Gene therapy represents a new approach in cancer treatment, which is currently still experimental. Since knowing that cancer is a disease caused by gene mutations, researchers began to think that gene therapy would be effective to treat it. Moreover, many more cancer sufferers compared with a hereditary disease caused by a genetic disorder that had been treated with gene therapy.
Currently scientists are trying to work some way of gene therapy for cancer treatment:
Adding a healthy gene in cells that have defective genes or incomplete. For example, healthy cells have a "tumor suppressor genes" such as p53 that prevents the occurrence of cancer. After investigation, it turns out in most cancer cells the p53 gene is damaged or even absent. By inserting a normal p53 gene into cancer cells, these cells are expected to be normal and healthy again.
Currently scientists are trying to work some way of gene therapy for cancer treatment:
Adding a healthy gene in cells that have defective genes or incomplete. For example, healthy cells have a "tumor suppressor genes" such as p53 that prevents the occurrence of cancer. After investigation, it turns out in most cancer cells the p53 gene is damaged or even absent. By inserting a normal p53 gene into cancer cells, these cells are expected to be normal and healthy again.
Stopping the activity of "cancer genes" (oncogenes). "Cancer gene" is the result of mutation of normal cells, which causes these cells to divide wildly into cancer. There are also genes that cause cancer cells to metastasis (spread) to other body parts. Stopping the activity of this gene or protein formation, can prevent the cancer grow and spread.
Adding certain genes in cancer cells so it is more sensitive to chemotherapy or radiation, or the blocking of gene action that can make cancer cells resistant to chemotherapeutic drugs. Also tried another way, making healthy cells more resistant to high-dose chemotherapy, so it does not cause side effects.
Adding a particular gene so that tumor cells / cancer is more easily recognized and destroyed by the immune system. Or vice versa, adding a gene in immune cells, making them easier to detect and destroy cancer cells.
Stopping a gene that plays a role in tissue formation of new blood vessels (angiogenesis) or adding a gene that can prevent angiogenesis. If the blood supply and the food stops, cancers will stop growing or even shrink and die.
Deliver genes that activate a certain toxic proteins in cancer cells, so that the cells perform an act of "suicide" (apoptosis).
Virus Service
The problem is, how to insert the desired genes into target cells. Because so far the work directly inserted a gene into the cells is still not possible. Must use the services of an intermediary (vector), ie the virus. Yes, a virus. The virus has a better ability to recognize certain cells, penetrate into and transferring genetic material into it (that's how the infecting virus in the disease into a person's body).
Broadly speaking there are two ways commonly used to insert new genes into cells. The first, ex vivo. Most of the blood or bone marrow cells the patient is taken to be cultured in the laboratory. The cell was given a new viral gene carriers. Viral entry into cells and "fired" the new gene into the target cell's DNA chain.
Cultured cells are still a few moments longer in the laboratory. Once the gene completely fused with the cell, then the cells were returned to the patient's body by injection into a vein.
The second, in vivo. Viral gene carriers injected into the patient's body. Viruses that have been programmed to seek and attack the targeted cells (cancer) by firing the new genes carried into cells. The role of the virus is sometimes replaced by a liposome or an artificial plasmid as a vector.
There are various types of viruses used for gene therapy trials, such as retroviruses, adenoviruses, herpes viruses, pox, and others. Each has advantages and disadvantages. Prior to use all engineered in advance so as not capable of infecting the disease, as well as enhanced ability to recognize and enter target cells, as well as transfer genes.
Even giving great hope, and even some cancers have dared to make RS flagship therapy, this therapy can also cause problems. Because the virus can attack more than one type of cells, if injected into the body could have the virus enters the cells of the body, not just the cancer cells as expected.
Or, if the transferred gene attached to the wrong location in the DNA chain, this can cause dangerous mutations, and even new types of cancer. If the gene is "false targets" on the reproductive cells, then this mutation will be deployed also in the offspring of the patient, if later the patient had children.
There is also the possibility that transferred genes are overreacting in his new environment (cancer cells) so that even cause inflammation, or trigger a defense reaction / resistance of cancer cells. How well have engineered a virus that is infectious to others even healthy?
Scientists are constantly looking for ways to secure and deliver the most optimum results in accordance with the conditions of different patients. (Edict Rahayu / rumahkanker.com)
