ABLGenomic Editing Sufficiently Abolishes Oncogenesis of Human Chronic Myeloid Leukemia Cells In Vitro and In Vivo

Chronic myelogenous leukemia (CML) is the most common type of leukemia in adults, and more than 90% of CML patients harbor the abnormal Philadelphia chromosome (Ph) that encodes the BCR-ABL oncoprotein. Although the ABL kinase inhibitor (imatinib) has proven to be very effective in achieving high remission rates and improving prognosis, up to 33% of CML patients still cannot achieve an optimal response. Here, we used CRISPR/Cas9 to specifically target theBCR-ABLjunction region in K562 cells, resulting in the inhibition of cancer cell growth and oncogenesis. Due to the variety ofBCR-ABLjunctions in CML patients, we utilized gene editing of the humanABLgene for clinical applications. Using theABLgene-edited virus in K562 cells, we detected 41.2% indels inABLsgRNA_2-infected cells. TheABL-edited cells reveled significant suppression of BCR-ABL protein expression and downstream signals, inhibiting cell growth and increasing cell apoptosis. Next, we introduced theABLgene-edited virus into a systemic K562 leukemia xenograft mouse model, and bioluminescence imaging of the mice showed a significant reduction in the leukemia cell population inABL-targeted mice, compared to the scramble sgRNA virus-injected mice. In CML cells from clinical samples, infection with theABLgene-edited virus resulted in more than 30.9% indels and significant cancer cell death. Notably, no off-target effects or bone marrow cell suppression was found using theABLgene-edited virus, ensuring both user safety and treatment efficacy. This study demonstrated the critical role of theABLgene in maintaining CML cell survival and tumorigenicity in vitro and in vivo.ABLgene editing-based therapy might provide a potential strategy for imatinib-insensitive or resistant CML patients.