Comparative study of DNA damage, cell cycle and apoptosis in human K562 and CCRF-CEM leukemia cells: Role of BCR/ABL in therapeutic resistance

Abstract Background The early molecular events in human thyrocytes after 131I exposure have not yet been unravelled. Therefore, we investigated the role of TSH in the 131I-induced DNA damage response and gene expression in primary cultured human thyrocytes. Methods Following exposure of thyrocytes, in the presence or absence of TSH, to 131I (β radiation), γ radiation (3 Gy), and hydrogen peroxide (H2O2), we assessed DNA damage, proliferation, and cell-cycle status. We conducted RNA sequencing to profile gene expression after each type of exposure and evaluated the influence of TSH on each transcriptomic response. Results Overall, the thyrocyte responses following exposure to β or γ radiation and to H2O2 were similar. However, TSH increased 131I-induced DNA damage, an effect partially diminished after iodide uptake inhibition. Specifically, TSH increased the number of DNA double-strand breaks in nonexposed thyrocytes and thus predisposed them to greater damage following 131I exposure. This effect most likely occurred via Gα q cascade and a rise in intracellular reactive oxygen species (ROS) levels. β and γ radiation prolonged thyroid cell-cycle arrest to a similar extent without sign of apoptosis. The gene expression profiles of thyrocytes exposed to β/γ radiation or H2O2 were overlapping. Modulations in genes involved in inflammatory response, apoptosis, and proliferation were observed. TSH increased the number and intensity of modulation of differentially expressed genes after 131I exposure. Conclusions TSH specifically increased 131I-induced DNA damage probably via a rise in ROS levels and produced a more prominent transcriptomic response after exposure to 131I.

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Trp53 ablation fails to prevent microcephaly in mouse pallium with impaired minor intron splicing

10.1101/2021.03.05.434172 ◽

2021 ◽

Author(s):

Alisa K. White ◽

Marybeth Baumgartner ◽

Madisen F. Lee ◽

Kyle D. Drake ◽

Gabriela S. Aquino ◽

...

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Intron Retention ◽

Conditional Knockout ◽

Intron Splicing ◽

Small Nuclear Rna ◽

Primary Microcephaly ◽

Double Knockout ◽

Nuclear Rna

AbstractMutations in minor spliceosome component RNU4ATAC, a small nuclear RNA (snRNA), are linked to primary microcephaly. We have reported that in the conditional knockout (cKO) mice for Rnu11, another minor spliceosome snRNA, minor intron splicing defect in minor intron-containing genes (MIGs) regulating cell cycle resulted in cell cycle defects, with a concomitant increase in γH2aX+ cells and p53-mediated apoptosis. Trp53 ablation in the Rnu11 cKO mice did not prevent microcephaly. However, RNAseq analysis of the double knockout (dKO) pallium reflected transcriptomic shift towards the control from the Rnu11 cKO. We found elevated minor intron retention and alternative splicing across minor introns in the dKO. Disruption of these MIGs resulted in cell cycle defects that were more severe and detected earlier in the dKO, but with delayed detection of γH2aX+ DNA damage. Thus, p53 might also play a role in causing DNA damage in the developing pallium. In all, our findings further refine our understanding of the role of the minor spliceosome in cortical development and identify MIGs underpinning microcephaly in minor spliceosome-related diseases.

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Genomic hallmarks of cellular dormancy in cancer and therapeutic implications

10.21203/rs.3.rs-1104031/v1 ◽

2021 ◽

Author(s):

Maria Secrier ◽

Anna Wiecek ◽

Stephen Cutty ◽

Daniel Kornai ◽

Mario Parreno-Centeno ◽

...

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Therapy Resistance ◽

Therapeutic Resistance ◽

Epigenetic Mechanisms ◽

Therapeutic Implications ◽

Damage Repair ◽

Repair Deficiency ◽

Cell Data ◽

Cell Cycle Kinase

Abstract Therapy resistance in cancer is often driven by a subpopulation of cells that are temporarily arrested in a non-proliferative, quiescent or ‘dormant’ state, which is difficult to capture and whose mutational drivers remain largely unknown. We developed methodology to uniquely identify this state from transcriptomic signals and characterised its prevalence and genomic constraints in solid primary tumours. We show dormancy preferentially emerges in the context of more stable, less mutated genomes which maintain TP53 integrity and lack the hallmarks of DNA damage repair deficiency, while presenting increased APOBEC mutagenesis. We uncover novel genomic dependencies of this process, including the amplification of the centrosomal gene CEP89 as a driver of dormancy impairment. Lastly, we demonstrate that dormancy underlies unfavourable responses to various therapies exploiting cell cycle, kinase signalling and epigenetic mechanisms in single cell data, and propose a signature of dormancy-linked therapeutic resistance to further study and clinically track this state.

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