Engineered Bacteria Could One Day Save Your Life From Cancer

The earlier you detect the presence of cancer, the better your chances are that treatments will work to completely eradicate it. That’s why researchers are constantly looking for better ways to make early detection of tumors possible. According to a new paper published in Science on Thursday, now there’s one more tool to add to this arsenal: genetically engineered bacteria.

That’s probably not the most comforting string of words to put together, but it could be a gamechanger. Called CATCH (short for “Cellular Assay for Targeted CRISPR-discriminated Horizontal gene transfer”), the new tool could be a game changer in identifying DNA sequences and mutations associated with intestinal cancers.

“As we started on this project four years ago, we weren’t even sure if using bacteria as a sensor for mammalian DNA was even possible,” Jeff Hasty, a researcher at the University of California, San Diego who led the new study, said in a statement. “The detection of gastrointestinal cancers and precancerous lesions is an attractive clinical opportunity to apply this invention.”

CATCH doesn’t work like a simple detector that flags the presence of cancer. It takes advantage of the fact that tumors shed their own DNA into the surrounding environment. If it were possible to detect these free-floating DNA, that could be used as a proxy signal for alerting us to the presence of a tumor.

It just so happens that many types of bacteria are able to absorb DNA from their surroundings. CATCH is basically a method that deploys bacteria specifically designed to look for cancerous DNA and absorb it—working as a living biosensor for tumors. Hasty and his team were especially interested in seeing if CATCH could play a role in detecting colorectal cancer, the third leading cause of cancer-related death in the U.S..

The bacteria the team decided to use was Acinetobacter baylyi, which they believed would fulfill the need for a bacteria species that could take up external DNA and be tinkered with CRISPR in order to analyze its contents.

Josephine Wright

The team developed and tested out their new CATCH system using an engineered version of Acinetobacter baylyi that could look for KRAS, a gene that mutates in many different types of cancers. The species was designed to only pick up mutated forms of KRAS that are common in precancerous polyps and tumors. They then tested CATCH out on mice that had colorectal cancer, and found that the engineered Acinetobacter baylyi acted as an effective biosensor for detecting the presence of tumors.

The next step in this line of work would be not simply to use bacteria to detect cancer, but to engineer that bacteria to then treat the cancer as well. “There is so much potential to engineer bacteria to prevent colorectal cancer, a tumor that is immersed in a stream of bacteria, that could help, or hinder, its progression,” study co-author Susan Woods from the University of Adelaide in Australia said in a statement.

A lot more work will be necessary to prove out this kind of application, let alone validate the use of this bacteria as a cancer biosensor. But the new study opens the door for a new way of intervening against tumors without the need for invasive biopsies or harsh chemotherapy and radiation.