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Riemann A, Rauschner M, Reime S, Thews O. The Role of microRNAs in Gene Expression and Signaling Response of Tumor Cells to an Acidic Environment. Int J Mol Sci 2023; 24:16919. [PMID: 38069241 PMCID: PMC10707721 DOI: 10.3390/ijms242316919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/23/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
Many tumors are characterized by marked extracellular acidosis due to increased glycolytic metabolism, which affects gene expression and thereby tumor biological behavior. At the same time, acidosis leads to altered expression of several microRNAs (Mir7, Mir183, Mir203, Mir215). The aim of this study was to analyze whether the acidosis-induced changes in cytokines and tumor-related genes are mediated via pH-sensitive microRNAs. Therefore, the expression of Il6, Nos2, Ccl2, Spp1, Tnf, Acat2, Aox1, Crem, Gls2, Per3, Pink1, Txnip, and Ypel3 was examined in acidosis upon simultaneous transfection with microRNA mimics or antagomirs in two tumor lines in vitro and in vivo. In addition, it was investigated whether microRNA expression in acidosis is affected via known pH-sensitive signaling pathways (MAPK, PKC, PI3K), via ROS, or via altered intracellular Ca2+ concentration. pH-dependent microRNAs were shown to play only a minor role in modulating gene expression. Individual genes (e.g., Ccl2, Txnip, Ypel3) appear to be affected by Mir183, Mir203, or Mir215 in acidosis, but these effects are cell line-specific. When examining whether acid-dependent signaling affects microRNA expression, it was found that Mir203 was modulated by MAPK and ROS, Mir7 was affected by PKC, and Mir215 was dependent on the intracellular Ca2+ concentration. Mir183 could be increased by ROS scavenging. These correlations could possibly result in new therapeutic approaches for acidotic tumors.
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Affiliation(s)
| | | | | | - Oliver Thews
- Julius Bernstein Institute of Physiology, University of Halle-Wittenberg, 06108 Halle, Germany
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Leng Q, Imtiyaz Z, Woodle MC, Mixson AJ. Delivery of Chemotherapy Agents and Nucleic Acids with pH-Dependent Nanoparticles. Pharmaceutics 2023; 15:1482. [PMID: 37242725 PMCID: PMC10222096 DOI: 10.3390/pharmaceutics15051482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/18/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
With less than one percent of systemically injected nanoparticles accumulating in tumors, several novel approaches have been spurred to direct and release the therapy in or near tumors. One such approach depends on the acidic pH of the extracellular matrix and endosomes of the tumor. With an average pH of 6.8, the extracellular tumor matrix provides a gradient for pH-responsive particles to accumulate, enabling greater specificity. Upon uptake by tumor cells, nanoparticles are further exposed to lower pHs, reaching a pH of 5 in late endosomes. Based on these two acidic environments in the tumor, various pH-dependent targeting strategies have been employed to release chemotherapy or the combination of chemotherapy and nucleic acids from macromolecules such as the keratin protein or polymeric nanoparticles. We will review these release strategies, including pH-sensitive linkages between the carrier and hydrophobic chemotherapy agent, the protonation and disruption of polymeric nanoparticles, an amalgam of these first two approaches, and the release of polymers shielding drug-loaded nanoparticles. While several pH-sensitive strategies have demonstrated marked antitumor efficacy in preclinical trials, many studies are early in their development with several obstacles that may limit their clinical use.
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Affiliation(s)
- Qixin Leng
- Department of Pathology, University Maryland School of Medicine, University of Maryland, 10 S. Pine St., Baltimore, MD 21201, USA (Z.I.)
| | - Zuha Imtiyaz
- Department of Pathology, University Maryland School of Medicine, University of Maryland, 10 S. Pine St., Baltimore, MD 21201, USA (Z.I.)
| | | | - A. James Mixson
- Department of Pathology, University Maryland School of Medicine, University of Maryland, 10 S. Pine St., Baltimore, MD 21201, USA (Z.I.)
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Imtiyaz Z, He J, Leng Q, Agrawal AK, Mixson AJ. pH-Sensitive Targeting of Tumors with Chemotherapy-Laden Nanoparticles: Progress and Challenges. Pharmaceutics 2022; 14:pharmaceutics14112427. [PMID: 36365245 PMCID: PMC9692785 DOI: 10.3390/pharmaceutics14112427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/03/2022] [Accepted: 11/05/2022] [Indexed: 11/12/2022] Open
Abstract
Accumulating chemotherapeutic drugs such as doxorubicin within a tumor while limiting the drug dose to normal tissues is a central goal of drug delivery with nanoparticles. Liposomal products such as Doxil® represent one of the marked successes of nanoparticle-based strategies. To replicate this success for cancer treatment, many approaches with nanoparticles are being explored in order to direct and release chemotherapeutic agents to achieve higher accumulation in tumors. A promising approach has been stimulus-based therapy, such as the release of chemotherapeutic agents from the nanoparticles in the acidic environments of the tumor matrix or the tumor endosomes. Upon reaching the acidic environments of the tumor, the particles, which are made up of pH-dependent polymers, become charged and release the entrapped chemotherapy agents. This review discusses recent advances in and prospects for pH-dependent histidine-based nanoparticles that deliver chemotherapeutic agents to tumors. The strategies used by investigators include an array of histidine-containing peptides and polymers which form micelles, mixed micelles, nanovesicles, polyplexes, and coat particles. To date, several promising histidine-based nanoparticles have been demonstrated to produce marked inhibition of tumor growth, but challenges remain for successful outcomes in clinical trials. The lessons learned from these histidine-containing particles will provide insight in the development of improved pH-dependent polymeric delivery systems for chemotherapy.
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Affiliation(s)
- Zuha Imtiyaz
- Department of Pathology, University Maryland School of Medicine, 10 S. Pine St., University of Maryland, Baltimore, MD 21201, USA
| | - Jiaxi He
- 20511 Seneca Meadows Pkwy, Suite 260, RNAimmune, Germantown, MD 20876, USA
| | - Qixin Leng
- Department of Pathology, University Maryland School of Medicine, 10 S. Pine St., University of Maryland, Baltimore, MD 21201, USA
| | - Atul K. Agrawal
- Department of Pathology, University Maryland School of Medicine, 10 S. Pine St., University of Maryland, Baltimore, MD 21201, USA
| | - A. James Mixson
- Department of Pathology, University Maryland School of Medicine, 10 S. Pine St., University of Maryland, Baltimore, MD 21201, USA
- Correspondence: ; Tel.: +1-410-706-3223; Fax: +1-410-706-8414
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Rauschner M, Reime S, Riemann A, Thews O. Acidosis-Induced Regulation of Egr1 and Ccn1 In Vitro and in Experimental Tumours In Vivo. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1395:243-248. [PMID: 36527644 DOI: 10.1007/978-3-031-14190-4_40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Extracellular acidosis is a characteristic of solid tumours, resulting from hypoxia-induced glycolytic metabolism as well as from the "Warburg effect" (aerobic glycolysis). The acidic environment has shown to affect functional tumour properties (proliferation, migration, invasion) and thus the aim of the study was to identify signalling mechanisms, mediating these pH-dependent effects. Therefore, the serum response factor (Srf) and the activation of the serum response element (SRE) by acidosis were analysed in AT-1 prostate carcinoma cells. Furthermore, the expression of downstream targets of this cascade, namely the early growth response 1 (Egr1), which seems to be involved in tumour proliferation, and the cellular communication network factor 1 (Ccn1), which both contain SRE in their promotor region were examined in two tumour cell lines. Extracellular acidification led to an upregulation of Srf and a functional activation of the SRE. Egr1 expression was increased by acidosis in AT-1 cells whereas hypoxia had a suppressive effect. In experimental tumours, in vivo Egr1 and Ccn1 were also found to be acidosis-dependent. Also, it turned out that pH regulated expression of Egr1 was followed by comparable changes of p21, which is an important regulator of the cell cycle.This study identifies the Srf-SRE signalling cascade and downstream Egr1 and Ccn1 to be acidosis-regulated in vitro and in vivo, potentially affecting tumour progression. Especially linked expression changes of Egr1 and p21 may mediate acidosis-induced effects on cell proliferation.
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Affiliation(s)
- M Rauschner
- Julius-Bernstein-Institute of Physiology, University of Halle, Halle, Germany
| | - S Reime
- Julius-Bernstein-Institute of Physiology, University of Halle, Halle, Germany
| | - A Riemann
- Julius-Bernstein-Institute of Physiology, University of Halle, Halle, Germany
| | - O Thews
- Julius-Bernstein-Institute of Physiology, University of Halle, Halle, Germany.
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Rauschner M, Hüsing T, Lange L, Jarosik K, Reime S, Riemann A, Thews O. Role of acidosis-sensitive microRNAs in gene expression and functional parameters of tumors in vitro and in vivo. Neoplasia 2021; 23:1275-1288. [PMID: 34781085 PMCID: PMC8605108 DOI: 10.1016/j.neo.2021.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/04/2021] [Indexed: 11/09/2022] Open
Abstract
Background: The acidic extracellular environment of tumors has been shown to affect the malignant progression of tumor cells by modulating proliferation, cell death or metastatic potential. The aim of the study was to analyze whether acidosis-dependent miRNAs play a role in the signaling cascade from low pH through changes in gene expression to functional properties of tumors in vitro and in vivo. Methods: In two experimental tumor lines the expression of 13 genes was tested under acidic conditions in combination with overexpression or downregulation of 4 pH-sensitive miRNAs (miR-7, 183, 203, 215). Additionally, the impact on proliferation, cell cycle distribution, apoptosis, necrosis, migration and cell adhesion were measured. Results: Most of the genes showed a pH-dependent expression, but only a few of them were additionally regulated by miRNAs in vitro (Brip1, Clspn, Rif1) or in vivo (Fstl, Tlr5, Txnip). Especially miR-215 overexpression was able to counteract the acidosis effect in some genes. The impact on proliferation was cell line-dependent and most pronounced with overexpression of miR-183 and miR-203, whereas apoptosis and necrosis were pH-dependent but not influenced by miRNAs. The tumor growth was markedly regulated by miR-183 and miR-7. In addition, acidosis had a strong effect on cell adhesion, which could be modulated by miR-7, miR-203 and miR-215. Conclusions: The results indicate that the acidosis effect on gene expression and functional properties of tumor cells could be mediated by pH-dependent miRNAs. Many effects were cell line dependent and therefore do not reflect universal intracellular signaling cascades. However, the role of miRNAs in the adaptation to an acidic environment may open new therapeutic strategies.
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Affiliation(s)
- Mandy Rauschner
- Julius Bernstein Institute of Physiology, University of Halle-Wittenberg, Magdeburger Str. 6, Halle (Saale) 06112, Germany
| | - Thea Hüsing
- Julius Bernstein Institute of Physiology, University of Halle-Wittenberg, Magdeburger Str. 6, Halle (Saale) 06112, Germany
| | - Luisa Lange
- Julius Bernstein Institute of Physiology, University of Halle-Wittenberg, Magdeburger Str. 6, Halle (Saale) 06112, Germany
| | - Kristin Jarosik
- Julius Bernstein Institute of Physiology, University of Halle-Wittenberg, Magdeburger Str. 6, Halle (Saale) 06112, Germany
| | - Sarah Reime
- Julius Bernstein Institute of Physiology, University of Halle-Wittenberg, Magdeburger Str. 6, Halle (Saale) 06112, Germany
| | - Anne Riemann
- Julius Bernstein Institute of Physiology, University of Halle-Wittenberg, Magdeburger Str. 6, Halle (Saale) 06112, Germany
| | - Oliver Thews
- Julius Bernstein Institute of Physiology, University of Halle-Wittenberg, Magdeburger Str. 6, Halle (Saale) 06112, Germany.
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Rauschner M, Lange L, Hüsing T, Reime S, Nolze A, Maschek M, Thews O, Riemann A. Impact of the acidic environment on gene expression and functional parameters of tumors in vitro and in vivo. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2021; 40:10. [PMID: 33407762 PMCID: PMC7786478 DOI: 10.1186/s13046-020-01815-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 12/13/2020] [Indexed: 02/06/2023]
Abstract
Background The low extracellular pH (pHe) of tumors resulting from glycolytic metabolism is a stress factor for the cells independent from concomitant hypoxia. The aim of the study was to analyze the impact of acidic pHe on gene expression on mRNA and protein level in two experimental tumor lines in vitro and in vivo and were compared to hypoxic conditions as well as combined acidosis+hypoxia. Methods Gene expression was analyzed in AT1 prostate and Walker-256 mammary carcinoma of the rat by Next Generation Sequencing (NGS), qPCR and Western blot. In addition, the impact of acidosis on tumor cell migration, adhesion, proliferation, cell death and mitochondrial activity was analyzed. Results NGS analyses revealed that 147 genes were uniformly regulated in both cell lines (in vitro) and 79 genes in both experimental tumors after 24 h at low pH. A subset of 25 genes was re-evaluated by qPCR and Western blot. Low pH consistently upregulated Aox1, Gls2, Gstp1, Ikbke, Per3, Pink1, Tlr5, Txnip, Ypel3 or downregulated Acat2, Brip1, Clspn, Dnajc25, Ercc6l, Mmd, Rif1, Zmpste24 whereas hypoxia alone led to a downregulation of most of the genes. Direct incubation at low pH reduced tumor cell adhesion whereas acidic pre-incubation increased the adhesive potential. In both tumor lines acidosis induced a G1-arrest (in vivo) of the cell cycle and a strong increase in necrotic cell death (but not in apoptosis). The mitochondrial O2 consumption increased gradually with decreasing pH. Conclusions These data show that acidic pHe in tumors plays an important role for gene expression independently from hypoxia. In parallel, acidosis modulates functional properties of tumors relevant for their malignant potential and which might be the result of pH-dependent gene expression.
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Affiliation(s)
- Mandy Rauschner
- Institute of Physiology, University Halle-Wittenberg, Magdeburger Str. 6, 06112, Halle (Saale), Germany
| | - Luisa Lange
- Institute of Physiology, University Halle-Wittenberg, Magdeburger Str. 6, 06112, Halle (Saale), Germany
| | - Thea Hüsing
- Institute of Physiology, University Halle-Wittenberg, Magdeburger Str. 6, 06112, Halle (Saale), Germany
| | - Sarah Reime
- Institute of Physiology, University Halle-Wittenberg, Magdeburger Str. 6, 06112, Halle (Saale), Germany
| | - Alexander Nolze
- Institute of Physiology, University Halle-Wittenberg, Magdeburger Str. 6, 06112, Halle (Saale), Germany
| | - Marcel Maschek
- Institute of Physiology, University Halle-Wittenberg, Magdeburger Str. 6, 06112, Halle (Saale), Germany
| | - Oliver Thews
- Institute of Physiology, University Halle-Wittenberg, Magdeburger Str. 6, 06112, Halle (Saale), Germany
| | - Anne Riemann
- Institute of Physiology, University Halle-Wittenberg, Magdeburger Str. 6, 06112, Halle (Saale), Germany.
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Riemann A, Reime S, Thews O. Acidic extracellular environment affects miRNA expression in tumorsin vitroandin vivo. Int J Cancer 2018; 144:1609-1618. [DOI: 10.1002/ijc.31790] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/13/2018] [Accepted: 07/23/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Anne Riemann
- Institute of PhysiologyUniversity Halle Halle (Saale) Germany
| | - Sarah Reime
- Institute of PhysiologyUniversity Halle Halle (Saale) Germany
| | - Oliver Thews
- Institute of PhysiologyUniversity Halle Halle (Saale) Germany
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Pinterić M, Podgorski II, Sobočanec S, Popović Hadžija M, Paradžik M, Dekanić A, Marinović M, Halasz M, Belužić R, Davidović G, Ambriović Ristov A, Balog T. De novo expression of transfected sirtuin 3 enhances susceptibility of human MCF-7 breast cancer cells to hyperoxia treatment. Free Radic Res 2018; 52:672-684. [PMID: 29683756 DOI: 10.1080/10715762.2018.1462495] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Sirtuin 3 (Sirt3) has a promising role in cancer tumourigenesis and treatment, but there have been controversies about its role as oncogene or tumour suppressor in different types of cancer. Changes in its expression are associated with the excessive production of reactive oxygen species (ROS), thus contributing to mitochondrial dysfunction and age-related pathologies. Hyperoxic treatment (i.e. generator of ROS) was shown to support some tumourigenic properties, but finally suppresses growth of certain mammary carcinoma cells. Due to strikingly reduced Sirt3 level in many breast cancer cell lines, we aimed to clarify the effect of de novo Sirt3 expression upon hyperoxic treatment in the human MCF-7 breast cancer cells. De novo expression of Sirt3 decreased metabolic activity and cellular growth of MCF-7 cells, reduced expression of proangiogenic and epithelial mesenchymal transition genes, induced metabolic switch from glycolysis to oxidative phosphorylation, and decreased abundance of senescent cells. These effects were enhanced upon hyperoxic treatment: induction of DNA damage and upregulation of p53, with an increase of ROS levels followed by mitochondrial and antioxidant dysfunction, resulted in additional reduction of metabolic activity and inhibition of cellular growth and survival. The mitigation of tumorigenic properties and enhancement of the susceptibility of the MCF-7 breast cancer cells to the hyperoxic treatment upon de novo Sirt3 expression indicates that these factors, individually and in combination, should be further explored in vitro and particularly in vivo, as an adjuvant tumour therapy in breast cancer malignancies.
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Affiliation(s)
- Marija Pinterić
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | - Iva I Podgorski
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | - Sandra Sobočanec
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | | | - Mladen Paradžik
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | - Ana Dekanić
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | - Maja Marinović
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | - Mirna Halasz
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | - Robert Belužić
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | - Grazia Davidović
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
| | | | - Tihomir Balog
- a Division of Molecular Medicine , Ruđer Bošković Institute , Zagreb , Croatia
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Riemann A, Reime S, Thews O. Tumor Acidosis and Hypoxia Differently Modulate the Inflammatory Program: Measurements In Vitro and In Vivo. Neoplasia 2017; 19:1033-1042. [PMID: 29149667 PMCID: PMC5695649 DOI: 10.1016/j.neo.2017.09.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/29/2017] [Accepted: 09/29/2017] [Indexed: 12/29/2022] Open
Abstract
Inflammatory mediators produced by the tumor cells are of importance for immune response but also for malignant progression. The aim of the study was to analyze the expression of monocyte chemoattractant protein-1, interleukin-6 (IL-6), tumor necrosis factor-α, inducible isoform of nitric oxide synthase (iNOS), cyclooxygenase-2, and osteopontin in vitro in two different tumor cell lines under hypoxia (pO2 ≈ 1.5 mmHg) and/or acidosis (pH = 6.6) for up to 24 hours since hypoxia and acidosis are common characteristics of solid tumors. Additionally, the same tumor cell lines implanted in vivo were made hypoxic and acidotic artificially for 24 hours, after which the cytokine expression was measured. Finally, the activation of ERK1/2 and p38 by acidosis/hypoxia and their impact on cytokine expression were studied. The results indicate that acidosis and hypoxia have fundamentally different (often opposing) effects on cytokine expression. In addition, these effects were tumor cell line specific. When combining hypoxia and acidosis, the overall changes reflect an additive effect of both conditions alone, indicating that hypoxia and acidosis act by independent mechanisms. The in vivo changes corresponded well with the results obtained in the isolated tumor cells. Only iNOS expression was downregulated in vivo but increased in cell culture. For IL-6 expression, the acidosis-induced changes were dependent on ERK1/2 activation. In conclusion, it was demonstrated that the environmental pO2 and pH strongly affect the expression of inflammatory mediators in tumor cells. In vivo, most of the inflammatory mediators were downregulated, which could limit the activation of immune cells and by this foster the immune escape of tumors.
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Affiliation(s)
- Anne Riemann
- Julius Bernstein Institute of Physiology, University Halle-Wittenberg, Germany.
| | - Sarah Reime
- Julius Bernstein Institute of Physiology, University Halle-Wittenberg, Germany
| | - Oliver Thews
- Julius Bernstein Institute of Physiology, University Halle-Wittenberg, Germany
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Maeda T, Suzuki A, Koga K, Miyamoto C, Maehata Y, Ozawa S, Hata RI, Nagashima Y, Nabeshima K, Miyazaki K, Kato Y. TRPM5 mediates acidic extracellular pH signaling and TRPM5 inhibition reduces spontaneous metastasis in mouse B16-BL6 melanoma cells. Oncotarget 2017; 8:78312-78326. [PMID: 29108231 PMCID: PMC5667964 DOI: 10.18632/oncotarget.20826] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/27/2017] [Indexed: 01/13/2023] Open
Abstract
Extracellular acidity is a hallmark of solid tumors and is associated with metastasis in the tumor microenvironment. Acidic extracellular pH (pH e ) has been found to increase intracellular Ca2+ and matrix metalloproteinase-9 (MMP-9) expression by activating NF-κB in the mouse B16 melanoma model. The present study assessed whether TRPM5, an intracellular Ca2+-dependent monovalent cation channel, is associated with acidic pH e signaling and induction of MMP-9 expression in this mouse melanoma model. Treatment of B16 cells with Trpm5 siRNA reduced acidic pH e -induced MMP-9 expression. Enforced expression of Trpm5 increased the rate of acidic pH e -induced MMP-9 expression, as well as increasing experimental lung metastasis. This genetic manipulation did not alter the pH e critical for MMP-9 induction but simply amplified the percentage of inducible MMP-9 at each pH e . Treatment of tumor bearing mice with triphenylphosphine oxide (TPPO), an inhibitor of TRPM5, significantly reduced spontaneous lung metastasis. In silico analysis of clinical samples showed that high TRPM5 mRNA expression correlated with poor overall survival rate in patients with melanoma and gastric cancer but not in patients with cancers of the ovary, lung, breast, and rectum. These results showed that TRPM5 amplifies acidic pH e signaling and may be a promising target for preventing metastasis of some types of tumor.
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Affiliation(s)
- Toyonobu Maeda
- Department of Oral Function and Molecular Biology, Ohu University School of Dentistry, Koriyama 963-8611, Japan
| | - Atsuko Suzuki
- Department of Oral Function and Molecular Biology, Ohu University School of Dentistry, Koriyama 963-8611, Japan
| | - Kaori Koga
- Department of Pathology, Fukuoka University School of Medicine and Hospital, Fukuoka 814-0180, Japan
| | - Chihiro Miyamoto
- Department of Oral Science, Kanagawa Dental University Graduate School of Dentistry, Yokosuka 238-8580, Japan
| | - Yojiro Maehata
- Department of Oral Science, Kanagawa Dental University Graduate School of Dentistry, Yokosuka 238-8580, Japan
| | - Shigeyuki Ozawa
- Department of Dentomaxillofacial Diagnosis and Treatment, Kanagawa Dental University Graduate School of Dentistry, Yokosuka 238-8580, Japan
| | - Ryu-Ichiro Hata
- Department of Dentomaxillofacial Diagnosis and Treatment, Kanagawa Dental University Graduate School of Dentistry, Yokosuka 238-8580, Japan
- Oral Health Science Research Center, Kanagawa Dental University Graduate School of Dentistry, Yokosuka 238-8580, Japan
| | - Yoji Nagashima
- Department of Surgical Pathology, Tokyo Women’s Medical University Hospital, Tokyo 162-8666, Japan
| | - Kazuki Nabeshima
- Department of Pathology, Fukuoka University School of Medicine and Hospital, Fukuoka 814-0180, Japan
| | - Kaoru Miyazaki
- Molecular Pathology and Genetics Division, Kanagawa Cancer Center Research Institute, Yokohama 241-8515, Japan
| | - Yasumasa Kato
- Department of Oral Function and Molecular Biology, Ohu University School of Dentistry, Koriyama 963-8611, Japan
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Horsman MR, Vaupel P. Pathophysiological Basis for the Formation of the Tumor Microenvironment. Front Oncol 2016; 6:66. [PMID: 27148472 PMCID: PMC4828447 DOI: 10.3389/fonc.2016.00066] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/07/2016] [Indexed: 12/27/2022] Open
Abstract
Poor microenvironmental conditions are a characteristic feature of solid tumors. Such conditions occur because the tumor vascular supply, which develops from the normal host vasculature by the process of angiogenesis, is generally inadequate in meeting the oxygen and nutrient demands of the growing tumor mass. Regions of low oxygenation (hypoxia) is believed to be the most critical deficiency, since it has been well documented to play a significant role in influencing the response to conventional radiation and chemotherapy treatments, as well as influencing malignant progression in terms of aggressive growth and recurrence of the primary tumor and its metastatic spread. As a result, significant emphasis has been placed on finding clinically applicable approaches to identify those tumors that contain hypoxia and realistic methods to target this hypoxia. However, most studies consider hypoxia as a single entity, yet we now know that it is multifactorial. Furthermore, hypoxia is often associated with other microenvironmental parameters, such as elevated interstitial fluid pressure, glycolysis, low pH, and reduced bioenergetic status, and these can also influence the effects of hypoxia. Here, we review the various aspects of hypoxia, but also discuss the role of the other microenvironmental parameters associated with hypoxia.
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Affiliation(s)
- Michael R Horsman
- Department of Experimental Clinical Oncology, Aarhus University Hospital , Aarhus , Denmark
| | - Peter Vaupel
- Department of Radiooncology and Radiotherapy, Klinikum rechts der Isar, Technische Universität München (TUM) , Munich , Germany
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13
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Payen VL, Porporato PE, Baselet B, Sonveaux P. Metabolic changes associated with tumor metastasis, part 1: tumor pH, glycolysis and the pentose phosphate pathway. Cell Mol Life Sci 2016; 73:1333-48. [PMID: 26626411 PMCID: PMC11108399 DOI: 10.1007/s00018-015-2098-5] [Citation(s) in RCA: 150] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/16/2015] [Accepted: 11/19/2015] [Indexed: 12/16/2022]
Abstract
Metabolic adaptations are intimately associated with changes in cell behavior. Cancers are characterized by a high metabolic plasticity resulting from mutations and the selection of metabolic phenotypes conferring growth and invasive advantages. While metabolic plasticity allows cancer cells to cope with various microenvironmental situations that can be encountered in a primary tumor, there is increasing evidence that metabolism is also a major driver of cancer metastasis. Rather than a general switch promoting metastasis as a whole, a succession of metabolic adaptations is more likely needed to promote different steps of the metastatic process. This review addresses the contribution of pH, glycolysis and the pentose phosphate pathway, and a companion paper summarizes current knowledge regarding the contribution of mitochondria, lipids and amino acid metabolism. Extracellular acidification, intracellular alkalinization, the glycolytic enzyme phosphoglucose isomerase acting as an autocrine cytokine, lactate and the pentose phosphate pathway are emerging as important factors controlling cancer metastasis.
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Affiliation(s)
- Valéry L Payen
- Pole of Pharmacology, Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain (UCL), Avenue Emmanuel Mounier 52, box B1.53.09, 1200, Brussels, Belgium
| | - Paolo E Porporato
- Pole of Pharmacology, Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain (UCL), Avenue Emmanuel Mounier 52, box B1.53.09, 1200, Brussels, Belgium
| | - Bjorn Baselet
- Pole of Pharmacology, Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain (UCL), Avenue Emmanuel Mounier 52, box B1.53.09, 1200, Brussels, Belgium
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK∙CEN, 2400, Mol, Belgium
| | - Pierre Sonveaux
- Pole of Pharmacology, Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain (UCL), Avenue Emmanuel Mounier 52, box B1.53.09, 1200, Brussels, Belgium.
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14
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Horsman MR. Realistic biological approaches for improving thermoradiotherapy. Int J Hyperthermia 2015; 32:14-22. [DOI: 10.3109/02656736.2015.1099169] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Prasad P, Gordijo CR, Abbasi AZ, Maeda A, Ip A, Rauth AM, DaCosta RS, Wu XY. Multifunctional albumin-MnO₂ nanoparticles modulate solid tumor microenvironment by attenuating hypoxia, acidosis, vascular endothelial growth factor and enhance radiation response. ACS NANO 2014; 8:3202-12. [PMID: 24702320 DOI: 10.1021/nn405773r] [Citation(s) in RCA: 435] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Insufficient oxygenation (hypoxia), acidic pH (acidosis), and elevated levels of reactive oxygen species (ROS), such as H2O2, are characteristic abnormalities of the tumor microenvironment (TME). These abnormalities promote tumor aggressiveness, metastasis, and resistance to therapies. To date, there is no treatment available for comprehensive modulation of the TME. Approaches so far have been limited to regulating hypoxia, acidosis, or ROS individually, without accounting for their interdependent effects on tumor progression and response to treatments. Hence we have engineered multifunctional and colloidally stable bioinorganic nanoparticles composed of polyelectrolyte-albumin complex and MnO2 nanoparticles (A-MnO2 NPs) and utilized the reactivity of MnO2 toward peroxides for regulation of the TME with simultaneous oxygen generation and pH increase. In vitro studies showed that these NPs can generate oxygen by reacting with H2O2 produced by cancer cells under hypoxic conditions. A-MnO2 NPs simultaneously increased tumor oxygenation by 45% while increasing tumor pH from pH 6.7 to pH 7.2 by reacting with endogenous H2O2 produced within the tumor in a murine breast tumor model. Intratumoral treatment with NPs also led to the downregulation of two major regulators in tumor progression and aggressiveness, that is, hypoxia-inducible factor-1 alpha and vascular endothelial growth factor in the tumor. Combination treatment of the tumors with NPs and ionizing radiation significantly inhibited breast tumor growth, increased DNA double strand breaks and cancer cell death as compared to radiation therapy alone. These results suggest great potential of A-MnO2 NPs for modulation of the TME and enhancement of radiation response in the treatment of cancer.
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Affiliation(s)
- Preethy Prasad
- Department of Pharmaceutical Sciences, Leslie L. Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
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16
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Offerman SC, Kamra Verma AV, Telfer BA, Berk DA, Clarke DJ, Aojula HS. Ability of co-administered peptide liposome nanoparticles to exploit tumour acidity for drug delivery. RSC Adv 2014. [DOI: 10.1039/c3ra44746d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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17
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Thews O, Riemann A, Nowak M, Gekle M. Impact of hypoxia-related tumor acidosis on cytotoxicity of different chemotherapeutic drugs in vitro and in vivo. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 812:51-58. [PMID: 24729214 DOI: 10.1007/978-1-4939-0620-8_7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Extracellular acidosis in tumors leads to an activation of the p-glycoprotein (Pgp) drug transporter. In the present study the cytotoxicity of different chemotherapeutic drugs and its dependence on the Pgp activity during acidosis were analyzed in vitro and in vivo. Treating R3327-AT1, Pgp-positive tumor cells at pH 7.4 with daunorubicin, cisplatin or docetaxel led to marked apoptosis induction and cell death. Under acidic (pH 6.6) conditions cytotoxicity of daunorubicin or docetaxel was significantly reduced whereas cisplatin-induced cell death was almost pH-independent. Inhibiting Pgp with verapamil reversed the acidosis-induced chemoresistance against daunorubicin and docetaxel. The Pgp expression was unaffected by pH. In vivo the cytotoxicity of daunorubicin and docetaxel was also pH dependent. When acidifying the tumors by forcing glycolytic metabolism, apoptosis induction decreased significantly indicating a reduced chemosensitivity. The cytotoxic effect of cisplatin in vivo was unaffected by the tumor pH. Since daunorubicin and docetaxel (but not cisplatin) are substrates of the Pgp, these results underline the influence of the tumor acidosis on the Pgp-mediated chemoresistance which can be counteracted by inhibition of the drug transporter.
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Affiliation(s)
- Oliver Thews
- Julius-Bernstein-Institute of Physiology, University of Halle, Halle (Saale), Germany.
| | - Anne Riemann
- Julius-Bernstein-Institute of Physiology, University of Halle, Halle (Saale), Germany
| | - Martin Nowak
- Institute of Physiology and Pathophysiology, University of Mainz, Mainz, Germany
| | - Michael Gekle
- Julius-Bernstein-Institute of Physiology, University of Halle, Halle (Saale), Germany
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18
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Thews O, Dillenburg W, Fellner M, Buchholz HG, Bausbacher N, Schreckenberger M, Rösch F. Activation of P-glycoprotein (Pgp)-mediated drug efflux by extracellular acidosis: in vivo imaging with 68Ga-labelled PET tracer. Eur J Nucl Med Mol Imaging 2010; 37:1935-42. [PMID: 20523987 DOI: 10.1007/s00259-010-1504-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 05/12/2010] [Indexed: 11/27/2022]
Abstract
PURPOSE In vitro it has been shown that the functional activity of P-glycoprotein (Pgp), an important drug transporter responsible for multidrug resistance, can be strongly increased by extracellular acidosis. Here mitogen-activated protein kinases (MAPK) (p38, ERK1/2) seem to play an important role for signal transduction. However, it is unclear whether these effects are also relevant in vivo. METHODS With the newly developed PET tracer Schiff base-based (68)Ga-MFL6.MZ the functional Pgp activity was visualized under acidic conditions and during inhibition of MAPKs non-invasively by means of microPET in rat tumours. Tumours were acidified either by inspiratory hypoxia (8% O(2)) or by injection of lactic acid. Inhibitors of the MAPK were injected intratumourally. RESULTS With increasing tumour volume the tumour pH changed from 7.0 to 6.7 and simultaneously the Pgp activity increased almost linearly. When the tumour was acidified by direct lactic acid injection the PET tracer uptake was reduced by 20% indicating a higher transport rate out of the cells. Changing the inspiratory O(2) fraction to 8% dynamically led to a reduction of extracellular pH and in parallel to a decrease of tracer concentration. While inhibition of the p38 pathway reduced the Pgp transport rate, inhibition of ERK1/2 had practically no impact. CONCLUSION An acidic extracellular environment significantly stimulates the Pgp activity. The p38 MAPK pathway plays an important role for Pgp regulation in vivo, whereas ERK1/2 is of minor importance. From these results new strategies for overcoming multidrug resistance (e.g. reducing tumour acidosis, inhibition of p38) may be developed.
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Affiliation(s)
- Oliver Thews
- Institute of Physiology and Pathophysiology, University Medicine Mainz, Duesbergweg 6, 55099 Mainz, Germany.
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19
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Yang AS, Chiang TC, Shen LH. Acute intravenous injection toxicity study of MIBG in mice. Drug Chem Toxicol 2009; 33:17-9. [DOI: 10.3109/01480540903130674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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20
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Silva AS, Yunes JA, Gillies RJ, Gatenby RA. The potential role of systemic buffers in reducing intratumoral extracellular pH and acid-mediated invasion. Cancer Res 2009; 69:2677-84. [PMID: 19276380 DOI: 10.1158/0008-5472.can-08-2394] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A number of studies have shown that the extracellular pH (pHe) in cancers is typically lower than that in normal tissue and that an acidic pHe promotes invasive tumor growth in primary and metastatic cancers. Here, we investigate the hypothesis that increased systemic concentrations of pH buffers reduce intratumoral and peritumoral acidosis and, as a result, inhibit malignant growth. Computer simulations are used to quantify the ability of systemic pH buffers to increase the acidic pHe of tumors in vivo and investigate the chemical specifications of an optimal buffer for such purpose. We show that increased serum concentrations of the sodium bicarbonate (NaHCO(3)) can be achieved by ingesting amounts that have been used in published clinical trials. Furthermore, we find that consequent reduction of tumor acid concentrations significantly reduces tumor growth and invasion without altering the pH of blood or normal tissues. The simulations also show that the critical parameter governing buffer effectiveness is its pK(a). This indicates that NaHCO(3), with a pK(a) of 6.1, is not an ideal intratumoral buffer and that greater intratumoral pHe changes could be obtained using a buffer with a pK(a) of approximately 7. The simulations support the hypothesis that systemic pH buffers can be used to increase the tumor pHe and inhibit tumor invasion.
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Affiliation(s)
- Ariosto S Silva
- Laboratório de Biologia Molecular, Centro Infantil Boldrini, Campinas, Sao Paulo, Brazil and Departments of Radiology and Integrative Mathematical Oncology, Moffitt Cancer Center, Tampa, Florida
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21
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Sauvant C, Nowak M, Wirth C, Schneider B, Riemann A, Gekle M, Thews O. Acidosis induces multi-drug resistance in rat prostate cancer cells (AT1) in vitro and in vivo by increasing the activity of the p-glycoprotein via activation of p38. Int J Cancer 2008; 123:2532-42. [PMID: 18729196 DOI: 10.1002/ijc.23818] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Because solid growing tumors often show hypoxia and pronounced extracellular acidosis, the aim of this study was to analyze the impact of an acidotic environment on the activity of the p-glycoprotein (pGP) and on the cellular content and cytotoxicity of the chemotherapeutic drug daunorubicin in the AT1 R-3327 Dunning prostate carcinoma cell line cultured in vitro and in vivo. In vitro, extracellular acidosis (pH 6.6) activated p38 and ERK1/2 and thereby induced daunorubicin resistance via a pronounced activation of pGP. De-novo protein synthesis was not necessary and analysis of transport kinetics indicated a fast and persistent pGP activation at pH 6.6 (when compared with 7.4). Intracellular acidification also induced daunorubicin resistance via activation of pGP, which was mediated by activation of p38 alone. In vivo, tumors were implanted subcutaneously, and the tumor pH was artificially lowered by forcing anaerobic metabolism. In vivo, the reduced extracellular pH of 6.6 was also able to induce daunorubicin resistance, which was abolished by inhibition of p38. These results suggest that pGP activity is dependent on extracellular pH in vitro and in vivo. Moreover, there is strong indication that this effect is mediated via activation of p38 in vivo. Activation of ERK is also suitable to induce pGP activity. Therefore, inhibition of p38 (and ERK) may be used to prevent acidosis induced increase in pGP activity and thereby attenuate multidrug resistance. In addition, supportive treatments reducing tumor acidosis may improve the cytotoxic effect of chemotherapeutic drugs.
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Holland JP, Barnard PJ, Collison D, Dilworth JR, Edge R, Green JC, McInnes EJL. Spectroelectrochemical and computational studies on the mechanism of hypoxia selectivity of copper radiopharmaceuticals. Chemistry 2008; 14:5890-907. [PMID: 18494010 DOI: 10.1002/chem.200800539] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Detailed chemical, spectroelectrochemical and computational studies have been used to investigate the mechanism of hypoxia selectivity of a range of copper radiopharmaceuticals. A revised mechanism involving a delicate balance between cellular uptake, intracellular reduction, reoxidation, protonation and ligand dissociation is proposed. This mechanism accounts for observed differences in the reported cellular uptake and washout of related copper bis(thiosemicarbazonato) complexes. Three copper and zinc complexes have been characterised by X-ray crystallography and the redox chemistry of a series of copper complexes has been investigated by using electronic absorption and EPR spectroelectrochemistry. Time-dependent density functional theory (TD-DFT) calculations have also been used to probe the electronic structures of intermediate species and assign the electronic absorption spectra. DFT calculations also show that one-electron oxidation is ligand-based, leading to the formation of cationic triplet species. In the absence of protons, metal-centred one-electron reduction gives the reduced anionic copper(I) species, [CuIATSM](-), and for the first time it is shown that molecular oxygen can reoxidise this anion to give the neutral, lipophilic parent complexes, which can wash out of cells. The electrochemistry is pH dependent and in the presence of stronger acids both chemical and electrochemical reduction leads to quantitative and rapid dissociation of copper(I) ions from the mono- or diprotonated complexes, [CuIATSMH] and [Cu(I)ATSMH2]+. In addition, a range of protonated intermediate species have been identified at lower acid concentrations. The one-electron reduction potential, rate of reoxidation of the copper(I) anionic species and ease of protonation are dependent on the structure of the ligand, which also governs their observed behaviour in vivo.
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Affiliation(s)
- Jason P Holland
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA (UK).
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23
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The tumor microenvironment and metastatic disease. Clin Exp Metastasis 2008; 26:19-34. [PMID: 18543068 DOI: 10.1007/s10585-008-9182-2] [Citation(s) in RCA: 215] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Accepted: 05/12/2008] [Indexed: 12/15/2022]
Abstract
The microenvironment of solid tumors is a heterogeneous, complex milieu for tumor growth and survival that includes features such as acidic pH, low nutrient levels, elevated interstitial fluid pressure (IFP) and chronic and fluctuating levels of oxygenation that relate to the abnormal vascular network that exists in tumors. The metastatic potential of tumor cells is believed to be regulated by interactions between the tumor cells and their extracellular environment (extracellular matrix (ECM)). These interactions can be modified by the accumulation of genetic changes and by the transient alterations in gene expression induced by the local tumor microenvironment. Clinical and experimental evidence suggests that altered gene expression in response to the hypoxic microenvironment is a contributing factor to increased metastatic efficiency. A number of genes that have been implicated in the metastatic process, involving angiogenesis, intra/extravasation, survival and growth, have been found to be hypoxia-responsive. The various metastatic determinants, genetic and epigenetic, somatic and inherited may serve as precedents for the future identification of more genes that are involved in metastasis. Much research has focused on genetic and molecular properties of the tumor cells themselves. In the present review we discuss the epigenetic and physiological regulation of metastasis and emphasize the need for further studies on the interactions between the pathophysiologic tumor microenvironment and the tumor extracellular matrix.
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Singh LS, Berk M, Oates R, Zhao Z, Tan H, Jiang Y, Zhou A, Kirmani K, Steinmetz R, Lindner D, Xu Y. Ovarian cancer G protein-coupled receptor 1, a new metastasis suppressor gene in prostate cancer. J Natl Cancer Inst 2007; 99:1313-27. [PMID: 17728215 DOI: 10.1093/jnci/djm107] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Metastasis is a process by which tumors spread from primary organs to other sites in the body and is the major cause of death for cancer patients. The ovarian cancer G protein-coupled receptor 1 (OGR1) gene has been shown to be expressed at lower levels in metastatic compared with primary prostate cancer tissues. METHODS We used an orthotopic mouse metastasis model, in which we injected PC3 metastatic human prostate cancer cells stably transfected with empty vector (vector-PC3) or OGR1-expressing vector (OGR1-PC3) into the prostate lobes of athymic or NOD/SCID mice (n = 3-8 mice per group). Migration of PC3 cells transiently transfected with vector control or with OGR1- or GPR4 (a G protein-coupled receptor with the highest homology to OGR1)-expressing vectors was measured in vitro by Boyden chamber assays. G protein alpha-inhibitory subunit 1 (G alpha(i1)) expression after treatment with pertussis toxin (PTX) was measured using immunoblotting analysis. The inhibitory factor present in the conditioned medium was extracted using organic solvents and analyzed by mass spectrometry. RESULTS In vivo, all 26 mice carrying tumors that were derived from vector-PC3 cells developed prostate cancer metastases (mean = 100%, 95% confidence interval [CI] = 83.97% to 100%) but few (4 of 32) mice carrying tumors derived from OGR1-expressing PC3 cells (mean = 12.50%, 95% CI = 4.08% to 29.93%) developed metastases. However, exogenous OGR1 overexpression had no effect on primary prostate tumor growth in vivo. In vitro, expression of OGR1, but not GPR4, inhibited cell migration (mean percentage of cells migrated, 30.2% versus 100%, difference = 69.8%, 95% CI = 63.0% to 75.9%; P<.001) via increased expression of G alpha(i1) and the secretion of a chloroform/methanol-extractable heat-insensitive factor into the conditioned medium through a PTX-sensitive pathway. CONCLUSION OGR1 is a novel metastasis suppressor gene for prostate cancer. OGR1's constitutive activity via G alpha(i) contributes to its inhibitory effect on cell migration in vitro.
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Affiliation(s)
- Lisam Shanjukumar Singh
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, 975 W. Walnut St, Indianapolis, IN 46202, USA
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Rofstad EK, Mathiesen B, Kindem K, Galappathi K. Acidic extracellular pH promotes experimental metastasis of human melanoma cells in athymic nude mice. Cancer Res 2006; 66:6699-707. [PMID: 16818644 DOI: 10.1158/0008-5472.can-06-0983] [Citation(s) in RCA: 477] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Extracellular pH (pH(e)) is lower in many tumors than in the corresponding normal tissue. The significance of acidic pH(e) in the development of metastatic disease was investigated in the present work. Human melanoma cells (A-07, D-12, and T-22) were cultured in vitro at pH(e) 6.8 or 7.4 (control) before being inoculated into the tail vein of BALB/c nu/nu mice for formation of experimental pulmonary metastases. Cell invasiveness was studied in vitro by using Matrigel invasion chambers and angiogenesis was studied in vivo by using an intradermal assay. Protein secretion was measured by ELISA and immunocapture assays. Cells cultured at acidic pH(e) showed increased secretion of proteinases and proangiogenic factors, enhanced invasive and angiogenic potential, and enhanced potential to develop experimental metastases. Acidity-induced metastasis was inhibited by treatment with the general matrix metalloproteinase (MMP) inhibitor GM6001, the general cysteine proteinase inhibitor E-64, or blocking antibody against vascular endothelial growth factor-A (VEGF-A) or interleukin-8 (IL-8). Our study indicates that acidic pH(e) promotes experimental pulmonary metastasis in A-07, D-12, and T-22 human melanoma cells by a common mechanism involving acidity-induced up-regulation of the proteolytic enzymes MMP-2, MMP-9, cathepsin B, and cathepsin L and acidity-induced up-regulation of the proangiogenic factors VEGF-A and IL-8. One consequence of this observation is that treatment strategies involving deliberate tumor acidification to improve the efficacy of chemotherapy, photodynamic therapy, and hyperthermia should be avoided. Moreover, the possibility that the pH(e) of the primary tumor may be an important prognostic parameter for melanoma patients merits clinical investigation.
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Affiliation(s)
- Einar K Rofstad
- Group of Radiation Biology and Tumor Physiology, Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, N-0310 Oslo, Norway.
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Cairns R, Papandreou I, Denko N. Overcoming physiologic barriers to cancer treatment by molecularly targeting the tumor microenvironment. Mol Cancer Res 2006; 4:61-70. [PMID: 16513837 DOI: 10.1158/1541-7786.mcr-06-0002] [Citation(s) in RCA: 260] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
It is widely recognized that the vasculature of the tumor is inadequate to meet the demands of the growing mass. The malformed vasculature is at least in part responsible for regions of the tumor that are hypoxic, acidotic, and exposed to increased interstitial fluid pressure. These unique aspects of the tumor microenvironment have been shown to act as barriers to conventional chemotherapy or radiation-based therapies. It now seems that while the vasculature initiates these tumor-specific conditions, the cells within the tumor respond to these stresses and add to the unique solid tumor physiology. Gene expression changes have been reported in the tumor for vascular endothelial growth factor, carbonic anhydrase IX, and pyruvate dehydrogenase kinase 1. The activity of these gene products then influences the tumor physiology through alterations in vascular permeability and interstitial fluid pressure, extracellular acidosis, and mitochondrial oxygen consumption and hypoxia, respectively. Novel molecular strategies designed to interfere with the activities of these gene products are being devised as ways to overcome the physiologic barriers in the tumor to standard anticancer therapies.
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Affiliation(s)
- Rob Cairns
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, CCSR-South, Room 1245, Stanford, CA 94305-5152, USA
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