Ultrafast vibrational energy redistribution in cyclotrimethylene trinitramine (RDX).

The microscopic mechanism of the energy transfer in cyclotrimethylene trinitramine (RDX) is of particular importance for the study of the energy release process in high-energy materials. In this work, an effective vibrational Hamiltonian based on normal modes (NMs) has been introduced to study the energy transfer process of RDX. The results suggest that the energy redistribution in RDX can be characterized as an ultrafast process with a time scale of 25 fs, during which the energy can be rapidly localized to the -NNO2 twisting mode (vNNO2), the N-N stretching mode (vN-N), and the C-H stretching mode (vC-H). Here, the vNNO2 and vN-N modes are directly related to the cleavage and dissociation of the N-N bond in RDX and, therefore, can be referred to as "active modes." More importantly, we found that the energy can be rapidly transferred from the vC-H mode to the vNNO2 mode due to their strong coupling. From this perspective, the vC-H mode can be regarded as an "energy collector" that plays a pivotal role in supplying energy to the "active modes." In addition, the bond order analysis shows that the dissociation of the N-N bonds of RDX follows a combined twisting and stretching path along the N-N bond. This could be an illustration of the further exothermic decomposition triggered by the accumulation of vibrational energy. The present study reveals the microscopic mechanism for the vibrational energy redistribution process of RDX, which is important for further investigation of the energy transfer process in high-energy materials.

Discovery of 2,4-diarylaminopyrimidine derivatives bearing sulfonamide moiety as novel FAK inhibitors.

Two series of 2,4-diarylaminopyrimidine derivatives containing sulfonamide moiety were designed and synthesized for screening as inhibitors of focal adhesion kinase (FAK). Most compounds significantly inhibited the enzymatic activities of FAK, and the best compound was 7b (IC50 = 0.27 nM). A majority of aminoethyl sulfonamide derivatives could effectively inhibit the proliferation of human cancer cell lines (HCT116, A549, MDA-MB-231 and Hela) expressing high levels of FAK. Particularly, compounds 7b, 7c, and 7o exhibited more significant efficacy against all of four cancer cell lines within concentrations of 1.5 µM. Furthermore, these three compounds displayed higher selectivity of cancer cells over normal cells (SI value > 14), compared to the positive control TAE226 (SI value = 1.63). Interestingly, introduction of dithiocarbamate moiety to the aminoethyl sulfonamide derivatives can indeed improve the antiproliferative activities against A549 cells. Especially, compound 8d demonstrated most significant cytotoxicity activity against A549 cells with an IC50 value of 0.08 µM, which is 20-fold superior to parent compound 7k. Additionally, compound 7b, which display the best anti-FAK potency, can inhibit the clone formation and migration of HCT-116 cells, and cause cell cycle arrest at G2/M phase, inducing apoptosis by promoting ROS production. Overall, these results suggest that 7b is a valuable FAK inhibitor that deserves further optimization to improve its druggability.

PLCL1 suppresses tumour progression by regulating AMPK/mTOR-mediated autophagy in renal cell carcinoma.

Autophagy has been increasingly recognized as a critical regulatory mechanism in the maintenance of cellular homeostasis. A previous study showed that phospholipase C-like protein 1 (PLCL1) is associated with lipid metabolism in renal cell carcinoma (RCC). However, it is unclear whether PLCL1 regulates autophagy, thereby influencing the progression of RCC. Bioinformatics analysis of five microarray datasets revealed that expression of PLCL1 is decreased in tumours and is positively correlated with prognosis in RCC patients. Three independent public datasets, clinical RCC tissues and RCC cell lines, were validated using real-time qPCR, western blotting and immunohistochemistry. Using wound healing and transwell assays, we observed that elevated PLCL1 levels decreased the migratory distance and the invasive number of 786-O and ACHN cells, but PLCL1 knockdown reversed these changes in 769P cell lines compared to those in controls. The results of flow cytometry analysis indicated that PLCL1 promotes apoptosis. Moreover, transcriptional analysis based on stable overexpression of PLCL1 in 786-O cells revealed that PLCL1 is related to autophagy, and western blotting and autophagic experimental results further verified these findings. Mechanistic investigations confirmed that PLCL1 activates the AMPK/mTOR pathway and interacts with decidual protein induced by progesterone (DEPP). Collectively, our data suggest that PLCL1 functions as a suppressor of RCC progression by activating the AMPK/mTOR pathway, interacting with DEPP, initiating autophagy and inducing apoptosis. PLCL1 may be a promising therapeutic target for the diagnosis and treatment of ccRCC patients.

The Influence of Hydrogen Bonds on the Roaming Reaction.

Roaming bypasses the conventional transition state and is a significant reaction pathway due to the unusual energy distributions of its products; however, its reaction pathway under external environmental interactions remains unclear. Herein, we report for the first time the roaming process of nitrobenzene, which is influenced by the hydrogen bonds (H-bonds) between nitro- and phenyl radicals and water molecules in the gas phase. Notably, despite the fact that the single water structure produces a higher but narrower barrier, whereas the double water structure leads to a lower but wider barrier, the roaming reaction still occurs. The underlying mechanism responsible for these influences of H-bonds is ascribed to the dramatically changed polarization and correlation interactions between the roaming radicals. The reaction rates and thermal perturbation probabilities are also remarkably influenced due to the presence of the H-bonds, by approximately 2 orders of magnitude. It is anticipated that this work will encourage the promising feasibility of introducing environmental molecules to modulate the roaming reaction.

Integrative analysis of deoxyribonuclease 1-like 3 as a potential biomarker in renal cell carcinoma.

Background: Clear cell renal cell carcinoma (ccRCC), the most common subtype of renal cell carcinoma (RCC), is insensitive to radiotherapy and chemotherapy after surgery. Deoxyribonuclease 1-like 3 (DNASE1L3), an endonuclease that cleaves both membrane-encapsulated single- and double-stranded DNA, suppresses cell cycle progression, proliferation and metabolism in hepatocellular carcinoma cells. There is currently no established link between DNASE1L3 and RCC inhibition. We are gonging to explored the mechanism underlying the relationship between DNASEL1L3 and RCC. Methods: RNA sequencing data for RCC tissue and peritumoral tissue were downloaded from The Cancer Genome Atlas database and analyzed. The expression levels of DNASE1L3 in RCC and normal samples were verified using the Gene Expression Omnibus (GEO) database, Human Protein Atlas database and western blotting. The role and potential mechanism of DNASE1L3 were investigated by analysis of immune-related databases and wound healing, invasion, cell counting kit 8 and immunofluorescence assays. Results: We revealed that DNASE1L3 expression was downregulated in RCC group compared with control group [The Cancer Genome Atlas (TCGA): 7.98 vs. 10.87, P<0.001]. Meanwhile, DNASE1L3 expression correlated with the clinical characteristics of patients. Patients with low DNASE1L3 expression had worse survival (P<0.001) and larger (r=-0.32, P<0.001) and heavier tumors (r=-0.17, P<0.001). DNASE1L3 overexpression inhibited the proliferation (786-O: 0.135±0.014 vs. 0.322±0.027, P<0.001) and invasion (786-O: 1,479±134 vs. 832±67, P<0.05) of RCC cells. The expression of DNASE1L3 was significantly correlated with the tumor immune microenvironment and drug sensitivity in ccRCC. Moreover, the level of the key phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway protein P-AKT was decreased in the group of cells transfected with DNASE1L3. Conclusions: This study strongly suggest that DNASE1L3 may be a promising potential biomarker for the diagnosis and treatment of ccRCC patients.

Evaluation of Small Molecules in Blank EDTA Plasma Tubes and Optimization of Metabolomic Workflow for Biomarker Studies Using Plasma Samples.

As the first step of metabolomic analysis in biomarker identification studies, various types of blood collection tubes are used in clinical practice. However, little attention is paid to potential contamination caused by the blank tube itself. Here, we evaluated small molecules in blank EDTA plasma tubes through LC-MS-based untargeted metabolomic analysis and identified small molecules with markedly varied levels among different production batches or specifications. Our data demonstrate possible contamination and data interference caused by blank EDTA plasma tubes when employing large clinical cohorts for biomarker identification. Therefore, we propose a workflow of filtering metabolites in blank tubes prior to statistical analysis to improve the fidelity of biomarker identification.

Genetic basis analysis of key Loci in 23 Yannong series wheat cultivars/lines.

Fungal diseases, drought, pre-harvest sprouting (PHS) and other biotic and abiotic stresses have seriously affected the quality and yield in wheat production. Identifying related genes/loci in released cultivars/lines can provide reference information and theoretical basis for wheat improvement. Yannong series wheat cultivars/lines have distinctive characteristics in wheat cultivars and play an important role in genetic improvement and production of Chinese wheat production system. To dissect their genetic basis of the stress-resistant traits, in this study, 23 representative Yannong series wheat cultivars/lines were tested by 58 molecular markers for 40 genes related to adaptability, disease resistance and stress tolerance to clarify the genetic composition of the key loci. The results showed that most of the tested wheat accessions carried dwarfing genes RhtB1b/RhtD1b/Rht8 and recessive vernalization genes vrn-A1/vrn-B1/vrn-D1/vrn-B3. It was also consistent with the phenotypic traits of tested Yannong series wheat which were dwarf and winter or semi winter wheat. In addition, the overall level of seedling powdery mildew resistance in 23 Yannong wheat cultivars/lines was moderate or inadequate. Eleven accessions carried none of the tested Pm genes and twelve accessions carried Pm2, Pm6, Pm42 and Pm52 singly or in combination. Then, 23 wheat cultivars/lines were also tested by 17 diagnostic markers for 14 Yr genes. The results showed that 16 wheat cultivars/lines were likely to carry one or more of tested Yr genes, whereas Yannong 15, Yannong 17, Yannong 23, Yannong 24, Yannong 377, Yannong 572 and Yannong 999 carried none of the tested Yr genes. Moreover, in our study, nine markers for four genes related to drought tolerance and PHS were used to evaluate the stress tolerance of the 23 wheat cultivars/lines. The results indicated that all 23 wheat cultivars/lines carried drought resistance genes Ta-Dreb1/TaCRT-D, indicating that they had the drought resistance to the extent. Except for Yannong 30, Yannong 377, Yannong 390, Yannong 745 and Yannong 1766, other wheat cultivars/lines carried one to three elite PHS-resistant alleles Vp-1Bc/Vp-1Bf/TaAFP-1Bb.

Metabolic detection of malignant brain gliomas through plasma lipidomic analysis and support vector machine-based machine learning.

BACKGROUND: Most malignant brain gliomas (MBGs) are associated with dismal outcomes, mainly due to their late diagnosis. Current diagnostic methods for MBGs are based on imaging and histological examination, which limits their early detection. Here, we aimed to identify reliable plasma lipid biomarkers for non-invasive diagnosis for MBGs. METHODS: Untargeted lipidomic analysis was firstly performed using a discovery cohort (n=107). The data were processed by a support vector machine (SVM)-based discriminating model to retrieve a panel of candidate biomarkers. Then, a targeted quantification method was developed, and the SVM-based diagnostic model was constructed using a training cohort (n=750) and tested using a test cohort (n=225). Finally, the performance of the diagnostic model was further evaluated in an independent validation cohort (n=920) enrolled from multiple medical centers. FINDINGS: A panel of 11 plasma lipids was identified as candidate biomarkers with an accuracy of 0.999. The diagnostic model developed achieved a high performance in distinguishing MBGs patients from normal controls with an area under the receiver-operating characteristic curve (AUC) of 0.9877 and 0.9869 in the training and test cohorts, respectively. In the validation cohort, the 11 lipid panel still achieved an accuracy of 0.9641 and an AUC of 0.9866. INTERPRETATION: The present study demonstrates the applicability and robustness of utilizing a machine learning algorithm to analyze lipidomic data for efficient and reliable biomarker screening. The 11 lipid biomarkers show great potential for the non-invasive diagnosis of MBGs with high throughput. FUNDING: A full list of funding bodies that contributed to this study can be found in the Acknowledgments section.

HNF4A-AS1-encoded small peptide promotes self-renewal and aggressiveness of neuroblastoma stem cells via eEF1A1-repressed SMAD4 transactivation.

Cancer stem cells play crucial roles in tumorigenesis and aggressiveness, while regulatory mechanisms in neuroblastoma (NB), a pediatric extracranial malignancy with highest incidence, are still unknown. Herein, a small 51-amino acid peptide (sPEP1) encoded by hepatocyte nuclear factor 4 alpha antisense RNA 1 (HNF4A-AS1) was identified in tumor tissues and cells, which facilitated self-renewal and aggressiveness of NB stem cells. MiRNA-409-5p interacted with HNF4A-AS1 to facilitate sPEP1 translation via recruiting eukaryotic translation initiation factor 3 subunit G, while sPEP1 repressed serum deprivation-induced senescence and promoted sphere formation, growth, or metastasis of NB stem cells. Mechanistically, sPEP1 directly interacted with eukaryotic translation elongation factor 1 alpha 1 (eEF1A1) to facilitate its binding to SMAD family member 4 (SMAD4), resulting in repression of SMAD4 transactivation and transcriptional upregulation of stem cell genes associated with tumor progression. Rescue experiments revealed that sPEP1 exerted oncogenic roles via facilitating physical interaction between eEF1A1 and SMAD4. Notably, knockdown of sPEP1 significantly repressed the self-renewal and metastasis of NB stem cells in vivo. High sPEP1 or eEF1A1 levels in clinical NB tissues were linked to poor patients' survival. These findings suggest that HNF4A-AS1-encoded sPEP1 promotes self-renewal and aggressive features of NB stem cells by eEF1A1-repressed SMAD4 transactivation.

Metabolic detection and systems analyses of pancreatic ductal adenocarcinoma through machine learning, lipidomics, and multi-omics.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, characterized by rapid progression, metastasis, and difficulty in diagnosis. However, there are no effective liquid-based testing methods available for PDAC detection. Here we introduce a minimally invasive approach that uses machine learning (ML) and lipidomics to detect PDAC. Through greedy algorithm and mass spectrum feature selection, we optimized 17 characteristic metabolites as detection features and developed a liquid chromatography-mass spectrometry-based targeted assay. In this study, 1033 patients with PDAC at various stages were examined. This approach has achieved 86.74% accuracy with an area under curve (AUC) of 0.9351 in the large external validation cohort and 85.00% accuracy with 0.9389 AUC in the prospective clinical cohort. Accordingly, single-cell sequencing, proteomics, and mass spectrometry imaging were applied and revealed notable alterations of selected lipids in PDAC tissues. We propose that the ML-aided lipidomics approach be used for early detection of PDAC.

Identification of diagnostic markers and lipid dysregulation in oesophageal squamous cell carcinoma through lipidomic analysis and machine learning.

BACKGROUND: Oesophageal cancer (EC) ranks high in both morbidity and mortality. A non-invasive and high-sensitivity diagnostic approach is necessary to improve the prognosis of EC patients. METHODS: A total of 525 serum samples were subjected to lipidomic analysis. We combined serum lipidomics and machine-learning algorithms to select important metabolite features for the detection of oesophageal squamous cell carcinoma (ESCC), the major subtype of EC in developing countries. A diagnostic model using a panel of selected features was developed and evaluated. Integrative analyses of tissue transcriptome and serum lipidome were conducted to reveal the underlying mechanism of lipid dysregulation. RESULTS: Our optimised diagnostic model with a panel of 12 lipid biomarkers together with age and gender reaches a sensitivity of 90.7%, 91.3% and 90.7% and an area under receiver-operating characteristic curve of 0.958, 0.966 and 0.818 in detecting ESCC for the training cohort, validation cohort and independent validation cohort, respectively. Integrative analysis revealed matched variation trend of genes encoding key enzymes in lipid metabolism. CONCLUSIONS: We have identified a panel of 12 lipid biomarkers for diagnostic modelling and potential mechanisms of lipid dysregulation in the serum of ESCC patients. This is a reliable, rapid and non-invasive tumour-diagnostic approach for clinical application.

HNF4A-AS1/hnRNPU/CTCF axis as a therapeutic target for aerobic glycolysis and neuroblastoma progression.

BACKGROUND: Aerobic glycolysis is a hallmark of metabolic reprogramming that contributes to tumor progression. However, the mechanisms regulating expression of glycolytic genes in neuroblastoma (NB), the most common extracranial solid tumor in childhood, still remain elusive. METHODS: Crucial transcriptional regulators and their downstream glycolytic genes were identified by integrative analysis of a publicly available expression profiling dataset. In vitro and in vivo assays were undertaken to explore the biological effects and underlying mechanisms of transcriptional regulators in NB cells. Survival analysis was performed by using Kaplan-Meier method and log-rank test. RESULTS: Hepatocyte nuclear factor 4 alpha (HNF4A) and its derived long noncoding RNA (HNF4A-AS1) promoted aerobic glycolysis and NB progression. Gain- and loss-of-function studies indicated that HNF4A and HNF4A-AS1 facilitated the glycolysis process, glucose uptake, lactate production, and ATP levels of NB cells. Mechanistically, transcription factor HNF4A increased the expression of hexokinase 2 (HK2) and solute carrier family 2 member 1 (SLC2A1), while HNF4A-AS1 bound to heterogeneous nuclear ribonucleoprotein U (hnRNPU) to facilitate its interaction with CCCTC-binding factor (CTCF), resulting in transactivation of CTCF and transcriptional alteration of HNF4A and other genes associated with tumor progression. Administration of a small peptide blocking HNF4A-AS1-hnRNPU interaction or lentivirus-mediated short hairpin RNA targeting HNF4A-AS1 significantly suppressed aerobic glycolysis, tumorigenesis, and aggressiveness of NB cells. In clinical NB cases, high expression of HNF4A-AS1, hnRNPU, CTCF, or HNF4A was associated with poor survival of patients. CONCLUSIONS: These findings suggest that therapeutic targeting of HNF4A-AS1/hnRNPU/CTCF axis inhibits aerobic glycolysis and NB progression.

Therapeutic targeting of YY1/MZF1 axis by MZF1-uPEP inhibits aerobic glycolysis and neuroblastoma progression.

As a hallmark of metabolic reprogramming, aerobic glycolysis contributes to tumorigenesis and aggressiveness. However, the mechanisms and therapeutic strategies regulating aerobic glycolysis in neuroblastoma (NB), one of leading causes of cancer-related death in childhood, still remain elusive. Methods: Transcriptional regulators and their downstream glycolytic genes were identified by a comprehensive screening of publicly available datasets. Dual-luciferase, chromatin immunoprecipitation, real-time quantitative RT-PCR, western blot, gene over-expression or silencing, co-immunoprecipitation, mass spectrometry, peptide pull-down assay, sucrose gradient sedimentation, seahorse extracellular flux, MTT colorimetric, soft agar, matrigel invasion, and nude mice assays were undertaken to explore the biological effects and underlying mechanisms of transcriptional regulators in NB cells. Survival analysis was performed by using log-rank test and Cox regression assay. Results: Transcription factor myeloid zinc finger 1 (MZF1) was identified as an independent prognostic factor (hazard ratio=2.330, 95% confidence interval=1.021 to 3.317), and facilitated glycolysis process through increasing expression of hexokinase 2 (HK2) and phosphoglycerate kinase 1 (PGK1). Meanwhile, a 21-amino acid peptide encoded by upstream open reading frame of MZF1, termed as MZF1-uPEP, bound to zinc finger domain of Yin Yang 1 (YY1), resulting in repressed transactivation of YY1 and decreased transcription of MZF1 and downstream genes HK2 and PGK1. Administration of a cell-penetrating MZF1-uPEP or lentivirus over-expressing MZF1-uPEP inhibited the aerobic glycolysis, tumorigenesis and aggressiveness of NB cells. In clinical NB cases, low expression of MZF1-uPEP or high expression of MZF1, YY1, HK2, or PGK1 was associated with poor survival of patients. Conclusions: These results indicate that therapeutic targeting of YY1/MZF1 axis by MZF1-uPEP inhibits aerobic glycolysis and NB progression.

Long Noncoding RNA NHEG1 Drives ß-Catenin Transactivation and Neuroblastoma Progression through Interacting with DDX5.

Recent studies suggest that long noncoding RNAs (lncRNAs) play essential roles in tumor progression. However, the functional roles and underlying mechanisms of lncRNAs in neuroblastoma (NB), the most common malignant solid tumor in pediatric population, still remain elusive. Herein, through integrating analysis of a public RNA sequencing dataset, neuroblastoma highly expressed 1 (NHEG1) was identified as a risk-associated lncRNA, contributing to an unfavorable outcome of NB. Depletion of NHEG1 led to facilitated differentiation and decreased growth and aggressiveness of NB cells. Mechanistically, NHEG1 bound to and stabilized DEAD-box helicase 5 (DDX5) protein through repressing proteasome-mediated degradation, resulting in ß-catenin transactivation that altered target gene expression associated with NB progression. We further determined a lymphoid enhancer binding factor 1 (LEF1)/transcription factor 7-like 2 (TCF7L2)/NHEG1/DDX5/ß-catenin axis with a positive feedback loop and demonstrated that NHEG1 harbored oncogenic properties via its interplay with DDX5. Administration of small interfering RNAs against NHEG1 or DDX5 reduced tumor growth and prolonged survival of nude mice bearing xenografts. High NHEG1 or DDX5 expression was associated with poor survival of NB patients. These results indicate that lncRNA NHEG1 exhibits oncogenic activity that affects NB progression via stabilizing the DDX5 protein, which might serve as a potential therapeutic target for NB.

Therapeutic targeting of circ-CUX1/EWSR1/MAZ axis inhibits glycolysis and neuroblastoma progression.

Aerobic glycolysis is a hallmark of metabolic reprogramming in tumor progression. However, the mechanisms regulating glycolytic gene expression remain elusive in neuroblastoma (NB), the most common extracranial malignancy in childhood. Herein, we identify that CUT-like homeobox 1 (CUX1) and CUX1-generated circular RNA (circ-CUX1) contribute to aerobic glycolysis and NB progression. Mechanistically, p110 CUX1, a transcription factor generated by proteolytic processing of p200 CUX1, promotes the expression of enolase 1, glucose-6-phosphate isomerase, and phosphoglycerate kinase 1, while circ-CUX1 binds to EWS RNA-binding protein 1 (EWSR1) to facilitate its interaction with MYC-associated zinc finger protein (MAZ), resulting in transactivation of MAZ and transcriptional alteration of CUX1 and other genes associated with tumor progression. Administration of an inhibitory peptide blocking circ-CUX1-EWSR1 interaction or lentivirus mediating circ-CUX1 knockdown suppresses aerobic glycolysis, growth, and aggressiveness of NB cells. In clinical NB cases, CUX1 is an independent prognostic factor for unfavorable outcome, and patients with high circ-CUX1 expression have lower survival probability. These results indicate circ-CUX1/EWSR1/MAZ axis as a therapeutic target for aerobic glycolysis and NB progression.

Therapeutic Targeting of MZF1-AS1/PARP1/E2F1 Axis Inhibits Proline Synthesis and Neuroblastoma Progression.

Proline synthesis plays an important role in the metabolic reprogramming that contributes to tumor progression. However, the mechanisms regulating expression of proline synthetic genes in neuroblastoma (NB) remain elusive. Herein, through integrative screening of a public dataset and amino acid profiling analysis, myeloid zinc finger 1 (MZF1) and MZF1 antisense RNA 1 (MZF1-AS1) are identified as transcriptional regulators of proline synthesis and NB progression. Mechanistically, transcription factor MZF1 promotes the expression of aldehyde dehydrogenase 18 family member A1 and pyrroline-5-carboxylate reductase 1, while proline facilitates the aggressiveness of NB cells. In addition, MZF1-AS1 binds poly(ADP-ribose) polymerase 1 (PARP1) to facilitate its interaction with E2F transcription factor 1 (E2F1), resulting in transactivation of E2F1 and upregulation of MZF1 and other oncogenic genes associated with tumor progression. Administration of a small peptide blocking MZF1-AS1-PARP1 interaction or lentivirus-mediated short hairpin RNA targeting MZF1-AS1 suppresses the proline synthesis, tumorigenesis, and aggressiveness of NB cells. In clinical NB cases, high expression of MZF1-AS1, PARP1, E2F1, or MZF1 is associated with poor survival of patients. These results indicate that therapeutic targeting of MZF1-AS1/PARP1/E2F1 axis inhibits proline synthesis and NB progression.

Circular RNA circAGO2 drives cancer progression through facilitating HuR-repressed functions of AGO2-miRNA complexes.

Argonaute 2 (AGO2), the core component of microRNA (miRNA)-induced silencing complex, plays a compelling role in tumorigenesis and aggressiveness. However, the mechanisms regulating the functions of AGO2 in cancer still remain elusive. Herein, we indentify one intronic circular RNA (circRNA) generated from AGO2 gene (circAGO2) as a novel regulator of AGO2-miRNA complexes and cancer progression. CircAGO2 is up-regulated in gastric cancer, colon cancer, prostate cancer, and neuroblastoma, and is associated with poor prognosis of patients. CircAGO2 promotes the growth, invasion, and metastasis of cancer cells in vitro and in vivo. Mechanistic studies reveal that circAGO2 physically interacts with human antigen R (HuR) protein to facilitate its activation and enrichment on the 3'-untranslated region of target genes, resulting in reduction of AGO2 binding and repression of AGO2/miRNA-mediated gene silencing associated with cancer progression. Pre-clinically, administration of lentivirus-mediated short hairpin RNA targeting circAGO2 inhibits the expression of downstream target genes, and suppresses the tumorigenesis and aggressiveness of xenografts in nude mice. In addition, blocking the interaction between circAGO2 and HuR by cell-penetrating inhibitory peptide represses the tumorigenesis and aggressiveness of cancer cells. Taken together, these results indicate that oncogenic circAGO2 drives cancer progression through facilitating HuR-repressed functions of AGO2-miRNA complexes.

Cis-Acting circ-CTNNB1 Promotes ß-Catenin Signaling and Cancer Progression via DDX3-Mediated Transactivation of YY1.

Circular RNAs (circRNA), a subclass of noncoding RNA characterized by covalently closed continuous loops, play emerging roles in tumorigenesis and aggressiveness. However, the functions and underlying mechanisms of circRNA in regulating Wnt/ß-catenin signaling and cancer progression remain elusive. Here, we screen cis-acting circRNA generated by ß-catenin (CTNNB1)/transcription factor 7-like 2 genes and identify one intronic circRNA derived from CTNNB1 (circ-CTNNB1) as a novel driver of cancer progression. Circ-CTNNB1 was predominantly expressed in the nucleus, upregulated in cancer tissues and cell lines, and associated with unfavorable outcomes in patients with cancer. Circ-CTNNB1 promoted ß-catenin activation, growth, invasion, and metastasis in cancer cells. Circ-CTNNB1 bound DEAD-box polypeptide 3 (DDX3) to facilitate its physical interaction with transcription factor Yin Yang 1 (YY1), resulting in the transactivation of YY1 and transcriptional alteration of downstream genes associated with ß-catenin activation and cancer progression. Preclinically, administration of lentivirus-mediated short hairpin RNA targeting circ-CTNNB1 or a cell-penetrating inhibitory peptide blocking the circ-CTNNB1-DDX3 interaction inhibited downstream gene expression, tumorigenesis, and aggressiveness in cancer cells. Taken together, these results demonstrate cis-acting circ-CTNNB1 as a mediator of ß-catenin signaling and cancer progression through DDX3-mediated transactivation of YY1. SIGNIFICANCE: These findings reveal the oncogenic functions of a cis-acting circular RNA in ß-catenin activation and cancer progression, with potential value as a therapeutic target for human cancers.