Biology subjects

Durley, S. C.

Publications and source records attributed to Durley, S. C..

3 recordsLinked to original sources

bioRxiv2021

R-loop-induced p21 expression following CDC73, CTR9, and PAF1 loss protects cancer cells against replicative catastrophe following WEE1 inhibition

WEE1 inhibitors have now advanced into clinical studies as monotherapy or in combination with chemoradiotherapy in TP53, RAS, BRAF, and SETD2 mutation carriers across several tumour types, yet mechanisms of resistance are still poorly understood. Here, we further elucidate the mechanisms by which AZD1775, the most potent WEE1 inhibitor, kills cells and reveal additional genetic interactions that can result in resistance, but could be used to optimise its clinical utility. We identified RNA Polymerase II-associated factor 1 (PAF1) complex members, CDC73, CTR9, and PAF1 as major determinants of WEE1-inhibitor sensitivity in isogenic SETD2-positive and negative cell lines. PAF1-knockdown cells resist higher doses of the WEE1 inhibitor, which we show is due to reduced DNA damage induction ({gamma}H2AX) and delayed G1 checkpoint activation, ultimately protecting cells against replicative catastrophe. Investigations into the molecular mechanisms responsible for PAF1-mediated resistance identify involvement of R-loops and subsequent activation of the cyclin-dependent kinase inhibitor p21Cip1/Waf1, which in addition to causing prolonged G1 arrest in the following cell cycle, also regulates CDK activity, therefore limiting replication. These results provide evidence that the PAF1 complex and p21 are important regulators of proliferation under increased DNA replication stress and their expression levels might be useful biomarkers to predict clinical response to WEE1 inhibitors and other ribonucleotide reductase inhibitors.

cancer biology↗

bioRxiv2020

Persistent broken chromosome inheritance drives genome instability

Persistent DNA damage arising from unrepaired broken chromosomes or telomere loss can promote DNA damage checkpoint adaptation, and cell cycle progression, thereby increasing cell survival but also genome instability. However, the nature and extent of such instability is unclear. We show, using Schizosaccharomyces pombe, that inherited broken chromosomes, arising from failed homologous recombination repair, are subject to cycles of segregation, DNA replication and extensive end-processing, termed here SERPent cycles, by daughter cells, over multiple generations. Following Chk1 loss these post-adaptive cycles continue until extensive processing through inverted repeats promotes annealing, fold-back inversion and a spectrum of chromosomal rearrangements, typically isochromosomes, or chromosome loss, in the resultant population. These findings explain how persistent DNA damage drives widespread genome instability, with implications for punctuated evolution, genetic disease and tumorigenesis. One Sentence SummaryReplication and processing of inherited broken chromosomes drives chromosomal instability.

molecular biology↗

bioRxiv2018

An essential role for dNTP homeostasis following CDK-induced replication stress

Replication stress is a common feature of cancer cells, and thus a potentially important therapeutic target. Here we show that CDK-induced replication stress is synthetic lethal with mutations disrupting dNTP homeostasis in fission yeast. Wee1 inactivation leads to increased dNTP demand and replication stress through CDK-induced firing of dormant replication origins. Subsequent dNTP depletion leads to inefficient DNA replication, Mus81-dependent DNA damage, and to genome instability. Cells respond to this replication stress by increasing dNTP supply through Set2-dependent MBF-induced expression of Cdc22, the catalytic subunit of ribonucleotide reductase (RNR). Disrupting dNTP synthesis following Wee1 inactivation, through abrogating Set2-dependent H3K36 tri-methylation or DNA integrity checkpoint inactivation results in critically low dNTP levels, replication collapse and cell death, which can be rescued by increasing dNTP levels. These findings support a dNTP supply and demand model in which maintaining dNTP homeostasis is essential to prevent replication catastrophe in response to CDK-induced replication stress.

molecular biology↗