Mesothelioma Treatment with Gene Therapy
Researchers are continually searching for new therapies to treat mesothelioma. One of these new treatments that holds great promise for the future, according to the American Cancer Society, is gene therapy. However, at the present time, gene therapy is only available through participation in a clinical trial.
The term “gene therapy” actually encompasses a number of methods of altering the structure or function of genes by inserting DNA or RNA into cells to restore a function that has been lost, or to change a cell function:
- Replacing defective p53 genes. These suppress tumor growth. Adding a functioning copy of the p53 gene into cancer cells may make it possible to control the growth of these cells.
- Stopping oncogenes from dividing and metastasizing. Oncogenes are mutations of normal genes that speed up cell division, causing cancer to spread.
- Making cancer cells more unstable. Cancer cells lack the ability to repair faulty DNA, which allows them to grow and divide rapidly. By changing faulty genes so that normal cells can repair them, but cancer cells cannot, would allow for apoptosis or programmed cancer cell death.
- Changing cancer cells so they are more responsive to cancer treatments.
- Making tumor cells more visible and more vulnerable to the body’s immune system. This can be accomplished in two ways. First, adding a “tagging” gene to cancer cells, a process that makes them more identifiable so the immune system can recognize and destroy them. Second, adding genes to immune system cells to make them better able to identify cancer cells.
- Stopping genes that play a role in angiogenes, which is the formation of new blood vessels that carry nutrients to the cancer cells. Stopping the nutrient supply should cause tumors to shrink.
Scientists are experimenting with different methods of getting genes into targeted cancer cells. The first is called in vivo, which is Latin for “in the body.” This requires the physical placement of genes into the cancer cells. The biggest drawbacks of this technique are that tumors aren’t always accessible and in cancer that has metastasized, not all of the cells may be found.
The second technique is called ex vivo, which is Latin for “outside the body.” This would be accomplished by removing some of the targeted cancer cells from the body and adding the genes to them in a lab. These changed cells would then be placed back inside the body.
Another area of research associated with gene therapy is researching vectors, or vehicles that can transport genes into the targeted cells. Viruses are being considered as vectors because they inject their DNA or RNA into cells they infect, causing the cells to create proteins that are necessary for the reproduction of the virus cells. The gene to be transported would be put into the virus in the lab and harmful viral genetic material would be removed. The virus would be given to the patient so it could infect the cancer cells. However, these viruses could also trigger an immune system response, making them ineffective. In addition, they aren’t easily controlled, so they could insert themselves into a functioning gene, which would cause a mutation.
Another method is to use liposomes, the tiny fat molecules in the body. The liposomes would have pieces of DNA added to them in the lab. They would then be injected into the body so they could flow through the cell membrane and deposit their DNA pieces into the cells. Liposomescan carry larger genes, but they are less likely then viruses to end up inside the cells.