miRNAs as Biomarkers in Chronic Myelogenous Leukemia.

Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm that is frequently characterized by the constitutive expression of the oncogenic protein BCR-ABL tyrosine kinase. Tyrosine kinase inhibitors (TKIs) targeting breakpoint cluster region-ABL are the first-line therapy for most CML patients and have drastically improved the prognosis of CML. However, some CML patients are unresponsive to TKI treatment, and a notable proportion of initially responsive patients develop drug resistance. Several molecular pathways have been correlated with resistance to TKI treatment, however, the exact mechanism of developing drug resistance remains ambiguous. Recently, microRNAs (miRNAs) have been implicated in the progression of CML and the development of resistance to TKI treatment based on their important regulatory function in cell homeostasis, and the deregulation observed in the initiation and progression of many leukemia subtypes. In this review, we summarize some of the major discoveries regarding miRNAs in CML, and their relevance as biomarkers for diagnosis, disease progression, and drug sensitivity.