Glioblastoma (GBM, or astrocytoma grade IV) brain tumor remains one of the most lethal forms of human cancer and a major unmet need in current oncology. GBM is a highly heterogeneous and multifactorial disease characterized by the wide landscape of mutations and signaling alterations. Thus, most of the developingexperimentaltherapieswilllikelyonlyhelpafractionofpatients.WehavediscoveredmicroRNA- 10b (miR-10b), a regulatory molecule whose transcriptional activation emerges as a unique mechanism sharedbyalmostallgliomas,includingbothhigh-gradeandlow-grade,despitetheirheterogeneity.miR-10b regulates neoplastic transformation of normal glial cells and the growth of malignant gliomas. Moreover, it appearsessentialfortheviabilityofheterogeneousgliomacellsandglioma-initiatingstemcells(GSC).Since miR-10bishighlyexpressedinpracticallyallmalignantgliomas,anditsinhibitionaffectsallgliomasubtypes, miR-10btargetingrepresentsacommontherapeuticstrategyforGBM.Despitethehighlevelsandthecritical role of miR-10b in GBM, how the expression of this molecule, which is silenced in the normal brain, gets activated in gliomagenesis is unknown. Based on our preliminary data, we hypothesize that various aberrationsaccumulatinginthebrainmayconvergeonepigeneticalterationsandreorganizationofthethree- dimensionalstructureofthemiR-10blocus,resultinginitstranscriptionalactivation.Suchstructuralchanges, primarilymediatedbytheCCCTC-bindingfactor(CTCF)andregulatorylongnon-codingRNAtranscripts,will resultintheexposureofmiR-10bpromotertoacorrespondingenhancer,andthusmiR-10bexpression.In thisR01project,wewilltestourhypothesis,investigatetheepigeneticmechanismunderlyingtheactivation ofmiR-10blocusinglioma,andestablishthemiR-10b-locuscenteredmodelofgliomagenesis.
SpecificAim 1 will, therefore, provide the high-resolution analysis of the epigenetic landscape and three-dimensional chromatin conformation of miR-10b locus in normal neuroglial and glioma cells and tissues, and at the differentstagesofneoplastictransformation.Itwillalsoassesshowgeneralizablesuchregulationisinglioma onagenomicscale.
SpecificAim2 willinvestigatefunctionsofmajorregulatoryDNAandRNAelementsin the locus, including the promoter-associated and enhancer-associated RNAs, using a combination of biochemical,geneediting,andimaging-basedapproaches.
SpecificAim3 willmodeltheprocessofthelocus activationandneoplastictransformationofastrocytesandneuroprogenitorsusingcellandanimalmodelsof glioma.Discoveryofthemechanism(s)convergingonmiR-10bexpressioninthebraincortexwillshedlight ontheoriginandetiologyofmalignantglioma.Itmayalsosuggestnewstrategiesforswitchingitoffandnew moleculartargetsfortherapeuticapplications.
Thereisacriticalneedforbetterunderstandingofmoleculareventsunderlyinggliomagenesis,aprocessleadingto most aggressive primary brain tumors. miR-10b emerged as a common regulator involved in neoplastic transformation of glial cells, glioma growth, and survival. This project will investigate epigenetic mechanisms of miR-10bactivationinthebrainandtherebyadvanceourunderstandingofbraintumorsandmayopenthedoorfor newtherapeuticapproaches.
