DNA damage response (DDR) pathway protects cells from genome instability and prevents cancer development. Tumor suppressor p53 is a key molecule that interconnects DDR, cell cycle checkpoints, and cell fate decisions in the presence of genotoxic stress. Inactivating mutations in TP53 and other genes implicated in DDR potentiate cancer development and also influence the sensitivity of cancer cells to treatment. Protein phosphatase 2C delta (referred to as WIP1) is a negative regulator of DDR and has been proposed as potential pharmaceutical target. Until recently, exploitation of WIP1 inhibition for suppression of cancer cell growth was compromised by the lack of selective small-molecule inhibitors effective at cellular and organismal levels. Here, we review recent advances in development of WIP1 inhibitors and discuss their potential use in cancer treatment.
- MeSH
- konformace proteinů MeSH
- lidé MeSH
- nádorový supresorový protein p53 metabolismus MeSH
- nádory farmakoterapie metabolismus MeSH
- onkogeny MeSH
- poškození DNA MeSH
- proteinfosfatasa 2C antagonisté a inhibitory chemie imunologie metabolismus MeSH
- protinádorové látky farmakologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
PP2C family serine/threonine phosphatase WIP1 acts as a negative regulator of the tumor suppressor p53 and is implicated in silencing of cellular responses to genotoxic stress. Chromosomal locus 17q23 carrying the PPM1D (coding for WIP1) is commonly amplified in breast carcinomas and WIP1 was proposed as potential pharmacological target. Here we employed a cellular model with knocked out PPM1D to validate the specificity and efficiency of GSK2830371, novel small molecule inhibitor of WIP1. We have found that GSK2830371 increased activation of the DNA damage response pathway to a comparable level as the loss of PPM1D. In addition, GSK2830371 did not affect proliferation of cells lacking PPM1D but significantly supressed proliferation of breast cancer cells with amplified PPM1D. Over time cells treated with GSK2830371 accumulated in G1 and G2 phases of the cell cycle in a p21-dependent manner and were prone to induction of senescence by a low dose of MDM2 antagonist nutlin-3. In addition, combined treatment with GSK2830371 and doxorubicin or nutlin-3 potentiated cell death through a strong induction of p53 pathway and activation of caspase 9. We conclude that efficient inhibition of WIP1 by GSK2830371 sensitizes breast cancer cells with amplified PPM1D and wild type p53 to chemotherapy.
- MeSH
- aminopyridiny farmakologie MeSH
- apoptóza účinky léků MeSH
- buněčný cyklus účinky léků MeSH
- chemorezistence * MeSH
- dipeptidy farmakologie MeSH
- imidazoly farmakologie MeSH
- lidé MeSH
- nádorové buňky kultivované MeSH
- nádorový supresorový protein p53 metabolismus MeSH
- nádory prsu farmakoterapie enzymologie patologie MeSH
- piperaziny farmakologie MeSH
- poškození DNA účinky léků MeSH
- proliferace buněk účinky léků MeSH
- proteinfosfatasa 2C antagonisté a inhibitory genetika metabolismus MeSH
- protoonkogenní proteiny c-mdm2 antagonisté a inhibitory genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
The DNA damage response (DDR) pathway and its core component tumor suppressor p53 block cell cycle progression after genotoxic stress and represent an intrinsic barrier preventing cancer development. The serine/threonine phosphatase PPM1D/Wip1 inactivates p53 and promotes termination of the DDR pathway. Wip1 has been suggested to act as an oncogene in a subset of tumors that retain wild-type p53. In this paper, we have identified novel gain-of-function mutations in exon 6 of PPM1D that result in expression of C-terminally truncated Wip1. Remarkably, mutations in PPM1D are present not only in the tumors but also in other tissues of breast and colorectal cancer patients, indicating that they arise early in development or affect the germline. We show that mutations in PPM1D affect the DDR pathway and propose that they could predispose to cancer.
- MeSH
- buněčný cyklus MeSH
- G1 fáze * MeSH
- genetická predispozice k nemoci MeSH
- HeLa buňky MeSH
- lidé MeSH
- MFC-7 buňky MeSH
- mutace * MeSH
- nádorové buněčné linie MeSH
- nádorový supresorový protein p53 genetika MeSH
- nádory metabolismus MeSH
- poškození DNA MeSH
- proteinfosfatasy genetika fyziologie MeSH
- regulace genové exprese u nádorů * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Cells are constantly challenged by DNA damage and protect their genome integrity by activation of an evolutionary conserved DNA damage response pathway (DDR). A central core of DDR is composed of a spatiotemporally ordered net of post-translational modifications, among which protein phosphorylation plays a major role. Activation of checkpoint kinases ATM/ATR and Chk1/2 leads to a temporal arrest in cell cycle progression (checkpoint) and allows time for DNA repair. Following DNA repair, cells re-enter the cell cycle by checkpoint recovery. Wip1 phosphatase (also called PPM1D) dephosphorylates multiple proteins involved in DDR and is essential for timely termination of the DDR. Here we have investigated how Wip1 is regulated in the context of the cell cycle. We found that Wip1 activity is downregulated by several mechanisms during mitosis. Wip1 protein abundance increases from G(1) phase to G(2) and declines in mitosis. Decreased abundance of Wip1 during mitosis is caused by proteasomal degradation. In addition, Wip1 is phosphorylated at multiple residues during mitosis, and this leads to inhibition of its enzymatic activity. Importantly, ectopic expression of Wip1 reduced γH2AX staining in mitotic cells and decreased the number of 53BP1 nuclear bodies in G(1) cells. We propose that the combined decrease and inhibition of Wip1 in mitosis decreases the threshold necessary for DDR activation and enables cells to react adequately even to modest levels of DNA damage encountered during unperturbed mitotic progression.
- MeSH
- DNA primery genetika MeSH
- fluorescenční protilátková technika MeSH
- fosforylace MeSH
- hmotnostní spektrometrie MeSH
- kontrolní body M fáze buněčného cyklu fyziologie MeSH
- kvantitativní polymerázová řetězová reakce MeSH
- lidé MeSH
- malá interferující RNA genetika MeSH
- mitóza fyziologie MeSH
- nádorové buněčné linie MeSH
- poškození DNA * MeSH
- proteinfosfatasy metabolismus MeSH
- regulace genové exprese fyziologie MeSH
- signální transdukce fyziologie MeSH
- transfekce MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
169 s. : bibliogr.
