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MicroRNAs (miRNAs) are short non-coding RNA molecules that regulate gene expression through post-transcriptional repression of target genes. They have been shown to be implicated in the pathophysiology of Alzheimer's disease (AD) and proposed as disease biomarkers. In the present work, we have studied the expression levels of 754 miRNAs in cerebrospinal fluid (CSF) from AD patients and control subjects. We have explored a first screening cohort ( N = 20) and selected 12 miRNAs to be further tested in a second independent validation cohort ( N = 69). We have found a significant upregulation of miR-222 and miR-125b in AD CSF. Of these, the association of miR-222 with AD is novel and reported here for the first time whereas upregulation of miR-125b has been previously reported in AD brain. Yet we do not find association with other miRNAs which were previously linked to AD. Our results shed light on potential underlying pathophysiological processes of AD and also point out the need for consensus procedures in CSF miRNA detection and data analysis. [ABSTRACT FROM AUTHOR]

Glioma is the most prevalent primary brain tumors in adults. In addition to the high incidence and mortality rate, the 5-year survival rate of glioma is also extremely low. MicroRNAs (miRNAs), as a class of small non-coding RNAs, may play an important role in carcinogenesis. It was also proposed that miRNAs might also be associated with glioma diagnosis and prognosis. In this study, we aimed at investigating the predictive and prognostic values of miR-125b, miR-221, and miR-222 in glioma and, hopefully, to provide some evidence for novel therapy of glioma. Tissue specimens were obtained from tumor tissue and adjacent non-tumor tissue. RNA was extracted and qRT-PCR was performed with U6 being the internal control. Receiver-operating characteristic (ROC) curves were constructed, and the area under the ROC curves (AUC) was calculated to evaluate the significance of candidate miRNAs in distinguishing glioma tumor tissues and adjacent normal tissues. Survival curves of Kaplan-Meier method were constructed for both high expression group and low expression group, and the difference between curves was evaluated by log-rank test. All the statistical analyses were performed using Stata version 12.0 software, and graphs were generated by GraphPad Prism 5.0. The significance of miR-125b, miR-221, and miR-222 expression level in distinguishing glioma tumor from adjacent non-tumor tissues was further validated. Combination of miR-125b, miR-221, and miR-22 was significantly superior compared to the clinical standard of using these miRNAs alone. A clear demarcation was shown by survival analysis between patients with high miR-125b, miR-221, and miR-222 expression and patients with poor prognosis. Similarly, panel of these miRNAs could play a better prognostic role in glioma. In this study, we confirmed the significance of miR-125b, miR-221, and miR-222 in distinguishing glioma tumor from adjacent non-tumor tissues. Higher expressions of miR-125b and miR-222 have also been proved to be associated with glioma. Furthermore, glioma patients with higher miR-125b, miR-221, and miR-222 expression were manifested to have poorer prognostic status, which might be attributed to their attenuated sensitivity to chemotherapy and radiotherapy. [ABSTRACT FROM AUTHOR]