Evidence for acutely hypoxic cells in mouse tumours, and a possible mechanism of reoxygenation

Jm, Brown

doi:10.1259/0007-1285-52-620-650

Cited by 478 publications

(227 citation statements)

References 7 publications

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“…Such transiently hypoxic cells would not be exposed to the drug in a hypoxic environment for long enough to allow full expression of the anaerobic metabolism and hence cytotoxicity. However, all efforts to overcome the problem of a short half life (by nephrectomy to prevent excretion, by repeated injections of drug or by continuous infusion) have proved incapable of demonstrating a much larger cytotoxic effect in mice (Brown et al, 1979;Pedersen et al, 1979). This is consistent with deductions of minimal cytotoxicity from the scanty human data that are available, where the longer half life in man (10-18 h) should permit the full cytotoxic effect (Denekamp & McNally, 1978).…”

Section: Resultsmentioning

confidence: 67%

“…Cells which are acutely hypoxic only for the duration of irradiation (e.g. as a result of periodic opening and closing of blood vessels) may be more important to the radiation response than cells which are chronically hypoxic at a maximum distance from the capillaries (Yamaura & Matsuzawa, 1979;Brown, 1979). Such transiently hypoxic cells would not be exposed to the drug in a hypoxic environment for long enough to allow full expression of the anaerobic metabolism and hence cytotoxicity.…”

Section: Resultsmentioning

confidence: 99%

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Is tumour radiosensitization by misonidazole a general phenomenon?

Denekamp¹,

Hirst²,

Stewart³

et al. 1980

Br J Cancer

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Summary.-The response of 14 mouse tumour sub-lines to the radiosensitizing action of a large single dose of misonidazole (MISO) has been assessed by regrowth delay. In 13 of these, significant enhancement of radiation effect occurred under ambient conditions, indicating sensitization of naturally hypoxic cells. The enhancement observed (SER') varied with the radiation dose, as would be predicted for a mixed oxic/hypoxic cell population. The maximum SER' in these 13 tumours did not depend on histology or regrowth rate.The 14th tumour, a slow-growing sarcoma, was not sensitized under ambient conditions, but showed marked sensitization when clamped to produce acutely hypoxic cells. This is consistent with no hypoxic cells occurring naturally in a sarcoma with a slow rate of growth. Faster-growing variants of this tumour showed radiosensitization under ambient conditions.The slow-growing carcinoma, RH, however, appears to contain hypoxic cells and did show sensitization. The cytotoxic action of MIS0 was compared with the radiosensitization by administering it after irradiation in 8 of the tumour lines. In 2 tumours no cytotoxicity was observed. In the rest cytotoxicity was significant, but much smaller than the sensitization observed when MISO was administered before irradiation.These regrowth-delay data have been used to calculate hypoxic fractions in 3 ways.Estimates of hypoxic fraction ranged from <0-1% in the slow sarcoma to >30% in several tumours. There is considerable variation in the estimate, according to the technique used.

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Section: Resultsmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Is tumour radiosensitization by misonidazole a general phenomenon?

Denekamp¹,

Hirst²,

Stewart³

et al. 1980

Br J Cancer

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show abstract

“…Diffusion limited hypoxia is a characteristic of solid tumours which has been appreciated for many years (Thomlinson and Gray, 1955). However, it is now recognized that hypoxic cells can also arise from perfusion driven changes in oxygen supply, resulting in rapid and reversible changes in oxygenation (Brown, 1979;Chaplin et al, 1987;Kimura et al, 1996). Hypoxic cells are resistant to radiation (Thomlinson and Gray, 1955) and to some chemotherapeutic agents (Teicher et al, 1981;Hoeckel et al, 1999) and are generally perceived as a hindrance to cancer therapy.…”

mentioning

confidence: 99%

Gene delivery to hypoxic cells in vitro

et al. 2000

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Summary Hypoxia in solid tumours has been correlated with poor prognosis and resistance to radiation and chemotherapy. Hypoxia is also a strong stimulus for gene expression. We previously proposed a gene therapy approach which exploits the presence of severe hypoxia in tumours for the induction of therapeutic genes. Hypoxic cells are known to have a reduced metabolic rate, transcription and translation. These facts may prevent gene transfer and therefore warranted further investigation. In this paper the feasibility of gene delivery in vitro under tumour conditions was demonstrated. DNA was delivered in vitro using a peptide-mediated non-viral system. Across a range of oxygen tensions and mammalian cell lines (including human tumour and endothelial cells) it was shown that hypoxic cells could be transfected. Transfection efficiencies varied depending on the level of hypoxia, cell characteristics and gene promoters used. An in vitro model of hypoxia/reoxygenation, designed to mimic the variable nature of tumour hypoxia, showed that hypoxic preconditioning and reoxygenation alone did not reduce transfection efficiency significantly; only chronic anoxia reduced transfection. The fact that neither intermediate hypoxia nor intermittent anoxia significantly reduced transfection is promising for future hypoxia-targeted gene therapy strategies. 662-667 © 2000 Cancer Research Campaign doi: 10.1054/ bjoc.2000.1318, available online at http://www.idealibrary.com on List of abbreviations: HIF-1, hypoxia inducible factor 1; CMV, cytomegalovirus; SV40, simian virus 40; AnO 2 , anoxia; GFP, green fluorescent protein; FACS, fluorescent activated cell sorting Transfection efficiencies of two commonly used marker genes and viral promoters were recorded in a range of cell lines under different oxygenation conditions. A simple in vitro model of hypoxia/reoxygenation was used to mimic the variable nature of tumour hypoxia. MATERIALS AND METHODS Cell lines and growth mediaThe human bladder carcinoma cell line T24 (European Collection of Cell Cultures; Bubenik et al, 1973;Dirks et al, 1999), the immortalized human microvascular endothelial cell line HMEC-1 (Ades et al, 1992), human squamous carcinoma cell line of the head and neck FaDu (Rangan, 1972; American Type Culture Collection), the mouse hepatoma cell line Hepa-1 wild type (clone Hepa-1c1c7) and its derivative Hepa c4 (HIF-1β mutant; Hankinson, 1979) were utilised. Only cells tested negative for mycoplasma were used in the experiments, since it had been shown that mycoplasma interfered with transfection, especially under hypoxia (results not shown). All cells were maintained in Dulbecco's MEM (DMEM, Life Technologies, UK) with 10% fetal calf serum and L-glutamine in a 5% CO 2 humidified incubator at 37°C.Cell proliferation was monitored by cell counting using a haemocytometer and trypan blue (0.2% final concentration, Sigma) to distinguish live and dead cells. Hypoxic conditionsCells were plated 16-24 h prior to the experiment in oxygen impermeable dishes (Permanox, Nunc, UK...

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“…Two types of hypoxia have been recognized: chronic hypoxia, arising from limitations in oxygen diffusion, and acute hypoxia, resulting from transient stoppages in microregional blood flow (Stone et al, 1993;Horsman, 1995). Reoxygenation of hypoxic cells occurs during unperturbed tumour growth as a result of reopening of temporarily closed vessels and during therapy as a result of therapy-induced tumour cell inactivation (Kallman, 1972;Brown, 1979;Chaplin et al, 1987). Hypoxia followed by reoxygenation might promote the malignant progression of tumours (Hill, 1990).…”

mentioning

confidence: 99%

Hypoxia-induced angiogenesis and vascular endothelial growth factor secretion in human melanoma

Rofstad

Danielsen²

1998

Br J Cancer

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Summary Tumour cells exposed to hypoxia in vitro can show increased expression of several selected genes, including the gene encoding the vascular endothelial growth factor (VEGF), suggesting that hypoxia followed by reoxygenation might promote the malignant progression of tumours. An in vitro/in vivo study was conducted to investigate whether hypoxia can increase the angiogenic potential of tumour cells through increased VEGF secretion. Four human melanoma cell lines (A-07, D-12, R-18, U-25) were included in the study. Cell cultures were exposed to hypoxia (oxygen concentration <10 p.p.m.) in vitro using the steel chamber method. Rate of VEGF secretion was measured in vitro in aerobic and hypoxic cell cultures by ELISA. Angiogenesis was assessed in vivo using the intradermal angiogenesis assay. Aliquots of cells harvested from aerobic cultures or cultures exposed to hypoxia for 24 h were inoculated intradermally in the flanks of adult female BALB/cnu/nu mice. Tumours developed and angiogenesis was quantified by scoring the number of capillaries in the dermis oriented towards the tumours. The number of tumour-oriented capillaries did not differ significantly between tumours from hypoxic and aerobic cultures for A-07 and U-25, whereas tumours from hypoxic cultures showed a larger number of tumour-oriented capillaries than tumours from aerobic cultures for D-1 2 and R-1 8. The VEGF secretion under aerobic conditions and the absolute increase in VEGF secretion induced by hypoxia were lower for D-12 and R-18 than for A-07 and U-25, whereas the relative increase in VEGF secretion induced by hypoxia was higher for D-12 and R-18 than for A-07 and U-25. VEGF is not a limiting factor in the angiogenesis of some tumours under normoxic conditions. Hypoxia can increase the angiogenic potential of tumour cells by increasing the secretion of VEGF, but only of tumour cells showing low VEGF secretion under normoxia. Transient hypoxia might promote the malignant progression of tumours by temporarily increasing the angiogenic potential of tumour cells showing low VEGF expression under normoxic conditions. Keywords: angiogenesis; hypoxia; melanoma; vascularization; VEGF Many malignant tumours develop regions of hypoxic cells during growth (Coleman, 1988;Vaupel et al, 1989;Brown and Giaccia, 1994). Two types of hypoxia have been recognized: chronic hypoxia, arising from limitations in oxygen diffusion, and acute hypoxia, resulting from transient stoppages in microregional blood flow (Stone et al, 1993;Horsman, 1995). Reoxygenation of hypoxic cells occurs during unperturbed tumour growth as a result of reopening of temporarily closed vessels and during therapy as a result of therapy-induced tumour cell inactivation (Kallman, 1972;Brown, 1979;Chaplin et al, 1987). Hypoxia followed by reoxygenation might promote the malignant progression of tumours (Hill, 1990). Thus, tumour cells exposed to hypoxia in vitro can show increased expression of several selected genes, including genes encoding cell cycle-regulatory proteins, haematopoietic...

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Evidence for acutely hypoxic cells in mouse tumours, and a possible mechanism of reoxygenation

Cited by 478 publications

References 7 publications

Is tumour radiosensitization by misonidazole a general phenomenon?

Is tumour radiosensitization by misonidazole a general phenomenon?

Gene delivery to hypoxic cells in vitro

Hypoxia-induced angiogenesis and vascular endothelial growth factor secretion in human melanoma

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