Written by Raymond Chu
Every year, salmonella is the cause of one million cases of food poisoning and nearly four hundred deaths [1]. It’s no wonder that just thinking about it makes our stomachs turn. But relax, salmonella can be useful too.
In recent news, several researchers from Duke University published their study in which they genetically engineered a strain of salmonella. This strain, known as Salmonella typhimurium, would usually target our gastrointestinal tract. However, when genetically engineered and modified, it can be used to target an aggressive type of brain tumor. This type of cancer, glioblastoma, leaves patients with a median survival period of fifteen months, even when they’re provided with the best possible current treatment [1]. As for the ten percent that do survive, their lives are usually prolonged for about five years [1].
Previously, effective treatment options were limited and progress was hindered. For example, drug-based treatments were nearly impossible due to the high selectivity of the blood-brain barrier. Surgical methods weren’t any better. If even a single cancer cell was left behind, it could result in new tumors. However, with advanced technology, researchers have been able to genetically alter the salmonella’s DNA to generate self-destructing abilities when inside the tumors.
For the purposes of the study, a strain of purine deficient Salmonella was used, as purine is a heterocyclic compound found in abundant quantities in tumors [1]. When the modified Salmonella was injected into the brain, they were able to penetrate the tumors to begin rapidly multiplying. While this happened, two compounds known as Azurian and p53 were produced and released in the tumor (a low-oxygen environment) to cause the cancer cells to self-destruct [1]. Ultimately, both of the tumors and Salmonella were killed. When treating the rats affected in the late stages of glioblastoma, the researchers found a twenty percent survival rate as seen the tumors were in remission for over one hundred days [2]. This is highly significant since it translates to roughly ten human years [2], which is double the survival rate before.
As of today, these studies have mainly been in the laboratory, and it is unclear if and whether they may proceed to clinical trials [2]. However, it does give hope that we can come up with creative approaches to tackling complex problems. The use of genetic engineering in therapeutics has and will continue to change the world of medicine.
References:
1) “Salmonella Has Been Genetically Engineered to Consume Brain Tumors.” Futurism. N.p., 16 Jan. 2017. Web. 29 Jan. 2017.
2) “Tumor-Seeking Salmonella Treats Brain Tumors.” Tumor-Seeking Salmonella Treats Brain Tumors | Duke Pratt School of Engineering. N.p., n.d. Web. 29 Jan. 2017.
3) “Development of Salmonella strains as cancer therapy agents and testing in tumor cell lines.” Methods in molecular biology (Clifton, N.J.). U.S. National Library of Medicine, n.d. Web. 29 Jan. 2017.