IDH1 R132H Mutation Enhances Cell Migration by Activating AKT-mTOR Signaling Pathway, but Sensitizes Cells to 5-FU Treatment as NADPH and GSH Are Reduced

Successful sirolimus treatment of spindle cell haemangiomas in a paediatric patient with Maffucci syndrome

A case of Maffucci syndrome in a paediatric patient was treated satisfactorily with sirolimus, creating an opportunity for complete surgical excision of spindle cell haemangiomas.

The correlation analysis of TERT promoter mutations with IDH1/2 mutations and 1p/19q detected in human gliomas

BACKGROUND

To investigate the correlations between mutations in the telomerase reverse transcriptase (TERT) promoter and isocitrate dehydrogenase (IDH) 1 and 2 mutations or 1p/19q deletion in human gliomas.

METHODS

TERT promoter gene and IDH gene mutations in 110 glioma specimens were evaluated using first generation Sanger sequencing. The 1p/19q status was determined with fluorescence in situ hybridization. The relationship between TERT promoter mutations and IDH gene mutations as well as 1p/19q deletion was analyzed using the χ2 test and Spearman rank correlation test.

RESULTS

The TERT promoter mutation rate in 110 glioma specimens was 39.09% (43/110), with a rate of 32.56% (14/43) for C228T mutation and 67.44% (29/43) for C250T mutation. The IDH gene mutation rate in all specimens was 31.82% (35/110), with a rate of 52.78% (19/36) in low-grade gliomas and 21.62% (16/74) in high grade gliomas. The 1p/19q deletion rate was 28.18% (31/110) in all specimens. Correlation analysis revealed that TERT promoter mutation was positively correlated with 1p/19q deletion (relative precision (rp) = 0.244, P = .015). In lower-grade glioma with IDH mutation, TERT promoter mutation was positively correlated with 1p/19q deletion (rp = 0.856, P = .000). The prognosis for gliomas with IDH mutation/TERT mutation/1p/19qdeletion was good. Mutation of the TERT promoter was negatively correlated with IDH gene mutation (rp = -0.290, P = .004), except in 10 cases of oligodendroglioma and 1 case of anaplastic oligodendroglioma.

CONCLUSION

There may be a complex inter-regulatory relationship between the mutations of the TERT promoter and IDH gene as well as 1p/19q abnormalities in human gliomas.

Different Effects of RNAi-Mediated Downregulation or Chemical Inhibition of NAMPT in an Isogenic IDH Mutant and Wild-Type Glioma Cell Model

The IDH1^R132H mutation in glioma results in the neoenzymatic function of IDH1, leading to the production of the oncometabolite 2-hydroxyglutarate (2-HG), alterations in energy metabolism and changes in the cellular redox household. Although shifts in the redox ratio NADPH/NADP⁺ were described, the consequences for the NAD⁺ synthesis pathways and potential therapeutic interventions were largely unexplored. Here, we describe the effects of heterozygous IDH1^R132H on the redox system in a CRISPR/Cas edited glioblastoma model and compare them with IDH1 wild-type (IDH1^wt) cells. Besides an increase in 2-HG and decrease in NADPH, we observed an increase in NAD⁺ in IDH1^R132H glioblastoma cells. RT-qPCR analysis revealed the upregulation of the expression of the NAD⁺ synthesis enzyme nicotinamide phosphoribosyltransferase (NAMPT). Knockdown of NAMPT resulted in significantly reduced viability in IDH1^R132H glioblastoma cells. Given this dependence of IDH1^R132H cells on NAMPT expression, we explored the effects of the NAMPT inhibitors FK866, GMX1778 and GNE-617. Surprisingly, these agents were equally cytotoxic to IDH1^R132H and IDH1^wt cells. Altogether, our results indicate that targeting the NAD⁺ synthesis pathway is a promising therapeutic strategy in IDH mutant gliomas; however, the agent should be carefully considered since three small-molecule inhibitors of NAMPT tested in this study were not suitable for this purpose.

Molecular Pathogenesis of Glioblastoma in Adults and Future Perspectives: A Systematic Review

Glioblastoma (GBM) is the most common and malignant tumour of the central nervous system. Recent appreciation of the heterogeneity amongst these tumours not only changed the WHO classification approach, but also created the need for developing novel and personalised therapies. This systematic review aims to highlight recent advancements in understanding the molecular pathogenesis of the GBM and discuss related novel treatment targets. A systematic search of the literature in the PubMed library was performed following the PRISMA guidelines for molecular pathogenesis and therapeutic advances. Original and meta-analyses studies from the last ten years were reviewed using pre-determined search terms. The results included articles relevant to GBM development focusing on the aberrancy in cell signaling pathways and intracellular events. Theragnostic targets and vaccination to treat GBM were also explored. The molecular pathophysiology of GBM is complex. Our systematic review suggests targeting therapy at the stemness, p53 mediated pathways and immune modulation. Exciting novel immune therapy involving dendritic cell vaccines, B-cell vaccines and viral vectors may be the future of treating GBM.

A Genome-Wide Profiling of Glioma Patients with an IDH1 Mutation Using the Catalogue of Somatic Mutations in Cancer Database

Simple Summary

Glioma patients that present a somatic mutation in the isocitrate dehydrogenase 1 (IDH1) gene have a significantly better prognosis and overall survival than patients with the wild-type genotype. An IDH1 mutation is hypothesized to occur early during cellular transformation and leads to further genetic instability. A genome-wide profiling of glioma patients in the Catalogue of Somatic Mutations in Cancer (COSMIC) database was performed to classify the genetic differences in IDH1-mutant versus IDH1-wildtype patients. This classification will aid in a better understanding of how this specific mutation influences the genetic make-up of glioma and the resulting prognosis. Key differences in co-mutation and gene expression levels were identified that correlate with an improved prognosis.

Abstract

Gliomas are differentiated into two major disease subtypes, astrocytoma or oligodendroglioma, which are then characterized as either IDH (isocitrate dehydrogenase)-wild type or IDH-mutant due to the dramatic differences in prognosis and overall survival. Here, we investigated the genetic background of IDH1-mutant gliomas using the Catalogue of Somatic Mutations in Cancer (COSMIC) database. In astrocytoma patients, we found that IDH1 is often co-mutated with TP53, ATRX, AMBRA1, PREX1, and NOTCH1, but not CHEK2, EGFR, PTEN, or the zinc finger transcription factor ZNF429. The majority of the mutations observed in these genes were further confirmed to be either drivers or pathogenic by the Cancer-Related Analysis of Variants Toolkit (CRAVAT). Gene expression analysis showed down-regulation of DRG2 and MSN expression, both of which promote cell proliferation and invasion. There was also significant over-expression of genes such as NDRG3 and KCNB1 in IDH1-mutant astrocytoma patients. We conclude that IDH1-mutant glioma is characterized by significant genetic changes that could contribute to a better prognosis in glioma patients.

Specific patterns of H3K79 methylation influence genetic interaction of oncogenes in AML

Understanding mechanisms of cooperation between oncogenes is critical for the development of novel therapies and rational combinations. Acute myeloid leukemia (AML) cells with KMT2A-fusions and KMT2A partial tandem duplications (KMT2APTD) are known to depend on the histone methyltransferase DOT1L, which methylates histone 3 lysine 79 (H3K79). About 30% of KMT2APTD AMLs carry mutations in IDH1/2 (mIDH1/2). Previous studies showed that 2-hydroxyglutarate produced by mIDH1/2 increases H3K79 methylation, and mIDH1/2 patient samples are sensitive to DOT1L inhibition. Together, these findings suggested that stabilization or increases in H3K79 methylation associated with IDH mutations support the proliferation of leukemias dependent on this mark. However, we found that mIDH1/2 and KMT2A alterations failed to cooperate in an experimental model. Instead, mIDH1/2 and 2-hydroxyglutarate exert toxic effects, specifically on KMT2A-rearranged AML cells (fusions/partial tandem duplications). Mechanistically, we uncover an epigenetic barrier to efficient cooperation; mIDH1/2 expression is associated with high global histone 3 lysine 79 dimethylation (H3K79me2) levels, whereas global H3K79me2 is obligate low in KMT2A-rearranged AML. Increasing H3K79me2 levels, specifically in KMT2A-rearrangement leukemias, resulted in transcriptional downregulation of KMT2A target genes and impaired leukemia cell growth. Our study details a complex genetic and epigenetic interaction of 2 classes of oncogenes, IDH1/2 mutations and KMT2A rearrangements, that is unexpected based on the high percentage of IDH mutations in KMT2APTD AML. KMT2A rearrangements are associated with a trend toward lower response rates to mIDH1/2 inhibitors. The substantial adaptation that has to occur for 2 initially counteracting mutations to be tolerated within the same leukemic cell may provide at least a partial explanation for this observation.

Evaluating Mechanisms of IDH1 Regulation through Site-Specific Acetylation Mimics

Isocitrate dehydrogenase (IDH1) catalyzes the reversible NADP⁺-dependent oxidation of isocitrate to α-ketoglutarate (αKG). IDH1 mutations, primarily R132H, drive > 80% of low-grade gliomas and secondary glioblastomas and facilitate the NADPH-dependent reduction of αKG to the oncometabolite D-2-hydroxyglutarate (D2HG). While the biochemical features of human WT and mutant IDH1 catalysis have been well-established, considerably less is known about mechanisms of regulation. Proteomics studies have identified lysine acetylation in WT IDH1, indicating post-translational regulation. Here, we generated lysine to glutamine acetylation mimic mutants in IDH1 to evaluate the effects on activity. We show that mimicking lysine acetylation decreased the catalytic efficiency of WT IDH1, with less severe catalytic consequences for R132H IDH1.

Molecular mechanisms mediating relapse following ivosidenib monotherapy in IDH1-mutant relapsed or refractory AML

Isocitrate dehydrogenase (IDH) 1 and 2 mutations result in overproduction of D-2-hydroxyglutarate (2-HG) and impaired cellular differentiation. Ivosidenib, a targeted mutant IDH1 (mIDH1) enzyme inhibitor, can restore normal differentiation and results in clinical responses in a subset of patients with mIDH1 relapsed/refractory (R/R) acute myeloid leukemia (AML). We explored mechanisms of ivosidenib resistance in 174 patients with confirmed mIDH1 R/R AML from a phase 1 trial. Receptor tyrosine kinase (RTK) pathway mutations were associated with primary resistance to ivosidenib. Multiple mechanisms contributed to acquired resistance, particularly outgrowth of RTK pathway mutations and 2-HG-restoring mutations (second-site IDH1 mutations, IDH2 mutations). Observation of multiple concurrent mechanisms in individual patients underscores the complex biology of resistance and has important implications for rational combination therapy design. This trial was registered at www.clinicaltrials.gov as #NCT02074839.

Molecular and morphological changes induced by ivosidenib correlate with efficacy in mutant-IDH1 cholangiocarcinoma

Background: IDH1 mutations occur in approximately 13% of intrahepatic cholangiocarcinomas (IHCCs). The oral, targeted, mutant IDH1 (mIDH1) inhibitor ivosidenib (AG-120) suppresses production of the oncometabolite D-2-hydroxyglutarate, promoting disease stabilization and improved progression-free survival (PFS) in mIDH1 IHCC. Materials & methods: Harnessing matched baseline and on-treatment biopsies, we investigate the potential mechanisms underlying ivosidenib's efficacy. Results: mIDH1 inhibition leads to decreased cytoplasm and expression of hepatocyte lineage markers in patients with prolonged PFS. These findings are accompanied by downregulation of biliary fate, cell cycle progression and AKT pathway activity. Conclusion: Ivosidenib stimulates a hepatocyte differentiation program in mIDH1 IHCC, a phenotype associated with clinical benefit. mIDH1 inhibition could be a paradigm for differentiation-based therapy in solid tumors. Clinical trial registration: NCT02073994 (ClinicalTrials.gov).

A Review of Multiple Venous Malformations of the Upper Limb: Classification, Genetics, and Pathogenesis

Venous (cavernous) malformations are commonly seen in the upper limb. There is no consensus in the literature regarding the classification of venous malformations. Patients may be viewed as 2 clinical entities: patients with single or multiple lesions. Single venous malformations are sporadic and nonsyndromic, whereas the presence of multiple malformations indicates the presence of either an inherited or an overgrowth (noninherited) disorder. In this article, the author reviews multiple venous malformations of the upper limb, offers a novel classification, and describes their clinical entities along with their genetics and pathogenesis. These clinical entities will also be described by categorizing the cases as per the clinical presentation. Furthermore, the number of cases seen by the author (during an experience of 28 years of practice in Saudi Arabia) in each category will be reviewed to give the reader an overall view of the frequency of presentation of each category to the hand/plastic surgery clinic. Clinically, patients may present in 4 different presentations depending on the distribution of the lesions: the late-onset malformations confined to the upper limb; malformations involving the limbs/face/trunk with no mucosal lesions; widespread malformations of the skin, oral mucosa, and the intestine; and venous malformations presenting as a well-known syndrome. The author has seen a total of 84 patients, and the most 2 common presentations were late-onset type (n = 26) and malformations involving the limbs/face/trunk with no mucosal lesions (n = 36). This is the most comprehensive review of multiple venous malformations of the upper limb.

Proteins moonlighting in tumor metabolism and epigenetics

Cancer development is a complicated process controlled by the interplay of multiple signaling pathways and restrained by oxygen and nutrient accessibility in the tumor microenvironment. High plasticity in using diverse nutrients to adapt to metabolic stress is one of the hallmarks of cancer cells. To respond to nutrient stress and to meet the requirements for rapid cell proliferation, cancer cells reprogram metabolic pathways to take up more glucose and coordinate the production of energy and intermediates for biosynthesis. Such actions involve gene expression and activity regulation by the moonlighting function of oncoproteins and metabolic enzymes. The signal - moonlighting protein - metabolism axis facilitates the adaptation of tumor cells under varying environment conditions and can be therapeutically targeted for cancer treatment.

Current biomarker-associated procedures of cancer modeling-a reference in the context of IDH1 mutant glioma

Isocitrate dehydrogenases (IDH1/2) are central molecular markers for glioblastoma. Providing in vitro or in vivo models with mutated IDH1/2 can help prepare facilities to understand the biology of these mutated genes as glioma markers, as well as help, improve therapeutic strategies. In this review, we first summarize the biology principles of IDH and its mutations and outline the core primary findings in the clinical context of neuro-oncology. Given the extensive research interest and exciting developments in current stem cell biology and genome editing, the central part of the manuscript is dedicated to introducing various routes of disease modeling strategies of IDH mutation (IDHMut) glioma and comparing the scientific-technological findings from the field using different engineering methods. Lastly, by giving our perspective on the benefits and limitations of patient-derived and donor-derived disease modeling respectively, we aim to propose leading research questions to be answered in the context of IDH1 and glioma.

LncRNA IDH1-AS1 suppresses cell proliferation and tumor growth in glioma

Glioma is a type of brain tumor that is common globally, and is associated with a variety of genetic changes. It has been reported that isocitrate dehydrogenase 1 (IDH1) is overexpressed in glioma and in HeLa cells. The lncRNA IDH1-AS1 is believed to interact with IDH1, and when IDH1-AS1 is overexpressed, HeLa cell proliferation is inhibited. However, the effects of IDH1-AS1 on glioma were relatively unknown. The results from this work show that IDH1-AS1 is downregulated in the glioma tissues. We used primary glioblastoma cell lines U251 and U87-MG to study the effects of IDH1-AS1 on glioma cell growth, in vitro and in vivo. We found that when IDH1-AS1 is overexpressed cell proliferation is inhibited, cell cycle is arrested at the G1 phase, and the protein expression levels of cyclinD1, cyclinA, cyclinE, CDK2, and CDK4 are decreased. We found that cell apoptosis was increased when IDH1-AS1 was overexpressed, as evidenced by increases in the levels of cleaved caspase-9 and -3. Conversely, knockdown of IDH1-AS1 promoted cell proliferation. Moreover, we proved that overexpression of IDH1-AS1 inhibits the tumorigenesis of U251 cells, in vivo. Furthermore, IDH1-AS1 did not affect IDH1 protein expression, but altered its enzymatic activities in glioma cells. Silencing of IDH1 reversed the effects of IDH1-AS1 upregulation on cell viability. Hence, our study provides first-hand evidence for the effects of lncRNA IDH1-AS1 on gliomas. Because overexpressing IDH1-AS1 inhibited cell growth, IDH1-AS1 could also be considered as a potential target for glioma treatment.

Identifying Genomic Alterations in Patients With Stage IV Breast Cancer Using MammaSeq: An International Collaborative Study

BACKGROUND

Identification of genomic alterations present in cancer patients may aid in cancer diagnosis, prognosis and therapeutic target discovery. In this study, we aimed to identify clinically actionable variants present in stage IV breast cancer (BC) samples.

MATERIALS AND METHODS

DNA was extracted from formalin-fixed paraffin-embedded samples of BC (n = 41). DNA was sequenced using MammaSeq, a BC-specific next-generation sequencing panel targeting 79 genes and 1369 mutations. Ion Torrent Suite 4.0 was used to make variant calls on the raw data, and the resulting single nucleotide variants were annotated using the CRAVAT toolkit. Single nucleotide variations (SNVs) were filtered to remove common polymorphisms and germline variants. CNVkit was employed to identify copy number variations (CNVs). The Precision Medicine Knowledgebase (PMKB) and OncoKB Precision Oncology Database were used to associate clinical significance with the identified variants.

RESULTS

A total of 41 samples from Turkish patients with BC were sequenced (read depth of 94-13,340; median of 1529). These patients were diagnosed with various BC subtypes including invasive ductal carcinoma, invasive lobular carcinoma, apocrine BC, and micropapillary BC. In total, 59 different alterations (49 SNVs and 10 CNVs) were identified. From these, 8 alterations (3 CNVs - ERBB2, FGFR1, and AR copy number gains and 5 SNVs - IDH1.R132H, TP53.E204∗, PI3KCA.E545K, PI3KCA.H1047R, and PI3KCA.R88Q) were identified to have some clinical significance by PMKB and OncoKB. Moreover, the top 5 genes with the most SNVs included PIK3CA, TP53, MAP3K1, ATM, and NCOR1. Additionally, copy number gains and losses were found in ERBB2, GRB7, IGFR1, AR, FGFR1, MYC, and IKBKB, and BRCA2, RUNX1, and RB1, respectively.

CONCLUSION

We identified 59 unique alterations in 38 genes in 41 stage IV BC tissue samples using MammaSeq^TM. Eight of these alterations were found to have some clinical significance by OncoKB and PKMB. This study highlights the potential use of cancer specific next-generation sequencing panels in clinic to get better insight into the patient-specific genomic alterations.

Wild‑type IDH1 affects cell migration by modulating the PI3K/AKT/mTOR pathway in primary glioblastoma cells

Glioblastoma (GBM) is the most common type of brain cancer and has the highest mortality. Dysregulated expression of wild-type isocitrate dehydrogenase 1 (IDH1) has been demonstrated to promote the progression of primary GBM without accumulating D-2-hydroxyglutarate, which differs from IDH1 mutation-related mechanisms of tumorigenesis. Previous studies have revealed several roles of wild-type IDH1 in primary GBM, involving proliferation and apoptosis. However, the function of IDH1 in cell migration has not been investigated. In the current study, the results of bioinformatics analysis revealed that IDH1 expression was significantly upregulated in patients with primary GBM. Wound healing and Transwell assays demonstrated that IDH1 overexpression promoted cell migration in primary GBM cells and that IDH1 knockdown hindered this process. Furthermore, α-ketoglutarate (α-KG), which is the main product of IDH1-catalyzed reactions, was significantly decreased by IDH1 knockdown and upregulated by IDH1 overexpression. α-KG treatment significantly increased the migration of primary GBM cells. Additionally, RNA sequence analysis of patients with primary GBM reported significant alterations in the expression of phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway-regulated genes, including Myc, Snail family transcriptional repressor 2 and Twist-related protein 1, which are primarily cell migration regulatory factors. Western blotting revealed that the overexpression or knockdown of IDH1 promoted or inhibited the PI3K/AKT/mTOR pathway, respectively. α-KG treatment of primary GBM cells also promoted the PI3K/AKT/mTOR pathway. Furthermore, IDH1-overexpressing and α-KG-treated U87 cells were incubated with rapamycin, an mTOR-specific inhibitor, and the results revealed that rapamycin treatment reversed the increased cell migration caused by IDH1 overexpression and α-KG treatment. The results indicated that IDH1 regulated the migration of primary GBM cells by altering α-KG levels and that the function of the IDH1/α-KG axis may rely on PI3K/AKT/mTOR pathway regulation.

Mitochondria in cancer

The rediscovery and reinterpretation of the Warburg effect in the year 2000 occulted for almost a decade the key functions exerted by mitochondria in cancer cells. Until recent times, the scientific community indeed focused on constitutive glycolysis as a hallmark of cancer cells, which it is not, largely ignoring the contribution of mitochondria to the malignancy of oxidative and glycolytic cancer cells, being Warburgian or merely adapted to hypoxia. In this review, we highlight that mitochondria are not only powerhouses in some cancer cells, but also dynamic regulators of life, death, proliferation, motion and stemness in other types of cancer cells. Similar to the cells that host them, mitochondria are capable to adapt to tumoral conditions, and probably to evolve to ‘oncogenic mitochondria' capable of transferring malignant capacities to recipient cells. In the wider quest of metabolic modulators of cancer, treatments have already been identified targeting mitochondria in cancer cells, but the field is still in infancy.

Durable complete responses in some recurrent high-grade glioma patients treated with Toca 511 + Toca FC

Background

Vocimagene amiretrorepvec (Toca 511) is an investigational gamma-retroviral replicating vector encoding cytosine deaminase that, when used in combination with extended-release 5-fluorocytosine (Toca FC), results preclinically in local production of 5-fluorouracil, depletion of immune-suppressive myeloid cells, and subsequent induction of antitumor immunity. Recurrent high-grade glioma (rHGG) patients have a high unmet need for effective therapies that produce durable responses lasting more than 6 months. In this setting, relapse is nearly universal and most responses are transient.

Methods

In this Toca 511 ascending-dose phase I trial (NCT01470794), HGG patients who recurred after standard of care underwent surgical resection and received Toca 511 injected into the resection cavity wall, followed by orally administered cycles of Toca FC.

Results

Among 56 patients, durable complete responses were observed. A subgroup was identified based on Toca 511 dose and entry requirements for the follow-up phase III study. In this subgroup, which included both isocitrate dehydrogenase 1 (IDH1) mutant and wild-type tumors, the durable response rate is 21.7%. Median duration of follow-up for responders is 35.7+ months. As of August 25, 2017, all responders remain in response and are alive 33.9+ to 52.2+ months after Toca 511 administration, suggesting a positive association of durable response with overall survival.

Conclusions

Multiyear durable responses have been observed in rHGG patients treated with Toca 511 + Toca FC in a phase I trial, and the treatment will be further evaluated in a randomized phase III trial. Among IDH1 mutant patients treated at first recurrence, there may be an enrichment of complete responders.

Wild-Type IDH Enzymes as Actionable Targets for Cancer Therapy

Isocitrate dehydrogenases (IDHs) are enzymes that catalyze the oxidative decarboxylation of isocitrate, producing α-ketoglutarate (αKG) and CO₂. The discovery of IDH1 and IDH2 mutations in several malignancies has brought to the approval of drugs targeting IDH1/2 mutants in cancers. Here, we summarized findings addressing the impact of IDH mutants in rare pathologies and focused on the relevance of non-mutated IDH enzymes in tumors. Several pieces of evidence suggest that the enzymatic inhibition of IDHs may have therapeutic potentials also in wild-type IDH cancers. Moreover, IDHs inhibition could enhance the efficacy of canonical cancer therapies, such as chemotherapy, target therapy, and radiotherapy. However, further studies are required to elucidate whether IDH proteins are diagnostic/prognostic markers, instrumental for tumor initiation and maintenance, and could be exploited as targets for anticancer therapy. The development of wild-type IDH inhibitors is expected to improve our understanding of a potential non-oncogenic addition to IDH1/2 activities and to fully address their applicability in combination with other therapies.

Identification of novel mutational drivers reveals oncogene dependencies in multiple myeloma

Understanding the profile of oncogene and tumor suppressor gene mutations with their interactions and impact on the prognosis of multiple myeloma (MM) can improve the definition of disease subsets and identify pathways important in disease pathobiology. Using integrated genomics of 1273 newly diagnosed patients with MM, we identified 63 driver genes, some of which are novel, including IDH1, IDH2, HUWE1, KLHL6, and PTPN11 Oncogene mutations are significantly more clonal than tumor suppressor mutations, indicating they may exert a bigger selective pressure. Patients with more driver gene abnormalities are associated with worse outcomes, as are identified mechanisms of genomic instability. Oncogenic dependencies were identified between mutations in driver genes, common regions of copy number change, and primary translocation and hyperdiploidy events. These dependencies included associations with t(4;14) and mutations in FGFR3, DIS3, and PRKD2; t(11;14) with mutations in CCND1 and IRF4; t(14;16) with mutations in MAF, BRAF, DIS3, and ATM; and hyperdiploidy with gain 11q, mutations in FAM46C, and MYC rearrangements. These associations indicate that the genomic landscape of myeloma is predetermined by the primary events upon which further dependencies are built, giving rise to a nonrandom accumulation of genetic hits. Understanding these dependencies may elucidate potential evolutionary patterns and lead to better treatment regimens.

Signaling Pathways Involved in the Regulation of mRNA Translation

Translation is a key step in the regulation of gene expression and one of the most energy-consuming processes in the cell. In response to various stimuli, multiple signaling pathways converge on the translational machinery to regulate its function. To date, the roles of phosphoinositide 3-kinase (PI3K)/AKT and the mitogen-activated protein kinase (MAPK) pathways in the regulation of translation are among the best understood. Both pathways engage the mechanistic target of rapamycin (mTOR) to regulate a variety of components of the translational machinery. While these pathways regulate protein synthesis in homeostasis, their dysregulation results in aberrant translation leading to human diseases, including diabetes, neurological disorders, and cancer. Here we review the roles of the PI3K/AKT and MAPK pathways in the regulation of mRNA translation. We also highlight additional signaling mechanisms that have recently emerged as regulators of the translational apparatus.

The role of amino-acid PET in the light of the new WHO classification 2016 for brain tumors

Since its introduction in 2016, the revision of the World Health Organization (WHO) classification of central nervous system tumors has already changed the diagnostic and therapeutic approach in glial tumors. Blurring the lines between entities formerly labelled as "high-grade" or "low-grade", molecular markers define distinct biological subtypes with different clinical course. This new classification raises the demand for non-invasive imaging methods focusing on depicting metabolic processes. We performed a review of current literature on the use of amino-acid PET (AA-PET) for obtaining diagnostic or prognostic information on glioma in the setting of the current WHO 2016 classification. So far, only a few studies have focused on combining molecular genetic information and metabolic imaging using AA-PET. The current review summarizes the information available on "molecular grading" as well as prognostic information obtained from AA-PET and delivers an insight into a possible interrelation between metabolic imaging and glioma genetics. Within the framework of molecular characterization of gliomas, metabolic imaging using AA-PET is a promising tool for non-invasive characterization of molecular features and to provide additional prognostic information. Further studies incorporating molecular and metabolic features are necessary to improve the explanatory power of AA-PET in glial tumors.

Wild-type and mutated IDH1/2 enzymes and therapy responses

Isocitrate dehydrogenase 1 and 2 (IDH1/2) are key enzymes in cellular metabolism, epigenetic regulation, redox states, and DNA repair. IDH1/2 mutations are causal in the development and/or progression of various types of cancer due to supraphysiological production of d-2-hydroxyglutarate. In various tumor types, IDH1/2-mutated cancers predict for improved responses to treatment with irradiation or chemotherapy. The present review discusses the molecular basis of the sensitivity of IDH1/2-mutated cancers with respect to the function of mutated IDH1/2 in cellular processes and their interactions with novel IDH1/2-mutant inhibitors. Finally, lessons learned from IDH1/2 mutations for future clinical applications in IDH1/2 wild-type cancers are discussed.

IDH1R132H Promotes Malignant Transformation of Benign Prostatic Epithelium by Dysregulating MicroRNAs: Involvement of IGF1R-AKT/STAT3 Signaling Pathway

Risk stratification using molecular features could potentially help distinguish indolent from aggressive prostate cancer (PCa). Mutations in isocitrate dehydrogenase (IDH) acquire an abnormal enzymatic activity, resulting in the production of 2-hydroxyglutarate and alterations in cellular metabolism, histone modification, and DNA methylation. Mutant IDH1 has been identified in various human malignancies, and IDH1R132H constituted the vast majority of mutational events of IDH1. Most recent studies suggested that IDH1 mutations define a methylator subtype in PCa. However, the function of IDH1R132H in PCa development and progression is largely unknown. In this study, we showed that the prevalence of IDH1R132H in Chinese PCa patients is 0.6% (2/336). Of note, IDH1R132H-mutant PCa patients lacked other canonical genomic lesions (e.g., ERG rearrangement, PTEN deletion) that are common in most other PCa patients. The in vitro experiment suggested that IDH1R132H can promote proliferation of benign prostate epithelial cell RWPE-1 when under the situation of low cytokine. It could also promote migration capacity of RWPE-1 cells. Mechanistically, IDH1R132H was an important regulator of insulin-like growth factor 1receptor (IGF1R) by downregulating a set of microRNAs (miR-141-3p, miR-7-5p, miR-223-3p). These microRNAs were repressed by the alteration of epigenetic modification to decrease the enrichment of active marker H3K4me3 or to increase repressive marker H3K27me3 at their promoters. Collectively, we proposed a novel model for an IDH1R132H-microRNAs-IGF1R regulatory axis, which might provide insight into the function of IDH1R132H in PCa development.

Overexpression of mTOR and p(240-244)S6 in IDH1 Wild-Type Human Glioblastomas Is Predictive of Low Survival

PI3K/Akt/mTOR pathway activation is a hallmark of high-grade gliomas, which prompted clinical trials for the use of PI3K and mTOR inhibitors. However, the poor results in the original trials suggested that better patient profiling was needed for such drugs. Thus, accurate and reproducible monitoring of mTOR complexes can lead to improved therapeutic strategies. In this work, we evaluated the expression and phosphorylation of mTOR, RAPTOR, and rpS6 in 195 human astrocytomas and 30 normal brain tissue samples. The expression of mTOR increased in glioblastomas, whereas mTOR phosphorylation, expression of RAPTOR, and expression and phosphorylation of rpS6 were similar between grades. Interestingly, the overexpression of total and phosphorylated mTOR as well as phosphorylated rpS6 (residues 240-244) were associated with wild-type IDH1 only glioblastomas. The expression and phosphorylation of mTOR and phosphorylation of rpS6 at residues 240-244 were associated with a worse prognosis in glioblastomas. Our results suggest that mTOR and rpS6 could be used as markers of overactivation of the PI3K-mTOR pathway and are predictive factors for overall survival in glioblastomas. Our study thus suggests that patients who harbor IDH1 wild-type glioblastomas might have increased benefit from targeted therapy against mTOR.

Isocitrate dehydrogenase 1 mutation subtypes at site 132 and their translational potential in glioma

In recent years, de novo missense structural mutations in the IDH1 gene of arginine at site 132 (R132) have become a standard for diagnostication and prognostication in glioma management. As our clinical understanding of this mutation grows, so too does the number of mutation subtypes reported in the literature. By synergizing current knowledge of IDH1 activity in glioma with the emerging evidence of different enzyme kinetics between R132 IDH1 mutation subtypes, the translational potential in improving glioma management based on mutated IDH1 subtype in glioma is described.

Molecular Subgroups of Glioblastoma- an Assessment by Immunohistochemical Markers

Comprehensive molecular characterization of and novel therapeutic approaches to glioblastoma have been explored as a result of advancements in biotechnologies. In this study, we aimed to bring basic research discoveries closer to clinical practice and ultimately incorporate molecular classification into the routine histopathological evaluation of grade IV gliomas. Integrated results of genome-wide sequencing, transcriptomic and epigenomic analyses by The Cancer Genome Atlas Network defined the classic, proneural, neural and mesenchymal subtypes of this tumor. In a retrospective cohort, we analyzed selected subgroup-defining molecular markers in formalin-fixed paraffin-embedded surgical specimens by immunohistochemistry. Quantitative and qualitative scores of marker expression were tested in hierarchical cluster analyses to evaluate segregations of the molecular subgroups, which then were correlated with clinical parameters including patients' age, gender and overall survival. Our study has confirmed the separation of molecular glioblastoma subgroups with clear trends regarding clinical correlations. Future analyses in a larger, prospective cohort using similar methods are expected to facilitate the development of a molecular diagnostic panel that may complement routine histological work up and support prognostication as well as treatment decisions in glioblastoma.

Oncogenic Activities of IDH1/2 Mutations: From Epigenetics to Cellular Signaling

Gliomas and leukemias remain highly refractory to treatment, thus highlighting the need for new and improved therapeutic strategies. Mutations in genes encoding enzymes involved in the tricarboxylic acid (TCA) cycle, such as the isocitrate dehydrogenases 1 and 2 (IDH1/2), are frequently encountered in astrocytomas and secondary glioblastomas, as well as in acute myeloid leukemias; however, the precise molecular mechanisms by which these mutations promote tumorigenesis remain to be fully characterized. Gain-of-function mutations in IDH1/2 have been shown to stimulate production of the oncogenic metabolite R-2-hydroxyglutarate (R-2HG), which inhibits α-ketoglutarate (αKG)-dependent enzymes. We review recent advances on the elucidation of oncogenic functions of IDH1/2 mutations, and of the associated oncometabolite R-2HG, which link altered metabolism of cancer cells to epigenetics, RNA methylation, cellular signaling, hypoxic response, and DNA repair.

Rapamycin (mTORC1 inhibitor) reduces the production of lactate and 2-hydroxyglutarate oncometabolites in IDH1 mutant fibrosarcoma cells

BACKGROUND

Multiple studies concluded that oncometabolites (e.g. D-2-hydroxyglutarate (2-HG) related to mutant isocitrate dehydrogenase 1/2 (IDH1/2) and lactate) have tumour promoting potential. Regulatory mechanisms implicated in the maintenance of oncometabolite production have great interest. mTOR (mammalian target of rapamycin) orchestrates different pathways, influences cellular growth and metabolism. Considering hyperactivation of mTOR in several malignancies, the question has been addressed whether mTOR operates through controlling of oncometabolite accumulation in metabolic reprogramming.

METHODS

HT-1080 cells - carrying originally endogenous IDH1 mutation - were used in vitro and in vivo. Anti-tumour effects of rapamycin were studied using different assays. The main sources and productions of the oncometabolites (2-HG and lactate) were analysed by ¹³C-labeled substrates. Alterations at protein and metabolite levels were followed by Western blot, flow cytometry, immunohistochemistry and liquid chromatography mass spectrometry using rapamycin, PP242 and different glutaminase inhibitors, as well.

RESULTS

Rapamycin (mTORC1 inhibitor) inhibited proliferation, migration and altered the metabolic activity of IDH1 mutant HT-1080 cells. Rapamycin reduced the level of 2-HG sourced mainly from glutamine and glucose derived lactate which correlated to the decreased incorporation of ¹³C atoms from ¹³C-substrates. Additionally, decreased expressions of lactate dehydrogenase A and glutaminase were also observed both in vitro and in vivo.

CONCLUSIONS

Considering the role of lactate and 2-HG in regulatory network and in metabolic symbiosis it could be assumed that mTOR inhibitors have additional effects besides their anti-proliferative effects in tumours with glycolytic phenotype, especially in case of IDH1 mutation (e.g. acute myeloid leukemias, gliomas, chondrosarcomas). Based on our new results, we suggest targeting mTOR activity depending on the metabolic and besides molecular genetic phenotype of tumours to increase the success of therapies.