Aging And DNA Methylation In Alu And LINE-1 Repeated Elements

An age-related decrease in DNA methylation, the process whereby genes are shut off and chromosomes packed up in complex strictures, could potentially lead to cancer development, according to researchers.


When a person does not have a proper rate of DNA methylation, chromosomes and DNA sequences become unstable, and therefore are more likely to contribute to cancer.


Approximately 55 percent of the human genome consists of repetitive elements, including approximately 500,000 long interspersed nucleotide elements (LINE) and 1.5 million repetitive elements of the Alu DNA sequences. Typically, these sequences undergo heavy methylation.


Previous human studies have linked a lack of methylation among LINE and Alu repetitive elements with disease. However, whether the unsteadiness of these elements is unrestrained with age had not yet been established.


For the current study, researchers from the Center of Molecular and Genetic Epidemiology at the University of Milan in Italy, in collaboration with investigators at the Harvard School of Public Health, Boston, MAmeasured DNA levels in 693 patients. Patients gave up to three blood samples, taken approximately three years apart from each other.


Overall, the older a patient grew, the less likely these elements were to methylate. Specifically, researchers found a 0.016 percent decrease for LINE-1 elements and a 0.015 percent decrease for Alu repetitive elements for each year of increased age.


"Such age-related decrease in methylation may increase the risk of mutational events potentially leading to cancer," said lead author Laura Cantone, a researcher at the University of Milan.


Aging and DNA methylation in Alu and LINE-1 repeated elements

Abstract 557


This was presented at the 2008 Annual Meeting of the American Association for Cancer Research.


The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes nearly 27,000 basic, translational, and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and more than 70 other countries. AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants. The AACR Annual Meeting attracts more than 17,000 participants who share the latest discoveries and developments in the field. Special Conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment, and patient care. AACR publishes five major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. Its most recent publication and its sixth major journal, Cancer Prevention Research, is the only journal worldwide dedicated exclusively to cancer prevention, from preclinical research to clinical trials. The AACR also publishes CR, a magazine for cancer survivors, patient advocates, their families, physicians, and scientists. CR provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship, and advocacy.


American Association for Cancer Research