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Experimental Therapeutics |
Division of Neuro-Oncology [B. G., K. K., C-B. T., P. C. P., A. J. J.], Department of Neurosurgery [L. N. S.], and Pathology [B. P.], Children’s Hospital of Philadelphia, and Department of Pathology [K-M. F.], Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104
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ABSTRACT |
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 Top ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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INTRODUCTION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Antitumor activity of rapamycin as a single agent has been described in vitro and in vivo (9, 10, 11, 12, 13) . Coadministration enhanced cisplatin-induced apoptosis in human cell lines (14) and produced additive cytotoxicity with 5-fluouracil and cyclophosphamide in a Colon 38 tumor model (13) .
PNET/MB3 are the most common malignant brain tumors in childhood. With current treatment, including radio- and chemotherapy subsequent to surgical resection, the 5-year survival rate for PNET/MB exceeds 80% (15 , 16) . However, 30–50% of all patients experience tumor progression or late relapse with very low salvage rates (17) . Therefore, improving the long-term survival of patients with high risk PNET/MB will require therapeutic strategies that augment the effects of current treatment.
Rapamycin and its analogue, CCI-779, are attractive candidates for brain tumor therapy. Their unusual mechanism of action make it unlikely that these agents will interfere with the cytotoxicity of standard chemotherapeutic agents or exhibit cross-resistance. They are highly lipophilic (18) and thus able to penetrate the blood-brain barrier. Finally, rapamycin has minimal systemic toxicity in animals or humans (19, 20, 21, 22) . In vitro studies in our laboratory find that brain tumor cell lines can be exquisitely sensitive to rapamycin. For example, the PNET/MB cell line DAOY has an ID90 =102 ng/ml. In contrast, the PNET/MB D283 and malignant glioma U251 cell lines are highly resistant, with ID90 values of 1.8 x 106 and 3.6 x 1019 ng/ml, respectively.4
Here, we describe preclinical investigations of rapamycin and CCI-779 in treatment of human brain tumors. The cytotoxicity of rapamycin was measured using brain tumor cell lines in culture; the cytotoxicity of CCI-770 was measured using s.c. brain tumor xenografts and in combination with cisplatin and CPT. Our results indicated that rapamycin in vitro and CCI-779 in vivo exhibited additive cytotoxicity in PNET/MB cells when combined with cisplatin or CPT. In vivo studies showed that the same dose of CCI-779 given in daily injections over 2 weeks produced greater tumor suppression than when given as a single injection. Four weeks of daily CCI-779 injections were not superior to 2 weeks in the induction of tumor regression and growth retardation of human PNET/MB xenografts. Finally, CCI-779 suppressed the growth of human U251 malignant glioma cells in vivo despite the resistance of the cell line to rapamycin cytotoxicity in vitro.
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MATERIALS AND METHODS |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Drugs.
Rapamycin and CCI-779 were obtained from Wyeth-Ayerst Research
Laboratories (Princeton, NJ), CPT from Smith-Kline Beecham
Pharmaceuticals, and cisplatin from Sigma Pharmaceuticals. Rapamycin
and CCI-779 were stored as dry powder at -20°C and suspended in
100% ethanol the day of use. CPT was stored as a 5-mM
solution in DMSO and cisplatin as a 5-mM solution in
sterile water at -20°C.
In Vitro Assay for Cytotoxicity.
Cytotoxicity of rapamycin, CPT, and cisplatin were assessed for
unsynchronized DAOY and D283 cells by MTS tetrazolium Cell Titer 96 AQ
Non-Radioactive Cell Proliferation assay (Promega, Madison, WI). DAOY
and D283 cells were plated in 96-well plates, 500 cells/well. After
24 h, rapamycin, CPT, and cisplatin, diluted in serum-free Zinc
Option Medium immediately before use, were added to the media as single
agents or in combination (rapamycin plus CPT or rapamycin plus
cisplatin). Each drug dose or combined drug dose was repeated five
times. After 5 days of drug exposure, MTS solution was added to
each well, and absorbance was measured at 490 nm. Experimental
absorbance was computed by subtracting the absorbance of blank wells
(media only). Fractional survival was computed as: experimental
absorbance (mean of 5 trials/dose or dose combination)/absorbance for
cells treated with drug free media (mean of 15 trials).
Analysis of in Vitro Drug Interaction.
An additivity model was used as described previously (24)
.
The additive cytotoxicity of a drug/dose combination is defined as the
sum of cell kill for each agent tested as a single drug, with a 90%
confidence interval for this sum. Antagonistic cytotoxicity is defined
as a drug interaction that caused less cytotoxicity than the sum of
each agent used alone (i.e., less than additivity), and
synergy is defined as the combined effect of drugs that is greater than
the sum of the cytotoxicity for each agent used alone (i.e.,
greater than additivity). The treatment effect for each agent at
a given dose was identified by means of single-agent dose-effect curves
(25
, 26)
. Cytotoxicity of single agents was characterized
further by fitting dose-response curves to a linear model by means of
regression analysis with transformations of the response
(i.e., fractional survival) and the log of the dose. These
transformations permit the calculation of 95% confidence intervals for
single agent dose-response curves and the subsequent calculation of a
90% confidence interval for the expected additive cytotoxicity. Drug
interaction was characterized by comparing the observed cytotoxicity of
a drug combination with the expected additive cytotoxicity.
In Vivo Human DAOY-MB and U251 Malignant Glioma
Xenograft Models.
Female athymic nude mice 4–6 weeks of age were purchased from the
National Cancer Institute (Frederick, MD) and maintained in
filter-top cages in an aseptic environment with laminar flow filtered
ventilation at the Laboratory Animal Facility of the Joseph Stokes,
Jr., Research Institute of the Children’s Hospital of Philadelphia.
DAOY-MB xenograft experiments were performed with DAOY tumors that had
undergone at least eight serial passages as xenograft tumors in the
flanks of nude mice. The flank xenograft tumors of stock animals were
dissected free of connective tissue and external vasculature in a
sterile laminar flow hood. The tumors were coarsely minced and then
passed through a 20-mesh screen in a tissue press. The xenograft
homogenate was passed sequentially through a 20-, 21-, 22-, and
23-gauge needle. The tumor homogenate (0.15 ml) was injected
s.c. through a 23-gauge needle into the right flank of each nude mouse.
For U251 xenografts, U251 cells grown in in vitro cell
cultures were harvested in log-phase and resuspended in Matrigel (Life
Technologies, Inc.). Cells (1 x 107) in 0.15 ml per animal were injected
into the right flank of athymic nude mice. The length and width (mm) of
s.c. tumors were measured every 2–3 days with Vernier calipers
(Fischer Scientifics). Tumor volume was calculated by the following
formula: width (2)
x length/2
(27)
.
Treatment with CCI-779 and/or Cisplatin.
Nude mice bearing s.c. DAOY flank xenograft tumors were treated
starting on day 10; animals bearing U251 xenografts were treated
starting 3 weeks after tumor implantation. Stock dilution of CCI-779 50
mg/kg was diluted to a final concentration of 2 mg/ml using a diluent
of 5% Tween 80 and 5% polyethylene glycol 400. The efficacy of
different treatment schedules was tested in DAOY/MB xenografts. Each
treatment group consisted of five to six animals. CCI-779 (20
mg/kg) was administered daily x 5 for 1, 2 or 4 weeks;
or 100 mg/kg of CCI-779 was administered on days 1 and 12. Drug
interaction of CCI-779 in vivo was studied by injection of 5
mg/kg cisplatin as a single dose, with or without daily treatment of 20
mg/kg CCI-779 x 5 for 2 weeks. U251 xenograft tumors
were treated with daily with 20 mg/kg CCI-779 x 5 for 2
weeks. Control animals bearing s.c. flank tumors were treated with
diluent at equivalent doses and schedule.
Tumor volumes were measured serially and normalized by the index of observed tumor volume in comparison to initial, pretreatment tumor volume (Vo/Vi). Growth delay end points were defined as the posttreatment interval at which tumor volume increased by 5-fold (27) . The Wilcoxon-Gehan Test was used to evaluate differences in time to reach 5-fold initial tumor volume (28) .
Histology.
Nude mice with DAOY-MB xenografts were treated on day 10 after tumor
inoculation with either 100 mg/kg CCI-779, 5 mg/kg cisplatin, or both,
or diluent, as described above in treatment studies. Animals were
killed electively 4 days after this treatment. Flank tumors were
harvested, fixed in 10% formalin, paraffin-embedded and cut into
microsections. Sections were stained with H&E for morphology.
Proliferation.
Immunohistochemistry for Ki-67 antigen was performed to determine the
proliferation indices of the xenograft tumors. A monoclonal
MIB-1 antibody (1:50; Immunotech, Marseilles, France) was used,
detected by the Animal Research Kit (ARK; DAKO Corporation,
Carpinteria, CA) according to the manufacturer’s instructions, with
biotinylated Fab antimouse antibody, Streptavidin-horseradish
peroxidase, and diaminobenzidine tetrahydrochloride (DAKO Corporation).
For quantification, tumor cells were counted at x1000. The
proliferation index was expressed as the number of MIB-1 positive
cells/100 neoplastic cells.
Apoptosis.
TUNEL was performed to quantify apoptotic cell death. A modified
protocol according to Gavrieli et al. (29)
was
used. In brief, tissue sections were deparaffinized, rehydrated, and
treated with 10 µg/ml Proteinase K (Boehringer Mannheim,
Indianapolis, IN) for 15 min at room temperature. DNA strand breaks
were labeled by polymerization of 30 µM
digoxigenin-11-dUTP (Boehringer Mannheim, Indianapolis, IN) to the
3'-OH sites, catalyzed by 0.3 units/µl terminal deoxynucleotidyl
transferase (Boehringer Mannheim, Indianapolis, IN) for 45 min at
37°C. Labeled DNA breaks were revealed by anti-digoxigenin Fab
fragments conjugated with alkaline phosphatase (Boehringer Mannheim) at
a dilution of 1:200. The labeled DNA strands were visualized using Fast
Red (Sigma, St. Louis, MO). Terminal deoxynucleotidyl
transferase or the biotinylated dUTP was omitted for negative
controls; sections of a postnatal day-8 rat brain were used for
positive controls. To quantify TUNEL-positive cells, at least 2000
tumor cells were counted at 400X magnification. Labeled cells
displaying compaction or segregation of the nuclear chromatin, or
breaking up of the nucleus into discrete fragments, were counted as
apoptotic cells. Labeled cells adjacent to or within necrotic areas
were not counted. The apoptotic index (AI) was expressed as the number
of TUNEL-positive cells/100 tumor cells.
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RESULTS |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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. We selected concentrations of rapamycin from 0.001–1
ng/ml to evaluate drug interaction with cisplatin and CPT. Rapamycin
augmented cisplatin- and CPT-induced cytotoxicity in DAOY/MB
cells in a dose-dependent fashion. To evaluate drug interaction
objectively, the additivity model described in "Materials and
Methods" was used; r2 values for
single-agent regression curves were 0.867, 0.941, and 0.888 for
survival curves of rapamycin, cisplatin, and CPT, respectively. Using
this model, simultaneous treatment of DAOY/MB cells with rapamycin and
cisplatin resulted in additive cytotoxicity; the efficacy of cisplatin
and 1 ng/ml rapamycin was increased 100-fold relative to cisplatin
alone (Fig. 1B)
. Similar results were observed when
rapamycin was combined with CPT (Fig. 1C)
.
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.
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. CCI-779 administered at 20 mg/kg 5 days/week for 1 and 2 weeks yielded
1.6- and 2.4-fold delayed tumor growth (Fig. 3)
. Time to reach 5-fold tumor volume was significantly greater in
animals treated for 1 week or 2 weeks compared with control animals
(see Table 1
). Retreatment of large tumors with CCI-779 for 2 weeks (20
mg/kg i.p. 5 days/week on days 29 to 42) restored growth
inhibition but did not yield tumor regression (Fig. 3)
. Treatment with
CCI-779 (20 mg/kg i.p.) 5 days/week for 4 weeks delayed time to reach
5-fold pretreatment volume by 174% compared with controls (see Table 1
). Thus, prolonged treatment is not more efficacious than 2-week
treatment. A growth delay >50 days was observed in 20% of animals
treated 2 or 4 weeks but not in those treated 1 week.
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. However, unlike tumors treated with daily CCI-779, tumors treated
with the single high dose resumed growth after 1 week. Animals bearing
these tumors were given a second treatment with 100 mg/kg i.p. on day
12, but did not achieve a second growth regression. Time to reach
5 x pretreatment volume was 14 days in the treatment
group compared with 10.5 days in controls (see Table 1
).
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CCI-779 Induced Growth Delay in U251 Malignant Glioma Xenografts.
To determine whether the resistance to rapamycin observed in
vitro occurs in vivo, we used xenografts derived from
U251 malignant glioma cells, a cell line resistant to rapamycin
in vitro but reportedly sensitive in vivo
(12)
. Animals bearing U251 tumor xenografts were treated
with CCI-779 (20 mg/kg i.p. 5 days/week) for 2 weeks. As shown in Table 1
and Fig. 5
, time to grow to 5-fold pretreatment tumor volume was 40 days with
treatment compared with 27 days in control animals, a delay of 148%.
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and Fig. 6
).
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. The MIB-1 index was 44–48/100 tumor cells, and
TUNEL-positive cells occurred in 3.75/100 tumor cells.
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, and exhibited more proliferation and apoptosis
(20–41% of cells stained form MIB-1 and 5% were
TUNEL-positive) when compared with tumors from control mice
harvested the same day after implantation. DAOY xenografts in mice
treated with CCI-779 alone (Fig. 7C)
showed lower
proliferation activity than those in controls (18 and 17%
MIB-1-positive cells), but not increased apoptosis (2.5%
TUNEL-positive cells). DAOY tumors from mice treated with cisplatin and
CCI-779 were smaller than controls and exhibited large areas of
necrosis, hyalinization, and hemosiderin deposition (Fig. 7D)
. Tumor cells surrounding the central necrosis exhibited
18–38% MIB-1-labeling and 5.5% TUNEL-labeling. |
DISCUSSION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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This report documents the additive cytotoxicity of rapamycin and CCI-779 when combined with a platinating agent or a topoisomerase I inhibitor, classes of drugs currently used clinically for PNET/MB (15 , 30) . We found that cytotoxic efficacy in vitro and tumor regression in vivo were modulated by dosing schedule. Furthermore, this report is the first to document the cytotoxicity of rapamycin analogue CCI-779 in human PNET/MB and malignant glioma xenograft tumors both as a single agent and in combination with cisplatin. This supports previous reports that in vitro resistance does not accurately predict the efficacy of this agent in vivo and demonstrates that tumor toxicity can be increased by using combination chemotherapy without the risk of increased systemic cytotoxicity.
The antitumor activity of CCI-779 in vivo was tested using four distinct treatment schedules. Nude mice engrafted with human DAOY flank xenografts treated systemically with CCI-779 20 mg/kg daily 5 times per week exhibited significant delay of tumor growth. Treatment for 2 weeks was superior to shorter and longer treatment intervals. CCI-779 retreatment during xenograft expansion after treatment-induced growth delay restored growth inhibition, suggesting efficacy even for bulky tumors. Single high-dose treatment with CCI-779 achieved transient tumor regression, however, overall tumor growth delay was inferior to the equivalent dose given daily over a week. Previous studies examining antitumor activity of rapamycin in vivo used higher doses and different treatment schedules. For example, Houchens et al. (12) used 200, 400, and 800 mg/kg rapamycin i.p. on days 2, 6, and 10 to treat U251 malignant glioma xenografts, whereas Eng et al. (13) reported on the antitumor activity of 100 mg/kg i.p. for 9 days or 400 mg/kg i.p. on days 2 and 9 in melanoma, ependymoblastoma, and Colon 38 tumor models. In vitro results demonstrated a dose threshold of 1 ng/ml in DAOY, above which additional cytotoxicity is not achieved. In vivo results support the absence of a linear dose-response relationship in these tumors. Accordingly, our results indicate that high doses are not necessary for antitumor activity.
In vitro studies of rapamycin identify an interesting
pattern of tumor cell response: either exquisite sensitivity or
profound resistance (9
, 11)
. Evaluation of brain tumor
cell lines in our laboratory show a similar pattern. Four PNET/MB cell
lines were highly sensitive to growth inhibition by rapamycin in
vitro (IC50 
10 ng/ml), whereas
three PNET/MB cell lines and the U251 malignant glioma cell line were
nearly resistant (IC50 > 1000
ng/ml).5
No cell lines tested exhibited intermediate sensitivity. The
mechanism(s) determining resistance or sensitivity to rapamycin is
still under investigation. Sensitivity of cancer cell lines may be
attributable to the inhibition of insulin-like growth factor-I
receptor-mediated signaling by rapamycin, which is essential for
proliferation in some tumor cells (i.e., alveolar RMS cell
lines; Ref. 11
). Cellular resistance to rapamycin
has been correlated to paracrine growth factor signaling pathways
(9)
, the failure to inhibit c-Myc induction, mammalian
target of rapamycin mutants (11)
, and GLI
zinc finger protein (31)
. Nevertheless, CCI-779 treatment
induced tumor growth delay in nude mice bearing U251 xenografts, a cell
line highly resistant to rapamycin in vitro. Houchens
et al. (12)
report similar results using
rapamycin to treat U251 xenografts, suggesting that resistance to
rapamycin and its analogues documented in vitro does not
accurately predict resistance in vivo.
Rapamycin exhibits the same activity in the Colon 38 tumor model when administered i.p., i.v., i.m., and s.c.; upon p.o. administration, its activity was reduced but not abolished (13) .
Because of its high lipophilic index (18) , rapamycin easily crosses the blood-brain-barrier, which is important for systemic administration in the treatment of brain tumors. Pharmacological studies of rapamycin show that rapamycin is cleared rapidly from the blood after s.c. or p.o. administration and sequestered intracellularly, particularly in erythrocytes. It dissociates slowly from intracellular FK506-binding protein-12 and is metabolized by cytochrome p450 3A enzyme (8) . This may explain its long half-life in vivo (57–62 h in renal transplant patients; Ref. 32 ).
Rapamycin induces reduction of tumor growth with little systemic toxicity as compared with other antitumor drugs. In our hands, animals treated with a single dose of 100 mg/kg did not experience any obvious drug toxicity. With daily treatment for >2 weeks (20 mg/kg 5 days/week) animals experienced weight loss and dermatitis. Weight loss, increase in blood glucose concentrations, gastric ulceration, and thrombocytopenia have been described by others (19 , 21 , 33) . Eng et al. (13) reported the LD50 of rapamycin in mice as 587 mg/kg, yet in an earlier study no significant side effects were mentioned when doses up to 800 mg/kg were used (12) . Clinical Phase III trials designed to evaluate rapamycin as an immunosuppressant have demonstrated minimal systemic toxicity (20 , 22) . Two clinical Phase I trials of CCI-779 in patients with advanced tumors are currently ongoing. CCI-779 dose escalation from 7.5–60 mg/kg i.v. in a weekly dose did not induce grade III-IV nor dose-limiting toxicity. Neither significant immunosuppression nor opportunistic infections were observed (34) .
Cisplatin- and topoisomerase I-inhibitors such as camptothecin, CPT 11, and topotecan are effective agents in the chemotherapeutic treatment of brain tumors (15 , 30) . However, high doses lead to severe multiorgan toxicities (35) that limit the ability of dose intensification to increase treatment efficacy and patient survival. CCI-779 is a compelling candidate for novel adjuvant anticancer treatment because of limited toxicity and preclinical studies indicating additive cytotoxicity with several chemotherapeutic agents. Eng et al. found that rapamycin enhanced the cytotoxicity of 5-fluorouracil and cyclophosphamide when the drugs were administered sequentially in Colon 38 tumor-bearing mice, and that this combination was more effective than 5-fluorouracil-adriamycin-cyclophosphamide (13) . Using DAOYcells, we demonstrated the additive cytotoxicity of rapamycin with cisplatin and camptothecin in vitro and the enhanced antitumor effect of CCI-779 with cisplatin in vivo. Not only did simultaneous administration of CCI-779 and cisplatin delay xenograft growth, but pathological inspection revealed large areas of central necrosis in the tumors of mice receiving combination chemotherapy far less evident than in the tumors of mice treated with single agent. These data support a role for the use of the rapamycin analogue CCI-779 in combination chemotherapy in the treatment of PNET/MB.
In conclusion, this study documents the cytotoxicity of rapamycin and its analogue, CCI-779, in brain tumor models alone and in combination with other antitumor chemotherapy. This class of agents with a novel mechanism of action, low toxicity, and additive cytotoxicity in combination therapy has great potential in the treatment of human brain tumors including PNET/MB and malignant glioma.
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FOOTNOTES |
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1 B. G. is supported by the NIH (Grant POI-NS
34514), by the Dr. Mildred Scheel Stiftung Deutsche Krebshilfe e.V.,
and by the Jeffrey Miller Neuro-Oncology Research Fund. 
2 To whom requests for reprints should be
addressed, at Children’s Hospital of Philadelphia, Division of
Neuro-Oncology, 3400 Civic Center Boulevard, Philadelphia, PA 19104.
Phone: (215) 590-5170; Fax: (215) 590-3709; E-mail: janss{at}email.chop.edu
3 The abbreviations used are: PNET/MB, primitive
neuroectodermal tumor/medulloblastoma; CPT, camptothecin; TUNEL,
terminal deoxynucleotidyl transferase-mediated dioxygenin-11-dUTP nick
end labeling.
Received 6/29/00. Accepted 12/15/00.
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REFERENCES |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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—Pseudomonas exotoxin fusion protein (TGF--PE38) treatment of subcutaneous and intracranial human glioma and medulloblastoma xenografts in athymic mice.. Cancer Res., 54: 1008-1015, 1994.This article has been cited by other articles:
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  F. Meric-Bernstam and A. M. Gonzalez-Angulo Targeting the mTOR Signaling Network for Cancer Therapy J. Clin. Oncol., May 1, 2009; 27(13): 2278 - 2287. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Y. Zhao, A. Auerbach, A. M. D'Costa, A. P. Rapoport, A. M. Burger, E. A. Sausville, S. A. Stass, F. Jiang, A. M. Sands, N. Aguilera, et al. Phospho-p70S6K/p85S6K and cdc2/cdk1 Are Novel Targets for Diffuse Large B-Cell Lymphoma Combination Therapy Clin. Cancer Res., March 1, 2009; 15(5): 1708 - 1720. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Yang, M. J. Clarke, B. L. Carlson, A. C. Mladek, M. A. Schroeder, P. Decker, W. Wu, G. J. Kitange, P. T. Grogan, J. M. Goble, et al. PTEN Loss Does Not Predict for Response to RAD001 (Everolimus) in a Glioblastoma Orthotopic Xenograft Test Panel Clin. Cancer Res., June 15, 2008; 14(12): 3993 - 4001. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. J Houghton, J. B Easton, and R. T Kurmasheva mTOR as a Target for Cancer Therapy Am. Assoc. Cancer Res. Educ. Book, April 12, 2008; 2008(1): 111 - 120. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. S. Ziegler, A. L. Kung, and M. W. Kieran Anti-Apoptosis Mechanisms in Malignant Gliomas J. Clin. Oncol., January 20, 2008; 26(3): 493 - 500. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Fouladi, F. Laningham, J. Wu, M. A. O'Shaughnessy, K. Molina, A. Broniscer, S. L. Spunt, I. Luckett, C. F. Stewart, P. J. Houghton, et al. Phase I Study of Everolimus in Pediatric Patients With Refractory Solid Tumors J. Clin. Oncol., October 20, 2007; 25(30): 4806 - 4812. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X. Q. Lun, H. Zhou, T. Alain, B. Sun, L. Wang, J. W. Barrett, M. M. Stanford, G. McFadden, J. Bell, D. L. Senger, et al. Targeting Human Medulloblastoma: Oncolytic Virotherapy with Myxoma Virus Is Enhanced by Rapamycin Cancer Res., September 15, 2007; 67(18): 8818 - 8827. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Marimpietri, C. Brignole, B. Nico, F. Pastorino, A. Pezzolo, F. Piccardi, M. Cilli, D. Di Paolo, G. Pagnan, L. Longo, et al. Combined Therapeutic Effects of Vinblastine and Rapamycin on Human Neuroblastoma Growth, Apoptosis, and Angiogenesis Clin. Cancer Res., July 1, 2007; 13(13): 3977 - 3988. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. L. Martin and R. C. Baxter Expression of Insulin-Like Growth Factor Binding Protein-2 by MCF-7 Breast Cancer Cells Is Regulated through the Phosphatidylinositol 3-Kinase/AKT/Mammalian Target of Rapamycin Pathway Endocrinology, May 1, 2007; 148(5): 2532 - 2541. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Q. Wu, K. Kiguchi, T. Kawamoto, T. Ajiki, J. Traag, S. Carbajal, L. Ruffino, H. Thames, I. Wistuba, M. Thomas, et al. Therapeutic Effect of Rapamycin on Gallbladder Cancer in a Transgenic Mouse Model Cancer Res., April 15, 2007; 67(8): 3794 - 3800. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Hidalgo, J. C. Buckner, C. Erlichman, M. S. Pollack, J. P. Boni, G. Dukart, B. Marshall, L. Speicher, L. Moore, and E. K. Rowinsky A Phase I and Pharmacokinetic Study of Temsirolimus (CCI-779) Administered Intravenously Daily for 5 Days Every 2 Weeks to Patients with Advanced Cancer. Clin. Cancer Res., October 1, 2006; 12(19): 5755 - 5763. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. I. Fomchenko and E. C. Holland Mouse models of brain tumors and their applications in preclinical trials. Clin. Cancer Res., September 15, 2006; 12(18): 5288 - 5297. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Granville, R. M. Memmott, J. J. Gills, and P. A. Dennis Handicapping the Race to Develop Inhibitors of the Phosphoinositide 3-Kinase/Akt/Mammalian Target of Rapamycin Pathway Clin. Cancer Res., February 1, 2006; 12(3): 679 - 689. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Avellino, S. Romano, R. Parasole, R. Bisogni, A. Lamberti, V. Poggi, S. Venuta, and M. F. Romano Rapamycin stimulates apoptosis of childhood acute lymphoblastic leukemia cells Blood, August 15, 2005; 106(4): 1400 - 1406. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Chan, M. E. Scheulen, S. Johnston, K. Mross, F. Cardoso, C. Dittrich, W. Eiermann, D. Hess, R. Morant, V. Semiglazov, et al. Phase II Study of Temsirolimus (CCI-779), a Novel Inhibitor of mTOR, in Heavily Pretreated Patients With Locally Advanced or Metastatic Breast Cancer J. Clin. Oncol., August 10, 2005; 23(23): 5314 - 5322. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Boulay, J. Rudloff, J. Ye, S. Zumstein-Mecker, T. O'Reilly, D. B. Evans, S. Chen, and H. A. Lane Dual Inhibition of mTOR and Estrogen Receptor Signaling In vitro Induces Cell Death in Models of Breast Cancer Clin. Cancer Res., July 15, 2005; 11(14): 5319 - 5328. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. M. Ghobrial, T. E. Witzig, and A. A. Adjei Targeting Apoptosis Pathways in Cancer Therapy CA Cancer J Clin, May 1, 2005; 55(3): 178 - 194. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Wu, D. C. Birle, and I. F. Tannock Effects of the Mammalian Target of Rapamycin Inhibitor CCI-779 Used Alone or with Chemotherapy on Human Prostate Cancer Cells and Xenografts Cancer Res., April 1, 2005; 65(7): 2825 - 2831. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Vignot, S. Faivre, D. Aguirre, and E. Raymond mTOR-targeted therapy of cancer with rapamycin derivatives Ann. Onc., April 1, 2005; 16(4): 525 - 537. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Hahn, W. Li, C. Yu, M. Rahmani, P. Dent, and S. Grant Rapamycin and UCN-01 synergistically induce apoptosis in human leukemia cells through a process that is regulated by the Raf-1/MEK/ERK, Akt, and JNK signal transduction pathways Mol. Cancer Ther., March 1, 2005; 4(3): 457 - 470. [Abstract] [Full Text] [PDF]
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R. K. Goudar, Q. Shi, M. D. Hjelmeland, S. T. Keir, R. E. McLendon, C. J. Wikstrand, E. D. Reese, C. A. Conrad, P. Traxler, H. A. Lane, et al. Combination therapy of inhibitors of epidermal growth factor receptor/vascular endothelial growth factor receptor 2 (AEE788) and the mammalian target of rapamycin (RAD001) offers improved glioblastoma tumor growth inhibition Mol. Cancer Ther., January 1, 2005; 4(1): 101 - 112. [Abstract] [Full Text] [PDF]
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P. Frost, F. Moatamed, B. Hoang, Y. Shi, J. Gera, H. Yan, P. Frost, J. Gibbons, and A. Lichtenstein In vivo antitumor effects of the mTOR inhibitor CCI-779 against human multiple myeloma cells in a xenograft model Blood, December 15, 2004; 104(13): 4181 - 4187. [Abstract] [Full Text] [PDF]
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W. H. Mondesire, W. Jian, H. Zhang, J. Ensor, M.-C. Hung, G. B. Mills, and F. Meric-Bernstam Targeting Mammalian Target of Rapamycin Synergistically Enhances Chemotherapy-Induced Cytotoxicity in Breast Cancer Cells Clin. Cancer Res., October 15, 2004; 10(20): 7031 - 7042. [Abstract] [Full Text] [PDF]
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J. P. Dutcher Mammalian Target of Rapamycin Inhibition Clin. Cancer Res., September 15, 2004; 10(18): 6382S - 6387S. [Abstract] [Full Text] [PDF]
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C.-A. O. Nathan, N. Amirghahari, F. Abreo, X. Rong, G. Caldito, M. L. Jones, H. Zhou, M. Smith, D. Kimberly, and J. Glass Overexpressed eIF4E Is Functionally Active in Surgical Margins of Head and Neck Cancer Patients via Activation of the Akt/Mammalian Target of Rapamycin Pathway Clin. Cancer Res., September 1, 2004; 10(17): 5820 - 5827. [Abstract] [Full Text] [PDF]
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E. Raymond, J. Alexandre, S. Faivre, K. Vera, E. Materman, J. Boni, C. Leister, J. Korth-Bradley, A. Hanauske, and J.-P. Armand Safety and Pharmacokinetics of Escalated Doses of Weekly Intravenous Infusion of CCI-779, a Novel mTOR Inhibitor, in Patients With Cancer J. Clin. Oncol., June 15, 2004; 22(12): 2336 - 2347. [Abstract] [Full Text] [PDF]
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W.-C. Noh, W. H. Mondesire, J. Peng, W. Jian, H. Zhang, J. Dong, G. B. Mills, M.-C. Hung, and F. Meric-Bernstam Determinants of Rapamycin Sensitivity in Breast Cancer Cells Clin. Cancer Res., February 1, 2004; 10(3): 1013 - 1023. [Abstract] [Full Text] [PDF]
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A. Boulay, S. Zumstein-Mecker, C. Stephan, I. Beuvink, F. Zilbermann, R. Haller, S. Tobler, C. Heusser, T. O'Reilly, B. Stolz, et al. Antitumor Efficacy of Intermittent Treatment Schedules with the Rapamycin Derivative RAD001 Correlates with Prolonged Inactivation of Ribosomal Protein S6 Kinase 1 in Peripheral Blood Mononuclear Cells Cancer Res., January 1, 2004; 64(1): 252 - 261. [Abstract] [Full Text] [PDF]
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 M. Braga-Basaria and M. D. Ringel Beyond Radioiodine: A Review of Potential New Therapeutic Approaches for Thyroid Cancer J. Clin. Endocrinol. Metab., May 1, 2003; 88(5): 1947 - 1960. [Abstract] [Full Text] [PDF]
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T. Decker, S. Hipp, I. Ringshausen, C. Bogner, M. Oelsner, F. Schneller, and C. Peschel Rapamycin-induced G1 arrest in cycling B-CLL cells is associated with reduced expression of cyclin D3, cyclin E, cyclin A, and survivin Blood, January 1, 2003; 101(1): 278 - 285. [Abstract] [Full Text] [PDF]
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 B. K. Law, A. Chytil, N. Dumont, E. G. Hamilton, M. E. Waltner-Law, M. E. Aakre, C. Covington, and H. L. Moses Rapamycin Potentiates Transforming Growth Factor {beta}-Induced Growth Arrest in Nontransformed, Oncogene-Transformed, and Human Cancer Cells Mol. Cell. Biol., December 1, 2002; 22(23): 8184 - 8198. [Abstract] [Full Text] [PDF]
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Y. Shi, J. Gera, L. Hu, J.-h. Hsu, R. Bookstein, W. Li, and A. Lichtenstein Enhanced Sensitivity of Multiple Myeloma Cells Containing PTEN Mutations to CCI-779 Cancer Res., September 1, 2002; 62(17): 5027 - 5034. [Abstract] [Full Text] [PDF]
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F. Meric and K. K. Hunt Translation Initiation in Cancer: A Novel Target for Therapy Mol. Cancer Ther., September 1, 2002; 1(11): 971 - 979. [Abstract] [Full Text] [PDF]
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 C. B. Knobbe, A. Merlo, and G. Reifenberger Pten signaling in gliomas Neuro-oncol, July 1, 2002; 4(3): 196 - 211. [Abstract] [PDF]
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 Y. Shi, J.-h. Hsu, L. Hu, J. Gera, and A. Lichtenstein Signal Pathways Involved in Activation of p70S6K and Phosphorylation of 4E-BP1 following Exposure of Multiple Myeloma Tumor Cells to Interleukin-6 J. Biol. Chem., May 3, 2002; 277(18): 15712 - 15720. [Abstract] [Full Text] [PDF]
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 G. B. Mills, Y. Lu, and E. C. Kohn Linking molecular therapeutics to molecular diagnostics: Inhibition of the FRAP/RAFT/TOR component of the PI3K pathway preferentially blocks PTEN mutant cells in vitro and in vivo PNAS, August 28, 2001; 98(18): 10031 - 10033. [Full Text] [PDF]
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),
with cisplatin and rapamycin 0.001 ng/ml (
), rapamycin 0.01 ng/ml
(
), rapamycin 0.1 ng/ml (
), or rapamycin 1 ng/ml (•).
Simultaneous treatment of DAOY cells with cisplatin and rapamycin
increases cytotoxic activity in a dose-dependent and additive fashion.
Data are presented as the mean of five values. Bars, SE.
C, dose-response curves of rapamycin and camptothecin.
Fractional survival of DAOY cells incubated with CPT alone (
