Cancer Stem Cell Research
Cancer stem cells are the small number of cells within a tumor that drive the tumor's growth. These cells generally make up just 1% to 3% of all cells in a tumor
At the U-M Comprehensive Cancer Center, we believe treatments designed to target and destroy cancer stem cells will revolutionize how we treat cancer. Over the last 30 years, researchers have developed more effective treatments for cancers like childhood leukemia, Hodgkin's disease and testicular cancer.
Death rates for some common cancers, like breast and prostate cancer, have gone down due to advances in early detection and prevention. However, the survival rate for patients with many advanced cancers has not changed significantly for decades, and cancer is still the second-most common cause of death in the United States.
Instead of trying to kill all the cells in a tumor with chemotherapy or radiation, we believe it would be more effective to use treatments targeted directly at these so-called cancer stem cells. If the stem cells were eliminated, the cancer would be unable to grow and spread to other locations in the body.
Commitment to Cancer Stem Cell Research
The U-M Comprehensive Cancer Center is one of only a few research institutions in the United States and Canada that has made an institutional commitment to cancer stem cell research.
Organized teams of U-M scientists are studying cancer stem cells in many different types of cancer:
- head and neck
- thyroid cancers
By working together and sharing information, Cancer Center scientists hope to make progress more rapidly than would be possible for individual scientists working alone.
We believe new treatments designed to target and destroy cancer stem cells could revolutionize the way physicians treat cancer. Our goal is to be the world's leader in research on cancer stem cells and in the development of new stem cell-based therapies for cancer patients.
What are stem cells?
Every organ and type of tissue in the body contains a small number of what scientists call "adult" or "tissue" stem cells. Since most cells in the body live for just a short time, the body needs to keep making new cells to replace them.
Adult stem cells ensure a continuous supply of new cells to replace old cells that wear out or are destroyed.
Stem cells have properties that make them different from ordinary cells.
- They divide
Stem cells can divide to make exact copies of themselves - a property scientists call self-renewal.
- They differentiate
Stem cells can differentiate to make specialized cells called progenitor cells that go on to form the organs and tissues in the human body.
- They duplicate
Every time a stem cell divides, it makes one exact copy and one progenitor cell. When the progenitor cell divides, it produces two cells that are somewhat more specialized. Each generation of new cells is more specialized than the previous generation until, eventually, mature cells are produced.
- They divide indefinitely
Many cells can divide to make copies of themselves, but they can only divide a certain number of times before they die. Stem cells can keep dividing indefinitely. Because stem cells are essentially immortal, the body keeps them under tight control, so they will divide only when a new supply of cells is needed.
What types of stem cells were discovered at the U-M Cancer Center?
In 2003, U-M scientists were the first in the world to identify cancer stem cells in a solid tumor, finding them in breast tumors. Since then, other Cancer Center scientists have discovered and isolated cancer stem cells in pancreatic cancer (2007), in head and neck cancer (2007) and in an aggressive brain cancer called glioblastoma (2009).
How do scientists identify cancer stem cells?
Scientists use several techniques to identify cancer stem cells
Even under a microscope, there's no way to distinguish cancer stem cells from other malignant cells just by looking at them. To identify stem cells, scientists use specialized equipment to detect specific proteins on the cell's surface.
These proteins are not found on regular cancer cells. A biochemical assay developed at the U-M Cancer Center can identify breast cancer stem cells.
The ultimate test to prove that cells are true cancer stem cells is to inject cells from a human tumor into mice that are genetically engineered to lack a cancer-fighting immune system. If the mouse does not get cancer, scientists know the injected cells were not stem cells, because ordinary tumor cells will divide a few times and then die. But if the mouse develops a tumor with the same types of cells as the human tumor, scientists know that the injected cells were true cancer stem cells.
Research on cancer stem cells will change everything about how doctors diagnose, prevent and treat cancer
Will the discovery of cancer stem cells change how doctors treat cancer?
By analyzing the genes that are active in a patient's cancer stem cells and counting the number of stem cells in a tumor, physicians could identify patients at high risk for advanced, aggressive disease.
New therapies designed to target stem cells could eliminate cancer without the risks and side effects of current treatments that also destroy healthy cells in the body. Destroying cancer stem cells in the original tumor could reduce the risk of deadly metastasis, where malignant cells move from the primary tumor to other places in the body. Finally, by killing the cells driving the tumor's growth, treatments targeted at cancer stem cells could eliminate recurrences of the disease.
Why doesn't chemotherapy and radiation kill cancer stem cells?
Scientists don't know for sure. Since chemotherapy and radiation kill cells that divide often, stem cells may be less vulnerable because they rarely divide. Some scientists believe cancer stem cells may have genetic mutations that make them resistant to damage from chemotherapy or radiation, or cancer stem cells may be able to repair DNA damage more rapidly than normal cells.