Scientists at the University of Waterloo have made significant strides in cancer treatment by engineering bacteria that can consume tumors from the inside. This innovative approach utilizes Clostridium sporogenes, a bacterium typically found in soil that thrives in oxygen-free environments. Researchers have discovered that these bacteria can multiply within solid tumors, effectively targeting and degrading cancerous cells.
The research, recently published in the journal ACS Synthetic Biology, highlights a potential breakthrough in cancer therapy. Solid tumors often contain dead cells and lack oxygen, creating an ideal environment for C. sporogenes to flourish. Professor Marc Aucoin, a chemical engineer involved in the study, explained, “Bacteria spores enter the tumor, finding an environment where there are lots of nutrients and no oxygen… So, we are now colonizing that central space, and the bacterium is essentially ridding the body of the tumor.”
This method could provide a viable alternative to traditional cancer treatments such as chemotherapy and radiation therapy, which often come with severe side effects. The ability of bacteria to stimulate an immune response against tumors further underscores their potential utility in cancer therapy. According to Christopher Johnston, a genomic medicine researcher at the University of Texas, “Using ‘bugs as drugs’ offers a promising solution to overcome some of the challenges with traditional cancer therapies.”
In related studies, engineered strains of E. coli and Salmonella have also demonstrated the ability to shrink tumors in laboratory mice. While this research marks substantial progress, the team at Waterloo faced significant challenges. One major hurdle was ensuring that the C. sporogenes bacteria could survive the oxygen-rich environment at the edges of tumors. To address this, researchers genetically modified the bacteria to tolerate some oxygen levels, as detailed in a 2023 study.
Employing a technique known as “quorum sensing,” the researchers ensured that the oxygen-resistant gene was activated only after the bacteria had sufficiently multiplied within the tumor. This modification allows the bacteria to thrive long enough to effectively destroy the tumor. The team also engineered the bacteria to produce a green fluorescent protein, which acts as a visual indicator of their activity within the tumor.
Brian Ingalls, a professor of applied mathematics at Waterloo, described their approach: “Using synthetic biology, we built something like an electrical circuit, but instead of wires we used pieces of DNA. Each piece has its job. When assembled correctly, they form a system that works in a predictable way.”
Currently, the research is at the proof-of-concept stage, with comprehensive testing in human subjects still in the early phases. The Waterloo team aims to integrate their findings on genetic modification and quorum sensing into a single strain of bacteria for pre-clinical trials, marking a crucial step toward potential human applications.
As the scientific community continues to explore the therapeutic potential of engineered bacteria, this innovative approach could redefine cancer treatment and offer new hope for patients facing this challenging disease.
