Corporate Banner
Satellite Banner
Pharma Outsourcing
Scientific Community
 
Become a Member | Sign in
Home>News>This Article
  News
Return

Tissue of Origin Determines Cancer-associated CpG Island Promoter Hypermethylation Patterns

Published: Friday, October 05, 2012
Last Updated: Friday, October 05, 2012
Bookmark and Share
Meehan, Sproul and co-workers conclude that general aberrant promoter hypermethylation in cancer does not promote tumorigenesis, but instead reinforces transcription repression inherited from pre-cancerous tissue.

It has been proposed that DNA methylation of tumour suppressor genes is a key event in carcinogenesis, driving cells to become cancer cells. In previous work (PMID: 21368160), the authors could not identify de novo methylated genes in breast cancer that fitted with this view. Instead they implicated aberrant DNA methylation as a marker of cell lineage rather than tumour progression.  In most cases, DNA methylation did not appear to cause the repression with which it is associated. In their present work they extended this observation to 6 additional tumour types. Their recent analysis supports the view that the bulk of aberrant promoter hypermethylation in cancer occurs predominantly at genes that are repressed in pre-cancerous tissue and therefore does not directly contribute to tumour progression by silencing tumour suppressor genes. This epigenetic alteration is common to all the cancer types, but does not result in a universal set of methylated genes, implying that a common mechanism is responsible for promoter hypermethylation at distinct sets of repressed genes in different cancers. Future research in this field should, therefore, focus on confirming whether aberrant hypermethylation does directly suppress rare ‘driver’ genes and if the mechanism responsible for driver gene suppression is the same or different to that acting at already repressed target genes.

This study contributes to the provocative question list raised by the National Cancer Institute (http://provocativequestions.nci.nih.gov/rfa). Specifically question, PQB – 2; As we improve methods to identify epigenetic changes that occur during tumor development, can we develop approaches to discriminate between "driver" and "passenger" epigenetic events?

-------------------------------------------------------------------------------------------------------------------------
Author list: Duncan Sproul, Robert R Kitchen, Colm E Nestor, J Michael Dixon, Andrew H Sims, David J Harrison, Bernard H Ramsahoye and Richard R Meehan

Title : Tissue of origin determines cancer-associated CpG island promoter hypermethylation patterns

Journal: Genome Biology


 
Summary

Background

Aberrant CpG island promoter DNA hypermethylation is frequently observed in cancer and is believed to contribute to tumor progression by silencing the expression of tumor suppressor genes. Previously, we observed that promoter hypermethylation in breast cancer reflects cell lineage rather than tumor progression and occurs at genes that are already repressed in a lineage-specific manner. To investigate the generality of our observation we analyzed the methylation profiles of 1,154 cancers from 7 different tissue types.

Results

We find that 1,009 genes are prone to hypermethylation in these 7 types of cancer. Nearly half of these genes varied in their susceptibility to hypermethylation between different cancer types. We show that the expression status of hypermethylation prone genes in the originator tissue determines their propensity to become hypermethylated in cancer; specifically, genes that are normally repressed in a tissue are prone to hypermethylation in cancers derived from that tissue. We also show that the promoter regions of hypermethylation-prone genes are depleted of repetitive elements and that DNA sequence around the same promoters is evolutionarily conserved. We propose that these two characteristics reflect tissue-specific gene promoter architecture regulating the expression of these hypermethylation prone genes in normal tissues.

Conclusions

As aberrantly hypermethylated genes are already repressed in pre-cancerous tissue, we suggest that their hypermethylation does not directly contribute to cancer development via silencing. Instead aberrant hypermethylation reflects developmental history and the perturbation of epigenetic mechanisms maintaining these repressed promoters in a hypomethylated state in normal cells. 


Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,500+ scientific posters on ePosters
  • More than 3,700+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Defending Ourselves by Keeping ‘Junk DNA’ Quiet
By genome-wide mapping in two mutant cell lines, the Meehan lab shows that loss of DNA methylation is coincident with specific activation of the IAP endogenous retroposon and the appearance of virus like particles.
Wednesday, January 01, 2014
Unanticipated Consequences of DNA Hypomethylation; Loss and Gain of Polycomb Mediated Transcription Repression in Somatic Cells
By genome-wide mapping of the Polycomb Repressive Complex 2 (PRC2)-signature histone mark, H3K27me3, in DNA methylation-deficient mouse somatic cells, the Meehan lab shows that loss of DNA methylation is coincident with widespread H3K27me3 redistribution.
Monday, April 01, 2013
Non-Genotoxic Carcinogen Exposure Induces Defined Changes in the 5-Hydroxymethylome
In a genome wide study Meehan, Moggs and MARCAR co-authors examined 5mC and 5hmC profiles of liver in control and phenobarbital treated mice. They observe dynamic and reciprocal changes in the 5mC/5hmC patterns over genes promoters that are transcriptionally up-regulated.
Friday, October 05, 2012
Coupling Genome Defence to Epigenetic Reprogramming
The work, just published in Development, identifies genes DIRECTLY regulated by DNA methylation.
Thursday, September 06, 2012
Scientific News
Immunotherapy Agent Benefits Patients with Drug-Resistant Multiple Myeloma in First Human Trial
Daratumumab proved generally safe in patients, even at the highest doses.
NIH Study Shows No Benefit of Omega-3 Supplements for Cognitive Decline
Research was published in the Journal of the American Medical Association.
NIH Launches Human RSV Study
Study aims to understand infection in healthy adults to aid development of RSV medicines, vaccines.
Computerized Flexible Needles Prove Themselves in Biological Tissue
The advantage of the system is that you can avoid obstacles with the needles or critical tissues and that the system during the insertion of the needle in real time can adjust the path if, for example, the tissue deforms.
DARWIN 2 24-week Monotherapy Data in RA Confirm Previous Results
Safety profile in DARWIN 2 consistent with previous filgotinib RA studies.
Researchers Publish Landmark “Basket Study”
Researchers from Memorial Sloan Kettering Cancer Center (MSK) have announced results from the first published basket study, a new form of clinical trial design that explores responses to drugs based on the specific mutations in patients’ tumors rather than where their cancer originated.
Agricultural Intervention Improves HIV Outcomes
A multifaceted farming intervention can reduce food insecurity while improving HIV outcomes in patients in Kenya, according to a randomized, controlled trial led by researchers at UC San Francisco.
Overdose of Vitamin D in Teenagers May Lead to Increased Cholesterol Levels
Dosing obese teens with vitamin D shows no benefits for their heart health or diabetes risk, and could have the unintended consequences of increasing cholesterol and fat-storing triglycerides. These are the latest findings in a series of Mayo Clinic studies in childhood obesity.
Phase 2 Trials Underway for New Single Dose Malaria Treatment
The new drug, which prevents the malaria parasite from reproducing and spreading, is now undergoing Phase II clinical trials in humans.
Promising Drug for Parkinson's Disease
A drug which has already been in use for decades to treat liver disease could be an effective treatment to slow down progression of Parkinson’s disease, scientists from the University of Sheffield have discovered.
Scroll Up
Scroll Down
SELECTBIO

Skyscraper Banner
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,500+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,700+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FREE!