Scientists looked at the energy mechanism in cells

Experts from Cancer Research UK in Glasgow studied cell mitochondria which generate energy and growth in cells.

They found that a build-up of a metabolic molecule in them could start a sequence leading to tumour growth.

A leading cancer scientist said the study would prove helpful in understanding cancer and ways of tackling it.

Researchers based at the University of Glasgow's Beatson Institute for Cancer Research have published their findings in the latest edition of Cancer Cell.

Scientists said that some genes which code for the energy producing mechanism in mitochondria act to suppress tumours.

However, defects in these genes within the complex structures can result in cancer.

Mutations in SDH can predispose a person to cancer of the kidney, adrenal gland and thyroid gland Dr Lesley Walker Cancer Research UK

The experts focused on a tumour suppressor gene called SDH, which codes for the molecule called succinate dehydrogenase.

Damage to the SDH gene results in an accumulation of a product called succinic acid in cells which in turn leads to a rise in levels of a protein called HIF-1.

The scientists said HIF-1 is normally only activated as a result of "certain types of crisis" in cells, such as a lack of oxygen, and in those circumstances would encourage blood vessel growth in order to help cells to oxygenate.

Researchers found what they said were "missing pieces in this puzzle".

High levels of succinic acid in cells, which result from SDH mutations, block cells' normal process of getting rid of HIF-1.

A build-up of HIF-1 levels can lead to inappropriate blood vessel growth, which "feeds" the tumour.

'Tumour development'

Dr Eyal Gottlieb, of the University of Glasgow's Beatson Institute, said: "We found that damage to the SDH gene boosts the levels of succinic acid in a cell and this, in turn, prevents the degradation of HIF-1.

"HIF-1 is then free to increase the expression of genes that facilitate blood vessel growth, tumour development and cancer spread."

Dr Lesley Walker, the Director of Cancer Information at Cancer Research UK, said: "Mutations in SDH can predispose a person to cancer of the kidney, adrenal gland and thyroid gland. Changes in SDH activity may also be associated with stomach and bowel cancer.

"This study is exciting because it is the first to find a molecular mechanism that links mitochondrial mutations to tumour formation.

"Increasing our understanding of the molecular basis of cancer is crucial if we are to find new ways of preventing, diagnosing and treating the disease in the future."