Targeting mTOR as a Therapeutic Approach in Medulloblastoma

Mechanistic target of rapamycin (mTOR) is a master signaling pathway that regulates organismal growth and homeostasis, because of its implication in protein and lipid synthesis, and in the control of the cell cycle and the cellular metabolism. Moreover, it is necessary in cerebellar development and stem cell pluripotency maintenance. Its deregulation has been implicated in the medulloblastoma and in medulloblastoma stem cells (MBSCs). Medulloblastoma is the most common malignant solid tumor in childhood. The current therapies have improved the overall survival but they carry serious side effects, such as permanent neurological sequelae and disability. Recent studies have given rise to a new molecular classification of the subgroups of medulloblastoma, specifying 12 different subtypes containing novel potential therapeutic targets. In this review we propose the targeting of mTOR, in combination with current therapies, as a promising novel therapeutic approach.J.A. is recipient of a predoctoral fellowship from the Department of Education of the Basque Government. This work was supported by grants from the Department of Industry of the Basque Government (SAIO13-PC13BN011), and the European Regional Developmental Fund, Institute of Health Carlos III (ISCIII) (PI16/01730) to I.G

MTHFR polymorphisms in childhood acute lymphoblastic leukemia: influence on methotrexate therapy

Methotrexate (MTX) is an important component in the therapy used to treat childhood acute lymphoblastic leukemia ( ALL). Methylenetetrahydrofolate reductase ( MTHFR) is a key enzyme for MTX pharmacokinetics. Two single-nucleotide polymorphisms in MTHFR gene, C677T and A1298C, affecting MTHFR activity, have been widely studied as potential markers of MTX toxicity and/or outcome in pediatric ALL. In this review, we show that the majority of published reports do not find association or present opposite effect. Therefore, MTHFR C677T and A1298C polymorphisms do not seem to be good markers of MTX-related toxicity and/or outcome in pediatric ALL. The efforts should be focused on other genes, such as transporter genes or microRNA-related genes

Osteosarkoma pediatrikoarekiko suszeptibilitatean inplikatuta dauden aldaera genetikoak

Osteosarcoma (OS) is the most common primary bone cancer that occurs primarily in children, adolescents, and young adults. The fact that OS occurs at an early age suggests that there is a strong genetic component at its source. Several studies have suggested that susceptibility to OS development is due to small common low-pene trance variants, such as SNPs. The implication of the common genetic variants in the susceptibility to cancer has already been demonstrated in several studies. One of the most non-coding RNAs studied in cancer are miRNAs and are known to be involved in the origin and evolution of various cancers. Therefore, we analyzed all the genetic vari-ability of the genes of the miRNAs processing path and their implication in the suscep-tibility of the OS. As a result, we decided to validate the association between the ge-netic variants previously associated with the risk to develop OS and to look for new risk markers in the genes related to the miRNAs. Our results indicated that a SNP in the CTLA4 gene could be a marker of susceptibility to develop OS along with the hotspot in the 14q32 region.; Osteosarkoma (OS) edo sarkoma osteogenikoa gazteen artean gertatzen den hezur-minbizirik ohikoena da. Adin hain goiztiarretan sortzeak adierazten du haren jatorrian genetikak paper garrantzitsua duela. Izan ere, hainbat ikerketa-lanen arabera, sarkortasun txikiko aldaera genetikoak (SNPak, esaterako) OSaren kausa izan ohi dira. Jakina da beste minbizi mota batzuetan aldaera genetikoek gaixotasun horrekiko suszeptibilitatean eragina izaten dutela. miRNAk dira minbizien jatorri eta bilakaeran gehien aztertu diren RNA ez-kodetzaileak (ncRNA). Hori dela eta, bai gune kodetzaileetan bai ez-kodetzaileetan (miRNAk eta hauek prozesatzen dituzten geneak) zen aldakortasun genetikoa aztertu genuen. Lan honetan, OSarekiko suszeptibilitatean eragina duten aldaera genetikoen bilaketa egin genuen. Gure emaitzek CTLA4 genea eta 14q32 guneko miRNA taldeak OSarekiko suszeptibilitatearen hotspot-ak izan daitezkeela erakusten dute

Variants in the 14q32 miRNA cluster are associated with osteosarcoma risk in the Spanish population

Association studies in osteosarcoma risk found significant results in intergenic regions, suggesting that regions which do not codify for proteins could play an important role. The deregulation of microRNAs (miRNAs) has been already associated with osteosarcoma. Consequently, genetic variants affecting miRNA function could be associated with risk. This study aimed to evaluate the involvement of all genetic variants in pre-miRNAs described so far in relationship to the risk of osteosarcoma. We analyzed a total of 213 genetic variants in 206 pre-miRNAs in two cohorts of osteosarcoma patients (n = 100) and their corresponding controls (n = 256) from Spanish and Slovenian populations, using Goldengate Veracode technology (Illumina). Four polymorphisms in pre-miRNAs at 14q32 miRNA cluster were associated with osteosarcoma risk in the Spanish population (rs12894467, rs61992671, rs58834075 and rs12879262). Pathway enrichment analysis including target genes of these miRNAs pointed out the WNT signaling pathways overrepresented. Moreover, different single nucleotide polymorphism (SNP) effects between the two populations included were observed, suggesting the existence of population differences. In conclusion, 14q32 miRNA cluster seems to be a hotspot for osteosarcoma susceptibility in the Spanish population, but not in the Slovenian, which supports the idea of the existence of population differences in developing this disease.Special thanks to Slovenian Osteosarcoma Study Group for their collaboration in sample collection. The "Slovenian Osteosarcoma Study Group" is conformed by Katja Goricar from the Institute of Biochemistry, Faculty of Medicine of Ljubljana, Viljem Kovac from the Pharmacogenetics Laboratory, Institute of Biochemistry, Faculty of Medicine of University of Ljubljana, Janez Jazbec from the Institute of Oncology Ljubljana, Janez Lamovec from the Oncology and Hematology Unit, University Children's Hospital, University Medical Centre of Ljubljana and Prof. Vita Dolzan included in the authorship of this article. The authors would like to thank Leire Iparraguirre for her technical assistance with figures. This study was funded by the Basque Government (IT661-13, IT989-16), UPV/EHU (UFI11/35)

Confirmation of involvement of new variants at CDKN2A/B in pediatric acute lymphoblastic leukemia susceptibility in the Spanish population

The locus CDKN2A/B (9p21.3), which comprises the tumor suppressors genes CDKN2A and CDKN2B and the long noncoding RNA (lncRNA) known as ANRIL (or CDKN2B-AS), was associated with childhood acute lymphoblastic leukemia (ALL) susceptibility in several genome wide association studies (GWAS). However, the variants associated in the diverse studies were different. Recently, new and independent SNPs deregulating the locus function were also identified in association with ALL risk. This diversity in the results may be explained because different variants in each population could alter CDKN2A/B locus function through diverse mechanisms. Therefore, the aim of this study was to determine whether the annotated risk variants in the CDKN2A/B locus affect the susceptibility of B cell precursor ALL (B-ALL) in our Spanish population and explore if other SNPs altering additional regulatory mechanisms could be also involved. We analyzed the four SNPs proposed by GWAs and two additional SNPs in miRNA binding sites in 217 pediatric patients with B-ALL and 330 healthy controls. The SNPs rs2811712, rs3731249, rs3217992 and rs2811709 were associated with B-ALL susceptibility in our Spanish population. ALL subtypes analyses showed that rs2811712 was associated with B-hyperdiploid ALL. These results provide evidence for the influence of genetic variants at CDKN2A/B locus with the risk of developing BALL.This study was funded by the Basque Government (IT661-13, IT989-16), UPV/EHU (UFI11/35). AGC was supported by a pre-doctoral grant from the Basque Government. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Morphine leads to global genome changes in H3K27me3 levels via a Polycomb Repressive Complex 2 (PRC2) self-regulatory mechanism in mESCs

Background: Environmentally induced epigenetic changes can lead to health problems or disease, but the mechanisms involved remain unclear. Morphine can pass through the placental barrier leading to abnormal embryo development. However, the mechanism by which morphine causes these effects and how they sometimes persist into adulthood is not well known. To unravel the morphine-induced chromatin alterations involved in aberrant embryo development, we explored the role of the H3K27me3/PRC2 repressive complex in gene expression and its transmission across cellular generations in response to morphine. Results: Using mouse embryonic stem cells as a model system, we found that chronic morphine treatment induces a global downregulation of the histone modification H3K27me3. Conversely, ChIP-Seq showed a remarkable increase in H3K27me3 levels at specific genomic sites, particularly promoters, disrupting selective target genes related to embryo development, cell cycle and metabolism. Through a self-regulatory mechanism, morphine downregulated the transcription of PRC2 components responsible for H3K27me3 by enriching high H3K27me3 levels at the promoter region. Downregulation of PRC2 components persisted for at least 48 h (4 cell cycles) following morphine removal, though promoter H3K27me3 levels returned to control levels. Conclusions: Morphine induces targeting of the PRC2 complex to selected promoters, including those of PRC2 components, leading to characteristic changes in gene expression and a global reduction in H3K27me3. Following morphine removal, enhanced promoter H3K27me3 levels revert to normal sooner than global H3K27me3 or PRC2 component transcript levels. We suggest that H3K27me3 is involved in initiating morphine-induced changes in gene expression, but not in their maintenance.This study was supported by grants from the Spanish Health Department ISCIII (DTS 18/00142) and University of the Basque Country. IM was supported by fellowship from Basque Government, and MA and IU were supported by fellowship from the University of the Basque Country (UPV/EHU)

Polimorfismo genetikoen analisien meta-analisien erabilgarritasunaren analisi kritikoa

Azken urteotan sortzen ari den itzelezko argitalpen kopurua ikusita, meta-analisiak plazaratzen ari dira, helburu bera duten ikerketa lanen informazioa laburtzeko. Hain zuzen ere, gai jakin baten ikerketa lan desberdinen emaitzak konbinatu nahi dira meta-analisi hauetan erantzunik gabeko galderak argitzeko. Kalitatezko meta-analisiak izateko , berau egiteko pausu guztiak ondo landuta eta deskribatuta egon behar dute. Horregatik, meta-analisien erabilgarritasuna baloratzeko haien irakurketa kritikoa egitea oso beharrezkoa da. Adibide moduan, Liu eta laguntzaileak eta gure taldeak, zenbait ahulezi topatu genituen Wang eta laguntzaileek duela gutxi nazioarteko aldizkari zientifiko batean argitaratutako meta-analisian. Ikerketa lan honetan Wang eta laguntzaileen meta-analisiaren irakurketa kritikoa, literaturaren eguneraketa eta asoziazio ikerketa egin genuen . Wang eta laguntzaileak polimorfismoak osteosarkomaren suszeptibi latearekin asoziatuta zeudela ondorioztatu zuten bitartean, gure kasuan ez genuen asoziaziorik topatu . Hortaz, gure lanaren arabera, polimorfismo hauek osteosarkomaren suszeptibilitatearen markatzaile genetikoak ez direla ondorioztatu genuen. Bide batez, adibide honekin, gaur eguneko meta-analisien irakurketa sakona eta analisien emaitzak zuhur hartu behar ditugula azpimarratu nahi dugu, zenbait lanetan ez baitituzte ezarritako irizpideak betetzen mota honetako ikerketa lanak egiterako orduan

Involvement of SNPs in miR-3117 and miR-3689d2 in Childhood Acute Lymphoblastic Leukemia Risk

Acute lymphoblastic leukemia (ALL) is the most common cancer in children. Numerous studies have shown that microRNAs (miRNAs) could play a role in this disease. Nowadays, more than 2500 miRNAs have been described, that regulate more than 50% of genes, including those involved in B-cell maturation, differentiation and proliferation. Genetic variants in miRNAs can alter their own levels or function, affecting their target gene expression, and then, may affect ALL risk. Therefore, the aim of this study was to determine the role of miRNA genetic variants in B-ALL susceptibility. We analyzed all variants in pre-miRNAs (MAF > 1%) in two independent cohorts from Spain and Slovenia and inferred their functional effect by in silico analysis. SNPs rs12402181 in miR-3117 and rs62571442 in miR-3689d2 were associated with ALL risk in both cohorts, possibly through their effect on MAPK signalling pathway. These SNPs could be novel markers for ALL susceptibility

Meduloblastoma pediatrikoaren pronostikorako markatzaile molekularren identifikazioa

Medulloblastoma is a very heterogeneous malignancy at both clinical and molecular levels. In recent years, thanks to the development of massive and whole genome sequencing techniques, many specific mutations have been discovered within each medulloblastoma subtype. Therefore, this study aimed to design a panel of somatic mutations and genes to allow the early recognition of poor prognosis patients or those that will develop resistance to therapy. With this aim, a systematic review was performed to identify all information available in the literature regarding mutations in genes involved in the development of pediatric medulloblastoma. We searched in PubMed database using the keywords and subject terms (Medulloblastoma*) AND (“mutation*” OR “genetic alteration*” OR “genetic variation*”). The original search provided 588 records, from which 62 were finally selected. Out of the 197 identified genes found in those records, 21 showed mutational frequencies higher than 2% and 5 (TP53, CTNNB1, PTCH1, SUFU and KDM6A) could be useful at diagnosis because of their prognostic value or because they were specific of a single subtype. The analysis of these genes could help achieve more individualized therapies based on molecular profile.; Meduloblastoma klinika eta oinarri molekular heterogeneoa duen minbizia da. Azken urteotan, genoma osoko eta sekuentziazio masiboko teknika molekularren garapenaren ondorioz, meduloblastoma pediatrikoan parte hartzen duten mutazio asko identifikatzea ahalbidetu da. Hortaz, lanaren helburua izan zen meduloblastoma pediatrikoaren pronostikoan edota terapian lagundu dezakeen gene eta mutazio somatikoen panel baten diseinua egitea. Horretarako, meduloblastoma pediatrikoan eragina duten geneei buruzko informazioa duen literaturaren berrikuspen sistematikoa egin zen. Bilaketarako Pubmed datubase bibliografikoa erabili zen, honako termino hauek erabiliz: (Medulloblastoma*) AND ("mutation*" OR "genetic alteration*" OR "genetic variation*"). Berrikuspen bibliografikoaren ondoren, hasieran zeuden 588 artikuluetatik 62 artikulutan 197 gene identifikatu ziren. Horietatik, % 2 baino gehiagoko mutazio-maiztasuna zuten 21 gene aurkitu ziren, eta diagnosiaren momentuan balio pronostikoa edo meduloblastoma azpimoten ezaugarri ziren 5 gene (TP53, CTNNB1, PTCH1, SUFU eta KDM6A). Gene horiek analizatuz gero, profil molekularrean oinarritutako tratamendu indibidualizatuak doitu litezke