Researchers Discover New Breast Cancer Culprit

Protein shown to speed and intensify spread of breast cancer to other organs

(RxWiki News) When scientists identify concentrations of regulatory T cells (immune-system cells) in breast cancer tumors, it usually signifies an unfavorable prognosis. Now researchers have uncovered why.

Researchers at the University of California, San Diego School of Medicine found that these regulatory T cells produce a protein called RANKL (an inflammatory protein normally involved in bone remodeling) that speeds and intensifies the spread of breast cancer to distant organs, increasing mortality risk in the process.

The discovery of RANKL may lead to better drug treatments since interfering with the ability of the RANKL protein to interact with cancer cells appeared to block tumor progression.

When synthetic RANKL was injected directly into tumors, an increase in metastasis (cancer spreading) was seen, suggesting the protein may be key to regulatory T cells' ability to promote the spread of breast cancer.

RANKL has been implicated in a variety of degenerative diseases, including rheumatoid arthritis and bone metastasis.

Previous research linked RANKL to the development of progestin-driven breast tumors, the presence of which is increased by hormone replacement therapy and contraceptives that contain the hormone progestin.

Except for non-melanoma skin cancer, breast cancer is the most prevalent cancer among women in the United States, affecting as many as one in eight American women.

Review Date: 
February 17, 2011