Caspase-8 gene therapy using the human telomerase reverse transcriptase promoter for malignant glioma cells.
Telomerase is a distinctive candidate for targeted gene therapy of malignant gliomas, because the vast majority of malignant gliomas express telomerase activity while normal brain tissues do not. Recently, we developed a telomerase-specific expression system of caspase-8 gene using the promoter of the human telomerase reverse transcriptase (hTERT) gene. However, the transcriptional activity of hTERT-181 promoter (a 181-base pair [bp] region upstream of the transcription start site) was relatively lower in malignant glioma cells than in other tumors such as prostate cancer cells. To establish the hTERT/caspase-8 construct as a novel therapy for malignant gliomas, we need to increase the transcriptional activity of the hTERT promoter in malignant glioma cells. In the present study, we demonstrate that the transcriptional activity of hTERT-378 promoter (a 378-bp region) was 2- to 40-fold higher in hTERT-positive malignant glioma cells (A172, GB-1, T98G, U87-MG, U251-MG, and U373-MG) than that of hTERT-181. We further demonstrate that by using the hTERT-378/caspase-8 construct, apoptosis was restricted to malignant glioma cells, and was not seen in astrocytes or fibroblasts lacking hTERT. Moreover, the growth of subcutaneously established U373-MG tumors in mice was significantly inhibited by seven daily intratumoral injections of hTERT-378/caspase-8 construct and its inhibitory effect persisted during 3 additional weeks without additional treatment. These results suggest that the telomerase-specific expression of caspase-8 under hTERT-378 promoter is a novel targeting approach for the treatment of telomerase-positive malignant gliomas.
Komata
Tadashi
T
The Center for Surgery Research and Department of Neurosurgery, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Kondo
Yasuko
Y
Kanzawa
Takao
T
Ito
Hideaki
H
Hirohata
Satoshi
S
Koga
Shoji
S
Sumiyoshi
Hideaki
H
Takakura
Masahiro
M
Inoue
Masaki
M
Barna
Barbara P
BP
Germano
Isabelle M
IM
Kyo
Satoru
S
Kondo
Seiji
S
D000818:Animals; D017209:Apoptosis; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D005260:Female; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D005910:Glioma / Q000201:enzymology / Q000235:genetics / Q000628:therapy*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D019098:Telomerase; C505530:CASP8 protein, human; C506433:CASP9 protein, human; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases