Stress-induced lncRNA LASTR fosters cancer cell fitness by regulating the activity of the U4/U6 recycling factor SART3

Dysregulated splicing is a common event in cancer even in the absence of mutations in the core splicing machinery. The aberrant long non-coding transcriptome constitutes an uncharacterized level of regulation of post-transcriptional events in cancer. Here, we found that the stress-induced long non-coding RNA (lncRNA), LINCO2657 or LASTR (lncRNA associated with SART3 regulation of splicing), is upregulated in hypoxic breast cancer and is essential for the growth of LASTR-positive triple-negative breast tumors. LASTR is upregulated in several types of epithelial cancers due to the activation of the stress-induced JNK/c-JUN pathway. Using a mass-spectrometry based approach, we identified the RNA-splicing factor SART3 as a LASTR-interacting partner. We found that LASTR promotes splicing efficiency by controlling SART3 association with the U4 and U6 small nuclear ribonucleoproteins (snRNP) during spliceosome recycling. Intron retention induced by LASTR depletion downregulates expression of essential genes, ultimately decreasing the fitness of cancer cells

Alteracije onkogena c-myc i c-erbB-2 u malignim tumorima jajnika

Introduction. According to clinical and epidemiological studies, ovarian cancer ranks fifth in cancer deaths among women. The causes of ovarian cancer remain largely unknown but various factors may increase the risk of developing it, such as age, family history of cancer, childbearing status etc. This cancer results from a succession of genetic alterations involving oncogenes and tumour suppressor genes, which have a critical role in normal cell growth regulation. Mutations and/or overexpression of three oncogenes, c-erbB-2, c-Myc and K-ras, and of the tumour suppressor gene p53, have been frequently observed in a sporadic ovarian cancer. Objective. The aim of the present study was to analyze c-Myc and c-erbB-2 oncogene alterations, specifically amplification, as one of main mechanisms of their activation in ovarian cancers and to establish a possible association with the pathogenic process. Methods. DNA was isolated from 15 samples of malignant and 5 benign ovarian tumours, using proteinase K digestion, followed by phenol-chloroform isoamyl extraction and ethanol precipitation. C-Myc and c-erbB-2 amplification were detected by differential PCR. The level of gene copy increase was measured using the Scion image software. Results. The amplification of both c-Myc and c-erbB-2 was detected in 26.7% of ovarian epithelial carcinoma specimens. Only one tumour specimen concomitantly showed increased gene copy number for both studied genes. Interestingly, besides amplification, gene deletion was also detected (26.7% for c-erbB-2). Most of the ovarian carcinomas with alterations in c-Myc and c-erbB-2 belonged to advanced FIGO stages. Conclusion. The amplification of c-Myc and c-erbB-2 oncogenes in ovarian epithelial carcinomas is most probably a late event in the pathogenesis conferring these tumours a more aggressive biological behaviour. Similarly, gene deletions point to genomic instability in epithelial carcinomas in higher clinical stages as the result of clonal evolution and selection.Uvod. Kliničke i epidemiološke studije su pokazale da je kancer jajnika peti po redu uzročnik smrti žena. Iako postoje mnogi predisponirajući faktori, kao što su starosna dob, porodična istorija kancera, sterilnost, broj rođene dece i dr., tačni uzroci nastanka tumora jajnika još nisu poznati. Zna se, međutim, da je kancer jajnika rezultat akumulacije različitih genskih alteracija, od kojih su najznačajnije mutacije, odnosno povišena ekspresija određenih onkogena, kao što su c-myc, c-erbB-2 i K-ras, i tumor-supresorskih gena, od kojih je najvažniji p53. Cilj rada. Cilj istraživanja je bio da se ispitaju alteracije c-myc i c-erbB-2 (pre svega njihove amplifikacije), najčešćeg mehanizma aktivacije ovih onkogena, u epitelnim karcinomima jajnika, i utvrde njihove potencijalne uloge u patogenezi ovog tipa neoplazmi u našoj populaciji. Metode rada. DNK je izolovana iz 15 uzoraka malignih tumora i pet uzoraka benignih tumora jajnika. Amplifikacije onkogena c-myc i c-erbB-2 ustanovljavane su metodom diferencijalne reakcije lančanog umnožavanja DNK (engl. differential polymerase chain reaction - dPCR). Nivo amplifikacije određen je nakon denzitometrijskog merenja traka na gelu primenom programa Scion image. Rezultati. Amplifikacija i gena c-myc i c-erbB-2 otkrivena je u četiri uzorka (26,7%) epitelnog karcinoma jajnika. Jedan od ispitivanih uzoraka je imao simultanu amplifikaciju oba gena. Većina uzoraka bila je visokog stadijuma prema kriterijumima Međunarodne federacije za ginekologiju i akušerstvo (International Federation of Gynecology and Obstetrics - FIGO). Zanimljivo je da je pored amplifikacije nezavisno ustanovljena i delecija gena c-erbB-2 u 26,7% karcinoma. Svi karcinomi sa delecijama su takođe pripadali visokim kliničkim stadijumima. Zaključak. Amplifikovani onkogeni c-myc i c-erbB-2 su odlika kasnih stadijuma epitelnih maligniteta i verovatno jedan od razloga njihovog agresivnog biološkog ponašanja. Slično tome, i delecija gena erb obeležava uznapredovale stadijume bolesti i ukazuje na genomsku nestabilnost koja se javlja u epitelnim karcinomima kao rezultat evolucije i selekcije različitih tumorskih klonova

Interaction of hnRNPA1/A2 and DAZAP1 with an Alu-Derived Intronic Splicing Enhancer Regulates ATM Aberrant Splicing

We have previously identified an Alu-derived Intronic Splicing enhancer (ISE) in the Ataxia Teleangectasia Mutated gene (ATM) that facilitates intron pre-mRNA processing and leads to the inclusion of a cryptic exon in the final mRNA transcript. By using an RNA pull-down assay, we show here that hnRNPA1/A2, HuR and DAZAP1 splicing factors and DHX36 RNA helicase bind to the ISE. By functional studies (overexpression and siRNA experiments), we demonstrate that hnRNPA1 and DAZAP1 are indeed involved in ISE-dependent ATM cryptic exon activation, with hnRNPA1 acting negatively and DAZAP1 positively on splicing selection. On the contrary, HuR and DHX36 have no effect on ATM splicing pattern. These data suggest that splicing factors with both negative and positive effect can assemble on the intronic Alu repeats and regulate pre-mRNA splicing

An Alu-derived intronic splicing enhancer facilitates intronic processing and modulates aberrant splicing in ATM

We have previously reported a natural GTAA deletion within an intronic splicing processing element (ISPE) of the ataxia telangiectasia mutated (ATM) gene that disrupts a non-canonical U1 snRNP interaction and activates the excision of the upstream portion of the intron. The resulting pre-mRNA splicing intermediate is then processed to a cryptic exon, whose aberrant inclusion in the final mRNA is responsible for ataxia telangiectasia. We show here that the last 40 bases of a downstream intronic antisense Alu repeat are required for the activation of the cryptic exon by the ISPE deletion. Evaluation of the pre-mRNA splicing intermediate by a hybrid minigene assay indicates that the identified intronic splicing enhancer represents a novel class of enhancers that facilitates processing of splicing intermediates possibly by recruiting U1 snRNP to defective donor sites. In the absence of this element, the splicing intermediate accumulates and is not further processed to generate the cryptic exon. Our results indicate that Alu-derived sequences can provide intronic splicing regulatory elements that facilitate pre-mRNA processing and potentially affect the severity of disease-causing splicing mutations

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements