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Leukemia is an aberrant hyper-proliferation of immature blood cells that do not form solid tumors. The transcriptomes of microRNAs (miRNAs) of leukemia have been intensively explored. However, miRNA editing of leukemia has not been extensively studied. To identify miRNA editing patterns and explore their functional relevance in leukemia, we analyzed 200 small RNA sequencing profiles of three subtypes of leukemia and identified hundreds of miRNA editing sites in three subtypes of leukemia. Then, we compared the editing levels of identified miRNA editing sites in leukemia and normal controls. Many miRNAs were differential edited in different subtypes of leukemia. We also found the editing levels of 3′-A editing sites of hsa-mir-21-5p and hsa-mir-155-5p decreased in chronic lymphocytic leukemia patients with radiation treatments. By integrating PAR-CLIP sequencing profiles, we predicted the targets of original and edited miRNAs. One of the edited miRNA, hsa-let-7b_5c, with an additional cytosine at 5′ end of hsa-let-7b-5p, potentially targeted VBP1 and CTDSP1. CTDSP1 was significantly downregulated in T-ALL compared to normal controls, which might be originated from the hyperediting of hsa-let-7b-5p in T-ALL. Our study provides a comprehensive view of miRNA editing in three different subtypes of leukemia.

Jianxin Jiang,* Xiaolin Wang,* Jun Lu Department of Neurosurgery, Taizhou People’s Hospital, Taizhou, Jiangsu Province 225300, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jun LuDepartment of Neurosurgery, Taizhou People’s Hospital, M.D 366 Taihu Road, Taizhou, Jiangsu Province 225300, People’s Republic of ChinaTel +86-523-89890321Email lujun83@aol.comObjective: To evaluate the expression and function of long noncoding RNA (lncRNA) Prader-Willi region non-protein coding RNA 1 (PWRN1) in human glioblastoma (GBM).Materials and Methods: QRT-PCR was applied to assess PWRN1 expression in human GBM tumors and GBM cell lines. PWRN1 was overexpressed by lentiviral infection in LN-229 and U-251 cells to evaluate its effect on GBM cell proliferation and migration in vitro, and xenograft in vivo. The endogenously competing target of PWRN1, human microRNA-21-5p (hsa-miR-21-5p) was evaluated by dual-luciferase activity assay and qRT-PCR. Also, hsa-miR-21-5p was upregulated in PWRN1-overexpressed GBM cells to evaluate the functional involvement of hsa-miR-21-5p in PWRN1-mediated GBM cell proliferation and migration.Results: PWRN1 was downregulated in both human GBM tumors and GBM cell lines. In LN-229 and U-251, PWRN1 overexpression suppressed cancer cell proliferation and migration in vitro, and xenograft growth in vivo. Hsa-miR-21-5p was demonstrated to be the downstream competing target of PWRN1 in GBM. Conversely, upregulating hsa-miR-21-5p in LN-229 and U-251 cells reversed the tumor-suppressing effects of PWRN1 overexpression.Conclusion: PWRN1 is markedly downregulated in GBM. Overexpressing PWRN1 has tumor inhibitory effect on GBM cells, likely via reversely suppressing the expression of tumor oncogenic factor of hsa-miR-21-5p.Keywords: GBM, lncRNAs, PWRN1, microRNA, hsa-miR-21-5p, migration

Background/Aims: Circular RNAs (circRNAs), a type of RNA that is widely expressed in human cells, have essential roles in the development and progression of cancer. CircRNAs contain microRNA (miRNA) binding sites and can function as miRNA sponges to regulate gene expression by removing the inhibitory effect of an miRNA on its target gene. Methods: We used the bioinformatics software TargetScan and miRanda to predict circRNA-miRNA and miRNAi-Mrna interactions. Rate of inhibiting of proliferation was measured using a WST-8 cell proliferation assay. Clone formation ability was assessed with a clone formation inhibition test. Cell invasion and migration capacity was evaluated by performing a Transwell assay. Relative gene expression was assessed using quantitative real-time polymerase chain reaction and relative protein expression levels were determined with western blotting. circRNA and miRNA interaction was confirmed by dual-luciferase reporter and RNA-pull down assays. Results: In the present study, the miRNA hsa-miR-21-5p was a target of circRNA-ACAP2, and T lymphoma invasion and metastasis protein 1 (Tiam1) was identified as a target gene of hsa-miR-21-5p. CircRNA-ACAP2 and Tiam1 were shown to be highly expressed in colon cancer tissue and colon cancer SW480 cells, but miR-21-5p was expressed at a low level. SW480 cell proliferation was suppressed when the expression of circRNA-ACAP2 and Tiam1 was decreased and the expression of miR-21-5p was increased in vivo and in vitro. SW480 cell migration and invasion were also inhibited under the same circumstance. The circRNA-ACAP2 interaction regulated the expression of miR-21-5p, and miR-21-5p regulated the expression of Tiam1. Down-regulation of circRNA-ACAP2 promoted miR-21-5p expression, which further suppressed the transcription and translation of Tiam1. Conclusion: The present study shows that the circRNA-ACAP2/hsa-miR-21-5p/Tiam1 regulatory feedback circuit could affect the proliferation, migration, and invasion of colon cancer SW480 cells. This was probably due to the fact that circRNA-ACAP2 could act as a miRNA sponge to regulate Tiam1 expression by removing the inhibitory effect of miR-21-5p on Tiam1 expression. The results from this study have revealed new insights into the pathogenicity of colon cancer and may provide novel therapeutic targets for the treatment of colon cancer.

High-density lipoproteins provide protection against the damaging effects of glucolipotoxicity in beta cells, a factor which sustains insulin secretion and staves off onset of type 2 diabetes mellitus. This study examines epigenetic changes in small non-coding microRNA sequences induced by high density lipoproteins in a human hybrid beta cell model, and tests the impact of delivery of a single sequence in protecting against glucolipotoxicity. Human PANC-1.1B4 cells were used to establish Bmax and Kd for [3H]cholesterol efflux to high density lipoprotein, and minimum concentrations required to protect cell viability and reduce apoptosis to 30mM glucose and 0.25 mM palmitic acid. Microchip array identified the microRNA signature associated with high density lipoprotein treatment, and one sequence, hsa-miR-21-5p, modulated via delivery of a mimic and inhibitor. The results confirm that low concentrations of high-density lipoprotein can protect against glucolipotoxicity, and report the global microRNA profile associated with this lipoprotein; delivery of miR-21-5p mimic altered gene targets, similar to high density lipoprotein, but could not provide sufficient protection against glucolipotoxicity. We conclude that the complex profile of microRNA changes due to HDL treatment may be difficult to replicate using a single microRNA, findings which may inform current drug strategies focused on this approach.