Epigenetic mechanisms such as DNA methylation are essential regulators of the function and information storage capacity of neurons. DNA methylation is highly dynamic in the developing and adult brain, and is actively regulated by neuronal activity and behavioural experiences. However, it is presently unclear how methylation status at individual genes is targeted for modification. Here, we report that extra-coding RNAs (ecRNAs) interact with DNA methyltransferases and regulate neuronal DNA methylation. Expression of ecRNA species is associated with gene promoter hypomethylation, is altered by neuronal activity, and is overrepresented at genes involved in neuronal function. Knockdown of the Fos ecRNA locus results in gene hypermethylation and mRNA silencing, and hippocampal expression of Fos ecRNA is required for long-term fear memory formation in rats. These results suggest that ecRNAs are fundamental regulators of DNA methylation patterns in neuronal systems, and reveal a promising avenue for therapeutic targeting in neuropsychiatric disease states.

Glioblastoma (GBM) remains the most devastating primary central nervous system malignancy with a median survival of around 15 months. The past decades of research have not yielded significant advancements in the treatment of GBM. In that same time, a novel class of molecules, long non-coding RNAs (lncRNAs), has been found to play a multitude of roles in cancer and normal biology. The increased accessibility of next generation sequencing technologies and the advent of lncRNA-specific microarrays have facilitated the study of lncRNA etiology. Molecular and computational methods can be applied to predict lncRNA function. LncRNAs can serve as molecular decoys, scaffolds, super-enhancers, or repressors. These molecules can serve as phenotypic switches for GBM cells at the expression and/or epigenetic levels. LncRNAs can affect stemness/differentiation, proliferation, invasion, survival, DNA damage response, and chromatin dynamics. Aberrant expression of these transcripts may facilitate therapy resistance, leading to tumor recurrence. LncRNAs could serve as novel theragnostic or prognostic biomarkers in GBM and other cancers. RNA-based therapeutics may also be employed to target lncRNAs as a novel route of treatment for primary or recurrent GBM. In this review, we explore the roles of lncRNAs in GBM pathophysiology and posit their novel therapeutic potential for GBM.

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Key molecular regulators of acquired radiation resistance in recurrent glioblastoma (GBM) are largely unknown with a dearth of accurate pre-clinical models. To address this, we generated 8 GBM patient-derived xenograft (PDX) models of acquired radiation therapy-selected (RTS) resistance compared with same-patient, treatment naïve (RTU) PDX. These unique models mimic the longitudinal evolution of patient recurrent tumors following serial radiation therapy. Indeed, while whole exome sequencing confirmed retention of major genomic alterations in the RTS lines, we did detect a chromosome 12q14 amplification that is associated with clinical GBM recurrence in two RTS models. A novel bioinformatics pipeline was applied to analyze phenotypic, transcriptomic and kinomic alterations, which identified long non-coding RNAs (lncRNAs) and targetable, PDX-specific kinases. We observed differential transcriptional enrichment of DNA damage repair (DDR) pathways in our RTS models which correlated with several lncRNAs. Global kinomic profiling separated RTU and RTS models, but pairwise analyses indicated that there are multiple molecular routes to acquired radiation-resistance. RTS model-specific kinases were identified and targeted with clinically relevant small molecule inhibitors (SMIs). This unique cohort of in vivo radiation therapy-selected patient-derived models will enable future preclinical therapeutic testing to help overcome the treatment resistance seen in GBM patients.

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