since moved to the National University of Singapore.">

Is cancer more active at night?

By Steve Pointing 07/10/2014


An interesting new study in cell biology indicates a steroid hormone responsible for keeping us alert during the day may also suppress the spread of cancer cells.  This highlights that cancer therapy may benefit from timing to coincide with when the body is least able to defend against cancer at night. The work appears in the prestigious journal Nature Communications (http://www.nature.com/ncomms/2014/141003/ncomms6073/full/ncomms6073.html). 

The discovery arose form a study on how cells communicate:  Our cells have receptors on their outer surface (usually proteins) and these recognise external chemical “messages” and pass them on to the cell’s interior.  One receptor named epidermal growth factor (EGFR) signals growth and migration of cells and this includes cancer cells.  Another binds to the steroid hormone glucocorticoid (GC) that is important in regulating our “energy” levels during the day (it is also sometimes called the stress hormone, because its level is elevated under stress).  A team at the Weisman Institute in Israel demonstrated that messages from these receptors to the cell have a hierarchy and some take precedence over others.  In particular the EGFR is suppressed when the GC receptor is bound to the steroid hormone messenger – and since GC hormone levels peak in daytime they reasoned that at night the reverse would occur and EGFR activation would be elevated.  Experiments on mice showed this was indeed the case, with elevated EGFR levels during sleep and “quiet” times of the day.  The implication is that at night the body may inadvertently provide a more favourable environment for proliferation of cancer cells, and so therapeutic regimes may benefit from being adjusted to take account of this.