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Nandy P, Mukherjee A, Pradhan C, Das S. Radio-Sensitizing Effects of Cu II and Zn II Complexes of Ornidazole: Role of Nitro Radical Anion. ACS OMEGA 2020; 5:25668-25676. [PMID: 33073092 PMCID: PMC7557252 DOI: 10.1021/acsomega.0c02811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 09/17/2020] [Indexed: 06/11/2023]
Abstract
The treatment of malignant cells that are deficient in oxygen due to the insufficient flow of blood is often seen as a major hindrance in radiotherapy. Such cells become radio-resistant because molecular oxygen, the natural and best radio-sensitizer, is depleted. Hence, to compensate this deficiency in oxygen, there is a need for agents that enhance radiation-induced damage of cells (radio-sensitizers) in a manner that normal cells are least affected. Simultaneously, agents capable of showing activity under hypoxic conditions are known as hypoxic cytotoxins that selectively and preferably destroy cells under hypoxic environments. 5-Nitroimidazoles fit both definitions. Their efficiency is based on their ability to generate the nitro radical anion that interacts with the strands of DNA within cells, either damaging or modifying them, leading to cell death. 5-Nitroimidazoles are important radio-pharmaceuticals (radio-sensitizers) in cancer-related treatments where the nitro radical anion has an important role. Since its generation leads to neurotoxic side effects that may be controlled through metal complex formation, this study looks at the possibility of two monomeric complexes of Ornidazole [1-chloro-3-(2-methyl-5-nitro-1H-imidazole-1-yl)propan-2-ol] with CuII and ZnII to be better radio-sensitizers and/or hypoxic cytotoxins than Ornidazole. The study reveals that although there is a decrease in nitro radical anion formation by complexes, such a decrease does not hamper their radio-sensitizing ability. Nucleic acid bases (thymine, cytosine, and adenine) or calf thymus DNA used as targets were irradiated with 60Co γ rays either in the absence or presence of Ornidazole and its monomeric complexes. Radiation-induced damage of nucleic acid bases was followed by high-performance liquid chromatography (HPLC), and modification of calf thymus DNA was followed by ethidium bromide fluorescence. Studies indicate that the complexes were better in performance than Ornidazole. CuII-ornidazole was significantly better than either Ornidazole or ZnII-ornidazole, which is attributed to certain special features of the CuII complex; aspects like having a stable lower oxidation state enable it to participate in Fenton reactions that actively influence radio-sensitization and the ability of the complex to bind effectively to DNA.
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Affiliation(s)
| | | | | | - Saurabh Das
- . . Tel: +91
33 2457 2148, Mobile: +91 8902087756. Fax: +91 33 2414 6223
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Zhong S, Jeong JH, Chen Z, Chen Z, Luo JL. Targeting Tumor Microenvironment by Small-Molecule Inhibitors. Transl Oncol 2019; 13:57-69. [PMID: 31785429 PMCID: PMC6909103 DOI: 10.1016/j.tranon.2019.10.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 12/12/2022] Open
Abstract
The tumor microenvironment (TME) is a hypoxic, acidic, and immune/inflammatory cell–enriched milieu that plays crucial roles in tumor development, growth, progression, and therapy resistance. Targeting TME is an attractive strategy for the treatment of solid tumors. Conventional cancer chemotherapies are mostly designed to directly kill cancer cells, and the effectiveness is always compromised by their penetration and accessibility to cancer cells. Small-molecule inhibitors, which exhibit good penetration and accessibility, are widely studied, and many of them have been successfully applied in clinics for cancer treatment. As TME is more penetrable and accessible than tumor cells, a lot of efforts have recently been made to generate small-molecule inhibitors that specifically target TME or the components of TME or develop special drug-delivery systems that release the cytotoxic drugs specifically in TME. In this review, we briefly summarize the recent advances of small-molecule inhibitors that target TME for the tumor treatment. Tumor microenvironment (TME) is an indispensable part of tumor and is an important therapeutic target. TME is more penetrable and accessible than tumor cell area. Small-molecule inhibitors that target TME are very promising. The target efficiency can be improved by specific deliver and release systems.
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Affiliation(s)
- Shangwei Zhong
- The Hunan Provincial Key Lab of Precision Diagnosis and Treatment for Gastrointestinal Tumor, Xiangya Hospital, Central South University, Hunan, 410008, China; Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Ji-Hak Jeong
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Zhikang Chen
- The Hunan Provincial Key Lab of Precision Diagnosis and Treatment for Gastrointestinal Tumor, Xiangya Hospital, Central South University, Hunan, 410008, China.
| | - Zihua Chen
- The Hunan Provincial Key Lab of Precision Diagnosis and Treatment for Gastrointestinal Tumor, Xiangya Hospital, Central South University, Hunan, 410008, China.
| | - Jun-Li Luo
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA.
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Shah VM, Nguyen DX, Al Fatease A, Patel P, Cote B, Woo Y, Gheewala R, Pham Y, Huynh MG, Gannett C, Rao DA, Alani AWG. Liposomal formulation of hypoxia activated prodrug for the treatment of ovarian cancer. J Control Release 2018; 291:169-183. [PMID: 30339904 DOI: 10.1016/j.jconrel.2018.10.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 10/08/2018] [Accepted: 10/16/2018] [Indexed: 02/06/2023]
Abstract
In this work, a new sphingomyelin-cholesterol liposomal formulation (CPD100Li) for the delivery of a hypoxia activated prodrug of vinblastine, mon-N-oxide (CPD100), is developed. The optimized liposomal formulation uses an ionophore (A23187) mediated pH-gradient method. Optimized CPD100Li is characterized for size, drug loading, and stability. The in vitro toxicity of CPD100Li is assessed on different aspects of cell proliferation and apoptosis of ES2 ovarian cancer under normoxic and hypoxic conditions. The pharmacokinetics of CPD100Li in mice as well as the influence of A23187 on the retention of CPD100 are assessed. The dose limiting toxicity (DLT) and maximum tolerated dose (MTD) for CPD100Li are evaluated in nude mice. CPD100 is loaded in the liposome at 5.5 mg/mL. The sizes of CPD100Li using DLS, qNano and cryo-TEM techniques are 155.4 ± 4.2 nm, 132 nm, and 112.6 ± 19.8 nm, respectively. There is no difference between the in vitro characterization of CPD100Li with and without ionophore. Freshly prepared CPD100Li with ionophore are stable for 48 h at 4 °C, while the freeze-dried formulation is stable for 3 months under argon at 4 °C. The hypoxic cytotoxicity ratios (HCR) of CPD100 and CPD100Li are 0.16 and 0.11, respectively. CPD100Li under hypoxic conditions has a 9.2-fold lower IC50 value as compared to CPD100Li under normoxic conditions, confirming the hypoxia dependent activation of CPD100. CPD100Li treated ES2 cells show a time dependent enhanced cell death, along with caspase production and an increase in the number of cells in G0/G1 and higher cell arrest. The blood concentration profile of CPD100Li in mice without A23187 has a 12.6-fold lower area under the curve (AUC) and 1.6-fold lower circulation time compared to the CPD100Li with A23187. The DLT for both CPD100 and CPD100Li is 45 mg/kg and the MTD is 40 mg/kg in nude mice. Based on the preliminary data obtained, we clearly show that the presence of ionophore affects the in vivo stability of CPD100. CPD100Li presents a unique opportunity to develop a first-in-kind chemotherapy product based on achieving selective drug activation through the hypoxic physiologic microenvironment of solid tumors.
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Affiliation(s)
- Vidhi M Shah
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University/OHSU, Portland, OR, USA
| | - Duc X Nguyen
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University/OHSU, Portland, OR, USA
| | - Adel Al Fatease
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University/OHSU, Portland, OR, USA
| | | | - Brianna Cote
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University/OHSU, Portland, OR, USA
| | - Yeonhee Woo
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University/OHSU, Portland, OR, USA
| | | | - Yvonne Pham
- Portland State University, Portland, OR, USA
| | | | - Christen Gannett
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University/OHSU, Portland, OR, USA
| | - Deepa A Rao
- School of Pharmacy, Pacific University, Hillsboro, OR, USA
| | - Adam W G Alani
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University/OHSU, Portland, OR, USA.
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Ivey JW, Bonakdar M, Kanitkar A, Davalos RV, Verbridge SS. Improving cancer therapies by targeting the physical and chemical hallmarks of the tumor microenvironment. Cancer Lett 2016; 380:330-9. [PMID: 26724680 PMCID: PMC4919249 DOI: 10.1016/j.canlet.2015.12.019] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 12/18/2022]
Abstract
Tumors are highly heterogeneous at the patient, tissue, cellular, and molecular levels. This multi-scale heterogeneity poses significant challenges for effective therapies, which ideally must not only distinguish between tumorous and healthy tissue, but also fully address the wide variety of tumorous sub-clones. Commonly used therapies either leverage a biological phenotype of cancer cells (e.g. high rate of proliferation) or indiscriminately kill all the cells present in a targeted volume. Tumor microenvironment (TME) targeting represents a promising therapeutic direction, because a number of TME hallmarks are conserved across different tumor types, despite the underlying genetic heterogeneity. Historically, TME targeting has largely focused on the cells that support tumor growth (e.g. vascular endothelial cells). However, by viewing the intrinsic physical and chemical alterations in the TME as additional therapeutic opportunities rather than barriers, a new class of TME-inspired treatments has great promise to complement or replace existing therapeutic strategies. In this review we summarize the physical and chemical hallmarks of the TME, and discuss how these tumor characteristics either currently are, or may ultimately be targeted to improve cancer therapies.
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Affiliation(s)
- Jill W Ivey
- Department of Biomedical Engineering and Mechanics, Virginia Tech-Wake Forest University, Blacksburg, VA 24061, USA
| | - Mohammad Bonakdar
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Akanksha Kanitkar
- Department of Biomedical Engineering and Mechanics, Virginia Tech-Wake Forest University, Blacksburg, VA 24061, USA
| | - Rafael V Davalos
- Department of Biomedical Engineering and Mechanics, Virginia Tech-Wake Forest University, Blacksburg, VA 24061, USA; Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Scott S Verbridge
- Department of Biomedical Engineering and Mechanics, Virginia Tech-Wake Forest University, Blacksburg, VA 24061, USA.
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Liew SY, Stanbridge EJ, Yusoff K, Shafee N. Hypoxia affects cellular responses to plant extracts. JOURNAL OF ETHNOPHARMACOLOGY 2012; 144:453-6. [PMID: 23022321 DOI: 10.1016/j.jep.2012.09.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Revised: 09/04/2012] [Accepted: 09/16/2012] [Indexed: 05/22/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Microenvironmental conditions contribute towards varying cellular responses to plant extract treatments. Hypoxic cancer cells are known to be resistant to radio- and chemo-therapy. New therapeutic strategies specifically targeting these cells are needed. Plant extracts used in Traditional Chinese Medicine (TCM) can offer promising candidates. Despite their widespread usage, information on their effects in hypoxic conditions is still lacking. In this study, we examined the cytotoxicity of a series of known TCM plant extracts under normoxic versus hypoxic conditions. MATERIALS AND METHODS Pereskia grandifolia, Orthosiphon aristatus, Melastoma malabathricum, Carica papaya, Strobilanthes crispus, Gynura procumbens, Hydrocotyle sibthorpioides, Pereskia bleo and Clinacanthus nutans leaves were dried, blended into powder form, extracted in methanol and evaporated to produce crude extracts. Human Saos-2 osteosarcoma cells were treated with various concentrations of the plant extracts under normoxia or hypoxia (0.5% oxygen). 24h after treatment, an MTT assay was performed and the IC(50) values were calculated. Effect of the extracts on hypoxia inducible factor (HIF) activity was evaluated using a hypoxia-driven firefly luciferase reporter assay. RESULTS The relative cytotoxicity of each plant extract on Saos-2 cells was different in hypoxic versus normoxic conditions. Hypoxia increased the IC(50) values for Pereskia grandifola and Orthosiphon aristatus extracts, but decreased the IC(50) values for Melastoma malabathricum and Carica papaya extracts. Extracts of Strobilanthes crispus, Gynura procumbens, Hydrocotyle sibthorpioides had equivalent cytotoxic effects under both conditions. Pereskia bleo and Clinacanthus nutans extracts were not toxic to cells within the concentration ranges tested. The most interesting result was noted for the Carica papaya extract, where its IC(50) in hypoxia was reduced by 3-fold when compared to the normoxic condition. This reduction was found to be associated with HIF inhibition. CONCLUSION Hypoxia variably alters the cytotoxic effects of TCM plant extracts on cancer cells. Carica papaya showed enhanced cytotoxic effect on hypoxic cancer cells by inhibiting HIF activities. These findings provide a plausible approach to killing hypoxic cancer cells in solid tumors.
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Affiliation(s)
- Sien-Yei Liew
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
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Bonnitcha PD, Kim BJ, Hocking RK, Clegg JK, Turner P, Neville SM, Hambley TW. Cobalt complexes with tripodal ligands: implications for the design of drug chaperones. Dalton Trans 2012; 41:11293-304. [PMID: 22885674 DOI: 10.1039/c2dt30727h] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Extensive research is currently being conducted into metal complexes that can selectively deliver cytotoxins to hypoxic regions in tumours. The development of pharmacologically suitable agents requires an understanding of appropriate ligand-metal systems for chaperoning cytotoxins. In this study, cobalt complexes with tripodal tren (tris-(2-aminoethyl)amine) and tpa (tris-(2-pyridylmethyl)amine) ligands were prepared with ancillary hydroxamic acid, β-diketone and catechol ligands and several parameters, including: pK(a), reduction potential and cytotoxicity were investigated. Fluorescence studies demonstrated that only tpa complexes with β-diketones showed any reduction by ascorbate in situ and similarly, cellular cytotoxicity results demonstrated that ligation to cobalt masked the cytotoxicity of the ancillary groups in all complexes except the tpa diketone derivative [Co(naac)tpa](ClO(4))(2) (naac = 1-methyl-3-(2-naphthyl)propane-1,3-dione). Additionally, it was shown that the hydroxamic acid complexes could be isolated in both the hydroxamate and hydroximate form and the pK(a) values (5.3-8.5) reveal that the reversible protonation/deprotonation of the complexes occurs at physiologically relevant pHs. These results have clear implications for the future design of prodrugs using cobalt moieties as chaperones, providing a basis for the design of cobalt complexes that are both more readily reduced and more readily taken up by cells in hypoxic and acidic environments.
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Affiliation(s)
- Paul D Bonnitcha
- School of Chemistry, The University of Sydney, NSW 2006, Australia
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8
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Yasui H, Matsumoto S, Devasahayam N, Munasinghe JP, Choudhuri R, Saito K, Subramanian S, Mitchell JB, Krishna MC. Low-field magnetic resonance imaging to visualize chronic and cycling hypoxia in tumor-bearing mice. Cancer Res 2010; 70:6427-36. [PMID: 20647318 DOI: 10.1158/0008-5472.can-10-1350] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Tumors exhibit fluctuations in blood flow that influence oxygen concentrations and therapeutic resistance. To assist therapeutic planning and improve prognosis, noninvasive dynamic imaging of spatial and temporal variations in oxygen partial pressure (pO(2)) would be useful. Here, we illustrate the use of pulsed electron paramagnetic resonance imaging (EPRI) as a novel imaging method to directly monitor fluctuations in oxygen concentrations in mouse models. A common resonator platform for both EPRI and magnetic resonance imaging (MRI) provided pO(2) maps with anatomic guidance and microvessel density. Oxygen images acquired every 3 minutes for a total of 30 minutes in two different tumor types revealed that fluctuation patterns in pO(2) are dependent on tumor size and tumor type. The magnitude of fluctuations in pO(2) in SCCVII tumors ranged between 2- to 18-fold, whereas the fluctuations in HT29 xenografts were of lower magnitude. Alternating breathing cycles with air or carbogen (95% O(2) plus 5% CO(2)) distinguished higher and lower sensitivity regions, which responded to carbogen, corresponding to cycling hypoxia and chronic hypoxia, respectively. Immunohistochemical analysis suggests that the fluctuation in pO(2) correlated with pericyte density rather than vascular density in the tumor. This EPRI technique, combined with MRI, may offer a powerful clinical tool to noninvasively detect variable oxygenation in tumors.
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Affiliation(s)
- Hironobu Yasui
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland 20892-1002, USA
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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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Shahrzad S, Shirasawa S, Sasazuki T, Rak JW, Coomber BL. Low-dose metronomic cyclophosphamide treatment mediates ischemia-dependent K-ras mutation in colorectal carcinoma xenografts. Oncogene 2008; 27:3729-38. [DOI: 10.1038/sj.onc.1211031] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Airley RE, Mobasheri A. Hypoxic regulation of glucose transport, anaerobic metabolism and angiogenesis in cancer: novel pathways and targets for anticancer therapeutics. Chemotherapy 2007; 53:233-56. [PMID: 17595539 DOI: 10.1159/000104457] [Citation(s) in RCA: 244] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Accepted: 05/09/2006] [Indexed: 12/15/2022]
Abstract
Cancer cells require a steady source of metabolic energy in order to continue their uncontrolled growth and proliferation. Accelerated glycolysis is one of the biochemical characteristics of cancer cells. Recent work indicates that glucose transport and metabolism are essential for the posttreatment survival of tumor cells, leading to poor prognosis. Glycolytic breakdown of glucose is preceded by the transport of glucose across the cell membrane, a rate-limiting process mediated by facilitative glucose transporter proteins belonging to the facilitative glucose transporter/solute carrier GLUT/SLC2A family. Tumors frequently show overexpression of GLUTs, especially the hypoxia-responsive GLUT1 and GLUT3 proteins. There are also studies that have reported associations between GLUT expression and proliferative indices, whilst others suggest that GLUT expression may be of prognostic significance. In this article we revisit Warburg's original hypothesis and review the recent clinical and basic research on the expression of GLUT family members in human cancers and in cell lines derived from human tumors. We also explore the links between hypoxia-induced genes, glucose transporters and angiogenic factors. Hypoxic tumors are significantly more malignant, metastatic, radio- and chemoresistant and have a poor prognosis. With the discovery the oxygen-sensitive transcription factor hypoxia-inducible factor (HIF-1) has come a new understanding of the molecular link between hypoxia and deregulated glucose metabolism. HIF-1 induces a number of genes integral to angiogenesis, e.g. vascular endothelial growth factor (VEGF), a process intimately involved with metastatic spread. This knowledge may enhance existing chemotherapeutic strategies so that treatment can be more rationally applied and personalized for cancer patients.
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Affiliation(s)
- Rachel E Airley
- Department of Developmental and Molecular Biology, Chanin Institute, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY, USA
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12
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Janaratne TK, Ongeri F, Yadav A, MacDonnell FM. Preferential DNA cleavage under anaerobic conditions by a DNA-binding ruthenium dimer. Inorg Chem 2007; 46:3420-2. [PMID: 17388584 PMCID: PMC2525620 DOI: 10.1021/ic0619714] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In the absence of dioxygen, the cationic complex [(phen)2Ru(tatpp)Ru(phen)2]4+ (P4+) undergoes in situ reduction by glutathione (GSH) to form a species that induces DNA cleavage. Exposure to air strongly attenuates the cleavage activity, even in the presence of a large excess of reducing agent (e.g., 40 equiv of GSH per P4+), suggesting that the complex may be useful in targeting cells with a low-oxygen microenvironment (hypoxia) for destruction via DNA cleavage. The active species is identified as the doubly reduced, doubly protonated complex H2P4+, and a carbon-based radical species is implicated in the cleavage action. We postulate that the dioxygen concentration regulates the degree to which the carbon radical forms and thus regulates the DNA cleavage activity.
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13
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Haffty BG, Wilson LD, Son YH, Cho EI, Papac RJ, Fischer DB, Rockwell S, Sartorelli AC, Ross DA, Sasaki CT, Fischer JJ. Concurrent chemo-radiotherapy with mitomycin C compared with porfiromycin in squamous cell cancer of the head and neck: Final results of a randomized clinical trial. Int J Radiat Oncol Biol Phys 2005; 61:119-28. [PMID: 15629602 DOI: 10.1016/j.ijrobp.2004.07.730] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 07/23/2004] [Accepted: 07/23/2004] [Indexed: 11/18/2022]
Abstract
PURPOSE Previous randomized trials have shown a benefit with concurrent use of the hypoxic cell cytotoxin mitomycin C (MC) and radiation (RT) in the management of squamous cell cancer of the head and neck (SCCHN). We conducted a randomized trial comparing MC with porfiromycin (POR) in combination with RT in the management of SCCHN. METHODS AND MATERIALS Between 1992 and 1999, 128 patients with SCCHN were enrolled in this prospective randomized trial. Patients were stratified by management intent, and balanced with respect to stage and site of disease. They were randomized to receive MC (15 mg/M(2)) or POR (40 mg/M(2)) on Days 5 and 47 (or last day) of RT. Of 121 evaluable patients, 61 were randomized to MC and 60 to POR. Patients were treated with standard daily RT to a total median dose of 64 Gy over 47 days. Patients were well balanced with respect to management intent, stage, site, age, sex, hemoglobin levels, tumor grade, radiation dose, and days on treatment. RESULTS There were no significant differences between the two arms with respect to acute hematologic or nonhematologic toxicities. As of January 2003 with a median follow-up of 6.3 years, there have been 19 local relapses (4 MC vs. 15 POR), 21 regional relapses (7 MC vs. 14 POR), 24 distant metastases (11 MC vs. 13 POR), and 66 deaths (33 MC vs. 33 POR). MC was superior to POR with respect to 5-year local relapse-free survival (91.6% vs. 72.7%, p = 0.01), local-regional relapse-free survival (82% vs. 65.3%, p = 0.05), and disease-free survival (72.8% vs. 52.9%, p = 0.026). There were no significant differences between the two arms with respect to overall survival (49.2% vs. 54.4%) or distant metastasis-free rate (79.9% vs. 75.9%). CONCLUSIONS Despite promising preclinical data, and an acceptable toxicity profile, POR was inferior to MC as an adjunct to RT in the management of SCCHN. This randomized trial emphasizes the need for randomized studies to evaluate new agents in the management of SCCHN.
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Affiliation(s)
- Bruce G Haffty
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA.
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Yu JL, Coomber BL, Kerbel RS. A paradigm for therapy-induced microenvironmental changes in solid tumors leading to drug resistance. Differentiation 2002; 70:599-609. [PMID: 12492501 DOI: 10.1046/j.1432-0436.2002.700913.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Intrinsic alterations in the tumor microenvironment are known to contribute to various forms of drug resistance. For example, tumor hypoxia, due to abnormal or sluggish blood flow within areas of solid tumors, can result in both microenvironment-mediated radiation and chemotherapeutic drug resistance. In contrast, acquired resistance to chemotherapy is generally considered to be the result of the gradual selection of mutant subpopulations having genetic mutations and biochemical alterations responsible for the resistant phenotype. Here we present a paradigm for therapyinduced microenvironment-mediated acquired drug resistance. It is based on the results showing that tumor cells appear to be heterogeneous in their relative dependence on adjacent tumor-associated vasculature for survival. Some tumor cells are highly vessel dependent, whereas some are significantly less so, and thus can survive in more hypoxic regions of tumors, distal from such tumor vessels. Hence, it is possible that variant tumor cells that are less vessel dependent may therefore be selected for over time by successful antiangiogenic drug therapies. This results in loss of response or attenuated responses to the therapy. Preliminary evidence is summarized in support of this hypothesis, using paired human colon cancer (HCT116) cell lines that contain two copies of either the wild-type or the disrupted p53 tumor suppressor gene. The mutant cells were found to be less responsive to antiangiogenic therapy, compared to the wild-type cells, and could be progressively selected for in mixed cell populations. Because p53 inactivation can lead to resistance to hypoxia-mediated apoptosis, the results suggest that a protracted and successful antiangiogenic therapy may create more hypoxic tumor microenvironments, thereby creating the necessary conditions to accelerate the selection of mutant tumor cells that are more adept in surviving and growing in such environments. As such, consideration might be given to the combined use of bioreductive hypoxic cell cytotoxic drugs and angiogenesis inhibitors to prolong the efficacy of antiangiogenic therapeutics.
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Affiliation(s)
- Joanne L Yu
- Molecular and Cell Biology Research, Sunnybrook and Women's college Health Sciences Centre, Toronto, ON, Canada
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Yu JL, Rak JW, Coomber BL, Hicklin DJ, Kerbel RS. Effect of p53 status on tumor response to antiangiogenic therapy. Science 2002; 295:1526-8. [PMID: 11859195 DOI: 10.1126/science.1068327] [Citation(s) in RCA: 342] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The p53 tumor suppressor gene is inactivated in the majority of human cancers. Tumor cells deficient in p53 display a diminished rate of apoptosis under hypoxic conditions, a circumstance that might reduce their reliance on vascular supply, and hence their responsiveness to antiangiogenic therapy. Here, we report that mice bearing tumors derived from p53(-/-) HCT116 human colorectal cancer cells were less responsive to antiangiogenic combination therapy than mice bearing isogenic p53(+/+) tumors. Thus, although antiangiogenic therapy targets genetically stable endothelial cells in the tumor vasculature, genetic alterations that decrease the vascular dependence of tumor cells can influence the therapeutic response of tumors to this therapy.
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Affiliation(s)
- Joanne L Yu
- Sunnybrook and Women's College Health Sciences Centre, Molecular and Cellular Biology Research, Room S-218, 2075 Bayview Avenue, Toronto, Ontario, Canada M4N 3M5
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Park SY, Billiar TR, Seol DW. Hypoxia inhibition of apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Biochem Biophys Res Commun 2002; 291:150-3. [PMID: 11829475 DOI: 10.1006/bbrc.2002.6421] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypoxia is a common environmental stress. Particularly, the center of rapidly growing solid tumors is easily exposed to hypoxic conditions. Thus, tumor cell response to hypoxia plays an important role in tumor progression as well as tumor therapy. However, little is known about hypoxic effect on apoptotic cell death. To examine the effects of hypoxia on TRAIL-induced apoptosis, human lung carcinoma A549 cells were exposed to hypoxia and treated with TRAIL protein. Hypoxia significantly protected A549 cells from apoptosis induced by TRAIL. Western blotting analysis demonstrated that hypoxia increased expression of antiapoptotic proteins such as Bcl-2, Bcl-XL, and IAP family members. The increase of these antiapoptotic molecules is believed to play an hypoxia-mediated protective role in TRAIL-induced apoptosis. Our findings suggest that an increase of antiapoptotic proteins induced by hypoxia may regulate the therapeutic activity of TRAIL protein in cancer therapy.
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Affiliation(s)
- Sang-Youel Park
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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Teicher BA. Molecular targets and cancer therapeutics: discovery, development and clinical validation. Drug Resist Updat 2000; 3:67-73. [PMID: 11498368 DOI: 10.1054/drup.2000.0123] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics held in Washington, DC on 16-19 November 1999 provided a forum for cancer research clearly showing evolution of a target and mechanism-driven science. The notion of the tumor as a tissue composed of heterogeneous populations of normal and abnormal cells as viable targets is coming to the fore with the advent of agents directed toward non-malignant cell targets. Growth control rather than eradication as a treatment strategy for malignant disease is being tested preclinically and clinically. Among targets, kinases are in the lead with nuclear, cytoplasmic and membrane kinases being selectively inhibited by small molecules and macromolecules. First generation tumor vasculature-directed agents are progressing through early clinical studies. The interest in tumor vasculature as a target has renewed interest in imaging technology to discern biological effect and in tumor hypoxia. This has resulted in elucidation of molecular responses triggered by a low oxygen environment. Challenges remain in the areas of cellular and immune therapies. Dendritic cell-based vaccines are being tested preclinically in many systems. Interleukin-12 is proceeding through clinical trials. Apoptosis-protective molecules such as bcl-2, and apoptosis-stimulating molecules such as bax, are being pursued as targets for inhibition and activation, respectively. Finally, methods and technology to aid in the identification of new targets were highlighted. This perspective, while it is by no means an exhaustive review of the presentations, brings forward some of the main topics and interests that are current in cancer research. Targets were the topic but methods of target identification and the need for increased chemical diversity to selectively focus agents to targets with small differences were also major topics of discussion. Copyright 2000 Harcourt Publishers Ltd.
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Affiliation(s)
- Beverly A. Teicher
- Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN, USA
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