DNA Methylation Analysis Research Articles

Abstract 4627: Metastatic renal cell carcinoma with occult primary: Clinical and biological evidence for a new entity of cancers of unknown primary that beneficiates from tissue-tailored treatment

Abstract Background: Cancers of unknown primary (CUP) is a heterogenous group of malignancies characterized by distant metastases in the absence of detectable primary. Specifics subgroups of CUP that share similarities with cancers of known primary beneficiate from tissue-tailored therapeutic strategies. The objective of this study was to characterize the clinical and biological presentation of a cohort of patients with suspected CUP of renal origin (rCUP) and to evaluate their optimal therapeutic management. Methods: All Patients with rCUP identified prospectively between 2020 and 2023 within the French National Multidisciplinary Tumor Board for CUP were included. Centralized pathological review and immunohistochemical stainings were performed. Whole Exome Sequencing (WES), whole transcriptomic sequencing (RNAseq) and application of the deep-learning based algorithm TransCUPtomics for prediction of tissue of origin, and DNA methylation analysis were performed and compared to public renal cell carcinomas (RCC). Progression Free Survival (PFS) and Overall Survival (OS) were calculated using Kaplan-Meier estimates. Results: 23 patients were included. The median age at diagnosis was 57 yo and 17/23 were male. The most common metastatic sites were the bones (N=17) and the lymph nodes (N=14). 19/23 patients presented with at least two distinct distant metastatic sites. Genomic analyses performed in 10 patients led to the identification of recurrent inactivating mutations in genes commonly altered in RCC, including NF2 (N=7), SETD2 (N=3), or VHL (N=1). 10/11 samples analyzed by RNAseq were predicted as RCC by the TransCUPtomics classifier based on their gene expression profiles. DNA methylation profiling performed in 7 samples showed major similarity with known RCC subtypes.Centralized pathological review and integration of molecular characteristics led to the final diagnoses of papillary RCC (N=2), clear cell RCC (N=7), renal medullary carcinoma (N=1), TFEB-amplified RCC (N=1) and unclassified RCC (N=12). 20/23 patients received at least one line of systemic treatment based on the renal origin, including anti-angiogenic TKI, anti-PD1/PDL1 antibody, anti-CTLA4 antibody or mTOR inhibitor. The median PFS under the first renal-oriented systemic treatment was 5 months and 10 patients remained progression-free for more than 6 months under tailored-treatment. The median OS was 31 months, and 11 patients are still alive in October 2023. Conclusions: This study shows that rCUP represent a new entity within CUPs that shares major similarities with classical RCC despite the more frequent presentation of unfavorable prognostic factors. Prolonged survival can be observed with renal-tailored systemic treatment, supporting the individualization of these patients within CUP. Citation Format: Nicolas Jacquin, Julien Masliah-Planchon, Guillaume Grisay, Ronan Flippot, Riwan Brillet, Célia Dupain, Maud Kamal, Isabelle Guillou, Nadège Gruel, Nicolas Servant, Pierre Gestraud, Jennifer Wong, Vincent Cockenpot, Andreia Goncalves, Janick Selves, Hélène Blons, Etienne Rouleau, Oliver Delattre, Christophe Le Tourneau, Ivan Bièche, Yves Allory, Laurence Albigès, Sarah Watson. Metastatic renal cell carcinoma with occult primary: Clinical and biological evidence for a new entity of cancers of unknown primary that beneficiates from tissue-tailored treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4627.

Abstract 1029: Role of PCDHGA12/PRRX1 methylation for the diagnosis of lung cancer using bronchial washing fluid

Abstract Bronchoscopy is a frequently used initial diagnostic procedure for patients with suspected lung cancer (LC). Cytological examinations of bronchial washing (BW) samples, obtained during bronchoscopy, often yield inconclusive results in the diagnosis of LC. Aberrant DNA methylation has previously been shown to be a useful biomarker for LC. DNA methylation analysis in BW specimens could serve as a valuable clinical adjunct to cytology. In this study, to identify potential methylation biomarkers for LC, methylation microarray analyses were performed on primary tumors and compared with adjacent non-tumor tissues of 13 patients with LC at various stages (I - IV). A stepwise validation process using bisulfite-pyrosequencing of cell lines and tissues identified six methylated genes (ADAMTS20, FOXC2, NKX2-5, OLIG3, PCDHGA12, and PRRX1) associated with LC. To assess methylation in BW samples, a highly sensitive and accurate 3-plex Linear Target Enrichment (LTE)-quantitative methylation-specific PCR (qMSP) in a single closed tube was developed. Clinical validation was performed using BW samples from patients with LC (n = 68) and non-LC (benign) (n = 33) and identified PCDHGA12 and PRRX1 methylation as the best performing marker combination for detecting LC. The 2-marker combination exhibited a sensitivity of 82.4% and a specificity of 87.9%, with an area under the curve of 0.891. Notably, its sensitivity was 100% for small cell LC. The 2-marker combination had a positive predictive value of 93.3% and a negative predictive value of 70.7%. Its sensitivity outperformed cytology. The methylation status of the 2-marker showed no correlation with gender, age or stage, but was associated with tumor location and histology. In conclusion, we identified PCDHGA12 and PRRX1 methylation as high potential biomarkers for LC diagnosis. This study shows that these biomarkers could be used as a diagnostic adjunct to cytology in the clinical practice for diagnosing LC in BW specimens. Citation Format: Ji Woong Son, Tae Jeong Oh, Minheyok Lee, Chang Ryul Park, Sungwhan An. Role of PCDHGA12/PRRX1 methylation for the diagnosis of lung cancer using bronchial washing fluid [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1029.

Abstract 155: Clinico-radiological and histomolecular analyses identify of a new subtype of diffuse midline glioma, H3 K27 and BRAF/FGFR1 co-altered

Abstract Diffuse midline gliomas (DMG) H3 K27-altered are incurable grade 4 gliomas and represent a major challenge in neuro-oncology. This tumor type is now classified in four subtypes by the 2021 edition of the WHO Classification of the Central Nervous System (CNS) tumors. However, the H3.3-K27M subgroup still appears clinically and molecularly heterogenous. Recent publications reported that rare patients presenting a co-occurrence of H3.3K27M with BRAF or FGFR1 alterations tended to have a better prognosis. To better study the role of these co-driver alterations, we assembled a large pediatric and adult cohort of 29 tumors H3K27-altered with co-occurring activating mutation in BRAF or FGFR1 as well as 31 previous cases from the literature. We performed a comprehensive histological, radiological, genomic, transcriptomic and DNA methylation analysis. Interestingly, unsupervised t-distributed Stochastic Neighbor Embedding (tSNE) analysis of DNA methylation profiles regrouped BRAFV600E and all but one FGFR1MUT DMG in a unique methylation cluster, distinct from the other DMG subgroups and also from ganglioglioma (GG) or high-grade astrocytoma with piloid features (HGAP). This new DMG subtype harbors atypical radiological and histopathological profiles with calcification and/or a solid tumor component both for BRAFV600E and FGFR1MUT cases. Contrary to other DMG, these tumors occur more frequently in the thalamus (70% for BRAFV600E and 58% for FGFR1MUT) and patients have a longer overall survival with a median above three years. The analyses of a H3.3-K27M BRAFV600E tumor at diagnosis and corresponding in vitro cellular model showed that mutation in H3-3A was the first event in the oncogenesis, indicating a distinct oncogenesis from classical DMG despite an identical founder H3K27 alteration, and possible subclonal evolution.In conclusion, DMG, H3 K27 and BRAF/FGFR1 co-altered represent a new subtype of DMG with distinct genotype-phenotype characteristics, which deserve further attention with respect to trial interpretation and patient management. Our work also lays the foundations for therapeutic development highly-needed against this deadly disease. Citation Format: Lucie Auffret, Yassine Ajlil, Arnault Tauziede-Espariat, Thomas Kergrohen, Chloé Puiseux, Laurent Riffaud, Pascale Blouin, Anne-Isabelle Bertozzi, Pierre Leblond, Klas Blomgren, Sebastien Froelich, Alberto Picca, Mehdi Touat, Marc Sanson, Kevin Beccaria, Thomas Blauwblomme, Volodia Dangouloff-Ros, Nathalie Boddaert, Pascale Varlet, Marie-Anne Debily, Jacques Grill, David Castel. Clinico-radiological and histomolecular analyses identify of a new subtype of diffuse midline glioma, H3 K27 and BRAF/FGFR1 co-altered [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 155.

Abstract 3439: Factors affecting the performance of existing epigenetic clocks to predict chronological age in colorectal tumor and normal tissues

Abstract Epigenetic age (EA) may serve as a risk stratification biomarker for early-onset colorectal cancer (EOCRC, <50 years old), which has been rising substantially in recent decades. We utilized publicly available data in a descriptive analysis to compare epigenetic clocks in colorectal tissue and to investigate differences between chronological age (CA) and biological age, as measured by EA, in relation to demographic and clinical features. We analyzed DNA methylation (DNAm) array data on 144 participants (96 CRC cases, 48 healthy controls) from the Colonomics Study (CLX; Barcelona, Spain) and 331 CRC cases (51 EOCRC, 316 average-onset (≥50) colorectal cancer (AOCRC)) from The Cancer Genome Atlas (TCGA) as well as corresponding demographic and clinical variables. Among CLX participants, the 96 CRC cases provided colon tumor and paired normal mucosa samples, while the 48 controls provided healthy colon mucosa samples. TCGA included primary tumor samples from 331 cases with colon or rectal adenocarcinoma (TCGA-COADREAD). The 2013 Horvath clock estimated EA based on CA, while epiTOC, estimated the relative stem cell division rate from tissue biospecimens. We examined the correlations between CA and EA stratified by case/control status, sample type, sex, and age of onset (TCGA only). Tissue from CLX controls demonstrated a strong, positive correlation (r>0.9) between CA and EA for both the 2013 Horvath and epiTOC clocks. Using the Horvath clock, CA and EA correlations in normal mucosa and tumor tissue samples from CLX varied, with r = 0.74 and r = 0.41, respectively, and were weaker using the epiTOC clock, with r = 0.26 (normal) and r = 0.10 (tumor). When CLX cases were stratified by sex, the CA and EA (Horvath) correlations among female cases were r = 0.80 (normal) and r = -0.12 (tumor), while the correlations for males were stronger at r = 0.58 (normal) and r = 0.31 (tumor). This is in comparison to the epiTOC clock with females showing correlations of r = -0.02 (normal) and r = 0.41 (tumor), while males had r = 0.06 (normal) and r = 0.11 (tumor). In TCGA, correlations for EOCRC were r = -0.20 (Horvath) and r = -0.08 (epiTOC) and for AOCRC were r = 0.29 and 0.20, respectively. By sex, correlations for females with EOCRC for Horvath and epiTOC were r = -0.09 and r = -0.07, respectively, while correlations for males with EOCRC were r = -0.02 and r = -0.08, respectively. For TCGA cases with AOCRC, the correlations between CA and EA were r = 0.35 and r = 0.22 for females, and r = 0.26 and r = 0.20 for males, respectively for Horvath and epiTOC. This study revealed substantial variability in the ability of existing epigenetic clocks to accurately predict chronological age, with tissue type and sex strongly influencing the resulting correlations. Our findings highlight the importance of considering these factors when choosing an epigenetic clock. Citation Format: Christopher L. Benson, Ferran Moratalla-Navarro, Anna Diez-Villanueva, Matthew A. Devall, Victor Moreno, Stephanie L. Schmit, Fredrick R. Schumacher. Factors affecting the performance of existing epigenetic clocks to predict chronological age in colorectal tumor and normal tissues [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3439.

Abstract 7004: DNA Methylation analysis of African American colorectal cancers reveal race-specific alterations

Abstract African Americans (AAs) have among the highest incidence and mortality rates of colorectal cancer (CRC) in the US. They present with more right-sided, microsatellite stable (MSS) tumors and are diagnosed at earlier ages than non-Hispanic Whites (NHW). While DNA methylation changes and their significance have been previously described in CRC, much less is known about the unique DNA methylation changes that occur in AA CRCs compared to NHW CRCs. In the current study, we analyzed DNA methylation changes in AA patients and compared those changes to data from NHWs. AA patients diagnosed with a MSS colorectal tumor at the Yale New Health System were included in the study. A pathologist reviewed archival slides, and selected areas from CRCs (n=160) and adjacent normal tissue (n=42) were cored (median age=59; 82 females, 78 males). DNA was bisulfite converted and analysis performed using EPIC arrays. The 450K methylation array from NHW CRCs was also analyzed for 217 CRCs and 20 normal tissues obtained from TCGA (median age=68; 103 females, 114 males). Differentially methylated regions (DMRs) with |Δβ|>0.1, FDR corrected p-value <0.05 between tumor and normal tissue were identified using SeSAMe. We identified 4881 DMRs (57% hyper- and 44% hypomethylated) between AA CRC and normal tissue. Of these, 46% were in CpG Islands, 15% in CpG Shores, 4% in CpG shelves, and 36% in open sea. Most DMRs (71%) were in promoter regions, with 18% in gene bodies, 5% in enhancer regions, and 6% in intergenic regions. Next, we performed additional DMR analysis using overlapping probes from both arrays to compare NHW with AA data. We identified 2239 DMRs between AA CRC and normal tissue compared to 4138 in NHW. Of the 2239 AA DMRs, 1419 (66%) were common with NHW DMRs, 790 (34%) were unique to AAs. There were many overlapping pathways and genes; however, the DMRs impacting these pathways differed between AA and NHW CRCs. Hypermethylation of LCK, a tyrosine kinase involved in T-cell receptor signaling, was found in 60% of AA CRCs compared to 5.9% of NHW CRCs. LCK hypermethylation leads to CD4/8 T-cell inactivation and linked to poor outcomes in lung cancer. We observed AA-specific hypermethylation of SSTR1 in 57.2% of AA CRCs compared to 27.6% of NHW CRCs. Somatostasin (SST) suppresses tumor growth by regulating certain factors involved in cell proliferation. Hypermethylation of SSTR1 has been associated with various malignancies including gastric cancer. Lastly, promoter hypermethylation of 3 protocadherin genes was found in 65.1% of AAs compared to 33.1% NHWs. Protocadherins regulate WNT signaling and hypermethylation is associated with poor outcomes in multiple cancers. Taken together, these results show AA-specific CRC methylation changes compared with NHW CRCs. Further work is warranted to investigate the potential functional and clinical implications of these methylation alterations, some of which may represent therapeutic targets and biomarkers. Citation Format: Seeta Rajpara, David N. Buckley, Rosa Xicola, Reger Mikaeel, Mary K. Yagle, Baris Kerimoglu, Curtis Thorne, Dante A. Bellomo, Megha Padi, Xavier Llor, Nathan Ellis, Bodour Salhia. DNA Methylation analysis of African American colorectal cancers reveal race-specific alterations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7004.

Abstract 7030: Reference materials for analysis of DNA methylation in cell-free circulating tumor DNA

Abstract Aberrant DNA methylation is associated with many cancers including breast, liver, bone, and colon and has been identified as a biomarker for early cancer screening. Liquid biopsies are beginning to screen for DNA methylation in cancer-derived DNA, but accurate assessment of methylation is not trivial, and methods like bisulfite sequencing can result in biased data. Reference materials for establishing the analytical validity of measurements of CpG methylation are not widely available. In order to prepare such reference materials, genomic DNA (gDNA) was extracted from the well characterized human reference cell line GM24385 and fragmented to a circulating tumor DNA (ctDNA)-like size distribution. This DNA was processed further to prepare CpG-methylated and unmethylated versions. The size distribution was determined by using the Bioanalyzer High Sensitivity DNA Kit (Agilent, Santa Clara, CA). Methylation status in the reference materials was confirmed by both digital PCR (dPCR) and NGS based methods. A digital PCR method was developed to analyze heterozygous single nucleotide polymorphisms (SNPs) using the Bio-Rad QX200™ Droplet Digital PCR (ddPCR) System. To determine methylation levels by NGS, the NEBNext™ Enzymatic Methyl-seq Kit was used (EM-seq). Paired-end sequencing of the libraries was performed on a NextSeq™ 2000 (Illumina, San Diego, CA). Data alignment to hg19 was done with the bwa-meth (Pedersen, BS., et al.) aligner, and assessment of methylation in the aligned data was done with MethylDackel (Ryan, D.). Each reference material had an average peak size of ~160 bp in length, similar to patient cfDNA. By dPCR, the unmethylated reference material had an average of 0.73% DNA methylation, while the methylated reference material had an average of 100.10% DNA methylation. Values can be above 100% by dPCR due to unequal representation of both alleles. By NGS, the unmethylated reference material had an average of 0.93 % CpG methylation, which was similar to the background of 1.13 % and 1.31 % for CHG and CHH methylation, respectively. The methylated reference material had an average of 93.95 % CpG methylation, with a background of 0.69 % and 0.74 % for CHG and CHH methylation, respectively. Because EM-seq relies on enzymatic protection and conversion steps, it may be that these reactions did not allow for full protection and full conversion, which led to values above 0 % for unmethylated and below 100 % for methylated materials. We have developed reference materials for the assessment of DNA methylation in ctDNA. One unmethylated and one methylated reference material was created. These reference materials can be mixed together to the level of methylation required to help aid in assay design, optimization, and validation. Citation Format: Alysha Higgs, Angelique Ryan, Jayanthi Ramprakash, Dana Ruminski Lowe, Yves Konigshofer, Catherine Huang, Andrew Anfora, Russell Garlick, Bharathi Anekella. Reference materials for analysis of DNA methylation in cell-free circulating tumor DNA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7030.

Abstract 5106: Pharmacological targeting of LSD1 prolongs animal survival times in patient derived orthotopic xenograft models of posterior fossa ependymoma in combination with fractionated radiation

Abstract Background: Posterior Fossa Group A Ependymoma (PFA EPN) constitute one of the most aggressive and highly recurrent molecular subtypes of childhood Ependymomas. We recently performed a comprehensive genome-wide DNA methylation analysis in recurrent pediatric EPN tumors from patients that were followed up for over 13 years. Integrative analysis between tumor DNA methylation and histone modification identified LSD1 as a druggable driver of PFA EPN recurrence. In this study, we examined the therapeutic efficacy of our newly developed LSD1 inhibitor SYC-836 in PDOX models of recurrent PFA EPN. Methodology: To determine the in vitro anti-tumor activities of SYC-836, paired PFA EPN xenograft cell cultures (monolayer and 3D neurospheres) were treated with SYC-836 at 8 concentrations (0.02-25 µM) and examined for changes of cell proliferation every 3-4 days through day 14. To validate the drug’s in vivo efficacy, two established posterior fossa EPN PDOX models, ICb-4423EPN and ICb-2002EPN, were utilized. Forty 8-week old SCID mice of both genders received intra-cerebellar tumor cell implantation and were divided into 4 treatment groups (n=10 per group): 1) control, 2) radiation (2 Gy/day x 5 days), 3) SYC-836 (15 mg/kg, daily intra-peritoneal injection for 28 days), and 4) combination (radiation + SYC-836). Animal survival times were analyzed using log-rank analysis. Changes in LSD1 protein expression and histone lysine methylation were examined through western hybridization. Results: SYC-836 strongly suppressed PFA EPN cell growth in vitro, in both, a time- and dose-dependent manner. While there was no survival benefit with either SYC-836 only (P=0.186) or XRT only (P=0.205); combining SYC-836 with XRT significantly (P=0.04) prolonged the median survival time of ICb-4423EPN, from 46 days in the untreated group to 59 days; and in ICb-2002EPN, even more prominent, from 136 days to 180 days (P=0.007). SYC-836 was well tolerated in mice with no loss of body weight or other toxicities. Changes in LSD1 protein expression and H3K4me2 were detected through western hybridization during and after SYC-836 treatment. Conclusion: Our data support LSD1 as a druggable driver of PFA recurrence and highlights strong anti-tumor activities of SYC-836 in combination with radiation, a standard therapy of pediatric EPN. SYC-836 may have a role in the clinical setting by either reducing radiation dosages or be an adjuvant agent to other chemotherapy drugs in our treatment approach for ependymoma. Citation Format: Milagros M. Suarez Palacios, Sibo Zhao, Huiyuan Zhang, Lin Qi, Holly Lindsay, Mari Kogiso, Frank Braun, Adekunle M. Adesina, Yuchen Du, Yongcheng Song, Xiao-Nan Li. Pharmacological targeting of LSD1 prolongs animal survival times in patient derived orthotopic xenograft models of posterior fossa ependymoma in combination with fractionated radiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5106.

Abstract 2163: Socioeconomic status associates with epigenetic modulation of TET2: An emerging pathway in cardio-oncology

Abstract Introduction: Adverse social determinants of health (SDOH) are known to accelerate poor outcomes in cardiovascular disease (CVD) and cancer. Clonal Hematopoiesis (CH) is a mechanism implicated in these disease states, partially driven by epigenetic regulatory genes, including TET2. Yet, there is not much known about how epigenetic modulations of TET2 itself may relate to the immune system and subsequent disease development. Hypothesis: We hypothesize that socioeconomic status (SES), as a SDOH marker, relates to epigenetic modulation of TET2. Methods: 60 African American adults (93.3% female, mean age 61) with CVD risk, living in the Washington, D.C. area self-reported their SES as household income. Immune system activity was assessed via splenic activity (SpleenA) by 18FDG PET/CT. Serum cytokine levels were measured by ELISA and DNA methylation analysis evaluated the epigenetic modulations of TET2. Multivariable regression analysis adjusted for ASCVD 10-year risk score and BMI was used to examine associations. Results: Out of 33 TET2 methylation sites, we found 3 sites that were significantly related to SES. Notably, only Tet2cg09666717 (SES β=0.310, p=0.038) was also associated with SpleenA (β=-0.453, p=0.036) and several cytokines: IL-17A, IL-1β and TNFα along with trending to significance with IFN-γ (Table). Conclusion: Thus, we found that SES associates with hypomethylation of Tet2cg09666717, which further related to SpleenA and inflammatory markers. Our findings are hypothesis generating and suggest that lower SES may relate to inflammation and immune system dysregulation by the way of epigenetic modulation of TET2. These results should be examined in larger, functional studies with diverse population-based cohorts to determine the potential relationships of both SDOH and epigenetic markers in CH and cardio-oncology outcomes. Associations between TET2 methylation sites, SpleenA, SES and Cytokines in DCCNHA cohort, 2014-17 Tet2cg09666717 Tet2cg05094833 Tet2cg10594473 SES 0.310 (0.038) -0.405 (0.006) -0.283 (0.060) Splenic Activity -0.453 (0.036) 0.004 (0.985) 0.097 (0.654) IL-6 -0.078 (0.558) -0.211 (0.108) -0.222 (0.084) IL-8 -0.199 (0.153) 0.024 (0.865) -0.004 (0.979) IL-17A -0.373 (0.010) 0.134 (0.370) -0.434 (0.017) IL-1β -0.382 (0.003) 0.042 (0.757) -0.143 (0.275) TNFα -0.456 (0.000) -0.157 (0.244) 0.005 (0.969) IFN-γ -0.258 (0.062) -0.037 (0.790) 0.022 (0.876) Data are presented as standardized β coefficient (p-value). All data are adjusted for 10-year predicted ASCVD risk and BMI; ASCVD = atherosclerotic cardiovascular disease; BMI = body mass index; IL-6 = interleukin 6; IL-8 = interleukin 8; IL-17A = interleukin 17A; IL-1β = interleukin 1 beta; TNFα = tumor necrosis factor; IFN-γ = interferon gamma Citation Format: Sonal Sharda, Yvonne Baumer, Alina P. Pang, Abhinav Saurabh, Billy S. Collins, Valerie M. Mitchell, Michael J. Corley, Tiffany M. Powell-Wiley. Socioeconomic status associates with epigenetic modulation of TET2: An emerging pathway in cardio-oncology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2163.

Abstract 2424: Detection of prostate cancer in urine by fragment-level DNA methylation analysis

Abstract Introduction: Screening for prostate cancer (PCa) with molecular markers is hindered by low tumor allele fraction (TAF) in liquid biopsy samples such as blood or urine. Others have suggested that tumor allele enrichment can be achieved by evaluating fragment-level methylation patterns generated by next generation sequencing (NGS). Here, we test this concept using target capture NGS on cfDNA from prediagnostic collected urine samples to discriminate PCa from otherwise healthy men. Methods: Buffered urines were collected from 23 patients with biopsy confirmed PCa (Gleason score 6-9) and 24 otherwise healthy age matched cancer-free controls. cfDNA was isolated and enzymatic methyl-seq libraries were prepared and enriched by hybrid capture using probes mapping to 197 differentially methylated regions (DMRs) from a previous PCa/normal tissue marker discovery study in our lab. These DMRs were subsequently vetted independently using a methylome-wide dataset from a cohort of 36 clean and disease control urines to ensure low non-cancer background signal (<1%). Indexed libraries were sequenced at 560X deduplicated coverage and fragment-level CpG methylation information was extracted from individual sample .bam files. Mapped sequencing reads exhibiting concordant methylation were used to derive a quantitative α-score. Reads had to contain at minimum 5 CpGs and have an α-value (% 5mC per read) > 60%. Positivity for the 197 markers required an α-score greater than 6 sigma (σ) above the mean of the control arm. Values were variance-adjusted to ensure equal weighting. Beta (β) analysis (mean % 5mC across all reads) of the data was also performed for comparison. Results: Of the 197 markers, 187 were positive for one or more PCa patients. Tumor-derived fragments were detected in 22 of 23 cases, which included 8 G-6, 9 G-7, 2 G-8, and 3 G-9 patients. 1 G-7 was missed, however the sequencing coverage for this sample was significantly lower than the others due to poor library enrichment. 2 of the 24 healthy controls were positive, one with extremely high fragment counts. Upon re-review of the full control cohort, this patient had been diagnosed with bladder cancer 2 years after urine collection. The 2nd patient had was diagnosed with lung cancer in a similar timeframe. The other 22 confirmed cancer-free controls had α-scores below the 6σ threshold. Using a co-captured reference gene (B3GALT6) to mimic genomic equivalents, the TAFs ranged from 0.015% to 8%. β analysis of the data detected only 13 PCa patients (>6σ) and marker positivity was lower than the fragment-level approach. Conclusion: Target capture NGS coupled with fragment-level analysis is a rational approach for sensitive and specific detection of low tumor-derived DNA in liquid biopsy samples. For PCa assay in urine, we were able to uncover positivity in cancer patients approaching 1 in 10,000 ctDNA dilution levels. These results warrant further validation studies with this and other cancers. Citation Format: Tibor Bedekovics, William R. Taylor, Zhifu Sun, Saurabh Baheti, Xiaoming Cao, Kelli N. Burger, Karen A. Doering, Patrick H. Foote, Benjamin Gochanour, Douglas, W. Mahoney, Matthew T. Gettman, John B. Kisiel. Detection of prostate cancer in urine by fragment-level DNA methylation analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2424.

Abstract 1463: Characterizing inflammation-induced epigenetic and transcriptomic alterations driving NSCLC using lung organoid models

Abstract Chronic inflammation is a major driver of lung cancer and contributes to its pathogenesis by inducing genetic and epigenetic alterations. These, in turn, modulate the microenvironment to facilitate emergence of tumor promoting immune evasive mechanisms. The evolution of epigenetic events and their role, both alone, and in association with lung cancer specific genetic drivers in initiation of lung cancer is not well delineated. Specific pathological subtypes of non-small cell lung cancer (NSCLC) have distinct cells of origin, suggestive of cell type-specific changes in driving their development. We employed lung organoid models with chronic exposure to cigarette smoke condensate (CSC) to elucidate sequential, cell type-specific epigenetic and transcriptomic alterations and their role in co-operating with genetic events to drive development of NSCLC. We examined epigenomic and transcriptomic alterations over a 6-month exposure period by DNA methylation arrays, ATAC-seq, and RNA-seq. We observe that CSC exposure causes distinct morphological changes in organoid structure and composition, accompanied by an increase in proliferative potential. Using flow cytometry and immunofluorescent staining approaches, we demonstrate a chronic inflammation-driven shift in stem cell populations accompanied by reduction in differentiated cell types. Bulk and single-cell RNA sequencing approaches identified distinct temporal changes in transcriptional signatures in CSC exposed organoids suggestive of evolution of an immune evasive and pro-tumorigenic phenotype. Gene set enrichment analysis revealed a downregulation of interferon signaling and upregulation of Myc targets and oxidative phosphorylation pathways in CSC treated organoids. Notably, co-culturing organoids with key immune cell populations, demonstrate the ability of the CSC exposed organoids to modulate shifts in immune cells from a pro- to anti- inflammatory state. In accordance with this shift in immune cell phenotype, CSC treated organoids secreted decreased levels of pro-inflammatory cytokines as measured by multiplex ELISA assays. Genome wide DNA methylation analysis reveal that CSC methylated genes were associated with differentiation and cell fate commitment as well as transcription factor activity. Finally, we demonstrate that introduction of key NSCLC-specific driver events at the 6-month time point sensitize only CSC treated organoids to tumor formation in vivo, leading to the development of distinct genetic driver-specific subtypes of NSCLC. Altogether, our results demonstrate the ability of chronic inflammation to drive key cell type-specific transcriptomic and epigenetic changes leading to the development of distinct subtypes of NSCLC. Our findings will help identify molecular correlates for early detection and aid development of novel therapeutic strategies for disease interception. Citation Format: Na Wang, Kara Lombardo, Raksha Padaki, Ray-Whay Chiu Yen, Malcolm V. Brock, Leslie Cope, Hariharan Easwaran, Stephen B. Baylin, Michelle Vaz. Characterizing inflammation-induced epigenetic and transcriptomic alterations driving NSCLC using lung organoid models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1463.

Abstract 7009: Quantification of DNA methylation using methylation-sensitive restriction enzymes and digital PCR

Abstract DNA methylation is a common epigenetic modification, characterized by the presence of the signature 5-methylcytosine without altering the sequence of DNA. The study of DNA methylation in mammals has gained significant attention due to its broad impact on numerous biological processes and its critical role in the onset and progression of many diseases, such as cancer and aging. Consequently, there is a pressing need for a rapid and precise method to assess methylation status. Currently, most approaches for quantifying DNA methylation rely on sodium bisulfite treatment. However, such approaches do not align with the uracil DNA glycosylase PCR system. In this study, we demonstrate the application of methylation-sensitive restriction enzymes (MSRE) and digital PCR to determine the methylation status of the Ras association domain family 1 isoform A (RASSF1A) in cancer cell lines. Digital PCR enables the precise detection and absolute quantification without the reliance on reference standards. We developed a multiplex digital PCR assay that includes the target gene RASSF1A, along with two reference genes for the purpose of monitoring digestion completion and correcting DNA input. Each sample of interest was measured both before and after a MSRE digestion. To ensure the quantification accuracy, we employed the commercially available CpGenome human methylated DNA standard with a known concentration from MilliporeSigma, treating it with and without a MSRE, and subsequently performing digital PCR experiments using Roche Digital LightCycler® IVD system with a Universal nanowell plate featuring 28,000 partitions. The expected concentrations lay within the 95% confidence interval, affirming the accurate quantification achieved through digital PCR. Next, we measured the fraction of methylated alleles in various lung cancer and breast cancer cell lines, as well as in healthy human gDNA. The methylation of RASSF1A promoter in healthy human gDNA is ~0.7%, while a broad range of methylation levels was observed in cancer cell lines, ranging from ~0.7% to ~100.2%. Notably, the influence of GC bias was identified in this study. To overcome this critical challenge, we optimized the usage of several high GC enhancers. The results demonstrated that the concentration of 5-7.5% DMSO, 7.5% glycerol, and commercially available OneTaq or Q5 GC enhancers from New England Biolabs were effectively incorporated into the Roche digital PCR system, thereby enhancing the accuracy of quantification from 30% to 100%. Together, we demonstrated a remarkable approach for DNA methylation analysis using Roche digital PCR system in combination with MSREs and suitable high GC enhancers. This study suggests a promising rapid, accurate and cost-effective tool to advance research in the field. *Data on file at Roche Diagnostics, Wilmington, MA, USA Citation Format: Yu Zhao, Lindsey Cambria. Quantification of DNA methylation using methylation-sensitive restriction enzymes and digital PCR [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7009.

Abstract 7288: Evaluation of silica spin-column and bead formats for rapid promoter DNA methylation analysis by qMSP in clinical and point-of-care settings

Abstract Late-stage cancers often lack effective management and treatment options, emphasizing the importance of early diagnosis for better prognosis and lower mortality rates. Molecular markers, such as DNA methylation tests, have shown promise in predicting and detecting cancer at its earliest stages. The COVID-19 post-pandemic scenario is providing a one in one-hundred-year opportunity of utilizing the excess installed PCR capacity world-wide to develop novel Quantitative Methylation Specific PCR (qMSP) screening strategies for cervical cancer screening in low-resource settings. This study aimed to compare the use of commercial bisulfite conversion kits in cervical epithelium liquid cytology samples (liquid cytology) from cancer screening clinics in the United States. Commercially available rapid bisulfite conversion protocols using silica spin column and magnetic beads were compared with conventional DNA extraction followed by bisulfite conversion protocols to profile DNA methylation by qMSP in a panel of methylated genes we previously developed to distinguish normal and cervical cancer patient samples. The results revealed that small sample volumes are suitable for methylation studies. Comparisons among four spin-column kits showed no significant differences in β-actin Cycle Threshold (Cts) values between Abcam, Epigentek, QIAGEN and Zymo D5021 kits. Zymo The best performing spin-column kit was compared with manual and automated versions of magnetic bead kits using a 96-well plate format for higher throughput. Methylation profiling of three genes (β-actin ZNF516, and FKBP6) with manual and automated magnetic bead kits revealed that automation increases throughput without a reduction in amplification efficiency in open PCR systems. Cost analysis showed that the direct kits 96-well plate format were more affordable compared to the Gold Standard manual protocol that uses spin-columns. An optimized version of Zymo D5046 magnetic bead kit provides the fastest turnaround time with similar amplification efficiency, when compared to spin-column or other magnetic bead kits. The test cost per sample is $5.41 dollars to process 83 samples in a 96 well-plate format in less than 2 hours. Another significant finding was showing the feasibility of using as low as 12µL of liquid cytology samples for DNA methylation testing, proving that bodily fluids are a liquid biopsy alternative to plasma. Overall, this comprehensive comparison is useful in determining optimal options for efficient and cost-effective cancer DNA methylation diagnostic tests, particularly in low-resource settings. Citation Format: Fernando Zamuner, Ashley Ramos-Lopez, Amanda Garcia-Negron, Ana Purcell-Wiltz, Andrea Cortes-Ortiz, Aniris Roman, Keerthana Gosala, Eli Winkler, David Sidransky, Mariana Brait, Rafael E. Guerrero-Preston. Evaluation of silica spin-column and bead formats for rapid promoter DNA methylation analysis by qMSP in clinical and point-of-care settings [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7288.

Combined DNA Methylation and Gastric Microbiome Marker Predicts Helicobacter pylori-Negative Gastric Cancer.

While DNA methylation and gastric microbiome are each associated with gastric cancer (GC), their combined role in predicting GC remains unclear. This study investigated the potential of a combined DNA methylation and gastric microbiome signature to predict Helicobacter pylori-negative GC. In this case-control study, we conducted quantitative methylation-specific polymerase chain reaction to measure the methylation levels of DKK3, SFRP1, EMX1, NKX6-1, MIR124-3, and TWIST1 in the gastric mucosa from 75 H. pylori-negative patients, including chronic gastritis (CG), intestinal metaplasia (IM), and GC. A combined analysis of DNA methylation and gastric microbiome, using 16S rRNA gene sequencing, was performed in 30 of 75 patients. The methylation levels of DKK3, SFRP1, EMX1, MIR124-3, and TWIST1 were significantly higher in patients with GC than in controls (all q<0.05). MIR124-3 and TWIST1 methylation levels were higher in patients with IM than those with CG and also in those with GC than in those with IM (all q<0.05). A higher methylation level of TWIST1 was an independent predictor for H. pylori-negative GC after adjusting for age, sex, and atrophy (odds ratio [OR], 15.15; 95% confidence interval [CI], 1.58 to 145.46; p=0.018). The combination of TWIST1 methylation and GC microbiome index (a microbiome marker) was significantly associated with H. pylori-negative GC after adjusting for age, sex, and atrophy (OR, 50.00; 95% CI, 1.69 to 1,476; p=0.024). The combination of TWIST1 methylation and GC microbiome index may offer potential as a biomarker for predicting H. pylori-negative GC.

Abstract P521: Sleep Timing and Duration in Relation to DNA Methylation in Adolescents: An Epigenome-Wide Analysis

Background: Accumulating evidence suggests that both sleep duration and sleep timing can impact metabolic health of adolescents, potentially through epigenetic modification. The objective of this study was to investigate the relationship between sleep duration and timing and DNA methylation, one type of epigenetic modification that may be responsive to changes in sleep. Methods: Cross-sectional epigenome-wide analysis of DNA methylation was conducted to identify sleep-related CpG sites in 269 females and 233 males (14.4±2.1 years on average) participating in the Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) cohort study. Sleep duration and midpoint on weekdays and weekends were assessed using7-day wrist actigraphy (Actigraph GTX-BT), and DNA methylation in blood leukocytes was measured using the Illumina Infinium Methylation EPIC BeadChip. Linear regression was conducted to assess the relationship between sleep variables and DNA methylation at each locus on the array (using beta values), adjusting for sex, age, maternal education, batch effects, monocytes, natural killer cells, B lymphocyte, granulocyte, and naïve CD8 T cells. A false discovery rate (FDR) using the Benjamini-Hochberg method was applied to correct for multiple testing. Sex-stratified associations were also examined. Results: The average sleep duration was 8.5±1.3 hours on weekdays and 9.1±1.3 hours on weekends, and the average sleep midpoint was 3:48AM±1.4 hours on weekdays and 4.48AM±1.3 hours on weekends. At false discovery rate &lt;0.05, there were no significant associations at any of the 762,657 CpG sites. However, at a false discovery rate of &lt;0.2, there were positive associations between weekday sleep duration and 4 CpG sites (i.e., longer sleep duration associated with higher % DNA methylation), including a site in or near CpG islands annotated to the gene DENND2C. Sex-stratified analyses revealed associations were more evident in males. Conclusion: Epigenome-wide analysis identified possible associations between sleep duration and multiple CpG sites, and in a sex-specific manner. Findings suggest that sleep duration may impact the epigenome in a distinct manner from sleep timing.

Abstract P382: Epigenetic Regulation of the NF-kB Pathway by the Neural-Hematopoietic-Inflammatory Axis as a Potential Link Between Psychosocial Stress and Cardiovascular Risk: Data From the Washington DC Cardiovascular Health and Needs Assessment

Introduction: Chronic psychosocial stress (cPSS) is associated with cardiovascular disease (CVD) risk, caused in part by dysregulation of the neural-hematopoietic-inflammatory axis and epigenetic changes. cPSS may also affect NF-kB dependent pathways, suggesting a potential link to accelerated CVD risk and health inequities for populations most impacted by adverse social determinants. Hypothesis: We propose cPSS associates with greater amygdala activity (AmygA), a stress marker, and splenic activity (SpleenA), a hematopoietic activation measure. This relates to higher pro-inflammatory cytokine levels, partially due to less DNA methylation of NF-kB pathway-related genes. Methods: 60 African American adults (93.3% female, mean age 61) with CVD risk, living in the Washington, D.C. area underwent 18 FDG PET/CT to evaluate AmygA and SpleenA. DNA methylation analysis assessed epigenetic associations of the NF- κ B1/2 gene in PBMCs and ELISA- measured serum IL-1β and TNFα. Multivariable regression analysis adjusted for atherosclerotic CVD 10-year risk score and BMI was used to examine associations. Results: Greater AmygA and SpleenA were significantly associated with one another (β=0.26; p=0.003) and both were associated with greater pro-inflammatory cytokines IL1-β (AmygA:β =0.36, SpleenA:β=0.72, p&lt;0.05) and TNF-α (AmygA:β=0.31, SpleenA:β=0.58, p&lt;0.05). Further, we identified 2 significant methylation sites out of 81 on the NF- κ B1/2 gene. Notably, AmygA and SpleenA were inversely associated with the NF-κB1 cg01983105 and cg07955720 methylation sites (Table). Conclusions: We highlight a possible link between AmygA and SpleenA with decreased DNA methylation of the NF- κB gene. Our findings demonstrate a potential relationship between chronic stress-related neural activity and CVD risk through immune function and epigenetic alterations. These results should be examined in larger, diverse population-based cohorts with longitudinal data to identify intervention targets for reducing health inequities.

Alterations of DNA methylation profile in peripheral blood of children with simple obesity

PurposeTo investigate the association between DNA methylation and childhood simple obesity.MethodsGenome-wide analysis of DNA methylation was conducted on peripheral blood samples from 41 children with simple obesity and 31 normal controls to identify differentially methylated sites (DMS). Subsequently, gene functional analysis of differentially methylated genes (DMGs) was carried out. After screening the characteristic DMGs based on specific conditions, the methylated levels of these DMS were evaluated and verified by pyrosequencing. Receiver operating characteristic (ROC) curve analysis assessed the predictive efficacy of corresponding DMGs. Finally, Pearson correlation analysis revealed the correlation between specific DMS and clinical data.ResultsThe overall DNA methylation level in the obesity group was significantly lower than in normal. A total of 241 DMS were identified. Functional pathway analysis revealed that DMGs were primarily involved in lipid metabolism, carbohydrate metabolism, amino acid metabolism, human diseases, among other pathways. The characteristic DMS within the genes Transcription factor A mitochondrial (TFAM) and Piezo type mechanosensitive ion channel component 1(PIEZO1) were recognized as CpG-cg05831083 and CpG-cg14926485, respectively. Furthermore, the methylation level of CpG-cg05831083 significantly correlated with body mass index (BMI) and vitamin D.ConclusionsAbnormal DNA methylation is closely related to childhood simple obesity. The altered methylation of CpG-cg05831083 and CpG-cg14926485 could potentially serve as biomarkers for childhood simple obesity.

Physio-biochemical and DNA methylation analysis of the defense response network of wheat to drought stress

In the present work, physio-biochemical and DNA methylation analysis were conducted in wheat (Triticum aestivum L.) cultivars “Bolani” (drought-tolerant) and “Sistan” (drought-sensitive) during drought treatments: well-watered (at 90% field capacity (FC)), mild stress (at 50% FC, and severe stress (at 25% FC). During severe stress, O2•− and H2O2 content in cultivar Sistan showed significant increase (by 1.3 and 2.5-fold, respectively) relative to cultivar Bolani. In Bolani, the increased levels of radical scavenging activity (by 32%), glycine betaine (GB) (by 11.44%), proline (4-fold), abscisic acid (by 63.76%), and more stability of relative water content (RWC) (2-fold) were observed against drought-induced oxidative stress. Methylation level significantly decreased from 70.26% to 60.64% in Bolani and from 69.06% to 59.85% in Sistan during stress, and higher decreased tendency was related to CG and CHG in Bolani but CG in Sistan under severe stress. Methylation patterns showed that the highest polymorphism in Bolani was mainly as CG. As the intensity of stress increased, the enhanced physio-biochemical responses of Bolani cultivar were accompanied by a more decrease in the number of unchanged bands. According to heat map analysis, the highest difference (84.38%) in methylation patterns was observed between control and severe stress. Multivariate analysis using principal component analysis (PCA) showed a cultivar-specific methylation during stress and that methylation changes between cultivars are much higher than that of within a cultivar. Higher methylation to demethylation in Bolani (30.06 vs. 22.12%) compared to that of cultivar Sistan (23.21 vs. 30.15%) indicated more demethylation did not induce tolerance responses in Sistan. Sequencing differentially methylated fragments along with qRT-PCR analysis showed the efficient role of various DNA fragments, including demethylated fragments such as phosphoenol pyruvate carboxylase (PEPC), beta-glucosidase (BGlu), glycosyltransferase (GT), glutathione S-transferase (GST) and lysine demethylase (LSD) genes and methylated fragments like ubiquitin E2 enzyme genes in the development of drought tolerance. These results suggested the specific roles of DNA methylation in development of drought tolerance in wheat landrace.

Comparative and functional analysis unveils the contribution of photoperiod to DNA methylation, sRNA accumulation, and gene expression variations in short-day and long-day grasses.

Photoperiod employs complicated networks to regulate various developmental processes in plants, including flowering transition. However, the specific mechanisms by which photoperiod affects epigenetic modifications and gene expression variations in plants remain elusive. In this study, we conducted a comprehensive analysis of DNA methylation, small RNA (sRNA) accumulation, and gene expressions under different daylengths in facultative long-day (LD) grass Brachypodium distachyon and short-day (SD) grass rice. Our results showed that while overall DNA methylation levels were minimally affected by different photoperiods, CHH methylation levels were repressed under their favorable light conditions, particularly in rice. We identified numerous differentially methylated regions (DMRs) that were influenced by photoperiod in both plant species. Apart from differential sRNA clusters, we observed alterations in the expression of key components of the RNA-directed DNA methylation pathway, DNA methyltransferases, and demethylases, which may contribute to the identified photoperiod-influenced CHH DMRs. Furthermore, we identified many differentially expressed genes in response to different daylengths, some of which were associated with the DMRs. Notably, we discovered a photoperiod-responsive gene MYB11 in the transcriptome of B.distachyon, and further demonstrated its role as a flowering inhibitor by repressing FT1 transcription. Together, our comparative and functional analysis sheds light on the effects of daylength on DNA methylation, sRNA accumulation, and gene expression variations in LD and SD plants, thereby facilitating better designing breeding programs aimed at developing high-yield crops that can adapt to local growing seasons.

Methylation‑sensitive restriction enzyme‑droplet digital PCR assay for the one‑step highly sensitive analysis of DNA methylation hotspots.

DNA methylation is an epigenetic modification that plays a key role in several cellular processes mediating the fine regulation of gene expression. Aberrant DNA methylation is observed in a wide range of pathologies, including cancer. Since these DNA modifications are transferred to the cell progenies and are stable over the time, the analysis of DNA methylation status has been proposed for diagnostic and prognostic purposes in cancer. Currently, DNA bisulfite conversion is the gold standard method for the high‑throughput analysis of DNA methylation alterations. However, bisulfite treatment induces DNA fragmentation affecting its quality for the downstream analyses. In this field, it is mandatory to identify novel methods to overcome the limits of conventional approaches. In the present study, the Methylation‑Sensitive Restriction Enzyme‑droplet digital PCR (MSRE‑ddPCR) assay was developed as a novel sensitive method for the analysis of DNA methylation of short genomic regions, combining the MSRE assay with the high‑sensitivity ddPCR and using an exogenous methylation sequence as control. Setup and validation experiments were performed analyzing a methylation hotspot of the Solute Carrier Family 22 Member 17 in DNA samples derived from melanoma cell lines as well as from tissues and serum samples obtained from patients with melanoma and healthy controls. Compared with the standard MSRE approaches, the MSRE‑ddPCR assay is more appropriate for the analysis of DNA methylation (methDNA) in samples with low amounts of DNA (up to 0.651 ng) showing a greater sensitivity. These findings suggested the potential clinical application of MSRE‑ddPCR paving the way to the analysis of other methDNA hotspots in different tumors.

DNA methylation clocks for estimating biological age in Chinese cohorts.

Epigenetic clocks are accurate predictors of human chronological age based on the analysis of DNA methylation (DNAm) at specific CpG sites. However, a systematic comparison between DNA methylation data and other omics datasets has not yet been performed. Moreover, available DNAm age predictors are based on datasets with limited ethnic representation. To address these knowledge gaps, we generated and analyzed DNA methylation datasets from two independent Chinese cohorts, revealing age-related DNAm changes. Additionally, a DNA methylation aging clock (iCAS-DNAmAge) and a group of DNAm-based multi-modal clocks for Chinese individuals were developed, with most of them demonstrating strong predictive capabilities for chronological age. The clocks were further employed to predict factors influencing aging rates. The DNAm aging clock, derived from multi-modal aging features (compositeAge-DNAmAge), exhibited a close association with multi-omics changes, lifestyles, and disease status, underscoring its robust potential for precise biological age assessment. Our findings offer novel insights into the regulatory mechanism of age-related DNAm changes and extend the application of the DNAm clock for measuring biological age and aging pace, providing the basis for evaluating aging intervention strategies.