Researchers from the University of California, Irvine, have developed a DNA enzyme — or DNAzyme — that can differentiate between two strands of RNA inside a cell and cut the strand associated with disease while leaving the healthy strand intact. An advanced ‘gene silencing’ technique could revolutionize the development of DNA enzymes for the treatment of cancer, infectious diseases and neurological disorders.
Enzymes are DNA enzymes that cut other molecules. Through chemistry, the UCI team developed the Dz 46 enzyme, which specifically targets the RNA mutation of an allele in the KRAS gene, a master regulator of cell growth and division, found in 25 percent of all human cancers. A description of how the team achieved the development of this enzyme was recently published in the online journal Nature Communications.
“Producing enzymes that can function effectively in normal conditions of cell systems has been more challenging than expected,” said corresponding author John Chaput, UCLA professor of pharmaceutical sciences. “Our results indicate that chemotherapy could pave the way for the development of new therapies for a wide range of diseases.”
Gene silencing has been available for more than 20 years and some of the FDA-approved drugs have different versions of the technology, but none can characterize a single point mutation in the RNA strand. The benefit of the Dz 46 enzyme is its ability to identify and cut a specific genetic mutation, providing patients with innovative and accurate medical treatment.
DNAzyme looks like the Greek letter omega and acts as a catalyst by speeding up chemical reactions. The “arms” on the left and right are attached to the target region of the RNA. The loop binds to the magnesium and bends and cuts the RNA at a very specific site. But producing enzymes with strong multicyclic activity under physiological conditions requires some ingenuity, because enzymes are highly dependent on magnesium concentrations not found within a human cell.
“We solved this problem by re-engineering the DNA using chemistry to reduce its dependence on magnesium and we did it in a way that we could maintain high catalytic turnover activity,” said Chabot. “Our model is one of the first examples, if not the first, of achieving this. The next steps are to get Dz 46 to a point where it is ready for preclinical trials.”
Also participating in this study were team members Kim Thien Nguyen, project scientist, and Turnee N. Malik, postdoctoral researcher, both from the Department of Pharmaceutical Sciences.
The researchers and UCI have filed provisional patent applications on the chemical structure and cleavage preference of Dz 46. Chaput is a consultant for drug development company 1E Therapeutics, which supported this work.