MicroRNA Composition of Plasma Extracellular Vesicles: A Harbinger of Late Cardiotoxicity of Doxorubicin

Background : The use of doxorubicin is associated with an increased risk of acute and long-term cardiomyopathy. Despite the constantly growing number of cancer survivors, little is known about the transcriptional mechanisms which progress in the time leading to a severe cardiac outcome. It is also unclear whether long-term transcriptomic alterations related to doxorubicin use are similar to transcriptomic patterns present in patients suffering from other cardiomyopathies. Methods: We have sequenced miRNA from total plasma and extracellular vesicles (EVs) from 66 acute lymphoblastic leukemia (ALL) survivors and 61 healthy controls (254 samples in total). We analyzed processes regulated by differentially expressed circulating miRNAs and cross-validated results with the data of patients with clinically manifested cardiomyopathies. Results: We found that especially miRNAs contained within EVs may be particularly informative in terms of cardiomyopathy development and may regulate pathways related to neurotrophin, transforming growth factor beta or epidermal growth factor receptors ( ErbB). We identified vesicular miR-144-3p and miR-423-3p as the most variable between groups and significantly correlated with echocardiographic parameters and for plasma: let-7g-5p, miR-16-2-3p. Vesicular miR-144-3p correlates with the highest number of echocardiographic parameters and is differentially expressed in the circulation of patients with dilated cardiomyopathy. We also found that distribution of particular miRNAs between of plasma and EVs (proportion between compartments) e.g., miR-184 in ALL is altered suggesting alterations in secretory and miRNA sorting mechanisms. Conclusions: Our results show that transcriptomic alterations which lead to cardiomyopathy development many years after doxorubicin treatment are reflected in circulating miRNA levels. Among miRNAs related to cardiac function we found vesicular miR-144-3p and miR-423-3p and let-7g-5p, miR-16-2-3p contained in total plasma. Selection of source for such studies (plasma or EVs) is of critical importance as distribution of some miRNA between plasma and EVs is altered in ALL survivors in comparison to healthy people which suggests that doxorubicin-induced changes include miRNA sorting and export to extracellular space.