Alternative lengthening of telomeres (ALT) process. When a cancer cell’s DNA breaks, the cell triggers DNA repair and helper proteins to attach to the damaged stretch of DNA and stretch it out, allowing it to search and capture complementary sequences of telomere DNA to use as a template for repair. (Credit: N. W. Cho et al./Cell)
On Sept. 23, KurzweilAI noted that scientists at the Salk Institute had discovered an on-and-off “switch” in cells that might allow for increasing telomerase, which rebuilds telomeres at the ends of chromosomes to keep cells dividing and generating.
We also noted that cancer cells hijack this process and that the scientists expect that the “off” switch might help keep telomerase activity below this threshold.
Now in another study published last week in Cell, Roger Greenberg, MD, PhD, associate professor of Cancer Biology in the Perelman School of Medicine at the University of Pennsylvania and his colleagues describe their discovery of a second method used by cancer cells to survive, involving a DNA-repair-based mechanism called “alternative lengthening of telomeres” (ALT).
The researchers found that approximately 15 percent of cancers use the ALT process for telomere lengthening, but that some cancer types use ALT up to 40 to 50 percent of the time./.../
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