Whole-Genome Mapping of Epigenetic Modification of 5-Formylcytosine at Single-Base Resolution by Chemical Labeling Enrichment and Deamination Sequencing

DNA cytosine methylation (5-methylcytosine, 5mC) is a predominant epigenetic modification that plays a critical role in a variety of biological and pathological processes in mammals. In active DNA demethylation, the 10-11 translocation (TET) dioxygenases can sequentially oxidize 5mC to generate three modified forms of cytosine, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). Beyond being a demethylation intermediate, recent studies have shown that 5fC has regulatory functions in gene expression and chromatin organization. While some methods have been developed to detect 5fC, genome-wide mapping of 5fC at base resolution is still highly desirable. Herein, we propose a chemical labeling enrichment and deamination sequencing (CLED-seq) method for detecting 5fC in genomic DNA at single-base resolution. The CLED-seq method utilizes selective labeling and enrichment of 5fC-containing DNA fragments, followed by deamination mediated by apolipoprotein B mRNA-editing catalytic polypeptide-like 3A (APOBEC3A or A3A) and sequencing. In the CLED-seq process, while all C, 5mC, and 5hmC are interpreted as T during sequencing, 5fC is still read as C, enabling the precise detection of 5fC in DNA. Using the proposed CLED-seq method, we accomplished genome-wide mapping of 5fC in mouse embryonic stem cells. The mapping study revealed that promoter regions enriched with 5fC overlapped with H3K4me1, H3K4me3, and H3K27ac marks. These findings suggest a correlation between 5fC marks and active gene expression in mESCs. In conclusion, CLED-seq is a straightforward, bisulfite-free method that offers a valuable tool for detecting 5fC in genomes at a single-base resolution.

Whole-Genome Sequencing of 5-Hydroxymethylcytosine at Base Resolution by Bisulfite-Free Single-Step Deamination with Engineered Cytosine Deaminase

The epigenetic modification 5-hydroxymethylcytosine (5hmC) plays a crucial role in the regulation of gene expression. Although some methods have been developed to detect 5hmC, direct genome-wide mapping of 5hmC at base resolution is still highly desirable. Herein, we proposed a single-step deamination sequencing (SSD-seq) method, designed to precisely map 5hmC across the genome at single-base resolution. SSD-seq takes advantage of a screened engineered human apolipoprotein B mRNA-editing catalytic polypeptide-like 3A (A3A) protein, known as eA3A-v10, to selectively deaminate cytosine (C) and 5-methylcytosine (5mC) but not 5hmC. During sequencing, the deaminated C and 5mC are converted to uracil (U) and thymine (T), read as T in the sequencing data. However, 5hmC remains unaffected by eA3A-v10 and is read as C during sequencing. Consequently, the presence of C in the sequence reads indicates the original 5hmC. We applied SSD-seq to generate a base-resolution map of 5hmC in human lung tissue. Our findings revealed that 5hmC was predominantly localized to CpG dinucleotides. Furthermore, the base-resolution map of 5hmC generated by SSD-seq demonstrated a strong correlation with prior ACE-seq results. The advantages of SSD-seq are its single-step process, absence of bisulfite treatment or DNA glycosylation, cost effectiveness, and ability to detect and quantify 5hmC directly at single-base resolution.

Preliminary Study of Whole-Genome Bisulfite Sequencing and Transcriptome Sequencing in VHL Disease-Associated ccRCC

BACKGROUND

Von Hippel-Lindau (VHL) disease is an autosomal dominant hereditary tumor syndrome with an incidence of approximately 1/36,000. VHL disease-associated clear cell renal cell carcinoma (ccRCC) is the most common congenital RCC. Although recent advances in treating RCC have improved the long-term prognosis of patients with VHL disease, kidney cancer is still the leading cause of death in these patients. Therefore, finding new targets for diagnosing and treating VHL disease-associated ccRCC is still essential.

METHODS

In this study, we collected matched tumor tissues and normal samples from 25 patients with VHL disease-associated ccRCC, diagnosed and surgically treated in the Department of Urology, Peking University First Hospital. After screening, we performed whole genome bisulfite sequencing (WGBS) on 23 pairs of tissues and RNA-seq on 6 pairs of tissues. And we also compared the VHL disease-associated ccRCC transcriptome data with the sporadic ccRCC transcriptome data from the The Cancer Genome Atlas (TCGA) public database RESULTS: We found that the methylation level of VHL disease-associated ccRCC tumor tissues was significantly lower than that of normal tissues. The tumor tissues showed a difference in the copy number of 3p loss and 5q and 7q gain compared with normal tissues. We integrated RNA-seq and WGBS data to reveal methylation candidate genes associated with VHL disease-associated ccRCC; our results showed 124 hypermethylated and downregulated genes, and 245 hypomethylated and upregulated genes. By comparing the VHL disease-associated ccRCC transcriptome data with the sporadic ccRCC transcriptome data from the TCGA public database, we found that the major pathways of differential gene enrichment differed between them.

CONCLUSIONS

Our study mapped the multiomics of copy number variation, methylation and mRNA level changes in tumor and normal tissues of clear cell renal cell carcinoma with VHL syndrome, which provides a solid foundation for the mechanistic study, biomarker screening, and therapeutic target discovery of clear cell renal cell carcinoma.

Single-Nucleotide Resolution Mapping of N6-Methyladenine in Genomic DNA

N6-Methyladenine (6mA) is a naturally occurring DNA modification in both prokaryotes and eukaryotes. Herein, we developed a deaminase-mediated sequencing (DM-seq) method for genome-wide mapping of 6mA at single-nucleotide resolution. The method capitalizes on the selective deamination of adenine, but not 6mA, in DNA mediated by an evolved adenine deaminase, ABE8e. By employing this method, we achieved genome-wide mapping of 6mA in Escherichia coli and in mammalian mitochondrial DNA (mtDNA) at single-nucleotide resolution. We found that the 6mA sites are mainly located in the GATC motif in the E. coli genome. We also identified 17 6mA sites in mtDNA of HepG2 cells, where all of the 6mA sites are distributed in the heavy strand of mtDNA. We envision that DM-seq will be a valuable tool for uncovering new functions of 6mA in DNA and for exploring its potential roles in mitochondria-related human diseases.

An experimental workflow for identifying RNA m6A alterations in cellular senescence by methylated RNA immunoprecipitation sequencing

N6-methyladenosine (m6A), the most prevalent mRNA modification in eukaryotic cells, is known to play regulatory roles in a wide array of biological processes, including aging and cellular senescence. To investigate such roles, the m6A modification can be identified across the entire transcriptome by immunoprecipitation of methylated RNA with an anti-m6A antibody, followed by high-throughput sequencing (meRIP-seq or m6A-seq). Presented here is a protocol for employing meRIP-seq to profile the RNA m6A landscape in senescent human cells. We described, in detail, sample preparation, mRNA isolation, immunoprecipitation, library preparation, sequencing, bioinformatic analysis and validation. We also provided tips and considerations for the optimization and interpretation of the results. Our protocol serves as a methodological resource for investigating transcriptomic m6A alterations in cellular senescence as well as a valuable paradigm for the validation of genes of interest.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

m6A epitranscriptomic regulation of tissue homeostasis during primate aging

How N⁶-methyladenosine (m⁶A), the most abundant mRNA modification, contributes to primate tissue homeostasis and physiological aging remains elusive. Here, we characterize the m⁶A epitranscriptome across the liver, heart and skeletal muscle in young and old nonhuman primates. Our data reveal a positive correlation between m⁶A modifications and gene expression homeostasis across tissues as well as tissue-type-specific aging-associated m⁶A dynamics. Among these tissues, skeletal muscle is the most susceptible to m⁶A loss in aging and shows a reduction in the m⁶A methyltransferase METTL3. We further show that METTL3 deficiency in human pluripotent stem cell-derived myotubes leads to senescence and apoptosis, and identify NPNT as a key element downstream of METTL3 involved in myotube homeostasis, whose expression and m⁶A levels are both decreased in senescent myotubes. Our study provides a resource for elucidating m⁶A-mediated mechanisms of tissue aging and reveals a METTL3-m⁶A-NPNT axis counteracting aging-associated skeletal muscle degeneration.

UCseek: ultrasensitive early detection and recurrence monitoring of urothelial carcinoma by shallow-depth genome-wide bisulfite sequencing of urinary sediment DNA

BACKGROUND

Current methods for the detection and surveillance of urothelial carcinomas (UCs) are often invasive, costly, and not effective for low-grade, early-stage, and minimal residual disease (MRD) tumors. We aimed to develop and validate a model from urine sediments to predict different grade and stage UCs with low cost and high accuracy.

METHODS

We collected 167 samples, including 90 tumors and 77 individuals without tumors, as a discovery cohort. We assessed copy number variations and methylation values for them and constructed a diagnostic classifier to detect UC, UCseek, by using an individual read-based method and support vector machine. The performance of UCseek was validated in an independent cohort derived from three hospitals (n = 206) and a relapse cohort (n = 42) for monitoring recurrence.

FINDINGS

We constructed UCseek, which could predict UCs with high sensitivity (92.7%), high specificity (90.7%), and high accuracy (91.7%) in the independent validation set. The accuracy of UCseek in low-grade and early-stage patients reached 91.8% and 94.3%, respectively. Notably, UCseek retained great performance at ultralow sequencing depths (0.3X-0.5X). It also demonstrated a powerful ability to monitor recurrence in a surveillance cohort compared with cystoscopy (90.91% vs. 59.09%).

INTERPRETATION

We optimized an improved approach named UCseek for the noninvasive diagnosis and monitoring of UCs in both low- and high-grade tumors and in early- and advanced-stage tumors, even at ultralow sequencing depths, which may reduce the burden of cystoscopy and blind second surgery.

FUNDING

A full list of funding bodies that contributed to this study can be found in the Acknowledgments section.

Single-cell atlases link macrophages and CD8+ T-cell subpopulations to disease progression and immunotherapy response in urothelial carcinoma

Rationale: Immune checkpoint inhibitors (ICIs) have revolutionized the management of locally advanced or metastatic urothelial carcinoma. Strikingly, compared to urothelial carcinoma of the bladder (UCB), upper tract urothelial carcinoma (UTUC) has a higher response rate to ICIs. The stratification of patients most likely to benefit from ICI therapy remains a major clinical challenge. Methods: In this study, we performed the first single-cell RNA sequencing (scRNA-seq) study of 13 surgical tissue specimens from 12 patients with UTUC. The key results were validated by the analysis of two independent cohorts with bulk RNA-seq data for UCB (n = 404) and UTUC (n = 158) and one cohort of patients with metastatic urothelial carcinoma (mUC) who were treated with atezolizumab (n = 348). Results: Using scRNA-seq, we observed a higher proportion of tumor-infiltrating immune cells in locally advanced UTUC. Similar prognostically relevant intrinsic basal and luminal-like epithelial subtypes were found in both UTUC and UCB, although UTUC is predominantly of the luminal subtype. We also discovered that immunosuppressive macrophages and exhausted T-cell subpopulations were enriched in the basal subtype and showed enhanced interactions. Furthermore, we developed a gene expression signature (Macro-C3 score) capturing the immunosuppressive macrophages that better predicts outcomes than the currently established subtypes. We also developed a computational method to model immune evasion, and the Macro-C3 score predicted therapeutic response of mUC treated with first-line anti-PD-L1 inhibitors in patients with lower basal scores. Conclusions: Overall, the distinct microenvironment and Macro-C3 score provide an explanation for ICI efficacy in urothelial carcinoma and reveal new candidate regulators of immune evasion, suggesting potential therapeutic targets for improving antitumor immunity in the basal subtype.

Regional gain and global loss of 5-hydroxymethylcytosine coexist in genitourinary cancers and regulate different oncogenic pathways

BACKGROUND

DNA 5-hydroxymethylcytosine (5hmC) is produced by dynamic 5mC oxidation process contributing to tissue specification, and loss of 5hmC has been reported in multiple cancers including genitourinary cancers. However, 5hmC is also cell-type specific, and its variability may exist between differentiated tumor cells and cancer stem cells. Thus, cancer-associated changes in 5hmC may be contributed by distinct sets of tumor cells within the tumor tissues.

RESULTS

Here, we applied a sensitive immunoprecipitation-based method (hMeDIP-seq) to analyze 5hmC changes during genitourinary carcinogenesis (including prostate, urothelial and kidney). We confirmed the tissue-specific distribution of 5hmC in genitourinary tissues and identified regional gain and global loss of 5hmC coexisting in genitourinary cancers. The genes with gain of 5hmC during tumorigenesis were functionally enriched in regulating stemness and hypoxia, whereas were associated with poor clinical prognosis irrespective of their differences in tumor type. We identified that gain of 5hmC occurred in soft fibrin gel-induced 3D tumor spheres with a tumor-repopulating phenotype in two prostate cancer cell lines, 22RV1 and PC3, compared with conventional two-dimensional (2D) rigid dishes. Then, we defined a malignant signature derived from the differentially hydroxymethylated regions affected genes of cancer stem-like cells, which could predict a worse clinical outcome and identified phenotypically malignant populations of cells from prostate cancer tumors. Notably, an oxidation-resistant vitamin C derivative, ascorbyl phosphate magnesium, restored 5hmC and killed the cancer stem cell-like cells leading to apoptosis in prostate cancer cell lines.

CONCLUSIONS

Collectively, our study dissects the regional gain of 5hmC in maintaining cancer stem-like cells and related to poor prognosis, which provides proof of concept for an epigenetic differentiation therapy with vitamin C by 5hmC reprogramming.

DNA methylation subtypes guiding prognostic assessment and linking to responses the DNA methyltransferase inhibitor SGI-110 in urothelial carcinoma

BACKGROUND

At present, the extent and clinical relevance of epigenetic differences between upper tract urothelial carcinoma (UTUC) and urothelial carcinoma of the bladder (UCB) remain largely unknown. Here, we conducted a study to describe the global DNA methylation landscape of UTUC and UCB and to address the prognostic value of DNA methylation subtype and responses to the DNA methyltransferase inhibitor SGI-110 in urothelial carcinoma (UC).

METHODS

Using whole-genome bisulfite sequencing (n = 49 samples), we analyzed epigenomic features and profiles of UTUC (n = 36) and UCB (n = 9). Next, we characterized potential links between DNA methylation, gene expression (n = 9 samples), and clinical outcomes. Then, we integrated an independent UTUC cohort (Fujii et al., n = 86) and UCB cohort (TCGA, n = 411) to validate the prognostic significance. Furthermore, we performed an integrative analysis of genome-wide DNA methylation and gene expression in two UC cell lines following transient DNA methyltransferase inhibitor SGI-110 treatment to identify potential epigenetic driver events that contribute to drug efficacy.

RESULTS

We showed that UTUC and UCB have very similar DNA methylation profiles. Unsupervised DNA methylation classification identified two epi-clusters, Methy-High and Methy-Low, associated with distinct muscle-invasive statuses and patient outcomes. Methy-High samples were hypermethylated, immune-infiltrated, and enriched for exhausted T cells, with poor clinical outcome. SGI-110 inhibited the migration and invasion of Methy-High UC cell lines (UMUC-3 and T24) by upregulating multiple antitumor immune pathways.

CONCLUSIONS

DNA methylation subtypes pave the way for predicting patient prognosis in UC. Our results provide mechanistic rationale for evaluating SGI-110 in treating UC patients in the clinic.

POS0724 RISK FACTORS FOR CORONARY ARTERY DISEASE IN CHINESE PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS: A MULTI-CENTER, RETROSPECTIVE, COHORT STUDY

Background

Coronary artery disease (CAD) not only has an increased prevalence but also is a major cause of premature mortality in systemic lupus erythematosus (SLE) [1, 2]. However, information is limited regarding the risk factors for CAD in Chinese patients with SLE.

Objectives

To assess the risk factors for CAD in Chinese patients with SLE.

Methods

This multi-center, retrospective, cohort study included 3778 consecutive SLE patients, with CAD (CAD group) or without a medical history of CAD (control group). CAD was defined as a coronary stenosis ≥50% in any major epicardial coronary vessel detected by coronary angiography or a history of myocardial infarction confirmed by medical records. General parameters, clinical features, laboratory tests and medical therapies were compared between groups, and the risk factors for CAD in SLE were analyzed by logistic regression analysis.

Results

The age at baseline was older, male ratio was higher and body mass index was greater in CAD group (all P<0.001). Traditional CAD risk factors including diabetes mellitus, hypertension, dyslipidemia, family history of CAD and smoking were more common in CAD group (all P<0.001) (Figure 1). SLE Disease Activity Index 2000 was greater (P=0.012), hyperuricemia and elevated C-reactive protein (CRP) were more prevalent (both P<0.001), and an increased corticosteroids’ usage (P=0.018) was detected in CAD group (Table 1). Binary logistic regression analysis showed hyperuricemia (odds ratio: 3.082, 95% confidence interval: 1.283-7.403; P=0.012) and CRP (odds ratio: 7.248, 95% confidence interval: 2.931-17.925; P<0.001) were independent risk factors for CAD in SLE patients.

Table 1.

Comparison of clinical features in SLE patients between CAD group and control group.

ParametersControl group (n=3732)CAD group (n=46)PAge at baseline [years, median (P25, P75)]35.00 (29.00, 45.00)59.50 (50.25, 67.75)<0.001Male, n (%)296 (7.94)11 (23.91)<0.001Disease duration [years, median (P25, P75)]8.00 (4.00, 12.00)10.00 (4.00, 19.00)0.173Body mass index [kg/m2, median (P25, P75)]21.77 (19.63, 24.16)23.50 (22.09, 25.36)<0.001Renal disorder, n (%)1737 (46.57)9 (19.57)<0.001Neurologic disorder, n (%)595 (15.95)3 (6.52)0.082Thrombocytopenia, n (%)859 (23.03)8 (17.39)0.366SLEDAI-2K [median (P25, P75)]3.00 (0.00, 8.00)5.50 (1.50, 14.00)0.012Elevated creatinine, n (%)295 (7.91)10 (21.74)0.002Hyperuricemia, n (%)209 (5.60)16 (34.78)<0.001Elevated ESR, n (%)951 (25.5)22 (47.83)0.001Elevated CRP, n (%)210 (5.63)15 (32.61)<0.001Positive aPL, n (%)734 (19.68)11 (23.91)0.474Corticosteroids, n (%)2752 (73.78)41 (89.13)0.018Immunosuppressants, n (%)2950(79.09)37 (80.43)0.823

Abbreviations: aPL, antiphospholipid antibody; CAD, coronary artery disease; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; SLE, systemic lupus erythematosus; SLEDAI-2K, SLE Disease Activity Index 2000. P <0.05 are shown as italics and bold.

Figure 1.

Comparison of traditional risk factors in SLE patients between CAD group and control group. Abbreviations: CAD, coronary artery disease; SLE, systemic lupus erythematosus. All P<0.001.

Conclusion

Hyperuricemia and CRP are independent risk factors for CAD in SLE patients. This study highlights the association between hyperuricemia, CRP and CAD burden in SLE, and might provide a modifiable perspective on improving SLE outcomes.

References

[1]Gonzalez LA, Alarcon GS. The evolving concept of SLE comorbidities [J]. Expert Rev Clin Immunol, 2017, 13(8): 753-768.

[2]Kostopoulou M, Nikolopoulos D, Parodis I, et al. Cardiovascular Disease in Systemic Lupus Erythematosus: Recent Data on Epidemiology, Risk Factors and Prevention [J]. Curr Vasc Pharmacol, 2020, 18(6): 549-565.

Disclosure of Interests

None declared

Single-Cell RNA-seq Reveals a Developmental Hierarchy Super-Imposed Over Subclonal Evolution in the Cellular Ecosystem of Prostate Cancer

Prostate cancer (PCa) is a complex disease. An ongoing accumulation of mutations results in increased genetic diversity, with the tumor acquiring distinct subclones. However, non-genetic intra-tumoral heterogeneity, the cellular differentiation state and the interplay between subclonal evolution and transcriptional heterogeneity are poorly understood. Here, the authors perform single-cell RNA sequencing from 14 untreated PCa patients. They create an extensive cell atlas of the PCa patients and mapped developmental states onto tumor subclonal evolution. They identify distinct subclones across PCa patients and then stratify tumor cells into four transcriptional subtypes, EMT-like (subtype 0), luminal A-like (subtype 1), luminal B/C-like (subtype 2), and basal-like (subtype 3). These subtypes are hierarchically organized into stem cell-like and differentiated status. Strikingly, multiple subclones within a single primary tumor present with distinct combinations of preferential subtypes. In addition, subclones show different communication strengths with other cell types within the tumor ecosystem, which may modulate the distinct transcriptional subtypes of the subclones. Notably, by integrating TCGA data, they discover that both tumor cell transcriptional heterogeneity and cellular ecosystem diversity correlate with features of a poor prognosis. Collectively, their study provides the analysis of subclonal and transcriptional heterogeneity and its implication for patient prognosis.

Pyroptosis-Related Signature Predicts Prognosis and Immunotherapy Efficacy in Muscle-Invasive Bladder Cancer

Pyroptosis has profound impacts on tumor cell proliferation, invasion, and metastasis and is of great clinical significance for different cancers. However, the role of pyroptosis in the progression and prognosis of muscle invasive bladder cancer (MIBC) remains poorly characterized. Here, we collected multicenter MIBC data and performed integrated analysis to dissect the role of pyroptosis in MIBC and provide an optimized treatment for this disease. Based on transcriptomic data, we developed a novel prognostic model named the pyroptosis-related gene score (PRGScore), which summarizes immunological features, genomic alterations, and clinical characteristics associated with the pyroptosis phenotype. Samples with high PRGScore showed enhancement in CD8⁺ T cell effector function, antigen processing machinery and immune checkpoint and better response to immunotherapy by programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors, which indicates that PRGScore is a valuable signature in the identification of populations sensitive to immune checkpoint inhibitors. Collectively, our study provides insights into further research targeting pyroptosis and its tumor immune microenvironment (TME) and offers an opportunity to optimize the treatment of MIBC.

Decoding the multicellular ecosystem of vena caval tumor thrombus in clear cell renal cell carcinoma by single-cell RNA sequencing

Background

Vascular invasion with tumor thrombus frequently occurs in advanced renal cell carcinoma (RCC). Thrombectomy is one of the most challenging surgeries with high rate of perioperative morbidity and mortality. However, the mechanisms driving tumor thrombus formation are poorly understood which is required for designing effective therapy for eliminating tumor thrombus.

Results

We perform single-cell RNA sequencing analysis of 19 surgical tissue specimens from 8 clear cell renal cell carcinoma (ccRCC) patients with tumor thrombus. We observe tumor thrombus has increased tissue resident CD8⁺ T cells with a progenitor exhausted phenotype compared with the matched primary tumors. Remarkably, macrophages, malignant cells, endothelial cells and myofibroblasts from TTs exhibit enhanced remodeling of the extracellular matrix. The macrophages and malignant cells from primary tumors represent proinflammatory states, but also increase the expression of immunosuppressive markers compared to tumor thrombus. Finally, differential gene expression and interaction analyses reveal that tumor-stroma interplay reshapes the extracellular matrix in tumor thrombus associated with poor survival.

Conclusions

Our comprehensive picture of the ecosystem of ccRCC with tumor thrombus provides deeper insights into the mechanisms of tumor thrombus formation, which may aid in the design of effective neoadjuvant therapy to promote downstaging of tumor thrombus and decrease the perioperative morbidity and mortality of thrombectomy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13059-022-02651-9.

Metabolism-Related Signature Analysis Uncovers the Prognostic and Immunotherapeutic Characteristics of Renal Cell Carcinoma

Renal cell carcinoma (RCC) is one of the most common urological cancers. RCC has a poor prognosis and is considered a metabolic disease. It has been reported that many metabolic pathways are associated with the development of RCC. However, the prognostic value of metabolism-related genes in RCC is unclear. We herein aimed to establish a scoring system based on the gene expression profile of metabolic genes to evaluate the response to immunotherapy and predict the prognosis of RCC. In this study, we collected multicentre RCC data and performed integrated analysis to characterize the role of tumour metabolism in RCC and explore the relationship between metabolism and prognosis and immune therapy. Based on transcriptomic data, metabolism-related genes were used for nonnegative matrix factorization clustering. We obtained three subclasses of RCC (M1, M2, and M3), and they are associated with different prognoses and immune infiltrate levels. Then, based on the pathway activity of 113 metabolism-related gene signatures, we classified patients into three distinct metabolism-related signatures. Finally, we provide a metabolism-related pathway score (MRPScore) that is significantly associated with RCC prognosis and the response to immunotherapy. Taken together, in this study, we established an RCC classification system based on metabolic gene expression profiles that could further the understanding of the diversity of RCC. We also present the MRPScore, which may be used as an indicator to predict the response to clinical immune therapy.

Vitamin C Deficiency Causes Cell Type-Specific Epigenetic Reprogramming and Acute Tubular Necrosis in a Mouse Model

BACKGROUND

Vitamin C deficiency is found in patients with variable kidney diseases. However, the role of vitamin C as an epigenetic regulator in renal homeostasis and pathogenesis remains largely unknown.

METHODS

We showed that vitamin C deficiency leads to acute tubular necrosis (ATN) using a vitamin C-deficient mouse model (Gulo knock-out). DNA/RNA epigenetic modifications and injured S3 proximal tubule cells were identified in the vitamin C-deficient kidneys using whole-genome bisulfite sequencing, methylated RNA immunoprecipitation sequencing, and single-cell RNA sequencing.

RESULTS

Integrated evidence suggested that epigenetic modifications affected the proximal tubule cells and fenestrated endothelial cells, leading to tubule injury and hypoxia through transcriptional regulation. Strikingly, loss of DNA hydroxymethylation and DNA hypermethylation in vitamin C-deficient kidneys preceded the histologic sign of tubule necrosis, indicating the causality of vitamin C-induced epigenetic modification in ATN. Consistently, prophylactic supplementation of an oxidation-resistant vitamin C derivative, ascorbyl phosphate magnesium, promoted DNA demethylation and prevented the progression of cisplatin-induced ATN.

CONCLUSIONS

Vitamin C played a critical role in renal homeostasis and pathogenesis in a mouse model, suggesting vitamin supplementation may be an approach to lower the risk of kidney injury.

Construction of diagnostic and subtyping models for renal cell carcinoma by genome-wide DNA methylation profiles

Background

Renal cell carcinoma (RCC) is one of the most common urological cancers and has a poor prognosis. RCC is classified into several subtypes, among which kidney renal clear cell carcinoma (KIRC) and kidney renal papillary cell carcinoma (KIRP) are the two most common subtypes. Due to the lack of adequate screening and comparative analysis of RCC subtypes, effective diagnosis and treatment strategies have not yet been achieved.

Methods

In this study, 450K methylation array data were collected from The Cancer Genome Atlas (TCGA). The ‘limma moderated t-test’ and LASSO were used to construct diagnostic and subtyping models, and survival analysis was conducted online by GEPIA.

Results

We built a model with 15 methylation sites, which showed high diagnostic and subtyping performance in specificity and sensitivity. At the same time, for potential clinical usability, we calculated the diagnostic and subtyping scores to classify RCC from normal tissue and distinguish the different RCC subtypes. Additionally, the CpG sites were mapped to their corresponding genes, which could also be used to predict the prognosis of RCC.

Conclusions

Different methylation sites can be used as diagnostic and subtyping markers that are specific to RCC and RCC subtypes (KIRC and KIRP) with high sensitivity and accuracy.

Ascorbic acid induced TET2 enzyme activation enhances cancer immunotherapy efficacy in renal cell carcinoma

Exploring the regulatory mechanism of PD-L1 in renal cancer is one of the key strategies to improve the response of renal cancer patients to checkpoint blockade therapy. In this study, the synergistic effect of ascorbic acid (vitamin C) supplementation and the impact of TET2 depletion on anti-PD-L1 therapy were determined in xenograft model experiments. Lymphocyte infiltration and chemokine expression were determined using flow cytometry and qRT-PCR. To determine the downstream targets of TET2, we performed hMeDip-seq and RNA-seq analyses. The molecular mechanism was further confirmed by hMeDip-qPCR, MeDip-qPCR, bisulfite sequencing, Western blotting, qRT-PCR and xenograft model experiments in vitro and in vivo. The present study demonstrated that ascorbic acid enhanced the efficacy of immunotherapy and that the loss of TET2 function enabled renal cancer cells to evade antitumor immunity. Ascorbic acid treatment significantly increased the intratumoral infiltration of T cells and the expression of cytokines and chemokines, while the loss of TET2 impaired the infiltration of T cells and the expression of cytokines and chemokines. TET2 was recruited to IRF1 by IFN-γ-STAT1 signaling, thereby maintaining IRF1 demethylation and ultimately inducing PD-L1 expression. These results suggest a new strategy of stimulating TET activity to improve immunotherapy for renal cell carcinoma.

Genome-wide mapping of N4-methylcytosine at single-base resolution by APOBEC3A-mediated deamination sequencing

N⁴-methylcytosine (4mC) is a natural DNA modification occurring in thermophiles and plays important roles in restriction-modification (R-M) systems in bacterial genomes. However, the precise location and sequence context of 4mC in the whole genome are limited. In this study, we developed an APOBEC3A-mediated deamination sequencing (4mC-AMD-seq) method for genome-wide mapping of 4mC at single-base resolution. In the 4mC-AMD-seq method, cytosine and 5-methylcytosine (5mC) are deaminated by APOBEC3A (A3A) protein to generate uracil and thymine, both of which are read as thymine in sequencing, while 4mC is resistant to deamination and therefore read as cytosine. Thus, the readouts of cytosines from sequencing could manifest the original 4mC sites in genomes. With the 4mC-AMD-seq method, we achieved the genome-wide mapping of 4mC in Deinococcus radiodurans (D. radiodurans). In addition, we confirmed that 4mC, but not 5mC, was the major modification in the D. radiodurans genome. We identified 1586 4mC sites in the genome of D. radiodurans, among which 564 sites were located in the CCGCGG motif. The average methylation levels in the CCGCGG motif and non-CCGCGG sequence were 70.0% and 22.8%, respectively. We envision that the 4mC-AMD-seq method will facilitate the investigation of 4mC functions, including the 4mC-involved R-M systems, in uncharacterized but potentially useful strains.

Genome-wide mapping of N⁴-methylcytosine (4mC) at single-base resolution with APOBEC3A-mediated deamination sequencing (4mC-AMD-seq).

The RNA N6-Methyladenosine Methyltransferase METTL3 Promotes the Progression of Kidney Cancer via N6-Methyladenosine-Dependent Translational Enhancement of ABCD1

The role of N6-methyladenosine (m⁶A)-modifying proteins in cancer progression depends on the cell type and mRNA affected. However, the biological role and underlying mechanism of m⁶A in kidney cancer is limited. Here, we discovered the variability in m⁶A methyltransferase METTL3 expression was significantly increased in clear cell renal cell carcinoma (ccRCC) the most common subtype of renal cell carcinoma (RCC), and high METTL3 expression predicts poor prognosis in ccRCC patients using a dataset from The Cancer Genome Atlas (TCGA). Importantly, knockdown of METTL3 in ccRCC cell line impaired both cell migration capacity and tumor spheroid formation in soft fibrin gel, a mechanical method for selecting stem-cell-like tumorigenic cells. Consistently, overexpression of METTL3 but not methyltransferase activity mutant METTL3 can promote cell migration, spheroid formation in cell line and tumor growth in xenograft model. Transcriptional profiling of m⁶A in ccRCC tissues identified the aberrant m⁶A transcripts were enriched in cancer-related pathways. Further m⁶A-sequencing of METTL3 knockdown cells and functional studies confirmed that translation of ABCD1, an ATP-binding cassette (ABC) transporter of fatty acids, was inhibited by METTL3 in m⁶A-dependent manner. Moreover, knockdown of ABCD1 in ccRCC cells decreased cancer cell migration and spheroid formation, and upregulation of ABCD1 acts as an adverse prognosis factor of kidney cancer patients. In summary, our study identifies that METTL3 promotes ccRCC progression through m⁶A modification-mediated translation of ABCD1, providing an epitranscriptional insight into the molecular mechanism in kidney cancer.

Copy Number Signatures and Clinical Outcomes in Upper Tract Urothelial Carcinoma

Tumor staging of upper tract urothelial carcinomas (UTUCs) is relatively difficult to assert accurately before surgery. Here, we used copy number (CN) signatures as a tool to explore their clinical significance of molecular stratification in UTUC. CN signatures were extracted by non-negative matrix factorization from the whole-genome sequencing (WGS) data of 90 Chinese UTUC primary tumor samples. A validation UTUC cohort (n = 56) and a cohort from urinary cell-free DNA (cfDNA) of urothelial cancer patients (n = 94) and matched primary tumors were also examined. Survival analyses were measured using the Kaplan–Meier, and Cox regression was used for multivariate analysis. Here, we identified six CN signatures (Sig1–6). Patients with a high contribution of Sig6 (Sig6high) were associated with higher microsatellite instability level and papillary architecture and had a favorable outcome. Patients with a low weighted genome integrity index were associated with positive lymph node and showed the worst outcome. Sig6high was identified to be an independently prognostic factor. The predictive significance of CN signature was identified by a validation UTUC cohort. CN signatures retained great concordance between primary tumor and urinary cfDNA. In conclusion, our results reveal that CN signature assessment for risk stratification is feasible and provides a basis for clinical studies that evaluate therapeutic interventions and prognosis.

Genome-wide R-loop Landscapes during Cell Differentiation and Reprogramming

DNA:RNA hybrids play key roles in both physiological and disease states by regulating chromatin and genome organization. Their homeostasis during cell differentiation and cell plasticity remains elusive. Using an isogenic human stem cell platform, we systematically characterize R-loops, DNA methylation, histone modifications, and chromatin accessibility in pluripotent cells and their lineage-differentiated derivatives. We confirm that a portion of R-loops formed co-transcriptionally at pluripotency genes in pluripotent stem cells and at lineage-controlling genes in differentiated lineages. Notably, a subset of R-loops maintained after differentiation are associated with repressive chromatin marks on silent pluripotency genes and undesired lineage genes. Moreover, in reprogrammed pluripotent cells, cell-of-origin-specific R-loops are initially present but are resolved with serial passaging. Our analysis suggests a multifaceted role of R-loops in cell fate determination that may serve as an additional layer of modulation on cell fate memory and cell plasticity.

Enhanced Detection of Genitourinary Cancers Using Fragmentation and Copy Number Profiles Obtained from Urinary Cell-Free DNA

BACKGROUND

Recent studies have reported that examining the fragmentation profiles (FP) of plasma cell-free DNA (cfDNA) further improves the clinical sensitivity of tumor detection. We hypothesized that considering the differences of the FP of urinary cfDNA would increase the clinical sensitivity of genitourinary (GU) cancer detection.

METHODS

177 patients with GU cancer and 94 individuals without tumors were enrolled in the discovery cohort. An independent validation dataset comprising 30 patients without tumors and 66 patients with GU cancer was also collected. We constructed an ensemble classifier, GUIDER, to detect and localize GU cancers using fragmentation and copy number profiles obtained from shallow whole-genome sequencing of urinary cfDNA.

RESULTS

Urinary cfDNA of patients with GU cancer had a higher proportion of long fragments (209-280 bp) and a lower proportion of short fragments (140-208 bp) compared to controls. The overall mean classification accuracy of the FP was 74.62%-85.39% for different algorithms, and integration of the FP and copy number alteration (CNA) features further enhanced the classification of samples from patients with GU cancer. The mean diagnostic accuracy was further improved by the ensemble classifier GUIDER, which integrated the FP and CNA profiles and resulted in a higher mean accuracy (87.52%) compared to the analysis performed without FP features (74.62%). GUIDER performed well in an independent validation dataset.

CONCLUSIONS

The lengthening and shortening of urinary cfDNA within specific size ranges were identified in patients with GU cancer. Integration of the FP should further enhance the ability to use urinary cfDNA as a molecular diagnostic tool.

METTL3 counteracts premature aging via m6A-dependent stabilization of MIS12 mRNA

N6-Methyladenosine (m6A) messenger RNA methylation is a well-known epitranscriptional regulatory mechanism affecting central biological processes, but its function in human cellular senescence remains uninvestigated. Here, we found that levels of both m6A RNA methylation and the methyltransferase METTL3 were reduced in prematurely senescent human mesenchymal stem cell (hMSC) models of progeroid syndromes. Transcriptional profiling of m6A modifications further identified MIS12, for which m6A modifications were reduced in both prematurely senescent hMSCs and METTL3-deficient hMSCs. Knockout of METTL3 accelerated hMSC senescence whereas overexpression of METTL3 rescued the senescent phenotypes. Mechanistically, loss of m6A modifications accelerated the turnover and decreased the expression of MIS12 mRNA while knockout of MIS12 accelerated cellular senescence. Furthermore, m6A reader IGF2BP2 was identified as a key player in recognizing and stabilizing m6A-modified MIS12 mRNA. Taken together, we discovered that METTL3 alleviates hMSC senescence through m6A modification-dependent stabilization of the MIS12 transcript, representing a novel epitranscriptional mechanism in premature stem cell senescence.

Increased chromosomal instability characterizes metastatic renal cell carcinoma

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The clonal origin and parallel evolution of the metastatic lesions and primary tumour.

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The evolutionary branches of primary and metastatic clones diverge early in the development of the tumour.

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Increased genome instability and specific enriched somatic copy number alteration (SCNAs) in metastatic lesions compared to primary tumour.

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LOH at 14q, loss of 14q32.31 and gain of 6p22.2 are highly selected events during metastatic evolution.

The evolutionary trajectories of treatment-naïve metastatic tumour are largely unknown. Such knowledge is crucial for cancer prevention and therapeutic interventions. Herein, we performed whole genome or exome sequencing of 19 tumour specimens and 8 matched normal kidney tissues from 8 clear cell renal cell carcinoma (ccRCC) patients.

The clonal origin and parallel evolution of the metastatic lesions and primary tumour is identified in all 8 patients. But the evolutionary branches of primary and metastatic clones diverge early in the development of the tumour. More importantly, larger scale genomic aberrations including somatic copy number alteration (SCNA) or loss of heterozygosity (LOH) differentiate the metastasis lesions from primary tumour. Based on it, we identify that LOH at 14q, loss of 14q32.31 and gain of 6p22.2 are highly selected events during metastatic evolution. Further functional validations of multiple genes within the SCNA regions indicated that these selected events interact to drive metastatic risk with potential therapeutic relevance. Collectively, we described increased genome instability in metastatic ccRCC and validated it via molecular biology, providing an evolution pattern which may facilitate the translation of basic finding.

Urothelial Carcinoma Detection Based on Copy Number Profiles of Urinary Cell-Free DNA by Shallow Whole-Genome Sequencing

BACKGROUND

Current noninvasive assays for urothelial carcinoma (UC) lack clinical sensitivity and specificity. Given the utility of plasma cell-free DNA (cfDNA) biomarkers, the development of urinary cfDNA biomarkers may improve the diagnostic sensitivity.

METHODS

We assessed copy number alterations (CNAs) by shallow genome-wide sequencing of urinary cfDNA in 95 cancer-free individuals and 65 patients with UC, 58 with kidney cancer, and 45 with prostate cancer. We used a support vector machine to develop a diagnostic classifier based on CNA profiles to detect UC (UCdetector). The model was further validated in an independent cohort (52 patients). Genome sequencing data of tumor specimens from 90 upper tract urothelial cancers (UTUCs) and CNA data for 410 urothelial carcinomas of bladder (UCBs) from The Cancer Genome Atlas were used to validate the classifier. Genome sequencing data for urine sediment from 32 patients with UC were compared with cfDNA. To monitor the treatment efficacy, we collected cfDNA from 7 posttreatment patients.

RESULTS

Urinary cfDNA was a more sensitive alternative to urinary sediment. The UCdetector could detect UC at a median clinical sensitivity of 86.5% and specificity of 94.7%. UCdetector performed well in an independent validation data set. Notably, the CNA features selected by UCdetector were specific markers for both UTUC and UCB. Moreover, CNA changes in cfDNA were consistent with the treatment effects. Meanwhile, the same strategy could localize genitourinary cancers to tissue of origin in 70.1% of patients.

CONCLUSIONS

Our findings underscore the potential utility of urinary cfDNA CNA profiles as a basis for noninvasive UC detection and surveillance.

Aristolochic acid mutational signature defines the low-risk subtype in upper tract urothelial carcinoma

Rationale: Dietary exposure to aristolochic acids and similar compounds (collectively, AA) is a significant risk factor for nephropathy and subsequent upper tract urothelial carcinoma (UTUC). East Asian populations, who have a high prevalence of UTUC, have an unusual genome-wide AA-induced mutational pattern (COSMIC signature 22). Integrating mutational signature analysis with clinicopathological information may demonstrate great potential for risk ranking this UTUC subtype.

Methods: We performed whole-genome sequencing (WGS) on 90 UTUC Chinese patients to extract mutational signatures. Genome sequencing data for urinary cell-free DNA from 26 UTUC patients were utilized to noninvasively identify the mutational signatures. Genome sequencing for primary tumors on 8 out of 26 patients was also performed. Metastasis-free survival (MFS) and cancer-specific survival (CSS) were measured using Kaplan-Meier methods.

Results: Data analysis showed that a substantial proportion of patients harbored the AA mutational signature and were associated with AA-containing herbal drug intake, female gender, poor renal function, and multifocality. Field cancerization was found to partially contribute to multifocality. Nevertheless, AA Sig subtype UTUC patients exhibited favorable outcomes of CSS and MFS compared to the No-AA Sig subtype. Additionally, AA Sig subtype patients showed a higher tumor mutation burden, higher numbers of predicted neoantigens, and infiltrating lymphocytes, suggesting the potential for immunotherapy. We also confirmed the AA signature in AA-treated human renal tubular HK-2 cells. Notably, the AA subtype could be ascertained using a clinically applicable sequencing strategy (low coverage) in both primary tumors and urinary cell-free DNA as a basis for therapy selection.

Conclusion: The AA mutational signature as a screening tool defines low-risk UTUC with therapeutic relevance. The AA mutational signature, as a molecular prognostic marker using either ureteroscopy and/or urinary cell-free DNA, is especially useful for diagnostic uncertainty when kidney-sparing treatment and/or immune checkpoint inhibitor therapy were considered.

A tumor suppressor enhancing module orchestrated by GATA4 denotes a therapeutic opportunity for GATA4 deficient HCC patients

Rationale: Effective targeting therapies are limited in Hepatocellular carcinoma (HCC) clinic. Characterization of tumor suppressor genes (TSGs) and elucidation their signaling cascades could shed light on new strategies for developing targeting therapies for HCC.

Methods: We checked genome-wide DNA copy number variation (CNV) of HCC samples, focusing on deleted genes for TSG candidates. Clinical data, in vitro and in vivo data were collected to validate the tumor suppressor functions.

Results: Focal deletion of GATA4 gene locus was the most prominent feature across all liver cancer samples. Ectopic expression of GATA4 resulted in senescence of HCC cell lines. Mechanistically, GATA4 exerted tumor suppressive role by orchestrating the assembly of a tumor suppressor enhancing module: GATA4 directly bound and potently inhibited the mRNA transcription activity of β-catenin; meanwhile, β-catenin was recruited by GATA4 to promoter regions and facilitated transcription of GATA4 target genes, which were TSGs per se. Expression of GATA4 was effective to shrink GATA4-deficient HCC tumors in vivo. We also showed that β-catenin inhibitor was capable of shrinking GATA4-deficient tumors.

Conclusions: Our study unveiled a previously unnoticed tumor suppressor enhancing module assembled by ectopically expressed GATA4 in HCC cells and denoted a therapeutic opportunity for GATA4 deficient HCC patients. Our study also presented an interesting case that an oncogenic transcription factor conditionally functioned as a tumor suppressor when recruited by a TSG transcription factor.

Evolutionary transition between invertebrates and vertebrates via methylation reprogramming in embryogenesis

Major evolutionary transitions are enigmas, and the most notable enigma is between invertebrates and vertebrates, with numerous spectacular innovations. To search for the molecular connections involved, we asked whether global epigenetic changes may offer a clue by surveying the inheritance and reprogramming of parental DNA methylation across metazoans. We focused on gametes and early embryos, where the methylomes are known to evolve divergently between fish and mammals. Here, we find that methylome reprogramming during embryogenesis occurs neither in pre-bilaterians such as cnidarians nor in protostomes such as insects, but clearly presents in deuterostomes such as echinoderms and invertebrate chordates, and then becomes more evident in vertebrates. Functional association analysis suggests that DNA methylation reprogramming is associated with development, reproduction and adaptive immunity for vertebrates, but not for invertebrates. Interestingly, the single HOX cluster of invertebrates maintains unmethylated status in all stages examined. In contrast, the multiple HOX clusters show dramatic dynamics of DNA methylation during vertebrate embryogenesis. Notably, the methylation dynamics of HOX clusters are associated with their spatiotemporal expression in mammals. Our study reveals that DNA methylation reprogramming has evolved dramatically during animal evolution, especially after the evolutionary transitions from invertebrates to vertebrates, and then to mammals.

Distal regulatory elements identified by methylation and hydroxymethylation haplotype blocks from mouse brain

Background

5-Hydroxymethylcytosine (5hmC) is an oxidation product of 5-methylcytosine (5mC), and adjacent CpG sites in mammalian genome can be co-methylated and co-hydroxymethylated due to the processivity of DNMT and TET enzymes.

Results

We applied TAB-seq and oxBS-seq to selectively detect 5hmC and 5mC at base resolution in the mouse cortex, olfactory bulb and cerebellum tissues. We found that majority of the called 5hmC CpG sites frequently have 5mC modification simultaneously and are enriched in gene body regions of neuron development-related genes in brain tissues. Strikingly, by a systematic search of regions that show highly coordinated methylation and hydroxymethylation (MHBs and hMHBs), we found that MHBs significantly overlapped with hMHBs in gene body regions. Moreover, using a metric called methylation haplotype load, we defined a subset of 1361 tissue-specific MHBs and 3818 shared MHBs. Shared MHBs with low MHL correspond with developmental enhancers, and tissue-specific MHBs resemble the regulatory elements for tissue identity.

Conclusions

Our results provide new insights into the role of coordinately oxidized 5mC to 5hmC as distal regulatory elements may involve in regulating tissue identity.

Electronic supplementary material

The online version of this article (10.1186/s13072-018-0248-3) contains supplementary material, which is available to authorized users.

Aristolochic acid containing herbs induce gender-related oncological differences in upper tract urothelial carcinoma patients

Background

In China, upper tract urothelial carcinoma (UTUC) is less prevalent but more malignant in males. This study investigates the prognostic factors and causes of gender-based differences in Chinese populations.

Methods

Between 1999 and 2011, 687 UTUC patients who underwent surgery were utilized for this study. We evaluated the differences in oncological characteristics, epigenetic biomarkers, cancer-specific survival (CSS), bladder recurrence (BR) rate, and contralateral upper tract recurrence (CUTR) rate. Smoking history, benzene exposure history, and the history of using aristolochic acid (AA) containing herbs were analyzed in detail.

Results

Compared with male patients, female patients showed poorer renal function, lower proportions of tumor stage III/IV, and smaller tumor diameters. The CSS in male patients was lower than that in female patients. Significant gender-related differences were observed concerning various prognostic factors. In female patients, poorer survival rates were attributed to the primary tumor location in the ureter, large diameter primary tumors, severe chronic kidney disease, papillary tumor architecture, high tumor stages, positive N status, and methylated ABCC6 promoters. In male patients, older age, ipsilateral hydronephrosis, large tumor diameters, sessile tumor architecture, high tumor stages, and methylated TMEFF2 promoters were associated with higher cancer-specific mortality. AA might be the main cause of these gender-based differences. The AA-induced UTUC patients presented smaller tumor diameters, lower tumor stages, fewer positive N statuses, more multifocal tumors, lower methylation indices, and poorer renal function. Although AA-induced UTUC patients exhibited better survival rates, BR and CUTR rates were significantly worse.

Conclusion

In China, there exist significant AA-induced differences between male and female UTUC patients. The bladders and contralateral upper urinary tracts of AA-induced UTUC patients should be carefully monitored after surgery.

Diagnostic and prognostic biomarkers of common urological cancers based on aberrant DNA methylation

AIM

We intended to construct DNA methylation-based models for the diagnosis and prognosis of three common urological cancers including prostate adenocarcinoma, renal clear cell carcinoma and bladder urothelial carcinoma.

MATERIALS & METHODS

Total 450K methylation array data from the cancer genome atlas and gene expression omnibus datasets were downloaded. Moderated t-statistics and least absolute shrinkage and selection operator method were used to build diagnosis and prognosis models.

RESULTS

Our diagnostic panels including 128 CpG sites had high sensitivity and accuracy in distinguishing samples and could identify lymphatic metastases in prostate adenocarcinoma patients. The prognostic models with 19 CpG sites for renal clear cell carcinoma and 21 CpG sites for bladder urothelial carcinoma were able to distinguish high- and low-risk patients and improve the predictive ability of the tumor node metastasis staging system.

CONCLUSION

DNA methylation may afford reliable biomarkers in the diagnosis and prognosis of common urological cancers.

Vitamin C increases 5-hydroxymethylcytosine level and inhibits the growth of bladder cancer

Background

5-Hydroxymethylcytosine (5hmC) is converted from 5-methylcytosine (5mC) by a group of enzymes termed ten-eleven translocation (TET) family dioxygenases. The loss of 5hmC has been identified as a hallmark of most types of cancer and is related to tumorigenesis and progression. However, the role of 5hmC in bladder cancer is seldom investigated. Vitamin C was recently reported to induce the generation of 5hmC by acting as a cofactor for TET dioxygenases. In this study, we explored the role of 5hmC in bladder cancer and the therapeutic efficacy of vitamin C in increasing the 5hmC pattern.

Results

5hmC was decreased in bladder cancer samples and was related to patient overall survival. Genome-wide mapping of 5hmC in tumor tissues and vitamin C-treated bladder cancer cells revealed that 5hmC loss was enriched in cancer-related genes and that vitamin C treatment increased 5hmC levels correspondingly. Vitamin C treatment shifted the transcriptome and inhibited the malignant phenotypes associated with bladder cancer cells in both in vitro cell lines and in vivo xenografts.

Conclusions

This study provided mechanistic insights regarding the 5hmC loss in bladder cancer and a rationale for exploring the therapeutic use of vitamin C as a potential epigenetic treatment for bladder cancer.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0527-7) contains supplementary material, which is available to authorized users.

Restoration of 5-hydroxymethylcytosine by ascorbate blocks kidney tumour growth

Loss of 5-hydroxymethylcytosine (5hmC) occurs frequently in a wide variety of tumours, including clear-cell renal cell carcinoma (ccRCC). It remains unknown, however, whether the restoration of 5hmC patterns in tumours could have therapeutic efficacy. Here, we used sodium L-ascorbate (vitamin C, AsANa) and the oxidation-resistant form L-ascorbic acid 2-phosphate sesquimagnesium (APM) for the restoration of 5hmC patterns in ccRCC cells. At physiological concentrations, both show anti-tumour efficacy during long-term treatment in vitro and in vivo Strikingly, global 5hmC patterns in ccRCC cells after treatment resemble those of normal kidney tissue, which is observed also in treated xenograft tumours, and in primary cells from a ccRCC patient. Further, RNA-seq data show that long-term treatment with vitamin C changes the transcriptome of ccRCC cells. Finally, APM treatment induces less non-specific cell damage and shows increased stability in mouse plasma compared to AsANa. Taken together, our study provides proof of concept for an epigenetic differentiation therapy of ccRCC with vitamin C, especially APM, at low doses by 5hmC reprogramming.

Mouse olfactory bulb methylome and hydroxymethylome maps reveal noncanonical active turnover of DNA methylation

Hydroxylation of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) by TET enzymes presents a particular regulatory mechanism in the mammalian brain. However, although methylation and hydroxymethylation of cytosines in non-CpG contexts have been reported, these mechanisms remain poorly understood. Here, we applied TAB-seq and oxBS-seq selectively to detect 5hmC and 5mC at base resolution in olfactory bulb derived from female mice. We found that active turnover of 5mC to 5hmC occurred in both CpG and non-CpG contexts. Strikingly, we identified a different sequence preference for 5mC and 5hmC in a CH context, in which H = A, C, or T, TNCA/TC for 5mC and NNCA/T/CN for 5hmC. More importantly, we found that genes showing 5mC to 5hmC turnover showed only limited overlap in CpG and CH contexts, and that olfactory receptor genes were marked with higher turnover of 5mC to 5hmC in non-CpG context. Collectively, we identified an unexpected sequence preference for non-CpG hydroxymethylation and distinct target genes regulated by the turnover of 5mC to 5hmC in CpG and CH contexts.

BCL6 Antagonizes NOTCH2 to Maintain Survival of Human Follicular Lymphoma Cells

Although the BCL6 transcriptional repressor is frequently expressed in human follicular lymphomas (FL), its biological role in this disease remains unknown. Herein, we comprehensively identify the set of gene promoters directly targeted by BCL6 in primary human FLs. We noted that BCL6 binds and represses NOTCH2 and NOTCH pathway genes. Moreover, BCL6 and NOTCH2 pathway gene expression is inversely correlated in FL. Notably, BCL6 upregulation is associated with repression of NOTCH2 and its target genes in primary human and murine germinal center (GC) cells. Repression of NOTCH2 is an essential function of BCL6 in FL and GC B cells because inducible expression of Notch2 abrogated GC formation in mice and killed FL cells. Indeed, BCL6-targeting compounds or gene silencing leads to the induction of NOTCH2 activity and compromises survival of FL cells, whereas NOTCH2 depletion or pathway antagonists rescue FL cells from such effects. Moreover, BCL6 inhibitors induced NOTCH2 expression and suppressed growth of human FL xenografts in vivo and primary human FL specimens ex vivo These studies suggest that established FLs are thus dependent on BCL6 through its suppression of NOTCH2Significance: We show that human FLs are dependent on BCL6, and primary human FLs can be killed using specific BCL6 inhibitors. Integrative genomics and functional studies of BCL6 in primary FL cells point toward a novel mechanism whereby BCL6 repression of NOTCH2 drives the survival and growth of FL cells as well as GC B cells, which are the FL cell of origin. Cancer Discov; 7(5); 506-21. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 443.

Loss of 5-hydroxymethylcytosine is linked to gene body hypermethylation in kidney cancer

Both 5-methylcytosine (5mC) and its oxidized form 5-hydroxymethylcytosine (5hmC) have been proposed to be involved in tumorigenesis. Because the readout of the broadly used 5mC mapping method, bisulfite sequencing (BS-seq), is the sum of 5mC and 5hmC levels, the 5mC/5hmC patterns and relationship of these two modifications remain poorly understood. By profiling real 5mC (BS-seq corrected by Tet-assisted BS-seq, TAB-seq) and 5hmC (TAB-seq) levels simultaneously at single-nucleotide resolution, we here demonstrate that there is no global loss of 5mC in kidney tumors compared with matched normal tissues. Conversely, 5hmC was globally lost in virtually all kidney tumor tissues. The 5hmC level in tumor tissues is an independent prognostic marker for kidney cancer, with lower levels of 5hmC associated with shorter overall survival. Furthermore, we demonstrated that loss of 5hmC is linked to hypermethylation in tumors compared with matched normal tissues, particularly in gene body regions. Strikingly, gene body hypermethylation was significantly associated with silencing of the tumor-related genes. Downregulation of IDH1 was identified as a mechanism underlying 5hmC loss in kidney cancer. Restoring 5hmC levels attenuated the invasion capacity of tumor cells and suppressed tumor growth in a xenograft model. Collectively, our results demonstrate that loss of 5hmC is both a prognostic marker and an oncogenic event in kidney cancer by remodeling the DNA methylation pattern.

Programming and inheritance of parental DNA methylomes in vertebrates

5-Methylcytosine (5mC) is a major epigenetic modification in animals. The programming and inheritance of parental DNA methylomes ensures the compatibility for totipotency and embryonic development. In vertebrates, the DNA methylomes of sperm and oocyte are significantly different. During early embryogenesis, the paternal and maternal methylomes will reset to the same state. Herein, we focus on recent advances in how offspring obtain the DNA methylation information from parents in vertebrates.

Prognostic and predictive value of epigenetic biomarkers and clinical factors in upper tract urothelial carcinoma

Aim: We conducted this study to identify gene promoter methylation status and clinical predictors for upper tract urothelial carcinoma (UTUC) patients. Materials & methods: Using methylation-sensitive PCR, we examined ten genes promoter methylation status in 687 UTUC patients. Results: A methylated promoter of three genes to predict higher tumor stage (T3 and T4), five genes to predict higher tumor grade (G3) and one gene to predict pN+ were certified in this study. Nine factors were significantly associated with poor cancer-specific survival. Six factors were considered as predictors to develop bladder recurrence after surgery. Conclusion: Methylation occurs commonly in UTUCs, may affect carcinogenic mechanisms, and is a well predictive factor for cancer-specific survival and bladder recurrence in UTUCs.

Contralateral upper tract urothelial carcinoma after nephroureterectomy: the predictive role of DNA methylation

Background

Aberrant methylation of genes is one of the most common epigenetic modifications involved in the development of urothelial carcinoma. However, it is unknown the predictive role of methylation to contralateral new upper tract urothelial carcinoma (UTUC) after radical nephroureterectomy (RNU). We retrospectively investigated the predictive role of DNA methylation and other clinicopathological factors in the contralateral upper tract urothelial carcinoma (UTUC) recurrence after radical nephroureterectomy (RNU) in a large single-center cohort of patients.

Methods

In a retrospective design, methylation of 10 genes was analyzed on tumor specimens belonging to 664 consecutive patients treated by RNU for primary UTUC. Median follow-up was 48 mo (range: 3–144 mo). Gene methylation was accessed by methylation-sensitive polymerase chain reaction, and we calculated the methylation index (MI), a reflection of the extent of methylation. The log-rank test and Cox regression were used to identify the predictor of contralateral UTUC recurrence.

Results

Thirty (4.5%) patients developed a subsequent contralateral UTUC after a median follow-up time of 27.5 (range: 2–139) months. Promoter methylation for at least one gene promoter locus was present in 88.9% of UTUC. Fewer methylation and lower MI (P = 0.001) were seen in the tumors with contralateral UTUC recurrence than the tumors without contralateral recurrence. High MI (P = 0.007) was significantly correlated with poor cancer-specific survival. Multivariate analysis indicated that unmethylated RASSF1A (P = 0.039), lack of bladder recurrence prior to contralateral UTUC (P = 0.009), history of renal transplantation (P < 0.001), and preoperative renal insufficiency (P = 0.002) are independent risk factors for contralateral UTUC recurrence after RNU.

Conclusions

Our data suggest a potential role of DNA methylation in predicting contralateral UTUC recurrence after RNU. Such information could help identify patients at high risk of new contralateral UTUC recurrence after RNU who need close surveillance during follow up.

Programming and inheritance of parental DNA methylomes in mammals

The reprogramming of parental methylomes is essential for embryonic development. In mammals, paternal 5-methylcytosines (5mCs) have been proposed to be actively converted to oxidized bases. These paternal oxidized bases and maternal 5mCs are believed to be passively diluted by cell divisions. By generating single-base resolution, allele-specific DNA methylomes from mouse gametes, early embryos, and primordial germ cell (PGC), as well as single-base-resolution maps of oxidized cytosine bases for early embryos, we report the existence of 5hmC and 5fC in both maternal and paternal genomes and find that 5mC or its oxidized derivatives, at the majority of demethylated CpGs, are converted to unmodified cytosines independent of passive dilution from gametes to four-cell embryos. Therefore, we conclude that paternal methylome and at least a significant proportion of maternal methylome go through active demethylation during embryonic development. Additionally, all the known imprinting control regions (ICRs) were classified into germ-line or somatic ICRs.