Cholesterol breakdown product is said to promote the development of breast cancer tumors
A cholesterol breakdown product could increase the risk of breast cancer and metastases. American researchers found this out in animal experiments. The substance 27-hydroxy-cholesterol (27HC) mimics the hormone estrogen and drives the growth of breast cancer tumors. The results should also be transferable to humans.
High cholesterol has an adverse effect on breast cancer healing prognosis. The connection between obesity and breast cancer has been known for some time. So far, however, which mechanism is responsible for the fact that overweight people have an increased risk of tumors in the breast has been an unsolved mystery. US researchers led by Donald McDonnell from Duke University Medical School in Durham, North Carolina, may have found an explanation. As the scientists report in Science magazine, cholesterol breakdown product 27HC is responsible for the fact that elevated cholesterol levels increase the risk of breast cancer and the formation of metastases, and worsen the chances of recovery.
"Many studies show a link between obesity and breast cancer and, in particular, that increased cholesterol is linked to the risk of breast cancer, but so far no mechanism has been discovered," McDonnell is quoted in a statement from his institute. "We have now found a molecule - not cholesterol itself , but a common breakdown product called 27HC - that mimics the hormone estrogen and drives breast cancer growth. " Around a quarter of breast cancer tumors have an increased sensitivity to the sex hormone.
Enzyme makes breast cancer more aggressive As has been shown in mice with breast cancer, 27HC not only favors the development of breast tumors, they also metastasize more. Anti-estrogens, on the other hand, have an inhibitory effect on the cholesterol breakdown product.
The results of the researchers were confirmed in studies on human breast cancer cells. Another substance was discovered that also made the tumors more aggressive: the enzyme CYP27A1 breaks down cholesterol to 27HC and activates the cancer cells. Therefore, estrogen inhibitors may fail in some cases of hormone-sensitive breast cancer.
“In human breast cancer samples, the CYP27A1 level correlated with the degree of tumor. In higher-grade tumors, both tumor cells and the macrophages associated with the tumor showed a high level of the enzyme, ”the researchers write in the magazine.
"This is a very important finding," McDonnell continues to quote in the institute's announcement. "Because human breast tumors form this enzyme for the production of 27HC, they produce an estrogen-like molecule that can promote tumor growth. This is how the tumors have a mechanism with which they can use another fuel source. "
Lowering Cholesterol Levels to Prevent Breast Cancer The researchers' conclusion: Cholesterol-conscious diet or drug control of cholesterol levels is very likely to reduce the risk of breast cancer. In addition, such measures could have the consequence that the effectiveness of cancer therapies with aromatase inhibitors or tamoxifen improves if the disease already exists.
"So far, it was known that there is a connection between high cholesterol and breast cancer risk," Professor Klaus Parhofer from the University of Munich Großhadern clinic told the news agency "dpa". "However, the connection was not understood. This study confirms the causality and also shows the mechanisms. " According to the endocrinologist, the researchers' results are transferable to humans. How large the effect is, however, needs to be clarified in further studies.
Breast cancer is the most common type of cancer in women. About every eighth woman suffers from it today. As scary as the diagnosis is for the patients, it is no longer synonymous with a death sentence thanks to great advances in diagnostics and therapy. According to the German Society for Senology (DGS), around 80 percent of women who are ill can be successfully treated today. Basically, the earlier a tumor is discovered, the greater the chances of recovery. (ag)
Image: KFM / pixelio.de