoenzyme. A model of the NS1:PI3K heterotrimeric complex reveals that NS1 uses the coiled-coil as a structural tether to sterically prevent normal inhibitory contacts between the N-terminal SH2 domain of p85β and the p110 catalytic subunit. Furthermore, in this model, NS1 makes extensive contacts with the C2/kinase domains of p110, and a small acidic α-helix of NS1 sits adjacent to the highly basic activation loop of the enzyme. During infection, a recombinant influenza A virus expressing NS1 with charge-disruption mutations in this acidic α-helix is unable to stimulate the production of phosphatidylinositol 3,4,5-trisphosphate or the phosphorylation of Akt. Despite this, the charge-disruption mutations in NS1 do not affect its ability to interact with the p85β inter-SH2 domain in vitro. Overall, these data suggest that both direct binding of NS1 to p85β (resulting in repositioning of the N-terminal SH2 domain) and possible NS1:p110 contacts contribute to PI3K activation.

scholarly journals Deficiency in the p110α subunit of PI3K results in diminished Tie2 expression and Tie2-/-–like vascular defects in mice

Blood ◽  
2005 ◽  
Vol 105 (10) ◽  
pp. 3935-3938 ◽  
Author(s):  
Etienne Lelievre ◽  
Pierre-Marie Bourbon ◽  
Li-Juan Duan ◽  
Robert L. Nussbaum ◽  
Guo-Hua Fong
Keyword(s):  
Tyrosine Kinases ◽  
Branching Morphogenesis ◽  
Vascular Endothelial ◽  
Mouse Development ◽  
Protein Levels ◽  
Upstream Regulator ◽  
Phosphoinositide 3 Kinase ◽  
Endothelial Growth Factor

AbstractPhosphoinositide 3-kinase (PI3K) is activated by transmembrane tyrosine kinases such as vascular endothelial growth factor (VEGF) receptors and Tie2 (tunica intima endothelial kinase 2), both of which are key regulators of vascular development. However, the in vivo role of PI3K during developmental vascularization remains to be defined. Here we demonstrate that mice deficient in the p110α catalytic subunit of PI3K display multiple vascular defects, including dilated vessels in the head, reduced branching morphogenesis in the endocardium, lack of hierarchical order of large and small branches in the yolk sac, and impaired development of anterior cardinal veins. These vascular defects are strikingly similar to those in mice defective in the Tie2 signaling pathway. Indeed, Tie2 protein levels were significantly lower in p110α-deficient mice. Furthermore, RNA interference of p110α in cultured endothelial cells significantly reduced Tie2 protein levels. These findings raise the possibility that PI3K may function as an upstream regulator of Tie2 expression during mouse development.

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