MDM2 is a potential therapeutic target and prognostic factor for ovarian clear cell carcinomas with wild type TP53

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Abstract

MDM2, a ubiquitin ligase, suppresses wild type TP53 via proteasome-mediated degradation. We evaluated the prognostic and therapeutic value of MDM2 in ovarian clear cell carcinoma. MDM2 expression in ovarian cancer tissues was analyzed by microarray and real-time PCR, and its relationship with prognosis was evaluated by Kaplan-Meier method and log-rank test. The anti-tumor activities of MDM2 siRNA and the MDM2 inhibitor RG7112 were assessed by cell viability assay, western blotting, and flow cytometry. The anti-tumor effects of RG7112 in vivo were examined in a mouse xenograft model. MDM2 expression was significantly higher in clear cell carcinoma than in ovarian high-grade serous carcinoma ( P = 0.0092) and normal tissues ( P = 0.035). High MDM2 expression determined by microarray was significantly associated with poor progression-free survival and poor overall survival ( P = 0.0002, and P = 0.0008, respectively). Notably, RG7112 significantly suppressed cell viability in clear cell carcinoma cell lines with wild type TP53. RG7112 also strongly induced apoptosis, increased TP53 phosphorylation, and stimulated expression of the proapoptotic protein PUMA. Similarly, siRNA knockdown of MDM2 induced apoptosis. Finally, RG7112 significantly reduced the tumor volume of xenografted RMG-I clear cell carcinoma cells ( P = 0.033), and the density of microvessels ( P = 0.011). Our results highlight the prognostic value of MDM2 expression in clear cell carcinoma. Thus, MDM2 inhibitors such as RG7112 may constitute a class of potential therapeutics.

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Mutant p53 in Cancer: New Functions and Therapeutic Opportunities

Patricia A.J. Muller, Karen H. Vousden (2014)

Many different types of cancer show a high incidence of TP53 mutations, leading to the expression of mutant p53 proteins. There is growing evidence that these mutant p53s have both lost wild-type p53 tumor suppressor activity and gained functions that help to contribute to malignant progression. Understanding the functions of mutant p53 will help in the development of new therapeutic approaches that may be useful in a broad range of cancer types.

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Carcinoma of the ovary. FIGO 26th Annual Report on the Results of Treatment in Gynecological Cancer.

P Maisonneuve, F E Odicino, Andrew Quinn … (2006)

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Effect of the MDM2 antagonist RG7112 on the P53 pathway in patients with MDM2-amplified, well-differentiated or dedifferentiated liposarcoma: an exploratory proof-of-mechanism study.

Isabelle Ray-Coquard, Jean-Yves Blay, Antoine Italiano … (2012)

We report a proof-of-mechanism study of RG7112, a small-molecule MDM2 antagonist, in patients with chemotherapy-naive primary or relapsed well-differentiated or dedifferentiated MDM2-amplified liposarcoma who were eligible for resection. Patients with well-differentiated or dedifferentiated liposarcoma were enrolled at four centres in France. Patients received up to three 28-day neoadjuvant treatment cycles of RG7112 1440 mg/m(2) per day for 10 days. If a patient progressed at any point after the first cycle, the lesion was resected or, if unresectable, an end-of-study biopsy was done. The primary endpoint was to assess markers of RG7112-dependent MDM2 inhibition and P53 pathway activation (P53, P21, MDM2, Ki-67, macrophage inhibitory cytokine-1 [MIC-1], and apoptosis). All analyses were per protocol. This trial is registered with EudraCT, number 2009-015522-10. Between June 3, and Dec 14, 2010, 20 patients were enrolled and completed pretreatment and day 8 biopsies. 18 of 20 patients had TP53 wild-type tumours and two carried missense TP53 mutations. 14 of 17 assessed patients had MDM2 gene amplification. Compared with baseline, P53 and P21 concentrations, assessed by immunohistochemistry, had increased by a median of 4·86 times (IQR 4·38-7·97; p=0·0001) and 3·48 times (2·05-4·09; p=0·0001), respectively, at day 8 (give or take 2 days). At the same timepoint, relative MDM2 mRNA expression had increased by a median of 3·03 times (1·23-4·93; p=0·003) that at baseline. The median change from baseline for Ki-67-positive tumour cells was -5·05% (IQR -12·55 to 0·05; p=0·01). Drug exposure correlated with blood concentrations of MIC-1 (p<0·0001) and haematological toxicity. One patient had a confirmed partial response and 14 had stable disease. All patients experienced at least one adverse event, mostly nausea (14 patients), vomiting (11 patients), asthenia (nine patients), diarrhoea (nine patients), and thrombocytopenia (eight patients). There were 12 serious adverse events in eight patients, the most common of which were neutropenia (six patients) and thrombocytopenia (three patients). MDM2 inhibition activates the P53 pathway and decreases cell proliferation in MDM2-amplified liposarcoma. This study suggests that it is feasible to undertake neoadjuvant biopsy-driven biomarker studies in liposarcoma. F Hoffmann-La Roche. Copyright © 2012 Elsevier Ltd. All rights reserved.

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Author and article information

Journal

Journal ID (nlm-ta): Oncotarget

Journal ID (iso-abbrev): Oncotarget

Journal ID (publisher-id): Oncotarget

Journal ID (publisher-id): ImpactJ

Title: Oncotarget

Publisher: Impact Journals LLC

ISSN (Electronic): 1949-2553

Publication date Collection: 15 November 2016

Publication date (Electronic): 21 September 2016

Volume: 7

Issue: 46

Pages: 75328-75338

Affiliations

¹ Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan

² Department of Gynecologic Oncology, Saitama Medical University International Medical Center, Saitama, Japan

³ Division of Genome Science, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan

⁴ Department of Obstetrics and Gynecology, National Center for Global Health and Medicine, Tokyo, Japan

Author notes

Correspondence to: Katsutoshi Oda, katsutoshi-tky@ 123456umin.ac.jp

Article

Publisher ID: 12175

DOI: 10.18632/oncotarget.12175

PMC ID: 5342744

PubMed ID: 27659536

SO-VID: 4ae14913-28a3-4367-93a2-4b2c2fdee71e

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Date received : 14 May 2016

Date accepted : 2 September 2016

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