- A team of scientists and biologists from the Chonnam National University in Gwangju, South Korea have been able to use the deadly food poisoning microbe Salmonella to fight cancer
- They genetically modified the microbe and introduced it into human cancerous tumors which were then destroyed by the microbe
- While the team currently used murine (mouse) models, they soon plan to move into animal models as well as human clinical trials
Cancer cells are extremely tricky to target and destroy because it masquerades as the body's own cells and thereby making it invisible to the body's defense systems. The immune system misses the cancer cells mistaking it for its own cells. For long, scientists have tried various methods to trick the immune system into attacking cancer cells. Finally, there is a breakthrough as scientists were able to use the deadly food poisoning microbe Salmonella
to mount a powerful immune response against human cancer cells. This was first tried out in mouse models and successfully reduced the tumors and prevented metastasis. If replicated in humans, this could be a powerful treatment modality in bacterial cancer therapeutics.
Bacteria and Tumors
‘Food poisoning microbes like Salmonella could evolve into a key method for mounting an immune response against human cancer cells’
Most solid tumors in cancer present with necrotic, oxygen-deprived tissues. This is the gap with which scientists can work to use microbes in killing tumor cells. However, there is also a loophole where the cancer recurs and the bacteria itself turns toxic and destroys the good cells in the body.
is a group of bacteria causing typhoid,
, enteric fevers and other diseases. In the year 2006, scientists and biologists from the Chonnam National University in Gwangju, South Korea were in search of a novel cancer combative agent. Incidentally they were also looking to develop a vaccine for the bacterium, Vibrio vulnificus which is a deadly bacteria infecting shellfish on the South Korean coast. Working with Vibrio they found a protein in its flagellum which elicited a positive response from the immune system. The scientists then used the harmless version of Salmonella typhimurium
by genetically modifying it to secrete the protein FlaB. This protein is responsible for killing the tumor cells.
Biologists, Jung-Joon Min and Joon Haeng Rhee with the team injected modified Salmonella into 20 mice with human colon cancer. After three days, it was found that all the mice had Salmonella in the tumor tissue. In three months, the tumors were not detected in 11 of the 20 mice. The mice in the control group which did not get the Salmonella
and the FlaB protein succumbed to the disease.
The research team then transplanted metastasized human colon cancer cells into a different mice group. Eight of these were given the FlaB-secreting Salmonella
and six were given non-FlaB type. Seven mice did not receive any kind of treatment. In 27 days, the seven untreated mice and the six mice which got the non-FlaB version had more than a dozen metastases. However the eight mice which got the FlaB-secreting Salmonella developed just four secondary tumors with some showing no sign of metastasis.
From the above experiment and reporting, it is clear that the FlaB protein has anti-cancer, anti-tumor properties. According to a mail by Min and Rhee, FlaB seems to activate a secondary molecule called TLR5 (Toll-like receptor 5) which develop a more aggressive defense in immune cells. The research team currently plan to refine their process through animal models and also run human clinical trials in the next few years.
- Scientiststurn food poisoning microbe into powerful cancer fighter - (http://www.sciencemag.org/news/2017/02/scientists-turn-food-poisoning-microbe-powerful-cancer-fighter)