scholarly journals Conserved roles of RECQ-like helicases Sgs1 and BLM in preventing R-loop associated genome instability

2017 ◽  
Author(s):  
Carolina A. Novoa ◽  
Emily Yun-Chia Chang ◽  
Maria J. Aristizabal ◽  
Yan Coulombe ◽  
Romulo Segovia ◽  
...  
Keyword(s):  
Genome Instability ◽  
Human Cancer ◽  
Wide Distribution ◽  
Dna Helicase ◽  
Human Cancer Cells ◽  
Genome Wide ◽  
Blm Helicase ◽  
Dna Replication And Repair ◽  
Copy Number Changes

AbstractSgs1 is a yeast DNA helicase functioning in DNA replication and repair, and is the orthologue of the human Bloom’s syndrome helicase BLM. Here we analyze the mutation signature associated with SGS1 deletion in yeast, and find frequent copy number changes flanked by regions of repetitive sequence and high R-loop forming potential. We show that loss of SGS1 increases R-loop accumulation and sensitizes cells to replication-transcription collisions. Accordingly, in sgs1Δ cells the genome-wide distribution of R-loops shifts to known sites of Sgs1 action, replication pausing regions, and to long genes. Depletion of the orthologous BLM helicase from human cancer cells also increases R-loop levels, and R-loop-associated genome instability. In support of a direct effect, BLM is found physically proximal to DNA:RNA hybrids in human cells, and can efficiently unwind R-loops in vitro. Together our data describe a conserved role for Sgs1/BLM in R-loop suppression and support an increasingly broad view of DNA repair and replication fork stabilizing proteins as modulators of R-loop mediated genome instability.

scholarly journals RECQ-like helicases Sgs1 and BLM regulate R-loop–associated genome instability

2017 ◽  
Vol 216 (12) ◽  
pp. 3991-4005 ◽  
Author(s):  
Emily Yun-Chia Chang ◽  
Carolina A. Novoa ◽  
Maria J. Aristizabal ◽  
Yan Coulombe ◽  
Romulo Segovia ◽  
...  
Keyword(s):  
Genome Instability ◽  
Human Cancer ◽  
Dna Helicase ◽  
Bloom's Syndrome ◽  
Human Cancer Cells ◽  
Bloom’S Syndrome ◽  
Dna Replication And Repair ◽  
Copy Number Changes ◽  
Long Genes

Sgs1, the orthologue of human Bloom’s syndrome helicase BLM, is a yeast DNA helicase functioning in DNA replication and repair. We show that SGS1 loss increases R-loop accumulation and sensitizes cells to transcription–replication collisions. Yeast lacking SGS1 accumulate R-loops and γ-H2A at sites of Sgs1 binding, replication pausing regions, and long genes. The mutation signature of sgs1Δ reveals copy number changes flanked by repetitive regions with high R-loop–forming potential. Analysis of BLM in Bloom’s syndrome fibroblasts or by depletion of BLM from human cancer cells confirms a role for Sgs1/BLM in suppressing R-loop–associated genome instability across species. In support of a potential direct effect, BLM is found physically proximal to DNA:RNA hybrids in human cells, and can efficiently unwind R-loops in vitro. Together, our data describe a conserved role for Sgs1/BLM in R-loop suppression and support an increasingly broad view of DNA repair and replication fork stabilizing proteins as modulators of R-loop–mediated genome instability.

scholarly journals DNA damage and genome instability by G-quadruplex ligands are mediated by R loops in human cancer cells

2018 ◽  
Vol 116 (3) ◽  
pp. 816-825 ◽  
Author(s):  
Alessio De Magis ◽  
Stefano G. Manzo ◽  
Marco Russo ◽  
Jessica Marinello ◽  
Rita Morigi ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cancer Cells ◽  
Genome Instability ◽  
Human Cancer ◽  
Cell Killing ◽  
Dna Structures ◽  
Human Cancer Cells ◽  
Cellular Effects ◽  
Genome Wide ◽  
G Quadruplex

G quadruplexes (G4s) and R loops are noncanonical DNA structures that can regulate basic nuclear processes and trigger DNA damage, genome instability, and cell killing. By different technical approaches, we here establish that specific G4 ligands stabilize G4s and simultaneously increase R-loop levels within minutes in human cancer cells. Genome-wide mapping of R loops showed that the studied G4 ligands likely cause the spreading of R loops to adjacent regions containing G4 structures, preferentially at 3′-end regions of expressed genes, which are partially ligand-specific. Overexpression of an exogenous human RNaseH1 rescued DNA damage induced by G4 ligands in BRCA2-proficient and BRCA2-silenced cancer cells. Moreover, even if the studied G4 ligands increased noncanonical DNA structures at similar levels in nuclear chromatin, their cellular effects were different in relation to cell-killing activity and stimulation of micronuclei, a hallmark of genome instability. Our findings therefore establish that G4 ligands can induce DNA damage by an R loop-dependent mechanism that can eventually lead to different cellular consequences depending on the chemical nature of the ligands.

Structure-Reactivity Relationships on Substrates and Inhibitors of the Lysine Deacylase Sirtuin 2 from Schistosoma Mansoni (SmSirt2)

2019 ◽  
Author(s):  
Daria Monaldi ◽  
Dante Rotili ◽  
Julien Lancelot ◽  
Martin Marek ◽  
Nathalie Wössner ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Human Cancer ◽  
Egg Laying ◽  
Human Cancer Cells ◽  
Parasite Survival ◽  
Survival And Reproduction ◽  
Emergence Of Resistance ◽  
First Time ◽  
Parasitic Life Cycle

The only drug for treatment of Schistosomiasis is Praziquantel, and the possible emergence of resistance makes research on novel therapeutic agents necessary. Targeting of Schistosoma mansoni epigenetic enzymes, which regulate the parasitic life cycle, emerged as promising approach. Due to the strong effects of human Sirtuin inhibitors on parasite survival and reproduction, Schistosoma sirtuins were postulated as therapeutic targets. In vitro testing of synthetic substrates of S. mansoni Sirtuin 2 (SmSirt2) and kinetic experiments on a myristoylated peptide demonstrated lysine long chain deacylation as an intrinsic SmSirt2 activity for the first time. Focused in vitro screening of the GSK Kinetobox library and structure-activity relationships (SAR) of identified hits, led to the first SmSirt2 inhibitors with activity in the low micromolar range. Several SmSirt2 inhibitors showed potency against both larval schistosomes (viability) and adult worms (pairing, egg laying) in culture without general toxicity to human cancer cells.<br>

scholarly journals A New Smoothened Antagonist Bearing the Purine Scaffold Shows Antitumour Activity In Vitro and In Vivo

2021 ◽  
Vol 22 (16) ◽  
pp. 8372
Author(s):  
Ana María Zárate ◽  
Christian Espinosa-Bustos ◽  
Simón Guerrero ◽  
Angélica Fierro ◽  
Felipe Oyarzún-Ampuero ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Human Cancer ◽  
Antitumour Activity ◽  
Anticancer Compounds ◽  
Human Cancer Cells ◽  
Cycle Arrest ◽  
Apoptosis Inducer ◽  
Purine Ring

The Smoothened (SMO) receptor is the most druggable target in the Hedgehog (HH) pathway for anticancer compounds. However, SMO antagonists such as vismodegib rapidly develop drug resistance. In this study, new SMO antagonists having the versatile purine ring as a scaffold were designed, synthesised, and biologically tested to provide an insight to their mechanism of action. Compound 4s was the most active and the best inhibitor of cell growth and selectively cytotoxic to cancer cells. 4s induced cell cycle arrest, apoptosis, a reduction in colony formation and downregulation of PTCH and GLI1 expression. BODIPY-cyclopamine displacement assays confirmed 4s is a SMO antagonist. In vivo, 4s strongly inhibited tumour relapse and metastasis of melanoma cells in mice. In vitro, 4s was more efficient than vismodegib to induce apoptosis in human cancer cells and that might be attributed to its dual ability to function as a SMO antagonist and apoptosis inducer.

Rhodium(i) N-heterocyclic carbene complexes: synthesis and cytotoxic properties

2021 ◽  
Vol 45 (11) ◽  
pp. 5176-5183
Author(s):  
Ichraf Slimani ◽  
Serap Şahin-Bölükbaşı ◽  
Mustafa Ulu ◽  
Enes Evren ◽  
Nevin Gürbüz ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Mtt Assay ◽  
Incubation Time ◽  
Human Cancer ◽  
Cytotoxic Activities ◽  
Carbene Complexes ◽  
Human Cancer Cells ◽  
Benzimidazolium Salts ◽  
Ht 29

A series of benzimidazolium salts and their [RhCl(NHC)(COD)] complexes were synthesized. All compounds were screened for in vitro cytotoxic activities against a panel of human cancer cells (HT-29 colon, Ishikawa endometrial, U-87 glioblastoma) using the MTT assay for 48 h incubation time.

PLATELET ACTIVATION BY HUMAN CANCER CELLS GROWN “IN VITRO” OR DISSOCIATED FROM TUMOUR TISSUES

1987 ◽  
Author(s):  
G Grignani ◽  
L Pacchiarini ◽  
M Zucchella ◽  
L Dezza ◽  
S C Rizzo
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Human Cancer ◽  
Iodoacetic Acid ◽  
Tumour Cells ◽  
Human Cancer Cells ◽  
Human Tumour Cells ◽  
Dissociated Cells ◽  
Lymphoblastic Cells

The mechanisms of platelet activation by human tumour cells grown “in vitro” or freshly dissociated from tumour tissues have been investigated.MoCCL human T-lymphoblastic cells cultured “in vitro” induced platelet aggregation through the production of ADP, as evidenced by inhibition of the effect by apyrase. The maximum of ADP production by tumour cells was reached after 1 hour and was 225 p moles/106 cells.On the contrary, platelet aggregation induced by 5637 human bladder carcinoma cells was not inhibited by apyrase, but was abolished by hirudin, indicating the important role of thrombin in this effect.Tumour cells dissociated from 3 breast carcinomas showed a very high platelet aggregating activity, which was not inhibited by hirudin or apyrase, but was abolished by iodoacetic acid, suggesting a role for a cystein-protease in platelet activation.These results confirm that platelets can be activated by tumour cells through different mechanisms; they also suggest that the methods employed to obtain the tumour cells can influence the results, probably because of the different cell populations which are present in the dissociated tumour tissues.Informations obtained with freshly dissociated cells are interesting, because this method has been used seldom so far and because it provides a more physiological approach to the study of the interactions of tumours and platelets.

scholarly journals Monohydrazone Based G-Quadruplex Selective Ligands Induce DNA Damage and Genome Instability in Human Cancer Cells

2020 ◽  
Vol 63 (6) ◽  
pp. 3090-3103 ◽  
Author(s):  
Jussara Amato ◽  
Giulia Miglietta ◽  
Rita Morigi ◽  
Nunzia Iaccarino ◽  
Alessandra Locatelli ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cancer Cells ◽  
Genome Instability ◽  
Human Cancer ◽  
Human Cancer Cells ◽  
G Quadruplex ◽  
Selective Ligands

scholarly journals Study of the antiproliferative potential of seed extracts from Northeastern Brazilian plants

2011 ◽  
Vol 83 (3) ◽  
pp. 1045-1058 ◽  
Author(s):  
Paulo Michel P. Ferreira ◽  
Davi F. Farias ◽  
Martônio P. Viana ◽  
Terezinha M. Souza ◽  
Ilka M. Vasconcelos ◽  
...  
Keyword(s):  
Human Cancer ◽  
Ethanolic Extract ◽  
Cell Number ◽  
Northeastern Brazil ◽  
Human Cancer Cells ◽  
Ic50 Value ◽  
Underlying Mechanisms ◽  
Apoptotic Pathways ◽  
Seed Extracts

This study assessed the antiproliferative and cytotoxic potential against tumor lines of ethanolic seed extracts of 21 plant species belonging to different families from Northeastern Brazil. In addition, some underlying mechanisms involved in this cytotoxicity were also investigated. Among the 21 extracts tested, the MTT assay after 72 h of incubation demonstrated that only the ethanolic extract obtained from Myracrodruon urundeuva seeds (EEMUS), which has steroids, alkaloids and phenols, showed in vitro cytotoxic activity against human cancer cells, being 2-fold more active on leukemia HL-60 line [IC50 value of 12.5 (9.5-16.7) μg/mL] than on glioblastoma SF-295 [IC50 of 25.1 (17.3-36.3) μg/mL] and Sarcoma 180 cells [IC50 of 38.1 (33.5-43.4) μg/mL]. After 72h exposure, flow cytometric and morphological analyses of HL-60-treated cells showed that EEMUS caused decrease in cell number, volume and viability as well as internucleosomal DNA fragmentation in a dose-dependent way, suggesting that the EEMUS triggers apoptotic pathways of cell death.

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