Postdoctoral student Silke Kiessling and McGill Psychiatry Professor Dr. Nicholas Cermakian conducted a study out of the Douglas Mental Health Institute to better understand how people’s biological clocks affect cancer cells. Specifically, they examined whether cancer cells’ growth can be inhibited by targeting the biological clock.
The study was published in the journal BMC Biology in February. It was based on a simple question: If the circadian rhythm of a tumour cell is fixed, will it slow its growth?
Tumour cells are different from healthy cells because their growth is unconstrained. Most healthy cells consistently divide every 24 hours due to their circadian clock. Also known as the “biological clock,” the circadian clock governs the body’s sleep-wake cycle, as well as regulating many physiological processes. The circadian clock can influence how and at what speed cells divide. Cancer gives rise to daughter cells in a way that’s not controlled.
This is the first study to show that the development of a tumour cell is remarkably slowed when its biological clock is targeted. The first experiments to prove the hypothesis took approximately a year and a half to complete, but the follow-up experiments to disprove that other variables might be affecting the results took over three years.
“[There were] many experiments to rule out other explanations,” Cermakian explained.
Previous research has shown that a circadian disruption in an individual, such as a shift worker, can increase his or her risk of cancer. When the researchers discovered that there was a correlation between the circadian clock and tumour growth, they wanted to understand how to inhibit that growth.
The research team worked with skin cells and colon tumours in mice and activated the circadian clock in these cells to compare cell cycle gene expression, cell cycle phase distribution, and tumour growth.
Cermakian emphasized that this experiment will affect cancer treatments by, hopefully, leading to preventative therapies and giving patients more time to fight the disease.
“You, me, and everyone in the population have disturbed rhythms,” Cermakian said.
While nobody’s circadian clock is perfect, this insight could lead to new targets for cancer treatment.
Now that there is a proven link between circadian rhythm hygiene and cancer risk, the hope is that the general population will do more to prioritize regulating their sleep-wake cycle.
The next step for this study is to see how the treatments used on cells in mice could be applied to humans, but it will take many more experiments before the researchers can get to that stage.
In the meantime, there are steps everyone can take to improve their circadian rhythm hygiene. Often, the first step is following the advice parents have told their kids for years, such as maintaining a uniform eating schedule, limiting screen time before bed, and sleeping at night as opposed to taking naps during the day.
