Project description:Akt is a robust oncogene that plays key roles in the development and progression of many cancers, including glioma. We evaluated the differential propensities of the Akt isoforms toward progression in the well-characterized RCAs/Ntv-a mouse model of PDGFB-driven low grade glioma. A constitutively active myristoylated form of Akt1 did not induce high-grade glioma (HGG). In stark contrast, Akt2 and Akt3 showed strong progression potential with 78% and 97% of tumors diagnosed as HGG, respectively. We further revealed that significant variations in polarity and hydropathy values among the Akt isoforms in both the pleckstrin homology domain (P domain) and regulatory domain (R domain) were critical in mediating glioma progression. Gene expression profiles from representative Akt-derived tumors indicated dominant and distinct roles for Akt3, consisting primarily of DNA repair pathways. TCGA data from human GBM closely reflected the DNA repair function, as Akt3 was significantly correlated with a 76 gene signature DNA repair panel. Consistently, compared to Akt1 and Akt2 overexpression models, Akt3-expressing human GBM cells had enhanced activation of DNA repair proteins, leading to increased DNA repair and subsequent resistance to radiation and temozolomide. Given the wide range of Akt3-amplified cancers, Akt3 may represent a key resistance factor. 5 different experimental conditions were compared (including GFP, PDGFB, PDGFB in conjunciton with Akt1, Akt2, or Akt3) with 3 mice per treatment
Project description:Akt is a robust oncogene that plays key roles in the development and progression of many cancers, including glioma. We evaluated the differential propensities of the Akt isoforms toward progression in the well-characterized RCAs/Ntv-a mouse model of PDGFB-driven low grade glioma. A constitutively active myristoylated form of Akt1 did not induce high-grade glioma (HGG). In stark contrast, Akt2 and Akt3 showed strong progression potential with 78% and 97% of tumors diagnosed as HGG, respectively. We further revealed that significant variations in polarity and hydropathy values among the Akt isoforms in both the pleckstrin homology domain (P domain) and regulatory domain (R domain) were critical in mediating glioma progression. Gene expression profiles from representative Akt-derived tumors indicated dominant and distinct roles for Akt3, consisting primarily of DNA repair pathways. TCGA data from human GBM closely reflected the DNA repair function, as Akt3 was significantly correlated with a 76 gene signature DNA repair panel. Consistently, compared to Akt1 and Akt2 overexpression models, Akt3-expressing human GBM cells had enhanced activation of DNA repair proteins, leading to increased DNA repair and subsequent resistance to radiation and temozolomide. Given the wide range of Akt3-amplified cancers, Akt3 may represent a key resistance factor.
Project description:The receptor tyrosine kinase AXL promotes tumor progression, metastasis and therapy resistance through the induction of epithelial-mesenchymal transition (EMT). Here, we report that activation of AXL results in TANK-binding kinase 1 (TBK1) phosphorylation, subsequent TBK1-dependent phosphorylation of AKT3 (pAKT3) and nuclear accumulation of pAKT3 and the EMT transcription factor (EMT-TF) Snail. Mechanistically, we show that (i) TBK1 directly binds and phosphorylates AKT3, in an mTORC1 dependent manner. Once activated, AKT3 interacts with Snail and promotes the accumulation of nuclear Snail to drive EMT. Congruently, in human pancreatic ductaladenocarcinoma tissue, nuclear AKT3 co-localizes with Snail and correlates with worse clinical outcome. AKT3 knockout in tumor cells significantly reduced metastatic spread in mice suggesting that selective AKT3 inhibition represents a novel therapeutic avenue for targeting EMT in aggressive cancers.
Project description:Insulin-like growth factor-binding protein 2 (IGFBP2) is increasingly recognized as a glioma oncogene, emerging as a target for therapeutic intervention. In this study, we used an integrative approach to characterizing the IGFBP2 network, combining transcriptional profiling of human glioma with validation in glial cells and the replication competent ASLV long terminal repeat with a splice acceptor/tv-a glioma mouse system. We demonstrated that IGFBP2 expression is closely linked to genes in the integrin and integrin-linked kinase (ILK) pathways and that these genes are associated with prognosis. We further showed that IGFBP2 activates integrin ?1 and down- stream invasion pathways, requires ILK to induce cell motility, and activates NF-?B. Most significantly, the IGFBP2/integrin/ILK/NF-?B network functions as a physiologically active signaling pathway in vivo by driving glioma progression; interfering with any point in the pathway markedly inhibits progression. The results of this study reveal a signaling pathway that is both targetable and highly relevant to improving the survival of glioma patients. We performed cDNA microarray analysis to compare two stably expressing cell lines originating from SNB19; two clones expressing a mutant form of IGFBP2 that cannot bind integrin (RGD ? RGE point mutation; referred to as RGE mutant); and two clones expressing wild-type IGFBP2. SNB19 clones transfected with empty vector were placed in the reference channel in each hybridization.
Project description:Insulin-like growth factor-binding protein 2 (IGFBP2) is increasingly recognized as a glioma oncogene, emerging as a target for therapeutic intervention. In this study, we used an integrative approach to characterizing the IGFBP2 network, combining transcriptional profiling of human glioma with validation in glial cells and the replication competent ASLV long terminal repeat with a splice acceptor/tv-a glioma mouse system. We demonstrated that IGFBP2 expression is closely linked to genes in the integrin and integrin-linked kinase (ILK) pathways and that these genes are associated with prognosis. We further showed that IGFBP2 activates integrin β1 and down- stream invasion pathways, requires ILK to induce cell motility, and activates NF-κB. Most significantly, the IGFBP2/integrin/ILK/NF-κB network functions as a physiologically active signaling pathway in vivo by driving glioma progression; interfering with any point in the pathway markedly inhibits progression. The results of this study reveal a signaling pathway that is both targetable and highly relevant to improving the survival of glioma patients.
Project description:DNA interstrand crosslinks (ICLs) block replication fork progression by inhibiting DNA strand separation. Repair of ICLs requires sequential incisions, translesion DNA synthesis, and homologous recombination, but the full set of factors involved in these transactions remains unknown. Here we established CHROmatin MASS spectrometry (CHROMASS) to study protein recruitment dynamics during perturbed DNA replication in Xenopus egg extracts. Using CHROMASS, we systematically monitored protein assembly and disassembly at ICL-containing chromatin. Among numerous prospective new DNA repair factors we identified SLF1 and SLF2, which form a complex with RAD18 and together define a new pathway that suppresses genome instability by recruiting the SMC5/6 cohesion complex to DNA lesions. Our study provides the first global analysis of an entire DNA repair pathway and reveals the mechanism of SMC5/6 relocalization to damaged DNA in vertebrate cells.
Project description:Isocitrate dehydrogenase 1 (IDH1) mutations are key drivers of glioma biology, influenc-ing tumor aggressiveness and treatment response. To elucidate their molecular impact, we performed proteome analysis on patient-derived (PD) and U87MG glioma cell models with either mutant or wildtype IDH1. We quantified over 6,000 protein groups per model, identifying 1,594 differentially expressed proteins in PD-AS (IDH1MUT) vs. PD-GB (IDH1WT) and 904 in U87MUT vs. U87WT. Both IDH1MUT models exhibited enhanced MHC antigen presentation and interferon signaling, indicative of an altered immune microen-vironment. However, metabolic alterations were model-dependent: PD-AS cells shifted toward glycolysis and purine salvage, while U87MUT cells retained oxidative phosphory-lation, potentially due to D2-hydroxyglutarate (2OHG)-mediated HIF1A stabilization. We also observed a predominance of downregulated DNA repair proteins in IDH1MUT mod-els, particularly those involved in homologous recombination. In contrast, RB1 and AS-MTL were strongly upregulated in both IDH1MUT models, implicating them in DNA repair and cellular stress responses. We also found distinct expression patterns of proteins reg-ulating histone methylation in IDH1MUT cells, favoring increased methylation of H3K4, H3K9, and H3K36. A key driver of this may be the upregulation of SETD2 in PD-AS, an H3K4 and H3K36 trimethyltransferase linked to recruitment of HIF1A as well as DNA mismatch repair proteins. This study uncovers candidate biomarkers and pathways rele-vant to glioma progression and therapeutic targeting but also underscores the complexity of predicting glioma pathogenesis and treatment responses based on IDH1 mutation sta-tus. While proteome profiling provides valuable insights, a comprehensive understand-ing of IDH1MUT gliomas will likely require integrative multi-omics approaches, including DNA/RNA methylation profiling, histone and protein post-translational modification analyses, and targeted DNA damage and repair assays.
Project description:The Fanconi Anemia (FA) pathway repairs DNA damage caused by endogenous and chemotherapy-induced DNA crosslinks. Genetic inactivation of this pathway impairs development, prevents blood production and promotes cancer. The key molecular step in the FA pathway is the monoubiquitination of a heterodimer of FANCI-FANCD2 by the FA core complex - a megadalton multiprotein E3 ubiquitin ligase. Monoubiquitinated FANCI-FANCD2 then activates a pathway to remove the DNA crosslink. Lack of molecular insight into the FA core complex limits a detailed explanation of how this vital DNA repair pathway functions. Here we reconstituted an active, recombinant FA core complex, and used electron cryo-microscopy (cryo-EM) and mass spectrometry to determine its overall structure. The FA core complex is comprised of a central symmetric dimer of the FANCB and FAAP100 subunits, flanked by two copies of the RING finger protein, FANCL. This acts as a scaffold to assemble the remaining five subunits, resulting in an extended asymmetric structure. The two FANCL subunits are positioned at opposite ends of the complex in an unusual asymmetric arrangement, distinct from other E3 ligases. We propose that each of the two FANCL subunits play unique roles within the complex – one is a structural component while the other monoubiquitinates FANCD2. The cryo-EM structure of the FA core complex, supported by crosslinking mass spectrometry and native mass spectrometry, therefore provides a foundation for a detailed understanding of this fundamental DNA repair pathway.
Project description:Glioma is the most common and aggressive primary malignant brain tumor. N6-methyladenosine (m6A) modification widely exists in eukaryotic cells and plays an important role in the occurrence and development of human tumors. Here, we show that the m6A reader HNRNPC was overexpression and related to poor prognosis in glioma patients. HNRNPC plays crucial role in glioma cell proliferation, invasion and tumorigenesis. HNRNPC augments m6A-dependent mRNA stability of IRAK1, which impacted poor survival for glioma patients, further activated the downstream MAPK pathway. HNRNPC promotes glioma cells progression largely through the upregulation of IRAK1. Together, our findings demonstrate the novel HNRNPC-IRAK1-MAPK axis critical for glioma tumorigenesis and extend the reason for the upregulation of IRAK1.