Iron deficiency in the lungs may reduce the risk of lung cancer in old age.
The probability of cancer increases with age: medical statistics say that the majority of cancer patients are people in their sixth or seventh decade. Mutations are considered a prerequisite for cancer (although there are some reservations here), and in this case it is clear why age is a risk factor: the longer you live, the greater the chance that a malignant mutation will get into your DNA.
But the same statistics show that after eighty years, malignant tumors (at least some of them) occur much less frequently. On the one hand, this can be explained by the fact that those who live to old age have had well-functioning anti-cancer mechanisms throughout their lives and for whom they have not stopped functioning well with age. On the other hand, it may also be that extreme old age itself becomes an anti-tumor factor. Malignant tumors grow in a certain environment, on which they largely depend, and if the body is already very old, the tumor will find itself in an uncomfortable environment. In addition, uncontrolled malignant division can be an unbearable burden for a cell that has discovered the corresponding mutations in itself.
Stanford University researchers experimented with mice whose lung cells were supplied with oncogenic mutations using a genetic editor. The gene with the mutations was silent for a while, and could be turned on at the researchers’ discretion (before it was turned on, another gene performed the required function). Accordingly, the mutated gene was either activated in young mice or the mice were first allowed to age. It turned out that tumors formed more often in young mice and were larger in size than in old mice.
Cancer cells are usually inhibited by specific genes; in an experiment, they can be deliberately switched off to increase the likelihood of tumors. More than two dozen such genes were switched off in young and old mice. In general, tumors began to grow faster in both groups, but in young mice, they appeared again more often and were also larger than in old mice with the same mutations. From this, we can conclude that old mice had something that additionally inhibited the disease even with the anti-tumor genes switched off.
Other researchers at Memorial Sloan Kettering Cancer Center have found that as we age, lung cells increase their production of a protein called NUPR1, which affects iron metabolism. The more NUPR1 there is, the less iron the cell has to use for anything. And since iron is needed, among other things, for cell division, its deficiency should curb tumor growth. When old mice have the gene No. 1 turned off, their iron levels jumped noticeably, and at the same time, the mice began to develop lung tumors more often. The NUPR1 protein is found not only in the lungs of mice, but also in the lungs of people, and the researchers also found that people over eighty have significantly more of it than people under fifty-five.
It should be clarified here that both articles published on the portal for now bioRxivthat is, they await peer review before being published in a scientific journal, and at the peer review stage, some significant shortcomings may be discovered. Also, we should not forget about the difference between experimental mice and people: in mice, experimental cancer develops due to mutations introduced into the genome artificially, while in humans, the tumor occurs naturally due to mutations that have accumulated throughout life. That is, it would be necessary to check whether the iron-related mechanism works in the case of natural human tumors. And it would also be good to check – both in mice and in people – what age-limiting mechanisms begin to work in the case of tumors of other types, not only lung ones.
In general, some researchers have doubts about the very existence of an age-related cancer limiter in very old people. Some experts They saythat this phenomenon is the result of diagnostic peculiarities. In people over a certain age, malignant tumors are diagnosed less often, not because they do not have them, but because at that age they either neglect going to the doctor or have other, more obvious health problems. True, lung cancer will still be an exception here – its probability really does decrease in old age, even when the above-mentioned objections are taken into account. So, as far as lung tumors are concerned, it makes sense to study the age-related mysteries further.
Source: www.nkj.ru
