Interfaces between cellular responses to DNA damage and cancer immunotherapy

Acquired resistance to PD-L1 inhibition enhances a type I IFN-regulated secretory program in tumors

Therapeutic inhibition of programmed cell death ligand (PD-L1) is linked to alterations in interferon (IFN) signaling. Since IFN-regulated intracellular signaling can control extracellular secretory programs in tumors to modulate immunity, we examined IFN-related secretory changes in tumor cells following resistance to PD-L1 inhibition. Here we report an anti-PD-L1 treatment-induced secretome (PTIS) in tumor models of acquired resistance that is regulated by type I IFNs. These secretory changes can suppress activation of T cells ex vivo while diminishing tumor cell cytotoxicity, revealing that tumor-intrinsic treatment adaptations can exert broad tumor-extrinsic effects. When reimplanted in vivo, resistant tumor growth can slow or stop when PTIS components are disrupted individually, or when type I IFN signaling machinery is blocked. Interestingly, genetic and therapeutic disruption of PD-L1 in vitro can only partially recapitulate the PTIS phenotype highlighting the importance of developing in vivo-based resistance models to more faithfully mimic clinically-relevant treatment failure. Together, this study shows acquired resistance to immune-checkpoint inhibitors 'rewires' tumor secretory programs controlled by type I IFNs that, in turn, can protect from immune cell attack.

CDC7 Inhibition Potentiates Antitumor Efficacy of PARP Inhibitor in Advanced Ovarian Cancer

Poly (ADP-ribose) Polymerase inhibitors (PARPi) have demonstrated remarkable clinical efficacy in treating ovarian cancer (OV) with BRCA1/2 mutations. However, drug resistance inevitably limits their clinical applications and there is an urgent need for improved therapeutic strategies to enhance the clinical utility of PARPi, such as Olaparib. Here, compelling evidence indicates that sensitivity of PARPi is associated with cell cycle dysfunction. Through high-throughput drug screening with a cell cycle kinase inhibitor library, XL413, a potent cell division cycle 7 (CDC7) inhibitor, is identified which can synergistically enhance the anti-tumor efficacy of Olaparib. Mechanistically, the combined administration of XL413 and Olaparib demonstrates considerable DNA damage and DNA replication stress, leading to increased sensitivity to Olaparib. Additionally, a robust type-I interferon response is triggered through the induction of the cGAS/STING signaling pathway. Using murine syngeneic tumor models, the combination treatment further demonstrates enhanced antitumor immunity, resulting in tumor regression. Collectively, this study presents an effective treatment strategy for patients with advanced OV by combining CDC7 inhibitors (CDC7i) and PARPi, offering a promising therapeutic approach for patients with limited response to PARPi.

A review on trends in development and translation of omics signatures in cancer

The field of cancer genomics and transcriptomics has evolved from targeted profiling to swift sequencing of individual tumor genome and transcriptome. The steady growth in genome, epigenome, and transcriptome datasets on a genome-wide scale has significantly increased our capability in capturing signatures that represent both the intrinsic and extrinsic biological features of tumors. These biological differences can help in precise molecular subtyping of cancer, predicting tumor progression, metastatic potential, and resistance to therapeutic agents. In this review, we summarized the current development of genomic, methylomic, transcriptomic, proteomic and metabolic signatures in the field of cancer research and highlighted their potentials in clinical applications to improve diagnosis, prognosis, and treatment decision in cancer patients.

Regulation of TAR DNA binding protein 43 (TDP-43) homeostasis by cytosolic DNA accumulation

TAR DNA-binding protein 43 (TDP-43) is a DNA/RNA binding protein predominantly localized in the nucleus under physiological conditions. TDP-43 proteinopathy, characterized by cytoplasmic aggregation and nuclear loss, is associated with many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Thus it is crucial to understand the molecular mechanism regulating TDP-43 homeostasis. Here, we show that the uptake of oligodeoxynucleotides (ODNs) from the extracellular space induces reversible TDP-43 cytoplasmic puncta formation in both neurons and glia. ODNs facilitate the liquid-liquid phase separation of TDP-43 in vitro. Importantly, persistent accumulation of DNA in the cytoplasm leads to nuclear depletion of TDP-43 and enhanced production of a short isoform of TDP-43 (sTDP-43). In addition, in response to ODN uptake, the nuclear import receptor karyopherin subunit β1 (KPNB1) is sequestered in the cytosolic TDP-43 puncta. ALS-linked Q331K mutation decreases the dynamics of cytoplasmic TDP-43 puncta and increases the levels of sTDP-43. Moreover, the TDP-43 cytoplasmic puncta are induced by DNA damage and by impaired nuclear envelope integrity due to Lamin A/C deficiency. In summary, our data support that abnormal DNA accumulation in the cytoplasm may be one of the key mechanisms leading to TDP-43 proteinopathy and provides novel insights into molecular mechanisms of ALS caused by TDP-43 mutations.

DNA damage response inhibitors in cancer therapy: lessons from the past, current status and future implications

The DNA damage response (DDR) is a network of proteins that coordinate DNA repair and cell-cycle checkpoints to prevent damage being transmitted to daughter cells. DDR defects lead to genomic instability, which enables tumour development, but they also create vulnerabilities that can be used for cancer therapy. Historically, this vulnerability has been taken advantage of using DNA-damaging cytotoxic drugs and radiotherapy, which are more toxic to tumour cells than to normal tissues. However, the discovery of the unique sensitivity of tumours defective in the homologous recombination DNA repair pathway to PARP inhibition led to the approval of six PARP inhibitors worldwide and to a focus on making use of DDR defects through the development of other DDR-targeting drugs. Here, we analyse the lessons learnt from PARP inhibitor development and how these may be applied to new targets to maximize success. We explore why, despite so much research, no other DDR inhibitor class has been approved, and only a handful have advanced to later-stage clinical trials. We discuss why more reliable predictive biomarkers are needed, explore study design from past and current trials, and suggest alternative models for monotherapy and combination studies. Targeting multiple DDR pathways simultaneously and potential combinations with anti-angiogenic agents or immune checkpoint inhibitors are also discussed.

Recent advancements in cGAS-STING activation, tumor immune evasion, and therapeutic implications

The cGAS-STING signaling pathway is indeed a pivotal component of the immune system and serve as a crucial link between innate and adaptive immune responses. STING is involved in the cellular response to pathogen invasion and DNA damage, and which has important consequences for host defense mechanisms and cancer regulation. Ongoing research aiming to modulate the cGAS-STING pathway for improved clinical outcomes in cancer and autoimmune diseases is underway. Indeed, the interaction between the cGAS-STING pathway and immune evasion mechanisms is a complex and critical aspect of cancer biology. Pathogens and various host factors can exploit this pathway to reduce the effectiveness of cancer therapies, particularly immunotherapies. Thus, immunotherapies or combination therapies may assist in overcoming the immune suppression and improving clinical outcomes. This review explores recent advancements in understanding the cGAS-STING signaling pathway, with particular emphasis on its activation mechanisms and role in tumor immune evasion. The dual role of the pathway in boosting immune responses while simultaneously enabling tumors to evade the immune system makes it a crucial target for innovative cancer treatment approaches.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 2 Given name: [Md Mazedul] Last name [Islam], Author 3 Given name: [Mst Rubaiat Nazneen] Last name [Akhand] and Author 5 Given name: [Md Rashedunnabi] Last name [Akanda]. Also, kindly confirm the details in the metadata are correct.AQ1: Here Author 4 given name: [Byung-Yong] Last name [Park] is missing. Metadata are correct.

DNA damage response in breast cancer and its significant role in guiding novel precise therapies

DNA damage response (DDR) deficiency has been one of the emerging targets in treating breast cancer in recent years. On the one hand, DDR coordinates cell cycle and signal transduction, whose dysfunction may lead to cell apoptosis, genomic instability, and tumor development. Conversely, DDR deficiency is an intrinsic feature of tumors that underlies their response to treatments that inflict DNA damage. In this review, we systematically explore various mechanisms of DDR, the rationale and research advances in DDR-targeted drugs in breast cancer, and discuss the challenges in its clinical applications. Notably, poly (ADP-ribose) polymerase (PARP) inhibitors have demonstrated favorable efficacy and safety in breast cancer with high homogenous recombination deficiency (HRD) status in a series of clinical trials. Moreover, several studies on novel DDR-related molecules are actively exploring to target tumors that become resistant to PARP inhibition. Before further clinical application of new regimens or drugs, novel and standardized biomarkers are needed to develop for accurately characterizing the benefit population and predicting efficacy. Despite the promising efficacy of DDR-related treatments, challenges of off-target toxicity and drug resistance need to be addressed. Strategies to overcome drug resistance await further exploration on DDR mechanisms, and combined targeted drugs or immunotherapy will hopefully provide more precise or combined strategies and expand potential responsive populations.

DNA methylation variations of DNA damage response correlate survival and local immune status in melanomas

AIM

We aimed to explore the impact of DNA methylation alterations on the DNA damage response (DDR) in melanoma prognosis and immunity. MATERIAL & METHODS: Different melanoma cohorts with molecular and clinical data were included.

RESULTS

Hierarchical clustering utilizing different combinations of DDR-relevant CpGs yielded distinct melanoma subtypes, which were characteristic of different prognoses, transcriptional function profiles of DDR, and immunity and immunotherapy responses but were associated with similar tumor mutation burdens. We then constructed and validated a clinically applicable 4-CpG risk-score signature for predicting survival and immunotherapy response.

CONCLUSION

Our study describes the close interrelationship among DNA methylation, DDR machinery, local tumor immune status, melanoma prognosis, and immunotherapy response.

Changes in immune cell subtypes during ageing

BACKGROUND

The immune system comprises many different types of cells, each with different functions and properties during immune defence. The numbers and types of immune cells in the circulation is highly dynamic and regulated by infections, ageing and certain types of cancers. It is recognised that immune function decreases during ageing, but the biological age at which these functional changes occur is variable, and how ageing affects the different sub-types of lymphocytes, monocytes and NK cells in the circulation is not fully defined.

METHODS

In this study, we recruited 24 healthy volunteers over the age range of 23y to 89y and measured the numbers of different subclasses of circulating cells by immuno-phenotyping and flow cytometry.

RESULTS

We show increased monocyte:lymphocyte ratios in a > 50y cohort and most T cell subsets were decreased, except for CD4+ cells, which were increased in this cohort. In addition, there was NK cell expansion and increased HLA-DR+ T cells, but decreased numbers of classical monocytes and increased numbers of CD4+ monocytes in this >50y cohort.

CONCLUSIONS

These data indicate that healthy ageing is associated with changes in both the major cell groups but also individual subclasses of cells, and these are likely to result from continuous immune challenge and impaired development.

Exogenous non-coding dsDNA-dependent trans-activation of phagocytes augments anti-tumor immunity

Stimulator of interferon genes (STING)-dependent signaling is requisite for effective anti-microbial and anti-tumor activity. STING signaling is commonly defective in cancer cells, which enables tumor cells to evade the immunosurveillance system. We evaluate here whether intrinsic STING signaling in such tumor cells could be reconstituted by creating recombinant herpes simplex viruses (rHSVs) that express components of the STING signaling pathway. We observe that rHSVs expressing STING and/or cGAS replicate inefficiently yet retain in vivo anti-tumor activity, independent of oncolytic activity requisite on the trans-activation of extrinsic STING signaling in phagocytes by engulfed microbial dsDNA species. Accordingly, the in vivo effects of virotherapy could be simulated by nanoparticles incorporating non-coding dsDNA species, which comparably elicit the trans-activation of phagocytes and augment the efficacy of established cancer treatments including checkpoint inhibition and radiation therapy. Our results help elucidate mechanisms of virotherapeutic anti-tumor activity as well as provide alternate strategies to treat cancer.

STING signalling compensates for low tumour mutation burden to drive anti-tumour immunity

BACKGROUND

While mutation-derived neoantigens are well recognized in generating anti-tumour T cell response, increasing evidences highlight the complex association between tumour mutation burden (TMB) and tumour infiltrating lymphocytes (TILs). The exploration of non-TMB determinants of active immune response could improve the prognosis prediction and provide guidance for current immunotherapy.

METHODS

The transcriptomic and whole exome sequence data in The Cancer Genome Atlas were used to examine the relationship between TMB and exhausted CD8+ T cells (Tex), as an indicator of tumour antigen-specific T cells across nine major cancer types. Computational clustering analysis was performed on 4510 tumours to identify different immune profiles. NanoString gene expression analysis and single cell RNA-seq analysis using fresh human breast cancer were performed for finding validation.

FINDINGS

TMB was found to be poorly correlated with active immune response in various cancer types. Patient clustering analysis revealed a group of tumours with abundant Tex but low TMB. In those tumours, we observed significantly higher expression of the stimulator of interferon genes (STING) signalling. Dendritic cells, particularly those of BATF3+ lineage, were also found to be essential for accumulation of Tex within tumours. Mechanistically, loss of genomic and cellular integrity, marked by decreased DNA damage repair, defective replication stress response, and increased apoptosis were shown to drive STING activation.

INTERPRETATION

These results highlight that TMB alone does not fully predict tumour immune profiles, with STING signalling compensating for low TMB in non-hypermutated tumours to enhance anti-tumour immunity. Translating these results, STING agonists may benefit patients with non-hypermutated tumours. STING activation may serve as an additional biomarker to predict response to immune checkpoint blockades alongside TMB. Our research also unravelled the interplay between genomic instability and STING activation, informing potential combined chemotherapy targeting the axis of genomic integrity and immunotherapy.

FUNDING

City of Hope Christopher Family Endowed Innovation Fund for Alzheimer's Disease and Breast Cancer Research in honor of Vineta Christopher; Breast Cancer Alliance Early Career Investigator Award; National Cancer Institute of the National Institutes of Health under award number R01CA256989 and R01CA240392.

Targeting ATR Pathway in Solid Tumors: Evidence of Improving Therapeutic Outcomes

The DNA damage response (DDR) system is a complicated network of signaling pathways that detects and repairs DNA damage or induces apoptosis. Critical regulators of the DDR network include the DNA damage kinases ataxia telangiectasia mutated Rad3-related kinase (ATR) and ataxia-telangiectasia mutated (ATM). The ATR pathway coordinates processes such as replication stress response, stabilization of replication forks, cell cycle arrest, and DNA repair. ATR inhibition disrupts these functions, causing a reduction of DNA repair, accumulation of DNA damage, replication fork collapse, inappropriate mitotic entry, and mitotic catastrophe. Recent data have shown that the inhibition of ATR can lead to synthetic lethality in ATM-deficient malignancies. In addition, ATR inhibition plays a significant role in the activation of the immune system by increasing the tumor mutational burden and neoantigen load as well as by triggering the accumulation of cytosolic DNA and subsequently inducing the cGAS-STING pathway and the type I IFN response. Taken together, we review stimulating data showing that ATR kinase inhibition can alter the DDR network, the immune system, and their interplay and, therefore, potentially provide a novel strategy to improve the efficacy of antitumor therapy, using ATR inhibitors as monotherapy or in combination with genotoxic drugs and/or immunomodulators.

The cell cycle revisited: DNA replication past S phase preserves genome integrity

Accurate and complete DNA duplication is critical for maintaining genome integrity. Multiple mechanisms regulate when and where DNA replication takes place, to ensure that the entire genome is duplicated once and only once per cell cycle. Although the bulk of the genome is copied during the S phase of the cell cycle, increasing evidence suggests that parts of the genome are replicated in G2 or mitosis, in a last attempt to secure that daughter cells inherit an accurate copy of parental DNA. Remaining unreplicated gaps may be passed down to progeny and replicated in the next G1 or S phase. These findings challenge the long-established view that genome duplication occurs strictly during the S phase, bridging DNA replication to DNA repair and providing novel therapeutic strategies for cancer treatment.

Advances in DNA damage response inhibitors in colorectal cancer therapy

One potential cause of cancer is genomic instability that arises in normal cells due to years of DNA damage in the body. The clinical application of radiotherapy and cytotoxic drugs to treat cancer is based on the principle of damaging the DNA of cancer cells. However, the benefits of these treatments also have negative effects on normal tissue. While there have been notable advancements in molecular-driven therapy and immunotherapy for colorectal cancer (CRC), a considerable portion of patients with advanced CRC do not experience any benefits from these treatments, leading to a poor prognosis. In recent years, targeted therapy aimed at suppressing the DNA damage response (DDR) in cancer cells has emerged as a potential treatment option for CRC patients, offering them more choices for treatment. Currently, the integration of DDR and clinical intervention remains in the exploratory phase. This review primarily elucidates the fundamental principles of DDR inhibitors, provides an overview of their current clinical application status in CRC, and discusses the advancements as well as limitations observed in relevant studies.

Olaparib plus Durvalumab, with or without Bevacizumab, as Treatment in PARP Inhibitor-Naïve Platinum-Sensitive Relapsed Ovarian Cancer: A Phase II Multi-Cohort Study

PURPOSE

Early results from the phase II MEDIOLA study (NCT02734004) in germline BRCA1- and/or BRCA2-mutated (gBRCAm) platinum-sensitive relapsed ovarian cancer (PSROC) showed promising efficacy and safety with olaparib plus durvalumab. We report efficacy and safety of olaparib plus durvalumab in an expansion cohort of women with gBRCAm PSROC (gBRCAm expansion doublet cohort) and two cohorts with non-gBRCAm PSROC, one of which also received bevacizumab (non-gBRCAm doublet and triplet cohorts).

PATIENTS AND METHODS

In this open-label, multicenter study, PARP inhibitor-naïve patients received olaparib plus durvalumab treatment until disease progression; the non-gBRCAm triplet cohort also received bevacizumab. Primary endpoints were objective response rate (ORR; gBRCAm expansion doublet cohort), disease control rate (DCR) at 24 weeks (non-gBRCAm cohorts), and safety (all cohorts).

RESULTS

The full analysis and safety analysis sets comprised 51, 32, and 31 patients in the gBRCAm expansion doublet, non-gBRCAm doublet, and non-gBRCAm triplet cohorts, respectively. ORR was 92.2% [95% confidence interval (CI), 81.1-97.8] in the gBRCAm expansion doublet cohort (primary endpoint); DCR at 24 weeks was 28.1% (90% CI, 15.5-43.9) in the non-gBRCAm doublet cohort (primary endpoint) and 74.2% (90% CI, 58.2-86.5) in the non-gBRCAm triplet cohort (primary endpoint). Grade ≥ 3 adverse events were reported in 47.1%, 65.6%, and 61.3% of patients in the gBRCAm expansion doublet, non-gBRCAm doublet, and non-gBRCAm triplet cohorts, respectively, most commonly anemia.

CONCLUSIONS

Olaparib plus durvalumab continued to show notable clinical activity in women with gBRCAm PSROC. Olaparib plus durvalumab with bevacizumab demonstrated encouraging clinical activity in women with non-gBRCAm PSROC. No new safety signals were identified.

Role of rs873601 Polymorphisms in Prognosis of Lung Cancer Patients Treated with Platinum-Based Chemotherapy

BACKGROUND

Lung cancer is still the most lethal malignancy in the world, according to the report of Cancer Statistics in 2021. Platinum-based chemotherapy combined with immunotherapy is the first-line treatment in lung cancer patients. However, the 5-year survival rate is always affected by the adverse reactions and drug resistance caused by platinum-based chemotherapy. DNA damage and repair system is one of the important mechanisms that can affect the response to chemotherapy and clinical outcomes in lung cancer patients.

OBJECTIVE

The objective of this study is to find the relationship between the polymorphisms of DNA repair genes with the prognosis of platinum-based chemotherapy in lung cancer patients.

PATIENTS AND METHODS

We performed genotyping in 17 single nucleotide polymorphisms (SNPs) of Excision Repair Cross-Complementation group (ERCC) genes and X-ray Repair Cross-Complementing (XRCC) genes of 345 lung cancer patients via Sequenom MassARRAY. We used Cox proportional hazard models, state, and plink to analyze the associations between SNPs and the prognosis of lung cancer patients.

RESULTS

We found that the ERCC5 rs873601 was associated with the overall survival time in lung cancer patients treated with platinum-based chemotherapy (p = 0.031). There were some polymorphisms that were related to the prognosis in specific subgroups of lung cancer. Rs873601 showed a great influence on the prognosis of patients more than 55 years, Small Cell Lung Cancer (SCLC), and smoking patients. Rs2444933 was associated with prognosis in age less than 55 years, SCLC, metastasis, and stage III/IV/ED patients. Rs3740051 played an important role in the prognosis of SCLC and metastasis patients. Rs1869641 was involved in the prognosis of SCLC patients. Rs1051685 was related to the prognosis in non-metastasis patients.

CONCLUSION

The ERCC5 rs873601 (G>A) was a valuable biomarker for predicting the prognosis in lung cancer patients treated with platinum-based chemotherapy.

CDC7 inhibition induces replication stress-mediated aneuploid cells with an inflammatory phenotype sensitizing tumors to immune checkpoint blockade

Serine/threonine kinase, cell division cycle 7 (CDC7) is critical for initiating DNA replication. TAK-931 is a specific CDC7 inhibitor, which is a next-generation replication stress (RS) inducer. This study preclinically investigates TAK-931 antitumor efficacy and immunity regulation. TAK-931 induce RS, generating senescence-like aneuploid cells, which highly expressed inflammatory cytokines and chemokines (senescence-associated secretory phenotype, SASP). In vivo multilayer-omics analyses in gene expression panel, immune panel, immunohistochemistry, RNA sequencing, and single-cell RNA sequencing reveal that the RS-mediated aneuploid cells generated by TAK-931 intensively activate inflammatory-related and senescence-associated pathways, resulting in accumulation of tumor-infiltrating immune cells and potent antitumor immunity and efficacy. Finally, the combination of TAK-931 and immune checkpoint inhibitors profoundly enhance antiproliferative activities. These findings suggest that TAK-931 has therapeutic antitumor properties and improved clinical benefits in combination with conventional immunotherapy.

Relationship among DDR gene mutations, TMB and PD-L1 in solid tumour genomes identified using clinically actionable biomarker assays

The DNA damage response (DDR) pathway regulates DNA repair and cell survival, and inactivating mutations in DDR genes can increase tumour mutational burden (TMB), a predictive biomarker of treatment benefit from anti-PD-1/PD-L1 immunotherapies. However, a better understanding of the relationship among specific DDR mutations, TMB and PD-L1 expression is needed to improve translational strategies. Here, we determined genomic alteration frequencies in selected DDR genes that are clinically actionable biomarkers and investigated their association with TMB and PD-L1 in bladder, colorectal, non-small cell lung, ovarian and prostate cancers using the FoundationInsights® web portal. Our results not only confirm known associations, such as mismatch repair and POLE gene mutations with high TMB, but also identify significant associations between mutations in the SWI/SNF chromatin remodelling genes ARID1A and SMARCA4 and high TMB in multiple tumour types. Mutations in the ATR gene were associated with high TMB in colorectal and prostate cancers; however, associations between individual DDR mutations and high PD-L1 expression were uncommon and tumour-type specific. Finally, we found that high TMB and high PD-L1 expression were poorly associated, emphasising their independence as predictive biomarkers for immune checkpoint inhibitor use.

DUBing Primary Tumors of the Central Nervous System: Regulatory Roles of Deubiquitinases

The ubiquitin proteasome system (UPS) utilizes an orchestrated enzymatic cascade of E1, E2, and E3 ligases to add single or multiple ubiquitin-like molecules as post-translational modification (PTM) to proteins. Ubiquitination can alter protein functions and/or mark ubiquitinated proteins for proteasomal degradation but deubiquitinases (DUBs) can reverse protein ubiquitination. While the importance of DUBs as regulatory factors in the UPS is undisputed, many questions remain on DUB selectivity for protein targeting, their mechanism of action, and the impact of DUBs on the regulation of diverse biological processes. Furthermore, little is known about the expression and role of DUBs in tumors of the human central nervous system (CNS). In this comprehensive review, we have used publicly available transcriptional datasets to determine the gene expression profiles of 99 deubiquitinases (DUBs) from five major DUB families in seven primary pediatric and adult CNS tumor entities. Our analysis identified selected DUBs as potential new functional players and biomarkers with prognostic value in specific subtypes of primary CNS tumors. Collectively, our analysis highlights an emerging role for DUBs in regulating CNS tumor cell biology and offers a rationale for future therapeutic targeting of DUBs in CNS tumors.

The Complex Network of ADP-Ribosylation and DNA Repair: Emerging Insights and Implications for Cancer Therapy

ADP-ribosylation is a post-translational modification of proteins that plays a key role in various cellular processes, including DNA repair. Recently, significant progress has been made in understanding the mechanism and function of ADP-ribosylation in DNA repair. ADP-ribosylation can regulate the recruitment and activity of DNA repair proteins by facilitating protein-protein interactions and regulating protein conformations. Moreover, ADP-ribosylation can influence additional post-translational modifications (PTMs) of proteins involved in DNA repair, such as ubiquitination, methylation, acetylation, phosphorylation, and SUMOylation. The interaction between ADP-ribosylation and these additional PTMs can fine-tune the activity of DNA repair proteins and ensure the proper execution of the DNA repair process. In addition, PARP inhibitors have been developed as a promising cancer therapeutic strategy by exploiting the dependence of certain cancer types on the PARP-mediated DNA repair pathway. In this paper, we review the progress of ADP-ribosylation in DNA repair, discuss the crosstalk of ADP-ribosylation with additional PTMs in DNA repair, and summarize the progress of PARP inhibitors in cancer therapy.

CD155 and its receptors in cancer immune escape and immunotherapy

In recent years, there have been multiple breakthroughs in cancer immunotherapy, with immune checkpoint inhibitors becoming the most promising treatment strategy. However, available drugs are not always effective. As an emerging immune checkpoint molecule, CD155 has become an important target for immunotherapy. This review describes the structure and function of CD155, its receptors TIGIT, CD96, and CD226, and summarizes that CD155 expressed by tumor cells can upregulate its expression through the DNA damage response pathway and Ras-Raf-MEK-ERK signaling pathway. This review also elaborates the mechanism of immune escape after binding CD155 to its receptors TIGIT, CD96, and CD226, and summarizes the current progress of immunotherapy research regarding CD155 and its receptors. Besides, it also discusses the future direction of checkpoint immunotherapy.

Nivolumab Plus Ipilimumab in Patients With Solid Tumors With ATM Mutations: Results From the Targeted Agent and Profiling Utilization Registry (TAPUR) Study

PURPOSE

The Targeted Agent and Profiling Utilization Registry Study is a phase II basket study evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancers with genomic alterations known to be drug targets. Results of a cohort of patients with solid tumors with ATM mutations treated with nivolumab plus ipilimumab are reported.

METHODS

Eligible patients had measurable disease (RECIST v.1.1), Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, and no standard treatment options. Primary end point was disease control (DC), defined as complete (CR) or partial (PR) response or stable disease (SD) of at least 16 weeks duration (SD16+). Low-accruing histology-specific cohorts with ATM mutations treated with nivolumab plus ipilimumab were collapsed into a single histology-pooled cohort for this analysis. The results were evaluated based on a one-sided exact binomial test with a null DC rate of 15% versus 35% (power = .84; α = .10). Secondary end points were objective response (OR), progression-free survival, overall survival, duration of response, duration of SD, and safety.

RESULTS

Twenty-nine patients with 10 tumor types with ATM mutations were enrolled from January 2018 to May 2020. One patient was not evaluable for efficacy. One CR, three PR, and three SD16+ were observed for DC and OR rates of 24% (P = .13; one-sided 90% CI: 14 to 100) and 14% (95% CI: 4 to 32), respectively. The null hypothesis of 15% DC rate was not rejected. Eleven patients had one treatment-related grade 3 adverse event (AE) or serious AE. There were two treatment-related patient deaths including immune-related encephalitis and respiratory failure.

CONCLUSION

Nivolumab plus ipilimumab did not meet prespecified criteria to declare a signal of activity in patients with solid tumors with ATM mutations.

Targeting DNA Damage Repair and Immune Checkpoint Proteins for Optimizing the Treatment of Endometrial Cancer

The dependence of cancer cells on the DNA damage response (DDR) pathway for the repair of endogenous- or exogenous-factor-induced DNA damage has been extensively studied in various cancer types, including endometrial cancer (EC). Targeting one or more DNA damage repair protein with small molecules has shown encouraging treatment efficacy in preclinical and clinical models. However, the genes coding for DDR factors are rarely mutated in EC, limiting the utility of DDR inhibitors in this disease. In the current review, we recapitulate the functional role of the DNA repair system in the development and progression of cancer. Importantly, we discuss strategies that target DDR proteins, including PARP, CHK1 and WEE1, as monotherapies or in combination with cytotoxic agents in the treatment of EC and highlight the compounds currently being evaluated for their efficacy in EC in clinic. Recent studies indicate that the application of DNA damage agents in cancer cells leads to the activation of innate and adaptive immune responses; targeting immune checkpoint proteins could overcome the immune suppressive environment in tumors. We further summarize recently revolutionized immunotherapies that have been completed or are now being evaluated for their efficacy in advanced EC and propose future directions for the development of DDR-based cancer therapeutics in the treatment of EC.

Small cytosolic double-stranded DNA represses cyclic GMP-AMP synthase activation and induces autophagy

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway is a major mediator of inflammation following stimulation with >45 bp double-stranded DNA (dsDNA). Herein, we identify a class of ∼20-40 bp small cytosolic dsDNA (scDNA) molecules that compete with long dsDNA (200-1,500 bp herring testis [HT]-DNA) for binding to cGAS, thus repressing HT-DNA-induced cGAS activation. The scDNA promotes cGAS and Beclin-1 interaction, releasing Rubicon, a negative regulator of phosphatidylinositol 3-kinase class III (PI3KC3), from the Beclin-1-PI3KC3 complex. This leads to PI3KC3 activation and induces autophagy, causing degradation of STING and long cytosolic dsDNA. Moreover, DNA damage decreases, and autophagy inducers increase scDNA levels. scDNA transfection and treatment with autophagy inducers attenuate DNA damage-induced cGAS activation. Thus, scDNA molecules serve as effective brakes for cGAS activation, preventing excessive inflammatory cytokine production following DNA damage. Our findings may have therapeutic implications for cytosolic DNA-associated inflammatory diseases.

Upregulation of FAM50A promotes cancer development

FAM50A encodes a nuclear protein involved in mRNA processing; however, its role in cancer development remains unclear. Herein, we conducted an integrative pan-cancer analysis using The Cancer Genome Atlas, Genotype-Tissue Expression, and the Clinical Proteomic Tumor Analysis Consortium databases. Based on the gene expression data from TCGA and GTEx databases, we compared FAM50A mRNA levels in 33 types of human cancer tissues to those in corresponding normal tissues and found that FAM50A mRNA level was upregulated in 20 of the 33 types of common cancer tissues. Then, we compared the DNA methylation status of the FAM50A promoter in tumor tissues to that in corresponding normal tissues. FAM50A upregulation was accompanied by promoter hypomethylation in 8 of the 20 types of tumor tissues, suggesting that promoter hypomethylation contributes to the upregulation of FAM50A in these cancer tissues. Elevated FAM50A expression in 10 types of cancer tissues was associated with poor prognosis in patients with cancer. FAM50A expression was positively correlated with CD4+ T-lymphocyte and dendritic cell infiltration in cancer tissues but was negatively correlated with CD8+ T-cell infiltration in cancer tissues. FAM50A knockdown caused DNA damage, induced interferon beta and interleukin-6 expression, and repressed the proliferation, invasion, and migration of cancer cells. Our findings indicate that FAM50A might be useful in cancer detection, reveal insights into its role in cancer development, and may contribute to the development of cancer diagnostics and treatments.

Revolutionizing DNA repair research and cancer therapy with CRISPR-Cas screens

All organisms possess molecular mechanisms that govern DNA repair and associated DNA damage response (DDR) processes. Owing to their relevance to human disease, most notably cancer, these mechanisms have been studied extensively, yet new DNA repair and/or DDR factors and functional interactions between them are still being uncovered. The emergence of CRISPR technologies and CRISPR-based genetic screens has enabled genome-scale analyses of gene-gene and gene-drug interactions, thereby providing new insights into cellular processes in distinct DDR-deficiency genetic backgrounds and conditions. In this Review, we discuss the mechanistic basis of CRISPR-Cas genetic screening approaches and describe how they have contributed to our understanding of DNA repair and DDR pathways. We discuss how DNA repair pathways are regulated, and identify and characterize crosstalk between them. We also highlight the impacts of CRISPR-based studies in identifying novel strategies for cancer therapy, and in understanding, overcoming and even exploiting cancer-drug resistance, for example in the contexts of PARP inhibition, homologous recombination deficiencies and/or replication stress. Lastly, we present the DDR CRISPR screen (DDRcs) portal , in which we have collected and reanalysed data from CRISPR screen studies and provide a tool for systematically exploring them.

Poly(ADP-ribose) polymerase 9 mediates early protection against Mycobacterium tuberculosis infection by regulating type I IFN production

The ADP ribosyltransferases (PARPs 1-17) regulate diverse cellular processes, including DNA damage repair. PARPs are classified on the basis of their ability to catalyze poly-ADP-ribosylation (PARylation) or mono-ADP-ribosylation (MARylation). Although PARP9 mRNA expression is significantly increased in progressive tuberculosis (TB) in humans, its participation in host immunity to TB is unknown. Here, we show that PARP9 mRNA encoding the MARylating PARP9 enzyme was upregulated during TB in humans and mice and provide evidence of a critical modulatory role for PARP9 in DNA damage, cyclic GMP-AMP synthase (cGAS) expression, and type I IFN production during TB. Thus, Parp9-deficient mice were susceptible to Mycobacterium tuberculosis infection and exhibited increased TB disease, cGAS and 2'3'-cyclic GMP-AMP (cGAMP) expression, and type I IFN production, along with upregulation of complement and coagulation pathways. Enhanced M. tuberculosis susceptibility is type I IFN dependent, as blockade of IFN α receptor (IFNAR) signaling reversed the enhanced susceptibility of Parp9-/- mice. Thus, in sharp contrast to PARP9 enhancement of type I IFN production in viral infections, this member of the MAR family plays a protective role by limiting type I IFN responses during TB.

The mechanism and clinical application of DNA damage repair inhibitors combined with immune checkpoint inhibitors in the treatment of urologic cancer

Urologic cancers such as kidney, bladder, prostate, and uroepithelial cancers have recently become a considerable global health burden, and the response to immunotherapy is limited due to immune escape and immune resistance. Therefore, it is crucial to find appropriate and effective combination therapies to improve the sensitivity of patients to immunotherapy. DNA damage repair inhibitors can enhance the immunogenicity of tumor cells by increasing tumor mutational burden and neoantigen expression, activating immune-related signaling pathways, regulating PD-L1 expression, and reversing the immunosuppressive tumor microenvironment to activate the immune system and enhance the efficacy of immunotherapy. Based on promising experimental results from preclinical studies, many clinical trials combining DNA damage repair inhibitors (e.g., PARP inhibitors and ATR inhibitors) with immune checkpoint inhibitors (e.g., PD-1/PD-L1 inhibitors) are underway in patients with urologic cancers. Results from several clinical trials have shown that the combination of DNA damage repair inhibitors with immune checkpoint inhibitors can improve objective rates, progression-free survival, and overall survival (OS) in patients with urologic tumors, especially in patients with defective DNA damage repair genes or a high mutational load. In this review, we present the results of preclinical and clinical trials of different DNA damage repair inhibitors in combination with immune checkpoint inhibitors in urologic cancers and summarize the potential mechanism of action of the combination therapy. Finally, we also discuss the challenges of dose toxicity, biomarker selection, drug tolerance, drug interactions in the treatment of urologic tumors with this combination therapy and look into the future direction of this combination therapy.

MUC1-C Dictates PBRM1-Mediated Chronic Induction of Interferon Signaling, DNA Damage Resistance, and Immunosuppression in Triple-Negative Breast Cancer

The polybromo-1 (PBRM1) chromatin-targeting subunit of the SWI/SNF PBAF chromatin remodeling complex drives DNA damage resistance and immune evasion in certain cancer cells through mechanisms that remain unclear. STAT1 and IRF1 are essential effectors of type I and II IFN pathways. Here, we report that MUC1-C is necessary for PBRM1 expression and that it forms a nuclear complex with PBRM1 in triple-negative breast cancer (TNBC) cells. Analysis of global transcriptional (RNA-seq) and chromatin accessibility (ATAC-seq) profiles further demonstrated that MUC1-C and PBRM1 drive STAT1 and IRF1 expression by increasing chromatin accessibility of promoter-like signatures (PLS) on their respective genes. We also found that MUC1-C, PBRM1, and IRF1 increase the expression and chromatin accessibility on PLSs of the (i) type II IFN pathway IDO1 and WARS genes and (ii) type I IFN pathway RIG-I, MDA5, and ISG15 genes that collectively contribute to DNA damage resistance and immune evasion. In support of these results, targeting MUC1-C in wild-type BRCA TNBC cells enhanced carboplatin-induced DNA damage and the loss of self-renewal capacity. In addition, MUC1-C was necessary for DNA damage resistance, self-renewal, and tumorigenicity in olaparib-resistant BRCA1-mutant TNBC cells. Analysis of TNBC tumors corroborated that (i) MUC1 and PBRM1 are associated with decreased responsiveness to chemotherapy and (ii) MUC1-C expression is associated with the depletion of tumor-infiltrating lymphocytes (TIL). These findings demonstrate that MUC1-C activates PBRM1, and thereby chromatin remodeling of IFN-stimulated genes that promote chronic inflammation, DNA damage resistance, and immune evasion.

IMPLICATIONS

MUC1-C is necessary for PBRM1-driven chromatin remodeling in chronic activation of IFN pathway genes that promote DNA damage resistance and immunosuppression.

DNA Damage and Its Role in Cancer Therapeutics

DNA damage is a double-edged sword in cancer cells. On the one hand, DNA damage exacerbates gene mutation frequency and cancer risk. Mutations in key DNA repair genes, such as breast cancer 1 (BRCA1) and/or breast cancer 2 (BRCA2), induce genomic instability and promote tumorigenesis. On the other hand, the induction of DNA damage using chemical reagents or radiation kills cancer cells effectively. Cancer-burdening mutations in key DNA repair-related genes imply relatively high sensitivity to chemotherapy or radiotherapy because of reduced DNA repair efficiency. Therefore, designing specific inhibitors targeting key enzymes in the DNA repair pathway is an effective way to induce synthetic lethality with chemotherapy or radiotherapy in cancer therapeutics. This study reviews the general pathways involved in DNA repair in cancer cells and the potential proteins that could be targeted for cancer therapeutics.

The schedule of ATR inhibitor AZD6738 can potentiate or abolish antitumor immune responses to radiotherapy

Inhibitors of the DNA damage signaling kinase ATR increase tumor cell killing by chemotherapies that target DNA replication forks but also kill rapidly proliferating immune cells including activated T cells. Nevertheless, ATR inhibitor (ATRi) and radiotherapy (RT) can be combined to generate CD8+ T cell-dependent antitumor responses in mouse models. To determine the optimal schedule of ATRi and RT, we determined the impact of short-course versus prolonged daily treatment with AZD6738 (ATRi) on responses to RT (days 1-2). Short-course ATRi (days 1-3) plus RT caused expansion of tumor antigen-specific, effector CD8+ T cells in the tumor-draining lymph node (DLN) at 1 week after RT. This was preceded by acute decreases in proliferating tumor-infiltrating and peripheral T cells and a rapid proliferative rebound after ATRi cessation, increased inflammatory signaling (IFN-β, chemokines, particularly CXCL10) in tumors, and an accumulation of inflammatory cells in the DLN. In contrast, prolonged ATRi (days 1-9) prevented the expansion of tumor antigen-specific, effector CD8+ T cells in the DLN, and entirely abolished the therapeutic benefit of short-course ATRi with RT and anti-PD-L1. Our data argue that ATRi cessation is essential to allow CD8+ T cell responses to both RT and immune checkpoint inhibitors.

Targeting replication stress in cancer therapy

Replication stress is a major cause of genomic instability and a crucial vulnerability of cancer cells. This vulnerability can be therapeutically targeted by inhibiting kinases that coordinate the DNA damage response with cell cycle control, including ATR, CHK1, WEE1 and MYT1 checkpoint kinases. In addition, inhibiting the DNA damage response releases DNA fragments into the cytoplasm, eliciting an innate immune response. Therefore, several ATR, CHK1, WEE1 and MYT1 inhibitors are undergoing clinical evaluation as monotherapies or in combination with chemotherapy, poly[ADP-ribose]polymerase (PARP) inhibitors, or immune checkpoint inhibitors to capitalize on high replication stress, overcome therapeutic resistance and promote effective antitumour immunity. Here, we review current and emerging approaches for targeting replication stress in cancer, from preclinical and biomarker development to clinical trial evaluation.

Multiparameter single-cell proteomic technologies give new insights into the biology of ovarian tumors

High-grade serous ovarian cancer (HGSOC) is the most lethal gynecological malignancy. Its diagnosis at advanced stage compounded with its excessive genomic and cellular heterogeneity make curative treatment challenging. Two critical therapeutic challenges to overcome are carboplatin resistance and lack of response to immunotherapy. Carboplatin resistance results from diverse cell autonomous mechanisms which operate in different combinations within and across tumors. The lack of response to immunotherapy is highly likely to be related to an immunosuppressive HGSOC tumor microenvironment which overrides any clinical benefit. Results from a number of studies, mainly using transcriptomics, indicate that the immune tumor microenvironment (iTME) plays a role in carboplatin response. However, in patients receiving treatment, the exact mechanistic details are unclear. During the past decade, multiplex single-cell proteomic technologies have come to the forefront of biomedical research. Mass cytometry or cytometry by time-of-flight, measures up to 60 parameters in single cells that are in suspension. Multiplex cellular imaging technologies allow simultaneous measurement of up to 60 proteins in single cells with spatial resolution and interrogation of cell-cell interactions. This review suggests that functional interplay between cell autonomous responses to carboplatin and the HGSOC immune tumor microenvironment could be clarified through the application of multiplex single-cell proteomic technologies. We conclude that for better clinical care, multiplex single-cell proteomic technologies could be an integral component of multimodal biomarker development that also includes genomics and radiomics. Collection of matched samples from patients before and on treatment will be critical to the success of these efforts.

Models for Predicting Response to Immunotherapy and Prognosis in Patients with Gastric Cancer: DNA Damage Response Genes

Objective

DNA damage response (DDR) is a complex system that maintains genetic integrity and the stable replication and transmission of genetic material. m6A modifies DDR-related gene expression and affects the balance of DNA damage response in tumor cells. In this study, a risk model based on m6A-modified DDR-related gene was established to evaluate its role in patients with gastric cancer.

Methods

We downloaded 639 DNA damage response genes from the Gene Set Enrichment Analysis (GSEA) database and constructed risk score models using typed differential genes. We used Kaplan-Meier curves and risk curves to verify the clinical relevance of the model, which was then validated with the univariate and multifactorial Cox analysis, ROC, C-index, and nomogram, and finally this model was used to evaluate the correlation of the risk score model with immune microenvironment, microsatellite instability (MSI), tumor mutational burden (TMB), and immune checkpoints.

Results

In this study, 337 samples in The Cancer Genome Atlas (TCGA) database were used as training set to construct a DDR-related gene model, and GSE84437 was used as external data set for verification. We found that the prognosis and immunotherapy effect of gastric cancer patients in the low-risk group were significantly better than those in the high-risk group.

Conclusion

We screened eight DDR-related genes (ZBTB7A, POLQ, CHEK1, NPDC1, RAMP1, AXIN2, SFRP2, and APOD) to establish a risk model, which can predict the prognosis of gastric cancer patients and guide the clinical implementation of immunotherapy.

Triple kill: DDR inhibitors, radiotherapy and immunotherapy leave cancer cells with no escape

Radiotherapy (RT) has been widely used in the clinical treatment of cancers, but radiotherapy resistance (RR) leads to RT failure, tumor recurrence and metastasis. Many studies have been performed on the potential mechanisms behind RR, and a strong link has been found between RR and DNA damage. RT-induced DNA damage triggers a protective mechanism called the DNA damage response (DDR). DDR consists of several aspects, including the detection of DNA damage and induction of cell cycle checkpoint, DNA repair, and eventual induction of cell death. A large number of studies have shown that DDR inhibition leads to significantly enhanced sensitivity of cancer cells to RT. DDR may be an effective target for radio- and chemo-sensitization during cancer treatment. Therefore, many inhibitors of important enzymes involved in the DDR have been developed, such as PARP inhibitors, DNA-PK inhibitors, and ATM/ATR inhibitors. In addition, DNA damage also triggers the cGAS-STING signaling pathway and the ATM/ATR (CHK)/STAT pathway to induce immune infiltration and T-cell activation. This review discusses the effects of DDR pathway dysregulation on the tumor response to RT and the strategies for targeting these pathways to increase tumor susceptibility to RT. Finally, the potential for the combination treatment of radiation, DDR inhibition, and immunotherapy is described.

Anti-cancer immune responses to DNA damage response inhibitors: Molecular mechanisms and progress toward clinical translation

DNA damage response inhibitors are widely used anti-cancer agents that have potent activity against tumor cells with deficiencies in various DNA damage response proteins such as BRCA1/2. Inhibition of other proteins in this pathway including PARP, DNA-PK, WEE1, CHK1/2, ATR, or ATM can sensitize cancer cells to radiotherapy and chemotherapy, and such combinations are currently being tested in clinical trials for treatment of many malignancies including breast, ovarian, rectal, and lung cancer. Unrepaired DNA damage induced by DNA damage response inhibitors alone or in combination with radio- or chemotherapy has a direct cytotoxic effect on cancer cells and can also engage anti-cancer innate and adaptive immune responses. DNA damage-induced immune stimulation occurs by a variety of mechanisms including by the cGAS/STING pathway, STAT1 and downstream TRAIL pathway activation, and direct immune cell activation. Whether or not the relative contribution of these mechanisms varies after treatment with different DNA damage response inhibitors or across cancers with different genetic aberrations in DNA damage response enzymes is not well-characterized, limiting the design of optimal combinations with radio- and chemotherapy. Here, we review how the inhibition of key DNA damage response enzymes including PARP, DNA-PK, WEE1, CHK1/2, ATR, and ATM induces innate and adaptive immune responses alone or in combination with radiotherapy, chemotherapy, and/or immunotherapy. We also discuss current progress in the clinical translation of immunostimulatory DNA-damaging treatment regimens and necessary future directions to optimize the immune-sensitizing potential of DNA damage response inhibitors.

Balancing Affinity, Selectivity, and Cytotoxicity of Hydrazone-Based G-Quadruplex Ligands for Activation of Interferon β Genes in Cancer Cells

G-quadruplex (G4) ligands are investigated to discover new anticancer drugs with increased cell-killing potency. These ligands can induce genome instability and activate innate immune genes at non-cytotoxic doses, opening the discovery of cytostatic immune-stimulating ligands. However, the interplay of G4 affinity/selectivity with cytotoxicity and immune gene activation is not well-understood. We investigated a series of closely related hydrazone derivatives to define the molecular bases of immune-stimulation activity. Although they are closely related to each other, such derivatives differ in G4 affinity, cytotoxicity, genome instability, and immune gene activation. Our findings show that G4 affinity of ligands is a critical feature for immune gene activation, whereas a high cytotoxic potency interferes with it. The balance of G4 stabilization versus cytotoxicity can determine the level of immune gene activation in cancer cells. Thus, we propose a new rationale based on low cell-killing potency and high immune stimulation to discover effective anticancer G4 ligands.

The role of DNA damage repair (DDR) system in response to immune checkpoint inhibitor (ICI) therapy

As our understanding of the mechanisms of cancer treatment has increased, a growing number of studies demonstrate pathways through which DNA damage repair (DDR) affects the immune system. At the same time, the varied response of patients to immune checkpoint blockade (ICB) therapy has prompted the discovery of various predictive biomarkers and the study of combination therapy. Here, our investigation explores the interactions involved in combination therapy, accompanied by a review that summarizes currently identified and promising predictors of response to immune checkpoint inhibitors (ICIs) that are useful for classifying oncology patients. In addition, this work, which discusses immunogenicity and several components of the tumor immune microenvironment, serves to illustrate the mechanism by which higher response rates and improved efficacy of DDR inhibitors (DDRi) in combination with ICIs are achieved.

PBAF loss leads to DNA damage-induced inflammatory signaling through defective G2/M checkpoint maintenance

The PBRM1 subunit of the PBAF (SWI/SNF) chromatin remodeling complex is mutated in ∼40% of clear cell renal cancers. PBRM1 loss has been implicated in responses to immunotherapy in renal cancer, but the mechanism is unclear. DNA damage-induced inflammatory signaling is an important factor determining immunotherapy response. This response is kept in check by the G2/M checkpoint, which prevents progression through mitosis with unrepaired damage. We found that in the absence of PBRM1, p53-dependent p21 up-regulation is delayed after DNA damage, leading to defective transcriptional repression by the DREAM complex and premature entry into mitosis. Consequently, DNA damage-induced inflammatory signaling pathways are activated by cytosolic DNA. Notably, p53 is infrequently mutated in renal cancer, so PBRM1 mutational status is critical to G2/M checkpoint maintenance. Moreover, we found that the ability of PBRM1 deficiency to predict response to immunotherapy correlates with expression of the cytosolic DNA-sensing pathway in clinical samples. These findings have implications for therapeutic responses in renal cancer.

Emerging role of the cGAS-STING signaling pathway in autoimmune diseases: Biologic function, mechanisms and clinical prospection

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway, as vital component of innate immune system, acts a vital role in distinguishing invasive pathogens and cytosolic DNA. Cytosolic DNA sensor cGAS first binds to cytosolic DNA and catalyze synthesis of cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), which is known as the secondmessenger. Next, cGAMP activates the adaptor protein STING, triggering a molecular chain reaction to stimulate cytokines including interferons (IFNs). Recently, many researches have revealed that the regulatory role of cGAS-STING signaling pathway in autoimmune diseases (AIDs) such as Rheumatoid arthritis (RA), Aicardi Goutières syndrome (AGS) and systemic lupus erythematosus (SLE). Moreover, accumulated evidence showed inhibition of the cGAS-STING signaling pathway can remarkably suppress joint swelling and inflammatory cell infiltration in RA mice. Therefore, in this review, we describe the molecular properties, biologic function and mechanisms of the cGAS-STING signaling pathway in AIDs. In addition, potential clinical applications especially selective small molecule inhibitors targeting the cGAS-STING signaling pathway are also discussed.

A Non-Cell-Autonomous Mode of DNA Damage Response in Soma of Caenorhabditis elegans

Life has evolved a mechanism called DNA damage response (DDR) to sense, signal and remove/repair DNA damage, and its deficiency and dysfunction usually lead to genomic instability and development of cancer. The signaling mode of the DDR has been believed to be of cell-autonomy. However, the paradigm is being shifted with in-depth research into model organism Caenorhabditis elegans. Here, we mainly investigate the effect of DDR activation on the radiosensitivity of vulva of C. elegans, and first found that the vulval radiosensitivity is mainly regulated by somatic DDR, rather than the DDR of germline. Subsequently, the worm lines with pharynx-specific rescue of DDR were constructed, and it is shown that the 9-1-1-ATR and MRN-ATM cascades in pharynx restore approximately 90% and 70% of vulval radiosensitivity, respectively, through distantly regulating the NHEJ repair of vulval cells. The results suggest that the signaling cascade of DDR might also operate in a non-cell autonomous mode. To further explore the underlying regulatory mechanisms, the cpr-4 mutated gene is introduced into the DDR-rescued worms, and CPR-4, a cysteine protease cathepsin B, is confirmed to mediate the inter-tissue and inter-individual regulation of DDR as a signaling molecule downstream of 9-1-1-ATR. Our findings throw some light on the regulation of DNA repair in soma of C. elegans, and might also provide new cues for cancer prevention and treatment.

DNA-PK Inhibition and Radiation Promote Antitumoral Immunity through RNA Polymerase III in Pancreatic Cancer

Targeting the DNA damage response in combination with radiation enhances type I interferon (T1IFN)-driven innate immune signaling. It is not understood, however, whether DNA-dependent protein kinase (DNA-PK), the kinase critical for repairing the majority of radiation-induced DNA double-strand breaks in cancer cells, is immunomodulatory. We show that combining radiation with DNA-PK inhibition increases cytosolic double-stranded DNA and tumoral T1IFN signaling in a cyclic GMP-AMP synthase (cGAS)- and stimulator of interferon genes (STING)-independent, but an RNA polymerase III (POL III), retinoic acid-inducible gene I (RIG-I), and antiviral-signaling protein (MAVS)-dependent manner. Although DNA-PK inhibition and radiation also promote programmed death-ligand 1 (PD-L1) expression, the use of anti-PD-L1 in combination with radiation and DNA-PK inhibitor potentiates antitumor immunity in pancreatic cancer models. Our findings demonstrate a novel mechanism for the antitumoral immune effects of DNA-PK inhibitor and radiation that leads to increased sensitivity to anti-PD-L1 in poorly immunogenic pancreatic cancers.

IMPLICATIONS

Our work nominates a novel therapeutic strategy as well as its cellular mechanisms pertinent for future clinical trials combining M3814, radiation, and anti-PD-L1 antibody in patients with pancreatic cancer.

Opinion: PARP inhibitors in cancer-what do we still need to know?

PARP inhibitors (PARPi) have been demonstrated to exhibit profound anti-tumour activity in individuals whose cancers have a defect in the homologous recombination DNA repair pathway. Here, we describe the current consensus as to how PARPi work and how drug resistance to these agents emerges. We discuss the need to refine the current repertoire of clinical-grade companion biomarkers to be used with PARPi, so that patient stratification can be improved, the early emergence of drug resistance can be detected and dose-limiting toxicity can be predicted. We also highlight current thoughts about how PARPi resistance might be treated.

Diagnostic, Prognostic, and Immunological Roles of HELLS in Pan-Cancer: A Bioinformatics Analysis

Background

Inappropriate repair of DNA damage drives carcinogenesis. Lymphoid-specific helicase (HELLS) is an important component of the chromatin remodeling complex that helps repair DNA through various mechanisms such as DNA methylation, histone posttranslational modification, and nucleosome remodeling. Its role in human cancer initiation and progression has garnered recent attention. Our study aims to provide a more systematic and comprehensive understanding of the role of HELLS in the development and progression of multiple malignancies through analysis of HELLS in cancers.

Methods

We explored the role of HELLS in cancers using The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) database. Multiple web platforms and software were used for data analysis, including R, Cytoscape, HPA, Archs4, TISIDB, cBioPortal, STRING, GSCALite, and CancerSEA.

Results

High HELLS expression was found in a variety of cancers and differentially expressed across molecular and immune subtypes. HELLS was involved in many cancer pathways. Its expression positively correlated with Th2 and Tcm cells in most cancers. It also correlated with genetic markers of immunomodulators in various cancers.

Conclusions

Our study elucidates the role HELLS plays in promotion, inhibition, and treatment of different cancers. HELLS is a potential cancer diagnostic and prognostic biomarker with immune, targeted, or cytotoxic therapeutic value. This work is a prerequisite to clinical validation and treatment of HELLS in cancers.

Lisinopril Can Reduce Genotoxicity of L-Asparaginase in Bone Marrow Stem Cells

BACKGROUND: Lisinopril is a medication used to lower blood pressure by inhibiting the angiotensin-converting enzyme (ACE). L-asparaginase is a chemotherapeutic agent used to treat acute lymphoblastic leukemia.    AIM: To Study the effect of lisinopril on the genotoxicity of L-asparaginase (ASNase) in bone marrow stem cells.   METHODS: Albino Swiss male mice were divided into three groups. The first group was treated with lisinopril 10 mg/kg/day for 14 days. The second group mice were injected with L-asparaginase 3000 IU/kg. The last group was treated with of lisinopril for 14 days followed with an intraperitoneal injection of L-asparaginase (ASNase) at the end of the 13th day. Genotoxicity was assessed by calculating the percentage of micronucleus (MN) and mitotic index (MI).   RESULTS:   ASNase significantly increased genotoxicity by raising the %MN and lowering % MI. When Lisinopril 10 mg/kg/day was administered no significant effect was seen. However, a significant decrease in genotoxic effects was observed when mice receiving Lisinopril were injected with 3000 IU/kg ASNase as compared the group treated with ASNase alone. This effect was manifested by decreasing %MN and increasing %MI.     CONCLUSION:  Using lisinopril for blood hypertension treatments concurrently with the cancer therapeutic agent, L- asparaginase, decreased its genotoxicity in bone marrow stem cells.

STING agonism reprograms tumor-associated macrophages and overcomes resistance to PARP inhibition in BRCA1-deficient models of breast cancer

PARP inhibitors (PARPi) have drastically changed the treatment landscape of advanced ovarian tumors with BRCA mutations. However, the impact of this class of inhibitors in patients with advanced BRCA-mutant breast cancer is relatively modest. Using a syngeneic genetically-engineered mouse model of breast tumor driven by Brca1 deficiency, we show that tumor-associated macrophages (TAMs) blunt PARPi efficacy both in vivo and in vitro. Mechanistically, BRCA1-deficient breast tumor cells induce pro-tumor polarization of TAMs, which in turn suppress PARPi-elicited DNA damage in tumor cells, leading to reduced production of dsDNA fragments and synthetic lethality, hence impairing STING-dependent anti-tumor immunity. STING agonists reprogram M2-like pro-tumor macrophages into an M1-like anti-tumor state in a macrophage STING-dependent manner. Systemic administration of a STING agonist breaches multiple layers of tumor cell-mediated suppression of immune cells, and synergizes with PARPi to suppress tumor growth. The therapeutic benefits of this combination require host STING and are mediated by a type I IFN response and CD8+ T cells, but do not rely on tumor cell-intrinsic STING. Our data illustrate the importance of targeting innate immune suppression to facilitate PARPi-mediated engagement of anti-tumor immunity in breast cancer.

The translational challenges of precision oncology

The translational challenges in the field of precision oncology are in part related to the biological complexity and diversity of this disease. Technological advances in genomics have facilitated large sequencing efforts and discoveries that have further supported this notion. In this review, we reflect on the impact of these discoveries on our understanding of several concepts: cancer initiation, cancer prevention, early detection, adjuvant therapy and minimal residual disease monitoring, cancer drug resistance, and cancer evolution in metastasis. We discuss key areas of focus for improving cancer outcomes, from biological insights to clinical application, and suggest where the development of these technologies will lead us. Finally, we discuss practical challenges to the wider adoption of molecular profiling in the clinic and the need for robust translational infrastructure.

Targeting PARP1 to Enhance Anticancer Checkpoint Immunotherapy Response: Rationale and Clinical Implications

Reinvigorating the antitumor immune response using immune checkpoint inhibitors (ICIs) has revolutionized the treatment of several malignancies. However, extended use of ICIs has resulted in a cancer-specific response. In tumors considered to be less immunogenic, the response rates were low or null. To overcome resistance and improve the beneficial effects of ICIs, novel strategies focused on ICI-combined therapies have been tested. In particular, poly ADP-ribose polymerase inhibitors (PARPi) are a class of agents with potential for ICI combined therapy. PARPi impairs single-strand break DNA repair; this mechanism involves synthetic lethality in tumor cells with deficient homologous recombination. More recently, novel evidence indicated that PAPRi has the potential to modulate the antitumor immune response by activating antigen-presenting cells, infiltrating effector lymphocytes, and upregulating programmed death ligand-1 in tumors. This review covers the current advances in the immune effects of PARPi, explores the potential rationale for combined therapy with ICIs, and discusses ongoing clinical trials.