Project description:The presence of nuclear ERBB2 receptor-type tyrosine kinase is one of the causes of the resistance to membrane ERBB2-targeted therapy in breast cancers. It has been previously reported that this nuclear location arises through at least two different mechanisms: proteolytic shedding of the extracellular domain of the full-length receptor and translation of the messenger RNA (mRNA)-encoding ERBB2 from internal initiation codons. Here, we report a new mechanism and function where a significant portion of nuclear ERBB2 results from the translation of the variant ERBB2 mRNA under the transcriptional control of a distal promoter that is actively used in breast cancer cells. We show that both membrane ERBB2a and nuclear ERBB2b isoforms are prevalently expressed in breast cancer cell lines and carcinoma samples. The ERBB2b isoform, which is translated from mRNA variant 2, can directly translocate into the nucleus due to the lack of the signal peptide which is required for an intermediate membrane location. Small interfering RNA-mediated gene silencing showed that ERBB2b can repress ERBB2a expression, encoded by variant 1, whereas ERBB2a activates ERBB2b. Nuclear ERBB2 binding to its own promoter was revealed by chromatin immunoprecipitation assay. Altogether, our results provide new insights into the origin and function of nuclear ERBB2 where it can participate at the same time in a positive or a negative feedback autoregulatory loop, dependent on which of its promoters this bona fide transcription factor is acting. They also provide a new understanding for the resistance to therapies targeting the membrane-anchored ERBB2 in breast cancer.
Project description:V-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (ERBB2; synonyms HER2, NEU) encodes a transmembrane glycoprotein with tyrosine kinase-specific activity that acts as a major switch in different signal-transduction processes. ERBB2 amplification and overexpression have been found in a number of human cancers, including breast, ovary and kidney carcinoma. Our aim was to detect ERBB2-regulated target genes regulated in Erbb2 transfected murine fibroblast cells after tetracycline treatment to stop the overexpression of ERBB2. Changes in gene expression patterns in these cells after the switch-off of Erbb2 expression was analysed after 8 different periods of time after the treatement (1h-7d). Identification of co-regulated genes and in cluster analysis were performed. Keywords: Erbb2, cDNA microarrays, murine fibroblasts,
Project description:V-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (ERBB2; synonyms HER2, NEU) encodes a transmembrane glycoprotein with tyrosine kinase-specific activity that acts as a major switch in different signal-transduction processes. ERBB2 amplification and overexpression have been found in a number of human cancers, including breast, ovary and kidney carcinoma. Our aim was to detect ERBB2-regulated target genes regulated in Erbb2 transfected murine fibroblast cells after tetracycline treatment to stop the overexpression of ERBB2. Changes in gene expression patterns in these cells after the switch-off of Erbb2 expression was analysed after 8 different periods of time after the treatement (1h-7d). Identification of co-regulated genes and in cluster analysis were performed. Keywords: Erbb2, cDNA microarrays, murine fibroblasts, gene expression levels of 8 different measurements after tetracycline treatment (1h, 2h, 4h, 12h, 24h, 3d, 5d and 7d) were compared to the non-treated NIH3T3 cell line. As control two different untreated NIH3T3 cell line were ananysed. For all comparisons 4 experiments have been performed including 2 dye swaps.
Project description:Cancers overexpressing the ERBB2 oncogene are aggressive and associated with a poor prognosis. Trastuzumab is a ERBB2 specific recombinant antibody employed for the treatment of these diseases since it blocks ERBB2 signaling causing growth arrest and survival inhibition. While the effects of Trastuzumab on ERBB2 cancer cells are well known, those on the extracellular vesicles released from these cells are scarce. This study focused on ERBB2+ breast cancer cells and aimed to establish what type of EVs they release and whether Trastuzumab affects their morphology and molecular composition. To these aims, we performed immunoelectron microscopy, immunoblot, and high-resolution mass spectrometry analyses on EVs purified by differential centrifugation of culture supernatant. Here we show that EVs released from ERBB2+ breast cancer cells are polymorphic in size and appearance, and that ERBB2 is preferentially associated with large (120 nm) EVs. Moreover, we report that Tz induces the expression of a specific glycosylated 50 kDa isoform of the CD63 tetraspanin and modulates the expression of 51 EVs proteins, including TOP1. As these proteins are functionally associated with organelle organization, cytokinesis, and response to lipids, we suggest that Tz may influence these cellular processes in target cells at distant sites via modified EVs.
Project description:Non-syndromic congenital heart defects (CHD) are occasionally familial and left ventricular out flow tract obstruction (LVOTO) defects are among the subtypes with the highest hereditability. The aim of this study was to evaluate the pathogenicity of a heterozygous ERBB2 variant R599C identified in three families with LVOTO defects.
Project description:V-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (ERBB2; synonyms HER2, NEU) encodes a transmembrane glycoprotein with tyrosine kinase-specific activity that acts as a major switch in different signal-transduction processes. ERBB2 amplification and overexpression have been found in a number of human cancers, including breast, ovary and kidney carcinoma. Our aim was to detect ERBB2- regulated target genes that contribute to its tumorigenic effect on a genomewide scale. The differential gene expression profile of ERBB2- transfected and wild-type mouse fibroblasts was monitored employing DNA microarrays. Regulated expression of selected genes was verified by RT-PCR and validated by Western blot analysis. Genomewide gene expression profiling identified (i) known targets of ERBB2 signaling, (ii) genes implicated in tumorigenesis but so far not associated with ERBB2 signaling as well as (iii) genes not yet associated with oncogenic transformation, including novel genes without functional annotation. We also found that at least a fraction of coexpressed genes are closely linked on the genome. ERBB2 overexpression suppresses the transcription of antiangiogenic factors (e.g., Sparc, Timp3, Serpinf1) but induces expression of angiogenic factors (e.g., Klf5, Tnfaip2, Sema3c). Profiling of ERBB2-dependent gene regulation revealed a compendium of potential diagnostic markers and putative therapeutic targets. Identification of coexpressed genes that colocalize in the genome may indicate gene regulatory mechanisms that require further study to evaluate functional coregulation. Erbb2 transfected NIH3T3 cells versus un-transfected cells, 4 technical replicates including two colour swap experiments
Project description:V-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (ERBB2; synonyms HER2, NEU) encodes a transmembrane glycoprotein with tyrosine kinase-specific activity that acts as a major switch in different signal-transduction processes. ERBB2 amplification and overexpression have been found in a number of human cancers, including breast, ovary and kidney carcinoma. Our aim was to detect ERBB2- regulated target genes that contribute to its tumorigenic effect on a genomewide scale. The differential gene expression profile of ERBB2- transfected and wild-type mouse fibroblasts was monitored employing DNA microarrays. Regulated expression of selected genes was verified by RT-PCR and validated by Western blot analysis. Genomewide gene expression profiling identified (i) known targets of ERBB2 signaling, (ii) genes implicated in tumorigenesis but so far not associated with ERBB2 signaling as well as (iii) genes not yet associated with oncogenic transformation, including novel genes without functional annotation. We also found that at least a fraction of coexpressed genes are closely linked on the genome. ERBB2 overexpression suppresses the transcription of antiangiogenic factors (e.g., Sparc, Timp3, Serpinf1) but induces expression of angiogenic factors (e.g., Klf5, Tnfaip2, Sema3c). Profiling of ERBB2-dependent gene regulation revealed a compendium of potential diagnostic markers and putative therapeutic targets. Identification of coexpressed genes that colocalize in the genome may indicate gene regulatory mechanisms that require further study to evaluate functional coregulation.
Project description:Non-syndromic congenital heart defects (CHD) are occasionally familial and left ventricular out flow tract obstruction (LVOTO) defects are among the subtypes with the highest hereditability. The aim of this study was to evaluate the pathogenicity of a heterozygous ERBB2 variant R599C identified in three families with LVOTO defects.
Project description:The mechanisms of ErbB2 signalling and the effects of its overexpression are not fully understood. Herein, SILAC expression profiling and phosphopeptide enrichment of a relevant, non-transformed, immortalized human mammary luminal epithelial cell model were used to profile ErbB2-dependent differences in protein expression and phosphorylation events triggered via EGFR (EGF treatment) and ErbB3 (HRGbeta1 treatment) in the context of ErbB2 overexpression. Bioinformatics analysis was used to infer changes in cellular processes and signalling events. We demonstrate the complexity of the responses to oncogene expression and growth factor signalling and identify protein changes relevant to ErbB2-dependent altered cellular phenotype, in particular cell cycle progression and hyper-proliferation, reduced adhesion and enhanced motility. Numerous novel sites of growth factor-regulated phosphorylation were also identified that were enhanced by ErbB2 overexpression and we putatively link these to altered cell behaviour. Moreover, we have defined a novel mechanism by which ErbB signalling suppresses basal interferon signalling that would promote the survival and proliferation of mammary luminal epithelial cells.
Project description:Exposure to ultraviolet (UV) irradiation is the major cause of nonmelanoma skin cancer, the most common form of cancer in the United States. UV irradiation has a variety of effects on the skin associated with carcinogenesis, including DNA damage and effects on signal transduction. The alterations in signaling caused by UV regulate inflammation, cell proliferation, and apoptosis. UV also activates the orphan receptor tyrosine kinase and proto-oncogene Erbb2 (HER2/neu). In this study, we demonstrate that the UV-induced activation of Erbb2 regulates the response of the skin to UV. Inhibition or knockdown of Erbb2 before UV irradiation suppressed cell proliferation, cell survival, and inflammation after UV. In addition, Erbb2 was necessary for the UV-induced expression of numerous proinflammatory genes that are regulated by the transcription factors nuclear factor-kappaB and Comp1, including interleukin-1beta, prostaglandin-endoperoxidase synthase 2 (Cyclooxygenase-2), and multiple chemokines. These results reveal the influence of Erbb2 on the UV response and suggest a role for Erbb2 in UV-induced pathologies such as skin cancer. Keywords: time course, ultraviolet irradiation, UV, erbB2, mouse skin