Enhanced expression of the human vacuolar H+-ATPase c subunit gene (ATP6L) in response to anticancer agents.
We have isolated two overlapping genomic clones that contain the 5'-terminal portion of the human vacuolar H(+)-ATPase c subunit (ATP6L) gene. The sequence preceding the transcription initiation site, which is GC-rich, contains four GC boxes and one Oct1-binding site, but there is no TATA box or CCAAT box. In vivo footprint analysis in human cancer cells shows that two GC boxes and the Oct1-binding site are occupied by Sp1 and Oct1, respectively. We show here that treatment with anticancer agents enhances ATP6L expression. Although cisplatin did not induce ATP6L promoter activity, it altered ATP6L mRNA stability. On the other hand, the DNA topoisomerase II inhibitor, TAS-103, strongly induced promoter activity, and this effect was completely eradicated when a mutation was introduced into the Oct1-binding site. Treatment with TAS-103 increased the levels of both Sp1/Sp3 and Oct1 in nuclear extracts. Cooperative binding of Sp1 and Oct1 to the promoter is required for promoter activation by TAS-103. Incubation of a labeled oligonucleotide probe encompassing the -73/-68 GC box and -64/-57 Oct1-binding site with a nuclear extract from drug-treated KB cells yielded higher levels of the specific DNA-protein complex than an extract of untreated cells. Thus, the two transcription factors, Sp1 and Oct1 interact, in an adaptive response to DNA damage, by up-regulating expression of the vacuolar H(+)-ATPase genes. Furthermore, combination of the vacuolar H(+)-ATPase (V-ATPase) inhibitor, bafilomycin A1, with TAS-103 enhanced apoptosis of KB cells with an associated increase in caspase-3 activity. Our data suggest that the induction of V-ATPase expression is an anti-apoptotic defense, and V-ATPase inhibitors in combination with low-dose anticancer agents may provide a new therapeutic approach.
Department of Molecular Biology, University of Occupational and Environmental Health, School of Medicine, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
Takayuki
T
Torigoe
Hiroto
H
Izumi
Hiroshi
H
Ishiguchi
Hidetaka
H
Uramoto
Tadashi
T
Murakami
Tomoko
T
Ise
Yoichiro
Y
Yoshida
Mizuho
M
Tanabe
Minoru
M
Nomoto
Hideaki
H
Itoh
Kimitoshi
K
Kohno
D000251:Adenosine Triphosphatases / Q000096:biosynthesis* / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D053938:DNA Fragmentation; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017353:Gene Deletion; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D018942:Macrolides; D025261:Mitochondrial Proton-Translocating ATPases; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D027702:Organic Cation Transporter 1 / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism; D051705:Sp3 Transcription Factor; D013997:Time Factors; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism
D000900:Anti-Bacterial Agents; D000970:Antineoplastic Agents; D002843:Chromatin; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C501005:MT-ATP6 protein, human; D018942:Macrolides; D027702:Organic Cation Transporter 1; D012333:RNA, Messenger; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; C040929:bafilomycin A1; D004247:DNA; D008156:Luciferases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D000251:Adenosine Triphosphatases; D025262:Vacuolar Proton-Translocating ATPases; D025261:Mitochondrial Proton-Translocating ATPases; D002945:Cisplatin