Irinotecan activates p53 with its active metabolite, resulting in human hepatocellular carcinoma apoptosis.
The topoisomerase I inhibitor irinotecan is widely used in anticancer therapy, although the detailed mechanism is still unclear. We investigated the apoptotic mechanisms of irinotecan in human hepatocellular carcinoma (HCC) cell lines (Huh7). SN-38 caused a significant decrease in cell proliferation and induced apoptosis in Huh7 cells and HepG2 cells. SN-38 significantly increased the expression of p53 protein and its phosphorylation at Ser(15) in the nucleus and apoptosis-inducing proteins Bax, caspase-9, and caspase-3, while it significantly decreased the antiapoptosis protein Bcl-xL of Huh7 cells. SN-38-induced apoptosis was recovered after p53 antisense oligodeoxynucleotide (AS ODN) pretreatment, while Huh7 cells were precultured with p53 AS ODN, followed by the addition of SN-38 for 24 h. Furthermore, increases in p53 DNA-binding activity were observed in the nuclei of Huh7 cells after SN-38 treatment as shown by electrophoretic mobility shift analysis. SN-38 binding motifs were detected in the proximal promoter of p53 (bases -433 to -317 and -814 to -711). These results suggest that the p53-mediated apoptosis pathway is important in the anticancer effects of irinotecan in hepatocellular carcinoma.
Takeba
Yuko
Y
Department of Pharmacology, St. Marianna University School of Medicine, 2-16-1, Sugao, Miyamae-ku, Kawasaski, Kanagawa 216-8511, Japan. yakuri@marianna-u.ac.jp
Kumai
Toshio
T
Matsumoto
Naoki
N
Nakaya
Sachiko
S
Tsuzuki
Yoshimitsu
Y
Yanagida
Yohei
Y
Kobayashi
Shinichi
S
D000972:Antineoplastic Agents, Phytogenic / Q000493:pharmacokinetics / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000502:physiology; D015153:Blotting, Western; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D015342:DNA Probes; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D020287:In Situ Nick-End Labeling; D000077146:Irinotecan; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000473:pathology; D009841:Oligonucleotides / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; D015342:DNA Probes; D009841:Oligonucleotides; D016159:Tumor Suppressor Protein p53; D000077146:Irinotecan; D002166:Camptothecin