Cancer treatment breakthrough due to a bacteria species
By Emma Gruner, Staff Writer
In all of medical research, few fields have been plagued with as much frustration and angst as those involved with cancer.
A disease that invades from the inside of the body outwards, cancer afflicts so many people but is still difficult and to treat. It often seems as if cancer evolved solely to thwart humanity’s greatest minds.
Yet as our medical pioneers consistently show us, loopholes can always be found, sometimes in the most unlikely places. The most recent cancer breakthrough suggests that certain cancers could be defeated by the body’s very own immune system… with a little help from the Salmonella typhimurium bacterium.
As most people are aware, cancer is not like other diseases, in which the body becomes infected by foreign bacteria or viruses.
Instead, the body is attacked by its very own cells – cells that the immune system does not recognize as a threat. To overcome this hurdle, medical researchers have attempted to infect cancer cells with bacteria that the body does recognize. Sometimes, this method proves successful; in fact, there is currently an FDA-approved bladder cancer treatment that uses Mycobacterium bovis bacillus Calmette-Guérin (BCG). More often then not, though, such bacterial treatment proves ineffective in the long run, or else the bacteria themselves end up causing harmful side effects.
However, new research performed by Chonnam National University in Gwangju, South Korea suggests that humans may soon have another safe, effective bacterial treatment in their repertoire, this time involving Salmonella.
Although the findings were just published in Science Translational Medicine on Feb. 8, the project in question has actually been in development since 2006. At the time, Chonham researchers were attempting to develop a vaccine for Vibrio vulnificus, a bacteria that infects shellfish off of the Korean coast.
While working with the bacteria, the team noticed that a certain protein secreted by the Vibrio flagella – known as flagellin B or FlaB – initiated a particularly strong response from immune cells by activating secondary molecule TLR5, making the cells more aggressive. Realizing the potential this protein could have for cancer treatment, the researchers modified a harmless version of Salmonella to secrete FlaB in response to a sugar signal.
To test this new Salmonella “weapon”, the team, led by Jung-Joon Min and Joon Hueng Rhee, injected the bacteria into 20 mice, all of which had already been infected with human colon cancer.
Like most bacteria, Salmonella has an affinity for necrotic, oxygen-depleted cells, causing them to colonize the tumorous tissues within three days. After 120 days, 11 out of the 20 treated mice had no detectable tumors; those in a control group treated with non-FlaB secreting bacteria eventually succumbed to their cancers.
Having established this connection, the Korean researchers decided to take their project one step further. In the next round, they once again injected the modified Salmonella into cancer-stricken mice, although this time, the cancer was already in the process of metastasizing.
Out of the eight mice that were treated in this manner, five were completely tumor-free after 27 days, while the remaining three had only four relatively small tumors among them.
By contrast, the six mice treated with non-FlaB secreting bacteria and the seven that remained completely untreated had a total of 91 metastasized tumors after the same time period. This study marks the first time that bacterial treatment has been shown to prevent tumor metastases, and, remarkably, the mice displayed no serious side effects.
Of course, this research is far from complete. With only several, small-scale animal treatments under their belt, the team plans to continue refining their technique for several years. Ultimately, Min and Rhee hope to run clinical trials in humans to verify its safety and efficacy. Yet so far, the research appears incredibly promising, and to the medical community, this step brings us ever closer to the ultimate, elusive cure.