Cancer risk decreases with age for this reason, study finds
The risk of cancer decreases after age 80 according to a new study. For their report, an international team of scientists studied lung cancer in mice by observing the behavior of alveolar type 2 (AT2) stem cells. These are cells essential for lung regeneration and the starting point of many lung cancers.
The role of NUPR1 protein in aging
Researchers discovered a high concentration of the NUPR1 protein in aged mice. The protein causes cellular behavior that simulates iron deficiency and therefore limits the regeneration of cells, even cancerous ones.
“Aging cells actually contain more iron, but for reasons that are still poorly understood, they function as if they lack it.”explains Xueqian Zhuang, a cancer biologist at Memorial Sloan Kettering Cancer Center in New York. “Aged cells lose their capacity for renewal and therefore uncontrolled proliferation characteristic of cancer.”
The mechanism has been observed in human cells: the increase in NUPR1 protein causes a decrease in iron available to cells. Researchers found that artificially reducing the NUPR1 protein or artificially increasing iron restores cell growth capabilities.
The researchers' discovery opens new therapeutic perspectives by targeting iron metabolism in the elderly. It could also help restore lung capacity in patients affected by the long-term effects of COVID-19.
But that's not all since the study explains that this discovery has important implications for anticancer treatments based on ferroptosis, a form of cell death triggered by iron. This cell death is less common in aged cells due to their functional iron deficiency. Result: they are potentially more resistant to treatments in development based on ferroptosis.
New anticancer therapeutic avenues
“In terms of cancer prevention, our data suggest that events occurring during youth are likely to be much more dangerous than those occurring later.”underlines Tuomas Tammela, cancer biologist at MSK. “So preventing smoking, UV exposure, or other obvious carcinogenic exposures in young people is probably even more important than we thought.”
Many aspects of the role of the NUPR1 protein and its influence on stem cell functions remain to be explored. But these results are very important for the fight against cancer at all ages. Xueqian Zhuang recalls that“There is still much unknown about how aging actually changes cancer biology.”
The effectiveness of treatments will depend on their ability to take into account different variables: type and stage of cancer, associated medical conditions and, as this study demonstrates, age of the patient.
