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Background: The activation of NF-κB signaling pathway is regarded as the dominant process that correlates with tumorigenesis. Recently, increasing evidence shows that long noncoding RNAs (lncRNAs) play crucial roles in sustaining the NF-κB signaling pathway. However, the underlying mechanisms have not yet been elucidated., Methods: The expression and clinical features of PLACT1 were analyzed in a 166-case cohort of PDAC by qRT-PCR and in situ hybridization. The functional role of PLACT1 was evaluated by both in vitro and in vivo experiments. Chromatin isolation by RNA purification assays were utilized to examine the interaction of PLACT1 with IκBα promoter., Results: We identified a novel lncRNA-PLACT1, which was significantly upregulated in tumor tissues and correlated with progression and poor survival in PDAC patients. Moreover, PLACT1 promoted the proliferation and invasion of PDAC cells in vitro. Consistently, PLACT1 overexpression fostered the progression of PDAC both in orthotopic and lung metastasis mice models. Mechanistically, PLACT1 suppressed IκBα expression by recruiting hnRNPA1 to IκBα promoter, which led to increased H3K27me3 that decreased the transcriptional level of IκBα. Furthermore, E2F1-mediated overexpression of PLACT1 modulated the progression of PDAC by sustained activation of NF-κB signaling pathway through forming a positive feedback loop with IκBα. Importantly, administration of the NF-κB signaling pathway inhibitor significantly suppressed PLACT1-induced sustained activation of NF-κB signaling pathway, leading to reduced tumorigenesis in vivo., Conclusions: Our findings suggest that PLACT1 provides a novel epigenetic mechanism involved in constitutive activation of NF-κB signaling pathway and may represent a new therapeutic target of PDAC.

Background: MicroRNA-122 (miR-122), a pivotal liver-specific miRNA, is frequently repressed in hepatocellular carcinoma (HCC) and associated with poor prognosis. Long non-coding RNA (lncRNA) HOTAIR has been proved to function as an oncogene in multiple cancers including HCC. However, the relationship between HOTAIR and miR-122 in HCC remains largely unknown., Methods: We investigated the function of HOTAIR and miR-122 in HCC cell models and a xenograft mouse model. The regulatory network between HOTAIR and miR-122 was further detected following overexpression or knockdown of HOTAIR. DNA methylation status of miR-122 promoter region, as well as expression levels of DNMTs, EZH2 and Cyclin G1 were analyzed., Findings: In this study, we found that HOTAIR was highly expressed whereas miR-122 was suppressed in HCC, and HOTAIR negatively regulated miR-122 expression in HCC cells. Furthermore, knockdown of HOTAIR dramatically inhibited HCC cell proliferation and induced cell cycle arrest in vitro and suppressed tumorigenicity in vivo by upregulating miR-122 expression. Mechanistically, a CpG island was located in the miR-122 promoter region. HOTAIR epigenetically suppressed miR-122 expression via DNMTs-mediated DNA methylation. Moreover, HOTAIR upregulated DNMTs expression via EZH2. In addition, suppression of miR-122 induced by HOTAIR directly reactivated oncogene Cyclin G1 expression. Collectively, our results suggest that HOTAIR epigenetically suppresses miR-122 expression via DNA methylation, leading to activation of Cyclin G1 and promotion of tumorigenicity in HCC, which provide new insight into the mechanism of HOTAIR-mediated hepatocarcinogenesis via suppressing miR-122., (Copyright © 2018. Published by Elsevier B.V.)

Long non-coding RNAs (lncRNAs) play a pivotal role in pathological processes. However, little information has been published regarding the underlying functions and mechanisms of lncRNAs in pancreatic ductal adenocarcinoma (PDAC). A novel lncRNA FEZF1-AS1 and its sense-cognate gene ZNF312B were found to be highly expressed in human PDAC tissues and cell lines, which is associated with disease progression and predicts clinical outcome in PDAC patients. Of note, bioinformatics analysis, luciferase assays and RNA immunoprecipitation assays indicated that FEZF1-AS1 may act as an endogenous sponge by competing for miR-107, thereby modulating the derepression of ZNF312B. Downregulation of FEZF1-AS1 or ZNF312B significantly inhibited proliferation, colony formation, migration, and invasion of PDAC cells in vitro, whereas the miR-107 inhibitor abrogated the effect of dow-regulation of FEZF1-AS1 or ZNF312B in reducing oncogenic capacities of PDAC cells. In addition, FEZF1-AS1/miR-107/ZNF312B axis-induced promotion of PDAC cells proliferation appeared to be mediated by modulation of the apoptosis and the G1-S checkpoint. Furthermore, downregulation of FEZF1-AS1 repressed tumor growth in mouse xenograft models. In particular, our results highlight the contribution of FEZF1-AS1/miR-107/ZNF312B axis to Warburg effect maintenance of PDAC cells. Collectively, our findings demonstrate that the FEZF1-AS1/miR-107/ZNF312B axis regulatory network might provide a potential new therapeutic strategy for PDAC.

Background/aims: Long noncoding RNAs (lncRNAs) are key regulators of cancer initiation and progression. In this study, we investigated the clinical value and functional role of LncRNA DQ786243 (LncDQ) in the pathogenesis of hepatocellular carcinoma (HCC)., Methods: To investigate the expression level of LncDQ in HCC, we performed quantitative real-time PCR using total RNA extracted from HCC tumor tissues and their matched non-neoplastic counterparts, as well as from the serum of HCC patients and healthy volunteers. The correlation of LncDQ expression with clinicopathologic features and prognosis was analyzed. The functional role of LncDQ in cell proliferation, migration, and invasion were evaluated by MTT cell viability, wound healing, and transwell assays in vitro and in vivo. RNA immunoprecipitation and chromatin immunoprecipitation assays were performed to analyze the potential mechanism of LncDQ in HCC cells., Results: LncDQ was upregulated in both HCC tissue samples and serum and was correlated with low survival rate and adverse clinical pathological characteristics. Multivariate analysis demonstrated that LncDQ expression was an independent prognostic factor for HCC. The area under the receiver operating characteristic curve was 0.804 with a sensitivity of 0.72 and a specificity of 0.8. Knockdown of LncDQ induced inhibition of cell proliferation, migration, and invasion in vitro and in vivo. Mechanistically, LncDQ regulated the epithelial-mesenchymal transition pathway by interacting with EZH2, to epigenetically repress the expression of E-cadherin in HCC cells., Conclusions: Taken together, the results of our study indicate that LncDQ plays a critical role in HCC progression, and may serve as a potential diagnostic and prognostic biomarker for HCC., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Our previous study demonstrated that long non-coding RNA (lncRNA) HOTTIP was maximally expressed in PDAC, and promoted cancer cell progression and epithelial to mesenchymal transition (EMT). Numerous studies indicated that lncRNAs or EMT supported cancer stem cells. However, the role of HOTTIP in pancreatic cancer stem cells (PCSCs) remains unclear. Here, we evaluated the role and mechanism of HOTTIP in PCSCs. First, we analyzed the relationship between HOTTIP expression and overall or disease-free survival in 90 patients with PDAC after radical resection. Patients with higher HOTTIP expression had shorter disease-free survival and overall survival than those with lower expression. Expression of HOTTIP and other lncRNAs was detected in PCSCs and non-PCSCs by laser capture microdissection (LCM). HOTTIP was highly expressed in PCSCs. In addition, in vitro assays showed that HOTTIP alterations affected stemness, including sphericity, tumorigenesis, and stem factors (LIN28, NANOG, OCT4, and SOX2) and markers (ALDH1, CD44, and CD133). Mechanistically, HOTTIP mediated HOXA9 to enhance the Wnt/β-catenin pathway by binding to WDR5 in PCSCs. In vivo results showed that HOTTIP or HOXA9 alterations influenced stemness. Our results indicate that the HOTTIP/WDR5/HOXA9/Wnt axis contributes to PCSC stemness and is a potential therapeutic target for PDAC., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

Long non-coding RNAs (lncRNAs) are important regulators in pathological processes, yet their potential roles in pancreatic ductal adenocarcinoma (PDAC) are poorly understood. Here, we found that a novel lncRNA, LOC389641, was upregulated in PDAC tissues and cell lines. The expression of LOC389641 was significantly correlated with staging, lymph node metastasis and overall survival. Knockdown of LOC389641 impaired cell proliferation and invasion and induced cell apoptosis in vitro, whereas overexpression of LOC389641 had the opposite effect. The growth promoting effect of LOC389641 was also demonstrated in vivo. Further, a significant negative correlation was observed between E-cadherin levels and LOC389641 levels in vivo. Knockdown of LOC389641 upregulated E-cadherin expression, but knockdown of E-cadherin had a limited influence on LOC389641. Importantly, after E-cadherin was inhibited, the enhancement of LOC389641 on cell invasion was hindered. Moreover, the expression of LOC389641 was closely associated with its genomic neighboring gene TNFRSF10A. Lastly, knockdown experiments showed that TNFRSF10A might be a connection between LOC389641and E-cadherin. We conclude that LOC389641 promotes PDAC progression and increases cell invasion by regulating E-cadherin with the possible involvement of TNFRSF10A., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Long non-coding RNAs (lncRNAs) have shown great potential as powerful and non-invasive tumor markers. However, little is known about their value as biomarkers in pancreatic cancer (PC). We applied an Arraystar Human LncRNA Microarray which targeting 7419 lncRNAs to determine the lncRNA expression profile in PC and to screen the potential biomarkers. The most increased lncRNAs in PC tissues were HOTTIP-005, XLOC&#95;006390, and RP11-567G11.1. Increased HOTTIP-005 and RP11-567G11.1 expression were poor prognostic factors for patients with PC (n = 144, p < 0.0001). The expression patterns of HOTTIP splice variants in PC were also detected. HOTTIP-005 and HOTTIP-001 were the first and second most increased HOTTIP splice variants, respectively. Plasma HDRF and RDRF (HOTTIP-005 and RP11-567G11.1 derived RNA fragments in plasma/serum) were present in stable form. Their levels were significantly increased in the patients with PC as compared to the healthy controls (n = 127 and 122 respectively, p < 0.0001) and the high levels were derived from PC. HDRF and RDRF levels are promising indicators for distinguishing patients with PC from those without PC. This study identified HOTTIP-005 and RP11-567G11.1 and their plasma fragments with the potential to be used as prognostic and diagnostic biomarkers of PC. Further large-scale prospective studies are needed to confirm our findings.

Background: The human genome encodes many long non-coding RNAs (lncRNAs). However, their biological functions, molecular mechanisms, and the prognostic value associated with pancreatic ductal adenocarcinoma (PDAC) remain to be elucidated. Here, we identify a fundamental role for the lncRNA HOXA transcript at the distal tip (HOTTIP) in the progression and chemoresistance of PDAC., Methods: High-throughput microarrays were performed to detect the expression profiles of lncRNAs and messenger RNAs in eight human PDAC tissues and four pancreatic tissues. Quantitative real-time PCR was used to determine the levels of HOTTIP and HOXA13 transcripts in PDAC cell lines and 90 PDAC samples from patients. HPDE6 cells (immortalized human pancreatic ductal epithelial cells) and corresponding adjacent non-neoplastic tissues were used as controls, respectively. The functions of HOTTIP and HOXA13 in cell proliferation, invasion, and epithelial-mesenchymal transition were evaluated by targeted knockdown in vitro. CCK-8 assays, colony formation assays, and xenografts in nude mice were used to investigate whether targeted silencing of HOTTIP could sensitize pancreatic cancer cells to gemcitabine. Immunohistochemistry was performed to investigate the relationship between HOXA13 expression and patient outcome., Results: Microarray analyses revealed that HOTTIP was one of the most significantly upregulated lncRNAs in PDAC tissues compared with pancreatic tissues. Quantitative PCR further verified that HOTTIP levels were increased in PDAC cell lines and patient samples compared with controls. Functionally, HOTTIP silencing resulted in proliferation arrest by altering cell-cycle progression, and impaired cell invasion by inhibiting epithelial-mesenchymal transition in pancreatic cancer. Additionally, inhibition of HOTTIP potentiated the antitumor effects of gemcitabine in vitro and in vivo. Furthermore, knockdown of HOXA13 by RNA interference (siHOXA13) revealed that HOTTIP promoted PDAC cell proliferation, invasion, and chemoresistance, at least partly through regulating HOXA13. Immunohistochemistry results revealed that higher HOXA13 expression was correlated with lymph node metastasis, poor histological differentiation, and decreased overall survival in PDAC patients., Conclusions: As a crucial tumor promoter, HOTTIP promotes cell proliferation, invasion, and chemoresistance by modulating HOXA13. Therefore, the HOTTIP/HOXA13 axis is a potential therapeutic target and molecular biomarker for PDAC.