Researchers have developed a novel method to study the mechanism by which estrogen/progesterone hormone receptors interact with DNA to regulate breast tumor growth. The paper entitled “Progesterone receptor modulates ERα action in breast cancer“ was published in the journal Nature.

Breast cancer is characterized by the uncontrolled growth of breast cells eventually forming malignant tumors. Though its causes are still not fully understood, various risk factors have been pointed out that contribute toward tumor growth including cigarette smoking, genetics, and birth control therapy.

Mechanistically, abnormal levels of female sex hormones have been linked to breast cancer. There are two types of hormone receptors, estrogen receptors (ER+) and progesterone receptors (PR+), with most breast cancers identified as ER+. However, the role of estrogen/progesterone hormones and their receptors in breast cancer progression are not sufficiently understood to aid the development of efficient therapies. In this study, researchers developed a new method, using state-of-the-art DNA reading technology, to visualize areas where estrogen receptors are attached to DNA and activate specific genes. These visualized maps were compared with breast cancer cells grown with and without influence from progesterone. “Traditionally, breast cancer tumours are destroyed once they have been removed from a patient. The new technique we have developed sees tumour cells from participating patients ‘rescued’ for research purposes,” study author and Professor Wayne Tilley, University of Adelaide’s Dame Roma Mitchell Cancer Research, said in a press release.

The results displayed how activated progesterone receptors were capable of reorienting the estrogen receptor to other DNA areas, where alternative genes were activated to decelerate tumor 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 oestrogen receptor, which could improve treatment for the majority of hormone-driven breast cancers,” Professor Tilley added.

Overall, this new method provides new insights into the role of progesterone in breast cancer and how hormones regulate tumor growth. In the future, this method could be useful to provide individualized treatment for patients with breast cancer, allowing researchers to visualize the interaction and response of the tumor with the therapeutic agent.