Researchers at the University of California- San Diego have recently developed a method in which they can deliver genes directly to the site of a tumor in the brain. As of right now, the technique has only been used in the treatment of glioblastoma, a potentially debilitating cancer that generally results in death within 14 months. This type of cancer has a high rate of recurrence and tends to develop deep in the brain, increasing risks associated with surgery.
When many people hear the term gene therapy, they tend to disregard it as "too science-y for comprehension", although it is a fairly straightforward technique to anyone who has a basic understanding of cell biology. In its simplest terms, gene therapy is treating a person by inserting genes (segments of DNA that code for a polypeptides, the building blocks of proteins) into a cell. The most efficient way to do this is by placing the gene into a virus which then inserts the gene into the cell.
Viruses are made up of 3 main components: A core of DNA or RNA (portions that carry information), a protein capsid (helps stabilize and protect the DNA/RNA), and attachment spikes (help attach to specific cells). In addition to these three components, many animal viruses also have a membrane associated with them that allows for fusion with the cell membrane. A virus works by attaching its spikes to proteins on the surface of the cell membrane. The attachment is very specific- down to certain types of cells within a particular tissue of a particular species. Once the spikes attach to the membrane, the capsid containing the DNA/RNA is brought into the cell and the contents are released. The information in the DNA/RNA is then utilized to build particular proteins.
When many people hear the term gene therapy, they tend to disregard it as "too science-y for comprehension", although it is a fairly straightforward technique to anyone who has a basic understanding of cell biology. In its simplest terms, gene therapy is treating a person by inserting genes (segments of DNA that code for a polypeptides, the building blocks of proteins) into a cell. The most efficient way to do this is by placing the gene into a virus which then inserts the gene into the cell.
Viruses are made up of 3 main components: A core of DNA or RNA (portions that carry information), a protein capsid (helps stabilize and protect the DNA/RNA), and attachment spikes (help attach to specific cells). In addition to these three components, many animal viruses also have a membrane associated with them that allows for fusion with the cell membrane. A virus works by attaching its spikes to proteins on the surface of the cell membrane. The attachment is very specific- down to certain types of cells within a particular tissue of a particular species. Once the spikes attach to the membrane, the capsid containing the DNA/RNA is brought into the cell and the contents are released. The information in the DNA/RNA is then utilized to build particular proteins.
If it's been a while since your last biology class, it may be beneficial to review the process of how DNA codes for traits. Follow along with the picture to the right. DNA is in the nucleus and stays there throughout the life of the cell. DNA codes for RNA through a process called transcription which occurs in the nucleus. RNA then moves out of the nucleus into the cytoplasm and to a complex called a ribosome. The RNA is fed through the ribosome which translates the RNA into a specific sequence of amino acids. Amino acids are then linked together to form polypeptides. Polypeptides then interact with each other to form a functional polypeptides, otherwise known as a proteins. Proteins are what cause your hair to be curly or straight, your eyes to be brown or blue, your brain, breasts, or prostate to develop genetically predisposed tumors or not...
In the case of gene therapy, when a gene is inserted via a virus it can cause new proteins, therefore new functions, to be produced by the cell. So for a type one diabetic, this could mean the pancreas can now make insulin. For a congenitally blind person, this could mean that the retina can now produce rods and cones for visual stimulation. In the case of this study, the researchers injected a virus which would cause a patient to produce a protein that turns a relatively innocuous chemical into a cancer fighting agent.
When the virus is injected into the tumor, it ensures delivery into the site of cancerous cells. The cells then produce this new protein. The function of this protein is to bind to an anti-fungal drug and make a small change. The change causes it to affect cancer cells rather than fungal cells. So, treating the cancer is a two step process, similar to the two steps used in the chemical reaction to make epoxy. Step 1, insert the gene. Step 2, orally take the harmless anti-fungal drug. The two interact with each other to destroy the tumor without the need for surgical removal.
Although this is technique is currently only being used in trials for treatment of glioblastoma, its results may have profound implications. The use of this two step technique could be a way to increase treatment specificity to target areas of cancer for treatment, reducing debilitating side effects associated with traditional treatments such as chemotherapy and radiation.
- Mark Sherman
Although this is technique is currently only being used in trials for treatment of glioblastoma, its results may have profound implications. The use of this two step technique could be a way to increase treatment specificity to target areas of cancer for treatment, reducing debilitating side effects associated with traditional treatments such as chemotherapy and radiation.
- Mark Sherman