There is more hard evidence coming in to support the notion that if we want to get somewhere with preventing and curing cancers, the best approach invoves broadening focus from what is going on inside and among cancer cells to also include what is going on inside and among cancer stem cells. For background, see the July 6 blog post On Cancer stem cells.
In fact, going back to when I was just starting this blog, in the february 5 post From four-pound hammer to smart molecules – on cancer treatments, I said “The idea is to discover genetics-based and bio-molecular therapies which go after and kill the cancer stem cells, turning off the source of new cancer cells. “New therapies designed to target stem cells could eliminate cancer without the risks and side effects of current treatments that also destroy healthy cells in the body. Destroying cancer stem cells in the original tumor could reduce the risk of deadly metastasis, where malignant cells move from the primary tumor to other places in the body. Finally, by killing the cells driving the tumor’s growth, treatments targeted at cancer stem cells could eliminate recurrences of the disease(ref).” The hope is for approaches that prevent or cure cancers that work by killing cancer stem cells, or causing them revert to benign form or preventing their differentiation into cancer cells.
The new research reported yesterday in the world press shows two advances with respect to cancer stem cells (CSCs): first, development of a high-throughput screening approach for agents that have high toxicity for epithelial cancer stem cells; second, identification of a compound that has very high toxicity for breast cancer stem cells. “A critical aspect of our work was to generate relatively homogenous and stable populations of cancer stem-like cells that could then be used for screening,” says Tamer Onder, — co-first author of the study(ref).” “The technique works by coaxing adult cells to undergo a critical change (known as an “epithelial-to-mesenchymal transition”) that alters their shape and motility. At the same time, the cells also adopt similar properties as stem cells(ref).”
Of the 16,000 chemical compounds tested, only a small subset showed toxicity against cancer stem cells. One particular substance, salinomycin, showed high toxicity. “– salinomycin, reduces the proportion of CSCs by >100-fold relative to paclitaxel, a commonly used breast cancer chemotherapeutic drug. Treatment of mice with salinomycin inhibits mammary tumor growth in vivo and induces increased epithelial differentiation of tumor cells. In addition, global gene expression analyses show that salinomycin treatment results in the loss of expression of breast CSC genes previously identified by analyses of breast tissues isolated directly from patients(ref)” “Salinomycin is an ionophore antibiotic used in farming for the prevention of coccidiodomycosis in poultry and to alter gut flora in order to improve nutrient absorption in ruminants(ref).”
Of course, there is a long road of clinical trials that must be traveresed before salinomycin can be used for treating humans with breast cancer. In an important recent post in this blog, I suggested that there was an important new way to look at aging: to focus not only on what goes on with normal body cells but also on what is happening with the stem cells in the supply chain that replenishes those body cells. The same holds when it comes to cancers.