1
|
Greenwald E, Posner C, Bharath A, Lyons A, Salmerón C, Sriram K, Wiley SZ, Insel PA, Zhang J. GPCR Signaling Measurement and Drug Profiling with an Automated Live-Cell Microscopy System. ACS Sens 2023; 8:19-27. [PMID: 36602887 PMCID: PMC9994309 DOI: 10.1021/acssensors.2c01341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A major limitation of time-lapse microscopy combined with fluorescent biosensors, a powerful tool for quantifying spatiotemporal dynamics of signaling in single living cells, is low-experimental throughput. To overcome this limitation, we created a highly customizable, MATLAB-based platform: flexible automated liquid-handling combined microscope (FALCOscope) that coordinates an OpenTrons liquid handler and a fluorescence microscope to automate drug treatments, fluorescence imaging, and single-cell analysis. To test the feasibility of the FALCOscope, we quantified G protein-coupled receptor (GPCR)-stimulated Protein Kinase A activity and cAMP responses to GPCR agonists and antagonists. We also characterized cAMP dynamics induced by GPR68/OGR1, a proton-sensing GPCR, in response to variable extracellular pH values. GPR68-induced cAMP responses were more transient in acidic than neutral pH values, suggesting a pH-dependence for signal attenuation. Ogerin, a GPR68 positive allosteric modulator, enhanced cAMP response most strongly at pH 7.0 and sustained cAMP response for acidic pH values, thereby demonstrating the capability of the FALCOscope to capture allosteric modulation. At a high concentration, ogerin increased cAMP signaling independent of GPR68, likely via phosphodiesterase inhibition. The FALCOscope system thus enables enhanced throughput single-cell dynamic measurements and is a versatile system for interrogating spatiotemporal regulation of signaling molecules in living cells and for drug profiling and screening.
Collapse
Affiliation(s)
- Eric Greenwald
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States
| | - Clara Posner
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
| | - Ananya Bharath
- Department of Chemical Engineering, University of California, San Diego, La Jolla, California 92093, United States
| | - Anne Lyons
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
| | - Cristina Salmerón
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States
| | - Krishna Sriram
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States
| | - Shu Z Wiley
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States
| | - Paul A Insel
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States.,Department of Medicine, University of California, San Diego, La Jolla, California 92093 United States
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States.,Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States.,Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| |
Collapse
|
2
|
Jian L, Shi-wei L, Dan J, Juan W, Wei Z. GPR84 potently inhibits osteoclastogenesis and alleviates osteolysis in bone metastasis of colorectal cancer. J Orthop Surg Res 2023; 18:3. [PMID: 36593458 PMCID: PMC9806886 DOI: 10.1186/s13018-022-03473-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 12/22/2022] [Indexed: 01/03/2023] Open
Abstract
The expression of GPR84 in bone marrow-derived monocytes/macrophages (BMMs) can inhibit osteoclast formation; however, its role in bone metastasis of colorectal cancer (CRC) is still unknown. To investigate the effects of GPR84 on bone metastasis of CRC, the murine CRC cell line MC-38 was injected into tibial bone marrow. We found that the expression of GPR84 in BMMs was gradually downregulated during bone metastasis of CRC, and the activation of GPR84 significantly prevented osteoclastogenesis in the tumor microenvironment. Mechanistically, the MAPK pathway mediated the effects of GPR84 on osteoclast formation. Moreover, we found that IL-11 at least partly inhibited the expression of GPR84 in the tumor microenvironment through the inactivation of STAT1. Additionally, activation of GPR84 could prevent osteolysis during bone metastasis of CRC. Our results suggest that CRC cells downregulate the expression of GPR84 in BMMs to promote osteoclastogenesis in an IL-11-dependent manner. Thus, GPR84 could be a potential therapeutic target to attenuate bone destruction induced by CRC metastasis.
Collapse
Affiliation(s)
- Li Jian
- Department of Orthopedics, General Hospital of Western Theater Command, Rongdu Avenue No. 270, Chengdu, 610000 People’s Republic of China ,grid.413856.d0000 0004 1799 3643Chengdu Medical College, Rongdu Avenue No. 601, Chengdu, 610000 People’s Republic of China
| | - Long Shi-wei
- Department of Orthopedics, General Hospital of Western Theater Command, Rongdu Avenue No. 270, Chengdu, 610000 People’s Republic of China
| | - Jing Dan
- Department of Orthopedics, General Hospital of Western Theater Command, Rongdu Avenue No. 270, Chengdu, 610000 People’s Republic of China
| | - Wu Juan
- Department of Pharmacy, General Hospital of Western Theater Command, Rongdu Avenue No. 270, Chengdu, 610000 People’s Republic of China
| | - Zheng Wei
- Department of Orthopedics, General Hospital of Western Theater Command, Rongdu Avenue No. 270, Chengdu, 610000 People’s Republic of China ,grid.413856.d0000 0004 1799 3643Chengdu Medical College, Rongdu Avenue No. 601, Chengdu, 610000 People’s Republic of China
| |
Collapse
|
3
|
Imenez Silva PH, Câmara NO, Wagner CA. Role of proton-activated G protein-coupled receptors in pathophysiology. Am J Physiol Cell Physiol 2022; 323:C400-C414. [PMID: 35759438 DOI: 10.1152/ajpcell.00114.2022] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Local acidification is a common feature of many disease processes such as inflammation, infarction, or solid tumor growth. Acidic pH is not merely a sequelae of disease but contributes to recruitment and regulation of immune cells, modifies metabolism of parenchymal, immune and tumor cells, modulates fibrosis, vascular permeability, oxygen availability and consumption, invasiveness of tumor cells, and impacts on cell survival. Thus, multiple pH-sensing mechanisms must exist in cells involved in these processes. These pH-sensors play important roles in normal physiology and pathophysiology, and hence might be attractive targets for pharmacological interventions. Among the pH-sensing mechanisms, OGR1 (GPR68), GPR4 (GPR4), and TDAG8 (GPR65) have emerged as important molecules. These G protein-coupled receptors are widely expressed, are upregulated in inflammation and tumors, sense changes in extracellular pH in the range between pH 8 and 6, and are involved in modulating key processes in inflammation, tumor biology, and fibrosis. This review discusses key features of these receptors and highlights important disease states and pathways affected by their activity.
Collapse
Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Niels Olsen Câmara
- Department of Immunology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| |
Collapse
|
4
|
de Vallière C, Bäbler K, Busenhart P, Schwarzfischer M, Maeyashiki C, Schuler C, Atrott K, Lang S, Spalinger MR, Scharl M, Ruiz-Castro PA, Hausmann M, Rogler G. A Novel OGR1 (GPR68) Inhibitor Attenuates Inflammation in Murine Models of Colitis. Inflamm Intest Dis 2021; 6:140-153. [PMID: 34722644 DOI: 10.1159/000517474] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/13/2021] [Indexed: 01/17/2023] Open
Abstract
Background and Aims Local extracellular acidification is associated with several conditions, such as ischemia, cancer, metabolic disease, respiratory diseases, and inflammatory bowel disease (IBD). Several recent studies reported a link between IBD and a family of pH-sensing G protein-coupled receptors. Our previous studies point to an essential role for OGR1 (GPR68) in the modulation of intestinal inflammation and fibrosis. In the current study, we evaluated the effects of a novel OGR1 inhibitor in murine models of colitis. Methods The effects of a novel small-molecule OGR1 inhibitor were assessed in the acute and chronic dextran sulfate sodium (DSS) murine models of colitis. Macroscopic disease indicators of intestinal inflammation were evaluated, and epithelial damage and immune cell infiltration and proliferation were assessed by immunohistochemistry. Results The OGR1 inhibitor ameliorated clinical parameters in acute and chronic DSS-induced colitis. In mice treated with the OGR1 inhibitor, endoscopy showed no thickening and normal vascularity, while fibrin was not detected. Histopathological findings revealed a decrease in severity of colonic inflammation in the OGR1 inhibitor group when compared to vehicle-DSS controls. In OGR1 inhibitor-treated mice, staining for the macrophage marker F4/80 and cellular proliferation marker Ki-67 revealed a reduction of infiltrating macrophages and slightly enhanced cell proliferation, respectively. This was accompanied by a reduction in pro-inflammatory cytokines, TNF and IL-6, and the fibrosis marker TGF-β1. Conclusion This is the first report providing evidence that a pharmacological inhibition of OGR1 has a therapeutic effect in murine colitis models. Our data suggest that targeting proton-sensing OGR1 using specific small-molecule inhibitors may be a novel therapeutic approach for the treatment of IBD.
Collapse
Affiliation(s)
- Cheryl de Vallière
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Katharina Bäbler
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Philipp Busenhart
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Marlene Schwarzfischer
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Chiaki Maeyashiki
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Cordelia Schuler
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Kirstin Atrott
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Silvia Lang
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Marianne R Spalinger
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Michael Scharl
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, Zurich, Switzerland
| | - Pedro A Ruiz-Castro
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Martin Hausmann
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland
| | - Gerhard Rogler
- Department of Gastroenterology and Hepatology, University Hospital Zurich, (USZ), University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, Zurich, Switzerland
| |
Collapse
|
5
|
Abstract
A limited number of peripheral targets generate pain. Inflammatory mediators can sensitize these. The review addresses targets acting exclusively or predominantly on sensory neurons, mediators involved in inflammation targeting sensory neurons, and mediators involved in a more general inflammatory process, of which an analgesic effect secondary to an anti-inflammatory effect can be expected. Different approaches to address these systems are discussed, including scavenging proinflammatory mediators, applying anti-inflammatory mediators, and inhibiting proinflammatory or facilitating anti-inflammatory receptors. New approaches are contrasted to established ones; the current stage of progress is mentioned, in particular considering whether there is data from a molecular and cellular level, from animals, or from human trials, including an early stage after a market release. An overview of publication activity is presented, considering a IuPhar/BPS-curated list of targets with restriction to pain-related publications, which was also used to identify topics.
Collapse
Affiliation(s)
- Cosmin I Ciotu
- Center of Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria
| | - Michael J M Fischer
- Center of Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria.
| |
Collapse
|
6
|
Wiley SZ, Sriram K, Salmerón C, Insel PA. GPR68: An Emerging Drug Target in Cancer. Int J Mol Sci 2019; 20:E559. [PMID: 30696114 PMCID: PMC6386835 DOI: 10.3390/ijms20030559] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/19/2022] Open
Abstract
GPR68 (or ovarian cancer G protein-coupled receptor 1, OGR1) is a proton-sensing G-protein-coupled receptor (GPCR) that responds to extracellular acidity and regulates a variety of cellular functions. Acidosis is considered a defining hallmark of the tumor microenvironment (TME). GPR68 expression is highly upregulated in numerous types of cancer. Emerging evidence has revealed that GPR68 may play crucial roles in tumor biology, including tumorigenesis, tumor growth, and metastasis. This review summarizes current knowledge regarding GPR68-its expression, regulation, signaling pathways, physiological roles, and functions it regulates in human cancers (including prostate, colon and pancreatic cancer, melanoma, medulloblastoma, and myelodysplastic syndrome). The findings provide evidence for GPR68 as a potentially novel therapeutic target but in addition, we note challenges in developing drugs that target GPR68.
Collapse
Affiliation(s)
- Shu Z Wiley
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Krishna Sriram
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Cristina Salmerón
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Paul A Insel
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
| |
Collapse
|
7
|
Häder DP, Hemmersbach R. Gravitaxis in Euglena. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 979:237-266. [DOI: 10.1007/978-3-319-54910-1_12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
8
|
Huang XP, Karpiak J, Kroeze WK, Zhu H, Chen X, Moy SS, Saddoris KA, Nikolova VD, Farrell MS, Wang S, Mangano TJ, Deshpande DA, Jiang A, Penn RB, Jin J, Koller BH, Kenakin T, Shoichet BK, Roth BL. Allosteric ligands for the pharmacologically dark receptors GPR68 and GPR65. Nature 2015; 527:477-83. [PMID: 26550826 DOI: 10.1038/nature15699] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 09/04/2015] [Indexed: 01/15/2023]
Abstract
At least 120 non-olfactory G-protein-coupled receptors in the human genome are 'orphans' for which endogenous ligands are unknown, and many have no selective ligands, hindering the determination of their biological functions and clinical relevance. Among these is GPR68, a proton receptor that lacks small molecule modulators for probing its biology. Using yeast-based screens against GPR68, here we identify the benzodiazepine drug lorazepam as a non-selective GPR68 positive allosteric modulator. More than 3,000 GPR68 homology models were refined to recognize lorazepam in a putative allosteric site. Docking 3.1 million molecules predicted new GPR68 modulators, many of which were confirmed in functional assays. One potent GPR68 modulator, ogerin, suppressed recall in fear conditioning in wild-type but not in GPR68-knockout mice. The same approach led to the discovery of allosteric agonists and negative allosteric modulators for GPR65. Combining physical and structure-based screening may be broadly useful for ligand discovery for understudied and orphan GPCRs.
Collapse
Affiliation(s)
- Xi-Ping Huang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA.,National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA
| | - Joel Karpiak
- Department of Pharmaceutical Chemistry, University of California at San Francisco, Byers Hall, 1700 4th Street, San Francisco, California 94158-2550, USA
| | - Wesley K Kroeze
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Hu Zhu
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Xin Chen
- Center for Integrative Chemical Biology and Drug Discovery (CICBDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7363, USA.,Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, USA
| | - Sheryl S Moy
- Department of Psychiatry and Carolina Institute for Developmental Disabilities (CIDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7146, USA
| | - Kara A Saddoris
- Department of Psychiatry and Carolina Institute for Developmental Disabilities (CIDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7146, USA
| | - Viktoriya D Nikolova
- Department of Psychiatry and Carolina Institute for Developmental Disabilities (CIDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7146, USA
| | - Martilias S Farrell
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Sheng Wang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Thomas J Mangano
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA.,National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA
| | - Deepak A Deshpande
- Center for Translational Medicine and Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Alice Jiang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA.,National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA
| | - Raymond B Penn
- Center for Translational Medicine and Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Jian Jin
- Center for Integrative Chemical Biology and Drug Discovery (CICBDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7363, USA.,Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, USA
| | - Beverly H Koller
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7264, USA
| | - Terry Kenakin
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Brian K Shoichet
- Department of Pharmaceutical Chemistry, University of California at San Francisco, Byers Hall, 1700 4th Street, San Francisco, California 94158-2550, USA
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA.,National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA.,Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, USA
| |
Collapse
|
9
|
Microenvironmental Influences on Metastasis Suppressor Expression and Function during a Metastatic Cell's Journey. CANCER MICROENVIRONMENT 2014; 7:117-31. [PMID: 24938990 DOI: 10.1007/s12307-014-0148-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 06/08/2014] [Indexed: 12/21/2022]
Abstract
Metastasis is the process of primary tumor cells breaking away and colonizing distant secondary sites. In order for a tumor cell growing in one microenvironment to travel to, and flourish in, a secondary environment, it must survive a series of events termed the metastatic cascade. Before departing the primary tumor, cells acquire genetic and epigenetic changes that endow them with properties not usually associated with related normal differentiated cells. Those cells also induce a subset of bone marrow-derived stem cells to mobilize and establish pre-metastatic niches [1]. Many tumor cells undergo epithelial-to-mesenchymal transition (EMT), where they transiently acquire morphologic changes, reduced requirements for cell-cell contact and become more invasive [2]. Invasive tumor cells eventually enter the circulatory (hematogenous) or lymphatic systems or travel across body cavities. In transit, tumor cells must resist anoikis, survive sheer forces and evade detection by the immune system. For blood-borne metastases, surviving cells then arrest or adhere to endothelial linings before either proliferating or extravasating. Eventually, tumor cells complete the process by proliferating to form a macroscopic mass [3].Up to 90 % of all cancer related morbidity and mortality can be attributed to metastasis. Surgery manages to ablate most primary tumors, especially when combined with chemotherapy and radiation. But if cells have disseminated, survival rates drop precipitously. While multiple parameters of the primary tumor are predictive of local or distant relapse, biopsies remain an imperfect science. The introduction of molecular and other biomarkers [4, 5] continue to improve the accuracy of prognosis. However, the invasive procedure introduces new complications for the patient. Likewise, the heterogeneity of any tumor population [3, 6, 7] means that sampling error (i.e., since it is impractical to examine the entire tumor) necessitates further improvements.In the case of breast cancer, for example, women diagnosed with stage I diseases (i.e., no evidence of invasion through a basement membrane) still have a ~30 % likelihood of developing distant metastases [8]. Many physicians and patients opt for additional chemotherapy in order to "mop up" cells that have disseminated and have the potential to grow into macroscopic metastases. This means that ~ 70 % of patients receive unnecessary therapy, which has undesirable side effects. Therefore, improving prognostic capability is highly desirable.Recent advances allow profiling of primary tumor DNA sequences and gene expression patterns to define a so-called metastatic signature [9-11], which can be predictive of patient outcome. However, the genetic changes that a tumor cell must undergo to survive the initial events of the metastatic cascade and colonize a second location belie a plasticity that may not be adequately captured in a sampling of heterogeneous tumors. In order to tailor or personalize patient treatments, a more accurate assessment of the genetic profile in the metastases is needed. Biopsy of each individual metastasis is not practical, safe, nor particularly cost-effective. In recent years, there has been a resurrection of the notion to do a 'liquid biopsy,' which essentially involves sampling of circulating tumor cells (CTC) and/or cell free nucleic acids (cfDNA, including microRNA (miRNA)) present in blood and lymph [12-16].The rationale for liquid biopsy is that tumors shed cells and/or genetic fragments into the circulation, theoretically making the blood representative of not only the primary tumor but also distant metastases. Logically, one would predict that the proportion of CTC and/or cfDNA would be proportionate to the likelihood of developing metastases [14]. While a linear relationship does not exist, the information within CTC or cfDNA is beginning to show great promise for enabling a global snapshot of the disease. However, the CTC and cfDNA are present at extremely low levels. Nonetheless, newer technologies capture enough material to enrich and sequence the patient's DNA or quantification of some biomarkers.Among the biomarkers showing great promise are metastasis suppressors which, by definition, block a tumor cell's ability to complete the metastatic process without prohibiting primary tumor growth [17]. Since the discovery of the first metastasis suppressor, Nm23, more than 30 have been functionally characterized. They function at various stages of the metastatic cascade, but their mechanisms of action, for the most part, remain ill-defined. Deciphering the molecular interactions of functional metastasis suppressors may provide insights for targeted therapies when these regulators cease to function and result in metastatic disease.In this brief review, we summarize what is known about the various metastasis suppressors and their functions at individual steps of the metastatic cascade (Table 1). Some of the subdivisions are rather arbitrary in nature, since many metastasis suppressors affect more than one step in the metastatic cascade. Nonetheless what emerges is a realization that metastasis suppressors are intimately associated with the microenvironments in which cancer cells find themselves [18].
Collapse
|
10
|
Mogi C, Nakakura T, Okajima F. Role of extracellular proton-sensing OGR1 in regulation of insulin secretion and pancreatic β-cell functions. Endocr J 2014; 61:101-10. [PMID: 24088601 DOI: 10.1507/endocrj.ej13-0380] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Insulin secretion with respect to pH environments has been investigated for a long time but its mechanism remains largely unknown. Extracellular pH is usually maintained at around 7.4 and, its change has been thought to occur in non-physiological situations. Acidification takes place under ischemic and inflammatory microenvironments, where stimulation of anaerobic glycolysis results in the production of lactic acid. In addition to ionotropic ion channels, such as transient receptor potential V1 (TRPV1) and acid-sensing ion channels (ASICs), metabotropic proton-sensing G protein-coupled receptors (GPCRs) have also been identified recently as proton-sensing machineries. While ionotropic ion channels usually sense strong acidic pH, proton-sensing GPCRs sense pH of 7.6 to 6.0 and have been shown to mediate a variety of biological actions in neutral and mildly acidic pH environments. Studies with receptor knockout mice have revealed that proton-sensing receptors, including ovarian cancer G protein-coupled receptor 1 (OGR1), a proton-sensing GPCRs, play a role in the regulation of insulin secretion and glucose metabolism under physiological conditions. Small molecule 3,5-disubstituted isoxazoles have recently been identified as OGR1 agonists working at neutral pH and have been shown to stimulate pancreatic β-cell differentiation and insulin synthesis. Thus, proton-sensing OGR1 may be an important player for insulin secretion and a potential target for improving β-cell function.
Collapse
Affiliation(s)
- Chihiro Mogi
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | | | | |
Collapse
|