|
New telomere discovery could help explain why cancer cells never stop dividing
October 05, 2007A group working at the Swiss Institute for Experimental Cancer Research (ISREC) in collaboration with the University of Pavia has discovered that telomeres, the repeated DNA-protein complexes at the end of chromosomes that progressively shorten every time a cell divides, also contain RNA. This discovery, published online October 4 in Science Express, calls into question our understanding of how telomeres function, and may provide a new avenue of attack for stopping telomere renewal in cancer cells.
Inside the cell nucleus, all our genetic information is located on twisted, double stranded molecules of DNA which are packaged into chromosomes. At the end of these chromosomes are telomeres, zones of repeated chains of DNA that are often compared to the plastic tips on shoelaces because they prevent chromosomes from fraying, and thus genetic information from getting scrambled when cells divide. The telomere is like a cellular clock, because every time a cell divides, the telomere shortens. After a cell has grown and divided a few dozen times, the telomeres turn on an alarm system that prevents further division. If this clock doesn't function right, cells either end up with damaged chromosomes or they become "immortal" and continue dividing endlessly - either way it's bad news and leads to cancer or disease. Understanding how telomeres function, and how this function can potentially be manipulated, is thus extremely important.
The DNA in the chromosome acts like a sort of instruction manual for the cell. Genetic information is transcribed into segments of RNA that then go out into the cell and carry out a variety of tasks such as making proteins, catalyzing chemical reactions, or fulfilling structural roles. It was thought that telomeres were "silent" - that their DNA was not transcribed into strands of RNA. The researchers have turned this theory on its head by discovering telomeric RNA and showing that this RNA is transcribed from DNA on the telomere.
Why is this important" In embryonic cells (and some stem cells), an enzyme called telomerase rebuilds the telomere so that the cells can keep dividing. Over time, this telomerase dwindles and eventually the telomere shortens and the cell becomes inactive. In cancer cells, the telomerase enzyme keeps rebuilding telomeres long past the cell's normal lifetime. The cells become "immortal", endlessly dividing, resulting in a tumor. Researchers estimate that telomere maintenance activity occurs in about 90% of human cancers. But the mechanism by which this maintenance takes place is not well understood. The researchers discovered that the RNA in the telomere is regulated by a protein in the telomerase enzyme. Their discovery may thus uncover key elements of telomere function.
"It's too early to give yet a definitive answer," to whether this could lead to new cancer therapies, notes Joachim Lingner, senior author on the paper. "But the experiments published in the paper suggest that telomeric RNA may provide a new target to attack telomere function in cancer cells to stop their growth."
Ecole Polytechnique Fédérale de Lausanne
Why is this important" In embryonic cells (and some stem cells), an enzyme called telomerase rebuilds the telomere so that the cells can keep dividing. Over time, this telomerase dwindles and eventually the telomere shortens and the cell becomes inactive. In cancer cells, the telomerase enzyme keeps rebuilding telomeres long past the cell's normal lifetime. The cells become "immortal", endlessly dividing, resulting in a tumor. Researchers estimate that telomere maintenance activity occurs in about 90% of human cancers. But the mechanism by which this maintenance takes place is not well understood. The researchers discovered that the RNA in the telomere is regulated by a protein in the telomerase enzyme. Their discovery may thus uncover key elements of telomere function.
"It's too early to give yet a definitive answer," to whether this could lead to new cancer therapies, notes Joachim Lingner, senior author on the paper. "But the experiments published in the paper suggest that telomeric RNA may provide a new target to attack telomere function in cancer cells to stop their growth."
Ecole Polytechnique Fédérale de Lausanne
Telomere News and Current Telomere Events RSSUGA researchers discover mechanism that explains how cancer enzyme winds up on ends of chromosomes
Human cancer cells divide and conquer. Unless physicians can control that division with surgery, chemotherapy or radiation, the wildly dividing cells will eventually destroy a person's life.
Evolution of human genome's 'guardian' gives people unique protections from DNA damage
Human evolution has created enhancements in key genes connected to the p53 regulatory network - the so-called guardian of the genome - by creating additional safeguards in human genes to boost the network's ability to guard against DNA damage that could cause cancer or a variety of genetic diseases.
Baumann lab identifies elusive telomere RNA subunit in single cell model
The Stowers Institute's Baumann Lab has identified the long-sought telomerase RNA gene in a single-cell research model. Their findings have been posted to the Web site of the journal Nature Structural & Molecular Biology and will appear in a future print edition.
Hotspots found for chromosome gene swapping
Crossovers and double-strand DNA breaks do not occur randomly on yeast chromosomes during meiosis, but are greatly influenced by the proximity of the chromosome's telomere, according to research in the laboratory of Whitehead Fellow Andreas Hochwagen.
Could vitamin D, a key milk nutrient, affect how you age?
There is a new reason for the 76 million baby boomers to grab a glass of milk. Vitamin D, a key nutrient in milk, could have aging benefits linked to reduced inflammation, according to a new study published in the American Journal of Clinical Nutrition.
Mayo Clinic study points to a possible biomarker for colon cancer in people 50 and under
An abnormality of chromosomes long associated with diseases of aging has, for the first time, been linked to colon cancer in people 50 years old and younger, an age group usually considered young for this disease.
Investigators uncover intriguing clues to why persistent acid reflux sometimes turns into cancer
New research from scientists at UT Southwestern Medical Center and the Dallas Veterans Affairs Medical Center underscores the importance of preventing recurring acid reflux while also uncovering tantalizing clues on how typical acid reflux can turn potentially cancerous.
Exploring the Dark Matter of the Genome
Not so long ago, the difficult-to-sequence, highly repetitive, gene-poor DNA found in regions of chromosomes known as heterochromatin was called "junk." Like dark matter in the universe, the true nature of heterochromatin was unknown.
New genetic biomarkers could predict coronary heart disease
New genetic markers may be able to predict whether a person is likely to have coronary heart disease (CAD) in the future. Research carried out by Dr. M. Balasubramanyam and Dr.V.Mohan at the Madras Diabetes Research Foundation (India) shows that people who are pre-diabetic or who have Type 2 diabetes have much shorter telomeres1 and, since these people are prone to CAD, an early test could indicate their susceptibility and help them to alter their lifestyle to avoid or delay the onset of the disease.
Gene mutations linked to hereditary lung disease
Scientists at Johns Hopkins have identified the genetic culprits that trigger a hereditary form of a fatal lung disease. The findings, published in the March 29, 2007 issue of the New England Journal of Medicine, may provide new directions in diagnosis and treatment for families that inherit genes for the disease, as well as for those that develop non-inherited forms of the illness.
More Telomere News Articles
| © 2008 BrightSurf.com |