Engineered Bacteria Shown to Consume Tumors in New Cancer Treatment | University of Waterloo Research

The fight against cancer may be entering a new era, one where microscopic allies are deployed to dismantle tumors from within. Researchers at the University of Waterloo are pioneering a novel approach: engineering bacteria to actively consume cancerous growths. This isn’t about boosting the immune system to *recognize* cancer, but about using microbes to directly *eradicate* it, a strategy that holds particular promise for solid tumors where traditional treatments struggle to penetrate.

Targeting the Oxygen-Deprived Core

The core principle behind this innovative treatment lies in exploiting the unique environment within tumors. Solid tumors often develop areas with extremely low oxygen levels – a condition known as hypoxia. Even as inhospitable to most cells, this oxygen-deprived environment is ideal for certain types of bacteria, specifically Clostridium sporogenes, a common soil bacterium. “Bacteria spores enter the tumor, finding an environment where there are lots of nutrients and no oxygen, which this organism prefers and so it starts eating those nutrients and growing in size,” explains Dr. Marc Aucoin, a chemical engineering professor at Waterloo. “So, we are now colonizing that central space, and the bacterium is essentially ridding the body of the tumor.”

This isn’t the first time bacteria have been explored as a cancer treatment. Bacterial therapies have been investigated for decades, but a key challenge has been controlling their behavior and ensuring they target cancer cells specifically. The Waterloo team’s breakthrough lies in genetically modifying Clostridium sporogenes to enhance its tumor-targeting capabilities and, crucially, to regulate its activity.

Overcoming Bacterial Limitations

While C. Sporogenes thrives in the oxygen-free core of tumors, it struggles to survive in areas with even small amounts of oxygen, like the edges of the tumor or the bloodstream. To address this, researchers introduced a gene from a related bacterium that confers greater oxygen tolerance. However, simply making the bacteria oxygen-resistant wasn’t enough. Activating this tolerance too early could allow the bacteria to proliferate in unintended areas, posing a safety risk.

The team cleverly solved this problem using a natural bacterial communication system called quorum sensing. Quorum sensing relies on bacteria releasing chemical signals. As the bacterial population grows, the concentration of these signals increases. The researchers engineered the bacteria to only activate the oxygen-tolerance gene when the signal reaches a critical threshold – meaning only when a sufficient number of bacteria have colonized the tumor. This ensures the bacteria remain contained within the tumor environment until they’ve established a strong foothold. You can learn more about quorum sensing and its applications in microbiology on ScienceDaily.

Synthetic Biology and DNA Circuits

The engineering of these bacteria isn’t a simple process. It relies on the principles of synthetic biology, where biological systems are designed and constructed to perform specific functions. Dr. Brian Ingalls, a professor of applied mathematics at Waterloo, describes the process as building “an electrical circuit, but instead of wires we used pieces of DNA.” Each DNA component has a defined role, and when assembled correctly, the system functions predictably. In a previous study, the team demonstrated that Clostridium sporogenes could be genetically altered to withstand oxygen. They then validated their quorum sensing design by programming the bacteria to produce a green fluorescent protein, confirming that the system activated at the intended bacterial density.

A Collaborative Effort

This research is a testament to interdisciplinary collaboration. It began with the work of PhD student Bahram Zargar, supervised by Dr. Ingalls and Dr. Pu Chen. The project brings together expertise in engineering, mathematics, and life sciences, reflecting the University of Waterloo’s commitment to translating scientific discoveries into practical medical solutions. The team is also collaborating with the Center for Research on Environmental Microbiology (CREM Co Labs) in Toronto, and includes Dr. Sara Sadr, a former Waterloo doctoral student. This collaborative approach is crucial for tackling the complexities of cancer treatment.

What’s Next for This Bacterial Therapy?

The next step involves combining the oxygen-tolerance gene and the quorum-sensing control system into a single bacterium and evaluating its effectiveness in pre-clinical trials. These trials will likely involve laboratory studies and animal models to assess the safety and efficacy of the engineered bacteria. While promising, it’s important to remember that this research is still in its early stages. A clinical trial involving human patients is estimated to be three to four years away, with potential treatment availability in approximately five years, contingent on continued funding and successful trial outcomes. The University of Waterloo provides further details on their research on their news website.

The development of this bacterial cancer therapy represents a significant step forward in the search for innovative treatment options. By harnessing the power of microbes, researchers are exploring a fundamentally different approach to fighting cancer – one that could offer new hope for patients facing challenging diagnoses. Further research and rigorous testing will be essential to determine the full potential of this groundbreaking technology. For more information on cancer research and treatment options, consult with a qualified healthcare professional and refer to resources from organizations like the National Cancer Institute.