Body fat protein adiponectin plays role in tumour growth

Scientists have discovered how low levels of a protein hormone found in body fat, plays a crucial role in tumour growth and spread. Their findings are published in a paper in the British Journal of Cancer.

Postmenopausal women who are overweight are at greater risk of developing breast cancer, as large amounts of body fat secrete much higher levels of the hormone oestrogen and the growth factor leptin, which can encourage tumours to grow. New research in mice and breast cancer cell lines, from scientists at the Hormel Institute, University of Minnesota, shows how low levels of a protein hormone called adiponectin or Acrp30 may help to trigger the disease.

The study, the first to examine and clarify the role played by two different forms of Acrp30, full length (Acrp30) and globular (gAcrp30), in tumour growth, is further evidence of an obesity link to breast cancer.

Previous research into adiponectin, which is only found in body fat, has shown that levels increase when individuals lose weight, either through dieting or as the result of gastric bypass surgery. Reduced levels of Acrp30 have also been linked with other diseases influenced by diet such as type 2 diabetes and coronary artery disease.

Lead researcher, Professor Margot Cleary, said "In the developed world, as the average body mass index climbs, it's vital that we understand the interaction of adiponectin with other growth factors such as leptin in breast cancer spread.

"Our findings indicate that adiponectin, which is released from fat tissue may protect against oestrogen receptor positive tumour development when levels are high, it's also likely that a balance between leptin and Acrp30 determines whether a tumour increases or decreases in size."

Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "We've known for some time that the overproduction of oestrogen in women who are overweight can play a part in the development of different types of breast cancer. This study which examines how obesity linked proteins interact, adds to the compelling evidence that maintaining a healthy body weight can help prevent disease."

Margot Cleary, Ph.D., is professor of nutrition and metabolism at the University of Minnesota's Hormel Institute and member of the University's Cancer Center.

The University of Minnesota Cancer Center is a Comprehensive Cancer Center designated by the National Cancer Institute in Washington, D.C. Advancing knowledge about cancer and enhancing care for patients is the mission of the Cancer Center. Its faculty and staff foster that mission by conducting basic, clinical, and population research; providing treatment to patients; and presenting educational programs.