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Cancer incidence in urban bus drivers and tramway employees: a retrospective cohort study.

OBJECTIVE: To investigate the risk of cancer associated with exposure to air pollution among bus drivers and tramway employees. METHODS: A retrospective cohort study of 18,174 bus drivers or tramway employees in Copenhagen in the period 1900-94. Data on employment were obtained from company files. Information on cancer was obtained from the Danish Cancer Registry. RESULTS: Findings showed that bus drivers or tramway employees had an increased risk of all malignant neoplasms (standardised incidence ratio (SIR) 1.24, 95% confidence interval (95% CI) 1.19 to 1.30). The relative risk was significantly increased for both men and women (SIR 1.24, 95% CI 1.19 to 1.30 and 1.28, 1.06 to 1.53, respectively). People employed for < 3 months had no increased risk of cancer (1.04, 0.81 to 1.31). For men who were employed for > 3 months the risk of lung cancer (1.6, 1.5 to 1.8), laryngeal cancer (1.4, 1.0 to 1.9), kidney cancer (1.6, 1.3 to 2.0), bladder cancer (1.4, 1.2 to 1.6), skin cancer (1.1, 1.0 to 1.2), pharyngeal cancer (1.9, 1.2 to 2.8), rectal cancer (1.2, 1.0 to 1.5) and liver cancer (1.6, 1.2 to 2.2) was significantly increased. For women employed for > 3 months the risk of lung cancer was significantly increased (2.6, 1.5 to 4.3). CONCLUSION: This cohort study shows that bus drivers and tramway employees are at an increased risk of developing several types of cancer. This might be due to the exposure to air pollution during working hours or to other risk factors, primarily smoking.

Adult↗

FOXM1-Specific TCR-Engineered T Cells Target Non-Small Cell Lung Cancer.

FOXM1 is highly expressed in various cancer types and considered a key driver of cancer progression. Accordingly, we evaluated the immunogenicity of FOXM1 and investigated the feasibility of targeting this transcription factor using T-cell receptor (TCR) engineering. We identified epitopes derived from FOXM1 which were immunogenic on HLA-A*02:01, HLA-A*24:02, and HLA-A*23:01, endogenously processed and presented, and resulted in T-cell activation and cytotoxic T-cell responses. Following the generation of TCR-T cells, sensitivity and specificity were confirmed by peptide dose-response and X-scan, respectively. Most importantly, adoptive transfer of TCR-engineered T cells led to a significant reduction in tumor growth, as well as significantly prolonged survival in a tumor-bearing immunocompromised murine model. Our studies confirm the immunogenicity of FOXM1 and feasibility of targeting this antigen using TCR engineering.

Forkhead Box Protein M1↗

Lung cancer in heavy equipment operators and truck drivers with diesel exhaust exposure in the construction industry.

BACKGROUND: Several studies indicate that truck drivers have an increased risk of lung cancer, but few studies have examined lung cancer risk in heavy equipment operators. Workers in both occupations are exposed to diesel exhaust. AIMS: To examine the incidence and mortality from lung cancer among truck drivers and among drivers of heavy vehicles. METHODS: A computerised register of Swedish construction workers participating in health examinations between 1971 and 1992 was used. Male truck drivers (n = 6364) and drivers of heavy construction vehicles (n = 14 364) were selected as index groups; carpenters/electricians constituted the reference group (n = 119 984). RESULTS: Operators of heavy construction equipment experienced no increased risk of lung cancer compared to risk among the carpenter/electrician referents (61 cases v 70.1 expected). However, a significant inverse trend risk with increasing use of cabins was apparent. Truck drivers had increased risks of cancer of the lung (61 cases v 47.3 expected) and prostate (124 cases v 99.7 expected), although only mortality for lung cancer was significantly increased. Comparisons with the general population showed similar results. CONCLUSION: Results are consistent with those of previous studies suggesting that heavy equipment operators with potential exposure to diesel exhaust may have little or no increased risk of lung cancer, although the use of cabins seemed to decrease the risk of lung cancer. The results for truck drivers are also consistent with previous reports of increased lung cancer risk among truck drivers exposed to diesel exhaust, as well as recent reports linking diesel exhaust exposure to prostate cancer.

Aged↗

Lung and bladder cancer among Danish urban bus drivers and tramway employees: a nested case-control study.

BACKGROUND: The combustion of fossil fuels produces small amounts of mutagenic and carcinogenic compounds. We investigated the association between employment and lung and bladder cancer in Danish bus drivers and tramway employees. METHODS: We carried out a nested case-control study of 153 lung and 84 bladder cancer cases, and 606 controls sampled in a cohort of 18 174 bus drivers or tramway employees employed in Copenhagen during the period 1900-1994. The cases and controls or their next of kin were interviewed about smoking, along with occupational and residential history. An exposure index based on which bus routes the bus drivers had mainly been driving was established. Relative risks (RRs) were estimated by conditional logistic regression. RESULTS: The analysis showed decreasing risk for lung cancer with increasing years of employment as a bus driver (RR = 0.97 for each added year, 95% confidence interval = 0.96-0.99). The air pollution index based on main bus for the bus drivers showed no positive correlation with risk.

Adult↗

Cripto monoclonal antibodies.

The success of molecular target-based cancer therapy exampled by Herceptin targeting Her2 indicates that cancer immunotherapy involves identifying and targeting key molecular drivers of cancer. Recently, the human Cripto, a founding member of the epidermal growth factor-Cripto-FRL1-Cryptic (EGF-CFC) protein family has been demonstrated to be a unique molecule and could be targeted by anti-Cripto monoclonal antibodies for the treatment of cancer. Cripto plays an important role in embryonic development, tumorigenesis, cancer cell proliferation and survival. Cripto is upregulated in most epithelial cancers but is absent or weakly expressed in normal cells. Cripto expression is associated with tumorigenesis and invasion. Cripto is also involved in tumor metastasis, which is strongly supported by the recent discovery that the phenotypic changes of increased motility and invasiveness of cancer cells are reminiscent of the epithelial mesenchymal transition (EMT) that occurs during embryonic development. In this review, we emphasize that the EGF-like region of Cripto plays a critical role in Cripto signaling-mediated tumor growth and EMT. Therefore the EGF-like region should be regarded as a therapeutic point for monoclonal antibody (MAb) intervention. The mechanisms of action of these MAbs to the EGF-like region of Cripto are most likely through intervention of c-Src signaling. The CFC region of Cripto is another region to be targeted for treatment of cancer, as the Cripto can bind to activin B through the CFC region to stimulate cell proliferation. The MAbs to the CFC region block the binding of Cripto and activin B and result in an inhibition of cell growth. Therefore the MAbs to Cripto may be of value in the treatment of various cancers.

Animals↗

Statistical analysis of pathogenicity of somatic mutations in cancer.

Recent large-scale sequencing studies have revealed that cancer genomes contain variable numbers of somatic point mutations distributed across many genes. These somatic mutations most likely include passenger mutations that are not cancer causing and pathogenic driver mutations in cancer genes. Establishing a significant presence of driver mutations in such data sets is of biological interest. Whereas current techniques from phylogeny are applicable to large data sets composed of singly mutated samples, recently exemplified with a p53 mutation database, methods for smaller data sets containing individual samples with multiple mutations need to be developed. By constructing distinct models of both the mutation process and selection pressure upon the cancer samples, exact statistical tests to examine this problem are devised. Tests to examine the significance of selection toward missense, nonsense, and splice site mutations are derived, along with tests assessing variation in selection between functional domains. Maximum-likelihood methods facilitate parameter estimation, including levels of selection pressure and minimum numbers of pathogenic mutations. These methods are illustrated with 25 breast cancers screened across the coding sequences of 518 kinase genes, revealing 90 base substitutions in 71 genes. Significant selection pressure upon truncating mutations was established. Furthermore, an estimated minimum of 29.8 mutations were pathogenic.

Amino Acid Sequence↗

STT3A is essential for Wnt signaling and represents a target for cancers driven by RNF43 deficiency.

Abnormalities in the Wnt pathway are major drivers of cancer. RNF43 loss-of-function mutations are frequently detected in aggressive cancers lacking targeted therapies, underscoring the need to uncover key regulators and targets of this pathway. Using a double death trap (DDT) Wnt reporter and genome-wide CRISPR screen, we identified STT3A as an essential regulator of Wnt signaling. Genetic and pharmacological inhibition of STT3A suppressed aberrant Wnt activity caused by RNF43/ZNRF3 loss. Importantly, suppression of STT3A blocked the growth of RNF43-deficient cancer cell lines, patient-derived organoids, and spontaneous tumors. Mechanistically, STT3A regulates Wnt/&#x3b2;-catenin signaling via LRP6, but not LRP5. Glycosylation of LRP6 by STT3A is required for Wnt ligand binding. Notably, STT3A depletion displayed milder effects on bone homeostasis, as supported by phenotypes in STT3A-deficient patients. Together, this study established STT3A as a critical Wnt regulator through LRP6 glycosylation and a therapeutic target for RNF43-deficient cancers.

Humans↗

Molecular determinants of AR-enhancer interaction and cistrome reprogramming in prostate cancer progression.

The androgen receptor (AR) is a key transcription factor in prostate cancer (PCa), whose enhanced and altered functions are known drivers of cancer progression. A key aspect of this is reprogramming of the AR cistrome, which consists of genome-wide enhancer-binding sites through which AR regulates gene expression. The magnitude and biological impact of the AR cistrome are impacted by the AR itself, including the responses to ligand, as well as the organization of the associated DNA response elements, and availability of pioneer factors, cofactors, and noncoding RNAs, all of which contribute to a functional transcription complex. In this review, we will examine, in the context of PCa progression, the factors that affect the binding of AR and its interacting partners at enhancers, with a focus on AR cistrome reprogramming. We also discuss the clinical utility of targeting the AR-enhancer nucleoprotein complex and the potential of using the AR cistrome as a prognostic tool.

Humans↗

The Canadian Labour Force Ten Percent Sample Study. Cancer mortality among men, 1965-1979.

The mortality experience of 415,309 men enrolled in the Canadian Labour Force 10% Sample Study has been updated to the end of 1979. The occupation and industry in which these men were employed between 1965 and 1969 were available, and these records were matched to the Canadian National Mortality Data Base by computerized record linkage. A total of 9,739 deaths from cancer between 1965 and 1979 were identified. Analyses were conducted with respect to men employed in 274 occupations and 294 industries with respect to mortality from 33 different types of cancer resulting in 243 associations in which the 90% lower confidence bound for the relative risk compared to the whole cohort had a value of 1.0 or greater. Based on the criteria of strength of association, dose-response, and consistency, 23 associations were identified as being of particular interest. Of these associations, four (waiters, bartenders and breweries with cancer of the buccal cavity and pharynx, and bartenders with lung cancer) seem most likely to be caused by excess smoking and/or alcohol consumption, and could provide a useful guide for intervention strategies focused on those employed in these occupations. A further seven (carpenters and stomach cancer, clerical occupations and colon cancer, truck drivers, plumbers and pipefitters, sheet metal workers, shipbuilding and repair, and asbestos products manufacturers with lung cancer) have support in terms of biological plausibility and/or other studies in the literature and appear to warrant more intensive study. The third group of associations, although demonstrating strength of association, a dose-response effect, and/or consistency, may well have arisen by chance given the many comparisons made in this study.

Adult↗

Transcriptomic signatures of mind-body transformations therapy in breast cancer: Downregulation of the interferon signaling pathway.

BACKGROUND: Growing evidence has shown that Mind-Body Transformations-Therapies (MBT-T) are able to modulate chronic inflammation, a well-known driver of cancer progression and drug resistance. In our previous work, we showed that a specific MBT-T protocol was able to reduce the release of various pro-inflammatory cytokines and chemokines in the sera of patients with breast cancer that completed adjuvant chemotherapy. Despite these clinical observations, the underlying molecular pathways through which this therapy exerts its effects remain unclear. This study aims to address this gap by characterizing genome-wide transcriptional profiles in patients undergoing a novel MBT-T protocol. METHODS: In this proof-of-concept study, patients with breast cancer were randomized into two groups: Group 1 (CTL), receiving standard follow-up care, and Group 2 (MBT-T), receiving standard follow-up plus biweekly MBT-T for 4 months. Blood samples were collected at different timepoints during the treatment. After RNA extraction from whole blood, gene expression was analyzed on twenty-one patients (CTL, n&#x202f;=&#x202f;7; MBT-T, n&#x202f;=&#x202f;14) using the nCounter&#xae; Human Inflammation Panel (249 genes). RESULTS: Patients undergoing MBT-T showed a significant global downregulation of inflammatory gene expression compared to the control group. The analysis revealed that the Interferon (IFN) signaling pathway was the most significantly suppressed, by downregulation of key genes such as IFIT1, IFIT3, IFI44, MX1 and OASL in the MBT-T group. CONCLUSIONS: MBT-T acts as a biological modulator capable of downregulating key inflammatory pathways at the transcriptional level. These findings provide a genomic basis for the clinical benefits of mind-body interventions in oncology.

Breast cancer↗

[Difference in methylation of genomic DNA between gastric primary cancer and lymph nodes with metastatic gastric cancer].

OBJECTIVE: To investigate the difference in methylation of genomic DNA between gastric primary cancer and lymph nodes with metastatic gastric cancer. METHODS: Methylation CpG island amplification (MCA) was used to enrich the methylated DNA sequences in the cancer tissues and lymph nodes with metastatic gastric cancer resected during operation from 5 patients. Representational difference analysis (RDA) was conducted with the MCA products from the lymph nodes with metastatic gastric cancer as testers and the MCA products of the gastric primary cancer as drivers. The differentially methylated DNA fragments were cloned and sequenced, and underwent similarity analysis by BLAST system. The relationship between the clone sequence and related gene was analyzed by GenBank. Hybridization analysis was performed, using the No 1-3 round RDA products and the MCA products of the tissues of gastric primary cancer and lymph nodes with metastatic gastric cancer with digoxin-labeled KL22 fragment as probe. RESULTS: Nineteen differentially methylated DNA sequences were obtained, distributed at the 5'-end, exon, intron, and 3'-end. KL59 fragment was located in the 9q21, the first exon of p16 gene. KL12 fragment was located in the promoter region of phosphotyrosine phosphatase receptor G (PTPRG) gene. Hybridization signals were obtained for all No 1-3 round RDA products and all testers, but not for the drivers. CONCLUSION: There is a difference in DNA methylation between the tissues of primary cancer and lymph nodes with metastatic gastric cancer. MCA-RNA is an effective method to study the gene methylation. PTPRG gene may be a candidate gene for metastasis of gastric cancer.

Base Sequence↗

Integrative subtyping by bile acid metabolism identifies CLCA1/UGT2A3/ZG16 as markers of immune dysfunction and poor prognosis in colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is the primary driver of cancer-related death and illness across the world. Despite the full-scale shift of the treatment approach for some colorectal cancer patients due to the use of immune checkpoint inhibitors (ICIs), primary resistance still poses a huge challenge to clinicians. Bile acid metabolism is involved in the pathogenesis of CRC. However, its particular function in shaping the tumor immune microenvironment (TIME) and its effect on prognosis and immune treatment response remain unclear. METHODS: Based on the transcriptome and clinical data from The Cancer Genome Atlas-Colon Adenocarcinoma (TCGA-COAD) cohort, we performed unsupervised consensus clustering and classified patients into different molecular subtypes according to bile acid metabolism. We subsequently compared overall survival (OS), immune cell infiltration levels, and differentially expressed genes among the subtypes. In addition, protein-protein interaction (PPI) network and Cox proportional hazards regression were used to identify key hub genes. Finally, the expression of these crucial hub genes was validated in the Gene Expression Omnibus (GEO) cohort and independent clinical patients. RESULTS: The bile-low group showed a significant reduction in OS time (p = 0.0049). The infiltration levels of CD8+ T cells (p < 0.05) and M1 macrophages (p < 0.01) were significantly higher in the bile-low group than in the bile-high group. We identified three key genes-CLCA1, UGT2A3, and ZG16-and found that they all were downregulated in tumor tissues across the TCGA-COAD and GEO datasets, as well as in independent clinical samples. Survival analysis showed that high CLCA1 expression was significantly associated with favorable overall survival (p < 0.001), whereas UGT2A3 (p = 0.23) and ZG16 (p = 0.17) did not reach statistical significance. The three hub genes were negatively correlated with the (TIDE) score (CLCA1: R = - 0.24, p < 0.001; UGT2A3: R = - 0.15, p = 0.0022; ZG16: R = - 0.14, p = 0.0039). CONCLUSION: Our findings suggest that bile acid metabolism could shape the TIME via key genes CLCA1, UGT2A3, and ZG16, and subsequently modify CRC prognosis and immunotherapy responses. These genes may serve as potential prognostic indicators and mechanistic mediators linking bile acid metabolism to T-cell dysfunction, offering insights for future combination strategies targeting the metabolism-barrier-immunity axis.

CLCA1↗

Cancer incidence among male railway engine-drivers and conductors in Sweden, 1976-90.

During recent years, the relationship between exposure to magnetic fields and cancer has attracted increasing interest. In Sweden, train personnel are exposed to comparatively strong magnetic fields in their work. The aim of the present study was to investigate cancer incidence, particularly leukemia and brain tumors, among male railway engine drivers and conductors, respectively, and to compare their cancer incidence with that of the general male population. The study population comprised all male railway engine drivers (n = 7,466) and conductors (n = 2,272) who were ever employed at the Swedish State Railways during the period 1976-90. The study population was observed with regard to cancer incidence by means of the National Cancer Register for the period 1976-90. The total cancer incidence (all tumors included) among railway engine drivers was lower than in the general Swedish population. An increased incidence of lymphocytic leukemia was observed among railway engine drivers and conductors combined (relative risk = 2.3; 95 percent confidence interval = 1.3-3.2), with the same point estimate for both occupational groups. For brain tumor (astrocytoma), the observed relative risk was close to one. The study provides evidence of an excess risk of lymphocytic leukemia in railway engine drivers and conductors, workers with known occupational exposure to magnetic fields.

Adult↗

Endothelial cell-specific DNA methylation alterations in breast cancer.

DNA methylation alterations are well-established contributors to carcinogenesis, yet, in the tumor microenvironment (TME), patterns of lineage and cell-specific methylation alterations are not well understood. Single-cell DNA methylation profiling in the TME is limited by technical challenges and high costs. Here, we use bulk DNA methylation, cell type deconvolution (HiTIMED), and an interaction testing framework (CellDMC) to identify reproducible, computationally inferred lineage-specific epigenetic alterations in the TME supported by orthogonal data sources. Tumor endothelial cells (TECs), critical regulators of angiogenesis, vascular permeability, and immune cell trafficking, acquire structural and functional abnormalities that promote tumor growth. We hypothesize that TECs have altered DNA methylation compared with endothelial cells in non-tumor tissues. In genome-scale methylation data from discovery and validation datasets (tumor n&#x2009;=&#x2009;1071; non-tumor n&#x2009;=&#x2009;415), we identify and validate >4500 TEC-specific CpGs with altered methylation, many mapping to genes involved in angiogenesis and endothelial function. Integration with gene expression data indicates that TEC-specific methylation alterations may reprogram transcriptional networks controlling angiogenesis. High-resolution, cell lineage-specific epigenetic landscapes can be inferred from bulk methylation data, implicating TEC-specific DNA methylation alterations as potential drivers of cancer angiogenesis and vascular dysfunction and providing a framework for future mechanistic and translational studies of the tumor vasculature.

DNA Methylation↗

Critical update and emerging trends in epidermal growth factor receptor targeting in cancer.

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase of the ErbB receptor family that is abnormally activated in many epithelial tumors. The aberrant activation of the EGFR leads to enhanced proliferation and other tumor-promoting activities, which provide a strong rationale to target this receptor family. There are two classes of anti-EGFR agents: monoclonal antibodies (MAbs) directed at the extracellular domain of the receptor and small molecule, adenosine triphosphate-competitive inhibitors of the receptor's tyrosine kinase. Anti-EGFR MAbs have shown antitumor activity in advanced colorectal carcinoma, squamous cell carcinomas of the head and neck, non-small-cell lung cancer (NSCLC) and renal cell carcinomas. The tyrosine kinase inhibitors (TKIs) have a partially different activity profile. They are active against NSCLC, and a specific EGFR inhibitor has shown improvement in survival. Recently, mutations and amplifications of the EGFR gene have been identified in NSCLC and predict for enhanced sensitivity to anti-EGFR TKIs. In addition to specific anti-EGFR TKIs, there are broader acting inhibitors such as dual EGFR HER-2 inhibitors and combined anti-pan-ErbB and antivascular endothelial growth factor receptor inhibitors. Current research efforts are directed at selecting the optimal dose and schedule and identifying predictive factors of response and resistance beyond EGFR gene mutations and/or amplifications. Finally, there is a need for improved strategies to integrate anti-EGFR agents with conventional therapies and to explore combinations with other molecular targeted approaches including other antireceptor therapies, receptor-downstream signaling transduction inhibitors, and targeted approaches interfering with other essential drivers of cancer, such as angiogenesis.

Antibodies, Monoclonal↗

The role of CHAMP1 in chromatin-mediated DNA damage repair.

Defects in the replication stress response are major drivers of cancer development and present key targetable vulnerabilities that can be exploited for anti-cancer therapy. Recent studies have identified CHAMP1 as a novel DNA damage repair factor with roles in double-strand break repair and the replication stress response. Mutations in CHAMP1 are associated with the neurodevelopmental disorder CHAMP1 Syndrome. More recently, children with CHAMP1 Syndrome have developed leukemia, suggesting that CHAMP1 mutations are a potential cancer risk factor. CHAMP1 is part of two DNA damage repair complexes: CHAMP1-POGZ-REV7 (Complex I) and CHAMP1-POGZ-HP1&#x3b1; (Complex II). Complex I promotes homologous recombination by removing the Shieldin complex from the ends of double strand breaks and allowing DSB end resection to occur. Complex II enriches heterochromatin content through the recruitment of the methyltransferase SETDB1 to DNA damage sites. Increased heterochromatin at stalled forks is associated with proper fork stability and restart, demonstrating the importance of CHAMP1 in maintaining genomic integrity. Loss of CHAMP1 leads to increased sensitivity to DNA damaging agents and increased dependence on other DNA damage repair pathways, such as the DNA damage checkpoint and the Fanconi Anemia pathway. CHAMP1 is overexpressed in breast and ovarian cancer cells with high levels of replication stress, providing a molecular mechanism for the tolerance of replication stress. These new findings on the relationship of CHAMP1 with well-established DNA damage repair pathways, suggest that targeting CHAMP1 could present a new synthetic lethality opportunity for cancer cells with high levels of replication stress.

CHAMP1↗

SPHK1 promotes bladder cancer metastasis via PD-L2/c-Src/FAK signaling cascade.

SPHK1 (sphingosine kinase type 1) is characterized as a rate-limiting enzyme in sphingolipid metabolism to phosphorylate sphingosine into sphingosine-1-phosphate (S1P) that can bind to S1P receptors (S1PRs) to initiate several signal transductions leading to cell proliferation and survival of normal cell. Many studies have indicated that SPHK1 is involved in several types of cancer development, however, a little is known in bladder cancer. The TCGA database analysis was utilized for analyzing the clinical relevance of SPHK1 in bladder cancer. Through CRISPR/Cas9 knockout (KO) and constitutive activation (CA) strategies on SPHK1 in the bladder cancer cells, we demonstrated the potential downstream target could be programmed cell death 1 ligand 2 (PD-L2). On the other hand, we demonstrated that FDA-approved SPHK1 inhibitor Gilenya&#xae; (FTY720) can successfully suppress bladder cancer metastasis by in vitro and in vivo approaches. This finding indicated that SPHK1 as a potent therapeutic target for metastatic bladder cancer by dissecting the mechanism of action, SPHK1/S1P-elicited Akt/&#x3b2;-catenin activation promoted the induction of PD-L2 that is a downstream effector in facilitating bladder cancer invasion and migration. Notably, PD-L2 interacted with c-Src that further activates FAK. Here, we unveil the clinical relevance of SPHK1 in bladder cancer progression and the driver role in bladder cancer metastasis. Moreover, we demonstrated the inhibitory effect of FDA-approved SPHK1 inhibitor FTY720 on bladder cancer metastasis from both in vitro and in vivo models.

Urinary Bladder Neoplasms↗

G-quadruplex structures as regulators of cellular processes and drivers of genome instability in cancer.

G-quadruplexes (G4s) are essential regulatory structures whose biological functions are inseparable from their potential to destabilize the genome. They play critical roles in transcription, replication and chromatin architecture, yet they also contribute to the genomic instability that fuels cancer. This dual role is an inherent consequence of where G4s form in the genome. G4s are enriched at highly active regulatory regions, including promoters, replication origins and topologically associated domain boundaries, where their controlled formation and resolution by helicases and topoisomerases support normal genome function. When this control is lost, the same features that make G4s functional become harmful, leading to R-loop and G-loop accumulation, replication fork stalling and increased conflicts between transcription and replication. Topoisomerase activity, which normally relieves supercoiling stress, can instead generate the DNA double-strand breaks that characterize cancer genomes. Persistent G4 structures also promote micronuclei formation and cytoplasmic DNA accumulation, activating the cGAS-STING innate immune signaling pathway. Here, we discuss these mechanisms and present pan-cancer genomic analyses showing that these processes operate broadly across human tumors. Therapeutically targeting G4s requires balancing their essential regulatory roles with their pathological effects. Understanding this tension is therefore essential for exploiting G4s as therapeutic targets across cancer types.

DEAH-box helicases↗