"Cancer researchers have debated whether shortened telomeres were a cause or effect of tumors," says Alan K. Meeker, Ph.D., lead author of the study and a postdoctoral fellow in urology and pathology at Hopkins. "What our study suggests is that telomere dysfunction may be a key component in the development of many epithelial cancers, those that arise from tissues lining our organs."
Studying tissue taken from small precancerous lesions in the bladder, esophagus, large intestine, mouth and cervix, the research team found abnormal telomere lengths in 97 percent of the cases examined. In particular, abnormally short telomeres were found in 88 percent of cases.
"We were surprised how often you see shortened telomeres this early in the development of these cancers," says Meeker. "It's a strong indicator that abnormal telomeres are likely playing a causal role in cancer development."
Telomeres cap the chromosome ends, protecting the interior, gene-containing parts of the chromosome from being accidentally lost. As normal cells divide and age, some of the telomere DNA is lost, and the telomeres get progressively shorter. Normal cells monitor the lengths of their telomeres and initiate cell suicide or halt cell division when telomeres get too short. Other researchers have shown in mice that cancer, which is characterized principally by unrestricted cell growth and lack of cell death, can occur if this monitoring system breaks down, leading to the development of chromosomal abnormalities.
"It appears that the telomere shortening frequently observed in large advanced tumors has already occurred before it can be detected by standard diagnostic tools, when cellular changes characteristi
Contact: Vanessa Wasta
Johns Hopkins Medical Institutions