Cancer researchers are eying to unlock the cellular-level function of the telomerase enzyme, which is linked to the disease's growth.
The latest findings by the researchers at the UT Southwestern Medical Center demonstrated that telomerase repairs chromosomes in one of two ways - depending on whether a cell is dividing normally or if the cell is under stress from enzyme inhibition - and could lead to new or improved cancer-fighting therapies that promote inhibition of this enzyme.
The number of times a cell divides is determined by telomeres, protective caps on the ends of chromosomes that indicate cell age. Every time a cell divides, the telomeres shorten. When telomeres shrink to a certain length, the cell either dies or stops dividing. In cancer cells, the enzyme telomerase keeps rebuilding the telomeres, so the cell never receives the cue to stop dividing.
Although telomerase was discovered in 1985, exactly how this enzyme repairs telomeres to enable cancer cells to divide and grow was largely unknown. Until now, researchers didn't know how many telomerase molecules went into action at the telomeres and under what conditions.
"It's a single molecule under normal cancer growth conditions, but if you shorten telomeres artificially by inhibiting telomerase, now it's more than one molecule acting on the ends of the telomeres," said Dr. Woodring Wright, professor of cell biology and senior author of the study.
When acting as a single molecule at the telomeres, telomerase adds about 60 nucleotide molecules "in one fell swoop to the end of the chromosome," Wright added.
Researchers also discovered that structures in cells called Cajal bodies help process telomerase during chromosome-repair activity. Cajal bodies assemble ribonucleic acid (RNA) within proteins.
"Telomerase uses this RNA in order to add the sequences onto the end, and this complex is assembled or modified in some way in these Cajal bodies," said Wright.
The study has been published in Molecular Cell.