According to a US study, stress hormones may have a negative impact on breast cancer. The results published in "Oncogene", show that several hormones, which are also produced by the body and used to treat side effects of cancer therapy, stimulate the growth of therapy-resistant tumour cells.
Women with ER positive breast cancer (oestrogen receptor positive) normally show a good response to therapies with aromatase inhibitors or hormone blockers. But a quarter of the patients develop resistance against the medications. These resistances are partially caused by a subset of cancer cells, called CK5 cells. Previous studies had already shown that progesterone can stimulate the growth of these cells. But since most ER-positive breast carcinomas develop after menopause when progesterone production has stopped, this was, to date, not a major concern.
Researchers at the Thomas Jefferson University in Philadelphia (Pennsylvania) now tested whether other hormones in this group of 3-ketosteroids, which are frequently produced by the body in times of stress, such as glucocorticoids, may influence this process. They exposed breast cancer cell lines to four different 3-ketosteroids and determined that dexamethasone and aldosterone led to a four- to seven-fold increase in the number of CK5 cells. The results were also confirmed in human breast cancer grown in mice, showing increased therapy resistance in animals treated with these hormones.
"Not only are these steroids sometimes used in cancer treatment, glucocorticoid hormones are also naturally produced by the body in response to stress", explained lead author Chelain Goodman. By adding prolactin, the expansion of CK5 cells was prevented. However, the hormone can also drive other types of breast cancer, thus it was advised to proceed with caution. Alternative possibilities included a protein which is important for steroid induction of CK5 cells, or finding an alternative to steroids to treat side effects of chemotherapy, said Goodman.
Univadis
