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Stem Cells in Breast Cancer

What causes breast cancer?

Both genetic and non-genetic factors -- including age, radiation exposure, menstrual history and number of pregnancies -- are involved in the development of breast cancer.

For example, we know that women who inherit mutations in certain genes, especially BRCA1 and BRCA2, have a much higher risk of developing breast cancer. Mutations in HER2 and PTEN - genes involved in DNA repair and tumor suppression - are often present in aggressive breast cancers.

It is likely that some or all of these factors are involved in the development of breast cancer. But regardless of the triggering factor, U-M scientists believe that all types of breast cancer originate in stem cells, or cells called progenitors, which come from these stem cells in the breast.

What have U-M scientists learned about breast cancer stem cells?

Scientists at the U-M Cancer Center have been intensively studying breast cancer stem cells since their discovery in 2003. The more we know about these cells, the more likely we are to find ways to block their ability to drive the development of breast cancer. Every research advance provides an important clue that could lead to new treatments for the disease.

Recent discoveries by Cancer Center scientists include:

• Mutations in genes called HER2 and PTEN triggered rapid cell division and self-renewal in breast cancer stem cells. This caused the stem cells to develop abnormally and invade surrounding breast tissue. When the scientists treated the cells with drugs known to inhibit activity of these genes, the number of cancer stem cells dropped dramatically.
• In a study with mice, U-M scientists identified a receptor molecule on the surface of breast cancer stem cells and found that it triggered abnormal cell growth in response to tissue inflammation and damage caused by chemotherapy. When this receptor was blocked, the breast cancer stem cells died, preventing the cancer from spreading.
• U-M scientists discovered that progenitor cells in bone marrow called mesenchymal stem cells are involved in the development of breast cancer. The researchers found that breast tumors in mice sent out signals that caused mesenchymal stem cells to move from bone to the tumor. Once in the tumor, they stimulated cancer stem cells to divide and spread.
• A dietary component called sulforaphane, found in broccoli, killed breast cancer stem cells and prevented new tumors from growing in laboratory mice. Its ability to target cancer stem cells could explain sulforaphane's effectiveness in breast cancer prevention.
• U-M scientists found that curcumin, a component derived from the Indian spice turmeric, and piperine, derived from black peppers, decreased the number of stem cells in breast cells grown in a laboratory dish. The components had no effect on normal differentiated cells.

Do breast cancer stem cells cause metastasis?

There are many factors that trigger metastasis in cancer and scientists don't yet understand how they all work. But we do know that stem cells are involved in the process. Recent research by U-M Cancer Center scientists found that cells from tumors with a higher percentage of cancer stem cells were more likely to break away and spread.

Updated 3/2011

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Learn more:
In 2003, U-M Cancer Center scientists discovered the fingerprint for breast cancer stem cells. Read the press release.

Stem cell research at the University of Michigan
Stem Cells - Explained and Explored

Other stem cell resources
National Institutes of Health Web site on stem cells

International Society for Stem Cell Research

Broccoli Versus Breast Cancer Stem Cells
a video blog from NutritionFacts.org