C/EBPβ contributes to transcriptional activation of long non-coding RNA NEAT1 during APL cell differentiation

Cytoplasmic NEAT1 Suppresses AML Stem Cell Self-Renewal and Leukemogenesis through Inactivation of Wnt Signaling

As an essential component of paraspeckles, nuclear paraspeckle assembly transcript 1 (NEAT1) localizes in the nucleus, promoting progression of various malignant solid tumors. Herein, an adverse effect of NEAT1 is reported, showing that the short isoform, NEAT1_1 suppresses acute myeloid leukemia (AML) development. NEAT1_1 is downregulated in leukemia stem cells (LSCs) and its decreased expression correlates with recurrence in AML patients. It is demonstrated that NEAT1_1 suppresses leukemogenesis and LSC function but is dispensable for normal hematopoiesis. Mechanistically, NEAT1_1 is released from the nucleus into the cytoplasm of AML cells, regulated by transcription factor C/EBPβ and nuclear protein NAP1L1. Cytoplasmic NEAT1_1 interacts with Wnt component DVL2 and E3 ubiquitin ligase Trim56, facilitates Trim56-mediated DVL2 degradation, and thus suppresses Wnt signaling. Collectively, the findings show NEAT1_1 is translocated from the nucleus to the cytoplasm and acts as a tumor suppressor in AML.

C/EBPα is indispensable for PML/RARα-mediated suppression of long non-coding RNA NEAT1 in acute promyelocytic leukemia cells

Better understanding of the transcriptional regulatory network in acute promyelocytic leukemia (APL) cells is critical to illustrate the pathogenesis of other types of acute myeloid leukemia. Previous studies have primarily focused on the retinoic acid signaling pathway and how it is interfered with by promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion protein. However, this hardly explains how APL cells are blocked at the promyelocytic stage. Here, we demonstrated that C/EBPα bound and transactivated the promoter of long non-coding RNA NEAT1, an essential element for terminal differentiation of APL cells, through C/EBP binding sites. More importantly, PML/RARα repressed C/EBPα-mediated transactivation of NEAT1 through binding to NEAT1 promoter. Consistently, mutation of the C/EBP sites or deletion of retinoic acid responsive elements (RAREs) and RARE half motifs abrogated the PML/RARα-mediated repression. Moreover, silencing of C/EBPα attenuated ATRA-induced NEAT1 upregulation and APL cell differentiation. Finally, simultaneous knockdown of C/EBPα and C/EBPβ reduces ATRA-induced upregulation of C/EBPε and dramatically impaired NEAT1 activation and APL cell differentiation. In sum, C/EBPα binds and transactivates NEAT1 whereas PML/RARα represses this process. This study describes an essential role for C/EBPα in PML/RARα-mediated repression of NEAT1 and suggests that PML/RARα could contribute to the pathogenesis of APL through suppressing C/EBPα targets.

Isobavachalcone inhibits acute myeloid leukemia: Potential role for ROS-dependent mitochondrial apoptosis and differentiation

Isobavachalcone (IBC) has been shown to induce apoptosis and differentiation of acute myeloid leukemia (AML) cells. However, the underlying molecular mechanisms are not fully understood. Herein, IBC exhibited significant inhibition on the cell viability, proliferation, and the colony formation ability of AML cells. Moreover, IBC induced mitochondrial apoptosis evidenced by reduced mitochondrial membrane potential, increased Bax level, decreased Bcl-2, Bcl-xL, and Mcl-1 levels, elevated cytochrome c level in the cytosol and increased cleavage of caspase-9, caspase-3, and PARP. Furthermore, IBC obviously promoted the differentiation of AML cells, accompanied by the increase of the phosphorylation of MEK and ERK and the C/EBPα expression as well as the C/EBPβ LAP/LIP isoform ratio, which was significantly reversed by U0126, a specific inhibitor of MEK. Notably, IBC enhanced the intracellular ROS level. More importantly, IBC-induced apoptosis and differentiation of HL-60 cells were significantly mitigated by NAC. In addition, IBC also exhibited an obvious anti-AML effect in NOD/SCID mice with the engraftment of HL-60 cells. Together, our study suggests that the ROS-medicated signaling pathway is highly involved in IBC-induced apoptosis and differentiation of AML cells.

lncRNA RHPN1-AS1 Serves as a Sponge for miR-3133 Modulating the Cell Proliferation of Retinoblastoma through JAK2

Purpose

To investigate the effects of lncRNA RHPN1-AS1 on retinoblastoma (RB) and further explore its underlying molecular mechanisms.

Methods

The expression of RHPN1-AS1, miR-3133, (JAK2), and signal transducer and activator of transcription 3 (STAT3) was detected by qRT-PCR. CCK-8, EDU, and flow cytometry assays were conducted to assess the proliferation activity and apoptosis of RB cells. Double fluorescein and RNA immunoprecipitation assays were performed to detect the interaction between RHPN1-AS1 and miR-3133 or miR-3133 and JAK2. Western blotting was performed to detect the expression of apoptosis-related proteins.

Results

In RB cells, RHPN1-AS1 was upregulated. Silencing RHPN1-AS1 inhibited the activity of RB cells and promoted apoptosis. The expressions of proapoptotic factors (Bax and p53) were increased, while antiapoptotic factors (Bcl-2 and Survivin) were suppressed in siRHPN1-AS1 groups. Furthermore, we predicted and verified that RHPN1-AS1 regulated RB progression by targeting miR-3133/JAK2. In addition, siRHPN1-AS1 also inhibited oncogene STAT3 protein expression.

Conclusion

lncRNA RHPN1-AS1 served as a sponge for miR-3133 to counteract miR-3133-mediated JAK2/STAT3 suppression, indicating that the lncRNA RHPN1-AS1 may be a potential therapeutic target for the treatment of RB.

Long non-coding RNA HOTAIR regulates myeloid differentiation through the upregulation of p21 via miR-17-5p in acute myeloid leukaemia

Long non-coding RNA HOTAIR has been reported to play a key role in regulating various biological processes in various cancers. However, the roles and mechanisms of HOTAIR in acute myeloid leukaemia (AML) are still unclear and need to be investigated. In this study, we induced differentiation of four AML cell lines by all-trans retinoic acid (ATRA) and found HOTAIR was significantly upregulated in the process. Chromatin immunoprecipitation (ChIP) assays indicated that C/EBPβ upregulated HOTAIR during ATRA induced differentiation in HL-60 cells. By gain- and loss-of-function analysis, we then observed that HOTAIR expression was positively correlated with ATRA-induced differentiation and negatively regulated G1 phase arrest in HL-60 cells. In addition, we found that HOTAIR promoted ATRA-induced differentiation via the regulation of the cell cycle regulator p21 via miR-17-5p. Moreover, we detected the expression of HOTAIR in 84 de novo AML patients, HOTAIR was found significantly downregulated in the AML patients compared to the iron deficiency anaemia (IDA) control group, negatively correlated with the platelet level in M2 patients. In all, our data suggest that HOTAIR may be subtype-specific in AML-M2 patients, also HOTAIR regulates AML differentiation by C/EBPBβ/HOTAIR/miR-17-5p/p21 pathway. The findings of the present study provide a novel insight into the mechanism of lncRNA-mediated differentiation and indicate that HOTAIR may be a promising therapeutic target for leukaemia, especially for AML with M2 type.Abbreviation: AML: acute myeloid leukaemia; APL: acute promyelocytic leukaemia; ATRA: all-trans retinoic acid; CCK8: cell Counting Kit-8; CDKs: cyclin-dependent kinases ; CeRNA: competing endogenous RNAs; ChIP: chromatin immunoprecipitation; CHX: cycloheximide; FAB: French-American-British; FCM: flow cytometry; HOTAIR: HOX transcript antisense RNA; IDA: iron-deficiency anemia; lncRNA: long non-coding RNA; 3'UTR: 3'untranslated region; MT: Mutation type; WT: Wild type; qRT-PCR: Quantitative real-time PCR.

lncRNA EZR‑AS1 knockdown represses proliferation, migration and invasion of cSCC via the PI3K/AKT signaling pathway

Although long non-coding RNAs (lncRNAs) have been implicated in various human cancer types, the role of lncRNA ezrin antisense RNA 1 (EZR-AS1) in cutaneous squamous cell carcinoma (cSCC) remains unclear. The present study aimed to investigate the effect of lncRNAEZR-AS1 on cSCC and identify the underlying molecular mechanisms. EZR-AS1 expression was measured in cSCC tissue and cells detected using reverse transcription-quantitative PCR. Gain-of-function assays were performed in A431 cells, which have a relatively low expression of EZR-AS1, while loss-of-function assays were performed in SCC13 and SCL-1 colon cancer cells, which have a relatively high expression of EZR-AS1. Cell viability, proliferation, migration, invasion and apoptosis were assessed using MTT, plate cloning, wound healing, Transwell and flow cytometry assays, respectively. EZR-AS1 mRNA expression levels were significantly upregulated in cSCC tissues and cells compared with adjacent healthy tissues and HaCaT cells, respectively. Compared with the small interfering RNA (si)-negative control (NC) group, si-EZR-AS1 significantly inhibited SCC13 and SCL-1 cell proliferation, migration and invasion, but promoted cell apoptosis. By contrast, compared with the pc-NC group, EZR-AS1 overexpression significantly enhanced A431 cell proliferation, migration and invasion, but inhibited cell apoptosis. Moreover, focal adhesion kinase (FAK) was identified as a target of EZR-AS1, and EZR-AS1 knockdown significantly decreased FAK expression compared with the si-NC group. Moreover, EZR-AS1 knockdown significantly downregulated the protein expression levels of phosphorylated (p)-PI3K/PI3K and p-AKT/AKT in cSCC cells compared with the si-NC group. The PI3K agonist 740Y-P significantly reversed si-EZR-AS1-mediated effects on SCC13 and SCL-1 cell proliferation, migration, invasion and apoptosis. In conclusion, the present study demonstrated that si-EZR-AS1 inhibited cSCC cell proliferation, migration and invasion, and promoted cell apoptosis, potentially via regulating the PI3K/AKT signaling pathway. Therefore, the present study provided novel insights into the diagnosis and treatment of cSCC.

Long non-coding RNA NEAT1-centric gene regulation

Nuclear paraspeckle assembly transcript 1 (NEAT1) is a long non-coding RNA that is widely expressed in a variety of mammalian cell types. An increasing number of studies have demonstrated that NEAT1 plays key roles in various biological and pathological processes; therefore, it is important to understand how its expression is regulated and how it regulates the expression of its target genes. Recently, we found that NEAT1 expression could be regulated by signal transducer and activator of transcription 3 and that altered NEAT1 expression epigenetically regulates downstream gene transcription during herpes simplex virus-1 infection and Alzheimer's disease, suggesting that NEAT1 acts as an important sensor and effector during stress and disease development. In this review, we summarize and discuss the molecules and regulatory patterns that control NEAT1 gene expression and the molecular mechanism via which NEAT1 regulates the expression of its target genes, providing novel insights into the central role of NEAT1 in gene regulation.

Knockdown of LncRNA RHPN1-AS1 Inhibits Cell Migration, Invasion and Proliferation in Head and Neck Squamous Cell Carcinoma

Previous studies have revealed that long non-coding RNAs (lncRNAs) are involved in head and neck squamous cell carcinoma (HNSCC) progression. However, the detailed roles of lncRNA RHPN1-AS1 remain to be elucidated. In this study, by analyzing online RNA-Seq data, we found that RHPN1-AS1 was upregulated in HNSCC tissues and that its expression level was associated with neoplasm histologic grade. High expression of RHPN1-AS1 was also confirmed in HNSCC tissues. Knockdown of RHPN1-AS1 inhibited tumor cell migration, invasion and proliferation in HNSCC. Furthermore, inhibition of RHPN1-AS1 suppressed the expression of epithelial-mesenchymal transition (EMT)-related genes (β-Catenin, Claudin-1 and Vimentin) in HNSCC cells. Collectively, our results suggest that RHPN1-AS1, acting as an oncogene, may be a potential diagnostic and therapeutic target in HNSCC.

Co-expression Network Analysis Revealing the Potential Regulatory Roles of lncRNAs in Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common types of dementia among the elderly. Previous studies had revealed that the dysregulation of lncRNAs played important roles in human diseases, including AD. However, there is still a lack of comprehensive analysis of differently expressed long non-coding RNAs (lncRNAs) in different distinct regions related to AD. In present study, we identified a total of 678, 593, 941, 1445, 1179, 466 differently expressed lncRNAs that were found in entorhinal cortex (EC), middle temporal gyrus(MTG), hippocampus (HIP), superior frontal gyrus (SFG), posterior cingulate (PC), cortex and primary visual cortex (VCX) AD samples, respectively. Furthermore, we constructed lncRNA-mRNA co-expression networks in AD to explore the potential roles of these lncRNAs. Differentially expressed (DE) lncRNAs were involved in regulating metabolic process, respiratory electron transport chain and ATP metabolic process showed by GO analysis. Interestingly, KEGG analysis revealed these lncRNAs were associated with neurodegenerative disorders such as Alzheimer's disease, Huntington's disease and Parkinson's disease. Four lncRNAs (LOC100507557, LOC101929787, NEAT1, and JAZF1-AS1) were identified as key lncRNAs in AD progression and dysregulated in different distinct regions related to AD. Our study has uncovered several key lncRNAs in AD, which would give novel underlying therapeutic and prognostic targets for AD.

C/EBPβ promotes the viability of human bladder cancer cell by contributing to the transcription of bladder cancer specific lncRNA UCA1

Urothelial Carcinoma Antigen 1 (UCA1) is a cell and tissue specific long non-coding RNA (lncRNA) associated with the tumorigenesis and invasion of bladder cancer. However, the mechanism driving the over-transcription of UCA1 in bladder cancer cells remains unclear. It has been reported that C/EBPβ has a significant role of regulation in tumorigenesis. Here we report that the expression of UCA1 was dramatically inhibited in 5637 cells with C/EBPβ down-regulation. Additionally, the function tests indicated that C/EBPβ could promote 5637 cells growth and colony formation by inducing the expression level of UCA1. These data suggest that C/EBPβ was involved in transcriptional regulation of UCA1 and contributed substantially to its high expression and proliferation promoting in bladder cancer cells.

Long noncoding RNA NEAT1 (nuclear paraspeckle assembly transcript 1) is critical for phenotypic switching of vascular smooth muscle cells

In response to vascular injury, vascular smooth muscle cells (VSMCs) may switch from a contractile to a proliferative phenotype thereby contributing to neointima formation. Previous studies showed that the long noncoding RNA (lncRNA) NEAT1 is critical for paraspeckle formation and tumorigenesis by promoting cell proliferation and migration. However, the role of NEAT1 in VSMC phenotypic modulation is unknown. Herein we showed that NEAT1 expression was induced in VSMCs during phenotypic switching in vivo and in vitro. Silencing NEAT1 in VSMCs resulted in enhanced expression of SM-specific genes while attenuating VSMC proliferation and migration. Conversely, overexpression of NEAT1 in VSMCs had opposite effects. These in vitro findings were further supported by in vivo studies in which NEAT1 knockout mice exhibited significantly decreased neointima formation following vascular injury, due to attenuated VSMC proliferation. Mechanistic studies demonstrated that NEAT1 sequesters the key chromatin modifier WDR5 (WD Repeat Domain 5) from SM-specific gene loci, thereby initiating an epigenetic "off" state, resulting in down-regulation of SM-specific gene expression. Taken together, we demonstrated an unexpected role of the lncRNA NEAT1 in regulating phenotypic switching by repressing SM-contractile gene expression through an epigenetic regulatory mechanism. Our data suggest that NEAT1 is a therapeutic target for treating occlusive vascular diseases.