For the study, published in the May 15 issue of the journal Clinical Cancer Research, Meeker, De Marzo and colleagues used a technique called fluorescent in situ hybridization (FISH) to compare telomere length in cells from both precancerous lesions and normal surrounding cells of the bladder, esophagus, large intestine, mouth and cervix.
The FISH test uses fluorescent-labeled probes specific for particular locations in DNA and is commonly used to detect or confirm gene or chromosome abnormalities. Chromosomal DNA is first denatured, a process that separates the strands within the DNA's double helix structure. The Hopkins scientists then added a fluorescent probe specific for telomere regions. As the DNA re-forms into a double helix, it blends with the fluorescent molecules, enabling scientists to examine specific chromosomal locations under a microscope for the level of fluorescence that corresponds to telomere length.
Not all precancerous epithethial lesions are capable of fully advancing to malignant cancers, Meeker says. One reason for this may be that if genetic instability gets too high, the cells die, thus blocking cancer progression. Only cells that find a way to balance their telomere length - allowing unlimited cell division and a limited degree of genomic stabilization - can progress to becoming an invasive, life-threatening tumor.
The Hopkins research team examined 35 precancerous lesions from 25 patients, inclu
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Contact: Vanessa Wasta
wastava@jhmi.edu
410-955-1287
Johns Hopkins Medical Institutions
26-May-2004