Breast cancer: prolactin vs. ketosteroids

"The data we have collected shows that the hormones used in the treatment of breast cancer and which our body produces in response to stress can greatly influence how the disease develops and what awaits the patient in the end. Of course, these results need additional confirmation during clinical trials before we can decide what we should do," said Hallgeir Rui from Thomas Jefferson University in Philadelphia (an abridged retelling of the university press release, Stress hormones could undermine breast cancer therapy, can be read on the Medical website News Today – VM).

Rui and his colleagues uncovered the unexpected role of hormones in the development of breast cancer and in the acquisition of resistance to chemotherapy by studying the medical histories of women whose tumors could not be contained and treated with drugs that block the work of estrogen, the "female" hormone whose molecules stimulate the growth of breast cancer.

Studying the work of cells in their tumors, scientists noticed that this invulnerability is a product of the vital activity of the so-called CK5 cells (cytokeratin-5-positive cells), whose growth is stimulated by another sex hormone – progesterone, which a woman's body produces during pregnancy.

The vast majority of women suffering from aggressive forms of breast cancer have long passed the reproductive age, which is why scientists initially did not pay attention to this fact. But after a while, Rui and his colleagues noticed that progesterone is similar in structure to a number of completely different hormones from steroids that are produced during stressful situations. The same hormones are used by doctors during chemotherapy to treat the condition of patients.

This forced the doctors to return to experiments with samples of cancer cultures and check how they would react to molecules of similar substances. This experiment led to very unexpected and revealing results – two of the four hormones caused rapid growth of CK5 cells, increasing their number by 4-7 times and making the tumor invulnerable to chemotherapy.

This reaction, as further experiments have shown, can be suppressed with the help of another hormone – prolactin, which is released by the body of a woman when breastfeeding a baby. When its molecules appear, CK5 cells stop multiplying, which makes it possible to destroy them with the help of chemotherapy.

As Rui and his colleagues warn, women with breast cancer should not run to the pharmacy for prolactin yet – this substance is not completely harmless and it is also involved in the development of some other forms of breast cancer. The safest option, according to Rui, is to find alternatives for stress hormones to suppress the negative effects of chemotherapy.

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24.06.2015