For the first time in history, scientists used a CRISPR-Cas9 gene change technique to attack the tumor development center itself. In a study conducted in mice, the new method has been able to prolong survival and stop the growth of a tumor.
According to a paper published in the Nature Biotechnology magazine, a team from the University of Pittsburgh in its research aimed at the so-called “fusion” genes that occur when two genes connect into a single hybrid one. Such genes often create abnormal proteins that cause tumors or help in development of one.
However, fusion genes have a unique gene that allows scientists to find and change them. With the help of a specially designed adenovirus, the team replaced the fusion genes with genes that are in charge of killing tumor cells.
“This is the first time that gene editing has been used to specifically target cancer fusion genes,” said research team leader Jian-Hua Luo.
“It’s really exciting because it lays the foundation for something that could become a completely new approach to cancer treatment,” he added.
How does CRISPR work?
CRISPR-Cas9 allows scientists to cut out a certain part of a defective gene at a precisely defined spot in the DNA, and possibly replace it with other, correct or useful ones.
CRISPR is, in fact, a natural mechanism that many bacteria use to defend against viruses. Scientists in the 1980s noted that some parts of the DNA of bacteria constantly repeated in an unusual way, and that between them, commonly, there are some unique interspaced DNA parts.
This unusual configuration is called “clustered regularly interspaced short palindromic repeats”, or CRISPR. Research has shown that CRISPR contains segments of the gene code of hostile viruses that the bacteria previously encountered and that it is an important part of the bacteria defense system. Based on this code, the bacterium recognizes the intruder and launches an effective attack against it.
Enzymes Cas (CRISPR-associated proteins) represent the second part of this system. The bacterium will copy these parts of the hostile virus into relatively short RNA messages and associate them with the corresponding enzyme Cas. Such weapons will multiply and patrol the bacteria.
When it encounters the identical code in the nucleic acid of the virus, Cas will immediately cut it in a recognized place to prevent its duplication.
The described functionality of the CRISPR-Cas9 composition makes it possible to create an RNA sequence that will, together with Cas9, accurately match the sequence of the base that encodes the problematic gene in the DNA, which we want to cut or change. In this way, scientists can create a CRISPR-Cas9 that will cut and erase harmful mutated and non-functional genes, and even insert the correct ones into the cell.