Viral gene therapy (similar to techniques used in the stem cell breakthrough last week) has been used by University of Texas MD Anderson Cancer Center researchers in animal models and reported in the September 19, 2007 issue of the Journal of the National Cancer Institute. From MD Anderson:
Since 2004 scientists have found that brain tumors are driven by haywire stem cells that replicate themselves, differentiate into other types of cells, and bear protein markers like normal stem cells.
“Research has shown that these cancer stem cells are the origin of the tumor, that they resist the chemotherapy and radiation that we give to our patients, and that they drive the renewed growth of the tumor after surgery,” Fueyo said. “So we decided to test Delta-24-RGD against glioma stem cells and tumors grown from them.”
Researchers used a virus to infect the cells of aggressive tumors of the cells that support brain cells, glioblastoma multiforme. Gliomablastomas are 60% of brain cancers and patients have a survival rate as short as 2 to 3 months, with less than 10%-25% survival after 2 years even with current aggressive therapy. The virus is modified so that it is “selective” for cancer: it only infects the cancer tumors and cannot infect others.
The team first developed mice with transplanted human brain cells derived from stem cells found in four samples of glioblastoma multiforme. The researchers then developed a customized virus, Delta-24-RGD, to fight the cancer. According to a 2003 MD Anderson press release on the trials, the virus infection inserts copies of a certain gene, retinoblastoma protein (Rb), that acts as a “brake” on the cell duplication system of the cell. In order to make the therapy more efficient and safer, the virus also insert a gene to for a cell surface receptor, a sort of “docking” area on the outside of the cell.
The cell surface receptor for viruses is one of the ways that we are studying to fight both cancers (see this free article from this month’s JNCI) and viral infections, themselves. The goal is vaccinations to affect genetic causes of cancer (as in these two reports) or to prevent viruses from binding to the cells and infecting them in the first place.