The N 6 -methyladenosine (m 6 A) modification influences various mRNA metabolic events and tumorigenesis, however, its functions in nonsense-mediated mRNA decay (NMD) and whether NMD detects induced carcinogenesis pathways remain undefined. Here, we showed that the m 6 A methyltransferase METTL3 sustained its oncogenic role by modulating NMD of splicing factors and alternative splicing isoform switches in glioblastoma (GBM). Methylated RNA immunoprecipitation-seq (MeRIP-seq) analyses showed that m 6 A modification peaks were enriched at metabolic pathwayrelated transcripts in glioma stem cells (GSC) compared with neural progenitor cells. In addition, the clinical aggressiveness of malignant gliomas was associated with elevated expression of METTL3. Furthermore, silencing METTL3 or overexpressing dominant-negative mutant METTL3 suppressed the growth and self-renewal of GSCs. Integrated transcriptome and MeRIP-seq analyses revealed that downregulating the expression of METTL3 decreased m 6 A modification levels of serineand arginine-rich splicing factors (SRSF), which led to YTHDC1-dependent NMD of SRSF transcripts and decreased SRSF protein expression. Reduced expression of SRSFs led to larger changes in alternative splicing isoform switches. Importantly, the phenotypes mediated by METTL3 deficiency could be rescued by downregulating BCL-X or NCOR2 isoforms. Overall, these results establish a novel function of m 6 A in modulating NMD and uncover the mechanism by which METTL3 promotes GBM tumor growth and progression.Significance: These findings establish the oncogenic role of m 6 A writer METTL3 in glioblastoma stem cells.

The involvement of circulating microRNAs (miRNAs) in cancer and their potential as biomarkers of diagnosis and prognosis are becoming increasingly appreciated; however, little is known about circulating miRNA profiles in astrocytomas. In our study, we performed genome-wide serum miRNA analysis by the Solexa sequencing followed by validation conducted in the training and verification sets with a stem-loop quantitative reverse-transcription PCR (RT-qPCR) assay from serum samples of 122 untreated astrocytomas patients (WHO grades III-IV) and 123 normal controls. Identified miRNAs were subsequently examined in 55 grade II, 15 grade I astrocytomas, 11 astrogliosis, 42 other primary brain tumors and 8 tumor tissues from grades II-IV astrocytomas. In addition, paired serum samples before and after operation were collected from 14 malignant astrocytomas to determine the effect of surgery on the miRNAs' levels. A marked difference in serum miRNA profile was observed between high-grade astrocytomas and normal controls. Seven miRNAs were validated by RT-qPCR assay to be significantly decreased in grades II-IV patients (p < 0.001), including miR-15b * , miR-23a, miR-133a, miR-150 * , miR-197, miR-497 and miR-548b-5p, and the seven-miRNA panel demonstrated a high sensitivity (88.00%) and specificity (97.87%) for malignant astrocytomas prediction. These identified miRNAs also exhibited a global decrease in tumor tissues relative to normal tissues. Furthermore, these miRNAs in serum were markedly elevated after operation (p < 0.001). In addition, some of these serum miRNAs were significantly different between malignant and benign cases, astrogliosis and other primary brain tumors. The seven serum miRNAs identified in our study hold potential as noninvasive biomarker for malignant astrocytomas.Astrocytomas are the most common primary brain tumors arising from astrocytes, the most abundant type of glial cells of the central nervous system or, more likely, from resident cancer stem cells. Based on their histology and morphological features, astrocytomas are divided into four clinical grades 1 : Grade I (including pilocytic astrocytomas and subependymal giant cell astrocytoma) comprises slowly growing benign astrocytomas, grade II (diffuse astrocytomas and pleomorphic xanthoastrocytoma) represents the least malignant cases and grades III (anaplastic astrocytomas) and IV (glioblastomas or GBM) are highly malignant and have some of the worst survival rates of all human cancers. 1,2 Grade II tumors have an inherent tendency to spontaneously progress to grades III or secondary IV. 1 Surgery followed by chemoradiotherapy is the mainstream of primary grade IV astrocytomas treatment. In the course of postradiation events, however, it is sometimes difficult for neurosurgeons, radiologists and pathologists to discriminate tumor recurrence from radiation necrosis which usually results in astrogliosis. 3,4 Despite the recent advances in therapeutic strategies, such as surgical resection and adjuvant radiotherapy and chemotherapy, the 5-year ...

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Acute myeloid leukemia (AML) is the most common acute leukemia in adults. The disease is characterized by various cytogenetic and molecular abnormalities with distinct prognoses and gene expression profiles. Emerging evidence has suggested that circulating microRNAs (miRNAs) could serve as noninvasive biomarkers for cancer detection; however, little is known about circulating miRNA profiles in AML patients. In this study, a genome-wide serum miRNA expression analysis was performed using Solexa sequencing for initial screen, followed by validation with real-time PCR assays. The analysis was conducted on training and verification sets of serum samples from 140 newly diagnosed AML patients and 135 normal adult donors. After a two-phase selection and validation process, 6 miRNAs, miR-10a-5p, miR-93-5p, miR-129-5p, miR-155-5p, miR-181b-5p and miR-320d, were found to have significantly different expression levels in AML compared with control serum samples. Furthermore, unsupervised clustering analysis revealed the remarkable ability of the 6-miRNA profile to differentiate between AML patients and normal controls. The areas under the ROC curve for the selected miRNAs ranged from 0.8129 to 0.9531. More importantly, miR-181b-5p levels in serum were significantly associated with overall survival. These data demonstrated that the expression patterns of circulating miRNAs were systematically altered in AML and miR-181b-5p may serve as a predictor for overall survival in AML patients.

Right on target: A multifunctional nanoprobe is designed for target‐cell‐specific imaging and in situ detection of intracellular miRNA. The nanoprobe is prepared by functionalizing SnO2 nanoparticles with both folic acid (FA), a target‐cell‐specific moiety to recognize folate receptors overexpressed on cancer cells, and a gene probe to inhibit or recognize intracellular miRNA levels (see scheme).