A new study clarifies the link between disruption of the circadian rhythm, our internal biological clock, and the development of cancer, in this case of the lung. Explanations.
- Almost all of the body’s functions depend on the 24-hour circadian rhythm, and this clock is synchronized primarily through natural light. Disorders of this rhythm can have consequences on sleep, metabolism, the cardiovascular and immune systems, mood, memory, etc.
- Workers, soldiers, care professions, security… In France, 4.3 million people work at night, that is to say between midnight and five o’clock in the morning, according to the Labor Code.
Night work, staggered hours, sleep time amputated by screens… It’s not easy today to take care of your circadian rhythm, this biological clock defined by the alternation between wakefulness and sleep on a 24-hour cycle. . And yet, everything should encourage us to do so, because the disruption of this rhythm can expose people to various health problems, such as sleeping troublesa weight gaineven the Alzheimer’s disease. It could even be, according to the World Health Organization, a probable carcinogen. But why ? If the link between the biological clock and cancers was poorly understood until now, a new study from the University of La Jolla in California (United States) sheds some light on us.
Mice exposed to a dysregulated circadian rhythm
As part of their work, recently published in the journal Science Advances, the researchers studied mouse models expressing the Kras gene which, when mutated, is involved in the onset of lung cancer – among other things. A first group of rodents was exposed to a healthy circadian rhythm, ie a regular alternation of 12 hours of light and 12 hours of darkness. The mice of the second group were subjected to an irregular rhythm supposed to resemble that experienced by workers with staggered hours (the “3X8” for example), in short to a kind of permanent jet-lag.
After 25 weeks, the researchers found that in the “jet-lagged” mice, expression of the Kras gene jumped 68% compared to those following a regular circadian rhythm. Specifically, the number of tumors in their lung tissue was much higher. How to explain it?
A link to body temperature
According to scientists, the link between dysregulated rhythm and lung cancer could be associated with changes in body temperature. More specifically to the HSF1 protein (heat shock factor 1), essential for gene regulation, particularly in the event of stress – which, let us remember, is a consequence of a disruption of the circadian rhythm. “Normally, our body temperature changes a degree or two while we sleep. If shift workers do not experience this normal drop, it could interfere with the normal functioning of HSF1, and ultimately lead to more dysregulation in the body”and therefore the onset of cancer, explains Professor Katja Lamia, co-author of the study, in a communicated.
The good news is that it may soon be possible to target HSF1 with drug treatment, in order to detect tumors early in people whose biological clocks are chronically disrupted, and thus increase the chances of survival.
This is not the first time that research has linked cancer to dysregulation of the circadian rhythm. Previous studies, validated by Insermhave shown that a regularly upset clock, like that of night workers, notably favors the appearance of breast cancer or prostate.