Cancer cells divide rapidly, and current gene therapy techniques can be used to inject genes into these cells. But not all cancer cells within a tumor divide at the same time. Current cancer therapies kill dividing cells, but dormant cells can divide after treatment, causing the tumor to come back. The T7 system would allow scientists to inject a corrective gene into a tumor that would begin working immediately on dividing cells, then lie in wait for other cells that divide later. And, Wagner said, the system would not have the negative side effects of some current cancer treatments because only diseased cells are attacked.
Chemotherapy kills all cells on contact, even healthy cells.
The T7 system allows for a more selective treatment that targets only the cancer cells, leaving healthy cells untouched. The key to T7 lies in its ability to start the genetic process outside the nucleus. The system is loaded with everything it needs for gene expression, including materials similar to those found inside a cell's nucleus. The T7 system is used to inject DNA and T7 RNA polymerase into a region of tissue or muscle containing diseased cells. The DNA is taken up by the cells, and the genes begin to express in the cytoplasm.