An international research team led by Timothy C. Wang from Columbia University identified a new cancer-initiating stem cell population in the colon and intestine. The study entitled “Krt19+/Lgr5– Cells Are Radio resistant Cancer-Initiating Stem Cells in the Colon and Intestine” was published in the journal Cell Stem Cell.
Despite the decreased death rates as a consequence of colorectal cancer over the last 20 years, this malignancy is still the third leading cause of cancer death worldwide. The small intestine and colon epithelia are continuously renewing due to a local population of adult tissue stem cells, which are characterized by multipotentiality and the capacity to self-renew.
This research team had previously identified a radiation-sensitive population (Lrg5+) within stem cells that could give rise to colonic tumors. Now, they have identified, in a different region of the epithelium, a new tissue stem cell population able to originate colon cancer. These stem cells express intermediate filament keratin-19 (Krt19) but no Lrg5 (Krt19+/Lgr5– cells). Compared to the previously identified stem cell population, these cells are long-living and more resistant to radiation. Moreover, the research team observed that genetically modified mice expressing this cell population developed many colonic and intestinal tumors that were not eliminated by radiation.
‘The identification of more than one stem cell pool in the colon has proven challenging,’ stressed Samuel Asfaha, the first author of the study. ‘These findings are exciting as we have identified an important new target for cancer therapy. It is also proof that more than one stem cell can give rise to and sustain tumors, telling us that our cancer therapy needs to target more than one stem cell pool,’ he added in a press release.
These findings contribute to the understanding of colon cancer in humans, and may hold important clinical relevance for future colon cancer therapy. So far, based on the previously identified stem cell population linked to colon cancer, physicians believed that radiation therapy was effective. ‘With this new information, we now know this is not always true and we must find new forms of therapy to target the disease,’ says Asfaha.