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BBC NEWS - BBC ONLINE NETWORK
Monday, April 12, 1999 Published at 18:05
GMT 19:05 UK
Health: Tapioca treatment for cancer
For many adults, tapioca is inextricably
linked to school dinners
Tapioca
pudding - widely known as frog's eggs by
many school pupils - may after all be good
for you.
Scientists say the plant from which it is
derived may help cure cancer.
Tapioca is
derived from the cassava plant.
It is one
of many plants which manufactures cyanide to
deter animals who might want to eat it.
It does
this by producing a chemical called
linamarin which releases hydrogen cyanide
when it is broken down by the linamarase
enzyme.
Geneticists
at Newcastle University have been taking
genetic material from the cassava plant and
adding it to a virus.
This is
then introduced into cancer cells which have
been impregnated with linamarin from the
cassava plant.
The aim is
for the cancer cells to produce hydrogen
cyanide in high enough doses so that they
commit suicide.
Hydrogen
cyanide
Professor
Monica Hughes has been studying cassava and
cancer for seven years.
She has
cloned the genes from the plant which are
responsible for producing hydrogen cyanide.
Her
objective is to reduce the toxicity of the
cyanide so that it will not harm humans.
Cassava is
a staple crop for many people in Africa,
Asia and South America, but, if it is
processing wrongly, it can lead to cyanide
poisoning.
Because the
plant is rarely used in Western diets, it
has not been subject to much scrutiny by
geneticists.
Professor
Hughes has been working with a research team
in Madrid to modify the cassava gene and
transfer it to a retrovirus.
This gives
the retrovirus the ability to produce
linamarase.
The Spanish
researchers found that a brain tumour in a
rat was totally eradicated after one week of
the genetic treatment.
It allowed
the localised release of small doses of
cyanide through the breakdown of linamarin
by linamarase.
Neighbouring cells
The team
found that part of the reason the tumour was
so quickly destroyed was that the cells
containing the retrovirus also affected
surrounding cells.
They say
tests on human tissue samples for certain
cancers also look promising.
Professor
Hughes' research has been funded by the
European Union, but her funding has now run
out and she is looking for other sources.
She says
her next step is "to modify the genetic
material with a view to making the treatment
more effective when applied to mammalian
cells".
A spokesman
for Newcastle University said the research
showed how genetically modifying plants
could bring beneficial effects.
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