301
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Koukourakis MI, Giatromanolaki A, Simopoulos C, Polychronidis A, Sivridis E. Lactate dehydrogenase 5 (LDH5) relates to up-regulated hypoxia inducible factor pathway and metastasis in colorectal cancer. Clin Exp Metastasis 2005; 22:25-30. [PMID: 16132575 DOI: 10.1007/s10585-005-2343-7] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Accepted: 02/04/2005] [Indexed: 12/20/2022]
Abstract
Lactate dehydrogenase 5 (LDH5) is one of the five LDH isoenzymes and, apparently, the most important for promoting anaerobic glycolysis. LDH5 is transcriptionally regulated by the hypoxia inducible factors (HIF) 1alpha and 2alpha. In this study, the possible aggressive advantages that colorectal tumours may gain from a high LDH5 content was investigated. To this end, 75 colorectal adenocarcinomas were studied immunohistochemically for the expression of LDH5, and the results were related to tumor differentiation, lymph node and distant metastases, the expression of HIF1alpha and HIF2alpha, vascular density (VD) and vascular endothelial growth factor (VEGF). A high LDH5 content was noted in 51 of 75 (68%) colorectal adenocarcinomas. The reactivity was nuclear and/or cytoplasmic. Nuclear LDH5 reactivity was correlated with lymph node involvement and distant metastases. There was a direct association between LDH5 up-regulation and HIF1alpha and HIF2alpha accumulation. HIF1alpha was linked with VEGF, VD and also with extramural invasion, nodal and distant metastases. It is concluded that a high LDH5 content in tumor cells is directly related to an up-regulated HIF pathway and is linked with an aggressive phenotype in colorectal adenocarcinomas.
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Affiliation(s)
- Michael I Koukourakis
- Department of Radiotherapy/Oncology, Democritus University of Thrace Medical School, 68100 Alexandroupolis, Greece.
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302
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Lu X, Qin W, Li J, Tan N, Pan D, Zhang H, Xie L, Yao G, Shu H, Yao M, Wan D, Gu J, Yang S. The growth and metastasis of human hepatocellular carcinoma xenografts are inhibited by small interfering RNA targeting to the subunit ATP6L of proton pump. Cancer Res 2005; 65:6843-9. [PMID: 16061667 DOI: 10.1158/0008-5472.can-04-3822] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Extracellular pH is usually low in solid tumors, in contrast to the approximately neutral intracellular pH. V-ATPase, which overly functions in some cancers with metastatic potential, plays an important role in maintaining neutral cytosolic pH, very acidic luminal pH, and acidic extracellular pH. ATP6L, the 16 kDa subunit of proton pump V-ATPase, can provide proton hydrophilic transmembrane path. In this study, ATP6L in a human hepatocellular carcinoma cell line with highly metastatic potential (HCCLM3) was knocked down using DNA vector-based small interfering RNA (siRNA) to suppress the metastasis. The expression of ATP6L in stable siRNA transfectants, designated as si-HCCLM3 cells, was inhibited by approximately 60%. The proton secretion and the intracellular pH recovery from NH4Cl-prepulsed acidification were inhibited in si-HCCLM3 cells. The invasion of the si-HCCLM3 cells was suppressed in vitro; simultaneously, the expressions of matrix metalloproteinase-2 and gelatinase activity were reduced. In vivo, at 35th day after implantation of the si-HCCLM3 xenografts into the livers in BalB/c (nu+/nu+) mice, the size of liver tumor tissues was dramatically smaller in siRNA group than in the controlled group. The most impressing effect of ATP6L siRNA is its striking reduction of the metastatic potential of HCCLM3 cells. In control, all eight mice had the intrahepatic metastasis and six of eight the pulmonary metastasis, whereas in ATP6L siRNA-treated group, three of eight had the intrahepatic metastasis and only one of eight the pulmonary metastasis. The results suggest that the inhibition of V-ATPase function via knockdown of ATP6L expression using RNA interfering technology can effectively retard the cancer growth and suppress the cancer metastasis by the decrease of proton extrusion and the down-regulation of gelatinase activity.
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Affiliation(s)
- Xiaodong Lu
- National Laboratory for Oncogenes and Related Genes, WHO Collaborating Center for Research on Cancer, Shanghai Cancer Institute, Shanghai, People's Republic of China
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303
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Titus MA, Gregory CW, Ford OH, Schell MJ, Maygarden SJ, Mohler JL. Steroid 5α-Reductase Isozymes I and II in Recurrent Prostate Cancer. Clin Cancer Res 2005; 11:4365-71. [PMID: 15958619 DOI: 10.1158/1078-0432.ccr-04-0738] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Prostate cancer recurs during androgen deprivation therapy despite reduced circulating androgens. We showed that recurrent prostate cancer tissue has testosterone levels similar to androgen-stimulated benign prostate, whereas dihydrotestosterone levels were reduced 82% to 1.45 nmol/L, sufficient for androgen receptor activation. The altered testosterone/dihydrotestosterone ratio in recurrent prostate cancer suggests loss of 5alpha-reducing capability. The aim of this study was to characterize steroid 5alpha-reductase isozymes I (S5alphaRI) and II (S5alphaRII) in prostate tissues. EXPERIMENTAL DESIGN A tissue microarray was constructed from 22 recurrent prostate cancer specimens and matched pairs of androgen-stimulated benign prostate and androgen-stimulated prostate cancer from 23 radical prostatectomy specimens. Immunoblots were constructed from eight recurrent prostate cancers, eight androgen-stimulated benign prostate, and eight androgen-stimulated prostate cancer specimens. Isozyme expression was examined in microarray sections and immunoblots using S5alphaRI and S5alphaRII polyclonal antibodies. Isozyme activities were measured in 12 recurrent prostate cancer, 12 androgen-stimulated benign prostate, and 12 androgen-stimulated prostate cancer specimens. RESULTS Nuclear immunostaining exhibited higher S5alphaRI expression than S5alphaRII in recurrent prostate cancer, androgen-stimulated benign prostate, and androgen-stimulated prostate cancers (P < 0.0001); mean expression was 125, 150, and 115 for S5alphaRI versus 10, 29, and 37 for S5alphaRII, respectively. Cytoplasmic immunostaining was moderate and similar for both isozymes in the three tissue types (P > 0.05). Immunoblots confirmed immunohistochemistry; S5alphaRI was expressed in recurrent prostate cancer specimens and S5alphaRII was not detected. The activity of S5alphaRI (114.4 pmol/mg epithelial protein/minute) was 3.7-fold higher than S5alphaRII (30.7 pmol/mg epithelial protein/minute) in recurrent prostate cancer specimens. CONCLUSIONS Expression levels and isozyme activity shifts from S5alphaRII toward S5alphaRI in recurrent prostate cancer. Dual inhibition of S5alphaRI and S5alphaRII should reduce dihydrotestosterone biosynthesis and may prevent or delay growth of recurrent prostate cancer.
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Affiliation(s)
- Mark A Titus
- Department of Pathology and Laboratory Medicine, Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7295, USA.
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304
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Smallbone K, Gavaghan DJ, Gatenby RA, Maini PK. The role of acidity in solid tumour growth and invasion. J Theor Biol 2005; 235:476-84. [PMID: 15935166 DOI: 10.1016/j.jtbi.2005.02.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Revised: 02/01/2005] [Accepted: 02/04/2005] [Indexed: 02/08/2023]
Abstract
Acidic pH is a common characteristic of human tumours. It has a significant impact on tumour progression and response to therapies. In this paper, we develop a simple model of three-dimensional tumour growth to examine the role of acidosis in the interaction between normal and tumour cell populations. Both vascular and avascular tumour dynamics are investigated, and a number of different behaviours are observed. Whilst an avascular tumour always proceeds to a benign steady state, a vascular tumour may display either benign or invasive dynamics, depending on the value of a critical parameter. Analysis of the model allows us to assess novel therapies directed towards changing the level of acidity within the tumour.
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Affiliation(s)
- Kieran Smallbone
- Centre for Mathematical Biology, Mathematical Institute, Oxford University, 24-29 St Giles', Oxford, OX1 3LB, UK.
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305
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Christou H, Bailey N, Kluger MS, Mitsialis SA, Kourembanas S. Extracellular acidosis induces heme oxygenase-1 expression in vascular smooth muscle cells. Am J Physiol Heart Circ Physiol 2005; 288:H2647-52. [PMID: 15681695 DOI: 10.1152/ajpheart.00937.2004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extracellular acidosis (EA) has profound effects on vascular homeostasis, including vascular bed-specific alterations in vascular tone. Regulation of gene expression by EA has been observed in a variety of cells including vascular endothelial cells. Whether EA regulates gene expression in vascular smooth muscle cells (VSMCs) is not known. Heme oxygenase (HO)-1 is expressed in vascular cells, and its expression is regulated by cellular stressors such as heat, radiation, and hypoxia. Increased HO-1 expression in VSMCs leads to increased production of CO and its second messenger cGMP, which are important regulators of vascular tone and paracrine interactions in the vasculature. We examined whether EA regulates the expression of HO-1 in VSMCs. Exposure of VSMCs to acidic medium (pH 6.8) significantly increased HO-1 mRNA and protein compared with exposure to medium of physiological pH (pH 7.4). The acidic induction of HO-1 expression was time dependent and involved both transcriptional activation of the HO-1 gene and enhanced stability of HO-1 mRNA. Nitric oxide did not appear to mediate this response. We conclude that HO-1 is transcriptionally and posttranscriptionally upregulated by EA in VSMCs. This induction is time dependent and reversible. We speculate that EA, as an important tissue and cellular stressor for VSMCs, may elicit changes in gene expression patterns that contribute to the maintenance or disruption of vascular homeostasis.
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Affiliation(s)
- Helen Christou
- Div. of Newborn Medicine, Children's Hospital, 300 Longwood Ave., Enders 9, Boston, MA 02115, USA.
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306
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Kivelä AJ, Kivelä J, Saarnio J, Parkkila S. Carbonic anhydrases in normal gastrointestinal tract and gastrointestinal tumours. World J Gastroenterol 2005; 11:155-63. [PMID: 15633208 PMCID: PMC4205394 DOI: 10.3748/wjg.v11.i2.155] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Carbonic anhydrases (CAs) catalyse the hydration of CO2 to bicarbonate at physiological pH. This chemical interconversion is crucial since HCO3- is the substrate for several biosynthetic reactions. This review is focused on the distribution and role of CA isoenzymes in both normal and pathological gastrointestinal (GI) tract tissues. It has been known for many years that CAs are widely present in the GI tract and play important roles in several physiological functions such as production of saliva, gastric acid, bile, and pancreatic juice as well as in absorption of salt and water in intestine. New information suggests that these enzymes participate in several processes that were not envisioned earlier. Especially, the recent reports on plasma membrane-bound isoenzymes IX and XII have raised considerable interest since they were reported to participate in cancer invasion and spread. They are induced by tumour hypoxia and may also play a role in von Hippel-Lindau (VHL)-mediated carcinogenesis.
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Affiliation(s)
- Antti-J Kivelä
- Department of Anatomy and Cell Biology, University of Oulu, Finland.
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307
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Svastová E, Hulíková A, Rafajová M, Zat'ovicová M, Gibadulinová A, Casini A, Cecchi A, Scozzafava A, Supuran CT, Pastorek J, Pastoreková S. Hypoxia activates the capacity of tumor-associated carbonic anhydrase IX to acidify extracellular pH. FEBS Lett 2005; 577:439-45. [PMID: 15556624 DOI: 10.1016/j.febslet.2004.10.043] [Citation(s) in RCA: 567] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 10/13/2004] [Accepted: 10/17/2004] [Indexed: 12/18/2022]
Abstract
Acidic extracellular pH (pHe) is a typical attribute of a tumor microenvironment, which has an impact on cancer development and treatment outcome. It was believed to result from an accumulation of lactic acid excessively produced by glycolysis. However, metabolic profiles of glycolysis-impaired tumors have revealed that CO2 is a significant source of acidity, thereby indicating a contribution of carbonic anhydrase (CA). The tumor-associated CA IX isoform is the best candidate, because its extracellular enzyme domain is highly active, expression is induced by hypoxia and correlates with poor prognosis. This study provides the first evidence for the role of CA IX in the control of pHe. We show that CA IX can acidify the pH of the culture medium in hypoxia but not in normoxia. This acidification can be perturbed by deletion of the enzyme active site and inhibited by CA IX-selective sulfonamides, which bind only to hypoxic cells containing CA IX. Our findings suggest that hypoxia regulates both expression and activity of CA IX in order to enhance the extracellular acidification, which may have important implications for tumor progression.
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Affiliation(s)
- Eliska Svastová
- Centre of Molecular Medicine, Institute of Virology, Slovak Academy of Sciences, Dúbravská cesta 9, 845 05 Bratislava, Slovak Republic
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308
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Raghunand N, Gatenby RA, Gillies RJ. Microenvironmental and cellular consequences of altered blood flow in tumours. Br J Radiol 2004; 76 Spec No 1:S11-22. [PMID: 15456710 DOI: 10.1259/bjr/12913493] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Tumour angiogenesis is triggered by various signals characteristic of the tumour microenvironment, including low oxygen tension, low extracellular pH and low glucose concentration. Tumour microvasculature is chaotic, producing perfusion heterogeneities which can be visualized by MRI and other modalities. Inefficient perfusion in tumours produces regions of transient and chronic hypoxia. Tumour hypoxia is associated with adverse clinical outcomes and reduced patient survival. Hypoxia may be a factor in activation of extracellular matrix-degrading proteases, and some studies have correlated primary tumour hypoxia with likelihood of tumour cell dissemination. Exposure to hypoxia either induces or selects for cells that are hyperglycolytic, and this in turn produces local acidosis which is also a common feature of solid tumours. Increased glucose uptake in hyperglycolyzing tumour cells is the basis of lesion-visualization in positron emission tomography using 18F-fluorodeoxyglucose. Tumour acidity can reduce the effectiveness of weak-base drugs, but can be exploited to increase the anti-tumour activity of weak-acid chemotherapeutics. Evidence linking tumour acidity with increased activity of several extracellular matrix-degrading enzyme systems is examined. High levels of lactate, another end-product of glycolysis, in primary lesions have been correlated with increased likelihood of metastasis. In the numerous studies correlating hypoxia, acidity and lactate with metastasis, the direction of the causality has not been adequately established. We hypothesize that adoption of a hyperglycolytic phenotype is a necessary feature of carcinogenesis itself, and confers a survival and proliferative advantage to tumour cells over surrounding normal cells. Empirical evidence supporting this "acid-mediated tumour invasion" model is discussed.
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Affiliation(s)
- N Raghunand
- Department of Biochemistry and Molecular Biophysics, University of Arizona Health Sciences Center, Tucson, AZ 85724-5024, USA
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309
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Pastorekova S, Parkkila S, Pastorek J, Supuran CT. Carbonic anhydrases: current state of the art, therapeutic applications and future prospects. J Enzyme Inhib Med Chem 2004; 19:199-229. [PMID: 15499993 DOI: 10.1080/14756360410001689540] [Citation(s) in RCA: 524] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Carbonic anhydrases (CAs, EC 4.2.1.1) are wide-spread enzymes, present in mammals in at least 14 different isoforms. Some of these isozymes are cytosolic (CA I, CA II, CA III, CA VII, CA XIII), others are membrane-bound (CA IV, CA IX, CA XII and CA XIV), CA V is mitochondrial and CA VI is secreted in the saliva and milk. Three cytosolic acatalytic forms are also known (CARP VIII, CARP X and CARP XI). The catalytically active isoforms, which play important physiological and patho-physiological functions, are strongly inhibited by aromatic and heterocyclic sulfonamides. The catalytic and inhibition mechanisms of these enzymes are understood in great detail, and this greatly helped the design of potent inhibitors, some of which possess important clinical applications. The use of such CA inhibitors (CAIs) as antiglaucoma drugs are discussed in detail, together with the recent developments that led to isozyme-specific and organ-selective inhibitors. A recent discovery is connected with the involvement of CAs and their sulfonamide inhibitors in cancer: many potent CAIs were shown to inhibit the growth of several tumor cell lines in vitro and in vivo, thus constituting interesting leads for developing novel antitumor therapies. Future prospects for drug design of inhibitors of these ubiquitous enzymes are dealt with. Although activation of CAs has been a controversial issue for some time, recent kinetic, spectroscopic and X-ray crystallographic experiments offered an explanation of this phenomenon, based on the catalytic mechanism. It has been demonstrated recently, that molecules that act as carbonic anhydrase activators (CAAs) bind at the entrance of the enzyme active site participating in facilitated proton transfer processes between the active site and the reaction medium. In addition to CA II-activator adducts, X-ray crystallographic studies have been also reported for ternary complexes of this isozyme with activators and anion (azide) inhibitors. Structure-activity correlations for diverse classes of activators is discussed for the isozymes for which the phenomenon has been studied, i.e., CA I, II, III and IV. The possible physiological relevance of CA activation/inhibition is also addressed, together with recent pharmacological/ biomedical applications of such compounds in different fields of life sciences.
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Affiliation(s)
- Silvia Pastorekova
- Centre of Molecular Medicine, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 842 45 Bratislava, Slovak Republic
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310
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Abstract
If carcinogenesis occurs by somatic evolution, then common components of the cancer phenotype result from active selection and must, therefore, confer a significant growth advantage. A near-universal property of primary and metastatic cancers is upregulation of glycolysis, resulting in increased glucose consumption, which can be observed with clinical tumour imaging. We propose that persistent metabolism of glucose to lactate even in aerobic conditions is an adaptation to intermittent hypoxia in pre-malignant lesions. However, upregulation of glycolysis leads to microenvironmental acidosis requiring evolution to phenotypes resistant to acid-induced cell toxicity. Subsequent cell populations with upregulated glycolysis and acid resistance have a powerful growth advantage, which promotes unconstrained proliferation and invasion.
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Affiliation(s)
- Robert A Gatenby
- Department of Radiology, University of Arizona, Tucson, Arizona 85721, USA.
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311
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Robertson N, Potter C, Harris AL. Role of carbonic anhydrase IX in human tumor cell growth, survival, and invasion. Cancer Res 2004; 64:6160-5. [PMID: 15342400 DOI: 10.1158/0008-5472.can-03-2224] [Citation(s) in RCA: 232] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Carbonic anhydrase IX (CAIX) is a membrane-associated carbonic anhydrase (CA), strongly induced by hypoxia. CAIX is overexpressed in a variety of tumor types and associated with increased metastasis and poor prognosis. An inhibitor of CAs, acetazolamide has been reported to inhibit invasion. We used RNA interference (RNAi) to examine the function of CAIX in MDA468 and MDA231 breast carcinoma cells, which express high levels of CAIX under hypoxia. Hypoxia-induced CA activity was completely blocked by specific RNAi (P < 0.01). RNAi-treated cells showed growth delay in dense monolayer culture and a 50% reduction in clonogenic survival under hypoxia. In the MDA468 cells, there was no effect of RNAi treatment on invasion. In a cell line that did not induce CAIX under hypoxia, RT112, we found no effect on the ability of cells transfected with CAIX to invade or migrate. Thus, CAIX plays an important role in the growth and survival of tumor cells under normoxia and hypoxia, making it a potential target for cancer therapy, but is not involved in invasion.
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Affiliation(s)
- Naomi Robertson
- Cancer Research UK, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, United Kingdom
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312
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Dewhirst MW, Richardson R, Cardenas-Navia I, Cao Y. The relationship between the tumor physiologic microenvironment and angiogenesis. Hematol Oncol Clin North Am 2004; 18:973-90, vii. [PMID: 15474330 DOI: 10.1016/j.hoc.2004.06.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This article examines the pathophysiology of tumors, with an emphasis on how these features influence angiogenesis in tumors.
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Affiliation(s)
- Mark W Dewhirst
- Department of Radiation Oncology, Duke University Medical Center, Room 201, Medical Science Research Building, Research Drive, Box 3455, Durham, NC 27710, USA.
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313
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Rojas JD, Sennoune SR, Maiti D, Martínez GM, Bakunts K, Wesson DE, Martínez-Zaguilán R. Plasmalemmal V-H+-ATPases regulate intracellular pH in human lung microvascular endothelial cells. Biochem Biophys Res Commun 2004; 320:1123-32. [PMID: 15249206 DOI: 10.1016/j.bbrc.2004.06.068] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Indexed: 11/21/2022]
Abstract
The lung endothelium layer is exposed to continuous CO(2) transit which exposes the endothelium to a substantial acid load that could be detrimental to cell function. The Na(+)/H(+) exchanger and HCO(3)(-)-dependent H(+)-transporting mechanisms regulate intracellular pH (pH(cyt)) in most cells. Cells that cope with high acid loads might require additional primary energy-dependent mechanisms. V-H(+)-ATPases localized at the plasma membranes (pmV-ATPases) have emerged as a novel pH regulatory system. We hypothesized that human lung microvascular endothelial (HLMVE) cells use pmV-ATPases, in addition to Na(+)/H(+) exchanger and HCO(3)(-)-based H(+)-transporting mechanisms, to maintain pH(cyt) homeostasis. Immunocytochemical studies revealed V-H(+)-ATPase at the plasma membrane, in addition to the predicted distribution in vacuolar compartments. Acid-loaded HLMVE cells exhibited proton fluxes in the absence of Na(+) and HCO(3)(-) that were similar to those observed in the presence of either Na(+), or Na(+) and HCO(3)(-). The Na(+)- and HCO(3)(-)-independent pH(cyt) recovery was inhibited by bafilomycin A(1), a V-H(+)-ATPase inhibitor. These studies show a Na(+)- and HCO(3)(-)-independent pH(cyt) regulatory mechanism in HLMVE cells that is mediated by pmV-ATPases.
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Affiliation(s)
- José D Rojas
- Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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314
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Kalliomäki T, Hill RP. Effects of tumour acidification with glucose+MIBG on the spontaneous metastatic potential of two murine cell lines. Br J Cancer 2004; 90:1842-9. [PMID: 15150590 PMCID: PMC2409743 DOI: 10.1038/sj.bjc.6601766] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In addition to hypoxia, acidic extracellular pH (pHe) is recognised as one of the microenvironmental characteristics of solid tumours. A number of studies have examined ways to increase tumour acidity in order to improve tumour-specific targeting of certain drugs and the effectiveness of hyperthermia. However, previous data have shown that exposure of murine tumour cells to acid conditions in culture can enhance their metastatic potential when injected subsequently into mice, raising the concern that deliberate tumour acidification might increase the probability of metastasis. In this study, we examined the effects of in vivo tumour acidification and hypoxia on the spontaneous metastatic potential of the murine KHT-C fibrosarcoma and B16F1 melanoma cell lines. A tumour-specific increase in extracellular acidity, demonstrated by measurements with pH electrodes, was achieved by daily intraperitoneal injections of meta-iodo-benzylguanidine (MIBG) and/or glucose. This method of tumour acidification during tumour growth did not significantly enhance the spontaneous metastatic potential of the two murine cell lines.
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Affiliation(s)
- T Kalliomäki
- Experimental Therapeutics Division, Ontario Cancer Institute/Princess Margaret Hospital, Toronto, Ontario, Canada M5G 2M9
- Department of Medical Biophysics
| | - R P Hill
- Experimental Therapeutics Division, Ontario Cancer Institute/Princess Margaret Hospital, Toronto, Ontario, Canada M5G 2M9
- Department of Medical Biophysics
- Department of Radiation Oncology, University of Toronto, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9
- Experimental Therapeutics Division, Ontario Cancer Institute/Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario, Canada, M5G 2M9. E-mail:
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315
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Sufan RI, Jewett MAS, Ohh M. The role of von Hippel-Lindau tumor suppressor protein and hypoxia in renal clear cell carcinoma. Am J Physiol Renal Physiol 2004; 287:F1-6. [PMID: 15180922 DOI: 10.1152/ajprenal.00424.2003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The majority of kidney cancers are caused by the mutation of the von Hippel-Lindau (VHL) tumor suppressor gene. VHL protein (pVHL) is part of an E3 ubiquitin ligase complex called VEC that is composed of elongin B, elongin C, cullin 2, NEDD8, and Rbx1. VEC targets a hypoxia-inducible factor (HIF) transcription factor for ubiquitin-mediated destruction selectively in the presence of oxygen. In the absence of wild-type pVHL, as in VHL patients or in the majority of sporadic clear cell renal cell carcinomas, HIF-responsive genes are inappropriately activated even under normoxia. Recent insights into the molecular mechanisms regulating the function of pVHL, and thereby HIF, in the context of kidney cancer are the focus of this review.
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Affiliation(s)
- Roxana I Sufan
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8
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316
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Höpfl G, Ogunshola O, Gassmann M. HIFs and tumors--causes and consequences. Am J Physiol Regul Integr Comp Physiol 2004; 286:R608-23. [PMID: 15003941 DOI: 10.1152/ajpregu.00538.2003] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
For most organisms oxygen is essential fo life. When oxygen levels drop below those required to maintain the minimum physiological oxygen requirement of an organism or tissue it is termed hypoxia. To counter act possible deleterious effects of such a state, an immediate molecular response is initiated causing adaptation responses aimed at cell survival. This response is mediated by the hypoxia-inducible factor-1 (HIF-1), which is a heterodimer consisting of an alpha- and a beta-subunit. HIF-1 alpha protein is stabilized under hypoxic conditions and therefore confers selectivity to this response. Hypoxia is characteristic of tumors, mainly because of impaired blood supply resulting from abnormal growth. Over the past few years enormous progress has been made in the attempt to understand how the activation of the physiological response to hypoxia influences neoplastic growth. In this review some aspects of HIF-1 pathway activation in tumors and the consequences for pathophysiology and treatment of neoplasia are discussed.
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Affiliation(s)
- Gisele Höpfl
- Institute of Veterinary Physiology, University of Zürich, Winterthurerstrasse 260, CH-8057 Zürich, Switzerland
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317
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Sennoune SR, Bakunts K, Martínez GM, Chua-Tuan JL, Kebir Y, Attaya MN, Martínez-Zaguilán R. Vacuolar H+-ATPase in human breast cancer cells with distinct metastatic potential: distribution and functional activity. Am J Physiol Cell Physiol 2004; 286:C1443-52. [PMID: 14761893 DOI: 10.1152/ajpcell.00407.2003] [Citation(s) in RCA: 269] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tumor cells thrive in a hypoxic microenvironment with an acidic extracellular pH. To survive in this harsh environment, tumor cells must exhibit a dynamic cytosolic pH regulatory system. We hypothesize that vacuolar H(+)-ATPases (V-ATPases) that normally reside in acidic organelles are also located at the cell surface, thus regulating cytosolic pH and exacerbating the migratory ability of metastatic cells. Immunocytochemical data revealed for the first time that V-ATPase is located at the plasma membrane of human breast cancer cells: prominent in the highly metastatic and inconspicuous in the lowly metastatic cells. The V-ATPase activities in isolated plasma membranes were greater in highly than in lowly metastatic cells. The proton fluxes via V-ATPase evaluated by fluorescence spectroscopy in living cells were greater in highly than in lowly metastatic cells. Interestingly, lowly metastatic cells preferentially used the ubiquitous Na(+)/H(+) exchanger and HCO(3)(-)-based H(+)-transporting mechanisms, whereas highly metastatic cells used plasma membrane V-ATPases. The highly metastatic cells were more invasive and migratory than the lowly metastatic cells. V-ATPase inhibitors decreased the invasion and migration in the highly metastatic cells. Altogether, these data indicate that V-ATPases located at the plasma membrane are involved in the acquisition of a more metastatic phenotype.
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Affiliation(s)
- Souad R Sennoune
- Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, Texas 79430-6551, USA.
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318
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Henning T, Kraus M, Brischwein M, Otto AM, Wolf B. Relevance of tumor microenvironment for progression, therapy and drug development. Anticancer Drugs 2004; 15:7-14. [PMID: 15090737 DOI: 10.1097/00001813-200401000-00002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Tumor interstitium exhibits a microenvironment that differs from corresponding normal tissues. Tumor phenotype shows, for example, an elevated intracellular pH (pHi), a lowered extracellular pH (pHe), a low oxygen concentration and low glucose levels. These differences are caused by cell biological (so called intrinsic) factors, e.g. a higher acidification rate, as well as by more systemic (extrinsic) factors, e.g. poor tumor vascularization. They represent important factors for invasiveness, immune suppression and proliferation, and they imply possibilities for diagnosis, prognosis and therapy. We have developed an experimental data-based computer model, which has simulated the potential role of metabolic effects on tumor progression. We show an experiment on cellular metabolism demonstrating the immunosuppressive impact of low pHe on peripheral blood mononuclear cells. Finally, we review important findings on the tumor microenvironment leading to possibilities for therapy which are currently evolving and which promise higher effectiveness for cancer therapy.
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Affiliation(s)
- Tobias Henning
- Heinz-Nixdorf-Lehrstuhl für Medizinische Elektronik, Technische Universität München, München, Germany
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319
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Yamada H, Yamazaki S, Moriyama N, Hara C, Horita S, Enomoto Y, Kudo A, Kawakami H, Tanaka Y, Fujita T, Seki G. Localization of NBC-1 variants in human kidney and renal cell carcinoma. Biochem Biophys Res Commun 2003; 310:1213-8. [PMID: 14559244 DOI: 10.1016/j.bbrc.2003.09.147] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Na(+)-HCO(3)(-) cotransporter (NBC-1) plays a major role in bicarbonate absorption from proximal tubules. However, which NBC-1 variant mediates proximal bicarbonate absorption has not been definitely determined. Moreover, the localization of this cotransporter in human kidney and renal cell carcinoma (RCC) tissues has not been clarified. To clarify these issues, immunohistochemical analysis was performed using the specific antibodies against kidney type (kNBC-1) and pancreatic type (pNBC-1) transporters. In Western blot analysis the expression of kNBC-1 but not of pNBC-1 was detected in both normal human kidney and RCC tissues. In immunofluorescence analysis on normal renal tissues the anti-kNBC-1 antibody strongly and exclusively labeled the basolateral membranes of proximal tubules, which was confirmed by electron microscopic observation. In RCC cells, the anti-kNBC-1 antibody labeled both plasma membranes and intracellular organelles. The labeling by anti-pNBC-1 antibody was not detected in both normal kidney and RCC tissues. These results indicate that kNBC-1 is the dominant variant that mediates bicarbonate absorption from human renal proximal tubules. They also suggest that NBC-1 may have distinct roles in cancer cells.
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Affiliation(s)
- Hideomi Yamada
- Department of Internal Medicine, Faculty of Medicine, Tokyo University, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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320
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Glunde K, Guggino SE, Solaiyappan M, Pathak AP, Ichikawa Y, Bhujwalla ZM. Extracellular acidification alters lysosomal trafficking in human breast cancer cells. Neoplasia 2003; 5:533-45. [PMID: 14965446 PMCID: PMC1502575 DOI: 10.1016/s1476-5586(03)80037-4] [Citation(s) in RCA: 211] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2003] [Revised: 10/06/2003] [Accepted: 10/08/2003] [Indexed: 11/24/2022]
Abstract
Cancer cells invade by secreting degradative enzymes, which are sequestered in lysosomal vesicles. In this study, the impact of an acidic extracellular environment on lysosome size, number, and distance from the nucleus in human mammary epithelial cells (HMECs) and breast cancer cells of different degrees of malignancy was characterized because the physiological microenvironment of tumors is frequently characterized by extracellular acidity. An acidic extracellular pH (pH(e)) resulted in a distinct shift of lysosomes from the perinuclear region to the cell periphery irrespective of the HMECs' degree of malignancy. With decreasing pH, larger lysosomal vesicles were observed more frequently in highly metastatic breast cancer cells, whereas smaller lysosomes were observed in poorly metastatic breast cancer cells and HMECs. The number of lysosomes decreased with acidic pH values. The displacement of lysosomes to the cell periphery driven by extracellular acidosis may facilitate exocytosis of these lysosomes and increase secretion of degradative enzymes. Filopodia formations, which were observed more frequently in highly metastatic breast cancer cells maintained at acidic pH(e), may also contribute to invasion.
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Affiliation(s)
- Kristine Glunde
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sandra E. Guggino
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Meiyappan Solaiyappan
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Arvind P. Pathak
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yoshitaka Ichikawa
- Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zaver M. Bhujwalla
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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321
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Oliver VK, Patton AM, Desai S, Lorang D, Libutti SK, Kohn EC. Regulation of the pro-angiogenic microenvironment by carboxyamido-triazole. J Cell Physiol 2003; 197:139-48. [PMID: 12942550 DOI: 10.1002/jcp.10350] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Anti-angiogenic agents regulate tumor growth by inhibiting endothelial cell proliferation and invasion. Carboxyamido-triazole (CAI), an inhibitor of non-voltage-operated calcium entry and calcium influx-mediated pathways, has angiogenesis and invasion inhibitory activity. We hypothesized that CAI may express its anti-angiogenic effects through negative regulation of pro-angiogenic cytokine production and/or function. In vivo, orally administered CAI prevented A2058 human melanoma xenograft growth and concomitantly resulted in a marked reduction in circulating vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). In vitro, A2058 cell secretion of VEGF was inhibited by CAI treatment under limiting micronutrient conditions that approximate the tumor microenvironment, media restriction, and acidification to pH 6.8 (P=0.0003 and P=0.0006, respectively). VEGF and HIF-1alpha message and protein were also reduced by CAI treatment. Oral CAI treatment reduced vascular ingrowth in vivo into VEGF-containing Matrigel plugs. Commensurate with those findings, human umbilical vein endothelial cell (HUVEC) migration towards VEGF was reduced below background by exposure to CAI in the migration chamber (P<0.0001). An 88% reduction in circulating IL-8 concentration was measured in CAI-treated animals. However, IL-8 protein secretion and gene expression were increased by CAI treatment in culture (P< or =0.01), where CAI caused a dose-dependent acidification of the culture milieu (P< or =0.005). This paradox suggests that IL-8 production in vitro may be more sensitive to ambient pH than cytosolic calcium. These observations suggest that CAI inhibition of tumor cell VEGF production and endothelial cell response to VEGF results in disruption of signaling between the tumor and its microenvironment, causing a net anti-angiogenic effect.
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Affiliation(s)
- Vyta Kulpa Oliver
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-1500, USA
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322
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Koukourakis MI, Giatromanolaki A, Sivridis E, Bougioukas G, Didilis V, Gatter KC, Harris AL. Lactate dehydrogenase-5 (LDH-5) overexpression in non-small-cell lung cancer tissues is linked to tumour hypoxia, angiogenic factor production and poor prognosis. Br J Cancer 2003; 89:877-85. [PMID: 12942121 PMCID: PMC2394471 DOI: 10.1038/sj.bjc.6601205] [Citation(s) in RCA: 299] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lactate dehydrogenase-5 (LDH-5) catalyses the reversible transformation of pyruvate to lactate, having a principal position in the anaerobic cellular metabolism. Induction of LDH-5 occurs during hypoxia and LDH-5 transcription is directly regulated by the hypoxia-inducible factor 1 (HIF1). Serum LDH levels have been correlated with poor prognosis and resistance to chemotherapy and radiotherapy in various neoplastic diseases. The expression, however, of LDH in tumours has never been investigated in the past. In the present study, we established an immunohistochemical method to evaluate the LDH-5 overexpression in tumours, using two novel antibodies raised against the rat muscle LDH-5 and the human LDH-5 (Abcam, UK). The subcellular patterns of expression in cancer cells were mixed nuclear and cytoplasmic. In direct contrast to cancer cells, stromal fibroblasts were reactive for LDH-5 only in a minority of cases. Serum LDH, although positively correlated with, does not reliably reflect the intratumoral LDH-5 status. Lactate dehydrogenase-5 overexpression was directly related to HIF1alpha and 2alpha, but not with the carbonic anhydrase 9 expression. Patients with tumours bearing high LDH-5 expression had a poor prognosis. Tumours with simultaneous LDH-5 and HIF1alpha (or HIF2alpha) overexpression, indicative of a functional HIF pathway, had a particularly aggressive behaviour. It is concluded that overexpression of LDH-5 is a common event in non-small-cell lung cancer, can be easily assessed in paraffin-embedded material and provides important prognostic information, particularly when combined with other endogenous markers of hypoxia and acidity.
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Affiliation(s)
- M I Koukourakis
- Department of Radiotherapy/Oncology, Democritus University of Thrace, Alexandroupolis 68100, Greece.
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323
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Abstract
The carbonic anhydrases (CAs) comprise a family of evolutionarily ancient enzymes found ubiquitously in nature. They have important roles in facilitating transport of carbon dioxide and protons in the intracellular space, across biological membranes and in the unstirred layers of the extracellular space. The tumour-associated isoenzymes, CAIX and CAXII, are expressed in a wide variety of malignancies and appear to be tightly regulated by microenvironmental hypoxia. CAIX expression is linked to poor prognosis in a number of human tumours, and may be a marker of aggressive malignant phenotype and a mechanism of progression. Inhibitors of CA may inhibit tumour growth and invasion, with consequent therapeutic potential.
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Affiliation(s)
- C P S Potter
- Cancer Research UKGrowth Factor Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - A L Harris
- Cancer Research UKGrowth Factor Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, UK
- Cancer Research UKGrowth Factor Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, UK. E-mail:
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324
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Abstract
The presence of activated oncogenes and/or inactivated tumor suppressor genes may result in constitutive activation of multiple transcription factors. This may be especially true in the early stages of tumor development. At advanced stages, however, uncontrolled tumor growth and the consequent development of a stress microenvironment, such as hypoxia, acidosis, and free radical overproduction, may further alter the activity of these transcription factors. Abnormal activation of and interplay between these factors lead to aberrant expression of multiple metastasis-related proteins and confer a tremendous survival and growth advantage to emerging metastatic variants. Understanding the expression and regulation of these molecules may shed more light on the biology of cancer metastasis as well as suggest new preventive and therapeutic approaches.
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Affiliation(s)
- Keping Xie
- Department of Gastrointestinal Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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325
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Schornack PA, Gillies RJ. Contributions of cell metabolism and H+ diffusion to the acidic pH of tumors. Neoplasia 2003; 5:135-45. [PMID: 12659686 PMCID: PMC1502399 DOI: 10.1016/s1476-5586(03)80005-2] [Citation(s) in RCA: 187] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2002] [Revised: 11/27/2002] [Accepted: 12/02/2002] [Indexed: 11/22/2022]
Abstract
The tumor microenvironment is hypoxic and acidic. These conditions have a significant impact on tumor progression and response to therapies. There is strong evidence that tumor hypoxia results from inefficient perfusion due to a chaotic vasculature. Consequently, some tumor regions are well oxygenated and others are hypoxic. It is commonly believed that hypoxic regions are acidic due to a stimulation of glycolysis through hypoxia, yet this is not yet demonstrated. The current study investigates the causes of tumor acidity by determining acid production rates and the mechanism of diffusion for H(+) equivalents through model systems. Two breast cancer cell lines were investigated with divergent metabolic profiles: nonmetastatic MCF-7/s and highly metastatic MDA-mb-435 cells. Glycolysis and acid production are inhibited by oxygen in MCF-7/s cells, but not in MDA-mb-435 cells. Tumors of MDA-mb-435 cells are significantly more acidic than are tumors of MCF-7/s cells, suggesting that tumor acidity is primarily caused by endogenous metabolism, and not the lack of oxygen. Metabolically produced protons are shown to diffuse in association with mobile buffers, in concordance with previous studies. The metabolic and diffusion data were analyzed using a reaction-diffusion model to demonstrate that the consequent pH profiles conform well to measured pH values for tumors of these two cell lines.
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Affiliation(s)
- Paul A Schornack
- Department of Biochemistry and Molecular Biophysics, Arizona Cancer Center, Arizona Health Sciences Center, University of Arizona, Tucson, AZ 85724-5024, USA
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326
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McSheehy PMJ, Troy H, Kelland LR, Judson IR, Leach MO, Griffiths JR. Increased tumour extracellular pH induced by Bafilomycin A1 inhibits tumour growth and mitosis in vivo and alters 5-fluorouracil pharmacokinetics. Eur J Cancer 2003; 39:532-40. [PMID: 12751386 DOI: 10.1016/s0959-8049(02)00671-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The aim was to determine if a specific inhibitor of vacuolar H(+)-ATPases (V-ATPases), Bafilomycin A1 (BFM), could increase the low extracellular pH (pHe) typical of solid tumours and thus inhibit their growth in vivo. BFM inhibited the proliferation of various human cells and rat pituitary GH3 tumour cells in vitro (IC50: 2.5-19.2 nM), and flow cytometry on GH3 cells showed a marked increase in S and G2M phases after 16-48 h, but no evidence of increased apoptosis. BFM caused significant inhibition of GH3 xenograft growth, and histomorphometry showed a 30% decrease in mitosis but no change in apoptosis. 31P-magnetic resonance spectroscopy (MRS) in vivo of GH3 xenografts showed that BFM increased pHe, but did not affect pHi, resulting in a decrease in the negative pH gradient (-delta pH). BFM decreased lactate formation suggesting a reduction in glycolysis. We suggest that BFM reduces extracellular H(+)-transport by inhibition of V-ATPases leading to an increase in pHe and decreased glycolysis, and thus reduced tumour cell proliferation. 19F-MRS in vivo showed that a smaller -delta pH was associated with decreased retention of 5-fluorouracil (5FU) which was consistent with our previous data in vivo implying the -delta pH controls tumour retention of 5 FU.
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Affiliation(s)
- P M J McSheehy
- Cancer Research UK Biomedical Magnetic Resonance Research Group, Department of Biochemistry and Immunology, St. George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK.
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327
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Fidler IJ, Yoneda J, Herrera C, Wood J, Xu L. Specific keynote: molecular determinants of angiogenesis in ovarian cancer. Gynecol Oncol 2003; 88:S29-36; discussion S37-42. [PMID: 12586082 DOI: 10.1006/gyno.2002.6680] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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328
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Gillies RJ, Raghunand N, Karczmar GS, Bhujwalla ZM. MRI of the tumor microenvironment. J Magn Reson Imaging 2002; 16:430-50. [PMID: 12353258 DOI: 10.1002/jmri.10181] [Citation(s) in RCA: 418] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The microenvironment within tumors is significantly different from that in normal tissues. A major difference is seen in the chaotic vasculature of tumors, which results in unbalanced blood supply and significant perfusion heterogeneities. As a consequence, many regions within tumors are transiently or chronically hypoxic. This exacerbates tumor cells' natural tendency to overproduce acids, resulting in very acidic pH values. The hypoxia and acidity of tumors have important consequences for antitumor therapy and can contribute to the progression of tumors to a more aggressive metastatic phenotype. Over the past decade, techniques have emerged that allow the interrogation of the tumor microenvironment with high resolution and molecularly specific probes. Techniques are available to interrogate perfusion, vascular distribution, pH, and pO(2) nondestructively in living tissues with relatively high precision. Studies employing these methods have provided new insights into the causes and consequences of the hostile tumor microenvironment. Furthermore, it is quite exciting that there are emerging techniques that generate tumor image contrast via ill-defined mechanisms. Elucidation of these mechanisms will yield further insights into the tumor microenvironment. This review attempts to identify techniques and their application to tumor biology, with an emphasis on nuclear magnetic resonance (NMR) approaches. Examples are also discussed using electron MR, optical, and radionuclear imaging techniques.
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Affiliation(s)
- Robert J Gillies
- Department of Biochemistry, Arizona Cancer Center, University of Arizona HSC, Tucson, Arizona 85724-5024, USA.
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329
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Turner KJ, Crew JP, Wykoff CC, Watson PH, Poulsom R, Pastorek J, Ratcliffe PJ, Cranston D, Harris AL. The hypoxia-inducible genes VEGF and CA9 are differentially regulated in superficial vs invasive bladder cancer. Br J Cancer 2002; 86:1276-82. [PMID: 11953885 PMCID: PMC2375338 DOI: 10.1038/sj.bjc.6600215] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2001] [Revised: 01/16/2002] [Accepted: 01/24/2002] [Indexed: 11/09/2022] Open
Abstract
Regulation by hypoxia may underlie the expression of vascular endothelial growth factor in bladder cancer. We have compared the distribution of vascular endothelial growth factor mRNA with a hypoxia marker, carbonic anhydrase 9 (CA IX). vascular endothelial growth factor mRNA was analysed by in situ hybridisation and CA IX by immunochemistry in 22 cases of bladder cancer. The relationship of microvessels to the distribution of CA IX was determined. In a separate series of 49 superficial tumours, CA IX immunostaining was compared with clinico-pathological outcome. In superficial and invasive disease there was overlap in the expression of vascular endothelial growth factor and CA IX, CA IX being more widespread. Both were expressed predominantly on the luminal surface, and surrounding areas of necrosis (invasive tumours). Expression of both factors was greater in superficial disease. Expression was absent within approximately 80 microm of microvessels. Unlike vascular endothelial growth factor, CA IX did not predict outcome in superficial disease. Differential responses to reoxygenation provide one explanation: vascular endothelial growth factor mRNA declined rapidly, while CA IX expression was sustained for >72 h. Expression of vascular endothelial growth factor mRNA in bladder tumours is consistent with hypoxic regulation and suggests differential regulation in superficial vs invasive disease. The expression of CA IX on the luminal surface justifies investigation of its utility as a therapeutic target/prognostic indicator.
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Affiliation(s)
- K J Turner
- ICRF Molecular Oncology Laboratory and Angiogenesis Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU, UK
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330
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Bhujwalla ZM, Artemov D, Ballesteros P, Cerdan S, Gillies RJ, Solaiyappan M. Combined vascular and extracellular pH imaging of solid tumors. NMR IN BIOMEDICINE 2002; 15:114-119. [PMID: 11870907 DOI: 10.1002/nbm.743] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The unique physiological environment of solid tumors, frequently characterized by areas of poor flow, hypoxia, high lactate and low extracellular pH (pHe), influences vascularization, invasion and metastasis. Thus, vascularization and the physiological and metabolic environment play permissive (and conversely preventive) roles in invasion and metastasis. By using a multi-parametric approach of combined vascular and spectroscopic imaging, we can begin to evaluate which combinations of vascular, metabolic and physiological regions in a solid tumor represent the highest 'metastatic threat'. Here, we present measurements of pHe, vascular volume and permeability from co-localized regions within a solid tumor. These studies were performed for a group of metastatic (MDA-MB-231) and non-metastatic (MCF-7) human breast cancer xenografts. In this study, we have demonstrated the feasibility of such an approach, and presented methods of analyses to detect differences in patterns of combined parameters obtained from spatially co-registered regions in a solid tumor.
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Affiliation(s)
- Z M Bhujwalla
- MR Oncology Section, Division of MR Research, Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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331
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Brizel DM, Schroeder T, Scher RL, Walenta S, Clough RW, Dewhirst MW, Mueller-Klieser W. Elevated tumor lactate concentrations predict for an increased risk of metastases in head-and-neck cancer. Int J Radiat Oncol Biol Phys 2001; 51:349-53. [PMID: 11567808 DOI: 10.1016/s0360-3016(01)01630-3] [Citation(s) in RCA: 420] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE Hypoxia shifts the balance of cellular energy production toward glycolysis with lactate generation as a by-product. Quantitative bioluminescence imaging allows for the quantitation of lactate concentrations in individual tumors. We assessed the relationship between pretreatment tumor lactate concentrations and subsequent development of metastatic disease in patients with newly diagnosed head-and-neck cancer. METHODS AND MATERIALS At the time of biopsy of the primary site, a separate specimen was taken and flash-frozen for subsequent quantitation of lactate concentration using a luciferase bioluminescence technique. The two-dimensional spatial distribution of the bioluminescence intensity within the tissue section was registered directly using a microscope and an imaging photon counting system. Photon intensity was converted to distributions of volume-related tissue concentrations (micromol per gram wet weight). Treatment consisted of either surgery and postoperative radiotherapy or primary radiotherapy, based on presenting disease stage and institutional treatment policies. The subsequent development of metastatic disease constituted the primary clinical endpoint. RESULTS Biopsies obtained from 40 patients were evaluable in 34. The larynx was the most frequent primary site (n = 25). Other sites included oropharynx (n = 5), hypopharynx (n = 3), and oral cavity (n = 1). Most patients (74%) presented with an advanced stage T3 or T4 primary tumor. Nodal involvement was present in 19 (54%) patients. The median tumor lactate concentration was 7.1 micromol/g. Tumors were classified as having either low or high lactate concentrations according to whether these values were below or above the median. The median follow-up time for surviving patients is 27 months. Two-year actuarial survival was 90% for patients with low-lactate-concentration tumor vs. 35% for patients with high-lactate-concentration primaries (<0.0001). Two-year metastasis-free survival was adversely influenced by high tumor lactate concentrations (90% vs. 25%, p < 0.0001). The median lactate concentration for tumors that subsequently metastasized was 12.9 micromol/g vs. 4.8 micromol/g for patients who remained continuously free of disease (p < 0.005). Lactate concentration was not correlated with presenting T stage or N stage. DISCUSSION Elevated tumor lactate concentrations are associated with the subsequent development of nodal or distant metastases in head-and-neck cancer patients. This more aggressive malignant phenotype is probably associated with hypoxia-mediated radioresistance and the upregulation of metastasis-associated genes.
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Affiliation(s)
- D M Brizel
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
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332
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Crowther M, Brown NJ, Bishop ET, Lewis CE. Microenvironmental influence on macrophage regulation of angiogenesis in wounds and malignant tumors. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.4.478] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- M. Crowther
- Tumor Targeting Group, Section of Oncology & Pathology, Division of Genomic Medicine, and Sheffield S10 2RX
| | - N. J. Brown
- Microcirculation Unit, Surgical & Anaesthetic Sciences, Division of Clinical Sciences, University of Sheffield Medical School, Sheffield S10 2RX, and
| | - E. T. Bishop
- Medisys PLC, Cell Pathology Unit, University of Aberdeen, Aberdeen AB24 5UA, United Kingdom
| | - C. E. Lewis
- Tumor Targeting Group, Section of Oncology & Pathology, Division of Genomic Medicine, and Sheffield S10 2RX
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333
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Whittington DA, Waheed A, Ulmasov B, Shah GN, Grubb JH, Sly WS, Christianson DW. Crystal structure of the dimeric extracellular domain of human carbonic anhydrase XII, a bitopic membrane protein overexpressed in certain cancer tumor cells. Proc Natl Acad Sci U S A 2001; 98:9545-50. [PMID: 11493685 PMCID: PMC55489 DOI: 10.1073/pnas.161301298] [Citation(s) in RCA: 234] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2001] [Indexed: 01/06/2023] Open
Abstract
Overexpression of the zinc enzyme carbonic anhydrase (CA; EC ) XII is observed in certain human cancers. This bitopic membrane protein contains an N-terminal extracellular catalytic domain, a membrane-spanning alpha-helix, and a small intracellular C-terminal domain. We have determined the three-dimensional structure of the extracellular catalytic domain of human CA XII by x-ray crystallographic methods at 1.55-A resolution. The structure reveals a prototypical CA fold; however, two CA XII domains associate to form an isologous dimer, an observation that is confirmed by studies of the enzyme in solution. The identification of signature GXXXG and GXXXS motifs in the transmembrane sequence that facilitate helix-helix association is additionally consistent with dimeric architecture. The dimer interface is situated so that the active site clefts of each monomer are clearly exposed on one face of the dimer, and the C termini are located together on the opposite face of the dimer to facilitate membrane interaction. The amino acid composition of the active-site cleft closely resembles that of the other CA isozymes in the immediate vicinity of the catalytic zinc ion, but differs in the region of the nearby alpha-helical "130's segment." The structure of the CA XII-acetazolamide complex is also reported at 1.50-A resolution, and prospects for the design of CA XII-specific inhibitors of possible chemotherapeutic value are discussed.
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Affiliation(s)
- D A Whittington
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA
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334
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Affiliation(s)
- W S Sly
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, 1402 South Grand Blvd., St. Louis, MO 63104, USA
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335
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Chegwidden WR, Dodgson SJ, Spencer IM. The roles of carbonic anhydrase in metabolism, cell growth and cancer in animals. EXS 2001:343-63. [PMID: 11268523 DOI: 10.1007/978-3-0348-8446-4_16] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- W R Chegwidden
- Lake Erie College of Osteopathic Medicine, 1858 West Grandview Boulevard, Erie, PA 16509, USA
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336
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Folberg R, Fleck M, Mehaffey MG, Meyer M, Bentler SE, Woolson RF, Pe'er J. Mapping the Location of Prognostically Significant Microcirculatory Patterns in Ciliary Body and Choroidal Melanomas. Pathol Oncol Res 2001; 2:229-236. [PMID: 11173608 DOI: 10.1007/bf02904815] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The microcirculation of choroidal and ciliary body melanomas is remodeled into architecturally distinctive patterns. The presence of two histologic microvascular patterns, networks and parallel vessels with cross-linking, is strongly associated with metastasis. This study was designed to test the hypothesis that networks and parallel vessels with cross-linking patterns are not distributed evenly throughout the tumor. From a set of 234 eyes removed for ciliary body or choroidal melanoma, 152 tumors contained at least one focus of either vascular networks or parallel vessels with cross-linking. Histological cross-sections were digitized and foci of tumor containing these patterns were pseudocolorized so that their location within the periphery or central tumor zone could be mapped. Ciliary body and choroidal melanomas vary widely in size and shape and it is not appropriate to describe the periphery of a tumor as a fixed value because in a small tumor, the periphery thus defined would occupy a larger percent area than in a larger tumor. In this study, the peripheral and central zones of each tumor were described by a function that was constant from tumor to tumor, allowing the width of the peripheral and central zones to vary proportionally with tumor size. Observed counts of vascular patterns per zone were compared statistically with expected counts based upon the percent area occupied by the peripheral and central zones. Discrete foci of networks and parallel with cross-linking vessels are over-represented in the tumor periphery (p < 0.0001).
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Affiliation(s)
- Robert Folberg
- University of Iowa, Departments of Ophthalmology, Iowa, USA
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337
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Parkkila S, Parkkila AK, Saarnio J, Kivelä J, Karttunen TJ, Kaunisto K, Waheed A, Sly WS, Türeci O, Virtanen I, Rajaniemi H. Expression of the membrane-associated carbonic anhydrase isozyme XII in the human kidney and renal tumors. J Histochem Cytochem 2000; 48:1601-8. [PMID: 11101628 DOI: 10.1177/002215540004801203] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Carbonic anhydrase isozyme XII (CA XII) is a novel membrane-associated protein with a potential role in von Hippel-Lindau carcinogenesis. Although Northern blotting has revealed positive signal for CA XII in normal human kidney, this is the first study to demonstrate its cellular and subcellular localization along the human nephron and collecting duct. Immunohistochemistry with a polyclonal antibody (PAb) raised against truncated CA XII revealed distinct staining in the basolateral plasma membrane of the epithelial cells in the thick ascending limb of Henle and distal convoluted tubules, and in the principal cells of the collecting ducts. A weak basolateral signal was also detected in the epithelium of the proximal convoluted tubules. In addition to the normal kidney specimens, this immunohistochemical study included 31 renal tumors. CA XII showed moderate or strong plasma membrane-associated expression in most oncocytomas and clear-cell carcinomas. The segmental, cellular, and subcellular distribution of CA XII along the human nephron and collecting duct suggests that it may be one of the key enzymes involved in normal renal physiology, particularly in the regulation of water homeostasis. High expression of CA XII in some renal carcinomas may contribute to its role in von Hippel-Lindau carcinogenesis.
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Affiliation(s)
- S Parkkila
- Departments of Anatomy and Cell Biology, University of Oulu, Oulu, Finland.
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338
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Abstract
PURPOSE To present and evaluate clinical data suggesting that cancer metastasis may be induced by the microenvironment of the primary tumour and to discuss possible mechanisms of microenvironment-induced metastasis, based on a critical review of relevant data from studies of experimental tumours and cells in culture. CONCLUSIONS Low oxygen tension in the primary tumour is associated with metastasis in soft tissue sarcoma, cervix carcinoma and carcinoma of the head and neck. Multiple mechanisms may be involved in hypoxia-induced metastasis. Thus, hypoxia followed by reoxygenation may induce point mutations and DNA strand breakage leading to deletions, amplifications and genomic instability. Hypoxia may also provide a physiological pressure in tumours selecting for metastatic cell phenotypes. Moreover, hypoxia may induce a temporary increase in the expression of gene products involved in the metastatic cascade, either through gene amplifications or through normal physiological processes by activating oxygen sensors, hypoxia signal transduction pathways and DNA transcription factors. Low glucose concentration, high lactate concentration and low extracellular pH may induce metastasis by similar mechanisms as hypoxia. Tumour reoxygenation during radiation therapy may promote microenvironment-induced metastasis by rescuing hypoxic or nutritionally deprived metastatic cells from dying. Ionizing radiation can elicit a stress response in tumour cells similar to that elicited by hypoxia. Radiation therapy may therefore adversely affect the rate of metastasis in patients who do not achieve control of the primary tumour by enhancing the expression of gene products of importance in metastasis.
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Affiliation(s)
- E K Rofstad
- Department of Biophysics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo.
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339
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Johnson LL, Pavlovsky AG, Johnson AR, Janowicz JA, Man CF, Ortwine DF, Purchase CF, White AD, Hupe DJ. A rationalization of the acidic pH dependence for stromelysin-1 (Matrix metalloproteinase-3) catalysis and inhibition. J Biol Chem 2000; 275:11026-33. [PMID: 10753905 DOI: 10.1074/jbc.275.15.11026] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The pH dependence of matrix metalloproteinase (MMP) catalysis is described by a broad bell-shaped curve, indicating the involvement of two unspecified ionizable groups in proteolysis. Stromelysin-1 has a third pK(a) near 6, resulting in a uniquely sharp acidic catalytic optimum, which has recently been attributed to His(224). This suggests the presence of a critical, but unidentified, S1' substructure. Integrating biochemical characterizations of inhibitor-enzyme interactions with active site topography from corresponding crystal structures, we isolated contributions to the pH dependence of catalysis and inhibition of active site residues Glu(202) and His(224). The acidic pK(a) 5.6 is attributed to the Glu(202).zinc.H(2)O complex, consistent with a role for the invariant active site Glu as a general base in MMP catalysis. The His(224)-dependent substructure is identified as a tripeptide (Pro(221)-Leu(222)-Tyr(223)) that forms the substrate cleft lower wall. Substrate binding induces a beta-conformation in this sequence, which extends and anchors the larger beta-sheet of the enzyme. substrate complex and appears to be essential for productive substrate binding. Because the PXY tripeptide is strictly conserved among MMPs, this "beta-anchor" may represent a common motif required for macromolecular substrate hydrolysis. The striking acidic profile of stromelysin-1 defined by the combined ionization of Glu(202) and His(224) allows the design of highly selective inhibitors.
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Affiliation(s)
- L L Johnson
- Department of Cancer Research, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Co., Ann Arbor, Michigan 48105, USA.
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340
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McLean LA, Roscoe J, Jorgensen NK, Gorin FA, Cala PM. Malignant gliomas display altered pH regulation by NHE1 compared with nontransformed astrocytes. Am J Physiol Cell Physiol 2000; 278:C676-88. [PMID: 10751317 DOI: 10.1152/ajpcell.2000.278.4.c676] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Malignant gliomas exhibit alkaline intracellular pH (pH(i)) and acidic extracellular pH (pH(e)) compared with nontransformed astrocytes, despite increased metabolic H(+) production. The acidic pH(e) limits the availability of HCO(-)(3), thereby reducing both passive and dynamic HCO(-)(3)-dependent buffering. This implies that gliomas are dependent upon dynamic HCO(-)(3)-independent H(+) buffering pathways such as the type 1 Na(+)/H(+) exchanger (NHE1). In this study, four rapidly proliferating gliomas exhibited significantly more alkaline steady-state pH(i) (pH(i) = 7.31-7.48) than normal astrocytes (pH(i) = 6.98), and increased rates of recovery from acidification, under nominally CO(2)/HCO(-)(3)-free conditions. Inhibition of NHE1 in the absence of CO(2)/HCO(-)(3) resulted in pronounced acidification of gliomas, whereas normal astrocytes were unaffected. When suspended in CO(2)/HCO(-)(3) medium astrocyte pH(i) increased, yet glioma pH(i) unexpectedly acidified, suggesting the presence of an HCO(-)(3)-dependent acid loading pathway. Nucleotide sequencing of NHE1 cDNA from the gliomas demonstrated that genetic alterations were not responsible for this altered NHE1 function. The data suggest that NHE1 activity is significantly elevated in gliomas and may provide a useful target for the development of tumor-selective therapies.
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Affiliation(s)
- L A McLean
- Department of Human Physiology, School of Medicine, University of California, Davis, California 95616, USA
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341
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Parkkila S, Rajaniemi H, Parkkila AK, Kivela J, Waheed A, Pastorekova S, Pastorek J, Sly WS. Carbonic anhydrase inhibitor suppresses invasion of renal cancer cells in vitro. Proc Natl Acad Sci U S A 2000; 97:2220-4. [PMID: 10688890 PMCID: PMC15781 DOI: 10.1073/pnas.040554897] [Citation(s) in RCA: 215] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Acidification of the extracellular milieu of malignant tumors is reported to increase the invasive behavior of cancer cells. In normal tissues, production of acid is catalyzed by carbonic anhydrases (CAs), some of which are known to be overexpressed in certain cancers. To investigate the functional role of CA activity in such cancer cells, we analyzed the effect of acetazolamide, a potent CA inhibitor, on the invasive capacity of four renal carcinoma cell lines (Caki-1, Caki-2, ACHN, and A-498). We found that 10 microM acetazolamide inhibited the relative invasion rate of these cell lines between 18-74%. The Caki-2 and ACHN cell lines displayed the highest responsiveness, and their responses clearly depended on the acetazolamide concentration in the culture medium. Immunocytochemical and Western blotting results identified the presence of CA isoenzyme II in the cytoplasm of all four cell lines and CA XII on the plasma membrane in three of four cell lines. Because acetazolamide alone reduced invasiveness of these cancer cells in vitro, we conclude that the CAs overexpressed in these renal cancer cells contribute to invasiveness, at least in vitro, and suggest that CA inhibitors may also reduce invasiveness in other tumors that overexpress one or more CAs.
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Affiliation(s)
- S Parkkila
- Department of Anatomy, 90014 University of Oulu, Finland
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342
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Reshkin SJ, Bellizzi A, Albarani V, Guerra L, Tommasino M, Paradiso A, Casavola V. Phosphoinositide 3-kinase is involved in the tumor-specific activation of human breast cancer cell Na(+)/H(+) exchange, motility, and invasion induced by serum deprivation. J Biol Chem 2000; 275:5361-9. [PMID: 10681510 DOI: 10.1074/jbc.275.8.5361] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Whereas the tumor acidic extracellular pH plays a crucial role in the invasive process, the mechanism(s) behind this acidification, especially in low nutrient conditions, are unclear. The regulation of the Na(+)/H(+) exchanger (NHE) and invasion by serum deprivation were studied in a series of breast epithelial cell lines representing progression from non-tumor to highly metastatic cells. Whereas serum deprivation reduced lactate production in all three cells lines, it inhibited NHE activity in the non-tumor cells and stimulated it in the tumor cells with a larger stimulation in the metastatic cells. The stimulation of NHE in the tumor cell lines was the result of an increased affinity of the internal H(+) regulatory site of the NHE without changes in sodium kinetics or expression. Serum deprivation conferred increased cell motility and invasive ability that were abrogated by specific inhibition of the NHE. Inhibition of phosphoinositide 3-kinase by overexpression of a dominant-negative mutant or wortmannin incubation inhibited NHE activity and invasion in serum replete conditions while potentiating the serum deprivation-dependent activation of the NHE and invasion. These results indicate that the up-regulation of the NHE by a phosphoinositide 3-kinase-dependent mechanism plays an essential role in increased tumor cell invasion induced by serum deprivation.
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Affiliation(s)
- S J Reshkin
- Department of General Physiology, University of Bari, 70126 Bari, Italy.
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343
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Expression of a novel transmembrane carbonic anhydrase isozyme XII in normal human gut and colorectal tumors. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 156:577-84. [PMID: 10666387 PMCID: PMC1850052 DOI: 10.1016/s0002-9440(10)64762-1] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Carbonic anhydrase isozyme XII is a recently discovered member of the alpha-carbonic anhydrase gene family with a suggested role in von Hippel-Lindau gene-mediated carcinogenesis. Increased expression of its mRNA has been observed in renal and lung carcinomas. This paper presents the localization of CA XII in the normal human gut and in colorectal tumors. Immunohistochemistry performed using a polyclonal antibody raised against truncated CA XII revealed prominent polarized staining for CA XII in the basolateral plasma membrane of the enterocytes of the normal large intestine, the reaction being most intense in the surface epithelial cuff region. Most colorectal tumors displayed abnormal expression of CA XII; the most dramatic change was observed in the deep parts of the adenomatous mucosa, where the positive immunoreaction clearly increased along with the grade of dysplasia. Adenomas with severe dysplasia and carcinomas showed an equal, diffuse staining pattern. The results indicate region-specific regulation of CA XII expression along the cranial-caudal axis of the human gut, whereas its diffuse expression in the most malignant tumors seems to correlate with their biological behavior.
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344
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Kato Y, Frankenne F, Noël A, Sakai N, Nagashima Y, Koshika S, Miyazaki K, Foidart JM. High production of SPARC/osteonectin/BM-40 in mouse metastatic B16 melanoma cell lines. Pathol Oncol Res 2000; 6:24-6. [PMID: 10749584 DOI: 10.1007/bf03032654] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Production of SPARC/osteonectin/BM-40 was determined in mouse B16 melanoma clones BL6 and F10 (high metastatic) and F1 (low metastatic). SPARC was produced greater amount in BL6 and F10 than in F1 cells, showing a good agreement with their metastatic potentials. Moreover, SPARC production was not influenced by culture pH, even in the acidic conditions (= pH 5.9). Although tumor tissues show often low pH due to excessive amount of acidic metabolites such as lactate, most studies have been done in neutral pH. High SPARC production in the acidic medium, therefore, is thought to be an important potential for tumor invasive behaviour.
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Affiliation(s)
- Y Kato
- Kanagawa Dental College, Department of Biochemistry 82 Inaoka-cho, Yokosuka, 238-8580, Japan.
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345
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Gillies RJ, Bhujwalla ZM, Evelhoch J, Garwood M, Neeman M, Robinson SP, Sotak CH, Van Der Sanden B. Applications of magnetic resonance in model systems: tumor biology and physiology. Neoplasia 2000; 2:139-51. [PMID: 10933073 PMCID: PMC1531870 DOI: 10.1038/sj.neo.7900076] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/1999] [Accepted: 10/13/1999] [Indexed: 01/14/2023]
Abstract
A solid tumor presents a unique challenge as a system in which the dynamics of the relationship between vascularization, the physiological environment and metabolism are continually changing with growth and following treatment. Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) studies have demonstrated quantifiable linkages between the physiological environment, angiogenesis, vascularization and metabolism of tumors. The dynamics between these parameters continually change with tumor aggressiveness, tumor growth and during therapy and each of these can be monitored longitudinally, quantitatively and non-invasively with MRI and MRS. An important aspect of MRI and MRS studies is that techniques and findings are easily translated between systems. Hence, pre-clinical studies using cultured cells or experimental animals have a high connectivity to potential clinical utility. In the following review, leaders in the field of MR studies of basic tumor physiology using pre-clinical models have contributed individual sections according to their expertise and outlook. The following review is a cogent and timely overview of the current capabilities and state-of-the-art of MRI and MRS as applied to experimental cancers. A companion review deals with the application of MR methods to anticancer therapy.
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Affiliation(s)
- R J Gillies
- Department of Biochemistry, Arizona Cancer Center, University of Arizona, Tucson 85724-5024, USA.
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346
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Yang JM, Yang GY, Medina DJ, Vassil AD, Liao J, Hait WN. Treatment of multidrug resistant (MDR1) murine leukemia with P-glycoprotein substrates accelerates the course of the disease. Biochem Biophys Res Commun 1999; 266:167-73. [PMID: 10581184 DOI: 10.1006/bbrc.1999.1757] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The prognosis of patients with tumors expressing P-glycoprotein (P-gp), the MDR1 gene product, is generally poor. It is assumed that this is due to decreased tumor responsiveness that results from decreased drug accumulation. We observed that treatment of animals bearing MDR1-transfected leukemic cells with P-gp substrates (i.e., drugs that are transported by P-gp) significantly worsened host survival compared to treatment with vehicle or non-P-gp substrates. This effect was seen with cancer chemotherapeutic agents (paclitaxel and vincristine) and with the MDR modulator, trans-flupenthixol. To determine the mechanism(s) underlying this observation, we studied alterations in pharmacokinetics, pharmacodynamics, and metastasis. We found that the drug-induced acceleration of disease was associated with increased metastases. P-gp(+) cells treated with P-gp substrates demonstrated several pro-metastatic features, including membrane ruffling and invasion through a hepatocyte monolayer. These results suggest that the treatment of MDR tumors with P-gp substrates may produce changes in malignant behavior that could adversely affect therapeutic outcomes.
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Affiliation(s)
- J M Yang
- The Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey/Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA.
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347
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Ojugo AS, McSheehy PM, McIntyre DJ, McCoy C, Stubbs M, Leach MO, Judson IR, Griffiths JR. Measurement of the extracellular pH of solid tumours in mice by magnetic resonance spectroscopy: a comparison of exogenous (19)F and (31)P probes. NMR IN BIOMEDICINE 1999; 12:495-504. [PMID: 10668042 DOI: 10.1002/(sici)1099-1492(199912)12:8<495::aid-nbm594>3.0.co;2-k] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Precise measurement of pH(e) in vivo may be of clinical value for both diagnosis and selection of therapy. pH(e) measurements made by the (31)P probe 3-aminopropylphosphonate (3-APP) were compared with those made by the (19)F probe, 3-[N-(4-fluor-2-trifluoromethylphenyl)-sulphamoyl]-propionic acid (ZK-150471) in three solid tumour types, human HT29 xenografts, murine RIF-1 fibrosarcomas and Lettre tumours grown subcutaneously in mice. No significant differences were observed when probe measurements of pH(e) were compared at 20-60 min post-administration, although very low pH(e) values (ca. 6.0) were recorded in two out of eight Lettre tumours by ZK-150471. The more rapid pH(e) measurements possible using ZK-150471 showed that during the first 20 min post-administration significant increases occurred in pH(e) which were greatest in the more necrotic tumours. Since isolated cell experiments showed that ZK-150471 was non-toxic and did not enter the cells, this early increase in pH(e) may reflect gradual penetration by ZK-150471 of the reportedly alkaline necrotic space in the tumours. The wide chemical shift range, improved signal-to-noise and absence of signal overlap allowed a more rapid and precise measurement of pH(e) by ZK-150471 compared to 3-APP. These characteristics suggest that ZK-150471 is currently the preferred pH(e) probe for non-invasive MRS.
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Affiliation(s)
- A S Ojugo
- CRC Biomedical Magnetic Resonance Research Group, Department of Biochemistry, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK
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348
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Gillies RJ, Schornack PA, Secomb TW, Raghunand N. Causes and effects of heterogeneous perfusion in tumors. Neoplasia 1999; 1:197-207. [PMID: 10935474 PMCID: PMC1508079 DOI: 10.1038/sj.neo.7900037] [Citation(s) in RCA: 193] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/1999] [Accepted: 05/27/1999] [Indexed: 12/11/2022]
Abstract
A characteristic of solid tumors is their heterogeneous distribution of blood flow, with significant hypoxia and acidity in low-flow regions. We review effects of heterogeneous tumor perfusion are reviewed and propose a conceptual model for its cause. Hypoxic-acidic regions are resistant to chemo- and radiotherapy and may stimulate progression to a more metastatic phenotype. In normal tissues, hypoxia and acidity induce angiogenesis, which is expected to improve perfusion. However, aggressive tumors can have high local microvessel density simultaneously with significant regions of hypoxia and acidosis. A possible explanation for this apparent contradiction is that the mechanisms regulating growth and adaptation of vascular networks are impaired. According to a recent theory for structural adaptation of vascular networks, four interrelated adaptive responses can work as a self-regulating system to produce a mature and efficient blood distribution system in normal tissues. It is proposed that heterogeneous perfusion in tumors may result from perturbation of this system. Angiogenesis may increase perfusion heterogeneity in tumors by increasing the disparity between parallel low- and high-resistance flow pathways. This conceptual model provides a basis for future rational therapies. For example, it indicates that selective destruction of tumor vasculature may increase perfusion efficiency and improve therapeutic efficacy.
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Affiliation(s)
- R J Gillies
- Arizona Cancer Center, University of Arizona, Tucson 85724-5024, USA.
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349
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Diwu Z, Chen CS, Zhang C, Klaubert DH, Haugland RP. A novel acidotropic pH indicator and its potential application in labeling acidic organelles of live cells. CHEMISTRY & BIOLOGY 1999; 6:411-8. [PMID: 10381401 DOI: 10.1016/s1074-5521(99)80059-3] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Ratio imaging has received intensive attention in the past few decades. The growing potential of ratio imaging is significantly limited, however, by the lack of appropriate fluorescent probes, for acidic organelles in particular. The classic fluorescent dyes (such as fluoresceins, rhodamines and coumarins) are not suitable for studying acidic organelles (such as lysosomes) because their fluorescence is significantly decreased under neutral or acidic conditions. This has motivated us to develop probes that can be used in ratio imaging that are strongly fluorescent even in acidic media. RESULTS The compound 2-(4-pyridyl)-5-((4-(2-dimethylaminoethyl-aminocarbamoyl) methoxy)phenyl)oxazole (PDMPO) was prepared and characterized as a new acidotropic dual-excitation and dual-emission pH indicator. It emits intense yellow fluorescence at lower pH and gives intense blue fluorescence at higher pH. This unique pH-dependent fluorescence property was readily explored to selectively stain lysosomes and to determine the pH of the organelle in an emission-ratio-imaging mode. PDMPO is selectively localized to lysosomes and exhibits a pH-dependent dual excitation and emission. CONCLUSIONS PDMPO selectively labels acidic organelles (such as lysosomes) of live cells and the two distinct emission peaks can be used to monitor the pH fluctuations of live cells in ratio measurements. Additionally, the very large Stokes shift and excellent photostability of PDMPO make the compound an ideal fluorescent acidotropic probe. The unique fluorescence properties of PDMPO might give researchers a new tool with which to study acidic organelles of live cells.
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Affiliation(s)
- Z Diwu
- Molecular Probes Incorporated, 4849 Pitchford Avenue, Eugene, Oregon 97402, USA.
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350
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Ohh M, Kaelin WG. The von Hippel-Lindau tumour suppressor protein: new perspectives. MOLECULAR MEDICINE TODAY 1999; 5:257-63. [PMID: 10366821 DOI: 10.1016/s1357-4310(99)01481-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
von Hippel-Lindau (VHL) disease is a hereditary cancer syndrome caused by germline mutations of the VHL tumour suppressor gene. The VHL gene product, pVHL, forms multiprotein complexes that contain elongin B, elongin C and Cul-2, and negatively regulates hypoxia-inducible mRNAs. pVHL is suspected to play a role in ubiquitination given the similarity of elongin C and Cul-2 with Skp1 and Cdc53, respectively. pVHL can also interact with fibronectin and is required for the assembly of a fibronectin matrix. Finally, pVHL, at least indirectly, plays a role in the ability of cells to exit the cell cycle. Thus, pVHL is a tumour suppressor protein that regulates angiogenesis, extracellular matrix formation and the cell cycle.
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Affiliation(s)
- M Ohh
- Howard Hughes Medical Institute, Division of Adult Oncology, Dana-Farber Cancer Institute and Dept of Medicine, Harvard Medical School, Boston, MA 02115, USA
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