Scientists have identified a new protein involved in the development of drug resistance in breast cancer

Researchers from Imperial College London have found that blocking a protein called LMTK3 in human cancer cells that were resistant to tamoxifen made the cells more responsive to the drug. In a mouse model of the disease, using genetic techniques to block the production of LMTK3 led to a significant decrease in the size of breast tumours.

The researchers also measured levels of LMTK3 in tissue samples taken from women with breast cancer. They found that women who had higher levels of LMTK3 in their tumours tended to live less long and were less likely to respond to hormone therapy. In addition, they found that particular mutations in the gene coding for LMTK3 also correlated with how long a patient would survive.

"Anti-oestrogen drugs have been very successful at allowing women with breast cancer to live longer, but resistance to these drugs is a common problem," said Professor Justin Stebbing, from the Department of Surgery and Cancer at Imperial College London, the study's senior author. "Our results suggest that the action of LMTK3 on the oestrogen receptor has a crucial role in the development of drug resistance.

"We're now looking for drugs that can block the effect of LMTK3, which we could hopefully give to patients to prevent them from becoming resistant to hormone therapy. It will probably take at least five to ten years to develop new treatments that are safe to be used in humans."

Breast cancer is the most common cancer in the UK, affecting about 46,000 women each year. More than two thirds of breast tumours contain oestrogen receptors, meaning that they require the hormone oestrogen to grow and they can be treated with anti-oestrogen drugs such as tamoxifen. However, many patients develop resistance to these treatments so that the drugs eventually cease to be effective.

Abnormal, uncontrolled cell division resulting in a malignant tumour that may invade surrounding tissues or spread to distant parts of the body. Full medical glossary
The basic unit of all living organisms. Full medical glossary
The basic unit of genetic material carried on chromosomes. Full medical glossary
Relating to the genes, the basic units of genetic material. Full medical glossary
A substance produced by a gland in one part of the body and carried by the blood to the organs or tissues where it has an effect. Full medical glossary
A change in the genetic material (DNA) of a cell, or the change this this causes in a characteristic of the individual, which is not caused by normal genetic processes. Full medical glossary
A hormone involved in female sexual development, produced by the ovaries. Full medical glossary
Compounds that form the structure of muscles and other tissues in the body, as well as comprising enzymes and hormones. Full medical glossary
The ability of a microbe, such as a type of bacteria, to resist the effects of antibiotics or other drugs. Full medical glossary
A microbe, such as a type of bacteria, that is able to resist the effects of antibiotics or other drugs. Full medical glossary
A group of cells with a similar structure and a specialised function. Full medical glossary
An abnormal swelling. Full medical glossary