Dec. 22, 1997 CSIRO livestock researchers are exploring extracts of cattle cartilage as a possible potent new weapon in the war on cancer, the Chief of CSIRO Tropical Agriculture, Dr Elizabeth Heij, has announced.
A team led by Dr Greg Harper of CSIRO's J.M.Rendel Laboratory in Rockhampton is working to identify special factors in cattle cartilage shown by international research to prevent a cancer from developing a blood supply and spreading round the body.
In the process they hope to add a valuable new product to Australia's $4 billion cattle and meat industry.
"Overseas scientists have demonstrated that certain extracts of shark cartilage, injected into tumours, cause them to regress. They also appear to inhibit the development of blood vessels to the cancer, which allows them to spread round the body," Dr Harper explains.
"The shark cartilage extract market is already worth $1 billion a year in the US alone æ but, worldwide, sharks are in short supply. Our marine scientists believe that shark fishing cannot support the predicted growth in demand for this product."
However Dr Harper's work has established that similar factors occur in bovine cartilage æ and Australia produces thousands of tonnes of this from the 7 million cattle the beef industry processes each year.
"To reach the body's blood supply and spread, a cancer first has to pass through a matrix of extra-cellular material," he says.
"Cartilage is a tissue that functions without nerves, blood vessels or a lymphatic system and consists largely of extra-cellular material æ and it is these characteristics which make it useful in trying to stop a cancer from spreading.
"Also it contains factors which interfere with the cancer's passage. We believe that by increasing these factors, the cancer is forced to expend more energy in trying to get through the extra-cellular matrix, making it far more difficult for it to spread, or metastatise."
The factors go by the family name of glycosaminoglycans æ or GAGs for short. Dr Harper and researcher Xiaoyi Qui from Beijing's Tiantan Hospital in China, are hard at work trying to identify and characterise the particular GAGs in bovine cartilage that do the best job of inhibiting cancer spread.
"The reason we believe cattle are such an important source is that, so far, nobody has succeeded in synthesising these compounds. That means the supply will continue to rely on natural sources.
"Shark fishing is probably an unsustainable way of obtaining them, but we believe that domestic cattle offer a very promising alternative," he says.
The goal of the research is to make GAGs a valuable coproduct of the beef industry. Overseas, shark cartilage extract sells for $250-500 a kilo, but here bovine cartilage mainly goes into blood-and-bone fertiliser.
"About one per cent of every cattle carcase consists of cartilage, and nearly a third of that consists of GAGs æ so the value-adding potential for the meat industry is considerable," Dr Harper says.
"The real challenge is to identify which of the GAGs are most active against cancers."
Down the track, he envisages bovine GAGs not just as a medical treatment, but potentially an additive for therapeutic foods æ just as some special foods are now enriched with substances which protect the consumer against heart disease, osteoporosis and cancer.
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