173 research outputs found
MicroRNA-Mediated Metabolic Shaping of the Tumor Microenvironment
The metabolism of cancer cells is generally very different from what is found in normal counterparts. However, in a tumor mass, the continuous crosstalk and competition for nutrients and oxygen among different cells lead to metabolic alterations, not only in cancer cells, but also in the different stromal and immune cells of the tumor microenvironment (TME), which are highly relevant for tumor progression. MicroRNAs (miRs) are small non-coding RNAs that silence their mRNA targets post-transcriptionally and are involved in numerous physiological cell functions as well as in the adaptation to stress situations. Importantly, miRs can also be released via extracellular vesicles (EVs) and, consequently, take part in the bidirectional communication between tumor and surrounding cells under stress conditions. Certain miRs are abundantly expressed in stromal and immune cells where they can regulate various metabolic pathways by directly suppressing enzymes or transporters as well as by controlling important regulators (such as transcription factors) of metabolic processes. In this review, we discuss how miRs can induce metabolic reprogramming in stromal (fibroblasts and adipocytes) and immune (macrophages and T cells) cells and, in turn, how the biology of the different cells present in the TME is able to change. Finally, we debate the rebound of miR-dependent metabolic alterations on tumor progression and their implications for cancer management
Identification of functional TFAP2A and SP1 binding sites in new TFAP2A-modulated genes
BACKGROUND: Different approaches have been developed to dissect the interplay between transcription factors (TFs) and their cis-acting sequences on DNA in order to identify TF target genes. Here we used a combination of computational and experimental approaches to identify novel direct targets of TFAP2A, a key TF for a variety of physiological and pathological cellular processes. Gene expression profiles of HeLa cells either silenced for TFAP2A by RNA interference or not were previously compared and a set of differentially expressed genes was revealed.
RESULTS: The regulatory regions of 494 TFAP2A-modulated genes were analyzed for the presence of TFAP2A binding sites, employing the canonical TFAP2A Positional Weight Matrix (PWM) reported in Jaspar http://jaspar.genereg.net/. 264 genes containing at least 2 high score TFAP2A binding sites were identified, showing a central role in "Cellular Movement" and "Cellular Development". In an attempt to identify TFs that could cooperate with TFAP2A, a statistically significant enrichment for SP1 binding sites was found for TFAP2A-activated but not repressed genes. The direct binding of TFAP2A or SP1 to a random subset of TFAP2A-modulated genes was demonstrated by Chromatin ImmunoPrecipitation (ChIP) assay and the TFAP2A-driven regulation of DCBLD2/ESDN/CLCP1 gene studied in details.
CONCLUSIONS: We proved that our computational approaches applied to microarray selected genes are valid tools to identify functional TF binding sites in gene regulatory regions as confirmed by experimental validations. In addition, we demonstrated a fine-tuned regulation of DCBLD2/ESDN transcription by TFAP2A
C-reactive protein level predicts mortality in COPD: a systematic review and meta-analysis
The prognostic role of baseline C-reactive protein (CRP) in chronic obstructive pulmonary disease (COPD) is controversial. In order to clarify this issue, we performed a systematic review and meta-analysis to assess the predictive effect of baseline CRP level in COPD patients. 15 eligible articles focusing on late mortality in COPD were included in our study. We performed a random-effects meta-analysis, and assessed heterogeneity and publication bias. We pooled hazard ratio (HR) estimates and their 95% confidence intervals on mortality for the comparison between the study-specific highest category of CRP levelversusthe lowest category. In overall analysis, elevated baseline CRP levels were significantly associated with higher mortality (HR 1.53, 95% CI 1.32â1.77,I2=68.7%, p<0.001). Similar results were observed across subgroups. However, higher mortality risk was reported in studies using a cut-off value of 3â
mg·Lâ1(HR 1.61, 95% CI 1.12â2.30) and in those enrolling an Asiatic population (HR 3.51, 95% CI 1.69â7.31). Our analysis indicates that baseline high CRP level is significantly associated with higher late mortality in patients with COPD. Further prospective controlled studies are needed to confirm these data
microRNA-222 controls neovascularization by regulating signal transducer and activator of transcription 5A expression.
OBJECTIVE: Inflammatory stimuli released into atherosclerotic plaque microenvironment regulate vessel formation by modulating gene expression and translation. microRNAs are a class of short noncoding RNAs, acting as posttranscriptional regulators of protein-coding genes involved in various biological processes, including vascular cell biology. Among them, microRNA-221/222 (miR-221/222) seem to negatively modulate vascular remodeling by targeting different target genes. Here, we investigated their potential contribution to inflammation-mediated neovessel formation.
METHODS AND RESULTS: We used quantitative real-time RT-PCR amplification to analyze expression of 7 microRNAs previously linked to vascular biology, such as miR-17-5p, miR-21, miR-126, miR-210, miR-221, miR-222, and miR-296 and found high levels of expression for all of them in quiescent endothelial cells. However, miR-126, miR-221, miR-222, and miR-296 turned out to be down-modulated in endothelial cells exposed to inflammatory stimuli. Applying a gain-of-function approach, we demonstrated that, among them, only miR-222 was involved in inflammation-mediated vascular remodeling. In addition, we identified signal transducer and activator of transcription 5A (STAT5A) as a bona fide target of miR-222 and observed that miR-222 negatively correlated with STAT5A expression in human endothelial cells from advanced neovascularized atherosclerotic lesions.
CONCLUSIONS: We identified STAT5A as a novel miR-222 target, and this finding opens up new perspectives for treatment of vascular diseases
CyTRANSFINDER: a Cytoscape 3.3 plugin for three-component (TF, gene, miRNA) signal transduction pathway construction
Background: Biological research increasingly relies on network models to study complex phenomena. Signal Transduction Pathways are molecular circuits that model how cells receive, process, and respond to information from the environment providing snapshots of the overall cell dynamics. Most of the attempts to reconstruct signal transduction pathways are limited to single regulator networks including only genes/proteins. However, networks involving a single type of regulator and neglecting transcriptional and post-transcriptional regulations mediated by transcription factors and microRNAs, respectively, may not fully reveal the complex regulatory mechanisms of a cell. We observed a lack of computational instruments supporting explorative analysis on this type of three-component signal transduction pathways. Results: We have developed CyTRANSFINDER, a new Cytoscape plugin able to infer three-component signal transduction pathways based on user defined regulatory patterns and including miRNAs, TFs and genes. Since CyTRANSFINDER has been designed to support exploratory analysis, it does not rely on expression data. To show the potential of the plugin we have applied it in a study of two miRNAs that are particularly relevant in human melanoma progression, miR-146a and miR-214. Conclusions: CyTRANSFINDERsupportsthereconstructionofsmallsignaltransductionpathwaysamonggroupsof genes. Results obtained from its use in a real case study have been analyzed and validated through both literature data and preliminary wet-lab experiments, showing the potential of this tool when performing exploratory analysi
A computational pipeline to identify new potential regulatory motifs in melanoma progression
Molecular biology experiments allow to obtain reliable data about the expression of different classes of molecules involved in several cellular processes. This information is mostly static and does not give much clue about the causal relationships (i.e., regulation) among the different molecules. A typical scenario is the presence of a set of modulated mRNAs (up or down regulated) along with an over expression of one or more small non-coding RNAs molecules like miRNAs. To computationally identify the presence of transcriptional or post-transcriptional regulatory modules between one or more miRNAs and a set of target modulated genes, we propose a computational pipeline designed to integrate data from multiple online data repositories. The pipeline produces a set of three types of putative regulatory motifs involving coding genes, intronic miRNAs, and transcription factors. We used this pipeline to analyze the results of a set of expression experiments on a melanoma cell line that showed an over expression of miR-214 along with the modulation of a set of 73 other genes. The results suggest the presence of 27 putative regulatory modules involving miR-214, NFKB1, SREBPF2, miR-33a and 9 out of the 73 miR-214 modulated genes (ALCAM, POSTN, TFAP2A, ADAM9, NCAM1, SEMA3A, PVRL2, JAG1, EGFR1). As a preliminary experimental validation we focused on 9 out of the 27 identified regulatory modules that involve miR-33a and SREBF2. The results confirm the importance of the predictions obtained with the presented computational approach
miR-214 coordinates melanoma progression by upregulating ALCAM through TFAP2 and miR-148b downmodulation
Malignant melanoma is one of the most aggressive human cancers, but the mechanisms governing its metastatic dissemination are not fully understood. Upregulation of miR-214 and ALCAM and the loss of TFAP2 expression have been implicated in this process, with TFAP2 a direct target of miR-214. Here, we link miR-214 and ALCAM as well as identify a core role for miR-214 in organizing melanoma metastasis. miR-
214 upregulated ALCAM, acting transcriptionally through TFAP2 and also posttranscriptionally through miR-148b (itself controlled by TFAP2), both negative regulators of ALCAM. We also identiïŹed several miR-214âmediated prometastatic functions directly promoted by ALCAM. Silencing ALCAM in miR-214âoverexpressing melanoma cells reduced cell migration and invasion without affecting growth or anoikisin vitro, and it also impaired extravasation and metastasis formation in vivo. Conversely, cell migration and extravasation was reduced in miR-214âoverexpressing cells by upregulation of either miR 148b or TFAP2. These ïŹndings were consistent with patterns of expression of miR-214, ALCAM, and miR-148b in human
melanoma specimens. Overall, our results deïŹne a pathway involving miR-214, miR-148b, TFAP2, and ALCAM that is critical for establishing distant metastases in melanoma
AP-2α regulates migration of GN-11 neurons via a specific genetic programme involving the Axl receptor tyrosine kinase
<p>Abstract</p> <p>Background</p> <p>Neuronal migration is a crucial process that allows neurons to reach their correct target location to allow the nervous system to function properly. AP-2α is a transcription factor essential for neural crest cell migration and its mutation results in apoptosis within this cell population, as demonstrated by genetic models.</p> <p>Results</p> <p>We down-modulated AP-2α expression in GN-11 neurons by RNA interference and observe reduced neuron migration following the activation of a specific genetic programme including the Adhesion Related Kinase (<it>Axl</it>) gene. We prove that <it>Axl </it>is able to coordinate migration per se and by ChIP and promoter analysis we observe that its transcription is directly driven by AP-2α via the binding to one or more functional AP-2α binding sites present in its regulatory region. Analysis of migration in AP-2α null mouse embryo fibroblasts also reveals an essential role for AP-2α in cell movement via the activation of a distinct genetic programme.</p> <p>Conclusion</p> <p>We show that AP-2α plays an essential role in cell movement via the activation of cell-specific genetic programmes. Moreover, we demonstrate that the AP-2α regulated gene <it>Axl </it>is an essential player in GN-11 neuron migration.</p
Expression of AP-2a, AP-2g and ESDN in primary melanomas: Correlation with histopathological features and potential prognostic value
Baseline and postoperative C-reactive protein levels predict mortality in operable lung cancer.
Background Higher blood levels of C-reactive protein (CRP) have been associated with shorter survival in patients with cardiovascular, chronic obstructive pulmonary disease and cancer. We investigated the impact of baseline and postoperative CRP levels on survival of patients with operable lung cancer (LC). Patients and methods CRP values at baseline (CRP0) and 3 days after surgery (CRP3) were measured in a consecutive series of 1750 LC patients who underwent complete resection between 2003 and 2015. Patients were classified as having 0 (N = 593), 1 (N = 658) or 2 (N = 553) risk factors: CRP0 and/or CRP3 values above the respective median value. The effect of higher CRP was evaluated by KaplanâMeier mortality curves and adjusted hazard ratio (HR) with 95% confidence interval (CI), by fitting Cox proportional hazards models. Results Cumulative proportions of 5-year survival were 67% for 0 risk factors, 58% for 1 risk factor and 41% for 2 risk factors (P < 0.0001). The overall 5-year mortality risk was significantly higher in patients with 1 risk factor (adjusted hazard ratio [aHR] 1.43 [95% CI 1.14â1.79]), or 2 risk factors (aHR 2.49 [95% CI 1.99â3.11]). A significant impact on survival was observed in each tumour-node-metastasis stage group, and in the subset of non-smokers. Postoperative 30-day mortality was significantly higher in patients with 2 risk factors only (aHR 2.2% versus 0.6%, p < 0.0475). Conclusions Baseline and postoperative CRP levels predict immediate and long-term mortality in all stages of operable lung cancer. Patients with higher CRP levels could be candidate to randomised adjuvant trials with anti-inflammatory agents
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