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ATM Dependent DUSP6 Modulation of p53 Involved in Synergistic Targeting of MAPK and p53 Pathways with Trametinib and MDM2 Inhibitors in Cutaneous Melanoma

Lookup NU author(s): Dr Chiao-En Wu, Tsin Koay, Arman Esfandiari, Professor Penny Lovat, Professor John Lunec

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

MAPK and p14ARF⁻MDM2⁻p53 pathways are critical in cutaneous melanomas. Here, synergistic combination of the MEK inhibitor, trametinib, with MDM2 inhibitors, nutlin-3/RG7388/HDM201, and the mechanistic basis of responses, for BRAFV600E and p53WT melanoma cells, are reported. The combination treatments induced higher levels of p53 target gene transcripts and protein products, resulting in increased cell cycle arrest and apoptosis compared with MDM2 inhibitors alone, suggesting trametinib synergized with MDM2 inhibitors via upregulation of p53-dependent pathways. In addition, DUSP6 phosphatase involvement was indicated by downregulation of its mRNA and protein following pERK reduction by trametinib. Furthermore, suppression of DUSP6 by siRNA, or inhibition with the small molecule inhibitor, BCI, at a dose without cytotoxicity, potentiated the effect of MDM2 inhibitors through increased ATM-dependent p53 phosphorylation, as demonstrated by complete reversal with the ATM inhibitor, KU55933. Trametinib synergizes with MDM2 inhibitors through a novel DUSP6 mechanism in BRAFV600E and p53WT melanoma cells, in which DUSP6 regulation of p53 phosphorylation is mediated by ATM. This provides a new therapeutic rationale for combination treatments involving activation of the ATM/p53 pathway and MAPK pathway inhibition.


Publication metadata

Author(s): Wu CE, Koay TS, Esfandiari A, Ho YH, Lovat P, Lunec J

Publication type: Article

Publication status: Published

Journal: Cancers

Year: 2019

Volume: 11

Issue: 1

Online publication date: 20/12/2018

Acceptance date: 18/12/2018

Date deposited: 01/03/2019

ISSN (electronic): 2072-6694

Publisher: M D P I AG

URL: https://doi.org/10.3390/cancers11010003

DOI: 10.3390/cancers11010003


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