Two molecules isolated from an extract
of crushed pineapple stems have shown promise in fighting
cancer growth.
One molecule called CCS blocks a protein called Ras,
which is defective in approximately 30% of all cancers.
The other, called CCZ, stimulates the body's own immune
system to target and kill cancer cells.
It is hoped the research, carried out by Queensland
Institute of Medical Research, could lead to new anti-cancer
drugs.
The extract studied by the scientists, bromelain, is
a rich source of enzymes and is widely used as a meat
tenderiser, to clarify beer and tan leather hides.
The Queensland team discovered that the extract also
had pharmacological properties and could activate specific
immune cells while, simultaneously, blocking the immune
function of other cells.
Lead researcher Dr Tracey Mynott said: "We suspected
that different components of the crude mixture might be
responsible for bromelain's biological effects.
"In searching for these components, we discovered the
CCS and CCZ proteins and found that they could block growth
of a broad range of tumour cells, including breast, lung,
colon, ovarian and melanoma."
New action
Both CCS and CCZ are protease enzymes, more usually
associated with breaking down proteins, as in the digestive
process.
Dr Mynott said it was the first time this class of enzymes
had been shown to have a specific effect on the immune
system.
"The way CCS and CCZ work is different to any other
drug in clinical use today.
"Therefore, CCS and CCZ will represent a totally new
way of treating disease and potentially a whole new class
of anti-cancer agent."
Dr Julie Sharp, at Cancer Research UK, said: "The origin
of many anti-cancer drugs can be found in nature.
"However, it's early days for this research
and the real test will be to see if the effects seen in
the lab can be reproduced successfully in patients."
