Colon cancer could join the growing list of stem cell-related cancers with the discovery of a population of highly tumorigenic primary human colon tumor cells, according to researchers from Biogen Idec.
“Such stem cells could be responsible for the perpetuation of colon cancer and its relapse following successful therapy,” said Peter Chu, Ph.D., researcher at Biogen Idec. “Our goal is to improve cancer survival rates by identifying these cancer stem cells in order to pave the way for therapeutics to prevent the relapse or metastasis of cancer.”
To identify potential cancer stem cells, also known as cancer-initiating cells, the researchers screened a population of human colon cancer cells for molecular markers that differentiated some cells from others. They found a certain subset of cells produced an exceptional amount of CD44 cell surface receptor protein, a well-studied protein involved in many forms of cancer.
According to Chu, to be identified as cancer stem cells, they had to be highly tumorigenic, creating new tumors quickly and from very few starting cells; had to be self-renewing, possessing a capacity to regenerate; and they had to produce tumors similar to the tumor of origin. “These CD44-producing cells fit the bill, although there is evidence to believe that CD44 overexpression is not the sole marker for colon cancer stem cells,” said Chu.
Chu and his colleagues discovered that as few as 10 cells producing high amounts of CD44 were capable of creating tumors in an animal model. In contrast, other tumor cells were 10 to 50 times less tumorigenic. The fact that they were tumorigenic at all, the researchers say, indicates that CD44 alone is unlikely to be the sole indicator of stem cell-ness among the tumor cell population. However, according to Chu, the discovery that high CD44 producing cells have cancer stem cell properties provides an entry point into further research into cancer-causing stem cells.