EGF decreases the abundance of microRNAs that restrain oncogenic transription factors
ABSTRACT: Epidermal growth factor (EGF) stimulates cells by launching gene expression programs that are frequently deregulated in cancer. MicroRNAs, which attenuate gene expression by binding complementary regions in messenger RNAs, are broadly implicated in cancer. Using genome-wide approaches, we showed that EGF stimulation initiates a coordinated transcriptional program of microRNAs and transcription factors. The earliest event involved a decrease in the abundance of a subset of 23 microRNAs. This step permitted rapid induction of oncogenic transcription factors, such as c-FOS, encoded by immediate early genes. In line with roles as suppressors of EGF receptor (EGFR) signaling, we report that the abundance of this early subset of microRNAs is decreased in breast and in brain tumors driven by the EGFR or the closely related HER2. These findings identify specific microRNAs as attenuators of growth factor signaling and oncogenesis 24 conditions: time course of 8 hours of HeLa and MCF10A cells after EGF or SERUM stimulation
Project description:The EGF-receptor (EGFR) is amplified and mutated in glioblastoma (GBM) where its common mutation, (∆EGFR, also called EGFRvIII) has a variety of activities that promote growth and inhibit death, thereby conferring a strong tumor-enhancing effect. This range of activities suggested to us that ∆EGFR might exert its influence through pleiotropic effectors and we hypothesized that microRNAs (miRs) might serve such a function. To test this, we determined the miR profiles of GBM cells with activated wild type EGFR (wtEGFR) and mutant EGFR (∆EGFR) to cells with non-activated EGFR or kinase dead ∆EGFR. To identify miRs regulated by EGFR, RNA from 2 different glioma cell lines (U87 and U373) were hybridized to miR expression arrays and analyzed. Each cell type was engineered to express wild type EGFR (wtEGFR), dead kinase ∆EGFR (DK) or ∆EGFR at elevated levels similar to those observed in primary glioblastomas displaying EGFR overexpression. Parental cells expressing endogenous EGFR and wtEGFR cells stimulated with EGF for 1hr were also included in the analyses.
Project description:In order to detect the microRNA expression profile of in vitro generated dendritic cells , purified monocytes from PBMCs were used as dendritic cell (DCs) precursors and were cultured in medium with cocktail for differentiation and maturation to immature dendritic cells (iDCs) and mature dendritic cells (mDCs). microRNA samples were isolated from precursor, iDCs and mDCs and used for microarray-based microRNAs expression profiles. To generate enough amount of immature DC (iDCs) and mature DCs (mDCs), monocytes were differentiated with GM-CSF and rhIL-4 for 2 days and maturated in the presence of TNF-α, IL-1β, IL-6 and PGE2 for another 2 days. With the anticipation to insight developmental-stage-specific microRNAs with potential functions related to monocyte derived DCs, global microRNAs expression profiling was set using microarray technology.microRNA expression profiles were performed in triplicate independent experiments starting for 3 groups of precursor, iDC and mDC generated from different blood donors.
Project description:microRNA dysregulation is a common feature of cancer cells, but the complex roles of microRNAs in cancer are not fully elucidated. Here we used functional genomics to identify oncogenic microRNAs in non-small cell lung cancer and to evaluate their impact on response to EGFR targeting therapy. Our data demonstrate that microRNAs with an AAGUGC-motif in their seed-sequence increase both cancer cell proliferation and sensitivity to EGFR inhibitors. Global transcriptomics, proteomics and target prediction resulted in the identification of several tumor suppressors involved in the G1/S transition as targets of AAGUGC-microRNAs. The clinical implications of our findings were evaluated by analysis of public domain data supporting the link between this microRNA seed-family, their tumor suppressor targets and cancer cell proliferation. In conclusion we propose that AAGUGC-microRNAs are an integral part of an oncogenic signaling network, and that these findings have potential therapeutic implications, especially in selecting patients for EGFR-targeting therapy.
Project description:As a first step towards identifying the target genes of EGFR activity in glioma cells, genome-wide expression analyses were performed using the Affymetrix GeneChip Human Genome U133A array. To accomplish this, mRNA expression levels of these genes were measured in the glioblastoma cell lines, U87 and U178, engineered with EGFR by retrovirus transduction (termed U87-EGFR and U178-EGFR respectively), with or without 20 ng/mL EGF treatment for 3 h. U87 and U178 cells engineered to express EGFR were stimulated with or without EGF. The experiment was replicated twice for each U87 and U178 cells.
Project description:EGF and HRG, growth factor ligands for EGFR and ErbB3/4 receptor, induce transient and sustained ERK activity associated with cellular proliferation and differentiation of MCF-7 cells, respectively. To rigorously analyze the effect of ERK signal duration for mRNA expression dynamics and its relationship with cell determination, we modified the EGF-triggered ERK signal duration by changing the EGFR activation dynamics by impairing the ubiquitination and degradation process. Mutation of the six lysine residues (6KR; K692, K713, K730, K843, K905 and K946) of the EGFR responsible for ubiquitin conjugation has shown sustained phosphorylation of the receptor (Huang et al, 2006; Goh et al, 2010). Therefore we constructed the MCF-7 cell lines that stably express 6KR EGFR (6KR), and analyzed signaling and mRNA expression dynamics in response to EGF and HRG. Overall design: 6KR-EGFR (6KR) expressing MCF7 human breast cancer cells were stimulated by the growth hormone (epidermal growth factor (EGF) or heregulin (HRG)). Control was set as non-treated cells.
Project description:Analysis of miRNA expression in human breast cancer samples with Agilent's miRNA arrays. These samples are part of a study where we have investigated the mammalian cell proliferation control network consisting of transcription regulators, E2F and p53, their targets, and a family of 14 microRNAs. We observed that indicative of their significance, expression of these microRNAs is down-regulated in senescent cells and in breast cancers harboring wild-type p53. These microRNAs are repressed by p53 in an E2F1-mediated manner. Abstract of paper: Normal cell growth is governed by a complicated biological system, featuring multiple levels of control, often deregulated in cancers. The role of microRNAs in the control of gene expression is now increasingly appreciated, yet their involvement in controlling cell proliferation is still not well understood. Here we investigated the mammalian cell proliferation control network consisting of transcription regulators, E2F and p53, their targets, and a family of 14 microRNAs. Indicative of their significance, expression of these microRNAs is down-regulated in senescent cells and in breast cancers harboring wild-type p53. These microRNAs are repressed by p53 in an E2F1-mediated manner. Furthermore, we show that these microRNAs silence anti-proliferative genes, which themselves are E2F1 targets. Thus, microRNAs and transcriptional regulators appear to cooperate in the framework of a multi-gene transcriptional and post-transcriptional feed-forward loop. Finally, we show that, similarly to p53 inactivation, overexpression of representative microRNAs promotes proliferation and delays senescence, manifesting the detrimental phenotypic consequence of perturbations in this circuit. Together these findings position microRNAs as novel key players in the mammalian cellular proliferation network. Keywords: Breast Cancer, miRNA, p53. 18 Primary human breast cancer samples analyzed for their miRNA expression. From two to four replicates were performed for each sample. Quality check (QC) were performed with Feature Extraction 22.214.171.124 and arrays not passing QC were excluded
Project description:For the purpose of analyzing mechanisms related to the cis-diamminedichloroplatinum (CDDP) resistance in head and neck squamous cell carcinoma (head and neck SCC), we employed a nasal squamous cell carcinoma (nasal SCC) cell line RPMI2650 and its CDDP resistant substrain RPMI2650CR previously described. The identification of the resistance-related microRNA (miR) clusters was conducted between RPMI2650CR and RPMI2650 using microRNA microarray. microRNA expression of parental and CDDP resistant was measured with or without CDDP treatment in duplicate.
Project description:Gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), induces substantial clinical responses for non-small cell lung cancer (NSCLC) cells harboring EGFR activating mutations, but most of them invariably develop resistance. By generating a gefitinib resistance (PC9GR) from a human NSCLC-derived drug sensitive cell line (PC9), we studied differences of transcription dynamics between them by the aid of a computational decoupling of hidden regulatory signals from time course gene expression profiles. Given a collection of transcription factors (TFs) and their regulatory targets, the method captured temporally-synchronized shifts in evolving expression of target genes sharing each TF regulatory unit, and drew underlying regulatory signals. The analysis identified sterol regulatory element binding protein 1 (SREBP-1) as a key regulatory agent that facilitates the maintenance of drug tolerance, involving transcription controls of a G1-specific cyclin dependent kinase inhibitor whose expression was specifically elevated in PC9, but in turn, reduced in PC9GR Gefitinib-resistance cell line (PC9GR) was established derived from lung adenocarcinoma cell line PC9. PC9 cells and PC9GR cells were treated with the four different conditions, control (No treatment), EGF-treatment, gefitinib-treatment, and both gefitinib and EGF-treatment. In each condition, the gene expression was measured at 26 time points during 24 hrs.
Project description:Cylindromatosis tumor suppressor protein (CYLD) is deubiquitinase, best known as an essential negative regulator of the NFkB pathway. Previous studies have suggested an involvement of CYLD in epidermal growth factor (EGF)-dependent signal transduction as well, as it was found enriched within the tyrosine-phosphorylated complexes in cells stimulated with the growth factor. EGF receptor (EGFR) signaling participates in central cellular processes and its tight regulation, partly through ubiquitination cascades, is decisive for a balanced cellular homeostasis. Here, using a combination of mass spectrometry-based quantitative proteomic approaches with biochemical and immunofluorescence strategies, we demonstrate the involvement of CYLD in the regulation of the ubiquitination events triggered by EGF. Our data show that CYLD regulates the magnitude of ubiquitination of several major effectors of the EGFR pathway by assisting the recruitment of the ubiquitin ligase Cbl-b to the activated EGFR complex. Notably, the deficiency of CYLD impairs the interaction of EGFR with Cbl-b, which leads to a reduced ubiquitination of the receptor followed by its decreased degradation. This represents a previously uncharacterized strategy exerted by this deubiquitinase and tumors pressor for the negative regulation of a tumorigenic signaling pathway.