Some cancers are particularly aggressive and metastasize – spread to other areas of the body and form secondary cancers. The cancer cells associated with metastasis and more aggressive tumors are cancer stem cells. Even after patients have been successfully treated with chemotherapy or radiation therapy, cancer stems cells can give rise to secondary tumors.
Cancer stem cells have greater longevity and continue to migrate after treatment via the blood stream, and even after the primary site has been treated, sometimes years later, secondary tumors form from the cancer stem cells that are not killed by the treatments. Those tumors tend to be much harder to treat.
Currently there are no drugs available that can specifically target these aggressive cancer stem cells. Part of the problem in that respect is that it has not been possible to isolate the cells, and therefore treatments have not been developed to specifically target those cancer stem cells.
If aggressive cancer stem cells could be isolated, it would allow researchers to search for compounds that specifically killed the cells, thus reducing the risk of secondary tumors forming. However, isolating cancer stem cells has proved to be a major challenge.
Now a team of researchers for the University of Texas have developed a technique that allows them to isolate the cancer stem cells and differentiate them from other cancer cells.
The researchers tested more than 40,000 chemicals in their search for a compound that would selectively bind to the stem cells, but not other cancer cells. From those 40,000 chemicals, the researchers identified five that would selectively bind to the cancer stem cells, and the most promising compound was selected for further analysis.
The compound – or ligand – was coated on 40,000 tiny plastic beads which were mixed with breast cancer cells and breast cancer stem cells. The researchers found the ligand bonded only with the stem cells, allowing them to be separated. Those stem cells were injected into a group of mice, while the non-stem cells were injected into a second group. Mice injected with the cancer stem cells developed aggressive tumors, while those injected with the non-cancer stem cells did not.
Now that the cells can be isolated, researchers have an opportunity to develop drugs that specifically target those aggressive cells.
The research is detailed in the paper – A Synthetic Binder of Breast Cancer Stem Cells – a source of biomarkers for clinical diagnosis – recently published in Chemistry – A European Journal.