Timing is everything or so the saying goes. This always seems obvious in fields like music, business or sports but not as much in the field of Oncology. That is why the results of a recent paper published in Nature Communication are all the more surprising. Research has shown that cancer cells grow faster at night when we’re resting.
This understanding is extremely important as it opens a completely new direction of research for cancer treatment optimization.
These findings arose out of an investigation into the relationships between different receptors in the cell – a complex network that we still do not completely understand. The receptors – protein molecules on the cell’s surface or within cells – take in biochemical messages secreted by other cells and pass them on into the cell’s interior.
The scientists, led by Dr. Mattia Lauriola, a postdoctoral fellow in the research group of Prof. Yosef Yarden of the Weizmann Institute’s Biological Regulation Department, working together with Prof. Eytan Domany of the Physics of Complex Systems Department, focused on two particular receptors.
The first, the epidermal growth factor receptor, EGFR, promotes the growth and migration of cells, including cancer cells. The second binds to a steroid hormone called a glucocorticoid (GC). Glucocorticoids play a role in maintaining the body’s energy levels during the day, as well as the metabolic exchange of materials. It is often called the stress hormone because its levels rise in stressful situations, rapidly bringing the body to a state of full alert. Tests found that cell growth was decreased when the GC receptor is bound to its steroid messenger.
Since the steroid levels peak during waking hours and drop off during sleep, the scientists asked how this might affect the second receptor – EGFR. Checking the levels of this activity in mice, they found that there was a significant difference: This receptor is much more active during sleep and quiescent during waking hours.
This information was immediately applied to a clinical trial using mice models of cancer. Lapatinib, a new generation cancer drug was administered to daytime and nighttime groups. The results revealed significant differences between the sizes of tumors in the different groups of mice, depending on whether they had been given the drug during sleep or waking hours.
The experimental findings suggest that it is indeed the rise and fall in the levels of the GC steroids over the course of 24 hours that hinder or enable the growth of the cancer.
“It seems to be an issue of timing,” says Yarden. “Cancer treatments are often administered in the daytime, just when the patient’s body is suppressing the spread of the cancer on its own. What we propose is not a new treatment, but rather a new treatment schedule for some of the current drugs.”