Somatic Mutations in Oncogenes Are in Chronic Myeloid Leukemia Acquired De Novo via Deregulated Base-Excision Repair and Alternative Non-Homologous End Joining

Abstract

Somatic mutations are a common molecular mechanism through which chronic myeloid leukemia (CML) cells acquire resistance to tyrosine kinase inhibitors (TKIs) therapy. While most of the mutations in the kinase domain of BCR-ABL1 can be successfully managed, the recurrent somatic mutations in other genes may be therapeutically challenging. Despite the major clinical relevance of mutation-associated resistance in CML, the mechanisms underlying mutation acquisition in TKI-treated leukemic cells are not well understood. This work demonstrated de novo acquisition of mutations on isolated single-cell sorted CML clones growing in the presence of imatinib. The acquisition of mutations was associated with the significantly increased expression of the LIG1 and PARP1 genes involved in the error-prone alternative nonhomologous end-joining pathway, leading to genomic instability, and increased expression of the UNG, FEN and POLD3 genes involved in the base-excision repair (long patch) pathway, allowing point mutagenesis. This work showed in vitro and in vivo that de novo acquisition of resistance-associated mutations in oncogenes is the prevalent method of somatic mutation development in CML under TKIs treatment.

Presence of Myeloid Mutations in Patients with Chronic Myeloid Leukemia Increases Risk of Cardiovascular Event on Tyrosine Kinase Inhibitor Treatment

“…We retrospectively analyzed 200 ng of genomic DNA extracted from peripheral blood at diagnosis. Diagnostic samples were selected for sequencing to enable the identification of mutations in CML leukemic cells since TKI treatment can cause the gain or loss of somatic mutations [ 19 , 25 ] and samples taken when patients are in molecular remission typically have undetectable levels of leukemia cells [ 19 , 24 ].…”

Non-homologous End-joining Genotype, mRNA Expression, and DNA Repair Capacity in Childhood Acute Lymphocytic Leukemia

“…The aberrant repair of DSBs can result in significant genomic instability, which is a driving force in carcinogenesis. There is a limited body of literature that has investigated the involvement of the NHEJ repair pathway and its associated genes in the etiology of leukemia (39)(40)(41)(42). Furthermore, as far as we are aware, there have been no reports that have examined the association of NHEJ genotype and NHEJ repair capacity in leukemia, especially childhood ALL.…”

New Inhibitors of Bcr-Abl Based on 2,6,9-Trisubstituted Purine Scaffold Elicit Cytotoxicity in Chronic Myeloid Leukemia-Derived Cell Lines Sensitive and Resistant to TKIs

“…KBM5 cell line was kindly gifted by Vladimír Divoký. Development of KCL22 subclones B8 (T315I, 100%), F4 (E255K, 100%), and B10 (Y253H, 50%) was reported previously [18]. All cell lines were cultivated in humidified incubator at 37 • C and in 5% CO 2 according to the provider's instructions in appropriate media supplemented with 10% fetal bovine serum, penicillin (100 IU/mL), streptomycin (100 µg/mL), and glutamine (4 mM).…”

“…To directly compare the sensitivity of synthesized compounds to the most common Bcr-Abl mutations, they were evaluated on a panel of KCL22 subclones expressing different Bcr-Abl point mutants, including B8 (T315I, 100%), F4 (E255K, 100%), and B10 (Y253H, 50%) [18]. The sensitivity to these compounds was evaluated by cytotoxicity assays, and these results were expressed as GI 50 values (Table 3).…”