Telomeres Linked to Cancer Growth and Aging

Shortened telomere length may help inhibit cancer, but it is also associated with the progression of aging in humans.

Researchers at Johns Hopkins University are closer to understanding cancer growth and aging thanks to the discovery of molecular evidence that shows how a biochemical process controls the lengths of protective chromosome tips.

The study was conducted by biologist David C. Zappulla and graduate student Evan P. Hass. The pair showed how in baker’s yeast cells, 2 proteins work together to usher a key enzyme to the chromosome tip, the telomere, which restores its length and diminishes with each round of cell division.

The enzyme, telomerase, is not found abundantly in adult human tissue, but is found in larger amounts in cancers and allows unlimited cell growth. The model yeasts have linear chromosomes like humans, and the scientists’ work aimed to find out how telomerase works in hopes of ultimately learning how to disrupt it and possibly kill cancer cells.

"While inhibiting telomerase could prove effective in stopping disease, the downside exists in the fact that shortened telomere length is associated with the progression of aging in humans and many other animals,” Zappulla said. “This means that while telomerase could be inhibited to slow disease progression, it could also be encouraged to slow aging. That, however, could run the risk of triggering cancer, as cancer and aging have almost a yin-yang relationship.”

The finding also confirms previous findings and provides new insights about 2 key proteins, Ku and Sir4. Earlier studies showed that Ku binds to Sir4, and the present researchers proved that that binding action is significant for telomerase to lengthen telomeres.

The workings of the new telomerase-regulating protein network could be understood more deeply by studying its effects on a single telomere in real time, Zappulla explained. The lab is currently in the process of developing an experimental system in the baker’s yeast as the next phase of this molecular biology research.

Baker’s yeast cells divide rapidly and working on the yeast rather than human cells allows the scientists to control all variables. Scientists acknowledge the limitations in only studying yeast cells, and wonder about the relevance these findings will have to humans.

Future studies will involve investigating if a similar mechanism operates in human cells, which could potentially yield a basis for new drugs to treat cancer.