and Medicine for Seniors
Cancer Grows at Night, Maybe That’s
When to Attack, New Study Says
Weizmann Institute scientists find
that a hormone that keeps us alert also suppresses the spread of cancer
Oct. 6, 2015 - They emerge at
night, while we sleep unaware, growing and spreading out as quickly as
they can. And they are deadly. In a surprise
finding that was recently published in Nature
Communications, Weizmann Institute of Science researchers showed
that nighttime is the right time for cancer to grow and spread in the
body. Their findings suggest that administering certain treatments in
time with the body’s day-night cycle could boost their efficiency.
This finding 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.
With multiple receptors, the cell
receives all sorts of messages at once, and some of these messages can
take precedence over others. In the experiment, Lauriola and Yarden
found that cell migration – the activity promoted by the EGF receptor –
is suppressed 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.
How relevant are these findings for
cancers, particularly those which use the EGF receptors to grow and
spread? To find out, the scientists gave Lapatinib – one of the new
generation of cancer drugs – to mouse models of cancer. This drug, used
to treat breast cancer, is designed to inhibit EGFR, and thus to prevent
the growth and migration of the cancer cells.
In the experiment, they gave the
mice the drug at different times of day. 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.
The conclusion, say the
scientists, is that it could be more efficient to administer certain
anticancer drugs at night.
“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.”
Domany's research is supported by the Leir Charitable Foundations;
Mordechai Segal, Israel; and the Louis and Fannie Tolz Collaborative
Research Project. Prof. Domany is the incumbent of the Henry J. Leir
Yarden’s research is supported by the Dr. Miriam and Sheldon G. Adelson
Medical Research Foundation; the Maurice and Vivienne Wohl Biology
Endowment; the Louis and Fannie Tolz Collaborative Research Project; the
European Research Council; and the Marvin Tanner Laboratory for Research
on Cancer. Prof. Yarden is the incumbent of the Harold and Zelda
Goldenberg Professorial Chair in Molecular Cell Biology.
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