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Last Updated: Sunday, 16 March 2008, 00:02 GMT
Tumour growth block hopes raised
Breast cancer cells dividing
Cancer cells divide in uncontrolled and rapid fashion
Scientists have discovered a key part of the chemistry which makes cancer cells so dangerous.

They believe it could now be possible to tamper with the mechanism - and stop tumour growth in its tracks.

Harvard Medical School identified an enzyme which enables cancer cells to consume the huge quantities of glucose they need to fuel uncontrolled growth.

Writing in Nature, they describe how starving cancer cells of the enzyme curbed their growth.

We don't yet know whether these findings can be applied to human cancers outside the lab
Dr Joanna Peak
Cancer Research UK

The key enzyme, pyruvate kinase, comes in two forms, but the Harvard team found that only one - the PKM2 form - enables cancer cells to consume glucose at an accelerated rate.

When the researchers forced cancer cells to switch to the other form of pyruvate kinase in the lab by knocking out production of PKM2, the cells' growth was curbed.

When the cells were injected into mice, they were much less able to produce tumours.

Warburg effect

The fact that proliferating cancer cells are able to consume glucose at a much higher rate than normal cells was first discovered by the German Nobel prize-winning chemist Otto Warburg more than 75 years ago.

He also showed that the amount of glucose the cells needed to keep their vital signs ticking over was minimal, allowing them to grow and divide at the prodigious rate usually associated with foetal cells.

Warburg's discoveries are still used today to detect spreading cancers.

However, until now the chemistry behind the "Warburg Effect" has not been well understood.

The researchers said the exact chemistry behind glucose metabolism probably varied between types of cancer.

However, lead researcher Professor Lewis Cantley said: "Because PKM2 is found in all of the cancer cells that we have examined, because it is not found in most normal adult tissues, and because it is critical for tumour formation, this form of pyruvate kinase is a possible target for cancer therapy."

Dr Joanna Peak, of the charity Cancer Research UK, said: "We don't yet know whether these findings can be applied to human cancers outside the lab, so more research is needed before we can consider developing cancer treatments that target this process."

However, Dr Peak said a drug called DCA which is thought to act on the relevant pathway was currently undergoing tests.



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