Transduction of Apaf-1 or caspase-9 induces apoptosis in A-172 cells that are resistant to p53-mediated apoptosis.
p53 replacement gene therapy has been carried out clinically for cancers with p53 mutations; however, some cancers are resistant to p53 gene therapy. In this study, we transduced A-172 and U251 cells harboring p53 mutations with wild-type p53 using adenovirus vectors to induce wild-type p53 protein at similar expression levels. A-172 cells did not undergo apoptosis after p53 transduction, whereas U251 cells were markedly sensitive to p53-mediated apoptosis. A-172 cells showed higher endogenous expression of Bcl-X(L) than U251, and transduction of Bcl-X(L) repressed p53-mediated apoptosis in U251 cells, suggesting that high endogenous expression of Bcl-X(L) renders A-172 cells, at least in part, resistant to p53-mediated apoptosis. We transduced A-172 cells and U251 cells with the Apaf-1 or caspase-9 genes; both are downstream components of p53-mediated apoptosis. We found that A-172 cells were highly sensitive to Apaf-1- and caspase-9-mediated apoptosis. The results indicate that A-172 cells harboring mutant p53 were not susceptible to p53-mediated apoptosis, possibly due to high endogenous expression of Bcl-X(L). Transduction of Apaf-1 or caspase-9 would override the resistance mechanism of apoptosis in A-172 cells. These findings provide potentially a novel approach in killing cancers that are resistant to p53 replacement gene therapy.
Shinoura
N
N
Department of Molecular Biotherapy Research, Cancer Chemotherapy Center, Cancer Institute, Tokyo, Japan.
Sakurai
S
S
Asai
A
A
Kirino
T
T
Hamada
H
H
D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis; D053477:Apoptotic Protease-Activating Factor 1; D015153:Blotting, Western; D053453:Caspase 9; D020169:Caspases / Q000235:genetics / Q000378:metabolism*; D053938:DNA Fragmentation; D005434:Flow Cytometry; D005910:Glioma / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D009154:Mutation / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051020:bcl-X Protein
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; C494811:BCL2L1 protein, human; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051020:bcl-X Protein; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases