Gene Editing Effects of CRISPR/Cas on Breakpoint Cluster Region Gene Targets Using White-to-Blue Colony Formation Assay

Abstract

Leukemia with Philadelphia chromosome positive is the most severe type in children with an extremely short average survival period. The lack of effective drugs to this type of leukemia prompted the development of alternative therapies including gene therapy. Breakpoint cluster region (BCR) chimeras are the major cancer driving mutations. In the present study, several targets of the BCR were tested for their susceptibilities to be edited by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) protein 9 system (CRISPR/Cas9). With a newly developed white-to-blue colony formation assay, the highly variable gene editing effects of CRISPR/Cas on BCR gene targets had been observed. The targets with relatively higher target effects may have clinical impact in gene therapy. This study also demonstrated the usefulness of the simple and very efficient screening assay in future gene therapy studies and clinical practice.