scholarly journals A Novel Positive Feedback Loop Between NTSR1 and Wnt/β-Catenin Contributes to Tumor Growth of Glioblastoma

2017 ◽  
Vol 43 (5) ◽  
pp. 2133-2142 ◽  
Author(s):  
Hualiang Xiao ◽  
Ying Zeng ◽  
Qiushi Wang ◽  
Shirong Wei ◽  
Xiangfeng Zhu
Keyword(s):  
Tumor Growth ◽  
Cancer Progression ◽  
Positive Feedback ◽  
Feedback Loop ◽  
Mitogen Activated Protein Kinase ◽  
Glioblastoma Cells ◽  
Positive Feedback Loop ◽  
Pharmacological Inhibition ◽  
Wnt Proteins

Background/Aims: Neurotensin (NTS), an intestinal hormone, is profoundly implicated in cancer progression through binding its primary receptor NTSR1. The conserved Wnt/β-Catenin pathway regulates cell proliferation and differentiation via activation of the β-catenin/T-cell factor (TCF) complex and subsequent modulation of a set of target genes. In this study, we aimed to uncover the potential connection between NTS/NTSR1 signaling and Wnt/β-Catenin pathway. Methods: Genetic silencing, pharmacological inhibition and gain-of-function studies as well as bioinformatic analysis were performed to uncover the link between NTS/ NTSR1 signaling and Wnt/β-Catenin pathway. Two inhibitors were used in vivo to evaluate the efficiency of targeting NTS/NTSR1 signaling or Wnt/β-Catenin pathway. Results: We found that NTS/NTSR1 induced the activation of mitogen-activated protein kinase (MAPK) and the NF-κB pathway, which further promoted the expression of Wnt proteins, including Wnt1, Wnt3a and Wnt5a. Meanwhile, the mRNA and protein expression levels of NTSR1 were increased by the Wnt pathway activator Wnt3a and decreased by the Wnt inhibitor iCRT3 in glioblastoma cells. Furthermore, pharmacological inhibition of NTS/NTSR1 or Wnt/β-Catenin signaling suppressed tumor growth in vitro and in vivo. Conclusion: These results reveal a positive feedback loop between NTS/NTSR1 and Wnt/β-Catenin signaling in glioblastoma cells that might be important for tumor development and provide potential therapeutic targets for glioblastoma.

scholarly journals A Positive Feedback Loop of lncRNA MIR31HG-miR-361-3p -YY1 Accelerates Colorectal Cancer Progression Through Modulating Proliferation, Angiogenesis, and Glycolysis

2021 ◽  
Vol 11 ◽  
Author(s):  
Tao Guo ◽  
Defeng Liu ◽  
Shihao Peng ◽  
Meng Wang ◽  
Yangyang Li
Keyword(s):  
Colorectal Cancer ◽  
Cancer Progression ◽  
Positive Feedback ◽  
Feedback Loop ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Positive Feedback Loop ◽  
Related Proteins

BackgroundColorectal cancer (CRC) is a common malignant tumor with high metastatic and recurrent rates. This study probes the effect and mechanism of long non-coding RNA MIR31HG on the progression of CRC cells.Materials and MethodsQuantitative real-time PCR (qRT-PCR) was used to analyze the expression of MIR31HG and miR-361-3p in CRC tissues and normal tissues. Gain- or loss-of-function assays were conducted to examine the roles of MIR31HG, miR-361-3p and YY1 transcription factor (YY1) in the CRC progression. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and colony formation experiment were conducted to test CRC cell proliferation. CRC cell invasion was determined by Transwell assay. The glucose detection kit and lactic acid detection kit were utilized to monitor the levels of glucose and lactate in CRC cells. The glycolysis level in CRC cells was examined by the glycolytic stress experiment. Western blot was performed to compare the expression of glycolysis-related proteins (PKM2, GLUT1 and HK2) and angiogenesis-related proteins (including VEGFA, ANGPT1, HIF1A and TIMP1) in HUVECs. The binding relationships between MIR31HG and miR-361-3p, miR-361-3p and YY1 were evaluated by the dual-luciferase reporter assay and RNA immunoprecipitation (RIP).ResultsMIR31HG was up-regulated in CRC tissues and was associated with poorer prognosis of CRC patients. The in-vitro and in-vivo experiments confirmed that overexpressing MIR31HG heightened the proliferation, growth, invasion, glycolysis and lung metastasis of CRC cells as well as the angiogenesis of HUVECs. In addition, MIR3HG overexpression promoted YY1 mRNA and protein level, and forced overexpression of YY1 enhanced MIR31HG level. Overexpressing YY1 reversed the tumor-suppressive effect mediated by MIR31HG knockdown. miR-361-3p, which was inhibited by MIR31HG overexpression, repressed the malignant behaviors of CRC cells. miR-361-3p-mediated anti-tumor effects were mostly reversed by upregulating MIR31HG. Further mechanism studies illustrated that miR-361-3p targeted and negatively regulated the expression of YY1.ConclusionThis study reveals that MIR31HG functions as an oncogenic gene in CRC via forming a positive feedback loop of MIR31HG-miR-361-3p-YY1.

scholarly journals CDK13 upregulation-induced formation of the positive feedback loop among circCDK13, miR-212-5p/miR-449a and E2F5 contributes to prostate carcinogenesis

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Jin-Chun Qi ◽  
Zhan Yang ◽  
Tao Lin ◽  
Long Ma ◽  
Ya-Xuan Wang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Transcriptional Activation ◽  
Positive Feedback ◽  
Feedback Loop ◽  
Biological Effects ◽  
Therapeutic Benefit ◽  
Loss Of Function ◽  
Positive Feedback Loop

Abstract Background Both E2F transcription factor and cyclin-dependent kinases (CDKs), which increase or decrease E2F activity by phosphorylating E2F or its partner, are involved in the control of cell proliferation, and some circRNAs and miRNAs regulate the expression of E2F and CDKs. However, little is known about whether dysregulation among E2Fs, CDKs, circRNAs and miRNAs occurs in human PCa. Methods The expression levels of CDK13 in PCa tissues and different cell lines were determined by quantitative real-time PCR and Western blot analysis. In vitro and in vivo assays were preformed to explore the biological effects of CDK13 in PCa cells. Co-immunoprecipitation anlysis coupled with mass spectrometry was used to identify E2F5 interaction with CDK13. A CRISPR-Cas9 complex was used to activate endogenous CDK13 and circCDK13 expression. Furthermore, the mechanism of circCDK13 was investigated by using loss-of-function and gain-of-function assays in vitro and in vivo. Results Here we show that CDK13 is significantly upregulated in human PCa tissues. CDK13 depletion and overexpression in PCa cells decrease and increase, respectively, cell proliferation, and the pro-proliferation effect of CDK13 is strengthened by its interaction with E2F5. Mechanistically, transcriptional activation of endogenous CDK13, but not the forced expression of CDK13 by its expression vector, remarkably promotes E2F5 protein expression by facilitating circCDK13 formation. Further, the upregulation of E2F5 enhances CDK13 transcription and promotes circCDK13 biogenesis, which in turn sponges miR-212-5p/449a and thus relieves their repression of the E2F5 expression, subsequently leading to the upregulation of E2F5 expression and PCa cell proliferation. Conclusions These findings suggest that CDK13 upregulation-induced formation of the positive feedback loop among circCDK13, miR-212-5p/miR-449a and E2F5 is responsible for PCa development. Targeting this newly identified regulatory axis may provide therapeutic benefit against PCa progression and drug resistance.

scholarly journals Interaction of Apoptotic Cells with Macrophages Upregulates COX-2/PGE2and HGF Expression via a Positive Feedback Loop

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Ji Yeon Byun ◽  
Young-So Youn ◽  
Ye-Ji Lee ◽  
Youn-Hee Choi ◽  
So-Yeon Woo ◽  
...  
Keyword(s):  
Positive Feedback ◽  
Tissue Repair ◽  
Feedback Loop ◽  
Apoptotic Cell ◽  
Raw 264.7 Cells ◽  
Apoptotic Cells ◽  
Positive Feedback Loop ◽  
Cox 2

Recognition of apoptotic cells by macrophages is crucial for resolution of inflammation, immune tolerance, and tissue repair. Cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) and hepatocyte growth factor (HGF) play important roles in the tissue repair process. We investigated the characteristics of macrophage COX-2 and PGE2expression mediated by apoptotic cells and then determined how macrophages exposed to apoptotic cellsin vitroandin vivoorchestrate the interaction between COX-2/PGE2and HGF signaling pathways. Exposure of RAW 264.7 cells and primary peritoneal macrophages to apoptotic cells resulted in induction of COX-2 and PGE2. The COX-2 inhibitor NS-398 suppressed apoptotic cell-induced PGE2production. Both NS-398 and COX-2-siRNA, as well as the PGE2receptor EP2 antagonist, blocked HGF expression in response to apoptotic cells. In addition, the HGF receptor antagonist suppressed increases in COX-2 and PGE2induction. Thein vivorelevance of the interaction between the COX-2/PGE2and HGF pathways through a positive feedback loop was shown in cultured alveolar macrophages followingin vivoexposure of bleomycin-stimulated lungs to apoptotic cells. Our results demonstrate that upregulation of the COX-2/PGE2and HGF in macrophages following exposure to apoptotic cells represents a mechanism for mediating the anti-inflammatory and antifibrotic consequences of apoptotic cell recognition.

scholarly journals Floral organ abscission is regulated by a positive feedback loop

2015 ◽  
Vol 112 (9) ◽  
pp. 2906-2911 ◽  
Author(s):  
O. Rahul Patharkar ◽  
John C. Walker
Keyword(s):  
Map Kinase ◽  
Positive Feedback ◽  
Regulatory Networks ◽  
Feedback Loop ◽  
Dynamic Range ◽  
Floral Organ ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Positive Feedback Loop ◽  
Genetic Components

Abscission is the process by which plants shed unwanted organs, either as part of a natural developmental program or in response to environmental stimuli. Studies in Arabidopsis thaliana have elucidated a number of the genetic components that regulate abscission of floral organs, including a pair of related receptor-like protein kinases, HAESA and HAESA-like 2 (HAE/HSL2) that regulate a MAP kinase cascade that is required for abscission. HAE is transcriptionally up-regulated in the floral abscission zone just before cell separation. Here, we identify AGAMOUS-like 15 (AGL15; a MADS-domain transcription factor) as a putative regulator of HAE expression. Overexpression of AGL15 results in decreased expression of HAE as well as a delayed abscission phenotype. Chromatin immunoprecipitation experiments indicate that AGL15 binds the HAE promoter in floral receptacles. AGL15 is then differentially phosphorylated through development in floral receptacles in a MITOGEN-ACTIVATED PROTEIN KINASE KINASE 4/5-dependent manner. MAP kinase phosphorylation of AGL15 is necessary for full HAE expression, thus completing a positive feedback loop controlling HAE expression. Together, the network components in this positive feedback loop constitute an emergent property that regulates the large dynamic range of gene expression (27-fold increase in HAE) observed in flowers when the abscission program is initiated. This study helps define the mechanisms and regulatory networks involved in a receptor-mediated signaling pathway that controls floral organ abscission.

scholarly journals The Establishment of CDK9/ RNA PolII/H3K4me3/DNA Methylation Feedback Promotes HOTAIR Expression by RNA Elongation Enhancement in Cancer

2019 ◽  
Author(s):  
Chi Hin Wong ◽  
Chi Han Li ◽  
Qifang He ◽  
Joanna Hung Man Tong ◽  
Ka-Fai To ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Cancer Progression ◽  
Positive Feedback ◽  
Feedback Loop ◽  
Transcription Elongation ◽  
Underlying Mechanism ◽  
Transcriptional Elongation ◽  
Gene Body ◽  
Gene Body Methylation ◽  
Positive Feedback Loop

SUMMARYLong non-coding RNA HOX Transcript Antisense RNA (HOTAIR) is overexpressed in multiple cancers with diverse genetic profiles, which heavily contributed to cancer progression. However, the underlying mechanism leading to HOTAIR deregulation is largely unexplored. Here, we revealed that gene body methylation promoted HOTAIR expression through enhancing the transcription elongation process in cancer. We linked up the aberrant gene body histone and DNA methylation in promoting transcription elongation via phosphorylation of Polymerase II Ser 2 by CDK7-CDK9, and elucidated the mechanism of a positive feedback loop involving CDK7, MLL1 and DNMT3A in promoting gene body methylation and overexpressing HOTAIR. To our knowledge, this is the first time to demonstrate that a positive feedback loop that involved CDK9-mediated phosphorylation of PolII and histone and gene body methylation induced robust transcriptional elongation, which heavily contributed to the upregulation of oncogenic lncRNA in cancer.

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