Imatinib-induced changes in expression profile of microRNA in plasma of mice - comparison with doxorubicin

Cardiotoxicity is serious adverse reaction of cancer chemotherapy and may lead to critical heart damage. Imatinib mesylate (IMB), a selective tyrosine kinase inhibitor, is sometimes accompanied by severe cardiovascular complications. To minimize the risk, early biomarkers of such complications are of utmost importance. MicroRNAs (miRNAs) are, nowadays intensively studied as potential biomarkers of many pathological processes. Many miRNAs appear to be specific in some tissues, including heart. Here, we have explored the potential of specific miRNAs to be early markers of IMB-induced cardiotoxicity. Doxorubicin (DOX), an anthracycline with well-known cardiotoxicity, was used for comparison. NMRI mice were treated with IMB or DOX for nine days in doses corresponding to the highest recommended doses in oncological patients. Then, plasmatic levels of miRNAs were analyzed by miRNA microarrays and selected cardio-specific miRNAs were quantified using qPCR. The plasmatic level of miR-1a, miR-133a, miR-133b, miR-339, miR-7058, miR-6236 and miR-6240 were the most different between IMB-treated and control mice. Interestingly, most of the miRNAs affected by DOX were also affected by IMB with the same trends. Concerning selected microRNAs in hearts of individual mice, only miR-34a was significantly increased after DOX treatment and only miR-205 was significantly decreased after IMB and DOX treatment. However, changes in any miRNA expression did not correlate with level of troponin T, classical marker of heart injury. Mice were randomly divided in three groups. The animals in the first group (n=9) were treated p.o. with IMB (distilled water solution) in daily dose 100 mg/kg of body weight for 9 consecutive days. The animals in the second group (n=9) were treated i.v. (tail vein) with DOX in saline solution (one dose 3mg/kg, 4 doses, application every other day). The mice in control group (n=6) were treated with the solvents only. The next day after the last dose of drugs, mice were sacrificed by cervical spine dislocation. Blood from aorta was collected into K2EDTA-coated tubes and centrifuged to get plasma samples. Total RNA was isolated from 300 μl of plasma (pooled sample of 3 treated mice as a biological replicate) by miRNeasy Serum/Plasma Kit (Qiagen) according to manufactures’ protocol.