Genetically modified bacteria can act as biosensors and detect cancer in the body. Researchers discovered this in connection with colon cancer in experiments on cell cultures and mice. The method is still a long way from clinical use, they say.
The method is based on the so-called horizontal gene transfer, which is widespread in bacteria. The pathogens not only receive genetic material as part of their reproduction, but also take up DNA sequences from their immediate environment. This is important because tumors release bits of genetic material into their environment.
For their study, a research team led by Susan Woods of the University of Adelaide and Jeff Hasty of the University of California San Diego used a bacteria called Acinetobacter baylyi, which is known for its ability to absorb genetic material from the outside.
Bacteria modified with gene scissors
Using CRISPR/Cas gene scissors, the scientists engineered the bacteria to respond to circulating DNA that contains a mutation in a cancer gene called KRAS (an acronym for Kirsten Rat Sarcoma). These KRAS variants are often involved in the onset of colon cancer and many other tumors.
“When we started the project four years ago, it was not even certain that it was even possible to use bacteria as a sensor for mammalian DNA,” Hasty said in a statement from his university. The procedure called CATCH (Cellular Assay for Targeted Crispr-discriminated Horizontal gene transfer) aims to ensure that bacteria take up such DNA directly on site and compare it with sequences of certain cancer genes.
Colorectal cancer reliably detected in mice
If the bacteria don’t encounter the KRASG12D cancer gene, an antibiotic they make will kill them. However, if the gene is present, a resistance mechanism is activated and the microorganisms can multiply. According to the researchers, the sensor bacteria reliably detected the intestinal tumors in tests on mice.
However, CATCH technology is currently still limited to certain sequences, so “cancer detection is limited to hotspot mutations such as KRASG12D,” the researchers write in the journal Science. In the future, such organisms could not only find other diseases besides cancer, but also treat them at the same time, the scientists predict.
Ultimately, it is even conceivable to equip the bacterial biosensors with substances such as peptides, small molecules or nanobodies, reports the team led by Woods and Hasty. Then they can immediately release the correct active substances when a disease is detected.
Source: Krone
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