scholarly journals Regulation of PI3K effector signalling in cancer by the phosphoinositide phosphatases

2017 ◽  
Vol 37 (1) ◽  
Author(s):  
Samuel J. Rodgers ◽  
Daniel T. Ferguson ◽  
Christina A. Mitchell ◽  
Lisa M. Ooms
Keyword(s):  
Cell Growth ◽  
Human Cancer ◽  
Pi3k Pathway ◽  
Inositol Polyphosphate ◽  
Ph Domain ◽  
Akt Activation ◽  
Signalling Molecules ◽  
Akt Isoforms ◽  
Breast And Prostate Cancer ◽  
Phosphoinositide 3 Kinase

Class I phosphoinositide 3-kinase (PI3K) generates phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) at the plasma membrane in response to growth factors, activating a signalling cascade that regulates many cellular functions including cell growth, proliferation, survival, migration and metabolism. The PI3K pathway is commonly dysregulated in human cancer, and drives tumorigenesis by promoting aberrant cell growth and transformation. PtdIns(3,4,5)P3 facilitates the activation of many pleckstrin homology (PH) domain-containing proteins including the serine/threonine kinase AKT. There are three AKT isoforms that are frequently hyperactivated in cancer through mutation, amplification or dysregulation of upstream regulatory proteins. AKT isoforms have converging and opposing functions in tumorigenesis. PtdIns(3,4,5)P3 signalling is degraded and terminated by phosphoinositide phosphatases such as phosphatase and tensin homologue (PTEN), proline-rich inositol polyphosphate 5-phosphatase (PIPP) (INPP5J) and inositol polyphosphate 4-phosphatase type II (INPP4B). PtdIns(3,4,5)P3 is rapidly hydrolysed by PIPP to generate phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P2), which is further hydrolysed by INPP4B to form phosphatidylinositol 3-phosphate (PtdIns3P). PtdIns(3,4)P2 and PtdIns3P are also important signalling molecules; PtdIns(3,4)P2 together with PtdIns(3,4,5)P3 are required for maximal AKT activation and PtdIns3P activates PI3K-dependent serum and glucocorticoid-regulated kinase (SGK3) signalling. Loss of Pten, Pipp or Inpp4b expression or function promotes tumour growth in murine cancer models through enhanced AKT isoform-specific signalling. INPP4B inhibits PtdIns(3,4)P2-mediated AKT activation in breast and prostate cancer; however, INPP4B expression is increased in acute myeloid leukaemia (AML), melanoma and colon cancer where it paradoxically promotes cell proliferation, transformation and/or drug resistance. This review will discuss how PTEN, PIPP and INPP4B distinctly regulate PtdIns(3,4,5)P3 signalling downstream of PI3K and how dysregulation of these phosphatases affects cancer outcomes.

Akt is efficiently activated by PIF-pocket- and PtdIns(3,4,5)P3-dependent mechanisms leading to resistance to PDK1 inhibitors

2012 ◽  
Vol 448 (2) ◽  
pp. 285-295 ◽  
Author(s):  
Ayaz Najafov ◽  
Natalia Shpiro ◽  
Dario R. Alessi
Keyword(s):  
Cell Lines ◽  
Therapeutic Strategy ◽  
Mammalian Target Of Rapamycin ◽  
Significant Proportion ◽  
Mtor Inhibitors ◽  
Akt Activation ◽  
Akt Isoforms ◽  
Anti Cancer ◽  
Phosphoinositide 3 Kinase ◽  
Loop Residue

Mutations leading to inappropriate activation of Akt isoforms contribute to proliferation and survival of a significant proportion of human cancers. Akt is activated by phosphorylation of its T-loop residue (Thr308) by PDK1 (3-phosphoinositide-dependent kinase-1) and its C-terminal hydrophobic motif (Ser473) by mTORC2 [mTOR (mammalian target of rapamycin) complex 2]. Potent PDK1 inhibitors such as GSK2334470 have recently been elaborated as potential anti-cancer agents. However, these compounds were surprisingly ineffective at suppressing Akt activation. In the present study we demonstrate that resistance to PDK1 inhibitors results from Akt being efficiently recruited to PDK1 via two alternative mechanisms. The first involves ability of Akt and PDK1 to mutually interact with the PI3K (phosphoinositide 3-kinase) second messenger PtdIns(3,4,5)P3. The second entails recruitment of PDK1 to Akt after its phosphorylation at Ser473 by mTORC2, via a substrate-docking motif termed the PIF-pocket. We find that disruption of either the PtdIns(3,4,5)P3 or the Ser473 phosphorylation/PIF-pocket mechanism only moderately impacts on Akt activation, but induces marked sensitization to PDK1 inhibitors. These findings suggest that suppression of Ser473 phosphorylation by using mTOR inhibitors would disrupt the PIF-pocket mechanism and thereby sensitize Akt to PDK1 inhibitors. Consistent with this, we find combing PDK1 and mTOR inhibitors reduced Akt activation to below basal levels and markedly inhibited proliferation of all of the cell lines tested. Our results suggest further work is warranted to explore the utility of combining PDK1 and mTOR inhibitors as a therapeutic strategy for treatment of cancers that harbour mutations elevating Akt activity.

Chemically targeting the PI3K family

2007 ◽  
Vol 35 (2) ◽  
pp. 245-249 ◽  
Author(s):  
Z.A. Knight ◽  
K.M. Shokat
Keyword(s):  
Cell Growth ◽  
Recent Progress ◽  
Pi3k Pathway ◽  
Selective Inhibitors ◽  
Growth Metabolism ◽  
Phosphoinositide 3 Kinase ◽  
Widespread Interest

PI3K (phosphoinositide 3-kinase) is a key regulator of cell growth, metabolism and survival. The frequent activation of the PI3K pathway in cancer has stimulated widespread interest in identifying potent and selective inhibitors of PI3K isoforms. The present paper highlights recent progress in identifying such molecules and the challenges that remain for efforts to pharmacologically target the PI3K family.

scholarly journals The Type Iα Inositol Polyphosphate 4-Phosphatase Generates and Terminates Phosphoinositide 3-Kinase Signals on Endosomes and the Plasma Membrane

2005 ◽  
Vol 16 (5) ◽  
pp. 2218-2233 ◽  
Author(s):  
Ivan Ivetac ◽  
Adam D. Munday ◽  
Marina V. Kisseleva ◽  
Xiang-Ming Zhang ◽  
Susan Luff ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Effector Proteins ◽  
Type I ◽  
Endosomal Trafficking ◽  
Inositol Polyphosphate ◽  
Ph Domain ◽  
Membrane Recruitment ◽  
Early Endosomes ◽  
Phosphoinositide 3 Kinase

Endosomal trafficking is regulated by the recruitment of effector proteins to phosphatidylinositol 3-phosphate [PtdIns(3)P] on early endosomes. At the plasma membrane, phosphatidylinositol-(3,4)-bisphosphate [PtdIns(3,4)P2] binds the pleckstrin homology (PH) domain-containing proteins Akt and TAPP1. Type Iα inositol polyphosphate 4-phosphatase (4-phosphatase) dephosphorylates PtdIns(3,4)P2, forming PtdIns(3)P, but its subcellular localization is unknown. We report here in quiescent cells, the 4-phosphatase colocalized with early and recycling endosomes. On growth factor stimulation, 4-phosphatase endosomal localization persisted, but in addition the 4-phosphatase localized at the plasma membrane. Overexpression of the 4-phosphatase in serum-stimulated cells increased cellular PtdIns(3)P levels and prevented wortmannin-induced endosomal dilatation. Furthermore, mouse embryonic fibroblasts from homozygous Weeble mice, which have a mutation in the type I 4-phosphatase, exhibited dilated early endosomes. 4-Phosphatase translocation to the plasma membrane upon growth factor stimulation inhibited the recruitment of the TAPP1 PH domain. The 4-phosphatase contains C2 domains, which bound PtdIns(3,4)P2, and C2-domain-deletion mutants lost PtdIns(3,4)P2 4-phosphatase activity, did not localize to endosomes or inhibit TAPP1 PH domain membrane recruitment. The 4-phosphatase therefore both generates and terminates phosphoinositide 3-kinase signals at distinct subcellular locations.

Tyrosine phosphorylation of B-cell adaptor for phosphoinositide 3-kinase is required for Akt activation in response to CD19 engagement

Blood ◽  
2002 ◽  
Vol 99 (2) ◽  
pp. 584-589 ◽  
Author(s):  
Kazunori Inabe ◽  
Tomohiro Kurosaki
Keyword(s):  
B Cell ◽  
Binding Site ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Pi3k Pathway ◽  
Cross Linking ◽  
B Cell Antigen Receptor ◽  
Akt Activation ◽  
Adaptor Molecule ◽  
Phosphoinositide 3 Kinase

Abstract CD19 is a coreceptor that amplifies signaling initiated by antigen cross-linking of the B-cell antigen receptor (BCR). CD19 can also signal independently of BCR coligation. This study shows thatB-cell adaptor forphosphoinositide 3-kinase (BCAP), previously characterized as a substrate of the tyrosine kinases upon BCR engagement, is phosphorylated by cross-linking of CD19. Tyrosine phosphorylation of BCAP, mediated by Lyn, provides binding site(s) for phosphoinositide 3-kinase (PI3K), thereby participating in Akt activation. Thus, these results provide evidence that BCAP serves as an adaptor molecule for CD19 to activate the PI3K pathway in B cells.

Pharmacoinformatic Approaches to Design Novel Inhibitors of Protein Kinase B Pathways in Cancer

2018 ◽  
Vol 18 (9) ◽  
pp. 830-846
Author(s):  
Noreen Akhtar ◽  
Ishrat Jabeen
Keyword(s):  
Amino Acid ◽  
Protein Kinase ◽  
Cell Growth ◽  
Human Cancer ◽  
Clinical Investigation ◽  
Protein Kinase B ◽  
Chemotherapeutic Agents ◽  
Amino Acid Residues ◽  
Ph Domain ◽  
Selective Inhibitors

Background: Protein kinase B (PKB/Akt) belongs to the AGC superfamily of related serine/ threonine kinases with three structurally homologous mammalian isoforms, Akt1 (PKBα), Akt2 (PKBβ), and Akt3 (PKBγ). Besides sharing a similar structural topology, the difference in their physiological functions and tissue distribution makes Akt a cardinal node in diverse signaling pathways involving cell growth, survival, and proliferation. Various immunohistochemical studies have reported that the constitutive hyperactivation of Akt signaling is responsible for several types of human cancer, poor prognosis, as well as chemotherapeutic and radiotherapeutic resistance. Thus, inhibition of Akt activation represents a promising concept to induce cell apoptosis in various cancers and evade chemotherapeutic resistance. However, development of potent and selective inhibitors of Akt kinases as suitable antagonists remained gloomy and thus, only handful of compounds were selected for the clinical investigation but none of them could reach the market for routine clinical usage to circumvent cell proliferation and resistance to chemotherapeutic agents in cancer. Recent reports on achieving isoform selectivity by designing inhibitors against PH domain of Akt, together with availability of crystal structures of the PH domain of Akt1, open the possibility of structurebased design. Methods: In this article, various biological regulatory networks by which Akt and its substrates regulate cell growth and survival and several SAR and QSAR strategies in combination with molecular docking studies on selective inhibitors of Akt subtypes have been highlighted to further probe the selectivity of ligand-Akt subtypes interactions. Results: Structure-based drug design studies revealed that the interactions of structurally diverse compounds with Glu121, Ala123, Asn171, Asp184, Glu228 and Ala230 amino acid residues in CAT domain and Arg23, Arg25, Lys30, Asn54 and Arg86 amino acid residues within PH domain play an important role in attaining significant inhibitory potency. Conclusion: Isoform selective inhibition of Akt might have clinical significance and thus, should be taken into account in future investigations. Moreover, an up to date isoform selective chemical data is required to further validate already reported isoform selective binding hypothesis.

Platelet-Rich and Platelet-Poor Plasma Might Play Supportive Roles in Cancer Cell Culture: A Replacement for Fetal Bovine Serum?

2021 ◽  
Vol 21 ◽  
Author(s):  
Mehdi Talebi ◽  
Mousa Vatanmakanian ◽  
Ali Mirzaei ◽  
Yaghoub Barfar ◽  
Maryam Hemmatzadeh ◽  
...  
Keyword(s):  
Cell Culture ◽  
Cell Growth ◽  
Cancer Cell ◽  
Human Cancer ◽  
High Price ◽  
Dependent Manner ◽  
Platelet Poor Plasma ◽  
Protein Levels ◽  
Healthy Donors ◽  
Regulatory Functions

Background: Platelet-rich (PRP) and Platelet-poor plasma (PPP) are widely used in research and clinical platforms mainly due to their capacities to enhance cell growth. Although short half-life (5 days) and the high price of platelet products pose challenges regarding their usage, they maintain the growth regulatory functions for weeks. Thus, we aimed to assess the supplementary values of these products in human CCRF-CEM cancer cells. Mechanistically, we also checked if the PRP/PPP treatment enhances YKL-40 expression as a known protein regulating cell growth. Methods: The PRP/PPP was prepared from healthy donors using manual stepwise centrifugation and phase separation. The viability of the cells treated with gradient PRP/PPP concentrations (2, 5, 10, and 15%) was measured by the MTT assay. The YKL-40 mRNA and protein levels were assessed using qRT-PCR and western blotting. The data were compared to FBS-treated cells. Result: Our findings revealed that the cells treated by PRP/PPP not only were morphologically comparable to those treated by FBS but also, they showed greater viability at the concentrations of 10 and 15%. Moreover, it was shown that PRP/PPP induce cell culture support, at least in part, via inducing YKL-40 expression at both mRNA and protein levels in a time- and dose-dependent manner. Conclusion: Collectively, by showing cell culture support comparable to FBS, the PRP/PPP might be used as good candidates to supplement the cancer cell culture and overcome concerns regarding the use of FBS as a non-human source in human cancer research.

scholarly journals Arginine Methyltransferase PRMT1 Regulates p53 Activity in Breast Cancer

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 789
Author(s):  
Li-Ming Liu ◽  
Qiang Tang ◽  
Xin Hu ◽  
Jing-Jing Zhao ◽  
Yuan Zhang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Growth ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Asymmetric Dimethylarginine ◽  
Human Cancer ◽  
Specific Inhibitor ◽  
Dependent Manner ◽  
Breast Tumorigenesis ◽  
Stress Signals

The protein p53 is one of the most important tumor suppressors, responding to a variety of stress signals. Mutations in p53 occur in about half of human cancer cases, and dysregulation of the p53 function by epigenetic modifiers and modifications is prevalent in a large proportion of the remainder. PRMT1 is the main enzyme responsible for the generation of asymmetric-dimethylarginine, whose upregulation or aberrant splicing has been observed in many types of malignancies. Here, we demonstrate that p53 function is regulated by PRMT1 in breast cancer cells. PRMT1 knockdown activated the p53 signal pathway and induced cell growth-arrest and senescence. PRMT1 could directly bind to p53 and inhibit the transcriptional activity of p53 in an enzymatically dependent manner, resulting in a decrease in the expression levels of several key downstream targets of the p53 pathway. We were able to detect p53 asymmetric-dimethylarginine signals in breast cancer cells and breast cancer tissues from patients, and the signals could be significantly weakened by silencing of PRMT1 with shRNA, or inhibiting PRMT1 activity with a specific inhibitor. Furthermore, PRMT1 inhibitors significantly impeded cell growth and promoted cellular senescence in breast cancer cells and primary tumor cells. These results indicate an important role of PRMT1 in the regulation of p53 function in breast tumorigenesis.

scholarly journals Phosphoinositide 3-Kinase-Dependent Inhibition of Dendritic Cell Interleukin-12 Production by Giardia lamblia

2008 ◽  
Vol 77 (2) ◽  
pp. 685-693 ◽  
Author(s):  
Joel Désiré Kamda ◽  
Steven M. Singer
Keyword(s):  
Dendritic Cell ◽  
Giardia Lamblia ◽  
Pi3k Pathway ◽  
Interleukin 12 ◽  
Adaptive Responses ◽  
Necrosis Factor Alpha ◽  
Murine Bone Marrow ◽  
Mechanism Of Inhibition ◽  
Enhanced Secretion ◽  
Phosphoinositide 3 Kinase

ABSTRACT Dendritic cell interactions with pathogenic microbes initiate and direct the development of subsequent adaptive responses. The protozoan pathogen Giardia lamblia infects the mammalian small intestine, leading to nutrient malabsorption and diarrhea but rarely causing inflammation. In order to begin to understand how the innate immune system responds to this parasite and shapes the eventual adaptive response, we examined the interaction between parasites and murine bone marrow-derived dendritic cells (DCs). DCs incubated with live parasites or parasite extracts displayed enhanced levels of CD40. The expression of CD80 and CD86 also increased, but less than was seen with lipopolysaccharide-activated DCs. Small amounts of interleukin-6 (IL-6) and tumor necrosis factor alpha were secreted by these DCs, whereas no IL-10 or IL-12 could be detected. Coincubation of DCs with parasite extracts along with known Toll-like receptor (TLR) ligands resulted in enhanced secretion of IL-10 and reduced secretion of IL-12. The levels of major histocompatibility complex class II, CD80, and CD86 were also reduced compared to DCs stimulated with TLR ligands alone. Finally, studies with an extracellular signal-regulated kinase 1/2 pathway inhibitor, a phosphoinositide 3-kinase (PI3K) inhibitor, and anti-IL-10 receptor antibody revealed that the PI3K pathway is the dominant mechanism of inhibition in DCs incubated with both lipopolysaccharide and Giardia. These data suggest that this parasite actively interferes with host innate immunity, resulting in an immune response able to control the infection but devoid of strong inflammatory signals.

scholarly journals Akt isoforms differentially regulate neutrophil functions

Blood ◽  
2010 ◽  
Vol 115 (21) ◽  
pp. 4237-4246 ◽  
Author(s):  
Jia Chen ◽  
Haiyang Tang ◽  
Nissim Hay ◽  
Jingsong Xu ◽  
Richard D. Ye
Keyword(s):  
Kinase Inhibitor ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Leading Edge ◽  
Neutrophil Activation ◽  
Enzyme Release ◽  
Wild Type ◽  
Akt Isoforms ◽  
Phosphoinositide 3 Kinase ◽  
O2 Production

In neutrophils, the phosphoinositide 3-kinase/Akt signaling cascade is involved in migration, degranulation, and O2− production. However, it is unclear whether the Akt kinase isoforms have distinct functions in neutrophil activation. Here we report functional differences between the 2 major Akt isoforms in neutrophil activation on the basis of studies in which we used individual Akt1 and Akt2 knockout mice. Akt2−/− neutrophils exhibited decreased cell migration, granule enzyme release, and O2− production compared with wild-type and Akt1−/− neutrophils. Surprisingly, Akt2 deficiency and pharmacologic inhibition of Akt also abrogated phorbol ester-induced O2− production, which was unaffected by treatment with the phosphoinositide 3-kinase inhibitor LY294002. The decreased O2− production in Akt2−/− neutrophils was accompanied by reduced p47phox phosphorylation and its membrane translocation, suggesting that Akt2 is important for the assembly of phagocyte nicotinamide adenine dinucleotide phosphate oxidase. In wild-type neutrophils, Akt2 but not Akt1 translocated to plasma membrane upon chemoattractant stimulation and to the leading edge in polarized neutrophils. In the absence of Akt2, chemoattractant-induced Akt protein phosphorylation was significantly reduced. These results demonstrate a predominant role of Akt2 in regulating neutrophil functions and provide evidence for differential activation of the 2 Akt isoforms in neutrophils.

scholarly journals Nuclear FOXO1 promotes lymphomagenesis in germinal center B cells

Blood ◽  
2018 ◽  
Vol 132 (25) ◽  
pp. 2670-2683 ◽  
Author(s):  
Eleni Kabrani ◽  
Van Trung Chu ◽  
Evangelia Tasouri ◽  
Thomas Sommermann ◽  
Kevin Baßler ◽  
...  
Keyword(s):  
B Cell ◽  
Germinal Center ◽  
Transcriptional Activity ◽  
Tumor Development ◽  
Pi3k Pathway ◽  
Forkhead Box ◽  
Nuclear Exclusion ◽  
Pi3k Activation ◽  
Phosphoinositide 3 Kinase ◽  
Human And Mouse

Abstract Forkhead box class O1 (FOXO1) acts as a tumor suppressor in solid tumors. The oncogenic phosphoinositide-3-kinase (PI3K) pathway suppresses FOXO1 transcriptional activity by enforcing its nuclear exclusion upon AKT-mediated phosphorylation. We show here abundant nuclear expression of FOXO1 in Burkitt lymphoma (BL), a germinal center (GC) B-cell–derived lymphoma whose pathogenesis is linked to PI3K activation. Recurrent FOXO1 mutations, which prevent AKT targeting and lock the transcription factor in the nucleus, are used by BL to circumvent mutual exclusivity between PI3K and FOXO1 activation. Using genome editing in human and mouse lymphomas in which MYC and PI3K cooperate synergistically in tumor development, we demonstrate proproliferative and antiapoptotic activity of FOXO1 in BL and identify its nuclear localization as an oncogenic event in GC B-cell–derived lymphomagenesis.

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