1
|
Hu A, Zhou W, Qiu R, Wei S, Wu Z, Zhang H, Li J. Computational model of radiation oxygen effect with Monte Carlo simulation: effects of antioxidants and peroxyl radicals. Int J Radiat Biol 2024; 100:595-608. [PMID: 38166197 DOI: 10.1080/09553002.2023.2295292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 11/20/2023] [Indexed: 01/04/2024]
Abstract
PURPOSE Oxygen plays a crucial role in radiation biology. Antioxidants and peroxyl radicals affect the oxygen effect greatly. This study aims to establish a computational model of the oxygen effect and explore the effect attributed to antioxidants and peroxyl radicals. MATERIALS AND METHODS Oxygen-related reactions are added to our track-structure Monte Carlo code NASIC, including oxygen fixation, chemical repair by antioxidants and damage migration from base-derived peroxyl radicals. Then the code is used to simulate the DNA damage under various oxygen, antioxidant and damage migration rate conditions. The oxygen enhancement ratio(OER) is calculated quantifying by the number of double-strand breaks for each condition. The roles of antioxidants and peroxyl radicals are examined by manipulating the relevant parameters. RESULTS AND CONCLUSIONS Our results indicate that antioxidants are capable of rapidly restoring DNA radicals through chemical reactions, which compete with natural and oxygen fixation processes. Additionally, antioxidants can react with peroxyl radicals derived from bases, thereby preventing the damage from migrating to DNA strands. By quantitatively accounting for the impact of peroxyl radicals and antioxidants on the OER curves, our study establishes a more precise and comprehensive model of the radiation oxygen effect.
Collapse
Affiliation(s)
- Ankang Hu
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, China
| | - Wanyi Zhou
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, China
| | - Rui Qiu
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, China
| | - Shuoyang Wei
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, China
| | - Zhen Wu
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Nuctech Company Limited, Beijing, China
| | - Hui Zhang
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, China
| | - Junli Li
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, China
| |
Collapse
|
2
|
Wardman P. Approaches to modeling chemical reaction pathways in radiobiology. Int J Radiat Biol 2022; 98:1399-1413. [DOI: 10.1080/09553002.2022.2033342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Peter Wardman
- 20 Highover Park, Amersham, Buckinghamshire HP7 0BN, United Kingdom
| |
Collapse
|
3
|
Therapeutic targeting of the hypoxic tumour microenvironment. Nat Rev Clin Oncol 2021; 18:751-772. [PMID: 34326502 DOI: 10.1038/s41571-021-00539-4] [Citation(s) in RCA: 165] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2021] [Indexed: 02/07/2023]
Abstract
Hypoxia is prevalent in human tumours and contributes to microenvironments that shape cancer evolution and adversely affect therapeutic outcomes. Historically, two different tumour microenvironment (TME) research communities have been discernible. One has focused on physicochemical gradients of oxygen, pH and nutrients in the tumour interstitium, motivated in part by the barrier that hypoxia poses to effective radiotherapy. The other has focused on cellular interactions involving tumour and non-tumour cells within the TME. Over the past decade, strong links have been established between these two themes, providing new insights into fundamental aspects of tumour biology and presenting new strategies for addressing the effects of hypoxia and other microenvironmental features that arise from the inefficient microvascular system in solid tumours. This Review provides a perspective on advances at the interface between these two aspects of the TME, with a focus on translational therapeutic opportunities relating to the elimination and/or exploitation of tumour hypoxia.
Collapse
|
4
|
Wardman P. Radiotherapy Using High-Intensity Pulsed Radiation Beams (FLASH): A Radiation-Chemical Perspective. Radiat Res 2020; 194:607-617. [DOI: 10.1667/rade-19-00016] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/31/2020] [Indexed: 11/03/2022]
|
5
|
Koch CJ. A Two-Component Assay for Hypoxia Incorporating Long-Term Nitroreduction and Short-Term DNA-Damage Allows Differentiation of the Three Hypoxia Sub-types. Radiat Res 2018; 190:72-87. [PMID: 29746214 DOI: 10.1667/rr15029.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Hypoxia in tumors has many well-characterized effects that are known to prevent optimal cancer treatment. Despite the existence of a large number of assays that have supported hypoxia as an important diagnostic, there is no routine clinical assay in use, and anti-hypoxia therapies have often not included parallel hypoxia measurements. Even with a functioning hypoxia assay, it is difficult to match the oxygen dependence of treatment resistance to that of the assay, and this mismatch can vary substantially from assay to assay and even from tumor to tumor [e.g., caused by endogenous variations in non-protein sulfhydryls (NPSH)]. An underlying concern is the current inability to measure the three types of hypoxia; in particular, cycling hypoxia can affect all aspects of detection and treatment strategy. Here we present data that help validate a new two-component hypoxia assay recently suggested by our laboratory. This assay incorporates the long-term bioreduction of the 2-nitroimidazole, EF5, and the short-term production of γ-H2AX (e.g., time of ionizing radiation exposure). The former can be calibrated to provide the average tissue pO2 over the EF5 exposure time while the latter provides the combined sum of microenvironmental radiation response modifiers (e.g., oxygen and NPSH) at the time of irradiation. Importantly, formation of γ-H2AX is not dependent on blood flow, while EF5 binding is only minimally so, due to the rapid and extensive diffusion characteristics of lipophilic compounds. While both individual assays have their limitations, which are addressed in this article, their combination can dissect the type of hypoxia present. In particular, a mismatch between the two assays can directly detect cycling hypoxia in a therapeutically relevant manner. Preliminary use of this two-component assay in small PC3 tumors showed essentially no binding of EF5. Similarly, there were no tumor regions (for uniform irradiation with 12 Gy) with the low levels of γ-H2AX expected for a condition of cycling hypoxia. Thus, both assays were consistent with an essentially aerobic, radiation-responsive tumor. In a larger PC3 tumor, all regions of high EF5 binding had low levels of γ-H2AX.
Collapse
Affiliation(s)
- Cameron J Koch
- Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6072
| |
Collapse
|
6
|
Molecular targeting of hypoxia in radiotherapy. Adv Drug Deliv Rev 2017; 109:45-62. [PMID: 27771366 DOI: 10.1016/j.addr.2016.10.002] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 10/02/2016] [Accepted: 10/15/2016] [Indexed: 12/21/2022]
Abstract
Hypoxia (low O2) is an essential microenvironmental driver of phenotypic diversity in human solid cancers. Hypoxic cancer cells hijack evolutionarily conserved, O2- sensitive pathways eliciting molecular adaptations that impact responses to radiotherapy, tumor recurrence and patient survival. In this review, we summarize the radiobiological, genetic, epigenetic and metabolic mechanisms orchestrating oncogenic responses to hypoxia. In addition, we outline emerging hypoxia- targeting strategies that hold promise for individualized cancer therapy in the context of radiotherapy and drug delivery.
Collapse
|
7
|
Abstract
Tumours contain multiple different cell populations, including cells derived from the bone marrow as well as cancer-associated fibroblasts and various stromal populations including the vasculature. The microenvironment of the tumour cells plays a significant role in the response of the tumour to radiation treatment. Low levels of oxygen (hypoxia) caused by the poorly organized vasculature in tumours have long been known to affect radiation response; however, other aspects of the microenvironment may also play important roles. This article reviews some of the old literature concerning tumour response to irradiation and relates this to current concepts about the role of the tumour microenvironment in tumour response to radiation treatment. Included in the discussion are the role of cancer stem cells, radiation damage to the vasculature and the potential for radiation to enhance immune activity against tumour cells. Radiation treatment can cause a significant influx of bone marrow-derived cell populations into both normal tissues and tumours. Potential roles of such cells may include enhancing vascular recovery as well as modulating immune reactivity.
Collapse
Affiliation(s)
- Richard P Hill
- 1 Ontario Cancer Institute, Princess Margaret Cancer Centre, Toronto, ON, Canada.,2 Departments of Medical Biophysics and Radiation Oncology, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
8
|
Jiang Y, Wu GH, He GD, Zhuang QL, Xi QL, Zhang B, Han YS, Fang J. The Effect of Silencing HIF-1α Gene in BxPC-3 Cell Line on Glycolysis-Related Gene Expression, Cell Growth, Invasion, and Apoptosis. Nutr Cancer 2015; 67:1314-23. [DOI: 10.1080/01635581.2015.1085584] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
9
|
|
10
|
Lao Z, Kelly CJ, Yang XY, Jenkins WT, Toorens E, Ganguly T, Evans SM, Koch CJ. Improved Methods to Generate Spheroid Cultures from Tumor Cells, Tumor Cells & Fibroblasts or Tumor-Fragments: Microenvironment, Microvesicles and MiRNA. PLoS One 2015. [PMID: 26208323 PMCID: PMC4514828 DOI: 10.1371/journal.pone.0133895] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Diagnostic and prognostic indicators are key components to achieve the goal of personalized cancer therapy. Two distinct approaches to this goal include predicting response by genetic analysis and direct testing of possible therapies using cultures derived from biopsy specimens. Optimally, the latter method requires a rapid assessment, but growing xenograft tumors or developing patient-derived cell lines can involve a great deal of time and expense. Furthermore, tumor cells have much different responses when grown in 2D versus 3D tissue environments. Using a modification of existing methods, we show that it is possible to make tumor-fragment (TF) spheroids in only 2–3 days. TF spheroids appear to closely model characteristics of the original tumor and may be used to assess critical therapy-modulating features of the microenvironment such as hypoxia. A similar method allows the reproducible development of spheroids from mixed tumor cells and fibroblasts (mixed-cell spheroids). Prior literature reports have shown highly variable development and properties of mixed-cell spheroids and this has hampered the detailed study of how individual tumor-cell components interact. In this study, we illustrate this approach and describe similarities and differences using two tumor models (U87 glioma and SQ20B squamous-cell carcinoma) with supporting data from additional cell lines. We show that U87 and SQ20B spheroids predict a key microenvironmental factor in tumors (hypoxia) and that SQ20B cells and spheroids generate similar numbers of microvesicles. We also present pilot data for miRNA expression under conditions of cells, tumors, and TF spheroids.
Collapse
Affiliation(s)
- Zheng Lao
- University of Pennsylvania, Perelman School of Medicine, Dept Radiation Oncology, Philadelphia, Pennsylvania, United States of America
- Fudan University, Eye & ENT Hospital, Dept Radiation Oncology, Shanghai, China
| | - Catherine J. Kelly
- Oxford University, Gray Institute for Radiation Oncology, Oxford, United Kingdom
| | - Xiang-Yang Yang
- University of Pennsylvania, Perelman School of Medicine, Dept Radiation Oncology, Philadelphia, Pennsylvania, United States of America
| | - W. Timothy Jenkins
- University of Pennsylvania, Perelman School of Medicine, Dept Radiation Oncology, Philadelphia, Pennsylvania, United States of America
| | - Erik Toorens
- University of Pennsylvania, Perelman School of Medicine, Penn Genomics Analysis Core, Philadelphia, Pennsylvania, United States of America
| | - Tapan Ganguly
- University of Pennsylvania, Perelman School of Medicine, Penn Genomics Analysis Core, Philadelphia, Pennsylvania, United States of America
| | - Sydney M. Evans
- University of Pennsylvania, Perelman School of Medicine, Dept Radiation Oncology, Philadelphia, Pennsylvania, United States of America
| | - Cameron J. Koch
- University of Pennsylvania, Perelman School of Medicine, Dept Radiation Oncology, Philadelphia, Pennsylvania, United States of America
- * E-mail:
| |
Collapse
|
11
|
Xu XD, Shao SX, Jiang HP, Cao YW, Wang YH, Yang XC, Wang YL, Wang XS, Niu HT. Warburg effect or reverse Warburg effect? A review of cancer metabolism. Oncol Res Treat 2015; 38:117-22. [PMID: 25792083 DOI: 10.1159/000375435] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/22/2015] [Indexed: 11/19/2022]
Abstract
Cancer is a major threat to human health. A considerable amount of research has focused on elucidating the nature of cancer from its pathogenesis to treatment and prevention. Tumor cell metabolism has been considered a hallmark of cancer. Cancer cells differ from normal cells through unlimited cell division, and show a greater need for energy for their rapid growth and duplication. Research on glycometabolism, as the key point of energy metabolism, has played a unique role. In the 1920s, Warburg found that cancer cells prefer to produce adenosine triphosphate (ATP) by glycolysis, which is a less efficient pathway compared to oxidative phosphorylation. This striking discovery, called 'the Warburg effect', has influenced and guided the study of the mechanism and treatment of tumors for generations, but its causal relationship with cancer progression is still unclear. Some studies have now shown contradicting evidence and a new hypothesis, the reverse Warburg effect, has been put forward, in which cancer cells produce most of their ATP via glycolysis, even under aerobic conditions. In this review we discuss the new points concerning the energy metabolism of a tumor, as well as the current facts and perspectives.
Collapse
Affiliation(s)
- Xiao Dong Xu
- The Key Laboratory of Urology, Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Xue G, Yan HL, Zhang Y, Hao LQ, Zhu XT, Mei Q, Sun SH. c-Myc-mediated repression of miR-15-16 in hypoxia is induced by increased HIF-2α and promotes tumor angiogenesis and metastasis by upregulating FGF2. Oncogene 2014; 34:1393-406. [PMID: 24704828 DOI: 10.1038/onc.2014.82] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 01/26/2014] [Accepted: 02/14/2014] [Indexed: 02/07/2023]
Abstract
Previous studies have established the link between aberrant microRNA (miRNA) expression and hypoxia in various neoplasms. However, how these hypoxia-related miRNAs modulate tumor progression is still unclear. Therefore, the patterns of miRNA in colorectal carcinoma cell lines in response to hypoxia or not were first screened and the hypoxia-induced repression of the miR-15-16 cluster was confirmed. Then, this repression was found to be associated with high tumor stage and poor prognosis in colorectal carcinoma and is shown to promote tumor angiogenesis and metastasis by the loss of restriction of its target gene, fibroblast growth factor-2 (FGF2). Moreover, the general and alterative promoters of the miR-15-16 host (deleted in lymphocytic leukemia 2, DLEU2) were mapped, and three c-Myc/Max binding sites in response to the hypoxia-induced repression of miR-15-16 were further identified. Finally, an enhanced stability of c-Myc/Max heterodimer promoted by increased hypoxia-inducible factor-2α (HIF-2α) was validated, and we also verified that the enhancement contributed to the hypoxia-induced repression of miR-15-16. In brief, the c-Myc-mediated transcriptional repression of miR-15-16 in hypoxia is induced by increased HIF-2α and promoted tumor angiogenesis and hematogenous metastasis by the further loss of post-transcriptional inhibition of FGF2. Our study provides a better understanding of the coping mechanisms in response to tumor hypoxia and may be helpful in developing an effective prognostic marker or treatment target against solid tumors.
Collapse
Affiliation(s)
- G Xue
- Department of Medical Genetics, College of Basic Medical Sciences, Second Military Medical University, Shanghai, China
| | - H-L Yan
- Department of Medical Genetics, College of Basic Medical Sciences, Second Military Medical University, Shanghai, China
| | - Y Zhang
- Department of Medical Genetics, College of Basic Medical Sciences, Second Military Medical University, Shanghai, China
| | - L-Q Hao
- Department of Colorectal Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - X-T Zhu
- Department of Medical Genetics, College of Basic Medical Sciences, Second Military Medical University, Shanghai, China
| | - Q Mei
- Department of Medical Genetics, College of Basic Medical Sciences, Second Military Medical University, Shanghai, China
| | - S-H Sun
- Department of Medical Genetics, College of Basic Medical Sciences, Second Military Medical University, Shanghai, China
| |
Collapse
|
13
|
Moreno-Sánchez R, Marín-Hernández A, Saavedra E, Pardo JP, Ralph SJ, Rodríguez-Enríquez S. Who controls the ATP supply in cancer cells? Biochemistry lessons to understand cancer energy metabolism. Int J Biochem Cell Biol 2014; 50:10-23. [PMID: 24513530 DOI: 10.1016/j.biocel.2014.01.025] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/21/2014] [Accepted: 01/26/2014] [Indexed: 11/17/2022]
Abstract
Applying basic biochemical principles, this review analyzes data that contrasts with the Warburg hypothesis that glycolysis is the exclusive ATP provider in cancer cells. Although disregarded for many years, there is increasing experimental evidence demonstrating that oxidative phosphorylation (OxPhos) makes a significant contribution to ATP supply in many cancer cell types and under a variety of conditions. Substrates oxidized by normal mitochondria such as amino acids and fatty acids are also avidly consumed by cancer cells. In this regard, the proposal that cancer cells metabolize glutamine for anabolic purposes without the need for a functional respiratory chain and OxPhos is analyzed considering thermodynamic and kinetic aspects for the reductive carboxylation of 2-oxoglutarate catalyzed by isocitrate dehydrogenase. In addition, metabolic control analysis (MCA) studies applied to energy metabolism of cancer cells are reevaluated. Regardless of the experimental/environmental conditions and the rate of lactate production, the flux-control of cancer glycolysis is robust in the sense that it involves the same steps: glucose transport, hexokinase, hexosephosphate isomerase and glycogen degradation, all at the beginning of the pathway; these steps together with phosphofructokinase 1 also control glycolysis in normal cells. The respiratory chain complexes exert significantly higher flux-control on OxPhos in cancer cells than in normal cells. Thus, determination of the contribution of each pathway to ATP supply and/or the flux-control distribution of both pathways in cancer cells is necessary in order to identify differences from normal cells which may lead to the design of rational alternative therapies that selectively target cancer energy metabolism.
Collapse
Affiliation(s)
- Rafael Moreno-Sánchez
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México D.F., Mexico.
| | - Alvaro Marín-Hernández
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México D.F., Mexico
| | - Emma Saavedra
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México D.F., Mexico
| | - Juan P Pardo
- Universidad Nacional Autónoma de México, Facultad de Medicina, Departamento de Bioquímica, México D.F., Mexico
| | - Stephen J Ralph
- School of Medical Sciences, Griffith University, Gold Coast Campus, Qld, Australia
| | - Sara Rodríguez-Enríquez
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México D.F., Mexico; Instituto Nacional de Cancerología, Laboratorio de Medicina Translacional, Tlalpan, México D.F., Mexico
| |
Collapse
|
14
|
Rodríguez-Enríquez S, Pacheco-Velázquez SC, Gallardo-Pérez JC, Marín-Hernández A, Aguilar-Ponce JL, Ruiz-García E, Ruizgodoy-Rivera LM, Meneses-García A, Moreno-Sánchez R. Multi-biomarker pattern for tumor identification and prognosis. J Cell Biochem 2012; 112:2703-15. [PMID: 21678471 DOI: 10.1002/jcb.23224] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In last decades, the basic, clinical, and translational research efforts have been directed to the identification of standard biomarkers associated with the degree of malignancy. There is an increasingly public health concern for earlier detection of cancer development at stages in which successful treatments can be achieved. To meet this urgent clinical demand, early stage cancer biomarkers supported by reliable and robust experimental data that can be readily applicable in the clinical practice, are required. In the current standard protocols, when one or two of the canonical proliferating index biomarkers are analyzed, contradictory results are frequently reached leading to incorrect cancer diagnostic and unsuccessful therapies. Therefore, the identification of other cellular characteristics or signatures present in the tumor cells either alone or in combination with the well-established proliferation markers emerge as an alternative strategy in the improvement of cancer diagnosis and treatment. Because it is well known that several pathways and processes are altered in tumor cells, the concept of "single marker" in cancer results incorrect. Therefore, this review aims to analyze and discuss the proposal that the molecular profile of different genes or proteins in different altered tumor pathways must be established to provide a better global clinical pattern for cancer detection and prognosis.
Collapse
|
15
|
Kikuchi M, Yamane T, Shinohara S, Fujiwara K, Hori SY, Tona Y, Yamazaki H, Naito Y, Senda M. 18F-fluoromisonidazole positron emission tomography before treatment is a predictor of radiotherapy outcome and survival prognosis in patients with head and neck squamous cell carcinoma. Ann Nucl Med 2011; 25:625-33. [PMID: 21720778 DOI: 10.1007/s12149-011-0508-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 06/07/2011] [Indexed: 01/06/2023]
Abstract
OBJECTIVE To evaluate the usefulness of [(18)F]fluoromisonidazole ([(18)F]FMISO)-positron emission tomography (PET) prior to the treatment of head and neck squamous cell carcinoma. METHODS Seventeen patients with untreated HNSCC underwent pretreatment [(18)F]FMISO PET. Six of them underwent definitive surgery and the remaining 11 definitive (chemo-)radiotherapy. We evaluated 30 lesions from the 17 patients. SUVmax and tumor-to-muscle ratios (TMR) were measured as hypoxia indicators. Tumors equal to or above the median value were defined as tumor with high uptake of [(18)F]FMISO and those below as tumor with low uptake of [(18)F]FMISO in both indicators. Local control rates with radiotherapy, event-free survival and disease-specific survival (DSS) rates with radiotherapy or operation were compared. RESULT [(18)F]FMISO-PET imaging of 30 lesions resulted in a SUVmax median value of 2.3 and a TMR median value of 1.3. Local control rates with radiotherapy (20-month median follow-up duration) were significantly lower in the tumor group with high uptake of [(18)F]FMISO compared to the tumor group with low uptake of [(18)F]FMISO using either SUVmax or TMR as the hypoxic indicator (P = 0.02 and 0.04, respectively). DSS rate with radiotherapy or operation (21-month median follow-up duration) was significantly lower in the patient group with high uptake of [(18)F]FMISO compared to the patient group with low uptake of [(18)F]FMISO defined by SUVmax (P = 0.04), but was not by TMR (P = 0.57). CONCLUSIONS Radiotherapy outcome and survival prognosis (radiotherapy or operation) in HNSCC may be predicted by carrying out [(18)F]FMISO PET before treatment.
Collapse
Affiliation(s)
- Masahiro Kikuchi
- Department of Otolaryngology, Head and Neck Surgery, Kobe City Medical Center General Hospital, 4-6 Minatojima-Nakamachi, Chuo-ku, Kobe 650-0046, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Rodríguez-Enríquez S, Carreño-Fuentes L, Gallardo-Pérez JC, Saavedra E, Quezada H, Vega A, Marín-Hernández A, Olín-Sandoval V, Torres-Márquez ME, Moreno-Sánchez R. Oxidative phosphorylation is impaired by prolonged hypoxia in breast and possibly in cervix carcinoma. Int J Biochem Cell Biol 2010; 42:1744-51. [DOI: 10.1016/j.biocel.2010.07.010] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 06/18/2010] [Accepted: 07/12/2010] [Indexed: 10/19/2022]
|
17
|
Koch CJ, Shuman AL, Jenkins WT, Kachur AV, Karp JS, Freifelder R, Dolbier WR, Evans SM. The radiation response of cells from 9L gliosarcoma tumours is correlated with [F18]-EF5 uptake. Int J Radiat Biol 2010; 85:1137-47. [PMID: 19995239 DOI: 10.3109/09553000903242172] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Tumour hypoxia affects cancer biology and therapy-resistance in both animals and humans. The purpose of this study was to determine whether EF5 ([2-(2-nitro-1-H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)-acetamide]) binding and/or radioactive drug uptake correlated with single-dose radiation response in 9L gliosarcoma tumours. MATERIALS AND METHODS Twenty-two 9L tumours were grown in male Fischer rats. Rats were administered low specific activity (18)F-EF5 and their tumours irradiated and assessed for cell survival and hypoxia. Hypoxia assays included EF5 binding measured by antibodies against bound-drug adducts and gamma counts of (18)F-EF5 tumour uptake compared with uptake by normal muscle and blood. These assays were compared with cellular radiation response (in vivo to in vitro assay). In six cases, uptake of tumour versus muscle was also assayed using images from a PET (positron emission tomography) camera (PENN G-PET). RESULTS The intertumoural variation in radiation response of 9L tumour-cells was significantly correlated with uptake of (18)F-labelled EF5 (i.e., including both bound and non-bound drug) using either tumour to muscle or tumour to blood gamma count ratios. In the tumours where imaging was performed, there was a significant correlation between the image analysis and gamma count analysis. Intertumoural variation in cellular radiation response of the same 22 tumours was also correlated with mean flow cytometry signal due to EF5 binding. CONCLUSION To our knowledge, this is the first animal model/drug combination demonstrating a correlation of radioresponse for tumour-cells from individual tumours with drug metabolism using either immunohistochemical or non-invasive techniques.
Collapse
Affiliation(s)
- Cameron J Koch
- Departments of Radiation Oncology, University of Pennsylvania, 195 John Morgan Bldg., 37th St & Hamilton Walk, Philadelphia, PA, 19104-6072, USA.
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Cytotoxicity of Paclitaxel Incorporated in PLGA Nanoparticles on Hypoxic Human Tumor Cells. Pharm Res 2009; 26:1776-84. [DOI: 10.1007/s11095-009-9889-z] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Accepted: 04/02/2009] [Indexed: 10/20/2022]
|
19
|
Shuhendler AJ, O'Brien PJ, Rauth AM, Wu XY. On the synergistic effect of doxorubicin and mitomycin C against breast cancer cells. ACTA ACUST UNITED AC 2008; 22:201-33. [PMID: 18447000 DOI: 10.1515/dmdi.2007.22.4.201] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The combination of doxorubicin and mitomycin C has been shown previously to result in supra-additive tumor cell killing in vitro in both murine and human breast cancer cells and in vivo against murine breast cancer cells. Median effect analysis was used to determine the significance and degree of interaction. The origin of this synergy was sought by evaluating the contribution of membrane efflux pump modulation, formaldehyde production, reactive oxygen species, DNA cross-linking, and DNA double-strand breaks to this effect. The interaction of mitomycin C and doxorubicin in vitro was found to be a true synergy whose mechanism was efflux pump-independent. DNA cross-links were only found to increase additively with co-administration of the drugs; however, a supra-additive increase in DNA double-strand breaks was observed. The results suggest that poisoning of topoisomerase IIalpha by doxorubicin may interact with drug-induced DNA cross-links to enhance the formation of DNA double-strand breaks. This interaction, together with glutathione depletion and mitomycin C-derived formaldehyde, may be the underlying mechanism(s) of the synergy observed between mitomycin C and doxorubicin.
Collapse
Affiliation(s)
- Adam J Shuhendler
- Leslie Dan Faculty of Pharmacy, University of Toronto, Ontario, Canada
| | | | | | | |
Collapse
|
20
|
Koch CJ. Importance of antibody concentration in the assessment of cellular hypoxia by flow cytometry: EF5 and pimonidazole. Radiat Res 2008; 169:677-88. [PMID: 18494550 DOI: 10.1667/rr1305.1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Accepted: 02/06/2008] [Indexed: 11/03/2022]
Abstract
The binding kinetics of the hypoxia marker EF5 can be quantified by uptake of (14)C-labeled drug or calibrated flow cytometry using antibodies specific for drug adducts. Maximum EF5 binding is cell-line dependent and varies directly with drug exposure (area under the curve; concentration integrated over time) but inversely with pO(2) from 0 to >100 mmHg. For pimonidazole, binding is reported to be independent of the cell line and drug AUC, being zero above 10 mmHg, with an easily discriminated increase at lower pO(2). The basis for these kinetic differences is unknown, but the main experimental variable distinguishing the two marker techniques is antibody concentration ([Ab] - pimonidazole << EF5). In this study, EF5 and pimonidazole binding kinetics were compared as a function of pO(2) and antibody concentration in cells of two rat (9L and R3230) and two human (HT1080 and SiHa) cancer cell lines. For both markers, binding varied directly with AUC at all pO(2). The dynamic range of observed binding (maximum change from 0 to 76 mmHg oxygen) decreased with antibody concentration. The pO(2) dependence of binding for pimonidazole, but not EF5, varied dramatically with antibody concentration. Thus the data presented herein do not support the reported binding kinetics of pimonidazole. In particular, it is shown that the common use of antibody concentrations much lower than antigen concentrations can lead to unreliable estimations of adduct level and hence pO(2).
Collapse
Affiliation(s)
- Cameron J Koch
- Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104-6072, USA.
| |
Collapse
|
21
|
Hicks KO, Myint H, Patterson AV, Pruijn FB, Siim BG, Patel K, Wilson WR. Oxygen Dependence and Extravascular Transport of Hypoxia-Activated Prodrugs: Comparison of the Dinitrobenzamide Mustard PR-104A and Tirapazamine. Int J Radiat Oncol Biol Phys 2007; 69:560-71. [PMID: 17869669 DOI: 10.1016/j.ijrobp.2007.05.049] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2007] [Revised: 05/28/2007] [Accepted: 05/29/2007] [Indexed: 10/22/2022]
Abstract
PURPOSE To compare oxygen dependence and tissue transport properties of a new hypoxia-activated prodrug, PR-104A, with tirapazamine, and to evaluate the implications for antitumor activity when combined with radiotherapy. METHODS AND MATERIALS Oxygen dependence of cytotoxicity was measured by clonogenic assay in SiHa cell suspensions. Tissue transport parameters were determined using SiHa multicellular layers. Spatially resolved pharmacokinetic (PK) and pharmacodynamic (PD) models were developed to predict cell killing in SiHa tumors and tested by clonogenic assay 18 h after treatment with the corresponding phosphate ester, PR-104. RESULTS The K-value (oxygen concentration to halve cytotoxic potency) of PR-104A was 0.126 +/- 0.021 microM (10-fold lower than tirapazamine at 1.30 +/- 0.28 microM). The diffusion coefficient of PR-104A in multicellular layers (4.42 +/- 0.15 x 10(-7) cm2 s(-1)) was lower than that of tirapazamine (1.30 +/- 0.05 x 10(-6) cm2 s(-1)) but PK modeling predicted better penetration to hypoxic cells in tumors because of its slower metabolism. The tirapazamine PK/PD model successfully predicted the measured activity in combination with single-dose radiation against SiHa tumors, and the PR-104A model underpredicted the activity, which was greater for PR-104 than for tirapazamine (at equivalent host toxicity) both with radiation and as a single agent. CONCLUSION PR-104/PR-104A has different PK/PD properties from tirapazamine and superior activity with single-dose radiotherapy against SiHa xenografts. We have inferred that PR-104A is better able to kill cells at intermediate partial pressure of oxygen in tumors than implied by the PK/PD model, most likely because of a bystander effect resulting from diffusion of its activated metabolites from severely hypoxic zones.
Collapse
Affiliation(s)
- Kevin O Hicks
- Auckland Cancer Society Research Centre, University of Auckland School of Medical Sciences, Auckland, New Zealand.
| | | | | | | | | | | | | |
Collapse
|
22
|
Affiliation(s)
- Naz Chaudary
- Applied Molecular Oncology, Ontario Cancer Institute/Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada
| | | |
Collapse
|
23
|
Rofstad EK, Galappathi K, Mathiesen B, Ruud EBM. Fluctuating and Diffusion-Limited Hypoxia in Hypoxia-Induced Metastasis. Clin Cancer Res 2007; 13:1971-8. [PMID: 17360973 DOI: 10.1158/1078-0432.ccr-06-1967] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Most tumors develop regions with hypoxic cells during growth, owing to permanent limitations in oxygen diffusion (chronic or diffusion-limited hypoxia) and/or transient limitations in blood perfusion (acute or fluctuating hypoxia). The aim of this study was to investigate the relative significance of chronic and acute hypoxia in the development of metastatic disease. EXPERIMENTAL DESIGN D-12 and R-18 human melanoma xenografts were used as models of human cancer. D-12 tumors metastasize to the lungs, whereas R-18 tumors develop lymph node metastases. Fraction of radiobiologically hypoxic cells (HF(Rad)) was measured in individual primary tumors by using a radiobiological assay based on the paired survival curve method. Fraction of immunohistochemically hypoxic cells (HF(Imm)) was assessed in the same tumors by using a pimonidazole-based immunohistochemical assay optimized with respect to achieving selective staining of chronically hypoxic cells. HF(Imm) and the difference between HF(Rad) and HF(Imm), HF(Rad) - HF(Imm), were verified to be adequate variables for fraction of chronically hypoxic cells and fraction of acutely hypoxic cells, respectively. RESULTS Chronic as well as acute hypoxia were found to promote spontaneous metastasis of D-12 and R-18 tumors. Acute hypoxia influenced metastasis to a greater extent than chronic hypoxia, partly because the fraction of acutely hypoxic cells was larger than the fraction of chronically hypoxic cells in most tumors and partly because acutely hypoxic cells showed a higher metastatic potential than chronically hypoxic cells. CONCLUSIONS It may be beneficial to focus on fluctuating hypoxia rather than diffusion-limited hypoxia when searching for hypoxia-related prognostic variables and predictive assays.
Collapse
Affiliation(s)
- Einar K Rofstad
- Group of Radiation Biology and Tumor Physiology, Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway.
| | | | | | | |
Collapse
|
24
|
Biaglow JE, Ayene IS, Tuttle SW, Koch CJ, Donahue J, Mieyal JJ. Role of vicinal protein thiols in radiation and cytotoxic responses. Radiat Res 2006; 165:307-17. [PMID: 16494519 DOI: 10.1667/rr3505.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Glutathione (GSH) and more recently protein thiols (P-SH) have been found to play a major role in cellular radiation response. However, the effects of protein vicinal thiols, which are important for the functions of several major enzymes, on cellular responses to radiation have not been clearly delineated. Here we investigated the effects of depleting GSH and protein vicinal thiols (HS-P-SH) and P-SH on cell toxicity and radiation response. We used hydroxyethyldisulfide (HEDS, beta-mercaptoethanol-disulfide) alone and in combination with phenylarsine oxide (PAO) to alter P-SH, HS-P-SH and GSH. HEDS, a direct substrate for thioredoxin reductase and an indirect substrate for glutaredoxin (thioltransferase), did not alter protein vicinal thiols in cells. However, PAO, which specifically forms a covalent adduct with vicinal thiols, blocked bioreduction of HEDS; there was a concomitant and yet unexplained decrease in K1 cell GSH in the presence of HEDS and PAO. G6PD+ (K1) and G6PD- (E89) cells treated with L-buthionine sulfoximine (L-BSO) for 72 h to deplete GSH followed by PAO showed an increased cytotoxic response. However, the surviving E89 cells showed a 10,000-fold greater radiation lethality than the K1 cells. The effects of rapid depletion of GSH by a combination of L-BSO and dimethyfumarate (DMF), a glutathione-S-transferase substrate, were also investigated. Under these conditions, PAO radiosensitized the E89 cells more than 1000-fold over the K1 cells. The potential mechanisms for the altered response may be related to the inhibition of thioredoxin reductase and glutaredoxin. Both are key enzymes involved in DNA synthesis, protein homeostasis and cell survival. With GSH removed, vicinal thiols appear to play a critical role in determining cell survival and radiosensitivity. Decreasing P-SH and removing GSH and vicinal thiols is extremely toxic to K1 and E89 cells. We conclude that radiation sensitivity and cell survival are dependent on vicinal thiol and GSH. In the former and latter cases, the protein thiols are also important.
Collapse
Affiliation(s)
- John E Biaglow
- Department of Biochemistry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
| | | | | | | | | | | |
Collapse
|
25
|
Hedley DW, Nicklee T, Moreno-Merlo F, Pintilie M, Fyles A, Milosevic M, Hill RP. Relations between non–protein sulfydryl levels in the nucleus and cytoplasm, tumor oxygenation, and clinical outcome of patients with uterine cervical carcinoma. Int J Radiat Oncol Biol Phys 2005; 61:137-44. [PMID: 15629604 DOI: 10.1016/j.ijrobp.2004.02.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Revised: 01/01/2004] [Accepted: 02/06/2004] [Indexed: 11/25/2022]
Abstract
PURPOSE The non-protein sulfydryls (NPSH) glutathione and cysteine are able to effect chemical repair of radiation-induced DNA damage, particularly under hypoxic conditions, and are implicated in radioresistance. The levels of NPSH in the nucleus are predicted to be more important than those in cytoplasm. We, therefore, investigated the relation between nuclear NPSH and the clinical outcome of radical radiotherapy (RT). METHODS AND MATERIALS A fluorescence image analysis technique to measure nuclear NPSH was developed, based on the SH-reactive probe 1(4-chloromercuryphenyl-azo-2-naphthol) and the DNA dye 4,6-diamidino-2-phenylindole. This was used to measure nuclear and tissue NPSH levels in biopsies obtained from 58 patients with locally advanced uterine cervical carcinoma, treated with radical RT. RESULTS An approximately twofold range in the nuclear and tissue NPSH levels between individual tumors was found, although the intratumoral heterogeneity was much smaller. Nuclear and tissue NPSH values correlated closely in all cases. No statistically significant associations were noted between NPSH levels and tumor size, stage, or tumor hypoxia as determined at the time of biopsy using an Eppendorf po(2) probe. The response to RT and patient survival did not correlate with tumor NPSH. CONCLUSION These results did not support the existence of an independently regulated nuclear pool of NPSH and showed that tissue and nuclear NPSH are not predictive of the outcome of patients with locally advanced cervical carcinomas treated with RT.
Collapse
Affiliation(s)
- David W Hedley
- Department of Medical Oncology and Hematology, Toronto, ON, Canada.
| | | | | | | | | | | | | |
Collapse
|
26
|
Koch CJ. In regard to Vordermark et al. (Int J Radiat Oncol Biol Phys 2004;58:1242–1250). Int J Radiat Oncol Biol Phys 2004; 60:1003-4; author reply 1004-5. [PMID: 15465220 DOI: 10.1016/j.ijrobp.2004.07.673] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
27
|
Hicks KO, Siim BG, Pruijn FB, Wilson WR. Oxygen dependence of the metabolic activation and cytotoxicity of tirapazamine: implications for extravascular transport and activity in tumors. Radiat Res 2004; 161:656-66. [PMID: 15161354 DOI: 10.1667/rr3178] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The hypoxic cytotoxin tirapazamine (TPZ) is currently in phase III clinical trial and appears to have clinical activity. One hypothesis as to why TPZ has been used more successfully in the clinic than most other bioreductive drugs is that its unusual O(2) dependence allows killing of radioresistant cells at "intermediate" O(2) concentrations. We have determined the O(2) dependence of the metabolism of TPZ to its reduction product SR 4317, and its cytotoxicity, in stirred suspensions of HT29 colon carcinoma cells while monitoring O(2) in solution with an Oxylite trade mark probe. The O(2) dependence of the cytotoxicity of TPZ is entirely accounted for by its inhibition of the metabolism of TPZ, with a K(O(2)) value (O(2) concentration for 50% inhibition) of 1.21 +/- 0.09 (SEM) microM. We used this experimental O(2) dependence to extend a recent (Hicks et al., Cancer Res. 63, 5970-5977, 2003) pharmacokinetic/pharmacodynamic model for the cytotoxicity of TPZ in anoxic HT29 multicellular layers to model cell killing in tumors. The model indicates that the O(2) dependence of killing by TPZ complements that of radiation well during fractionated radiotherapy. It predicts that lowering K(O(2)) would decrease killing in radioresistant cells at intermediate O(2) concentrations, while higher K(O(2)) values would exacerbate metabolic consumption of TPZ and thus further impede its penetration into hypoxic regions. Raising K(O(2)) would also increase metabolic activation at physiological O(2) concentrations, thereby compromising hypoxic selectivity. We conclude that the K(O(2)) value of TPZ is indeed close to the optimum for a bioreductive drug of this class (i.e. one that kills only cells in which it is reduced).
Collapse
Affiliation(s)
- Kevin O Hicks
- Auckland Cancer Society Research Centre, The University of Auckland, Auckland, New Zealand.
| | | | | | | |
Collapse
|
28
|
Evans SM, Judy KD, Dunphy I, Jenkins WT, Nelson PT, Collins R, Wileyto EP, Jenkins K, Hahn SM, Stevens CW, Judkins AR, Phillips P, Geoerger B, Koch CJ. Comparative Measurements of Hypoxia in Human Brain Tumors Using Needle Electrodes and EF5 Binding. Cancer Res 2004; 64:1886-92. [PMID: 14996753 DOI: 10.1158/0008-5472.can-03-2424] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypoxia is known to be an important prognostic marker in many human cancers. We report the use of two oxygen measurement techniques in human brain tumors and compare these data with semiquantitative histological end points. Oxygenation was measured using the Eppendorf needle electrode and/or EF5 binding in 28 brain tumors. These data were compared with necrosis, mitosis, and endothelial proliferation. In some tumors, absolute EF5 binding was converted to tissue pO(2) based on in vitro calibrations. Eppendorf electrode readings could not be used to identify WHO grade 1/2 versus WHO grade 3/4 tumors, they could not differentiate grade 3 versus grade 4 glial-derived neoplasms, nor did they correlate with necrosis or endothelial proliferation scores. EF5 binding increased as the tumor grade increased and was significantly associated with necrosis and endothelial proliferation. There was no statistically significant correlation between the two hypoxia detection techniques, although both methods indicated similar absolute ranges of tissue pO(2). There was substantial inter- and intratumoral heterogeneity of EF5 binding in WHO grade 4 glial neoplasms. The majority of cells in glial-derived tumor had levels of hypoxia that were mild to moderate (defined herein as 10% to 0.5% pO(2)) rather than severe (defined as approximately 0.1% pO(2)). Immunohistochemical detection of EF5 binding tracks histological parameters in adult brain tumors, with increased binding associated with increasing necrosis and endothelial proliferation. The proportion of moderately to severely hypoxic cells is relatively low, even in the high-grade tumors. Human brain tumors are dominated by oxic to moderately hypoxic cells.
Collapse
Affiliation(s)
- Sydney M Evans
- School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Abstract
Low tissue oxygen concentration has been shown to be important in the response of human tumors to radiation therapy, chemotherapy and other treatment modalities. Hypoxia is also known to be a prognostic indicator, as hypoxic human tumors are more biologically aggressive and are more likely to recur locally and metastasize. Herein, we discuss and summarize the various methods under investigation to directly or indirectly measure tissue oxygen in vivo. Secondly, we consider the advantages and disadvantages of each of these techniques. These considerations are made in light of our specific hypotheses that hypoxia should be measured as a continuum, not a binary measurement and that moderate, not severe hypoxia is of great biological consequence.
Collapse
Affiliation(s)
- Sydney M Evans
- School of Medicine, Department of Radiation Oncology, 195 John Morgan Building, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | | |
Collapse
|