Background: Circular RNAs (circRNAs) constitute a family of transcripts with unique structures and have been confirmed to be critical in tumorigenesis and to be potential biomarkers or therapeutic targets. However, only a few circRNAs have been functionally characterized in pediatric acute myeloid leukemia (AML). Methods: Here, we investigated the expression pattern of circRNAs in pediatric AML using a circRNA microarray. The characteristics, potential diagnostic value, and prognostic significance of circRNF220 were evaluated. A series of functional experiments were performed to investigate the role of circRNF220 in primary pediatric AML cells. Then we investigated the aberrant transcriptional networks regulated by circRNF220 in primary AML cells by RNA-seq. Furthermore, biotin RNA pulldown assays were implemented to verify the relationship between circRNF220 and miR-30a. Results: We identified a circRNA, circRNF220, which was specifically abundant in and accumulated in the peripheral blood and bone marrow of pediatric patients with AML. It could distinguish AML from ALL and other hematological malignancies with high sensitivity and specificity. Significantly, circRNF220 expression independently predicted prognosis, while high expression of circRNF220 was an unfavorable prognostic marker for relapse. Furthermore, we characterized the function of circRNF220 and found that circRNF220 knockdown specifically inhibited proliferation and promoted apoptosis in AML cell lines and primary cells. Mechanistically, circRNF220 may act as an endogenous sponge of miR-30a to sequester miR-30a and inhibit its activity, which increases the expression of its targets MYSM1 and IER2 and implicated in AML relapse. Conclusions: Collectively, these findings demonstrated that circRNF220 could be highly efficient and specific for the accurate diagnosis of pediatric AML, with implications for relapse prediction.

BACKGROUND: Neuroblastoma is the most frequently diagnosed extracranial solid tumor in children. Previous studies have shown that single‐nucleotide polymorphisms in some genes are associated with the risk of multiple cancers, including neuroblastoma. Although Hox transcript antisense intergenic RNA (HOTAIR) gene polymorphisms have been investigated in a variety of cancers, to the authors' knowledge the relationships between HOTAIR gene polymorphisms and neuroblastoma susceptibility have not been reported to date. The objective of the current study was to evaluate the correlation between HOTAIR gene polymorphisms and neuroblastoma risk in Chinese children.METHODS: The authors genotyped 6 polymorphisms (rs920778 A>G, rs12826786 C>T, rs4759314 A>G, rs7958904 G>C, rs874945 C>T, and rs1899663 C>A) of the HOTAIR gene in 2 Chinese populations including 393 neuroblastoma cases and 812 healthy controls. The strength of the associations was evaluated using odds ratios and 95% confidence intervals. Further stratification analyses were conducted to explore the association between the HOTAIR gene polymorphisms rs12826786 C>T, rs874945 C>T, and rs1899663 C>A with neuroblastoma susceptibility in terms of age, sex, clinical stage of disease, and sites of origin.RESULTS: The authors found that the rs12826786 C>T (P =.013), rs874945 C>T (P =.020), and rs1899663 C>A (P =.029) polymorphisms were significantly associated with increased neuroblastoma risk. In stratification analyses, these associations were more predominant in females and among patients with tumor in the retroperitoneal region or mediastinum. The remaining 3 polymorphisms were not found to be related to neuroblastoma susceptibility.CONCLUSIONS: The results of the current study verified that HOTAIR gene polymorphisms are associated with increased neuroblastoma risk and suggest that HOTAIR gene polymorphisms might be a potential biomarker for neuroblastoma susceptibility. Cancer 2018;124:2599‐606. © 2018 American Cancer Society.

Bmi-1, the B cell-specific moloney murine leukemia virus insertion site 1, is a member of the Polycomb-group (PcG) family and acts as an oncogene in various tumors; however, its expression related to the prognosis of pediatric patients with acute lymphoblastic leukemia (ALL) has not been well studied. The Bmi-1 expression levels in the bone marrow of 104 pediatric ALL patients and 18 normal control subjects were determined by using qRT-PCR. The association between the Bmi-1 expression and the clinicopathological characteristics of pediatric ALL patients was analyzed, and the correlation between Bmi-1 and the prognosis of pediatric ALL was calculated according to the Kaplan–Meier method. Furthermore, the association between Bmi-1 expression and its transcriptional regulator Sall4 was investigated. Compared to normal control subjects, patients with primary pediatric ALL exhibited upregulated levels of Bmi-1. However, these levels were sharply decreased in patients who achieved complete remission. A significant positive association between elevated Bmi-1 levels and a poor response to prednisone as well as an increased clinical risk was observed. Patients who overexpressed Bmi-1 at the time of diagnosis had a lower relapse-free survival (RFS) rate (75.8%), whereas patients with lower Bmi-1 expression had an RFS of 94.1%. Furthermore, in ALL patients, the mRNA expression of Bmi-1 was positively correlated to the mRNA expression of Sall4a. Taken together, these data suggest that Bmi-1 could serve as a novel prognostic biomarker in pediatric primary ALL and may be partially regulated by Sall4a. Our study also showed that Bmi-1 could serve as a new therapeutic target for the treatment of pediatric ALL.

Objective: To reveal the contributing role of METTL3 gene SNPs in pediatric ALL risk.Patients and Methods: A total of 808 pediatric ALL cases and 1,340 cancer-free controls from five hospitals in South China were recruited. A case-control study by genotyping three SNPs in the METTL3 gene was conducted. Genomic DNA was abstracted from peripheral blood. Three SNPs (rs1263801 C>G, rs1139130 A>G, and rs1061027 A>C) in the METTL3 gene were chosen to be detected by taqman real-time polymerase chain reaction assay.Results: That rs1263801 C>G, rs1139130 A>G, and rs1061027 A>C polymorphisms were significantly associated with increased pediatric ALL risk was identified. In stratification analyses, it was discovered that rs1263801 CC, rs1061027 AA, and rs1139130 GG carriers were more likely to develop ALL in subgroups of common B-ALL, MLL gene fusion. Rs1263801 CC and rs10610257 AA carriers were more possible to increase the risk of ALL in subgroups of low hyperdiploid, and all of these three SNPs exhibited a trend toward the risk of ALL. All of these three polymorphisms were associated with the primitive/naïve lymphocytes and MRD in marrow after chemotherapy in ALL children. Rs1263801 CC and rs1139130 AA alleles provided a protective effect on MRD ≥0.01% among CCCG-treated children. As for rs1139130, AA alleles provided a protective effect on MRD in marrow ≥0.01% on 33 days and 12 weeks among CCCG-treated children, but provided a risk effect on MRD in the marrow ≥0.01% among SCCLG-treated children. As for rs1263801 CC and rs1139130 AA, these two alleles provided a protective effect on MRD in the marrow ≥0.01% among CCCG-treated children.Conclusion: In this study, we revealed that METTL3 gene polymorphisms were associated with increased pediatric ALL risk and indicated that METTL3 gene polymorphisms might be a potential biomarker for choosing ALL chemotherapeutics.

Emerging evidence has shown that aberrant microRNA expression has the potential to be used for predicting survival and treatment response of malignant neoplasms. In recent years, the role of miR-9 had been investigated in various types of cancers, and it was found that the results were inconsistent and inconclusive. Hence, in this study, a meta-analysis was conducted to assess the prognostic value of miR-9 in various types of tumors. Eligible studies were identified through a systematic search in PubMed and EMBASE and then were assessed by further quality evaluation. Pooled hazard ratios (HRs) with 95% confidence intervals for overall survival (OS) were calculated to investigate the association between miR-9 expression and cancer prognosis. The pooled results of eight published studies showed that elevated miR-9 was a predictor of poor survival of various carcinomas, with pooled HR of 3.04 (95% confidence interval: 1.96–4.73) for OS. Subgroup analysis on the basis of tumor type, sample size, and HR estimate also showed that high levels of miR-9 were also significantly correlated with OS. In addition, when the subgroup analyses were grouped by follow-up time, it was found that the elevated expression of miR-9 was associated with a lower long-term survival when the follow-up time was >60 months, but there was no correlation between the outcomes and those patients whose follow-up time was <60 months. Funnel plots and Egger’s tests revealed that there was no obvious publication bias risk in the meta-analysis. In conclusion, our results demonstrated that higher expression level of miR-9 significantly predicted worse OS in various carcinomas and that miR-9 may act as a novel biomarker in the prognosis of malignant neoplasms.