Glioblastoma, a form of brain cancer, is one of the most dreaded cancer diagnoses. Standard radiation and chemotherapy treatments for glioblastoma almost always prove ineffective because of the cancer’s ability to grow back. With their unlimited potential to self-renew, cancer stem cells within the brain tumor are thought to be responsible for its aggressive reoccurrence. Not surprisingly, researchers looking to develop more effective therapies are focused on trying to better understand the biology of these cancer stem cells in order to exploit their vulnerabilities.
This week, the Dartmouth-Hitchcock Medical Center reports that a research team led by Damian A. Almiron Bonnin has identified a cell signal that the brain cancer stem cells rely on to resist standard treatments and to regrow. They also showed that drugs which interrupt this signal reduced tumor growth in animal studies.
Because if its aggressive growth, the cells within the glioblastoma eventually become starved for oxygen or, in scientific lingo, they become hypoxic. The presence of hypoxia in brain tumors is actually predictive of a poor prognosis in affected patients. A protein called hypoxia-inducible factor (HIF) becomes activated in these low oxygen conditions and helps the cancer stem cells to survive and continue to grow. The research team found that HIF carries out this function by triggering a cascade of cell activity that leads to the secretion of a protein called VEGF out into the microenvironment of the tumor. As secreted VEGF spreads through the tumor, it stimulates new blood vessel growth which is key to the tumor’s survival by nourishing the tumor with oxygen and nutrients.
Adding drugs that block a cell’s ability to release proteins, led to a reduction in glioblastoma tumor growth both in petri dishes and in animal studies. With these results, published in Oncogene, Dr. Almiron Bonnin’s team is performing the necessary preclinical studies that could lead to testing this novel strategy in patients. He summed this effort in a press release:
“Being able to target the cancer stem cells within these tumors, like we did here, could potentially improve response to current chemotherapies and prevent recurrences, which would translate into an increase in patient survival rates.”