EPFL makes an important discovery about breast cancer


A French-speaking team has managed to better understand the role of two hormones in the development of tumors, with prospects for treatment.

The interaction between estrogen and progesterone receptors and their effect on breast cancer were little known until now. Pretext image.

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Estrogen and progesterone are female hormones. Estrogen (ER) and progesterone (PR) receptors are found on or in normal breast cells and some types of breast cancer cells. It is at these receptors that hormones bind to cells. Once attached, the hormones can affect the cells’ behavior or growth, explains the Canadian Cancer Society.

Breast cancer affects one in seven women and is the most commonly diagnosed cancer worldwide. More than 70% of all breast cancers are classified as estrogen positive based on detection of the estrogen receptor in at least 1% of tumor cells. Blocking this receptor is the classic goal of hormonal treatments, which have significantly improved patient survival rates.

lack of models

The problem is that tumors that are estrogen receptor positive have been understudied because the field lacks adequate models. When we tried to grow breast cancers in genetically modified mice, “they were not responsive to hormones, and the success rates of estrogen receptor-positive breast cancer xenografts are extremely low,” says Professor Cathrin Brisken of the School of Science. of Life of the EPFL.

Previous studies have revealed an important interaction between the estrogen receptor and the progesterone receptor. However, the lack of suitable cell lines and animal models has prevented scientists from adequately studying this interaction. Since the progesterone receptor gene is affected by the estrogen receptor, hormone treatments targeting the latter can block the expression of the former. This complexity makes it difficult to study the role of each receptor independently and, therefore, to optimize treatment strategies.

Successful mouse transplant

Today, in collaboration with a medical and research team from the CHUV, the Réseau Lausannois du Sein and the ICPI (International Institute for Cancer Prevention), Cathrin Brisken’s laboratory has successfully transplanted positive human breast cancer cells to the recipient of estrogen in the milk ducts of immunocompromised women. mice. This breakthrough allowed them to study the effect of estrogen and progesterone on the development of breast cancer.

Scientists have discovered that these two hormones, estrogen and progesterone, can increase tumor growth and that combined treatments can promote metastasis and thus the spread of cancer.

The progesterone receptor may be a target

But there is a way to deal with that. “We found that tumors react differently to the two hormones in different patients, which suggests that it is possible to improve treatment by adapting it,” explains Cathrin Brisken. “In addition, suppression of progesterone receptor expression may be a therapeutic option,” she adds. “While it was claimed that progesterone could help women with breast cancer, we show that this hormone promotes tumors and that the progesterone receptor mediates estrogen receptor signaling, making this receptor interesting as a target. potential therapeutic.

The study, which was published in the journalNatureCommunicationsIt was also presented by the Director of the Society of Endocrinology at the ENDO 2022 event that brought together more than 7,000 doctors and scientists and took place from June 11 to 14 in Atlanta, United States.

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