Abstract
Astrocytomas are common malignant intracranial tumors that comprise the majority of adult primary central nervous system tumors. MicroRNAs (miRNAs) are small, non-coding RNAs (20–24 nucleotides) that post-transcriptionally modulate gene expression by negatively regulating the stability or translational efficiency of their target mRNAs. In our previous studies, we found that the downregulation of miR-106a-5p in astrocytomas is associated with poor prognosis. However, its specific gene target(s) and underlying functional mechanism(s) in astrocytomas remain unclear. In this study, we used mRNA microarray experiments to measure global mRNA expression in the presence of increased or decreased miR-106a-5p levels. We then performed bioinformatics analysis based on multiple target prediction algorithms to obtain candidate target genes that were further validated by computational predictions, western blot analysis, quantitative real-time PCR, and the luciferase reporter assay. Fas-activated serine/threonine kinase (FASTK) was identified as a direct target of miR-106a-5p. In human astrocytomas, miR-106a-5p is downregulated and negatively associated with clinical staging, whereas FASTK is upregulated and positively associated with advanced clinical stages, at both the protein and mRNA levels. Furthermore, Kaplan-Meier analysis revealed that the reduced expression of miR-106a-5p or the increased expression of FASTK is significantly associated with poor survival outcome. These results further supported the finding that FASTK is a direct target gene of miR-106a-5p. Next, we explored the function of miR-106a-5p and FASTK during astrocytoma progression. Through gain-of-function and loss-of-function studies, we demonstrated that miR-106a-5p can significantly inhibit cell proliferation and migration and can promote cell apoptosis in vitro. The knockdown of FASTK induced similar effects on astrocytoma cells as those induced by the overexpression of miR-106a-5p. These observations suggest that miR-106a-5p functions as a tumor suppressor during the development of astrocytomas by targeting FASTK.
Highlights
Astrocytomas are the most common primary brain tumors in the central nervous system [1]
Using Kaplan-Meier survival analysis, we showed that the low expression of miR-106a-5p or the increased expression of Fas-activated serine/threonine kinase (FASTK) is significantly associated with poor survival outcome in astrocytoma patients
A set of 36 genes was identified as candidate miR-106a-5p targets (Figure 1C and Table 1) In order to validate the specificity of pre-miR-106a-5p and anti-miR-106a5p and their off target effects, we transfected U251 cells with equal amounts of pre-ncRNA, pre-miR-106a-5p, anti-ncRNA or antimiR-106a-5p, and the expression level of miR-106b, another member of the miR-106 family whose sequence is most similar to miR-106a-5p, was assessed by quantitative RT-PCR assay
Summary
Astrocytomas are the most common primary brain tumors in the central nervous system [1]. Increasing numbers of genetic and molecular aberrations, which are the causes and consequences of deregulated intracellular signaling networks, have been correlated with the development of astrocytomas. These alterations have not been fully elucidated. The reduced expression of miR-106a5p is associated with poor survival outcome, suggesting that miR106a-5p elicits a tumor suppressive role during astrocytoma development and/or progression [8]. MiR-106a-5p belongs to the miR-17 family, which includes miR-17-5p, miR-20a, miR-20b, miR-106a-5p, miR-106b and miR-93. The miR-17 family is divided into three clusters according to consensus seed regions, and miR-106a-5p is a member of the miR-106a-363 cluster, which
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
