Cancer Stem Cells

Cancer stem cells are actually right at the heart of the history of stem cell research as these were the cells which led to the discovery of embryonic stem cells back in the 1970s. Researchers Gail Martin and Martin Evans were working together in England, trying to determine ways of controlling cancer cells and to keep them alive so as to better understand how to destroy them. Cancer tumor cells are actually often very similar to stem cells in terms of cell division and control and when Martin and Evans were looking at these cancer cells they observed them clumping together and forming specialized heart cells, muscle cells, and other cell types. This, they reasoned, could mean that cancer cells were actually similar to stem cells behaving dysfunctionally, and thus the search for embryonic stem cells began.

Cancer Cells’ Role in Embryonic Stem Cell Discovery

Martin continued her work, in California this time, and tried to develop a technique to culture cells taken from mice embryos. After limited success she hit upon the idea of using a chemical nutrient medium with tumor cells to kick-start the growth of the embryonic cells and in 1981 this was done successfully and ‘embryonic stem cells’ were christened. Evans, on the other side of the Atlantic, also found a way of keeping the embryos’ cells alive and continuing to grow by maintaining their presence inside the uterus of the mouse but preventing implantation. After a few days the embryonic cell mass was large enough to remove in order to extract the stem cells whilst preventing their differentiation, thus giving scientists an almost inexhaustible line of embryonic stem cells for research purposes.

Cancer Stem Cells and Teratomas

The cancer cells that Martin and Evans were studying in the 1970s were actually teratoma cells which make up a rare type of cancerous tumor that occurs in the testes or the ovaries, although they can occur elsewhere in the body. These cancer stem cells are almost mirror images of the embryonic stem cells which go on to create new individuals and it is these cells that prompted the researchers to imagine that there must be a healthy version of the cancer stem cells which would behave in this way. Teratomas have been found which contain beating heart cells, portions of hair, and bone, and even small teeth as these are essentially embryonic stem cells gone wrong.

Cancer Genes and Stem Cells

Considerable resources are currently being used to investigate the reasons that cancer stem cells occur in opposition to healthy stem cells and, in April 2011, researchers at the National Human Genome Research Institute released a paper detailing newly discovered genes involved in the progression of cells to melanoma, the deadliest form of skin cancer. Funded by the National Institutes of Health, the scientists mapped the melanoma genome and made surprising new discoveries about the origins of cancer. Over-exposure to the sun is thought a major factor in skin cancer development and this is due to the DNA damage incurred due to ultraviolet radiation. The genetic mutations which occur as a result of this DNA damage can then lead to skin cancer. In developing a more thorough understanding of the type of genetic damage which leads to cancer, more efficient and accurate methods of detecting cancer and treating the disease may be developed, including the potential for stem cells themselves to be used as vehicles for targeted cancer cell destruction.

Cancer Stem Cell Research

This research revealed 68 genetic changes that were thought to be somatically mutated at elevated frequency in the samples studied. Sixteen genes were then isolated as drivers of melanoma mutations, only one of which was already implicated in melanoma, giving researchers a number of new markers for cancer detection and increasingly targeted treatment potential. The discovery of these oncogenes (those which allow a cell to survive stressful conditions rather than die off normally) does not mean that new treatments or diagnostic procedures are likely to be available any time soon, but the research does allow scientists to focus further research in areas likely to be more beneficial for developing such techniques.

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