Medical Science

How telomeres and mitochondria protect us from cancer

Coordinated alarm response triggers self-destruction of old, cancer-prone cells

Together against cancer: If an aging cell threatens to degenerate, a multi-stage alarm reaction ensures the timely destruction of the affected cell – and thus counteracts the development of cancer. Telomeres, the end caps of the chromosomes, and mitochondria, the cell power plants, are involved in this signaling pathway, as researchers report in “Nature”. This finding sheds new light on cellular protective mechanisms against cancer and could help clarify why this protection sometimes fails.

At the ends of our chromosomes, the so-called telomeres form protective caps that stabilize our genetic material. As the cells age, these protective DNA sequences become shorter and shorter, until a crisis finally occurs: the cells that have become genetically unstable initiate apoptosis , a cellular suicide program. This marks them as “for disposal” to the immune system and at the same time destroys the cell from the inside out. This mechanism prevents the development of cancer.

Here the telomeres (green) of chromosomes are highlighted by green fluorescent markers.© Salk Institute

protective response against cancer

So far, however, it was unknown how the process works in detail and how some cells can escape death and form tumors. A team led by Joe Nassour from the Salk Institute for Biological Studies in La Jolla, California, has now dealt with this. “Our results demonstrate a synergy between critically short telomeres, mitochondria, and the innate immune system that evolved to prevent age-related cancer development in humans,” the authors report.

With the help of genetic screenings on human fibroblasts, i.e. cells of the connective tissue, Nassour and his colleagues found that telomeres that have become too short activate signaling pathways of the innate immune system that are decisive for cell death during the crisis. In doing so, they rely on the help of the mitochondria, the power plants of the cell.

Communication between telomeres and mitochondria

“We were thrilled when we discovered that telomeres communicate with mitochondria,” says Nassour’s colleague Jan Karlseder. It is only when the ends of the chromosomes work together with the cell power plants that cellular processes are set in motion that kill defective and thus potentially degenerating cells. As long as this signaling pathway works, it can also protect against cancer in old age.

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