Circulating MicroRNAs in Plasma as Novel Biomarkers for Alzheimer's Disease

Abstract

Alzheimer’s disease (AD) is the most common and complex neurodegenerative disorder. Although it has been over a hundred years since AD was originally described, the exact underlying mechanism remains largely elusive and no curative drugs are available for AD treatment. Early diagnosis of AD is believed to be essential for effective administration of drugs targeting. However, there are still no prefect biomarkers for AD diagnosis. Recent findings suggest that microRNAs (miRNAs) in the circulating system act as potential biomarkers for AD. In the present study, we extracted total RNAs from the plasma of 12 Chinese AD patients and 6 normal controls. Eight miRNA candidates (miR-29a, -125b, -146b, let-7f, -181a, -30c, -128 and -16) were selected and their expression profiles in plasma were measured using qRT-PCR (quantitative reverse transcription polymerase chain reaction). Our data demonstrated that plasma miR-128 was significantly down-regulated in AD patients compared with control subjects. Moreover, plasma miR-128 levels significantly correlated with protein markers in cerebrospinal fluid (CSF) and Mini Mental State Examination (MMSE) scores of the subjects. Importantly, plasma miR-128 showed good accuracy to distinguish AD patients from control subjects based on receiver operating characteristic (ROC) curve analysis. In conclusion, our results indicated that miR-128 in plasma could be a potential non-invasive biomarker of AD.