Chemotherapy-induced COX-2 upregulation by cancer cells defines their inflammatory properties and limits the efficacy of chemoimmunotherapy combinations.

Cytotoxic therapies, besides directly inducing cancer cell death, can stimulate immune-dependent tumor growth control or paradoxically accelerate tumor progression. The underlying mechanisms dictating these opposing outcomes are poorly defined. Here, we show that cytotoxic therapy acutely upregulates cyclooxygenase (COX)-2 expression and prostaglandin E (PGE) production in cancer cells with pre-existing COX-2 activity.

Anti-Inflammatory Drugs Remodel the Tumor Immune Environment to Enhance Immune Checkpoint Blockade Efficacy.

Identifying strategies to improve the efficacy of immune checkpoint blockade (ICB) remains a major clinical need. Here, we show that therapeutically targeting the COX2/PGE/EP2-4 pathway with widely used nonsteroidal and steroidal anti-inflammatory drugs synergized with ICB in mouse cancer models. We exploited a bilateral surgery model to distinguish responders from nonresponders shortly after treatment and identified acute IFNγ-driven transcriptional remodeling in responder mice, which was also associated with patient benefit to ICB.

TEX264 coordinates p97- and SPRTN-mediated resolution of topoisomerase 1-DNA adducts.

Eukaryotic topoisomerase 1 (TOP1) regulates DNA topology to ensure efficient DNA replication and transcription. TOP1 is also a major driver of endogenous genome instability, particularly when its catalytic intermediate-a covalent TOP1-DNA adduct known as a TOP1 cleavage complex (TOP1cc)-is stabilised. TOP1ccs are highly cytotoxic and a failure to resolve them underlies the pathology of neurological disorders but is also exploited in cancer therapy where TOP1ccs are the target of widely used frontline anti-cancer drugs.

Study of the mechanisms of crocetin-induced differentiation and apoptosis in human acute promyelocytic leukemia cells.

Crocetin, the major carotenoid in saffron, exhibits potent anticancer effects. However, the antileukemic effects of crocetin are still unclear, especially in primary acute promyelocytic leukemia (APL) cells. In the current study, the potential antipromyelocytic leukemia activity of crocetin and the underlying molecular mechanisms were investigated.

UVA-induced carbon-centred radicals in lightly pigmented cells detected using ESR spectroscopy.

Ultraviolet-A and melanin are implicated in melanoma, but whether melanin in vivo screens or acts as a UVA photosensitiser is debated. Here, we investigate the effect of UVA-irradiation on non-pigmented, lightly and darkly pigmented melanocytes and melanoma cells using electron spin resonance (ESR) spectroscopy. Using the spin trap 5,5 Dimethyl-1-pyrroline N-oxide (DMPO), carbon adducts were detected in all cells.

UCHL3 Regulates Topoisomerase-Induced Chromosomal Break Repair by Controlling TDP1 Proteostasis.

Genomic damage can feature DNA-protein crosslinks whereby their acute accumulation is utilized to treat cancer and progressive accumulation causes neurodegeneration. This is typified by tyrosyl DNA phosphodiesterase 1 (TDP1), which repairs topoisomerase-mediated chromosomal breaks. Although TDP1 levels vary in multiple clinical settings, the mechanism underpinning this variation is unknown.

Studying TDP1 Function in DNA Repair.

Topoisomerase poisons act by inducing abortive topoisomerase reactions, which generate stable protein-DNA breaks (PDBs) that interfere with transcription elongation and progression of replication forks. In vertebrates, Tyrosyl-DNA phosphodiesterase 1 (TDP1) plays a major role in removal of topoisomerase 1-associated PDBs in the nucleus and mitochondria by hydrolyzing the 3'-phosphotyrosine bond. Depletion of TDP1 sensitizes tumor cells with defective DNA repair capacity to the genotoxic effect of TOP1 poisons, while homozygous mutation of the catalytic residue of TDP1 is associated with cerebellar degeneration and ataxia.

C9orf72 expansion disrupts ATM-mediated chromosomal break repair.

Hexanucleotide repeat expansions represent the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia, though the mechanisms by which such expansions cause neurodegeneration are poorly understood. We report elevated levels of DNA-RNA hybrids (R-loops) and double strand breaks in rat neurons, human cells and C9orf72 ALS patient spinal cord tissues. Accumulation of endogenous DNA damage is concomitant with defective ATM-mediated DNA repair signaling and accumulation of protein-linked DNA breaks.

Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage.

Breakage of one strand of DNA is the most common form of DNA damage. Most damaged DNA termini require end-processing in preparation for ligation. The importance of this step is highlighted by the association of defects in the 3'-end processing enzyme tyrosyl DNA phosphodiesterase 1 (TDP1) and neurodegeneration and by the cytotoxic induction of protein-linked DNA breaks (PDBs) and oxidized nucleic acid intermediates during chemotherapy and radiotherapy.

A Comprehensive Analysis of the Dynamic Response to Aphidicolin-Mediated Replication Stress Uncovers Targets for ATM and ATMIN.

The cellular response to replication stress requires the DNA-damage-responsive kinase ATM and its cofactor ATMIN; however, the roles of this signaling pathway following replication stress are unclear. To identify the functions of ATM and ATMIN in response to replication stress, we utilized both transcriptomics and quantitative mass-spectrometry-based phosphoproteomics. We found that replication stress induced by aphidicolin triggered widespread changes in both gene expression and protein phosphorylation patterns.

Expression of a pathogenic mutation of SOD1 sensitizes aprataxin-deficient cells and mice to oxidative stress and triggers hallmarks of premature ageing.

Aprataxin (APTX) deficiency causes progressive cerebellar degeneration, ataxia and oculomotor apraxia in man. Cell free assays and crystal structure studies demonstrate a role for APTX in resolving 5'-adenylated nucleic acid breaks, however, APTX function in vertebrates remains unclear due to the lack of an appropriate model system. Here, we generated a murine model in which a pathogenic mutant of superoxide dismutase 1 (SOD1(G93A)) is expressed in an Aptx-/- mouse strain.

ATM deficiency results in accumulation of DNA-topoisomerase I covalent intermediates in neural cells.

Accumulation of peptide-linked DNA breaks contributes to neurodegeration in humans. This is typified by defects in tyrosyl DNA phosphodiesterase 1 (TDP1) and human hereditary ataxia. TDP1 primarily operates at single-strand breaks (SSBs) created by oxidative stress or by collision of transcription machinery with topoisomerase I intermediates (Top1-CCs).

SUMO modification of the neuroprotective protein TDP1 facilitates chromosomal single-strand break repair.

Breaking and sealing one strand of DNA is an inherent feature of chromosome metabolism to overcome torsional barriers. Failure to reseal broken DNA strands results in protein-linked DNA breaks, causing neurodegeneration in humans. This is typified by defects in tyrosyl DNA phosphodiesterase 1 (TDP1), which removes stalled topoisomerase 1 peptides from DNA termini.

Identification and characterisation of the BPI/LBP/PLUNC-like gene repertoire in chickens reveals the absence of a LBP gene.

Palate, lung and nasal epithelial clone (PLUNC) proteins are structural homologues to the innate defence molecules LPS-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI). PLUNCs make up the largest portion of the wider BPI/LBP/PLUNC-like protein family and are amongst the most rapidly evolving mammalian genes. In this study we systematically identified and characterised BPI/LBP/PLUNC-like protein-encoding genes in the chicken genome.

Mutations in Cullin 4B result in a human syndrome associated with increased camptothecin-induced topoisomerase I-dependent DNA breaks.

CUL4A and B encode subunits of E3-ubiquitin ligases implicated in diverse processes including nucleotide excision repair, regulating gene expression and controlling DNA replication fork licensing. But, the functional distinction between CUL4A and CUL4B, if any, is unclear. Recently, mutations in CUL4B were identified in humans associated with mental retardation, relative macrocephaly, tremor and a peripheral neuropathy.

TDP1 serine 81 promotes interaction with DNA ligase IIIalpha and facilitates cell survival following DNA damage.

Tyrosyl DNA phosphodiesterase (TDP1) is a DNA 3'-end processing enzyme that preferentially hydrolyses the bond between the 3'-end of DNA and stalled DNA topoisomerase 1. the importance of TDP1 is highlighted by its association with the human genetic disease spinocerebellar ataxia with axonal neuropathy. TDP1 comprises of a highly conserved C-terminus phosphodiesterase domain and a less conserved N-terminus tail.