Stem Cells and Cancer
Last Sunday the Philadelphia Inquirer printed an article about the possible role stem cells may play in causing cancer. While this is hardly reassuring for people to read about, it’s quite an important area of stem cell research, since for stem cell treatment to be a successful therapy, it must not cause tumors. Understanding the relationship between naturally occurring stem cells and cancer helps with both cancer research and the ongoing research of stem cells (of all types) as therapeutic. And, since stem cells’ function is to create new tissue, it is hardly surprising that sometimes things go wrong. Stem cells normally die off after a certain period of time, but in cancers they may continue to divide. Full text of the article
can be found on the Inquirer’s website.
According to the article, scientists have found that “rogue” stem cells within human blood, breast, and brain cancers cause cancers when transplanted into mice. The stem cells are slow-growing, especially compared to the rapid growth of a tumor, and chemotherapy is designed to kill the rapidly dividing cells. This might explain why cancer often recurs; the stem cells at the root are not killed by chemotherapy.
One example is leukemia. In the 1990’s researchers discovered that it took massive injections of leukemia cancer cells into a subject animal for a new cancer to begin; the individual cancer cells were not capable of proliferating extensively on their own. In 1994, the researchers identified what appeared to be a normal healthy stem cell that had “turned renegade” and caused acute myelogenous leukemia. It was already known that “defective” stem cells in the bone marrow caused the excess of white blood cells that is leukemia.
The relationship between stem cells and solid tumors, however, has taken much longer to unfold. In 1987 research showing stem cells have a role in cancer development was done by not widely accepted by the scientific community. However, in the last few years, many more studies have been done which identify stem cells as causing tumors. The Inquirer article cites work done isolating tumor stem cells in breast cancer, a study identifying tumor stem cells in brain cancer, and a link between gastric cancer and bone marrow cells. Research is now progressing in a number of areas, including why the stem cells don’t die off as they normally would.
For patients with cancer, the treatment options may need to be changed; chemotherapy administered after the cancer has apparently been wiped out might kill stem cells which have entered a period of rapid division to create a new cancer.
Stanford University has a Q&A on the Institute for Cancer/Stem Cell Biology and Medicine
which has a lot of useful information about stem cell research. According to the site, "A primary goal of the institute is to use this knowledge to help treat cancer and to understand the processes involved in cancer development." Good info here for people interested in stem cells and cancer, or just in stem cells.