• Open Access

Potent in vitro and in vivo antitumor effects of MDM2 inhibitor nutlin-3 in gastric cancer cells

Authors

  • Shinji Endo,

    1. Department of Gastroenterology and Hepatology, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba
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  • Kenji Yamato,

    1. Section of Bacterial Pathogenesis, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Tokyo, Japan
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  • Sachiko Hirai,

    1. Department of Gastroenterology and Hepatology, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba
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  • Toshikazu Moriwaki,

    1. Department of Gastroenterology and Hepatology, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba
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  • Kuniaki Fukuda,

    1. Department of Gastroenterology and Hepatology, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba
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  • Hideo Suzuki,

    1. Department of Gastroenterology and Hepatology, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba
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  • Masato Abei,

    1. Department of Gastroenterology and Hepatology, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba
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  • Ichiro Nakagawa,

    1. Section of Bacterial Pathogenesis, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Tokyo, Japan
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  • Ichinosuke Hyodo

    Corresponding author
    1. Department of Gastroenterology and Hepatology, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba
      3To whom correspondence should be addressed. E-mail: ihyodo@md.tsukuba.ac.jp
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3To whom correspondence should be addressed. E-mail: ihyodo@md.tsukuba.ac.jp

Abstract

The tumor suppressor gene p53 is the most frequently mutated gene in human cancers. However, its mutation rate is relatively low in gastric cancer compared with other cancers. In this study, we investigated the mechanisms underlying the antitumor effects of nutlin-3, an inhibitor of human homolog of murine double minute 2 (MDM2). MDM2 is a negative regulator of p53. Four gastric cancer cell lines with wild-type p53 (wt p53) and three with mutant-type p53 (mt p53) were analyzed for MDM2 and MDM4 expression by immunoblotting, and for their gene amplification by quantitative real-time PCR. Moreover, the viability of cells exposed to nutlin-3 was examined by WST-8 assay, and the expression of p53 and its downstream genes was analyzed by immunoblotting. Nutlin-3 stabilized p53 and increased the expression of p21WAF1 and Noxa, and cleaved poly (ADP)-ribose polymerase regardless of the pre-expression levels of MDM2 and MDM4 in gastric cancer cells with wt p53. Flow cytometry revealed that nutlin-3 arrested the cell cycle in G1 phase and induced apoptosis in the cell lines. These nutlin-3 effects were not observed in the cell lines with mt p53. Nutlin-3 exerted additive or synergistic cytotoxicity in combination with 5-fluorouracil or cisplatin in most cell lines with wt p53. An in vivo antitumor effect of nutlin-3 alone and its additive augmentation by 5-fluorouracil were confirmed in an MDM2 overexpressed xenograft tumor model. Nutlin-3 showed potent antitumor activity against human gastric cancer cells with wt p53 and shows promise as a single agent and in combination with conventional anticancer drugs. (Cancer Sci 2011; 102: 605–613)

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