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Oncogenic PIK3CA corrupts growth factor signalling specificity

ABSTRACT: Pathological activation of the PI3K/AKT pathway is among the most frequent defects in human cancer and is also the cause of rare overgrowth disorders. Yet, unlike the related oncogenic RAS/MAPK pathway, there is currently no systematic understanding of the quantitative flow of information within PI3K/AKT signalling and how it is perturbed by disease-causing mutations. Here, we develop scalable, single-cell approaches for systematic studies of signal processing within the PI3K pathway, enabling precise calculations of its information transfer for different growth factors. Using genetically engineered human cell models with allele dose-dependent expression of PIK3CAH1047R, we show that this oncogene is not a simple, constitutive pathway activator but a context-dependent modulator of extracellular signal transfer. PIK3CAH1047R reduces information transfer downstream of IGF1 while selectively enhancing EGF-induced signalling and transcriptional responses. This leads to a gross reduction in signalling specificity, akin to “blurred” signal perception. The associated increase in signalling heterogeneity increases phenotypic diversity in a cervical cancer cell model and in human induced pluripotent stem cells. Collectively, these findings and the accompanying methodological advances lay the foundations for a systematic mapping of the quantitative mechanisms of PI3K/AKT-dependent signal processing and phenotypic control in health and disease.

ORGANISM(S): Homo sapiens

PROVIDER: GSE251956 | GEO | 2023/12/27

REPOSITORIES: GEO

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Project description:Mosca2012 - Central Carbon Metabolism Regulated by AKT The role of the PI3K/Akt/PKB signalling pathway in oncogenesis has been extensively investigated and altered expression or mutations of many components of this pathway have been implicated in human cancers. Indeed, expression of constitutively active forms of Akt/PKB can prevent cell death upon growth factor withdrawal. PI3K/Akt/mTOR-mediated survival relies on a profound metabolic adaptation, including aerobic glycolysis. Here, the link between the PI3K/Akt/mTOR pathway, glycolysis, lactic acid production and nucleotide biosynthesis has been modelled, considering two states - high and low PI3K/Akt/mTOR activity. The high PI3K/Akt/mTOR activity represents cancer cell line where PI3K/Akt/mTOR promotes a high rate of glucose metabolism (condition H) and the low PI3K/Akt/mTOR activity is characterised by a lower glycolytic rate due to a reduced PI3K/Akt/mTOR signal (condition L). This model corresponds to the high PI3K/Akt/mTOR signal (condition H). This model is described in the article: Computational Modelling of the Metabolic States Regulated by the Kinase Akt. Mosca E, Alfieri R, Maj C, Bevilacqua A, Canti G, Milanesi L. Frontiers in Systems Biology. 2012 Oct 13 Abstract: Signal transduction pathways and gene regulation determine a major reorganization of metabolic activities in order to support cell proliferation. Protein Kinase B (PKB), also known as Akt, participates in the PI3K/Akt/mTOR pathway, a master regulator of aerobic glycolysis and cellular biosynthesis, two activities shown by both normal and cancer proliferating cells. Not surprisingly considering its relevance for cellular metabolism, Akt/PKB is often found hyperactive in cancer cells. In the last decade, many efforts have been made to improve the understanding of the control of glucose metabolism and the identification of a therapeutic window between proliferating cancer cells and proliferating normal cells. In this context, we have modelled the link between the PI3K/Akt/mTOR pathway, glycolysis, lactic acid production and nucleotide biosynthesis. We used a computational model in order to compare two metabolic states generated by the specific variation of the metabolic fluxes regulated by the activity of the PI3K/Akt/mTOR pathway. One of the two states represented the metabolism of a growing cancer cell characterised by aerobic glycolysis and cellular biosynthesis, while the other state represented the same metabolic network with a reduced glycolytic rate and a higher mitochondrial pyruvate metabolism, as reported in literature in relation to the activity of the PI3K/Akt/mTOR. Some steps that link glycolysis and pentose phosphate pathway revealed their importance for controlling the dynamics of cancer glucose metabolism. This model is hosted on BioModels Database and identified by: MODEL1210150000 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Hyperactivation of the PI3K/AKT pathway is observed in most NSCLCs, promoting proliferation, migration and resistance to therapy. AKT can be activated through several mechanisms that include loss of the negative regulator PTEN, activating mutations of the catalytic subunit of the positive regulator phosphatydil-inositol-3â phosphate kinase (PIK3CA) and/or mutations of AKT1 itself. However, whereas the effects of AKT activation on mRNAs and proteins in the cell are fairly clear, the role of miRNAs as downstream targets of activated PI3K/AKT signalling is still poorly defined so far. To identify miRNAs that are targets of constitutive signalling of PI3K/AKT in lung cancer cells, we performed miRNA profiling of human lung epithelial cells expressing active mutant AKT1 (E17K), active mutant PI3KCA (E545K) or that are silenced for PTEN. We identified 28 differentially expressed miRNAs (8 up-regulated, 20 down-regulated) that were common to BEAS-AKT1-E17K, BEAS-PIK3CA-E545K and BEAS-shPTEN cells. Among the 8 up-regulated miRNAs that were common to all the alterations, the miRNA most consistently up-regulated by activation of the PI3K/AKT pathway in BEAS-2B cells was miR-196a. The results reported here demonstrate that miR-196a acts as oncogene downstream the PI3K/AKT pathway, mediating the proliferative, pro-migratory and tumorigenic activity of this pathway in NSCLC cells by targeting FoxO1 and p27 expression. By adoptive expression of miR-196a in BEAS-2B cells, we demonstrated that miR-196a stimulates anchorage-dependent and -independent proliferation, migration and tumorigenicity in BEAS-2B cells. On the other hand, by use of antimir-196a in NCI-H460 cells to silence the endogenous expression of miR-196a, we demonstrate that miR-196a plays a pivotal role in mediating the stimulation of proliferation, migration and tumorigenicity induced by aberrant activation of PI3K/AKT signalling. Accordingly, we found that miR-196a was significantly overexpressed in human NSCLC-derived cell lines (n=6) and primary lung cancer samples (n=28). Finally, based on predicted binding sites for miR-196a by microRNA analysis software, we found that miR-196a affects protein levels of FoxO1 and p27 in NSCLC cells.

Project description:Padala2017- ERK, PI3K/Akt and Wnt signalling network (PI3K mutated) Crosstalk model of the ERK, Wnt and Akt signalling pathways with mutated PI3K. This model is described in the article: Cancerous perturbations within the ERK, PI3K/Akt, and Wnt/?-catenin signaling network constitutively activate inter-pathway positive feedback loops. Padala RR, Karnawat R, Viswanathan SB, Thakkar AV, Das AB. Mol Biosyst 2017 May; 13(5): 830-840 Abstract: Perturbations in molecular signaling pathways are a result of genetic or epigenetic alterations, which may lead to malignant transformation of cells. Despite cellular robustness, specific genetic or epigenetic changes of any gene can trigger a cascade of failures, which result in the malfunctioning of cell signaling pathways and lead to cancer phenotypes. The extent of cellular robustness has a link with the architecture of the network such as feedback and feedforward loops. Perturbation in components within feedback loops causes a transition from a regulated to a persistently activated state and results in uncontrolled cell growth. This work represents the mathematical and quantitative modeling of ERK, PI3K/Akt, and Wnt/?-catenin signaling crosstalk to show the dynamics of signaling responses during genetic and epigenetic changes in cancer. ERK, PI3K/Akt, and Wnt/?-catenin signaling crosstalk networks include both intra and inter-pathway feedback loops which function in a controlled fashion in a healthy cell. Our results show that cancerous perturbations of components such as EGFR, Ras, B-Raf, PTEN, and components of the destruction complex cause extreme fragility in the network and constitutively activate inter-pathway positive feedback loops. We observed that the aberrant signaling response due to the failure of specific network components is transmitted throughout the network via crosstalk, generating an additive effect on cancer growth and proliferation. This model is hosted on BioModels Database and identified by: BIOMD0000000652. To cite BioModels Database, please use: Chelliah V et al. BioModels: ten-year anniversary. Nucl. Acids Res. 2015, 43(Database issue):D542-8. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

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Oncogenic PIK3CA corrupts growth factor signalling specificity

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