A nontoxic chemical extracted from milk thistle, a purple flower that grows around the world, may help stop the growth of colon cancer stem cells. Silibinin, the purified chemical, was shown to reduce the number of cancer stem cells in mice when the animals were fed silibinin.
“We have been deeply involved in this line of research that extends from silibinin to its chemopreventive properties in colorectal cancer, and the current study takes another important step: we see both a likely chemopreventive and a therapeutic mechanism and the result of this mechanism in animal models,” said Sushil Kumar, PhD, a postdoctoral fellow in Dr. Rajesh Agarwal’s laboratory at Colorado University Cancer Center. Dr. Kumar was the lead author on a poster presentation given at the American Association for Cancer Research Annual Meeting held this week.
The research team from Colorado University fed mice 200 mg/kg of silibinin 24 hours after injection of colon cancer stem cells into the animals. Tumor growth, measured by visible size, and tumor metabolism, measured by glucose use, were the main metrics used to determine the effectiveness of treatment.
Mice that were fed silibinin experienced a slower progression of disease, while unprotected mice saw large increases in tumor size and volume. The experiments were then extended to isolate injected colon cancer stem cells from one mouse and reinject the cells into another mouse to further explore the cancer-fighting capacity of silibinin. “Importantly, when these cancer stem cells from tumors in mice fed silibinin were re-injected into new mice, we found these stem cells had lost their potential to repopulate even in the absence of silibinin exposure,” said Dr. Agarwal in a news release from the university.
“It’s very simple: tumors from mice that were initially fed silibinin had fewer cancer stem cells, were smaller, had lower metabolisms and showed decreased growth of new blood vessels,” said Dr. Agarwal. The poster, entitled “Oral Silibinin Inhibits Tumorigenic Potential of Colon Cancer Stem Cells,” demonstrated the tumorigenic potential of silibinin on treating colon cancer cells, supporting further development of anti-cancer therapeutics that target tumor stem cells and reduce the aggressiveness of disease.