Overexpression of ERBB4 JM-a CYT-1 and CYT-2 isoforms in transgenic mice reveals isoform-specific roles in mammary gland development and carcinogenesis.

Introduction: Human Epidermal Growth Factor Receptor (ERBB4/HER4) belongs to the Epidermal Growth Factor receptor/ERBB family of receptor tyrosine kinases. While ERBB1, ERBB2 and ERBB3 are often overexpressed or activated in breast cancer, and are oncogenic, the role of ERBB4 in breast cancer is uncertain. Some studies suggest a tumor suppressor role of ERBB4, while other reports suggest an oncogenic potential.

Convergent and divergent cellular responses by ErbB4 isoforms in mammary epithelial cells.

Unlabelled: Associations of ErbB4 (ERBB4/HER4), the fourth member of the EGFR family, with cancer are variable, possibly as a result of structural diversity of this receptor. There are multiple structural isoforms of ERBB4 arising by alternative mRNA splicing, and a subset undergo proteolysis that releases membrane-anchored and soluble isoforms that associate with transcription factors and coregulators to modulate transcription. To compare the differential and common signaling activities of full-length (FL) and soluble intracellular isoforms of ERBB4, four JM-a isoforms (FL and soluble intracellular domain (ICD) CYT-1 and CYT-2) were expressed in isogenic MCF10A cells and their biologic activities were analyzed.

Interactions of ErbB4 and Kap1 connect the growth factor and DNA damage response pathways.

ErbB4 is unusual among receptor tyrosine kinases because some isoforms can be efficiently cleaved at the plasma membrane to release a soluble intracellular domain. The cleavage product has high kinase activity and homes to the nucleus. A screen for proteins that associate with the ErbB4 intracellular domain identified candidate interactors including ITCH, WWP2, Nucleolin, and Krab-associated protein 1 (Kap1).

Regulation of non-AU-rich element containing c-fms proto-oncogene expression by HuR in breast cancer.

The role of RNA-binding proteins in cancer biology is recognized increasingly. The nucleocytoplasmic shuttling and AU-rich RNA-binding protein HuR stabilizes several cancer-related target mRNAs. The proto-oncogene c-fms, whose 3'untranslated region (3'UTR) is not AU-rich, is associated with poor prognosis in breast cancer.

The multifunctional protein glyceraldehyde-3-phosphate dehydrogenase is both regulated and controls colony-stimulating factor-1 messenger RNA stability in ovarian cancer.

Although glyceraldehyde-3-phosphate dehydrogenase's (GAPDH) predilection for AU-rich elements has long been known, the expected connection between GAPDH and control of mRNA stability has never been made. Recently, we described GAPDH binding the AU-rich terminal 144 nt of the colony-stimulating factor-1 (CSF-1) 3' untranslated region (UTR), which we showed to be an mRNA decay element in ovarian cancer cells. CSF-1 is strongly correlated with the poor prognosis of patients with ovarian cancer.

Glyceraldehyde-3-phosphate dehydrogenase binds to the AU-Rich 3' untranslated region of colony-stimulating factor-1 (CSF-1) messenger RNA in human ovarian cancer cells: possible role in CSF-1 posttranscriptional regulation and tumor phenotype.

The overexpression of the colony-stimulating factor-1(CSF-1) by epithelial ovarian cancer cells enhances invasiveness and metastatic properties, contributing to the poor prognosis of the patients. It has been suggested that CSF-1 3' untranslated region containing AU-rich elements (ARE) could regulate CSF-1 posttranscriptional expression and be responsible for its aberrant abundance in such cancer cells. In this study, normal (NOSE.

SGK1, a potential regulator of c-fms related breast cancer aggressiveness.

The aggressive behavior of breast cancer cells can at times be modulated by hormonal mechanisms. Exposure to glucocorticoids (GC) has been shown to stimulate the invasiveness, motility and adhesiveness of breast cancer cells containing the glucocorticoid receptor. This is largely explained by GC-associated overexpression of the c-fms proto-oncogene, which encodes the receptor for the colony stimulating factor-1 (CSF-1).

cDNA microarray analysis of invasive and tumorigenic phenotypes in a breast cancer model.

The fms oncogene encodes the macrophage colony-stimulating factor receptor (CSF1R), a transmembrane tyrosine kinase receptor, which is abnormally expressed in breast cancer. Transfection of wild-type CSF1R into HC11 mammary epithelial cells (HC11-CSF1R) renders the transfectants capable of in vitro local invasion and in vivo tumorigenesis. Transfection with CSF1R mutated to express phe at the tyr-721 autophosphorylation site (HC11-CSF1R-721) creates a phenotype that lacks metastastic competence but maintains local invasiveness.

Independent regulation of invasion and anchorage-independent growth by different autophosphorylation sites of the macrophage colony-stimulating factor 1 receptor.

Invasion of tissue by macrophages and implantation into the uterine wall by placental trophoblasts are known to be regulated by the macrophage colony-stimulating factor (CSF-1) and its receptor (CSF-1R, the product of the c-fms proto-oncogene). Recently, the clinical importance of CSF-1 and CSF-1R in invasive breast carcinoma has been recognized, but the significance of coexpression of CSF-1 and CSF-1R in mammary epithelial cell invasion has not been explored. In the present study, we investigated the invasive potential of a noninvasive, CSF-1R-negative, mouse mammary epithelial cell line (HC11) expressing a high level of CSF-1, which was stably transfected with the mouse wild-type CSF-1R.

Na, K-ATPase isoform gene expression in normal and hypertrophied dog heart.

Objectives: The catalytic alpha subunit of the sodium-potassium ATPase, the target of digitalis glycosides, has three isoforms; the expression of these isoforms is tissue-specific and developmentally regulated. While the effect of pressure overload on Na, K-ATPase isoform expression has been studied in rodent heart, there are no systematic data on this question in hearts of larger animals, which differ from those of rodents both in isoform composition and in glycoside sensitivity. Thus, we investigated the expression of Na, K-ATPase isoforms in normal dog heart; we also examined the effect of experimental left ventricular hypertrophy on isoform expression.

Developmental regulation of Na, K-ATPase in rat lung.

Late in gestation lung epithelium changes from net chloride and fluid secretion to sodium and fluid absorption. Fluid resorption is required for postnatal gas exchange and occurs by combined action of epithelial sodium channels and Na, K-ATPase. We hypothesized that alveolar epithelial Na, K-ATPase increases perinatally.

Transcriptional regulation of the c-fms (CSF-1R) proto-oncogene in human breast carcinoma cells by glucocorticoids.

Expression of the macrophage colony stimulating factor CSF-1 and its receptor, the c-fms proto-oncogene, has been observed in macrophages, trophoblast and in a variety of neoplasms of epithelial origin including those of the breast. We have reported earlier (Oncogene, 1991, 6: 941-952) that c-fms transcript and protein expression were dramatically increased in several breast carcinoma cell lines by glucocorticoids which are essential humoral regulators of normal mammary epithelial cell differentiation. In this communication, we demonstrate that levels of c-fms transcript and protein increased significantly within the first few hours of glucocorticoid treatment, and that these increases were completely abolished by pretreatment of cells with mifepristone (RU486).

Post-transcriptional regulation of c-fms proto-oncogene expression by dexamethasone and of CSF-1 in human breast carcinomas in vitro.

The c-fms proto-oncogene encodes the receptor for a hematopoietic growth factor, CSF-1. Recently, the importance of c-fms and its ligand CSF-1 in malignancies of non-hematopoietic origin, such as breast, ovarian, endometrial, pulmonary, and trophoblastic cancers has been recognized. We have previously shown that glucocorticoids induce a large increase in c-fms mRNA and protein levels in breast carcinoma cell lines.

Posttranscriptional regulation of colony-stimulating factor-1 (CSF-1) and CSF-1 receptor gene expression during inhibition of phorbol-ester-induced monocytic differentiation by dexamethasone and cyclosporin A: potential involvement of a destabilizing protein.

Colony stimulating factor-1 (CSF-1) and its receptor (encoded by the c-fms proto-oncogene) have long been recognized as playing an important role in monocytic differentiation. However, the regulation of expression of the CSF-1 and c-fms genes during inhibition of monocytic differentiation has not been fully characterized. The present studies demonstrate that dexamethasone (dex) and cyclosporin A (CsA) resulted in inhibition of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced monocytic differentiation of HL60 cells, as well as TPA induction of c-fms and CSF-1 transcripts.

Expression of alpha isoforms of the Na,K-ATPase in human heart.

We studied expression of isoforms of Na,K-ATPase in normal and diseased human hearts. Na,K-ATPase alpha-isoform mRNA in samples from normal human left ventricle (LV) was composed of 62.5%, alpha 1, 15% alpha 2 and 22.

Differential translation of the Na,K-ATPase subunit mRNAs.

Expression of the Na,K-ATPase alpha and beta subunit genes is influenced by a complex series of regulatory pathways. For example, unequal amounts of subunit mRNAs are detected in several tissues, both at rest and upon mRNA induction, even though equal quantities of subunit proteins exist. We therefore studied mRNA stability and translational efficiency of wild type, deletion mutant, and chimeric subunit mRNAs in a cell-free translation system, to examine the possible role of post-transcriptional events in regulating subunit expression.

Changes in Na,K-ATPase gene expression during granulocytic differentiation of HL60 cells.

During granulocytic differentiation of HL60 cells, immediate reduction of ouabain-sensitive potassium flux is observed within the first 12 hours of addition of dimethyl sulfoxide (DMSO). We show that gene expression of the alpha 3 isoform of Na+,K(+)-ATPase, which encodes an ouabain-inhibitable Na+,K(+)-ATPase activity, significantly declines during the first 24 hours of granulocytic differentiation by DMSO of HL60 cells. The more common alpha 1 isoform decreases, but more gradually over 72 hours of DMSO induction.

The A2 isoform of rat Na+,K(+)-adenosine triphosphatase is active and exhibits high ouabain affinity when expressed in transfected fibroblasts.

The alpha isoforms of the Na+,K(+)-ATPase (Na+ pump) are expressed with developmental and tissue heterogeneity in rodents and possess different sensitivity to inhibition by ouabain. We directly characterized the ouabain sensitivity of the rat A2 (alpha 2) isoform by transfecting NIH 3T3 cells with rat A2. The treated cells exhibit high affinity (40 nM) ouabain binding with a density of 2 pmol/mg protein.

Distinct molecular signals for nuclear import of the nucleolar snRNA, U3.

Export to the cytoplasm of U3 RNA transcribed from a rat U3 gene injected into the nucleus of Xenopus oocytes indicates that the biogenesis of U3 RNA, like that of the previously studied Sm-precipitable nucleoplasmic snRNAs (U1, U2, U4, and U5), includes a cytoplasmic phase. The regulation of import of the U3 snRNA into the nucleus has been analyzed by injection of synthetic human U3 transcripts into the cytoplasm of Xenopus oocytes. Binding of the major autoantigenic protein of the U3 snRNP, fibrillarin, and cap trimethylation can occur in the cytoplasm, but neither are required for import.

The cardiac conduction system in the rat expresses the alpha 2 and alpha 3 isoforms of the Na+,K(+)-ATPase.

The sodium pump is crucial for the function of the heart and of the cardiac conduction system, which initiates the heartbeat. The alpha (catalytic) subunit of this pump has three isoforms; the alpha 1 isoform is ubiquitous, but the alpha 2 and alpha 3 isoforms are localized to excitable tissue. Because rodent alpha 2 and alpha 3 isoforms are relatively sensitive to ouabain, which also slows cardiac conduction, we studied heart-cell-specific expression of pump isoform genes.

Upregulation of rat lung Na-K-ATPase during hyperoxic injury.

A major function of the alveolar epithelium is to keep the airspace free of fluid and preserve gas exchange. Since Na-K-ATPase is believed to be important in this process, we hypothesized that Na-K-ATPase in the rat lung would increase in response to acute lung injury with pulmonary edema. Na-K-ATPase localization, mRNA expression, and protein levels were determined in hyperoxic lung injury.

Detection of the Na(+)-K(+)-ATPase alpha 3-isoform in multinucleated macrophages.

We previously reported that multinucleated macrophages express a high concentration of Na(+)-K(+)-ATPases that are concentrated on the nonadherent domain of their plasma membrane (A. Vignery, T. Niven-Fairchild, D.

Cytoarchitectural relationships between [3H]ouabain binding and mRNA for isoforms of the sodium pump catalytic subunit in rat brain.

We examined the cell type-specific expression of the alpha 1, alpha 2, and alpha 3 subunits of the sodium pump in rat brain using in situ hybridization and [3H]ouabain autoradiography. These techniques allowed us to colocalize mRNA and functional alpha 2/alpha 3 pumps on adjacent sections. The perikarya of many neurons possessed high levels of alpha 1 and/or alpha 3 transcripts, while alpha 2 mRNA appeared to be present in only a few neuronal types.

Expression of multiple Na+,K+-adenosine triphosphatase isoform genes in human hematopoietic cells. Behavior of the novel A3 isoform during induced maturation of HL60 cells.

Multiple isoenzymes of the Na+,K+-ATPase (alpha, alpha+, and alpha 3) have been identified by molecular cloning (Shull, G. E., J.