Recent studies have shown that mutations in the DNA of adult stem cells can lead to the formation of cancerous rather than normal tissues. However, with the exception of blood, adult stem cells are rare and not readily accessible for isolation or study. Thus, very little is yet known about how these stem cells are hijacked to cause cancer.
Our laboratory is studying how mutations in stem cells give rise to Ewing sarcoma. Ewing sarcoma family tumors (ESFT) are highly aggressive tumors that primarily affect children and young adults. ESFT have a specific mutation in their DNA that leads to the creation of a cancer-causing gene called EWS-FLI1. It is our hypothesis that expression of EWS-FLI1 in adult stem cells generates ESFT. In particular, we are interested in a very rare population of adult stem cells called neural crest stem cells (NCSC) and these cells have been the focus of our CIRM-funded grant.
We initially proposed that human embryonic stem cells (hESC) could be used to generate NCSC and that these cells would be invaluable tools with which to study the origin of ESFT. In the first year of the grant we successfully achieved this goal and the work has been published. In the second year of the grant we have studied the consequences of activating the EWS-FLI1 on these cells. Importantly, our work shows that NCSC that express EWS-FLI1 do not differentiate normally. Instead they acquire properties of cancer stem cells. Thus, we propose that ESFT arise from NCSC that acquire a genetic mutation that prevents them from developing normally. These abnormal stem cells then go on to develop into full blown tumors.
By creating novel stem cell models to study the origin of ESFT we are gaining new insights into how these tumors arise in children. These insights will ultimately aid in the development of more effective therapies that can be designed to destroy abnormal cancer-causing stem cells whilst sparing normal stem cells.