Determination of Exosome Mitochondrial DNA as a Biomarker of Renal Cancer Aggressiveness

Abstract Background: Components of liquid biopsy are promising non-invasive biomarkers for monitoring the renal cell carcinoma (RCC) status. Present study tries to evaluate the role of exosomes and mitochondrial DNA (mtDNA) as promise, novel and stable biomarkers that could improve current ones in RCC. Methods: A total of 140 fractions obtained by ultracentrifugations of whole blood samples stored in EDTA anticoagulant from 28 (13 patients and 15 controls) were included in present study. An exosome collection protocol and exhaustive analysis of all phases obtained by ultracentrifugations (named from B to F) was performed. Subsequently, an analysis of dPCR (digital PCR) using the QuantStudio™ 3D Digital PCR platform and the quantification of mtDNA copy number using by QuantStudioTM 12K Flex Real-Time PCR System (qPCR) was developed. Moreover, Next Generation Sequencing (NGS) analyses were included using MiSeq system (Illumina, CA, USA). Results: F fraction, which contains all exosomes´ data and all mitochondrial markers (hypervariable region 1 (HV1) and apocytochrome b of complex III (MT-CYB)) were statistically identified in dPCR and qPCR (p values < 0.05) when a comparison between cases and controls was performed. Moreover, the studied mitochondrial genes shown a relevant significance in RCC aggressiveness analyses (metastasis and stages 4).Conclusions: To sum up, this is the first time a relation between mtDNA genetic markers in exosome and clinical management of RCC is suggested.