A profound discovery has just been announced regarding breast cancer tumor cells which will impact the techniques that researchers have traditionally used to target cancer cells. A study conducted by doctors Michael F. Clarke and Max S. Wicha at the University of Michigan in Ann Arbor refutes the initial notion that cancer grows exponentially as a collection of cells. Instead, Clarke and Wicha discovered that only a small population of cells within a tumor were able to create tumors by developing into different types of cells present in a tumor. According to Dr. Clarke, this small population of cells resemble the adult stem cell because they are able to “make copies of themselves – a process called self-renewal – and produce all the other kinds of cells in the original tumor. Similar cells have been identified in leukemia in humans, but these are the first to be found in solid tumors.”
BABCN found out that in this study Clarke and Wicha examined cells from nine human breast tumors. In order to distinguish the cells, the researchers looked for proteins attached to the outside of specific cells. Using these proteins as “markers,” the researchers grouped the tumor cells into two different classes which they inserted into the mammary glands of mice. Tumors developed when they inserted 200 of one class of cells. No tumors developed when they injected 10,000 of the second class of cells. When a tumor developed in a mouse, the researchers isolated the cells into the same two categories and injected these cells into another mouse. Dr. Clarke noted that upon repeating this process four times, “tumor cells with this particular surface marker pattern [cells in class one] produced a new tumor in the next generation of mouse every time.”
Robert A. Wienberg of the Whitehead Institute for Biomedical Research, an early pioneer in the study of cancer-causing genes, believes that this study “creates a whole new conceptual paradigm on how tumors form” and that “it has profound implications for how we think tumors evolve and how we treat tumors.” Although conventional therapies effectively destroy the majority of cells within a tumor, they may miss some cancer cells that could be of the tumor stem cell class, thus facilitating cancerous tumors to recur. Dr. Wicha points out that “for the first time we can define what we believe are the important cells – the cells which determine whether the cancer will come back or be cured. Before this, we didn’t even know there were such cells.”
The direction of developing new cancer treatments may now be focused upon these stem cells. Unfortunately, because stem cells are less mature they are able to resist chemotherapy drugs more easily than mature cells. “Stem cells are more difficult to kill. Because they are so important throughout a person’s lifetime, they have developed mechanisms that protect themselves,” Dr. Wicha explains.
Although the researchers agreed that their work is some steps away from clinical use, they hope to find pathways to target the cancer causing stem cells this year. “Now that we can actually identify them, we can start developing treatments to specifically target and hopefully eliminate them,” expressed Dr. Wicha. However, Dr. Clarke indicated that finding the chemicals to attack the cells and developing ways to use them could take five to ten years.