Are Stem Cells a Magic Bullet for Cancer?
Can Science and Medicine Alter These Adult to Mimic Embryonic Genes?
Jan 15, 2009
Although there have been many successes in treating cancer over the years, side effects were almost as debilitating as the disease. Radiation and chemotherapy were meant to kill as many cancer cells as possible since it was assumed any remaining in the body could cause return of the cancer.
Cancer Stem Cells
In a few cancers, however, it is now known that the ability to regenerate the malignancy belongs to only a very few specific cells. Because their similarities to stem cells have been shown in stem cell research, they are now commonly referred to as cancer stem cells.
Observations in the medical field seem to corroborate the cancer stem cell theory. If a patient’s tumor after chemotherapy has only mature-appearing cells, the tumor normally will not come back. Only if numerous immature cells (undifferentiated) still appear will the risk of the tumor’s return increase.
Although adult stem cells are found in organs in the body, they are limited to producing either more stem cells or only for repair to that organ. For this reason, embryonic stem cells are the most useful. These do not differentiate, producing not only their own type (self-renewal), but also all other functioning (differentiated) cells of the body (pluripotent). The ethical questions involved from their use have slowed research.
Adult Stem Cells into iPS
However, Japanese researchers determined that specialized (differentiated) and embryonic stem cells have identical sets of genes. The difference is that some are turned on and some off. In 2007, teams from Kyoto University, the University of Wisconsin, and Harvard turned on four human skin-cell genes which reverted to embryonic-like stem cells (called iPS or induced pluripotent stem cells).
Although iPS cells have been used to successfully treat sickle-cell anemia in mice and Parkinson’s disease in rats, this only raises the possibility that they work in humans. In addition, two of the genes turned on are oncogenes (cancer potential) and a retrovirus used for transport into the specialized cell also could turn the iPS cells cancerous.
Questions to be Resolved
Many questions remain to be answered. Would laboratory-created iPS stem cells hone in on a diseased body organ? Would it then “cooperate” with healthy cells there? If it became part of another organ, would it cause damage? Could specialized adult cells be changed into a different type in another way? Finally, are we messing with nature and creating more problems?
As with most new developments, further research on animals and humans is necessary. Watch for future possibilities in this area for cancer, as well as other diseases. In the meantime, remember there is no magic bullet. As your mother would say, keep eating your fruits and vegetables, and move that body!
Bibliography:
Clark, Michael F., Becker, Michael W., “Stem Cells: The Real Culprits in Cancer?, Scientific American, July 2006, Page 53
Scadden MD, David T., Komaroff MD, Anthony L, Will stem Cells Finally Deliver?, Newsweek, December 15 2008, Page 57
