Progestin May Create Stem-Like Breast Cancer Cells

Discovery may lead to new immunotherapies for aggressive breast cancer.

Novel findings suggest that natural and synthetic progestin may play a role in the creation of breast cancer cells that act similarly to stem cells, according to a study published by Breast Cancer—Targets and Therapy.

These results may help scientists target a group of rare breast cancer cells that are known to metastasize. The findings could also help discover novel immunotherapies to attack these cells, according to the study.

Hormone replacement therapies are typically prescribed to reduce the symptoms of menopause in women. These treatments contain female hormones to replace hormones not produced by the body.

Previous studies show that hormone replacement therapy may increase the risk of breast cancer, the authors noted.

“In previous studies, we have shown that both natural and synthetic progestins accelerate the development of breast cancer and increase their metastasis to lymph nodes,” said Salman Hyder, PhD. “Our laboratory is committed to identifying the cell mechanisms that bring about increased breast cancer risks. Recently, our research focused on special cells—which are called ‘cancer stem cell-like cells’—that induce aggressive tumor growth, metastasis, and cancer recurrence.”

In the current study, the authors used hormone-responsive breast cancer cells to determine the impact of progestin on cell markers found in the disease.

They discovered that both natural and synthetic progestin increased expression of the CD44 protein. This protein is involved with cell proliferation, cell communication, and migration, which are all characteristics of aggressive cancer, according to the study.

The authors found that progestin causes cells to behave similarly to stem-like cancer cells. These cells act like normal stem cells, as they are self-renewing, self-replicating, and proliferate exponentially, according to the study.

Additional testing revealed that the subset of cancer cells was driven by the presence of progestin.

“The findings show that exposure to natural and synthetic progestins leads to the development of these cancer stem-cell like cells,” Dr Hyder said.

Although further studies are needed, these findings could have important implications for women. Not only are progestins included in hormone replacement therapy, they are also fairly common in oral contraceptives.

These findings suggest that women taking synthetic progestin may be at an increased risk of aggressive breast cancer.

“These cells greatly increase the likelihood of resistance to therapies and the risk for metastasis,” Dr Hyder concluded. “Our findings also suggest that clinicians may be able to combat the progestin-dependent tumor growth through immunotherapy.”