Antitumor activity of the selective MDM2 antagonist nutlin-3 against chemoresistant neuroblastoma with wild-type p53.
BACKGROUND
Restoring p53 function by antagonizing its interaction with the negative regulator MDM2 is an appealing nongenotoxic approach to treating tumors with wild-type p53. Mutational inactivation of p53 is rare in neuroblastoma tumors at diagnosis and occurs in only a subset of multidrug-resistant neuroblastomas.


METHODS
The antiproliferative and cytotoxic effect of nutlin-3, a small-molecule MDM2 antagonist, was examined in chemosensitive (UKF-NB-3) and matched chemoresistant neuroblastoma cells with wild-type p53 (UKF-NB-3(r)DOX20) or with mutant p53 (UKF-NB-3(r)VCR10). Activation of the p53 pathway was assessed by expression analysis of p53 target genes, flow cytometric cell cycle analysis, and apoptosis assays. Mice with established chemoresistant tumor xenografts were treated orally with nutlin-3 or vehicle control (n = 5-10 mice per group) and were used to evaluate effects on tumor growth, p53 pathway activity, and metastatic tumor burden. All statistical tests were two-sided.


RESULTS
Nutlin-3 induced a similar activation of the p53 pathway in UKF-NB-3 and UKF-NB-3(r)DOX20 cells, as evidenced by increased expression of p53 target genes, G1 cell cycle arrest, and induction of apoptosis. No such response was observed in UKF-NB-3(r)VCR10 cells with mutant p53. Oral administration of nutlin-3 to UKF-NB-3(r)DOX20 xenograft-bearing mice led to inhibition of primary tumor growth (mean tumor volume after 3 weeks of treatment, nutlin-3- vs vehicle-treated mice: 772 vs 1661 mm3, difference = 890 mm3, 95% confidence interval = 469 to 1311 mm3, P < .001), p53 pathway activation, and reduction in the extent of metastatic disease. The growth of UKF-NB-3(r)VCR10 xenografts was unaffected by nutlin-3.


CONCLUSIONS
Nutlin-3 activates the p53 pathway and suppresses tumor growth in this model system of chemoresistant neuroblastoma, provided that wild-type p53 is present.
Van Maerken
Tom
T
Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium. tom.vanmaerken@ugent.be
Ferdinande
Liesbeth
L
Taildeman
Jasmien
J
Lambertz
Irina
I
Yigit
Nurten
N
Vercruysse
Liesbeth
L
Rihani
Ali
A
Michaelis
Martin
M
Cinatl
Jindrich
J
Cuvelier
Claude A
CA
Marine
Jean-Christophe
JC
De Paepe
Anne
A
Bracke
Marc
M
Speleman
Frank
F
Vandesompele
Jo
J
D000284:Administration, Oral; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D053938:DNA Fragmentation; D004171:Diploidy; D019008:Drug Resistance, Neoplasm; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D015151:Immunoblotting; D007150:Immunohistochemistry; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D009447:Neuroblastoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014183:Transplantation, Heterologous; D016159:Tumor Suppressor Protein p53 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
D000970:Antineoplastic Agents; D007093:Imidazoles; D010879:Piperazines; D016159:Tumor Suppressor Protein p53; C482205:nutlin 3; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C505409:Casp3 protein, mouse; D053148:Caspase 3; D053179:Caspase 7