Project description:Genome wide DNA methylation profiling of normal and tumor prostate samples, as well as cultured primary prostate cells overexpressing DNA Methyltransferases (DNMTs) and EZH2 Candidate gene based studies have identified a handful of aberrant CpG DNA methylation events in prostate cancer. However, DNA methylation profiles have not been compared on a large scale between prostate tumor and normal prostate, and the mechanisms behind these alterations are unknown. In this study, we quantitatively profiled 95 primary prostate tumors and 86 healthy prostate tissue samples for their DNA methylation levels at 26,333 CpGs representing 14,104 gene promoters by using the Illumina HumanMethylation27 platform. A 2-class Significance Analysis of this dataset revealed 5,912 CpG sites with increased DNA methylation and 2,151 CpG sites with decreased DNA methylation in tumors (FDR < 0.8%). Prediction Analysis of this dataset identified 87 CpGs that are the most predictive diagnostic methylation biomarkers of prostate cancer. By integrating available clinical follow-up data, we also identified 69 prognostic DNA methylation alterations that correlate with biochemical recurrence of the tumor. To identify the mechanisms responsible for these genome-wide DNA methylation alterations, we measured the gene expression levels of several DNA methyltransferases (DNMTs) and their interacting proteins by TaqMan qPCR and observed increased expression of DNMT3A2, DNMT3B, and EZH2 in tumors. Subsequent transient transfection assays in cultured primary prostate cells revealed that DNMT3B1 and DNMT3B2 overexpression resulted in increased methylation of a substantial subset of CpG sites that also showed tumor-specific increased methylation. Bisulfite converted DNA from 193 samples were hybridized to the Illumina Infinium 27k Human Methylation Beadchip v1.2. The tissue samples (first 181) and the cultured cell samples (last 12) were normalized independently.
Project description:Genome wide DNA methylation profiling of normal and tumor prostate samples, as well as cultured primary prostate cells overexpressing DNA Methyltransferases (DNMTs) and EZH2 Candidate gene based studies have identified a handful of aberrant CpG DNA methylation events in prostate cancer. However, DNA methylation profiles have not been compared on a large scale between prostate tumor and normal prostate, and the mechanisms behind these alterations are unknown. In this study, we quantitatively profiled 95 primary prostate tumors and 86 healthy prostate tissue samples for their DNA methylation levels at 26,333 CpGs representing 14,104 gene promoters by using the Illumina HumanMethylation27 platform. A 2-class Significance Analysis of this dataset revealed 5,912 CpG sites with increased DNA methylation and 2,151 CpG sites with decreased DNA methylation in tumors (FDR < 0.8%). Prediction Analysis of this dataset identified 87 CpGs that are the most predictive diagnostic methylation biomarkers of prostate cancer. By integrating available clinical follow-up data, we also identified 69 prognostic DNA methylation alterations that correlate with biochemical recurrence of the tumor. To identify the mechanisms responsible for these genome-wide DNA methylation alterations, we measured the gene expression levels of several DNA methyltransferases (DNMTs) and their interacting proteins by TaqMan qPCR and observed increased expression of DNMT3A2, DNMT3B, and EZH2 in tumors. Subsequent transient transfection assays in cultured primary prostate cells revealed that DNMT3B1 and DNMT3B2 overexpression resulted in increased methylation of a substantial subset of CpG sites that also showed tumor-specific increased methylation.
Project description:The aim of this study was to analyze critically the potential usefulness of selected DNA methylation biomarkers in supporting conventional histological diagnostic tests for PCa. The selection of potential biomarkers was conducted by microarray profiling of DNA methylation on prostate tissues extracted from the gland after total radical prostatectomy. DNA methylation profiles of 16 prostate samples without carcinoma and 16 matched pairs of samples with and without cancer cells isolated from prostates containing prostate carcinoma
Project description:Cancer is characterised by DNA hypermethylation and gene silencing of CpG island-associated promoters, including tumour suppressor genes The methyl-CpG-binding domain (MBD) family of proteins bind to methylated DNA and can aid in the meditation of gene silencing by interaction with histone deacetylases and histone methyltransferases. However the mechanisms responsible for eliciting CpG island hypermethylation in cancer, and the potential role that MBD may proteins play in modulation of the methylome remain unclear. Our previous work demonstrated that MBD2 preferentially binds to the hypermethylated GSTP1 promoter CpG island in prostate cancer cells. Here, we use functional genetic approaches to investigate if MBD2 plays an active role in promoting DNA methylation. First, we show that loss of MBD2 results in inhibition of both maintenance and spread of de novo methylation of a transfected construct containing the GSTP1 promoter CpG island in prostate cancer cells and Mbd2-/- mouse fibroblasts. De novo methylation was rescued by transient expression of Mbd2 in Mbd2-/- cells. Second, we show that MBD2 depletion triggers significant hypomethylation genome-wide in prostate cancer cells with concomitant loss of MBD2 binding at promoter and enhancer regulatory regions. Finally, CpG islands and shores that become hypomethylated after MBD2 depletion in LNCaP cancer cells show significant hypermethylation in clinical prostate cancer, highlighting a potential active role of MBD2 in promoting cancer specific hypermethylation. Importantly, co-immunoprecipiation of MBD2 reveals that MBD2 associates with DNA methyltransferase (DNMT) enzymes 1 and 3A. Together our results demonstrate that MBD2 plays a critical role in â??rewritingâ?? the cancer methylome at specific regulatory regions. LNCaP prostate cancer cell line clones with reduced MBD2 expression were establised by using shRNA to MBD2 and scrambled control clones were established with scrambled control shRNA. To interrogate methylation changes induced by MBD2 knock-down we profiled three stably transfected scrambled control clones and three MBD2 knockdown clones on Illumina HumanMethylation450K arrays. Differential methylation analysis was carried out to identified CpG sites hypo-/hyper-methylated as a result of MBD2 knockdown.
Project description:Protein arginine methylation is an important process, which regulates diverse cellular functions including cell proliferation, RNA stability, DNA repair and gene transcription. Based on literature search, protein arginine methyltransferase (PRMT) indeed plays important roles in colon cancer pathophysiology. The PRMT expression level is involved in colon cancer patient’s survival and has been suggested to be a prognostic marker in colon cancer patients. Recently, our group found a novel methylation on epidermal growth factor receptor (EGFR), which affected EGFR downstream signaling. investigators further observed the methylation event on EGFR not only regulated tumor growth in mouse xenograft model but also influenced cetuximab response in colon cancer cell lines. To further study the clinical correlation between EGFR methylation and cetuximab response, we propose to detect EGFR methylation level in paraffin embedded tissue samples from colorectal cancer patients with or without cetuximab treatment by IHC staining and analyze its correlation with cetuximab response. This study will provide an insight to the strategy of colorectal cancer therapy.
Project description:Cancer is characterised by DNA hypermethylation and gene silencing of CpG island-associated promoters, including tumour suppressor genes The methyl-CpG-binding domain (MBD) family of proteins bind to methylated DNA and can aid in the meditation of gene silencing by interaction with histone deacetylases and histone methyltransferases. However the mechanisms responsible for eliciting CpG island hypermethylation in cancer, and the potential role that MBD may proteins play in modulation of the methylome remain unclear. Our previous work demonstrated that MBD2 preferentially binds to the hypermethylated GSTP1 promoter CpG island in prostate cancer cells. Here, we use functional genetic approaches to investigate if MBD2 plays an active role in promoting DNA methylation. First, we show that loss of MBD2 results in inhibition of both maintenance and spread of de novo methylation of a transfected construct containing the GSTP1 promoter CpG island in prostate cancer cells and Mbd2-/- mouse fibroblasts. De novo methylation was rescued by transient expression of Mbd2 in Mbd2-/- cells. Second, we show that MBD2 depletion triggers significant hypomethylation genome-wide in prostate cancer cells with concomitant loss of MBD2 binding at promoter and enhancer regulatory regions. Finally, CpG islands and shores that become hypomethylated after MBD2 depletion in LNCaP cancer cells show significant hypermethylation in clinical prostate cancer, highlighting a potential active role of MBD2 in promoting cancer specific hypermethylation. Importantly, co-immunoprecipiation of MBD2 reveals that MBD2 associates with DNA methyltransferase (DNMT) enzymes 1 and 3A. Together our results demonstrate that MBD2 plays a critical role in ârewritingâ the cancer methylome at specific regulatory regions. LNCaP prostate cancer cell line clones with reduced MBD2 expression were establised by using shRNA to MBD2 and scrambled control clones were established with scrambled control shRNA. To interrogate expression changes induced by MBD2 knock-down we profiled three stably transfected scrambled control clones and three MBD2 knockdown clones on Affymetrix HuGene 1.0ST expression arrays. Differential expression analysis was carried out to identified genes up-/down-regulated by MBD2 knockdown.
Project description:DNA methylation analysis of paired prostate tumor and noncancerous tissues was perform in order to identify potential DNA methylation biomarkers for prostate cancer diagnostics and prognosis. Based on comparison of tumors versus noncancerous tissues and cases with and without biochemical disease recurrence (BCR), several gene targets were selected for more detailed analysis. Differences in methylation were further confirmed by means of methylation-specific PCR and significantly correlated with gene expression. Survival analysis indicated various combinations of DNA methylation biomarkers as significant prognosticaters of time to BCR, therefore, showing their potential clinical significance.
Project description:Localized prostate cancer exhibits profound genomic, pathologic, and clinical heterogeneity, and current clinical prognostic factors do not accurately distinguish aggressive from indolent disease for an individual man. We and others have demonstrated that aberrant DNA methylation may be an important driver of aggressive disease. Herein, we analyze the tumor methylomes of 619 localized prostate cancers and assess the interactions between methylation and somatic tumor genomic profiles. We identify three distinct methylation subtypes, including a hypermethylation subtype which is associated with early biochemical recurrence. DNA methylation and gene copy number status synergistically regulate mRNA abundance, and aberrant methylation is strongly associated with common prostate cancer driver aberrations, including mutation density, and with altered RNA abundance profiles. Finally, we identify a set of multivariate methylation biomarkers that are prognostic of rapid biochemical recurrence. Taken together, our data provide the first comprehensive assessment of the interplay between somatic molecular phenotypes and aberrant DNA methylation in localized, non-indolent prostate cancer, and suggest that integrated genome-epigenome analyses may accurately identify men at risk for adverse clinical outcomes in this patient cohort.
Project description:Aging and age-related pathologies including multiple cancer types can be controlled by specifically targeting senescent cells, or more specifically, their hallmark feature, the senescence-associated secretory phenotype (SASP). Lysine methylation is one of the most common histone posttranslational modifications that regulate chromatin structure in mammalian cells. Changes in histone lysine methylation status have been observed during cancer progression, a consequence of dysregulation of histone lysine methyltransferases and/or their opposing demethylases. KDM4 (or JMJD2) encompasses demethylases that target histone H3 on lysines 9 and 36 sites. Frequently overexpressed in breast, colorectal, lung, prostate, and other tumor types and required for efficient cancer cell proliferation, KDM4 proteins represent novel drug targets. However, emerging studies are beginning to uncover the functional roles of KDM4 in epigenomic regulation during cellular senescence and organismal aging, thus providing a new angle to understand human aging and allowing expansion of the existing list of epigenetic targets, the drugs of which are currently limited to the pharmacological arsenal against DNA methyltransferases and histone deacetylases.