Dr. Jeremy Rich, a cancer stem cell researcher at Duke University Medical Center, said, "The exciting thing is they have done things others haven't, which is to ask what is the impact of the marker on disease. First, there is an increase in ABCB5 levels as malignancy increases, and second, if you block its function with an antibody, you slow the growth of these tumors."
The results were published in the Jan. 17 issue of Nature.
According to the American Cancer Society, there were an estimated 108,230 new cases of melanoma in 2007 and 8,110 deaths.
The cancer stem cell hypothesis posits that tumors (like other noncancerous tissues) derive from a small population of primitive cells, which can divide and differentiate to form both the bulk of the cancer, and also more stem cells. Because most chemotherapeutic agents kill off the tumor cells, but leave the stem cells unscathed, the cancers return and metastasize.
The bottom line, according to the researchers, is that anti-cancer strategies need to be overhauled to kill off these stem cells.
Previous cancer stem cell studies have focused on the protein CD133. But it is not clear whether CD133 plays a role in stem cell behavior. According to Rich, such markers have sometimes been compared to the stripes painted on race cars: They do not make the car go faster, but they do help to identify it.
"This time, they have found a marker that is very interesting, because it looks like it may make the car go faster," he noted.
Also interesting, Frank noted, is the potential involvement of ABCB5 in mediating the cancer's resistance to chemotherapeutic agents.
"The findings establish a direct relationship between cancer stem cells, cancer progression, and chem
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