Night shifts and cancer

A team of researchers from the Arts and Sciences at Texas A&M University (United States) has discovered that disruption of circadian rhythms It weakens immune defenses and promotes the appearance of more aggressive breast cancer.

The study, published in the journal Nature Oncogenhas consisted of the analysis of two genetically modified model groups that develop aggressive breast cancerin which one group lived with a normal day and night schedule, and the other lived with an altered light cycle that altered their internal clocks.

Typical models ended up developing cancer around week 22while the group with circadian alteration showed signs of cancer much earlieralmost at 18 weeks. In this group, the tumors have been much more aggressive and have had a greater chance of spread to the lungsan indicator of poor outcomes in breast cancer patients.

Furthermore, the alteration of the internal clock of each model ended up suppressing immune defenses, creating a more favorable environment for cancer growth.

“It wasn’t just that the tumors grew faster (…) The immune system was actively slowed down, creating more favorable conditions for cancer cells survive and spread“said the director of the study, Dr. Tapasree Roy Sarkar.

Afterwards, he detailed that the effects have not been limited to tumors, but that the alteration of circadian rhythms also ended up modifying the composition of healthy breast tissue, making it more vulnerable to cancer.

An “off switch” for the immune system

“We observed clear changes in the morphology of the mammary glands, the milk-producing tissue of the breast,” said Sarkar, who has revealed the discovery of a molecule, the leukocyte immunoglobulin-like receptor B4 (LILRB4), which can act as an “off switch” for the immune system.

Although LILRB4 It helps prevent excessive inflammation and protect healthy tissue. Under normal conditions, researchers have discovered that in cancer it can overexploit its activity and become dangerous.

“LILRB4 acts as an immune checkpoint (…) By acting on LILRB4, the tumor microenvironment became less immunosuppressiveand even in altered circadian conditions, we observed less spread of cancer,” he added.

For all these reasons, the deactivation of this immune checkpoint has allowed us to restore the immune system’s ability to defend itself, suggesting a new therapeutic angle to treat aggressive breast cancers linked to circadian alterations.

“Cancer marks time (…) If your internal clock is altered, cancer takes advantage, but now we have found a new way to combat it,” Sarkar stressed.

By experimentally linking the circadian alterations With the progression of breast cancer, the study opens new doors to therapies aimed at patients whose lifestyles or occupations place them at chronic circadian risk.

All of this is of special importance if we take into account that the world “works 24 hours a day” and that there is a part of the population that works at night or in rotating shifts, so it is “fundamental” to understand the impact of circadian alterations on cancer risk.

“Our next goal is to better understand how we can reverse the effects of circadian disruption and help improve human health with real-world impact,” Sarkar concluded.