Abstract: Background – Canine visceral hemangiosarcoma (HSA) has a poor prognosis, is often diagnosed at an advanced stage, and lacks non-invasive definitive diagnostic methods. MicroRNAs (miRNAs) play a critical role in regulating gene expression and are known to be aberrantly expressed in several cancers; they are highly stable and conserved across species, making them appealing for biomarker studies. Our group previously identified 67 differentially expressed (DE) miRNAs in splenic HSA (≥2 fold-change; FDR< 0.01). Hypothesis/Objectives – We propose that DE miRNAs in HSA are organ-specific. To address this hypothesis, we aim to evaluate the DE miRNAs in cardiac HSA and compare them to those previously described in splenic HSA. Animals – The study comprised archived tissue samples from six dogs with cardiac HSA, six control cardiac samples, 18 splenic HSA, and six control spleens. Methods – From formalin-fixed, paraffin-embedded tissues, total RNA was extracted, measured by fluorometry, and sequenced through small RNA sequencing (sRNA-Seq). Results – sRNA-Seq revealed 71 miRNAs DE in cardiac tissue from HSA patients with ≥2 fold-change and FDR < 0.01; 53 of these miRNAs were exclusively DE in the heart, supporting the claim that miRNA expression is organ-specific in dogs with HSA. Conclusions and clinical importance – These distinctive miRNA expression patterns may be useful as biomarkers for diagnosing and determining the site of visceral HSA in dogs. Validation in larger cohorts and blood and effusion samples will contribute to a more comprehensive understanding of the potential of miRNAs as a non-invasive diagnostic tool for visceral HSA.
