Assessment of salivary microRNA by RT-qPCR: Challenges in data interpretation for clinical diagnosis

Abstract

Human saliva has attracted a great attention to the medical diagnostic field as a potential biofluid that provides access to various types of biomarkers in a non-invasive manner. In particular, the recent focus has been on microRNA (miRNA) due to their extracellular circulation for cell-cell communication and their dysregulation has been associated to diverse diseases. However, their analysis by the golden standard (RT-qPCR) are highly heterogenous, where miRNA signatures differ depending on the study and on the method of normalization. Using 6 miRNA targets and 10 participants through a 3 months study, here we show that a RT-qPCR kit is capable of demonstrating significant differences, yet they have inssuficient comparable rigour since the majority do not fall within the quantification region. In addition, we observed high crosstalk between the miRNA assays, altogether demonstrating that the patterns and differences observed are most likely associated to technical limitations rather than to biological contexts. As a result, we believe that more rigorous data analysis should be done prior extrapolating conclusions, which will help to homogenize results for the relay to molecular diagnostics.