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Vorobeva, M.

Publications and source records attributed to Vorobeva, M..

3 recordsLinked to original sources

Preclinical evaluation of Brincidofovir in glioblastoma demonstrates improved long term-survival and cytomegalovirus-dependent and independent effects

Cytomegalovirus (CMV) has been implicated in glioblastoma (GBM) progression. Ongoing clinical trials are assessing therapeutic approaches targeting CMV in GBM but to date no new therapy has been approved outside the standard of care. Previous preclinical studies have highlighted the potential of the antiviral drug Cidofovir (CDV) in GBM; however, its clinical use is limited by dose-dependent nephrotoxicity and poor cellular uptake, necessitating high intravenous doses to achieve therapeutic activity. Brincidofovir (BCV), a lipid conjugate of CDV has been developed, which does not induce nephrotoxicity and has significantly greater cellular bioavailability. Here we examined the effects of BCV in a newly established CMV-driven GBM model (SB28) and in patient-derived tumor neurospheres. We show that BCV prolongs survival in vivo and exerts both CMV-dependent and independent antitumor effects. Mechanistically, BCV induces DNA damage and cell cycle dysregulation in GBM cells and inhibits proliferation of patient-derived neurospheres in a dose-dependent manner. These data identify BCV as a dual-action therapeutic that suppresses viral oncomodulation while directly targeting tumor cell viability.

cancer biology↗

Ancestral intronic splicing regulatory elements in the SCNα gene family

SCN genes encode components of voltage-gated sodium channels that are crucial for generating electrical signals. Humans have ten paralogous SCN genes, some of which contain duplicated mutually exclusive exons 5a and 5b. In reconstructing their evolutionary history, we found multiple unannotated copies of exon 5 in distant species and showed that exon 5 duplication goes back to a common ancestor of the SCN gene family. We char-acterized splicing patterns of exons 5a and 5b across tissues, tumors, and developmental stages, and demonstrated that the nonsense mediated decay (NMD) system is not the ma-jor factor contributing to their mutually exclusive choice. Comparison of SCN2A, SCN3A, SCN5A, and SCN9A intronic nucleotide sequences revealed multiple Rbfox2 binding sites and two highly conserved intronic splicing regulatory elements (ISRE) that are shared be-tween paralogs. Minigene mutagenesis and blockage by antisense oligonucleotides showed that the formation of RNA structure between ISRE promotes exon 5b skipping in SCN9A. The inclusion of exon 5b is also suppressed in siRNA-mediated knockdown of Rbfox2, which makes the collective action of RNA structure and Rbfox2 compatible with the model of a structural RNA bridge. ISRE sequences are conserved from human to elephant shark and may represent an ancient, evolutionarily conserved regulatory mechanism. Our results demonstrate the power of comparative sequences analysis in application to paralogs for elucidating splicing regulatory programs.

bioinformatics↗

BRD2 and BRD3 genes independently evolved RNA structures to control unproductive splicing

The mammalian BRD2 and BRD3 genes encode structurally related proteins from the bromodomain and extraterminal domain (BET) protein family. The expression of BRD2 is regulated by unproductive splicing upon inclusion of exon 3b, which is located in the region encoding a bromodomain. Bioinformatic analysis indicated that BRD2 exon 3b inclusion is controlled by a pair of conserved complementary regions (PCCR) located in the flanking introns. Furthermore, we identified a highly conserved element encoding a cryptic poison exon 5b and a previously unknown PCCR in the intron between exons 5 and 6 of BRD3, however outside of the homologous bromodomain. Minigene mutagenesis and blockage of RNA structure by antisense oligonucleotides demonstrated that RNA structure controls the rate of inclusion of poison exons. The patterns of BRD2 and BRD3 expression and splicing show downregulation upon inclusion of poison exons, which become skipped in response to transcription elongation slowdown, further confirming a role of PCCRs in unproductive splicing regulation. We conclude that BRD2 and BRD3 independently acquired poison exons and RNA structures to dynamically control unproductive splicing. This study describes a convergent evolution of regulatory unproductive splicing mechanisms in these genes providing implications for selective modulation of their expression in therapeutic applications.

bioinformatics↗