AKT/GSK3β Signaling in Glioblastoma

Majewska, Ewelina; Szeliga, Monika

doi:10.1007/s11064-016-2044-4

Cited by 100 publications

(81 citation statements)

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“…AKT not only stabilizes cyclin D1 by phosphorylation and inactivation of GSK3β but also directly inhibits p21 and p27 [33,34]. Moreover, as a downstream effector, GSK3β can also regulate cyclin D1 [15,22,44], while GSK3β inhibition increases the level of p21 and downregulates CDK and p-RB, which can block cell cycle progression [32,33]. In this study, we demonstrated that peiminine significantly inhibits phosphorylation of AKT and GSK3β in GBM cell lines (Fig.…”

Section: Discussionmentioning

confidence: 52%

“…As is well known, the protein kinase B (AKT)-glycogen synthase kinase 3β (GSK3β) pathway controls many intracellular processes involved in cancer cell growth, proliferation, angiogenesis, metabolism and motility in GBM [14,15]. Many studies have shown that inhibiting the AKT pathway and its downstream effector, GSK3β, reduced the growth of GBM cells [16,17].…”

Section: Introductionmentioning

confidence: 99%

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Peiminine Inhibits Glioblastoma in Vitro and in Vivo Through Cell Cycle Arrest and Autophagic Flux Blocking

Zhao¹,

Shen²,

Zheng³

et al. 2018

Cell Physiol Biochem

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Background/Aims: Glioblastoma multiforme (GBM) is the most devastating and widespread primary central nervous system tumour in adults, with poor survival rate and high mortality rates. Existing treatments do not provide substantial benefits to patients; therefore, novel treatment strategies are required. Peiminine, a natural bioactive compound extracted from the traditional Chinese medicine Fritillaria thunbergii, has many pharmacological effects, especially anticancer activities. However, its anticancer effects on GBM and the underlying mechanism have not been demonstrated. This study was conducted to investigate the potential antitumour effects of peiminine in human GBM cells and to explore the related molecular signalling mechanisms in vitro and in vivo Methods: Cell viability and proliferation were detected with MTT and colony formation assays. Morphological changes associated with autophagy were assessed by transmission electron microscopy (TEM). The cell cycle rate was measured by flow cytometry. To detect changes in related genes and signalling pathways in vitro and in vivo, RNA-seq, Western blotting and immunohistochemical analyses were employed. Results: Peiminine significantly inhibited the proliferation and colony formation of GBM cells and resulted in changes in many tumour-related genes and transcriptional products. The potential anti-GBM role of peiminine might involve cell cycle arrest and autophagic flux blocking via changes in expression of the cyclin D1/CDK network, p62 and LC3. Changes in Changes in flow cytometry results and TEM findings were also observed. Molecular alterations included downregulation of the expression of not only phospho-Akt and phospho-GSK3β but also phospho-AMPK and phospho-ULK1. Furthermore, overexpression of AKT and inhibition of AKT reversed and augmented peiminine-induced cell cycle arrest in GBM cells, respectively. The cellular activation of AMPK reversed the changes in the levels of protein markers of autophagic flux. These results demonstrated that peiminine mediates cell cycle arrest by suppressing AktGSk3β signalling and blocks autophagic flux by depressing AMPK-ULK1 signalling in GBM cells. Finally, peiminine inhibited the growth of U251 gliomas in vivo. Conclusion: Peiminine inhibits glioblastoma in vitro and in vivo via arresting the cell cycle and blocking autophagic flux, suggesting new avenues for GBM therapy.

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Section: Discussionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Peiminine Inhibits Glioblastoma in Vitro and in Vivo Through Cell Cycle Arrest and Autophagic Flux Blocking

Zhao¹,

Shen²,

Zheng³

et al. 2018

Cell Physiol Biochem

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“…However, protein phosphatases also may influence GSK3β phosphorylation through the Akt pathway (Millward et al, 1999; Bononi et al, 2011). In the Akt pathway, stimulation of the phosphoinositide 3-kinase/Akt pathway leads to activation of Akt via phosphorylation of T308 and S473 residues, and then active Akt phosphorylates GSK3β/α at S9/21 (Gold et al, 2000; Varea et al, 2010; Majewska and Szeliga, 2016). Protein phosphatases (in particular protein phosphatase 2A) dephosphorylate Akt leading to Akt inactivation, and subsequently increased active GSK3β/α via the loss of Akt-mediated S9/21 phosphorylation (Millward et al, 1999; Bononi et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…S9/S21 phosphorylation leads to inactivation because the N-terminus of GSK3 competitively blocks substrate docking in the primed substrate pocket (Frame et al, 2001) acting as a dominant negative regulator of GSK3 activity, especially against substrates requiring priming. In situ , GSK3 is regulated, at least in part, by phosphorylation at S9 from Akt leading to reduced activity (Gold et al, 2000; Varea et al, 2010; Majewska and Szeliga, 2016) and protein phosphatases that dephosphorylate S9 leading to increased activity under several biological contexts (Sutherland et al, 1993; Leung-Hagesteijn et al, 2001; Morfini et al, 2004; Lee et al, 2005; Szatmari et al, 2005; Bertrand et al, 2012). However, the lack of reagents that specifically detect nonphospho-S9 (npS9) GSK3 has limited our ability to directly study dephosphorylation of this N-terminal serine.…”

Section: Introductionmentioning

confidence: 99%

Novel Non-phosphorylated Serine 9/21 GSK3β/α Antibodies: Expanding the Tools for Studying GSK3 Regulation

Grabinski

Kanaan

2016

Front. Mol. Neurosci.

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Glycogen synthase kinase 3 (GSK3) β and α are serine/threonine kinases involved in many biological processes. A primary mechanism of GSK3 activity regulation is phosphorylation of N-terminal serine (S) residues (S9 in GSK3β, S21 in GSK3α). Phosphorylation is inhibitory to GSK3 kinase activity because the phosphorylated N-terminus acts as a competitive inhibitor for primed substrates. Despite widespread interest in GSK3 across most fields of biology, the research community does not have reagents that specifically react with nonphosphoS9/21 GSK3β/α (the so-called “active” form). Here, we describe two novel monoclonal antibodies that specifically react with nonphosphoS9/21 GSK3β/α in multiple species (human, mouse, and rat). One of the antibodies is specific for nonphospho-S9 GSK3β (clone 12B2) and one for nonphospho-S9/21 GSK3β/α (clone 15C2). These reagents were validated for specificity and reactivity in several biochemical and immunochemical assays, and they show linear detection of nonphosphoS GSK3. Finally, these reagents provide significant advantages in studying GSK3β regulation. We used both antibodies to study the regulation of S9 phosphorylation by Akt and protein phosphatases. We used 12B2 (due to its specificity for GSK3β) and to demonstrate that protein phosphatase inhibition reduces nonphospho-S9 GSK3β levels and lowers kinase activity within cells. The ability to use the same reagent across biochemical, immunohistological and kinase activity assays provides a powerful approach for studying serine-dependent regulation of GSK3β/α.

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“…mTOR is a Ser/Thr kinase that belongs to the phosphoinositide kinase-related family of protein kinases (PIKKs). mTOR acts as an essential integrator of growth-factor-activated and nutrient-sensing pathways to control and coordinate various cellular functions, including survival, proliferation, differentiation, autophagy and metabolism (8)(9)(10)(11) This article is freely accessible online. *These authors contributed equally to this study.…”

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confidence: 99%

Combination of a STAT3 Inhibitor and an mTOR Inhibitor Against a Temozolomide-resistant Glioblastoma Cell Line

Miyata

Ashizawa

Iizuka

et al. 2017

CGP

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Abstract. Background: Temozolomide-resistant (TMZ-R) glioblastoma is very difficult to treat, and a novel approach toGlioblastoma (GB) is one of the most malignant and aggressive tumors and has a very poor prognosis, with a mean survival time of less than 2 years even with the recent development of temozolomide (TMZ)-based intensive treatment (1, 2). Once recurrence develops, there are few therapeutic approaches to control the growth of glioblastoma. Therefore, TMZ-resistant GB is very difficult to treat, and a novel approach to overcome resistance is needed.With regard to the mechanism of TMZ resistance, O 6 -methylguanine-DNA -methyltransferase (MGMT) removes methylation from the O 6 position of guanine and contributes to TMZ resistance induction (3). It is generally accepted that high MGMT expression through the methylation of the MGMT promoter is one of the mechanisms responsible for TMZ resistance. Alternatively, several novel biomarkers linked to MGMT expression and the methylation status such as the HOX signature and epidermal growth factor receptor (EGFR) expression (4), somatic mutation of mismatch repair gene mutS homolog (MSH)6 (5), prolyl 4-hydroxylase, beta polypeptide (P4HB), EGFR mutation (EGFRvIII) (6), CD74 and signal transducer and activator of transcription (STAT)3 signaling have been reported. Kohsaka et al. reported the association of STAT3 expression with MGMT expression level using small interfering (si)RNA-mediated STAT3 gene inhibition (7).Additionally, mammalian target of rapamycin (mTOR) signaling is activated in TMZ-resistant glioma cells as a result of EGFR, phosphoinositide 3 kinase (PI3K) and Akt signaling activation. mTOR is a Ser/Thr kinase that belongs to the phosphoinositide kinase-related family of protein kinases (PIKKs). mTOR acts as an essential integrator of growth-factor-activated and nutrient-sensing pathways to control and coordinate various cellular functions, including survival, proliferation, differentiation, autophagy and metabolism (8)(9)(10)(11) This article is freely accessible online. *These authors contributed equally to this study.Abbreviations: GB: Glioblastoma, TMZ: temozolomide, MGMT: O 6 -methylguanine-O 6 -methylguanine-DNAmethyltransferase, STAT: signal transducer and activator of transcription, mTOR: mammalian target of rapamycin, shRNA: small hairpin RNA.

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AKT/GSK3β Signaling in Glioblastoma

Cited by 100 publications

References 61 publications

Peiminine Inhibits Glioblastoma in Vitro and in Vivo Through Cell Cycle Arrest and Autophagic Flux Blocking

Peiminine Inhibits Glioblastoma in Vitro and in Vivo Through Cell Cycle Arrest and Autophagic Flux Blocking

Novel Non-phosphorylated Serine 9/21 GSK3β/α Antibodies: Expanding the Tools for Studying GSK3 Regulation

Combination of a STAT3 Inhibitor and an mTOR Inhibitor Against a Temozolomide-resistant Glioblastoma Cell Line

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