GM Bacteria Light Up Tumors for Attack

Back at the turn of the last century, a surgeon noticed a remarkable correlation between cancer patients with Streptococci infections (erysipelas) and sudden remissions of their cancer tumors. Dr William Coley [photo] wrote about the strange correlation ans speculated that it might have something to do with the bacteria eliminating tumor cells. He began injecting patients with the bacteria, hoping to achieve the same remission he saw in other cases. He had some success, but also some patients died of sepsis (blood poisoning). Despite the initial success his idea faded with the advent of radiation therapy considered to be more controllable.

Now, in the age of nanobots and genetic modification of organisms, using bacteria as cancer fighting agents is getting a second look. Oncologists are always on the lookout for agents that can distinquish between normal cells and cancer cells in the body. Some bacteria will colonize tumors and leave the rest of the body alone. Motile bacteria are especially adapted to this function, as are those which can survive anerobic enviroments such as inside a tumor. Finding such bacteria is half the battle. Modifying them to destroys a tumor is the more difficult part of the problem. 

Research is starting to bear fruit. Scientist have reported a modified probiotic bacteria used in conjunction with human T-cells seems to work. Rather than introduce a toxin into the body, the modified bacteria give off a signal using the green florescent protein (GFP) modified to cause the protein to stick to the tumor's surface. The body's own immune system in the form of modified T-cells responds to this signal as an invader and begins attacking the tumor, which is a good thing since solid tumors are insidious, not giving the immune system an obvious indication of their presence. The bacterium literally explodes giving off a green flash. Its like a flare on a battlefield identifying the enemy's location.

Bacteria that are not harmful to the body and that have been genetically atenuated gives added protection to the patient. In one interesting experimental trial with mice, E. Coli Nissle 1917, a non-toxic bacterium, was modified and injected in mice with tumors modeling human brest cancer. Some mice were then treated with E. Coli having the GFP gene and a protein that attracts T-cells generally; some received bacteria with only the GFP gene and T-cells modified to recognize the GFP signal; the control group were injected with saline. The results are remarkable. Mice with the GPF gene had tumor growth of only 40%; mice treated with bacteria having both modifications had no tumor growth, while the control group had tumors that tripled in size because the strain of mouse used in the experiment has no active immune response.  Researchers looked for the engineered bacteria in other organs and found none; the bacteria are highly specific. Clinical trials are next. Dr. Coley's hunch a hundred fifty years was correct; only the proper tools had to be developed first.