Breast cancer gene breakthrough

The BCRA1 molecule: Linked to breast cancer

Scientists have taken a major step towards understanding the gene that causes breast cancer.

Researchers from the Imperial Cancer Research Fund are the first to build a three dimensional model of an important region of a protein molecule found in the BRCA1 gene - linked to breast cancer.

The research should enable scientists to explain why some genetic changes can cause the molecule to alter its shape and so prevent it from doing its job of suppressing tumours.

Genes hold the recipes for proteins and the proteins then carry out the work of the gene in controlling the life of the cell.

Mutations in a gene can upset a cell by changing the amount or the activities of the protein.

A gene that normally suppresses tumour growth may be inactivated by a mutation, thus depriving the cell of the crucial brakes needed to stop the controlled division typically found in cancer.

Dr Paul Freemont, who led the research team, said: "This is a very important piece of research. We have worked out the three dimensional structure of part of a protein which is found in about 50 other gene products, including BRCA1.

"We can now look at BRCA1 mutations in much greater detail than was possible before and see how they affect the shape of the molecule.

"BRCA1 was discovered about five years ago and despite a great deal of research world wide we still do not know exactly what it does or how it works or how altering its function affects a woman's pre-disposition to breast or ovarian cancer."

Hereditary link

According to the Imperial Cancer Research Fund, breast cancer affects one woman in 12 in the UK, and about 5% of cases are due to hereditary factors.

Mutations in the BRCA1 gene are thought to be responsible for about 45% of these inherited breast cancers.

In addition, those who carry the faulty BRCA1 are four times more likely to develop bowel cancer, and male carriers are three times more at risk of prostate cancer.

Dr Freemont said: "There are many unclassified mutations in the BRCA1 gene where we don't know if they cause cancer or not.

"One important aspect of our work is that we can now begin to assess what they do and how they might affect this bit of the BRCA1 molecule."