| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Experimental Therapeutics |
Laboratory of Signal Transduction [L. A. P., R. N. K.] and Department of Radiation Oncology [L. A. P., Z. F.], Memorial Sloan-Kettering Cancer Center, New York, New York 10021
 |
ABSTRACT |
|---|
 Top ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
|
INTRODUCTION |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
In the CNS,3 there is a high degree of cellular heterogeneity, and both early and late injuries occur (3 , 4) . Whereas symptoms of acute and subacute injury can be reversed to some extent with steroid medication, the late forms of CNS injury are irreversible. The TD5/5–TD50/5 for single-dose exposure are 15–20 Gy and are similar for spinal cord myelopathy, brain white matter necrosis (leukoencephalopathy), and microvascular damage (1) . The pathogenesis of myelin degeneration and leukoencephalopathy is not fully understood. Whereas one hypothesis suggests that oligodendrocyte injury mediates this response, it is also possible that microvascular damage is a primary culprit (5, 6, 7) . Acute vascular changes within 24 h after irradiation include increased endothelial cell swelling, vascular permeability and edema, lymphocyte adhesion and infiltration, and apoptosis (1 , 8) . Late vascular effects occur weeks to months after irradiation and include capillary collapse, thickening of basement membranes, scarring and fibrosis, teleangiectasias, and a loss of clonogenic capacity (1 , 8) .
Despite the importance of radiation effects on the vascular endothelium in the CNS, there are little current in vivo data on endothelial cell death, and that which does exist is contradictory. A study of irradiated rodent brain showed that up to 15% of endothelial cells are lost within 24 h of irradiation (9) , the time frame in which apoptosis is most likely to occur. However, another study failed to detect any endothelial cell apoptosis within the same time frame (10 , 11) . The present work was undertaken to determine whether endothelial apo-ptosis occurs after CNS irradiation in a rodent model and to determine the mechanism of this response.
Recent studies have demonstrated that microvascular endothelial
apoptosis constitutes an early and critical element in radiation
pneumonitis and in the LPS-induced septic shock syndrome (12
, 13)
. The proapoptotic effects of radiation and of LPS were shown
to be mediated via the ASM and the generation of ceramide (13
, 14)
. Genetic mutations that inactivate ASM or treatment with
i.v. injections of bFGF abrogated ceramide generation and apoptosis.
The same mechanism of radiation-induced apoptosis via ceramide
generation was also observed in endothelial cells in vitro
(15)
, and the antiapo-ptotic action of bFGF
(16, 17, 18)
was shown to be mediated, at least in part, via
activation of the 
isoform of PKC (17)
. A similar
interaction between radiation, ceramide, PKC, and apoptosis was
reported in the SQ-20B squamous carcinoma cell line, in which radiation
failed to elicit an apoptotic response unless PKC was blocked, leading
to increased apoptosis and clonogenic cell death in vitro
and in vivo (19
, 20)
. Radiation-induced
apoptosis in lymphoid cells is similarly associated with a balance
between ceramide and PKC activity, although in this system, Bcl-2 also
regulated ceramide- and radiation-induced apoptosis (21
, 22)
. Similarly, a loss of neutral sphingomyelinase has been
shown to confer radiation resistance in WEHI-231 and TF-1 lymphoid
cells, in which a reduction in both clonogenic death and apoptotic
death was associated with deficient ceramide production (19
, 20
, 23) . Zundel and Giaccia (24)
have shown that stress
signals apoptosis via ceramide-induced down-regulation of
phosphatidylinositol 3'-kinase and inhibition of the kinase Akt/PKB.
Inhibition of this pathway resulted in decreased phosphorylation of
Bad, a death effector in the Bcl-2 family. Signaling via the kinase
suppressor of Ras/mitogen-activated protein kinase pathway may
also cause the inactivation of Akt/PKB and the dephosphorylation of
Bad, although direct data on ionizing radiation as the apoptotic
stimulus for this pathway are currently lacking (25)
.
Hence, radiation-induced apo-ptotic signaling through ceramide
appears to involve multiple, coordinated pathways, and the apoptotic
outcome in vitro and in vivo depends on the
balance between the activities of pro- and antiapo-ptotic signaling
systems.
In this report, we examined in vivo the extent and kinetics of CNS endothelial cell responses to radiation in the mature CNS of mice. Dose- and time-dependent induction of apoptosis was observed in the endothelium of the brain and spinal cord. A significant reduction of this apoptotic response was observed after i.v. bFGF treatment or in ASM KO mice. These radioprotective effects are consistent with an emerging body of evidence linking radiation-induced stress responses in endothelium with ceramide and suggest new approaches to modify the apoptotic response in the control of radiation toxicity in the CNS.
|
MATERIALS AND METHODS |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Irradiation.
Mice were lightly sedated with ketamine (0.1 mg/g), placed prone in a
137Cs irradiator (Shepherd Mark-I, Model 68), and
subjected to total body irradiation at a dose rate of 220 cGy/min. At
various time points, animals were euthanized and perfusion fixed
intracardially with fresh 4% paraformaldehyde in PBS. Brains and
spinal cords were dissected and post-fixed overnight and then placed in
an automated vacuum tissue processor for paraffin embedding over a 16-h
period. In some experiments, mice were also given i.v. injections of
recombinant bFGF or other cytokines (R&D Systems, Minneapolis, MN) in a
vehicle of 0.1% gelatin under metaphane anesthesia into the
retro-orbital plexus according to the following schedule: 5 min before
irradiation; immediately after irradiation; and 1 h after the
start of irradiation.
Apoptosis and Histochemical Analyses.
Noncontiguous 8-µm sections were mounted on slides, rehydrated, and
stained using the TUNEL method for detection of apoptosis in
situ, as described previously (16
, 27)
. Briefly,
slides were incubated with 3%
H2O2 in PBS for 5 min,
rinsed, and then incubated in TdT buffer [140 mM
cacodylate (pH 7.2), 30 mM Tris, and 1
mM CoCl2] for 15 min at
22°C. TdT reaction mixture was added [0.2 unit/µl TdT (Boehringer
Mannheim Roche; Indianapolis, IN), 2 nM
biotin-11-dUTP (Boehringer Mannheim Roche), 100
mM cacodylate (pH 7.0), 2.5
mM CoCl2, 0.1
mM DTT, and 0.05 mg/ml BSA] and incubated
for 30 min at 37°C. After blocking with 2% BSA and an incubation
with avidin-biotin peroxidase complexes (ABC kit; Vector Laboratories;
Burlingame, CA), the TUNEL reaction was visualized by chromogenic
staining with DAB (Sigma, St. Louis, MO). Slides were counterstained
with hematoxylin.
For immunohistochemical double labeling, TUNEL-stained sections were transferred at room temperature to TBST buffer, followed by blocking in 2% fetal bovine serum in TBST, three washes with PBS, and an overnight incubation at 4°C with rhodamine-conjugated LEL (Sigma) at a concentration of 25 µg/ml in PBS (28 , 29) . After two washes with TBST and one 1-h wash with water, coverslips were mounted with Permafluor (Shandon Lipshaw; Pittsburgh, PA). Two alternative endothelial markers were used: (a) biotinylated RCA-1 (Vector Laboratories) at 30 µg/ml (30, 31, 32, 33) followed by incubation with rhodamine-conjugated avidin (Vector Laboratories); or (b) antimouse CD31 monoclonal antibody (PharMingen; San Diego, CA) at a 1:50 dilution in PBS (13 , 34 , 35) followed by biotinylated antihamster IgG (PharMingen) at a 1:100 dilution [anti-CD31 was preceded by an antigen unmasking step of 20 min at 37°C with pepsin (Sigma; 60,000 units/ml) in water]. Stained slides were viewed with a Zeiss Axiophot-2 under light and/or epifluorescence illumination with rhodamine filter sets.
Cell counts of TUNEL- and double-labeled TUNEL + LEL-stained cells were counted manually in a single-blind fashion. Brown-stained nuclei immediately at the edge of a tissue section were excluded from cell counts to minimize false positives. Significant differences were determined by one-tailed Student’s t test. For simple counts of the total number of cells per spinal cord cross-section, digital photomicroscopy images were acquired with a SPOT-32 charge-coupled device camera and imported into ImagePro Plus (Media Cybernetics, Silver Spring, MD). After selecting a range of pixel color values corresponding to blue-stained nuclei, a software function generated cell count data, which were separately verified by comparing to several manually counted sections.
|
RESULTS |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
To further characterize the apoptotic response to radiation in the CNS,
time course and radiation dose-response studies were carried out. Fig. 1
depicts the dose response in spinal cord sections of duplicate mice at
several time points within a 24-h period. Previous work on the
radiation response of the mature rat CNS reported peak levels of
apoptosis in the subependymal zone of the brain that occurred at 6–8 h
after irradiation (38)
, and peak levels of apoptosis
occurred at 10–12 h in the spinal cord (10)
. Our analysis
of the adult mouse CNS confirmed this time course. The apoptotic
response was dose dependent and peaked at 12 after irradiation (Fig. 1
). Similar results could be observed in various regions of the brain,
e.g., hippocampus and pons (data not shown). For subsequent
experiments, the dose of 50 Gy was preferred to increase the
statistical significance of cell counting of low frequency events. This
dose is likely to have relevance to biological phenomena because
previous studies showed that single-dose radiation of less than 10 Gy
produced no morphological changes in the CNS, whereas significant early
or latent effects were seen with doses between 20 and 40 Gy
(39)
. Furthermore, fractionated radiation in the range of
45–60 Gy represents the lower tolerance threshold in humans
(40)
. Thus a 50 Gy single dose to the rodent CNS would be
expected to produce sublethal, subacute effects near the lower
tolerance threshold for the CNS (41)
.
|
).
|
shows double labeling of cells with LEL and TUNEL at high magnification
(x1000). An endothelial cell exhibiting intensely fluorescent LEL
staining (Fig. 2A
, top) is the same cell whose
apoptotic nucleus is TUNEL positive (Fig. 2A
, middle). These
images were digitally superimposed to demonstrate the colocalization of
these two markers (Fig. 2A
, bottom). Lectin stains can also
label microglia (30, 31, 32, 33)
, the resident tissue macrophages
of the CNS. The distinct morphology of microglia is demonstrated in
Fig. 2B
, whose significantly weaker staining has been
enhanced in this exposure only for the purposes of reproduction for
publication. The double stain studies revealed that the fraction of
endothelial cells in the total population of cells undergoing apoptosis
at 12 h after exposure to 50 Gy was 16–20%. The majority of
apoptotic cells that were nonendothelial are likely to be glial, based
on morphological criteria, in agreement with data reported by Li
et al. (10)
.
|
). All treated animals were significantly different from
sham-injected controls (P < 0.001). Similar
significant reductions in apoptosis were measured in two strains of
mice tested, C3H/HeJ and C57BL/6 (P < 0.001
each; Fig. 3B
). Differences between strains were not
significant (P = 0.08). To explore whether
the antiapoptotic effect of FGF was specific to the endothelial cell
subpopulation of the irradiated CNS, the double labeling technique with
TUNEL and LEL was used. Table 1
shows that similar to the effect of bFGF on the total cell population,
treatment with bFGF resulted in an approximately 50% reduction in
endothelial cell apoptosis. These ratios remained approximately the
same in separate experiments with varying doses of radiation (1, 5, 10,
and 20 Gy) and a constant dose of bFGF (data not shown). These data
indicated that whereas FGF may protect more than one of the
subpopulations of CNS cells, endothelial cells in vivo are
indeed definitely radioprotected, as has been observed previously
in vitro and in other organs in vivo (12
, 16
, 46, 47, 48, 49, 50)
.
|
). Quantitative differences between wild-type and ASM KO mice were also
evident in different regions of the brain, such as the hippocampus
(Fig. 5
) midbrain, and hindbrain (data not shown). Differences between
wild-type and ASM KO mice were significant (Table 2)
. TUNEL/LEL double staining to identify the endothelial cell
subpopulation showed a 3-fold difference between the wild-type and KO
strains (Table 3)
. These data suggest that the effect of radiation to induce apoptosis
in the cells of the CNS microvasculature is mediated via the
ASM/ceramide pathway.
|
|
|
|
|
DISCUSSION |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Our present studies also showed that 16–20% of the cells undergoing apoptosis were endothelial cells, whereas the rest involved glial subpopulations of the CNS parenchyma. It has been estimated that the number of endothelial cells in the adult mouse spinal cord is 2.50 x 106 of a total population of 13.08 x 106 cells (42) , representing approximately 20% of the total. Hence, the incidence of endothelial apoptosis was proportional to the endothelial cell fraction of the total CNS cell population. Whereas the peak incidence of endothelial apoptosis appears to be low, the overall apoptotic response over the first 24-h period after radiation may be considerable and significant for the generation of tissue responses. Consistent with this notion is the study by Ljubimova et al. (9) , which reported that 15% of the CNS endothelium is lost by 24 h after exposure to 25–100 Gy.
The fact that both endothelial cells and other parenchymal CNS cells undergo concomitant apoptosis leaves open the question of which component is critical to the evolution of acute radiation toxicity in the CNS. In previous studies, we demonstrated that microvascular endothelial apoptosis was the primary and critical response in the generation of tissue damage by radiation and other stresses. The microvascular endothelium was the earliest tissue component to undergo apoptosis in the irradiated lung of C3H/HeJ mice (12 , 16 , 17) and in the small intestine, lung, and fat tissue of C57BL/6 mice during experimental septic shock (13) . The critical role of this response in the evolution of tissue damage was suggested by the fact that both endothelial apoptosis and the eventual tissue damage were abrogated by i.v. bFGF therapy. Furthermore, ASM KO mice were found to be refractory to lung irradiation- and LPS-induced microvascular endothelial apoptosis, tissue damage, and animal death in response to these stresses (13 , 14) . The present studies showed that in the CNS, both FGF and ASM deficiency reduced radiation-induced apoptosis in the endothelial compartment. However, because endothelial apoptosis and nonendothelial apoptosis occur simultaneously, whether apoptotic damage to the microvasculature is critical to the pathogenesis of acute radiation damage to the adult mouse CNS remains unclear. The finding that bFGF and ASM deficiency reduces the apoptotic response to radiation provides a possible approach to further explore whether this acute apoptosis, over the long term, has relevance to early or late CNS injury.
Whereas the present studies provided evidence for radiation-induced endothelial apoptosis, prior investigations by Li et al. (10 , 11) failed to detect endothelial cell apoptosis in the irradiated CNS. Differences in the histochemical assays to identify the cell types undergoing apoptosis may have accounted for this apparent discrepancy. Whereas we used the TUNEL/LEL double labeling technique to distinguish between endothelial and nonendothelial apoptosis, Li et al. used single-agent staining with either the Leu-7 antibody, anti-GFAP antibody, or the RCA-1 lectin (10 , 11) . In the Li et al. studies, apoptotic cells were stained only by the Leu-7 antibody, leading to the conclusion that only oligodendrocytes undergo apoptosis in response to CNS irradiation. Leu-7 labels the myelin-associated glycoprotein of oligodendrocytes and oligodendrogliomas because the carbohydrate residues of this protein contain the HNK-1 epitope (51, 52, 53) . However, the HNK-1 epitope also occurs in a class of glycolipids known as sulfoglucuronosyl paraglobosides, which are present in brain microvascular endothelial cells (54, 55, 56) . These sulfo-glycolipids are thought to mediate activated lymphocyte attachment to endothelial cells and subsequent infiltration into the parenchyma of the CNS. The HNK-1 epitope has also been found on neurons (57 , 58) and immature astrocytes (52) , in addition to the population of natural killer cells and T-lymphocytes from which it was originally described (59) . Hence, Leu-7/HNK-1 staining appears to lack specificity and may stain CNS endothelial cells in addition to oligodendrocytes.
The present observations are also consistent with a large body of data demonstrating survival effects for FGF on several CNS cell types in vivo after a variety of injuries or stresses (for review, see Refs. 60, 61, 62, 63, 64, 65, 66 ). Furthermore, FGF has been shown to exert radioprotective effects in several non-CNS tissue systems in vivo. Ding et al. (46, 47, 48) and Okunieff et al. (49 , 50) have reported that in C3H mice, both bFGF and, to a lesser extent, aFGF exhibit radioprotective effects in lymphoid cells and intestinal crypt cells, and our group has previously observed protection by bFGF in the lung (12 , 13 , 16) . Although the mechanisms involved in the radioprotective effects of FGF are not fully known, evidence suggests that PKC, which serves as the effector system mediating the radioprotective effect of bFGF in primary cultures of bovine endothelium, may act by blocking sphingomyelin hydrolysis to ceramide (15 , 17) . Oligodendrocytes and other glial cells (61 , 62 , 67 , 68) express FGF receptors, and oligodendrocyte apoptosis has been linked to ceramide generation in some instances (for a review, see Ref. 69 ). Whether bFGF protects glial elements from radiation-induced apoptosis directly or indirectly by preserving microvessels cannot be answered by the present data. Derivatized forms of bFGF, either biotinylated or radiolabeled with 111In or 125I, failed to gain access to the parenchyma of the brain and remained in the intima of capillaries (16 , 70) , and lacked protective effects, whereas metabolically labeled [14C]bFGF freely crossed the blood brain barrier and exerted protective effects (71) . Further experimentation is necessary to determine whether FGF is effective in abrogating the deleterious tissue effects of radiation on the CNS and whether it is mediated via an antiapoptotic effect on oligodendrocytes, endothelial cells, or both. The study of ASM KO mice may be useful for this distinction.
ACKNOWLEDGMENTS
We thank M. Sockie Jiao and Desiree A. Ehleiter for outstanding
technical support and Drs. Mark Garzotto and Adriana Haimovitz-Friedman
for scientific advice.
|
FOOTNOTES |
|---|
1 Supported by NIH/National Cancer Institute
Research Career Development Award K01-CA-76483 (to L. A. P.) and NIH
Grants CA-52462 (to Z. F.) and CA-42385 (to R. N. K.). 
2 To whom requests for reprints should be
addressed, at Laboratory of Signal Transduction, Memorial
Sloan-Kettering Cancer Center, 1275 York Avenue, Box 254, New York, NY
10021. Phone: (212) 639-8573; Fax: (212) 639-2767; E-mail: r-kolesnick{at}ski.mskcc.org
3 The abbreviations used are: CNS, central nervous
system; ASM, acid sphingomyelinase; FGF, fibroblast growth factor;
bFGF, basic FGF; TdT, terminal deoxynucleotidyl transferase; TUNEL,
TdT-mediated nick end labeling; LPS, lipopolysaccharide; PKC, protein
kinase C; KO, knockout; TBST, 50 mM Tris (pH 7.5), 150
mM NaCl, and 0.1% Triton X-100; LEL, Lycopersicon
esculentum lectin; RCA-1, Ricinus communis
agglutinin 1; aFGF, acidic FGF; DAB, 3,3'-diaminobenzidine
tetrachloride.
Received 7/27/99. Accepted 11/15/99.
|
REFERENCES |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
, and ceramide. Cancer Res., 55: 991-994, 1995.. Blood, 92: 416-424, 1998.This article has been cited by other articles:
|
|
 |
|
  M.-L. Alvarez Gonzalez, F. Frankenne, C. Galant, E. Marbaix, J.-M. Foidart, M. Nisolle, and A. Beliard Mixed origin of neovascularization of human endometrial grafts in immunodeficient mouse models Hum. Reprod., September 1, 2009; 24(9): 2217 - 2224. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Cao, C. I. Tsien, P. C. Sundgren, V. Nagesh, D. Normolle, H. Buchtel, L. Junck, and T. S. Lawrence Dynamic Contrast-Enhanced Magnetic Resonance Imaging As a Biomarker for Prediction of Radiation-Induced Neurocognitive Dysfunction Clin. Cancer Res., March 1, 2009; 15(5): 1747 - 1754. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. L. Smith and E. H. Schuchman The unexpected role of acid sphingomyelinase in cell death and the pathophysiology of common diseases FASEB J, October 1, 2008; 22(10): 3419 - 3431. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Bonnaud, C. Niaudet, G. Pottier, M.-H. Gaugler, J. Millour, J. Barbet, L. Sabatier, and F. Paris Sphingosine-1-Phosphate Protects Proliferating Endothelial Cells from Ceramide-Induced Apoptosis but not from DNA Damage-Induced Mitotic Death Cancer Res., February 15, 2007; 67(4): 1803 - 1811. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
X. W. Huang, J. Yang, A. F. Dragovic, H. Zhang, T. S. Lawrence, and M. Zhang Antisense oligonucleotide inhibition of tumor necrosis factor receptor 1 protects the liver from radiation-induced apoptosis. Clin. Cancer Res., May 1, 2006; 12(9): 2849 - 2855. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Gulbins and P. L. Li Physiological and pathophysiological aspects of ceramide Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2006; 290(1): R11 - R26. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. C. Stover, A. Sharma, G. P. Robertson, and M. Kester Systemic Delivery of Liposomal Short-Chain Ceramide Limits Solid Tumor Growth in Murine Models of Breast Adenocarcinoma Clin. Cancer Res., May 1, 2005; 11(9): 3465 - 3474. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Otala, M. O. Pentikainen, T. Matikainen, L. Suomalainen, J. K. Hakala, G. I. Perez, M. Tenhunen, K. Erkkila, P. Kovanen, M. Parvinen, et al. Effects of Acid Sphingomyelinase Deficiency on Male Germ Cell Development and Programmed Cell Death Biol Reprod, January 1, 2005; 72(1): 86 - 96. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M Akashi Role of infection and bleeding in multiple organ involvement and failure Br. J. Radiol., January 1, 2005; Supplement_27(1): 69 - 74. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M-H Gaugler A unifying system: does the vascular endothelium have a role to play in multi-organ failure following radiation exposure? Br. J. Radiol., January 1, 2005; Supplement 27(1): 100 - 105. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. S. Wong and A. J. Van der Kogel MECHANISMS OF RADIATION INJURY TO THE CENTRAL NERVOUS SYSTEM: IMPLICATIONS FOR NEUROPROTECTION Mol. Interv., October 1, 2004; 4(5): 273 - 284. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Woywodt, J. Scheer, L. Hambach, S. Buchholz, A. Ganser, H. Haller, B. Hertenstein, and M. Haubitz Circulating endothelial cells as a marker of endothelial damage in allogeneic hematopoietic stem cell transplantation Blood, May 1, 2004; 103(9): 3603 - 3605. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y.-Q. Li, P. Chen, A. Haimovitz-Friedman, R. M. Reilly, and C. S. Wong Endothelial Apoptosis Initiates Acute Blood-Brain Barrier Disruption after Ionizing Radiation Cancer Res., September 15, 2003; 63(18): 5950 - 5956. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Abdollahi, K. E. Lipson, X. Han, R. Krempien, T. Trinh, K. J. Weber, P. Hahnfeldt, L. Hlatky, J. Debus, A. R. Howlett, et al. SU5416 and SU6668 Attenuate the Angiogenic Effects of Radiation-induced Tumor Cell Growth Factor Production and Amplify the Direct Anti-endothelial Action of Radiation in Vitro Cancer Res., July 1, 2003; 63(13): 3755 - 3763. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Wachsberger, R. Burd, and A. P. Dicker Tumor Response to Ionizing Radiation Combined with Antiangiogenesis or Vascular Targeting Agents: Exploring Mechanisms of Interaction Clin. Cancer Res., June 1, 2003; 9(6): 1957 - 1971. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Maddens, A. Charruyer, I. Plo, P. Dubreuil, S. Berger, B. Salles, G. Laurent, and J.-P. Jaffrezou Kit signaling inhibits the sphingomyelin-ceramide pathway through PLCgamma 1: implication in stem cell factor radioprotective effect Blood, July 30, 2002; 100(4): 1294 - 1301. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X. Li, L. Liu, J. C. Tupper, D. D. Bannerman, R. K. Winn, S. M. Sebti, A. D. Hamilton, and J. M. Harlan Inhibition of Protein Geranylgeranylation and RhoA/RhoA Kinase Pathway Induces Apoptosis in Human Endothelial Cells J. Biol. Chem., May 3, 2002; 277(18): 15309 - 15316. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Nagasawa, A. Cremesti, R. Kolesnick, Z. Fuks, and J. B. Little Involvement of Membrane Signaling in the Bystander Effect in Irradiated Cells Cancer Res., May 1, 2002; 62(9): 2531 - 2534. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Ganss, E. Ryschich, E. Klar, B. Arnold, and G. J. Hammerling Combination of T-Cell Therapy and Trigger of Inflammation Induces Remodeling of the Vasculature and Tumor Eradication Cancer Res., March 1, 2002; 62(5): 1462 - 1470. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Ozen, D. Giri, F. Ropiquet, A. Mansukhani, and M. Ittmann Role of Fibroblast Growth Factor Receptor Signaling in Prostate Cancer Cell Survival J Natl Cancer Inst, December 5, 2001; 93(23): 1783 - 1790. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Levade, N. Auge, R. J. Veldman, O. Cuvillier, A. Negre-Salvayre, and R. Salvayre Sphingolipid Mediators in Cardiovascular Cell Biology and Pathology Circ. Res., November 23, 2001; 89(11): 957 - 968. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Paris, Z. Fuks, A. Kang, P. Capodieci, G. Juan, D. Ehleiter, A. Haimovitz-Friedman, C. Cordon-Cardo, and R. Kolesnick Endothelial Apoptosis as the Primary Lesion Initiating Intestinal Radiation Damage in Mice Science, July 13, 2001; 293(5528): 293 - 297. [Abstract] [Full Text]
|
|
|
|
|
|
H.-P. DEIGNER, R. CLAUS, G. A. BONATERRA, C. GEHRKE, N. BIBAK, M. BLAESS, M. CANTZ, J. METZ, and R. KINSCHERF Ceramide induces aSMase expression: implications for oxLDL-induced apoptosis FASEB J, March 1, 2001; 15(3): 807 - 814. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Selzner, A. Bielawska, M. A. Morse, H. A. Rüdiger, D. Sindram, Y. A. Hannun, and P.-A. Clavien Induction of Apoptotic Cell Death and Prevention of Tumor Growth by Ceramide Analogues in Metastatic Human Colon Cancer Cancer Res., February 1, 2001; 61(3): 1233 - 1240. [Abstract] [Full Text]
|
|
|
|
|
|
J. Lozano, S. Menendez, A. Morales, D. Ehleiter, W.-C. Liao, R. Wagman, A. Haimovitz-Friedman, Z. Fuks, and R. Kolesnick Cell Autonomous Apoptosis Defects in Acid Sphingomyelinase Knockout Fibroblasts J. Biol. Chem., January 5, 2001; 276(1): 442 - 448. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Paris, H. Grassme, A. Cremesti, J. Zager, Y. Fong, A. Haimovitz-Friedman, Z. Fuks, E. Gulbins, and R. Kolesnick Natural Ceramide Reverses Fas Resistance of Acid Sphingomyelinase-/- Hepatocytes J. Biol. Chem., March 9, 2001; 276(11): 8297 - 8305. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |
-radiation at various doses, and the CNS
was harvested at various time points, as indicated. Paraffin-embedded
cross sections of the spinal cord were stained using the TUNEL method,
and the number of positively stained nuclei was counted
(n = 2 mice, 8–12 sections/mouse). SE
was <10%.
