Cancer therapies are typically administered during the daytime. But according to a new paper published in the journal Nature Communications, cancer's growth is actually suppressed by the body's natural hormones during the day. It's nighttime, the researchers think, when cancers do most of their growing, which means that changing the timing of treatments such as chemo could boost their efficacy.
Researchers from the Weizmann Institute of Science stumbled across this surprising finding while researching cell receptor proteins, including one that interacts with glucocorticoid, a chemical that plays a role in maintaining the body's alertness throughout the day, the researchers explained in a release. Glucocorticoid ensures we have enough energy to function while we're awake, and when we encounter stressful situations, it surges through our system to help us prepare for potential danger.
The authors of the study discovered that, when glucocorticoid binds to receptors on the outside of cells, it blocks the ability of another chemical, the epidermal growth factor receptor (EGFR), from doing so. This is significant because EGFR has been implicated in cancer, including in fueling the growth and migration of malignant cells, the researchers said.
The researchers confirmed in mice that EGFR is significantly more active at night than during the day, when glucocorticoid blocks its activity. When they gave breast cancer model mice a new drug designed to treat that disease, the animals responded differently to the treatment depending on the time of day that they received their dose. Those that took the meds at night developed significantly smaller tumors.
The researchers believe this finding could have relevance for human cancer patients. "Cancer treatments are often administered in the daytime, just when the patient's body is suppressing the spread of the cancer on its own," they said in the release. "What we propose is not a new treatment, but rather a new treatment schedule for some of the current drugs."