One of the symptoms of some cancers is weight loss, which is accompanied by muscle atrophy. According to experts, about 80% of people with cancer suffer from this condition, called cachexia. The body literally eats away at itself until vital organs, such as the heart, begin to fail. Even if a person does not die from cachexia, he or she becomes weaker and sicker, and as a result, tolerates chemotherapy less well. However, the cause of this condition remains a mystery that has not been solved for thousands of years. Therefore, to this day there are no treatments for this disease. Now, a new study gives hope that the situation will change.
Cancer diseases are often accompanied by weight loss
Unreasonable weight loss in cancer
Cachexia has been known since ancient times. Hippocrates described it this way — “The flesh burns and becomes water, the stomach fills with water, the feet and legs swell, the shoulders, collarbones, chest and thighs melt… The disease is fatal.” To shed light on the causes of this condition, researchers at Peking University (PKU) studied the metabolic changes it causes.
The authors studied thousands of metabolites, that is, metabolic products in the blood of healthy mice, and compared them with metabolites in mice suffering from cachexia caused by injection of lung cancer cells. As a result, the researchers found that lactate, a chemical that causes muscle spasms, was elevated in sick rodents. The study authors report this in the journal Nature Metabolism. In their opinion, lactate may play a key role in the disease.
Tissue metabolism changes during cancer
When scientists measured lactate levels in people with cancer , he was also promoted. From this we can conclude that the changes in the metabolism of mice and people with cancer are approximately the same.
Why do people lose weight with cancer
The increased concentration of lactate in mice with cancer did not come as a surprise to scientists. The reason is that tumor metabolism has its own characteristics. The main one is that cancer cells switch to a less efficient way of producing energy. With this metabolism, lactate becomes a waste product, resulting in accumulation.
But does excess lactate really cause cachexia? To find out, the authors of the work implanted lactate pumps into healthy mice, which introduced this substance into the animals' bloodstream. As a result, after just two weeks, the mice lost a large amount of fat and muscle, despite the fact that they did not have cancer and ate the same amount of food as mice from the control group. As the researchers explain, the changes in their body were the same as with cachexia caused by cancer.
Study Finds Lactate Causes Weight Loss
The last question remained unanswered — How does lactate cause the body to lose weight? During the study, scientists discovered that this substance interacts with receptors on cell membranes. At the same time, it causes various effects, including suppression of neuron activity, the formation of blood vessels in tumors, changes in the function of immune cells, etc. Let us recall that with malignant tumors changes in the functioning of the immune system occur, but scientists have recently found a way to deal with this.< /p>
Scientists have suggested that lactate engages one of the receptors, and this causes cachexia. To test their hypothesis, they induced cancer in mice that, through genetic modifications, lacked a lactate receptor on the surface of fat cells called GPR81. As a result, all symptoms of cachexia in rodents were reduced or absent altogether. When the authors of the work removed the GPR81 receptor in mice with cancer, the results were the same.
Most likely, lactate, acting on the receptor, sends a signal that triggers the process of rapid fat burning. As a result, the body begins to waste valuable calories unnecessarily. The fat cells eventually shrivel up like a squished marshmallow. However, it remains a mystery why blocking GPR81 prevents muscle tissue atrophy, since muscle cells do not have this receptor.
Lactate causes the body to quickly burn calories in fat cells. Photo source: actu.epfl.ch
It is too early to draw final conclusions regarding lactate and its role in cachexia, since additional studies, including clinical ones, are needed. However, if scientists’ assumptions are confirmed, the development of an effective method of treating a dangerous disease will remain a matter of time, which means that the survival rate of people with cancer will increase.
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Finally, we note that scientists are also working on other methods of combating cancer. For example, Russian researchers recently announced that they are close to creating a vaccine against cancer. You can read more about this at the link.