Key cause of cancer

  • Asian News International, PTI, Washington
  • |
  • Updated: May 28, 2004 12:35 IST

A new study conducted by scientists at the Johns Hopkins Kimmel Cancer Center has revealed that abnormally short telomeres play a role in the early development of many types of cancer.

According to Alan K. Meeker, lead author of the study "Cancer researchers have debated whether shortened telomeres were a cause or effect of tumors. 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."

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.

According to Angelo M. De Marzo, senior author of the study "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 characteristic of early precancer can only be seen through a microscope by a pathologist."

"Therefore, intervention strategies aimed at preventing, or even reversing, telomere shortening may be effective in lowering cancer incidence. And assessing telomere length may provide a new direction for cancer prevention studies, and lead to improved early diagnosis of precancerous lesions," he said.

The Hopkins research team examined 35 precancerous lesions from 25 patients, including 11 lesions from eight bladders, three lesions from three uterine cervixes, seven lesions from five large intestines, six lesions from three esophagi and eight lesions from six mouths. They scored the telomere lengths on a five-point scale ranging from very short to very long.

Telomere length abnormalities were found in 34 of 35 lesions studied. Short or very short telomeres were observed in all lesions of the esophagus, large intestine and uterine cervix, in eight of 11 lesions of the bladder and seven of eight lesions of the oral cavity. Ten of 35 (29 per   cent) lesions, particularly those of the bladder, displayed a variety of telomere lengths.


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