Receptors that mediate activity of the female sex hormones (estrogen and progesterone) interact with DNA to control the growth of a large majority of breast cancers. These findings were published in Nature (2015; doi:10.1038/nature14583).

The study used a technique that “rescues” breast cancer cells for research, which was developed by researchers at the University of Adelaide’s Dame Roma Mitchell Cancer Research Laboratories in Australia and led by Wayne Tilley, PhD. Coupled with advanced scientific technologies pioneered by Cambridge University in London, Great Britain, this has provided a unique insight into the hormone regulation of breast cancers, which is expected to lead to new treatments for the disease.

“Traditionally, breast cancer tumors are destroyed once they have been removed from a patient,” said Tilley. “The new technique we have developed sees tumor cells from participating patients ‘rescued’ for research purposes.

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“This technique, which is used to test current and new forms of therapy on tumor cells, has potential to one day provide an individualized treatment option for the patient based on how the tumor responds to therapy.

“The method is also a vital research tool. It has helped shed light on the mystery of progesterone action that has confounded researchers and clinicians for a long time,” Tilley said.

Jason Carroll, PhD, from the University of Cambridge’s Cancer Research UK Cambridge Institute, said they have discovered why patients with a particular type of hormone-driven breast cancer tend to have a better chance of recovery.

“We used state-of-the-art DNA reading technology to create maps showing where the estrogen receptor attaches to DNA to switch on genes,” said Carroll. “We then compared these maps in breast cancer cells grown with and without progesterone. This revealed how the ‘switched on’ progesterone receptor redirects the estrogen receptor to different DNA regions – switching on a different set of genes that slow down cell growth.

“This important research helps explain why some breast cancer patients have a better prognosis. Crucially, it has provided a strong case for a clinical trial to investigate the potential benefit of adding progesterone to drugs that target the estrogen receptor, which could improve treatment for the majority of hormone-driven breast cancers,” he said.