Keep the tumor warm
In conditions of low ambient temperature, all warm-blooded people have a hard time. When the body cools, blood vessels contract to retain heat in vital organs, while some parts of the body, such as fingers and toes, suffer. To combat the cold, the intensity of metabolic processes increases and shivers appear. Further cooling reduces the efficiency of cell functioning and slows down all processes in the body. The body falls into a state of cold stress, in which only the most important organs, such as the brain, retain functionality.
Researchers at the Institute of Oncology in Rosewell Park, Buffalo, working under the leadership of Elizabeth Repasky, argue that the low ambient temperature is fraught with another danger. It changes the nature of the growth and movement of malignant cells, at least in the body of mice. Among other things, this fact raises interesting questions about the use of mice as an animal model when studying the effectiveness of antitumor therapy methods and the behavior of tumors in a living organism.
The experiments carried out by the authors showed that when kept at a relatively room temperature comfortable for humans – about 22 ° C – mice have a faster and more aggressive growth of malignant tumors compared to animals living at a higher temperature comfortable for mice – about 30 °C.
In experiments, the cool ambient temperature stimulated the growth of various types of tumors, including breast, skin, colon and pancreatic cancers. Moreover, the cool temperature accelerated the growth of tumors even in cases where animals were kept in similar conditions throughout their lives before the onset of the disease.
The main component of the antitumor immune response is tumor-specific T-lymphocytes, which recognize cancer cells by the abnormal proteins they express and destroy them. As a rule, tumors respond to this by releasing molecular signals that cause the body to suppress the activity of the immune system. This confrontation continues until one of the parties takes over. The action of a number of antitumor drugs used in the clinic is aimed at shifting this balance towards the immune system.
At the beginning of the experiment, the blood of healthy mice contained in different temperature conditions had the same number of tumor-specific T-lymphocytes. However, the T-cells of the animals contained in the heat found the tumor faster and penetrated it more efficiently. They also secreted more humoral components of antitumor immunity than the cells of mice kept at cool temperatures. In addition, the tumors of the latter contained more suppressor cells that suppress immune responses. Based on these observations, the researchers concluded that cooling shifts the body's response to the tumor towards the formation of tolerance to it.
Most vivariums are guided by the same recommendations for keeping animals, according to which mice are kept at a temperature below comfortable for them. This fact may be the cause of a systemic error in the study of diseases and methods of their treatment in mouse models. For example, attempts to stimulate immunity in conditions when it is initially suppressed can lead to false results.
If healthy mice have a choice of temperature conditions, they move to places where the temperature is maintained at a comfortable 30 ° C. Mice with malignant tumors behave differently – they choose hot compartments of the enclosure with a temperature of about 38 °C. Patients with oncological diseases also often complain of severe chills, especially after the introduction of antitumor drugs.
The authors suggest that growing tumors can induce cold stress to ensure their own survival. The mechanisms of this phenomenon are still unclear, but their interpretation can help to increase the effectiveness of antitumor therapy.
Small clinical studies have already been conducted that have demonstrated that a moderate increase in body temperature for several hours increases the response of breast cancer, angiosarcoma and sarcoma to radiotherapy. However, without conducting large-scale clinical trials, it is impossible to draw final conclusions.
Article by Kathleen M. Kokolus et al. Baseline tumor growth and immune control in laboratory mice are significantly influenced by subthermoneutral housing temperature published in the journal Proceedings of the National Academy of Sciences.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of The Conversation:
Chilly temperatures help cancers grow.
21.11.2013