By: Gowri Sunil

News Editor

Recently, scientists discovered a new potential cancer treatment involving engineered bacteria. The research process began with PhD student Bahram Zargar at the University of Waterloo in Canada. Zargar worked under Dr. Pu Chen, a retired chemical engineering professor at the university. 

The new treatment features genetically modified bacteria called Clostridium sporogenes, which are usually found in soil, water, and sediments. These bacteria are ideal for tumors since they grow well in oxygen-free environments, fitting the conditions of a tumor, which is filled with rapidly multiplying cells. The scientists discovered that by injecting this bacterium into a person’s body, the bacterium migrates to the tumor and essentially eats it from the inside out. Once inside, the bacteria live in their ideal non-oxygenated, high-nutrient environment. Subsequently, it consumes a lot of the nutrients, causing it to grow much larger and multiply within the tumor. Since this method of cancer therapy targets the actual tumors alone, it could reduce the harm to healthy tissue, an ongoing problem with current treatments like chemotherapy.

However, researchers faced several obstacles while developing a treatment utilizing this bacterial technique. One major challenge scientists faced was keeping the bacteria inside the core of the tumor and away from its outer edges. As the bacteria spread within the tumor, they eventually reach the edges, which contain oxygen. Since the bacteria cannot tolerate oxygen at all, it quickly dies off when exposed. 

To prevent this, scientists plan to insert a gene from the same bacteria that can withstand oxygen longer, allowing the bacteria to prolong its survival as they spread to the edges of tumors. Yet, using this gene introduces another problem in controlling when the tolerance can be activated. If the gene is switched on too early, it risks depleting an individual’s oxygen-rich areas, such as the bloodstream, which is very dangerous. To avoid this, scientists have turned to Quorum sensing. Quorum sensing is a process that relies on chemical signals emitted by bacteria and increases as their population grows. When the bacteria accumulate to high concentrations, the signal becomes strong enough to activate the oxygen-tolerance gene. As Dr. Brian Ingalls, an applied mathematics professor at Waterloo, explained, “Using synthetic biology, we built something like an electrical circuit, but instead of wires we used pieces of DNA.” He added, “Each piece has its job. When assembled correctly, they form a system that works in a predictable way.”

Regarding next steps in the process, the team hopes to combine the tolerance gene with the Clostridium sporogenes. After completing this, they can move on to treating cancerous tumors in preclinical trials. If successful, this technique offers a promising approach to cancer therapy that targets tumors while protecting healthy tissue in an individual.   

(Sources: ScienceDaily, Phys Org, National Institute of Health)