Hyderabad, March 29: People, who change their daily routine frequently, are
less susceptible to the killer cancer.
In an interesting study on mouse model, a US team, which included a
Hyderabadi scientist Shobhan Gaddameedhi, has found that disruption of the
biological clock is in fact helpful at least in prevention of cancers, though the
risk of obesity and sleep disorders still persist.
The study has also revealed that the time of the day that chemotherapy drugs
are administered to cancer patients will actually determine their efficacy and
effectiveness as also the extent of side effects.
Every living creature including human beings have a hidden mechanism
called the body's circadian or biological clock that takes care of various vital
functions, both physiological and biological. So far scientists believed that
any disruption of this mechanism will have bad impact on one's health. But
the present study negates the existing belief and establishes that a change in
the circadian clock will help at least in preventing the growth of cancer cells.
"The results have important implications for cancer treatment. Our body's
daily rhythms are synchronised with the sun and coordinated by the body's
circadian clock. While a region of the brain operates as the master biological
clock, the system is complex and operates in virtually every cell of the body.
It regulates our sleep, body temperature, eating habits and activity level,"
says Dr Shobhan.
The team found that the extracts obtained from mouse brains in the morning
repaired damaged DNA samples six to seven times faster than those taken at
night. To find out the exact mechanism behind it, the scientists analysed the
levels of six core excision repair proteins over a 24-hour period.
Levels of one DNA damage repair protein called xeroderma pigmentosa A
(XPA) proved to be much higher in the mouse brains during the day than at
night. To confirm that reduced excision repair at night was affected by low
levels of XPA, the scientists added known amounts of XPA to the extracts.
"Adding extra XPA to the samples taken at night increased their ability to
repair damaged DNA samples. In contrast, for samples collected in the
morning, the extra XPA had little effect on the ability to repair damaged
DNA. These results support the idea that DNA repair depends at least in part
on fluctuating levels of XPA," Dr Shobhan said adding that by hitting cancer
cells with chemotherapy at a time when their ability to repair themselves is
minimal, one can maximise effectiveness and minimise side effects of
The new study found that genetically altering one of four essential biological
clock genes actually suppressed cancer growth in a mouse model. Further
research will help doctors to reset the internal clock of each cancer cell to
render it more vulnerable to attack with chemotherapeutic drugs.
"Adjusting the clock in this way could certainly be a new target for cancer
treatment. Our study indicates that interfering with the function of these
clock genes in cancer tissue may be an effective way to kill cancer cells and
could be a way to improve upon traditional chemotherapy," said team head
Dr Aziz Sancar.
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