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Requirement for human Mps1/TTK in oxidative DNA damage repair and cell survival through MDM2 phosphorylation.

ABSTRACT: Human Mps1 (hMps1) is a protein kinase essential for mitotic checkpoints and the DNA damage response. Here, we present new evidence that hMps1 also participates in the repair of oxidative DNA lesions and cell survival through the MDM2-H2B axis. In response to oxidative stress, hMps1 phosphorylates MDM2, which in turn promotes histone H2B ubiquitination and chromatin decompaction. These events facilitate oxidative DNA damage repair and ATR-CHK1, but not ATM-CHK2 signaling. Depletion of hMps1 or MDM2 compromised H2B ubiquitination, DNA repair and cell survival. The impairment could be rescued by re-expression of WT but not the phospho-deficient MDM2 mutant, supporting the involvement of hMps1-dependent MDM2 phosphorylation in the oxidative stress response. In line with these findings, localization of RPA and base excision repair proteins to damage foci also requires MDM2 and hMps1. Significantly, like MDM2, hMps1 is upregulated in human sarcoma, suggesting high hMps1 and MDM2 expression may be beneficial for tumors constantly challenged by an oxidative micro-environment. Our study therefore identified an hMps1-MDM2-H2B signaling axis that likely plays a relevant role in tumor progression.

SUBMITTER: Yu ZC

PROVIDER: S-EPMC4756815 | biostudies-other | 2016 Feb

REPOSITORIES: biostudies-other

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Requirement for human Mps1/TTK in oxidative DNA damage repair and cell survival through MDM2 phosphorylation.

Yu Zheng-Cheng ZC Huang Yi-Fu YF Shieh Sheau-Yann SY

Nucleic acids research 20151103 3

Human Mps1 (hMps1) is a protein kinase essential for mitotic checkpoints and the DNA damage response. Here, we present new evidence that hMps1 also participates in the repair of oxidative DNA lesions and cell survival through the MDM2-H2B axis. In response to oxidative stress, hMps1 phosphorylates MDM2, which in turn promotes histone H2B ubiquitination and chromatin decompaction. These events facilitate oxidative DNA damage repair and ATR-CHK1, but not ATM-CHK2 signaling. Depletion of hMps1 or M ...[more]

PMID: 26531827

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Project description:Inorganic arsenic is an environmental carcinogen that may act through multiple mechanisms including formation of methylated derivatives in vivo. Sodium arsenite (up to 5.0 microM) renders arsenic methylation-competent TRL1215 rat liver epithelial cells tumorigenic in nude mice at 18 weeks of exposure and arsenic methylation-deficient RWPE-1 human prostate epithelial cells tumorigenic at 30 weeks of exposure. We assessed the role of arsenic biomethylation in oxidative DNA damage (ODD) using a recently developed immuno-spin trapping method.Immuno-spin trapping was used to measure ODD after chronic exposure of cultured TRL1215 vs RWPE-1 cells, or of methylation-competent UROtsa/F35 vs methylation-deficient UROtsa human urothelial cells, to sodium arsenite. Secreted matrix metalloproteinase (MMP)-2 and -9 activity, as analyzed by zymography, cellular invasiveness by using a transwell assay, and colony formation by using soft agar assay were compared in cells exposed to arsenite with and without selenite, an arsenic biomethylation inhibitor, to assess the role of ODD in the transition to an in vitro cancer phenotype.Exposure of methylation-competent TRL1215 cells to up to 1.0 microM sodium arsenite was followed by a substantial increase in ODD at 5-18 weeks (eg, at 16 weeks with 1.0 microM arsenite, 1138% of control, 95% confidence interval [CI] = 797% to 1481%), whereas exposure of methylation-deficient RWPE-1 cells to up to 5.0 microM arsenite did not increase ODD for a 30-week period. Inhibition of arsenic biomethylation with sodium selenite abolished arsenic-induced ODD and invasiveness, colony formation, and MMP-2 and -9 hypersecretion in TRL1215 cells. Arsenic induced ODD in methylation-competent UROtsa/F35 cells (eg, at 16 weeks, with 1.0 microM arsenite 225% of control, 95% CI = 188% to 262%) but not in arsenic methylation-deficient UROtsa cells, and ODD levels corresponded to the levels of increased invasiveness, colony formation, and hypersecretion of active MMP-2 and -9 seen after transformation to an in vitro cancer phenotype.Arsenic biomethylation appears to be obligatory for arsenic-induced ODD and appears linked in some cells with the accelerated transition to an in vitro cancer phenotype.

Project description:The Cut homeobox 1 (CUX1) gene is a target of loss-of-heterozygosity in many cancers, yet elevated CUX1 expression is frequently observed and is associated with shorter disease-free survival. The dual role of CUX1 in cancer is illustrated by the fact that most cell lines with CUX1 LOH display amplification of the remaining allele, suggesting that decreased CUX1 expression facilitates tumor development while increased CUX1 expression is needed in tumorigenic cells. Indeed, CUX1 was found in a genome-wide RNAi screen to identify synthetic lethal interactions with oncogenic RAS. Here we show that CUX1 functions in base excision repair as an ancillary factor for the 8-oxoG-DNA glycosylase, OGG1. Single cell gel electrophoresis (comet assay) reveals that Cux1?/? MEFs are haploinsufficient for the repair of oxidative DNA damage, whereas elevated CUX1 levels accelerate DNA repair. In vitro base excision repair assays with purified components demonstrate that CUX1 directly stimulates OGG1's enzymatic activity. Elevated reactive oxygen species (ROS) levels in cells with sustained RAS pathway activation can cause cellular senescence. We show that elevated expression of either CUX1 or OGG1 prevents RAS-induced senescence in primary cells, and that CUX1 knockdown is synthetic lethal with oncogenic RAS in human cancer cells. Elevated CUX1 expression in a transgenic mouse model enables the emergence of mammary tumors with spontaneous activating Kras mutations. We confirmed cooperation between Kras(G12V) and CUX1 in a lung tumor model. Cancer cells can overcome the antiproliferative effects of excessive DNA damage by inactivating a DNA damage response pathway such as ATM or p53 signaling. Our findings reveal an alternate mechanism to allow sustained proliferation in RAS-transformed cells through increased DNA base excision repair capability. The heightened dependency of RAS-transformed cells on base excision repair may provide a therapeutic window that could be exploited with drugs that specifically target this pathway.

Dataset Information

Requirement for human Mps1/TTK in oxidative DNA damage repair and cell survival through MDM2 phosphorylation.

Publications

Requirement for human Mps1/TTK in oxidative DNA damage repair and cell survival through MDM2 phosphorylation.

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