PKM2 Interacts With the Cdk1-CyclinB Complex to Facilitate Cell Cycle Progression in Gliomas

PKM2 is a phosphotyrosine-binding glycolytic enzyme upregulated in many cancers, including glioma, and contributes to tumor growth by regulating cell cycle progression. We noted, however, that in multiple glioma cell lines, PKM2 knock-down resulted in an accumulation of cells in G2-M phase. Moreover, PKM2 knock-down decreased Cdk1 activity while introducing a constitutively active Cdk1 reversed the effects of PKM2 knock-down on cell cycle progression. The means by which PKM2 increases Cdk1 activity have not been described. Transient interaction of T14/Y15-phosphorylated Cdk1 with cyclin B allows Cdk7-mediated pT161 Cdk1 phosphorylation followed by cdc25C-mediated removal of pT14/Y15 and activation of Cdk1 in cycling cells. In the present course of investigation, PKM2 modulation did not influence Cdk7 activity, but phosphotyrosine binding forms of PKM2 co-immunoprecipitated with pY15-containing Cdk1-cyclinB and enhanced formation of active pT161 Cdk1-cyclin B complexes. Moreover, exogenous expression of phosphotyrosine binding forms of PKM2 reversed the effects of PKM2 knock-down on G2-M arrest. We here show that PKM2 binds and stabilize otherwise transient pY15-containing Cdk1-cyclinB complexes that in turn facilitate Cdk1-cyclin B activation and entry of cells into mitosis. These results, therefore, establish metabolic enzyme PKM2 as a direct interactor and activator of Cdk1-cyclin B complex and thereby directly controls mitotic progression and the growth of brain tumor cells.publishedVersio

Phosphoglycerate mutase 1 (PGAM1) overexpression promotes radio- and chemoresistance in gliomas by activating the DNA damage response

The glycolytic enzyme PGAM1 is overexpressed in gliomas where it efficiently facilitates the repair of DNA damage. Mechanistically, PGAM1 prevents inactivation of the ataxia-telangiectasia mutated (ATM) signaling pathway by sequestering the wild-type p53-induced phosphatase 1 (WIP1) in the cytoplasm. Genetic inhibition of PGAM1 expression subsequently sensitizes glioma cells against irradiation and chemotherapy-induced DNA damage

Phosphoglycerate Mutase 1 Activates DNA Damage Repair via Regulation of WIP1 Activity

The metabolic enzyme phosphoglycerate mutase 1 (PGAM1) is overexpressed in several types of cancer, suggesting an additional function beyond its established role in the glycolytic pathway. We here report that PGAM1 is overexpressed in gliomas where it increases the efficiency of the DNA damage response (DDR) pathway by cytoplasmic binding of WIP1 phosphatase, thereby preventing WIP1 nuclear translocation and subsequent dephosphorylation of the ATM signaling pathway. Silencing of PGAM1 expression in glioma cells consequently decreases formation of γ-H2AX foci, increases apoptosis, and decreases clonogenicity following irradiation (IR) and temozolomide (TMZ) treatment. Furthermore, mice intracranially implanted with PGAM1-knockdown cells have significantly improved survival after treatment with IR and TMZ. These effects are counteracted by exogenous expression of two kinase-dead PGAM1 mutants, H186R and Y92F, indicating an important non-enzymatic function of PGAM1. Our findings identify PGAM1 as a potential therapeutic target in gliomas

Rapid Conversion of Mutant IDH1 from Driver to Passenger in a Model of Human Gliomagenesis.

Missense mutations in the active site of isocitrate dehydrogenase 1 (IDH1) biologically and diagnostically distinguish low-grade gliomas and secondary glioblastomas from primary glioblastomas. IDH1 mutations lead to the formation of the oncometabolite 2-hydroxyglutarate (2-HG) from the reduction of α-ketoglutarate (α-KG), which in turn facilitates tumorigenesis by modifying DNA and histone methylation as well blocking differentiation processes. Although mutant IDH1 expression is thought to drive the gliomagenesis process, the extent to which it remains a viable therapeutic target remains unknown. To address this question, we exposed immortalized (p53/pRb deficient), untransformed human astrocytes to the mutant IDH1 inhibitor AGI-5198 prior to, concomitant with, or at intervals after, introduction of transforming mutant IDH1, then measured effects on 2-HG levels, histone methylation (H3K4me3, H3K9me2, H3K9me3, or H3K27me3), and growth in soft agar. Addition of AGI-5198 prior to, or concomitant with, introduction of mutant IDH1 blocked all mutant IDH1-driven changes, including cellular transformation. Addition at time intervals as short as 4 days following introduction of mutant IDH1 also suppressed 2-HG levels, but had minimal effects on histone methylation, and lost the ability to suppress clonogenicity in a time-dependent manner. Furthermore, in two different models of mutant IDH1-driven gliomagenesis, AGI-5198 exposures that abolished production of 2-HG also failed to decrease histone methylation, adherent cell growth, or anchorage-independent growth in soft agar over a prolonged period. These studies show although mutant IDH1 expression drives gliomagenesis, mutant IDH1 itself rapidly converts from driver to passenger.ImplicationsAgents that target mutant IDH may be effective for a narrow time and may require further optimization or additional therapeutics in glioma. Mol Cancer Res; 14(10); 976-83. ©2016 AACR

Rapid Conversion of Mutant IDH1 from Driver to Passenger in a Model of Human Gliomagenesis

Missense mutations in the active site of isocitrate dehydrogenase 1 (IDH1) biologically and diagnostically distinguish low-grade gliomas and secondary glioblastomas from primary glioblastomas. IDH1 mutations lead to the formation of the oncometabolite 2-hydroxyglutarate (2-HG) from the reduction of α-ketoglutarate (α-KG), which in turn facilitates tumorigenesis by modifying DNA and histone methylation as well blocking differentiation processes. While mutant IDH1 expression is thought to drive the gliomagenesis process, the extent to which it remains a viable therapeutic target remains unknown. To address this question we exposed immortalized (p53/pRb-deficient), untransformed human astrocytes to the mutant IDH1 inhibitor AGI-5198 prior to, concomitant with, or at intervals after, introduction of transforming mutant IDH1, then measured effects on 2-HG levels, histone methylation (H3K4me3, H3K9me2, H3K9me3 or H3K27me3) and growth in soft-agar. Addition of AGI-5198 prior to, or concomitant with, introduction of mutant IDH1 blocked all mutant IDH1-driven changes including cellular transformation. Addition at time intervals as short as 4 days following introduction of mutant IDH1 also suppressed 2-HG levels, but had minimal effects on histone methylation, and lost the ability to suppress clonogenicity in a time-dependent manner. Furthermore, in two different models of mutant IDH1-driven gliomagenesis, AGI-5198 exposures that abolished production of 2-HG also failed to decrease histone methylation, adherent cell growth, or anchorage-independent growth in soft-agar over a prolonged period. These studies show although mutant IDH1 expression drives gliomagenesis, mutant IDH1 itself rapidly converts from driver to passenger. IMPLICATIONS: Agents that target mutant IDH may be effective for a narrow time and may require further optimization or additional therapeutics in glioma

Glioblastom hos voksne

Glioblastom er den vanligste formen for primær hjernekreft hos voksne, og sykdommen har en alvorlig prognose. Selv om det er gjort store fremskritt i molekylær karakteristikk, har det ikke vært større gjennombrudd i behandlingen på mange år. Vi presenterer her en klinisk oversikt over dagens diagnostikk og behandling samt hvilke utfordringer og muligheter som ligger i å utvikle bedre og mer persontilpasset behandling. Hvert år rammes over 200 mennesker i Norge av glioblastom (1). Median overlevelse for alle pasienter i Norge er kun 11 måneder (2). Med full onkologisk behandling er median overlevelse 15 måneder, og femårsoverlevelse er 6,8 % (3, 4). Glioblastomer antas å oppstå fra nevrogliale stamceller eller progenitorceller, og er preget av betydelig molekylær heterogenitet. De aller fleste glioblastomer er sporadisk forekommende og ses hyppigere ved økende alder og hos menn (4). Kun en liten andel kan tilskrives tidligere eksponering for ioniserende stråling eller arvelige faktorer (4).. Formålet med denne artikkelen er å gi norske klinikere en oppdatert oversikt over diagnostikk og behandling samt å belyse faktorer som har vesentlig betydning for behandling. Artikkelen er basert på gjennomgang av relevant norsk og internasjonal litteratur samt forfatternes egne erfaringer med pasientgruppen. Flere av forfatterne er medlemmer av Norsk hjernesvulstkonsortium (NBTC, Norwegian Brain Tumor Consortium)

Investigating survival, quality of life and cognition in PROton versus photon therapy for IDH-mutated diffuse grade 2 and 3 GLIOmas (PRO-GLIO): a randomised controlled trial in Norway and Sweden

Introduction The use of proton therapy increases globally despite a lack of randomised controlled trials demonstrating its efficacy and safety. Proton therapy enables sparing of non-neoplastic tissue from radiation. This is principally beneficial and holds promise of reduced long-term side effects. However, the sparing of seemingly non-cancerous tissue is not necessarily positive for isocitrate dehydrogenase (IDH)-mutated diffuse gliomas grade 2–3, which have a diffuse growth pattern. With their relatively good prognosis, yet incurable nature, therapy needs to be delicately balanced to achieve a maximal survival benefit combined with an optimised quality of life.Methods and analysis PRO-GLIO (PROton versus photon therapy in IDH-mutated diffuse grade 2 and 3 GLIOmas) is an open-label, multicentre, randomised phase III non-inferiority study. 224 patients aged 18–65 years with IDH-mutated diffuse gliomas grade 2–3 from Norway and Sweden will be randomised 1:1 to radiotherapy delivered with protons (experimental arm) or photons (standard arm). First intervention-free survival at 2 years is the primary endpoint. Key secondary endpoints are fatigue and cognitive impairment, both at 2 years. Additional secondary outcomes include several survival measures, health-related quality of life parameters and health economy endpoints.Ethics and dissemination To implement proton therapy as part of standard of care for patients with IDH-mutated diffuse gliomas grade 2–3, it should be deemed safe. With its randomised controlled design testing proton versus photon therapy, PRO-GLIO will provide important information for this patient population concerning safety, cognition, fatigue and other quality of life parameters. As proton therapy is considerably more costly than its photon counterpart, cost-effectiveness will also be evaluated. PRO-GLIO is approved by ethical committees in Norway (Regional Committee for Medical & Health Research Ethics) and Sweden (The Swedish Ethical Review Authority) and patient inclusion has commenced. Trial results will be published in international peer-reviewed journals, relevant conferences, national and international meetings and expert forums.Trial registration number ClinicalTrials.gov Registry (NCT05190172)