“…NHE1 is a plasma membrane-bound glycoprotein comprised of 815 amino acids (44). The precise crystal structure of the full-length NHE1 protein has not yet been resolved but topology models and cysteine accessibility experiments (45-47) reveal a hydrophobic transmembrane NH2-terminal domain of 12 transmembrane segments (amino acids 1-500) through which ion exchange occurs.…”
Section: Nhe1: the Major Cellular Regulator Of Ph Homeostasismentioning
confidence: 99%
“…This is followed by a hydrophilic COOH-terminal cytosolic domain (amino acids 501-815). The cytosolic domain regulates ion flux and its actions are modified by phosphorylation and the binding of intracellular proteins and lipids (44,48).…”
Section: Nhe1: the Major Cellular Regulator Of Ph Homeostasismentioning
Please cite this article as: Amith Schammim Ray, Fliegel Larry.Na+/H+ exchangermediated hydrogen ion extrusion as a carcinogenic signal in triple-negative breast cancer etiopathogenesis and prospects for its inhibition in therapeutics.Seminars in Cancer Biology http://dx.doi. org/10.1016/j.semcancer.2017.01.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Abstract (250 words):Breast cancer is the leading cause of cancer-related death in women in Europe and North America, and metastasis is the primary cause of fatality in patients with breast cancer. While some breast cancers are quite treatable, the triple-negative breast cancers are more metastatic and resistant to chemotherapy. There is clearly an urgent need for better treatments for this form of the disease. Breast cancer is characterized by genetically complex intra-tumour heterogeneity, particularly within the triple-negative clinical subtype. This complicates treatment options, so the development of specifically targeted chemotherapy for less treatable forms is critical.Dysregulation of pH homeostasis is a common factor in breast tumour cells. This occurs in concert with a metabolic switch to aerobic glycolysis that occurs at the onset of oncogenic transformation. The Na + /H + exchanger isoform 1 (NHE1) is the major pH regulatory protein involved in the increased proton extrusion of breast cancer cells. Its increased activity results in intracellular alkalinisation and extracellular acidification that drives cancer progression. The acidification of the extracellular tumour microenvironment also contributes to the development of chemotherapy resistance. In this review, we outline the role of H + as a carcinogenic signal and the role and regulation of NHE1 as a trigger for metastasis. We review recent evidence supporting the use of pharmacological inhibitors of NHE1 as a viable treatment option for triplenegative breast cancer.
“…NHE1 is a plasma membrane-bound glycoprotein comprised of 815 amino acids (44). The precise crystal structure of the full-length NHE1 protein has not yet been resolved but topology models and cysteine accessibility experiments (45-47) reveal a hydrophobic transmembrane NH2-terminal domain of 12 transmembrane segments (amino acids 1-500) through which ion exchange occurs.…”
Section: Nhe1: the Major Cellular Regulator Of Ph Homeostasismentioning
confidence: 99%
“…This is followed by a hydrophilic COOH-terminal cytosolic domain (amino acids 501-815). The cytosolic domain regulates ion flux and its actions are modified by phosphorylation and the binding of intracellular proteins and lipids (44,48).…”
Section: Nhe1: the Major Cellular Regulator Of Ph Homeostasismentioning
Please cite this article as: Amith Schammim Ray, Fliegel Larry.Na+/H+ exchangermediated hydrogen ion extrusion as a carcinogenic signal in triple-negative breast cancer etiopathogenesis and prospects for its inhibition in therapeutics.Seminars in Cancer Biology http://dx.doi. org/10.1016/j.semcancer.2017.01.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Abstract (250 words):Breast cancer is the leading cause of cancer-related death in women in Europe and North America, and metastasis is the primary cause of fatality in patients with breast cancer. While some breast cancers are quite treatable, the triple-negative breast cancers are more metastatic and resistant to chemotherapy. There is clearly an urgent need for better treatments for this form of the disease. Breast cancer is characterized by genetically complex intra-tumour heterogeneity, particularly within the triple-negative clinical subtype. This complicates treatment options, so the development of specifically targeted chemotherapy for less treatable forms is critical.Dysregulation of pH homeostasis is a common factor in breast tumour cells. This occurs in concert with a metabolic switch to aerobic glycolysis that occurs at the onset of oncogenic transformation. The Na + /H + exchanger isoform 1 (NHE1) is the major pH regulatory protein involved in the increased proton extrusion of breast cancer cells. Its increased activity results in intracellular alkalinisation and extracellular acidification that drives cancer progression. The acidification of the extracellular tumour microenvironment also contributes to the development of chemotherapy resistance. In this review, we outline the role of H + as a carcinogenic signal and the role and regulation of NHE1 as a trigger for metastasis. We review recent evidence supporting the use of pharmacological inhibitors of NHE1 as a viable treatment option for triplenegative breast cancer.
“…The precise structure of NHE1 (or of any other mammalian NHE) is not known, but the structures of two bacterial homologues, NhaA of E. coli and NapA of T. thermophilus have been determined [71,89]. A recent review describes the current structural model of NHE1 [88].…”
Section: Slc9a1-nhe1mentioning
confidence: 99%
“…This article expands on a recent review [46] in particular our knowledge about the intracellular NHEs. Due to size limitations, we decided not to include information on NHE structure but excellent reviews of this topic have recently been published [88,81] . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 …”
The SLC9 gene family encodes Na + /H + exchangers (NHEs). These transmembrane proteins transport ions across lipid bilayers in a diverse array of species from prokaryotes to eukaryotes, including plants, fungi and animals. They utilize the electrochemical gradient of one ion to transport another ion against its electrochemical gradient. Currently, 13 evolutionarily conserved NHE isoforms are known in mammals [46,22,128]. The SLC9 gene family (solute carrier classification of transporters:www.bioparadigms.org) is divided into three subgroups [46]. The SLC9A subgroup encompasses plasmalemmal isoforms NHE1-5 (SLC9A1-5) and the predominantly intracellular isoforms NHE6-9 (SLC9A6-9). The SLC9B subgroup consists of two recently cloned isoforms, NHA1 and NHA2 (SLC9B1 and SLC9B2, respectively). The SLC9C subgroup consist of a sperm specific plasmalemmal NHE (SLC9C1) and a putative NHE, SLC9C2, for which there is currently no functional data [46].NHEs participate in the regulation of cytosolic and organellar pH as well as cell volume. In the intestine and kidney, NHEs are critical for transepithelial movement of Na + and HCO 3 -and thus for whole body volume and acid-base homeostasis [46]. Mutations in the NHE6 or NHE9 genes cause neurological disease in humans and are currently the only NHEs directly linked to human disease.However, it is becoming increasingly apparent that members of this gene family contribute to the pathophysiology of multiple human diseases.
“…In the nephron, individual NHE isoforms have different functions. These functions are reflected in their differential expression along the segments of the nephron, their localization in renal epithelial cells at the basolateral (e.g., isoform NHE1) or apical surface (e.g., isoform NHE3), and their activation in response to distinct agonists [4][5][6][7][8][9][10][11][12][13].…”
This article reviews the main body of knowledge regarding NHE1 and NHE3 exchangers and their interaction with Angiotensin II, Angiotensin-(1-7), Aldosterone and Arginine Vasopressin, particularly their renal actions. This work addresses the biphasic effects of different hormonal doses on NHE1 or NHE3 in proximal tubule in Wistar, SHR (hypertensives) and their control WKY (normotensives) rats or MDCK cells (which share similarities with the collecting duct). The hormones were applied alone, with their inhibitors or plus agents that change the [Ca 2+ ]i. The data are compatible with hormonal stimulation of these exchangers by increases of [Ca 2+ ]i in lower range, and inhibition at high [Ca 2+ ]i. In MDCK cells and Wistar rats, low doses of ANG II, ALDO or AVP stimulated the exchangers, while high doses inhibited them. ANG-(1-7), in Wistar or WKY rats has inverse, dose-dependent effects. In SHR rats, the biphasic effects of ANG-(1-7) were similar to the effects of ANG II, ALDO or AVP in Wistar rats. The interactions between these effects may represent a mechanism that regulates extracellular volume. In hypertensives animals, a high plasma level of ANG-(1-7) inhibited NHE3 in the proximal tubule, which mitigated hypertension. Figure 6 shows a schematic model to describe these biphasic hormonal effects.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.