Working night shifts associated with cancer cases’ increase

Working night shifts disrupts the body’s circadian rhythm, which a number of studies have found may raise the risk of cancer development. Now, researchers have shed light on the mechanisms behind this association.

Researchers have shed light on how shift work may increase cancer risk.

Scientists from the Massachusetts Institute of Technology (MIT), United States (U.S.), reveal that disruption to the circadian rhythm also leads to the impairment of two tumor suppressor genes, which can spur tumor growth.

Lead author Thales Papagiannakopoulos, of MIT’s Koch Institute for Integrative Cancer Research, and colleagues publish their findings in the journal Cell Metabolism.

A study reported by Medical News Today last year, for example, found a link between rotating night shift work and increased risk of death from cardiovascular disease, lung cancer, and all causes.

Shift work interferes with the body’s circadian rhythm – the approximate 24-hour cycle that regulates when we go to sleep and when we wake up, primarily in response to light and dark in the environment.

The body’s central circadian rhythm, or “master clock,” is made up of around 20,000 nerve cells in the brain, which are collectively referred to as the suprachiasmatic nucleus (SCN).

Situated in the hypothalamus, the SCN receives information about light and dark levels from the retina of the eyes, and this information is sent to the body’s cells.

Papagiannakopoulos and colleagues describe two genes within cells that play a role in circadian clock regulation: Bmal1 and Per2.

Bmal1 is responsible for activating Per2. Upon activation, Per2 switches on a number of biological processes regulated by circadian rhythm, including cell division and metabolism, which the team points out are two hallmarks of cancer.

The researchers note that the proteins encoded by these genes usually fluctuate throughout the day, but these fluctuations diminish if light and dark cycles are disrupted.