Regulation of miR-126 and miR-122 Expression and Response of Imatinib Treatment on Its Expression in Chronic Myeloid Leukemia Patients.

Background: MicroRNAs (miRNAs) have been observed to exhibit altered expression patterns in chronic myeloid leukemia (CML). Therefore, this study was aimed to evaluate the clinical importance of miR-126 and miR-122 expression in concert to imatinib response in CML patients.

Methods: The present study included 100 CML and 100 healthy subjects. The expression of the 2 miRNAs was performed using TaqMan probe chemistry, and snU6 was used as internal control.

Results: The expression of miR-126 and miR-122 was downregulated in CML patients, with a mean fold change ± SD 0.20 ± 0.33 and 0.22 ± 0.37, respectively. While the expression of both miRNAs was analysed before and after imatinib treatment, it was observed that the expression levels of both were increased after imatinib treatment by 26.25-fold (5.33 against 0.20) and 13.95-fold (3.07 against 0.22) and the increase was statistically significant (p < 0.0001 and p < 0.0001, respectively). The expression of miR-126 was not conclusive when compared in different clinical stages of the CML disease as it showed a decreased expression in patients with accelerated phase compared to chronic phase (mean fold change = 0.03 and 0.27, respectively), but patients with chronic phase and blastic phase had comparable expression (mean fold change = 0.27 and 0.24, respectively). We also observed an increased expression of both miRNAs after imatinib therapy in each clinical phase.

Conclusion: The study concludes that expression of miR-126 and miR-122 increases after imatinib treatment in CML patients and that miR-126 defines the good responders of imatinib therapy.