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Recent research shows that extra-nuclear cell-free chromatin (cfCh) released from dying cells can freely enter into healthy cells and integrate into their genomes. Genomic integration of cfCh leads to dsDNA breaks and activation of inflammatory cytokines both of which occur concurrently with similar kinetics and that induction of inflammation can be abrogated by preventing DNA breaks with the use of cfCh inactivating agents. The proposal is put forward that inflammatory cytokines are a new family of DDR proteins that are activated following dsDNA breaks inflicted by genomic integration of cfCh.

The cellular response to DNA damage (DDR) that causes replication collapse and/or DNA double strand breaks, is characterised by a massive change in the post-translational modifications (PTM) of hundreds of proteins involved in the detection and repair of DNA damage, and the communication of the state of damage to the cellular systems that regulate replication and cell division. A substantial proportion of these PTMs involve targeted phosphorylation, which among other effects, promotes the formation of multiprotein complexes through the specific binding of phosphorylated motifs on one protein, by specialised domains on other proteins. Understanding the nature of these phosphorylation mediated interactions allows definition of the pathways and networks that coordinate the DDR, and helps identify new targets for therapeutic intervention that may be of benefit in the treatment of cancer, where DDR plays a key role. In this review we summarise the present understanding of how phosphorylated motifs are recognised by BRCT domains, which occur in many DDR proteins. We particularly focus on TOPBP1 – a multi-BRCT domain scaffold protein with essential roles in replication and the repair and signalling of DNA damage.

The DNA damage response (DDR) is a series of pathways and processes required to repair lesions to DNA. These pathways range from repairing strand breaks to the double helix, damaged bases formed after oxidation or deamination, inaccurate DNA replication resulting in mispaired base alignment, intrastrand crosslinks that trigger cell death, and a plethora of other genomic insults. The DDR is believed to be a critical component of radio and chemoresistance in many cancers as well, with the tumor's ability to repair therapy induced damage being an important tool used to survive traditional chemotherapeutic agents. Here we summarize advances made in specifically targeting DDR proteins in cancer therapy and project on the potential breakthroughs and pitfalls to arise as the field progresses.

Genome integrity is constantly monitored by sophisticated cellular networks, collectively termed the DNA damage response (DDR). A common feature of DDR proteins is their mobilization in response to genotoxic stress. Here, we outline how the development of various complementary methodologies has provided valuable insights into the spatiotemporal dynamics of DDR protein assembly/disassembly at sites of DNA strand breaks in eukaryotic cells. Considerable advances have also been made in understanding the underlying molecular mechanisms for these events, with post-translational modifications of DDR factors being shown to play prominent roles in controlling the formation of foci in response to DNA-damaging agents. We review these regulatory mechanisms and discuss their biological significance to the DDR.

The DNA damage response (DDR) is essential for maintaining the genomic integrity of the cell, and its disruption is one of the hallmarks of cancer. Classically, defects in the DDR have been exploited therapeutically in the treatment of cancer with radiation therapies or genotoxic chemotherapies. More recently, protein components of the DDR systems have been identified as promising avenues for targeted cancer therapeutics. Here, we present an in-depth analysis of the function, role in cancer and therapeutic potential of 450 expert-curated human DDR genes. We discuss the DDR drugs that have been approved by the US Food and Drug Administration (FDA) or that are under clinical investigation. We examine large-scale genomic and expression data for 15 cancers to identify deregulated components of the DDR, and we apply systematic computational analysis to identify DDR proteins that are amenable to modulation by small molecules, highlighting potential novel therapeutic targets.

CI1.02-2.55), DMFS (HR1.60, 95%CI1.02-2.52), but notOS (HR1.46, 95% CI 0.92-2.31). Greater age and number of positive pN2 nodes were also independent predictors of LRF, DMFS, and OS. Conclusions: DDR proteins correlate with radiation resistance in NSCLC cell lines, and UPF1 KD downregulates these DDR genes in concert. While UPF1 levels in tumors do not itself correlate with disease outcomes in patients, downregulating its levels may reduce RAD50 whose expression is prognostic in patients. UPF1 could serve as an attractive target to enhance radiation sensitization in NSCLC. Author Disclosure: S.H. Lin: None. J. Gudikote: None. U. Giri: None. J. Fujimoto: None. J. Wang: None. C. Wei: None. H. Chen: None. B. Farnia: None. D.R. Gomez: None. M.D. Story: None. R.U. Komaki: None. S.G. Swisher: None. I. Wistuba: None. J.V. Heymach: None.

Epstein-Barr virus (EBV), a type of oncogenic herpesvirus, is associated with human malignancies. Previous studies have shown that reactivation of EBV in infected cells induces ATM-dependent DNA damage response (DDR). The functional role and involvement of ATM activation during lytic induction remains obscure. In this study, the essential role of ATM for viral DNA replication was examined in EBV-infected nasopharyngeal epithelial cells. Induction of lytic EBV infection triggers ATM activation and localization of DDR proteins at the viral replication compartments. Suppression of ATM activity using siRNA approach or specific chemical inhibitor diminished EBV DNA replication and production of infectious virion in EBV-infected cells induced to undergo lytic infection. Phosphorylation of Sp1 is a downstream event of ATM activation. The phosphorylation of Sp1 at serine 101 residue is crucial in promoting the accretion of EBV replication proteins at the replication compartment to facilitate viral DNA replication. Depletion of Sp1 suppresses viral DNA replication and localization of EBV replication proteins to the replication compartments. Our studies support an important role of ATM activation in lytic infection of EBV. Phosphorylation of Sp1 is an essential process mediating the recruitment of EBV replication protein to replication compartments. Our study highlights the importance of DDR pathway in lytic infection of EBV and suggests the potential application of specific DDR inhibitors to control the EBV replication in infected cells. Funding support: Research Grant Council of Hong Kong (GRF #779312 & 779713; AoE/M-06/08). Note: This abstract was not presented at the meeting. Citation Format: George Sai-Wah Tsao, Pok Man Hau. The role of ATM in lytic infection of EBV in nasopharyngeal epithelial cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2392. doi:10.1158/1538-7445.AM2014-2392