Radiosensitization of human glioma cells in vitro and in vivo with acyclovir and mutant HSV-TK75 expressed from adenovirus

Rosenberg, Elizabeth; Hawkins, William; Holmes, Matthew; Amir, Cyrus; Schmidt‐Ullrich, Rupert; Lin, Peck Sun; Valerie, Kristoffer

doi:10.1016/s0360-3016(01)02754-7

Cited by 18 publications

(10 citation statements)

References 18 publications

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“…Such studies have used both adenoviral and herpes simplex viral vectors. [11][12][13][14][15][16][17][18][19][20] The virus-prodrug systems that have been used have Nitroreductase/CB1954 plus radiotherapy CL White et al focussed largely on HSVtk and ganciclovir and/or E. coli cytosine deaminase/uracil phosphoribosyltransferase and 5-fluorocytosine. These systems have shown significant advantages in terms of both in vitro and in vivo cell killing.…”

Section: Discussionmentioning

confidence: 99%

Escherichia coli nitroreductase plus CB1954 enhances the effect of radiotherapy in vitro and in vivo

et al. 2007

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Escherichia coli nitroreductase (NTR) converts the prodrug CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide) into a bifunctional alkylating agent that causes DNA crosslinks. In this study, the ability of NTR to enhance the combined effects of CB1954 and radiation has been tested in vitro and in vivo. Stably transduced ovarian cancer cells (SKOV3-NTR) that are sensitive to CB1954 (IC 50 ¼ 0.35 mM) demonstrated enhanced cytotoxicity when treated with CB1954 and single-fraction irradiation. The NTR-CB1954 system mediated a bystander effect in combination with radiation on transfer of conditioned medium from SKOV3-NTR, but not SKOV3, cells to SW480 target cells. The ability of CB1954 to enhance radiationinduced cytotoxicity in SKOV3-NTR (but not SKOV3) cells was also demonstrated by fluorescence-activated cell sorting (FACS) with dual staining for propidium iodide/fluorescein diacetate, 4 0 ,6-diamidino-2-phenylindole dichloride staining of apoptotic cells and measurement of double-stranded DNA breaks by FACS and confocal microscopy for gH2AX foci. Adenoviral delivery of NTR, under constitutive cytomegalovirus or tissue-specific CTP1 promoters, increased the in vitro cytotoxicity of CB1954 plus radiation in MTT and clonogenic assays. Finally, adenoviral delivery of NTR plus CB1954 enhanced the effect of fractionated radiotherapy (12 Gy in four fractions) in SW480 xenograft tumours in nude mice.

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Section: Discussionmentioning

confidence: 99%

Escherichia coli nitroreductase plus CB1954 enhances the effect of radiotherapy in vitro and in vivo

et al. 2007

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“…Clones were screened for increased ERK1/2 phosphorylation in response to 4-hydroxytamoxifen by Western blotting. Cells were irradiated with UV-C (254 nm) and IR (17,18). Inhibitors were added to the cell culture medium to the indicated final concentrations 1 h before treatment and left in the medium throughout the experiment.…”

Section: Methodsmentioning

confidence: 99%

Extracellular Signal-Related Kinase Positively Regulates Ataxia Telangiectasia Mutated, Homologous Recombination Repair, and the DNA Damage Response

et al. 2007

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The accurate joining of DNA double-strand breaks by homologous recombination repair (HRR) is critical to the long-term survival of the cell. The three major mitogenactivated protein (MAP) kinase (MAPK) signaling pathways, extracellular signal-regulated kinase (ERK), p38, and c-Jun-NH 2 -kinase (JNK), regulate cell growth, survival, and apoptosis. To determine the role of MAPK signaling in HRR, we used a human in vivo I-SceI-based repair system. First, we verified that this repair platform is amenable to pharmacologic manipulation and show that the ataxia telangiectasia mutated (ATM) kinase is critical for HRR. The ATM-specific inhibitor KU-55933 compromised HRR up to 90% in growth-arrested cells, whereas this effect was less pronounced in cycling cells. Then, using well-characterized MAPK small-molecule inhibitors, we show that ERK1/2 and JNK signaling are important positive regulators of HRR in growth-arrested cells. On the other hand, inhibition of the p38 MAPK pathway generated an almost 2-fold stimulation of HRR. When ERK1/2 signaling was stimulated by oncogenic RAF-1, an f2-fold increase in HRR was observed. KU-55933 partly blocked radiation-induced ERK1/2 phosphorylation, suggesting that ATM regulates ERK1/2 signaling. Furthermore, inhibition of MAP/ERK kinase (MEK)/ERK signaling resulted in severely reduced levels of phosphorylated (S1981) ATM foci but not ;-H2AX foci, and suppressed ATM phosphorylation levels >85% throughout the cell cycle. Collectively, these results show that MAPK signaling positively and negatively regulates HRR in human cells. More specifically, ATM-dependent signaling through the RAF/MEK/ ERK pathway is critical for efficient HRR and for radiationinduced ATM activation, suggestive of a regulatory feedback loop between ERK and ATM. [Cancer Res 2007;67(3):1046-53]

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“…Cell Culture and Adenovirus Treatment-Human malignant glioma U87 (p53 ϩ ) cells, and the M059K (DNA-PK cs ϩ ), M059J (DNA-PK cs Ϫ ) cell pair (38,39) were cultured in ␣-minimal essential medium (Invitrogen) supplemented with 20% fetal bovine serum (Irvine Scientific, Santa Ana, CA) and penicillin/streptomycin as described (40). Cells were transfected with the DR-GFP plasmid (41) using LipofectAMINE Plus (Invitrogen).…”

Section: Methodsmentioning

confidence: 99%

Double Strand Break Repair by Homologous Recombination Is Regulated by Cell Cycle-independent Signaling via ATM in Human Glioma Cells

Golding

Rosenberg

Khalil

et al. 2004

Journal of Biological Chemistry

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115

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To investigate double strand break (DSB) repair and signaling in human glioma cells, we stably transfected human U87 (ATM ؉ , p53 ؉ ) glioma cells with a plasmid having a single I-SceI site within an inactive green fluorescent protein (GFP) expression cassette, allowing for the detection of homologous recombination repair (HRR) by GFP expression. HRR and nonhomologous end joining (NHEJ) were also determined by PCR. DSB repair was first detected at 12 h postinfection with an adenovirus expressing I-SceI with repair reaching plateau levels between 24 and 48 h. Within this time frame, NHEJ predominated over HRR in the range of 3-50-fold. To assess the involvement of ATM in DSB repair, we first examined whether ATM was associated with the DSB. Chromatin immunoprecipitation showed that ATM was present at the site of the DSB as early as 18 h postinfection. In cells treated with caffeine, an inhibitor of ATM, HRR was reduced, whereas NHEJ was not. In support of this finding, GFP flow cytometry demonstrated that caffeine reduced HRR by 90% under conditions when ATM kinase activity was inhibited. Dominant-negative ATM expressed from adenovirus inhibited HRR by 45%, also having little to no effect on NHEJ. Furthermore, HRR was inhibited by caffeine in serum-starved cells arrested in G 0 /G 1 , suggesting that ATM is also important for HRR outside of the S and G 2 cell cycle phases. Altogether, these results demonstrate that HRR contributes substantially to DSB repair in human glioma cells, and, importantly, ATM plays a critical role in regulating HRR but not NHEJ throughout the cell cycle.

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Radiosensitization of human glioma cells in vitro and in vivo with acyclovir and mutant HSV-TK75 expressed from adenovirus

Cited by 18 publications

References 18 publications

Escherichia coli nitroreductase plus CB1954 enhances the effect of radiotherapy in vitro and in vivo

Escherichia coli nitroreductase plus CB1954 enhances the effect of radiotherapy in vitro and in vivo

Extracellular Signal-Related Kinase Positively Regulates Ataxia Telangiectasia Mutated, Homologous Recombination Repair, and the DNA Damage Response

Double Strand Break Repair by Homologous Recombination Is Regulated by Cell Cycle-independent Signaling via ATM in Human Glioma Cells

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