The transcription factor p53 is the most frequently impaired tumor suppressor in human cancers. In response to various stress stimuli, p53 activates transcription of genes that mediate its tumor-suppressive functions. Distinctive characteristics of p53 outlined here enable a well-defined program of genes involved in cell cycle arrest, apoptosis, senescence, differentiation, metabolism, autophagy, DNA repair, anti-viral response, and anti-metastatic functions, as well as facilitating autoregulation within the p53 network. This versatile, anti-cancer network governed chiefly by a single protein represents an immense opportunity for targeted cancer treatment, since about half of human tumors retain unmutated p53. During the last two decades, numerous compounds have been developed to block the interaction of p53 with the main negative regulator MDM2. However, small molecule inhibitors of MDM2 only induce a therapeutically desirable apoptotic response in a limited number of cancer types. Moreover, clinical trials of the MDM2 inhibitors as monotherapies have not met expectations and have revealed hematological toxicity as a characteristic adverse effect across this drug class. Currently, combination treatments are the leading strategy for enhancing efficacy and reducing adverse effects of MDM2 inhibitors. This review summarizes efforts to identify and test therapeutics that work synergistically with MDM2 inhibitors. Two main types of drugs have emerged among compounds used in the following combination treatments: first, modulators of the p53-regulated transcriptome (including chromatin modifiers), translatome, and proteome, and second, drugs targeting the downstream pathways such as apoptosis, cell cycle arrest, DNA repair, metabolic stress response, immune response, ferroptosis, and growth factor signaling. Here, we review the current literature in this field, while also highlighting overarching principles that could guide target selection in future combination treatments.

• Klíčová slova
• combination therapy, integrated stress response, nelfinavir, nutlin, p53, polytherapy,
• MeSH
• cílená molekulární terapie * MeSH
• lidé MeSH
• nádorový supresorový protein p53 * metabolismus   genetika   antagonisté a inhibitory   MeSH
• nádory * farmakoterapie   metabolismus   genetika   MeSH
• protinádorové látky * terapeutické užití   farmakologie   MeSH
• protoonkogenní proteiny c-mdm2 antagonisté a inhibitory   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• nádorový supresorový protein p53 * MeSH
• protinádorové látky * MeSH
• protoonkogenní proteiny c-mdm2 MeSH

Cell cycle checkpoints, oncogene-induced senescence and programmed cell death represent intrinsic barriers to tumorigenesis. Protein phosphatase magnesium-dependent 1 (PPM1D) is a negative regulator of the tumour suppressor p53 and has been implicated in termination of the DNA damage response. Here, we addressed the consequences of increased PPM1D activity resulting from the gain-of-function truncating mutations in exon 6 of the PPM1D. We show that while control cells permanently exit the cell cycle and reside in senescence in the presence of DNA damage caused by ionising radiation or replication stress induced by the active RAS oncogene, RPE1-hTERT and BJ-hTERT cells carrying the truncated PPM1D continue proliferation in the presence of DNA damage, form micronuclei and accumulate genomic rearrangements revealed by karyotyping. Further, we show that increased PPM1D activity promotes cell growth in the soft agar and formation of tumours in xenograft models. Finally, expression profiling of the transformed clones revealed dysregulation of several oncogenic and tumour suppressor pathways. Our data support the oncogenic potential of PPM1D in the context of exposure to ionising radiation and oncogene-induced replication stress.

• MeSH
• buněčná smrt genetika   MeSH
• lidé MeSH
• myši MeSH
• nádorová transformace buněk * genetika   MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• poškození DNA * genetika   MeSH
• proliferace buněk genetika   MeSH
• proteinfosfatasa 2C * genetika   metabolismus   MeSH
• proteinfosfatasy genetika   metabolismus   MeSH
• stárnutí buněk * genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• nádorový supresorový protein p53 MeSH
• PPM1D protein, human MeSH Prohlížeč
• proteinfosfatasa 2C * MeSH
• proteinfosfatasy MeSH

Oncogene-induced replication stress has been recognized as a major cause of genome instability in cancer cells. Increased expression of cyclin E1 caused by amplification of the CCNE1 gene is a common cause of replication stress in various cancers. Protein phosphatase magnesium-dependent 1 delta (PPM1D) is a negative regulator of p53 and has been implicated in termination of the cell cycle checkpoint. Amplification of the PPM1D gene or frameshift mutations in its final exon promote tumorigenesis. Here, we show that PPM1D activity further increases the replication stress caused by overexpression of cyclin E1. In particular, we demonstrate that cells expressing a truncated mutant of PPM1D progress faster from G1 to S phase and fail to complete licensing of the replication origins. In addition, we show that transcription-replication collisions and replication fork slowing caused by CCNE1 overexpression are exaggerated in cells expressing the truncated PPM1D. Finally, replication speed and accumulation of focal DNA copy number alterations caused by induction of CCNE1 expression was rescued by pharmacological inhibition of PPM1D. We propose that increased activity of PPM1D suppresses the checkpoint function of p53 and thus promotes genome instability in cells expressing the CCNE1 oncogene.

• Klíčová slova
• PPM1D phosphatase, cancer, cell cycle, cyclin E1, replication stress,
• MeSH
• cyklin E genetika   metabolismus   MeSH
• lidé MeSH
• nádorový supresorový protein p53 * genetika   metabolismus   MeSH
• nádory * MeSH
• nestabilita genomu MeSH
• proteinfosfatasa 2C genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cyklin E MeSH
• nádorový supresorový protein p53 * MeSH
• PPM1D protein, human MeSH Prohlížeč
• proteinfosfatasa 2C MeSH

Protein phosphatase magnesium-dependent 1 delta (PPM1D) terminates the cell cycle checkpoint by dephosphorylating the tumour suppressor protein p53. By targeting additional substrates at chromatin, PPM1D contributes to the control of DNA damage response and DNA repair. Using proximity biotinylation followed by proteomic analysis, we identified a novel interaction between PPM1D and the shelterin complex that protects telomeric DNA. In addition, confocal microscopy revealed that endogenous PPM1D localises at telomeres. Further, we found that ATR phosphorylated TRF2 at S410 after induction of DNA double strand breaks at telomeres and this modification increased after inhibition or loss of PPM1D. TRF2 phosphorylation stimulated its interaction with TIN2 both in vitro and at telomeres. Conversely, induced expression of PPM1D impaired localisation of TIN2 and TPP1 at telomeres. Finally, recruitment of the DNA repair factor 53BP1 to the telomeric breaks was strongly reduced after inhibition of PPM1D and was rescued by the expression of TRF2-S410A mutant. Our results suggest that TRF2 phosphorylation promotes the association of TIN2 within the shelterin complex and regulates DNA repair at telomeres.

• MeSH
• fosforylace MeSH
• lidé MeSH
• poškození DNA MeSH
• protein TRF2 * MeSH
• proteiny vázající telomery * metabolismus   MeSH
• proteomika MeSH
• shelterinový komplex * MeSH
• telomery metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• protein TRF2 * MeSH
• proteiny vázající telomery * MeSH
• shelterinový komplex * MeSH
• TINF2 protein, human MeSH Prohlížeč

Since the discovery of the first MDM2 inhibitors, we have gained deeper insights into the cellular roles of MDM2 and p53. In this review, we focus on MDM2 inhibitors that bind to the p53-binding domain of MDM2 and aim to disrupt the binding of MDM2 to p53. We describe the basic mechanism of action of these MDM2 inhibitors, such as nutlin-3a, summarise the determinants of sensitivity to MDM2 inhibition from p53-dependent and p53-independent points of view and discuss the problems with innate and acquired resistance to MDM2 inhibition. Despite progress in MDM2 inhibitor design and ongoing clinical trials, their broad use in cancer treatment is not fulfilling expectations in heterogenous human cancers. We assess the MDM2 inhibitor types in clinical trials and provide an overview of possible sources of resistance to MDM2 inhibition, underlining the need for patient stratification based on these aspects to gain better clinical responses, including the use of combination therapies for personalised medicine.

• Klíčová slova
• Combination therapy, MDM2, MDM2 inhibitor, Nutlin-3a, Personalised medicine, Resistance, p53,
• MeSH
• bakteriální léková rezistence účinky léků   fyziologie   MeSH
• cílená molekulární terapie metody   MeSH
• klinické zkoušky jako téma MeSH
• lidé MeSH
• nádorový supresorový protein p53 antagonisté a inhibitory   genetika   metabolismus   MeSH
• nádory farmakoterapie   MeSH
• protinádorové látky farmakologie   MeSH
• protoonkogenní proteiny c-mdm2 antagonisté a inhibitory   genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• MDM2 protein, human MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• protinádorové látky MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• TP53 protein, human MeSH Prohlížeč

Twelve novel analogs of STAT3 inhibitor BP-1-102 were designed and synthesised with the aim to modify hydrophobic fragments of the molecules that are important for interaction with the STAT3 SH2 domain. The cytotoxic activity of the reference and novel compounds was evaluated using several human and two mouse cancer cell lines. BP-1-102 and its two analogs emerged as effective cytotoxic agents and were further tested in additional six human and two murine cancer cell lines, in all of which they manifested the cytotoxic effect in a micromolar range. Reference compound S3I-201.1066 was found ineffective in all tested cell lines, in contrast to formerly published data. The ability of selected BP-1-102 analogs to induce apoptosis and inhibition of STAT3 receptor-mediated phosphorylation was confirmed. The structure-activity relationship confirmed a demand for two hydrophobic substituents, i.e. the pentafluorophenyl moiety and another spatially bulky moiety, for effective cytotoxic activity and STAT3 inhibition.

• Klíčová slova
• SH2 domain, STAT3 signalling pathway, cancer, inhibitor, structure–activity relationship,
• MeSH
• apoptóza účinky léků   MeSH
• fosforylace účinky léků   MeSH
• hydrofobní a hydrofilní interakce MeSH
• kultivované buňky MeSH
• kyseliny aminosalicylové chemická syntéza   chemie   farmakologie   MeSH
• lidé MeSH
• molekulární struktura MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• proliferace buněk účinky léků   MeSH
• protinádorové látky chemická syntéza   chemie   farmakologie   MeSH
• racionální návrh léčiv * MeSH
• sulfonamidy chemická syntéza   chemie   farmakologie   MeSH
• transkripční faktor STAT3 antagonisté a inhibitory   metabolismus   MeSH
• viabilita buněk účinky léků   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• BP-1-102 MeSH Prohlížeč
• kyseliny aminosalicylové MeSH
• protinádorové látky MeSH
• STAT3 protein, human MeSH Prohlížeč
• sulfonamidy MeSH
• transkripční faktor STAT3 MeSH

Cyclin A2 is a key regulator of the cell cycle, implicated both in DNA replication and mitotic entry. Cyclin A2 participates in feedback loops that activate mitotic kinases in G2 phase, but why active Cyclin A2-CDK2 during the S phase does not trigger mitotic kinase activation remains unclear. Here, we describe a change in localisation of Cyclin A2 from being only nuclear to both nuclear and cytoplasmic at the S/G2 border. We find that Cyclin A2-CDK2 can activate the mitotic kinase PLK1 through phosphorylation of Bora, and that only cytoplasmic Cyclin A2 interacts with Bora and PLK1. Expression of predominately cytoplasmic Cyclin A2 or phospho-mimicking PLK1 T210D can partially rescue a G2 arrest caused by Cyclin A2 depletion. Cytoplasmic presence of Cyclin A2 is restricted by p21, in particular after DNA damage. Cyclin A2 chromatin association during DNA replication and additional mechanisms contribute to Cyclin A2 localisation change in the G2 phase. We find no evidence that such mechanisms involve G2 feedback loops and suggest that cytoplasmic appearance of Cyclin A2 at the S/G2 transition functions as a trigger for mitotic kinase activation.

• MeSH
• aktivace enzymů genetika   MeSH
• buněčné jádro metabolismus   MeSH
• chromatin metabolismus   MeSH
• cyklin A2 genetika   metabolismus   MeSH
• cyklin-dependentní kinasa 2 nedostatek   genetika   MeSH
• cytoplazma metabolismus   MeSH
• fosforylace genetika   MeSH
• G2 fáze genetika   MeSH
• HeLa buňky MeSH
• lidé MeSH
• mitóza genetika   MeSH
• polo-like kinasa 1 MeSH
• poškození DNA genetika   MeSH
• protein-serin-threoninkinasy metabolismus   MeSH
• proteinkinasa CDC2 nedostatek   genetika   MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• protoonkogenní proteiny metabolismus   MeSH
• S fáze genetika   MeSH
• signální transdukce genetika   MeSH
• transfekce MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bora protein, human MeSH Prohlížeč
• CCNA2 protein, human MeSH Prohlížeč
• CDK1 protein, human MeSH Prohlížeč
• CDK2 protein, human MeSH Prohlížeč
• chromatin MeSH
• cyklin A2 MeSH
• cyklin-dependentní kinasa 2 MeSH
• protein-serin-threoninkinasy MeSH
• proteinkinasa CDC2 MeSH
• proteiny buněčného cyklu MeSH
• protoonkogenní proteiny MeSH

Genome integrity is protected by the cell-cycle checkpoints that prevent cell proliferation in the presence of DNA damage and allow time for DNA repair. The transient checkpoint arrest together with cellular senescence represent an intrinsic barrier to tumorigenesis. Tumor suppressor p53 is an integral part of the checkpoints and its inactivating mutations promote cancer growth. Protein phosphatase magnesium-dependent 1 (PPM1D) is a negative regulator of p53. Although its loss impairs recovery from the G2 checkpoint and promotes induction of senescence, amplification of the PPM1D locus or gain-of-function truncating mutations of PPM1D occur in various cancers. Here we used a transgenic mouse model carrying a truncating mutation in exon 6 of PPM1D (Ppm1dT). As with human cell lines, we found that the truncated PPM1D was present at high levels in the mouse thymus. Truncated PPM1D did not affect differentiation of T-cells in the thymus but it impaired their response to ionizing radiation (IR). Thymocytes in Ppm1dT/+ mice did not arrest in the checkpoint and continued to proliferate despite the presence of DNA damage. In addition, we observed a decreased level of apoptosis in the thymi of Ppm1dT/+ mice. Moreover, the frequency of the IR-induced T-cell lymphomas increased in Ppm1dT/+Trp53+/- mice resulting in decreased survival. We conclude that truncated PPM1D partially suppresses the p53 pathway in the mouse thymus and potentiates tumor formation under the condition of a partial loss of p53 function.

• Klíčová slova
• cancer, cell-cycle checkpoint, protein phosphatase, tumor suppressor p53,
• MeSH
• apoptóza * MeSH
• buněčný cyklus MeSH
• ionizující záření MeSH
• lymfom metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• nádory vyvolané zářením metabolismus   MeSH
• oprava DNA MeSH
• poškození DNA MeSH
• proliferace buněk MeSH
• proteinfosfatasa 2C fyziologie   MeSH
• thymocyty cytologie   metabolismus   MeSH
• thymus * cytologie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• nádorový supresorový protein p53 MeSH
• Ppm1d protein, mouse MeSH Prohlížeč
• proteinfosfatasa 2C MeSH
• Trp53 protein, mouse MeSH Prohlížeč

The most common histological subtypes of cutaneous melanoma include superficial spreading and nodular melanoma. However, the spectrum of somatic mutations developed in those lesions and all potential druggable targets have not yet been fully elucidated. We present the results of a sequence capture NGS analysis of 114 primary nodular and superficial spreading melanomas identifying driver mutations using biostatistical, immunohistochemical and/or functional approach. The spectrum and frequency of pathogenic or likely pathogenic variants were identified across 54 evaluated genes, including 59 novel mutations, and the newly identified TP53 loss-of-function mutations p.(L194P) and p.(R280K). Frequently mutated genes most commonly affected the MAPK pathway, followed by chromatin remodeling, and cell cycle regulation. Frequent aberrations were also detected in the genes coding for proteins involved in DNA repair and the regulation and modification of cellular tight junctions. Furthermore, relatively frequent mutations were described in KDR and MET, which represent potential clinically important targets. Those results suggest that with the development of new therapeutic possibilities, not only BRAF testing, but complex molecular testing of cutaneous melanoma may become an integral part of the decision process concerning the treatment of patients with melanoma.

• MeSH
• buněčný cyklus genetika   MeSH
• dospělí MeSH
• frekvence genu genetika   MeSH
• genetická predispozice k nemoci genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• maligní melanom kůže MeSH
• MAP kinasový signální systém genetika   MeSH
• melanom genetika   patologie   MeSH
• mladý dospělý MeSH
• mutace ztráty funkce genetika   MeSH
• nádorové biomarkery genetika   MeSH
• nádorový supresorový protein p53 genetika   MeSH
• nádory kůže genetika   patologie   MeSH
• oprava DNA genetika   MeSH
• protoonkogenní proteiny B-Raf genetika   MeSH
• restrukturace chromatinu genetika   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• těsný spoj genetika   MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• nádorové biomarkery MeSH
• nádorový supresorový protein p53 MeSH
• protoonkogenní proteiny B-Raf MeSH
• TP53 protein, human MeSH Prohlížeč

Protein phosphatase magnesium-dependent 1 delta (PPM1D) terminates cell response to genotoxic stress by negatively regulating the tumor suppressor p53 and other targets at chromatin. Mutations in the exon 6 of the PPM1D result in production of a highly stable, C-terminally truncated PPM1D. These gain-of-function PPM1D mutations are present in various human cancers but their role in tumorigenesis remains unresolved. Here we show that truncated PPM1D impairs activation of the cell cycle checkpoints in human non-transformed RPE cells and allows proliferation in the presence of DNA damage. Next, we developed a mouse model by introducing a truncating mutation in the PPM1D locus and tested contribution of the oncogenic PPM1DT allele to colon tumorigenesis. We found that p53 pathway was suppressed in colon stem cells harboring PPM1DT resulting in proliferation advantage under genotoxic stress condition. In addition, truncated PPM1D promoted tumor growth in the colon in Apcmin mice and diminished survival. Moreover, tumor organoids derived from colon of the ApcminPpm1dT/+ mice were less sensitive to 5-fluorouracil when compared to ApcminPpm1d+/+and the sensitivity to 5-fluorouracil was restored by inhibition of PPM1D. Finally, we screened colorectal cancer patients and identified recurrent somatic PPM1D mutations in a fraction of colon adenocarcinomas that are p53 proficient and show defects in mismatch DNA repair. In summary, we provide the first in vivo evidence that truncated PPM1D can promote tumor growth and modulate sensitivity to chemotherapy.

• MeSH
• chromatin účinky léků   MeSH
• exony genetika   MeSH
• fluoruracil farmakologie   MeSH
• karcinogeneze účinky léků   MeSH
• kontrolní body buněčného cyklu genetika   MeSH
• lidé MeSH
• mutace genetika   MeSH
• myši MeSH
• nádorový supresorový protein p53 genetika   MeSH
• nádory tračníku farmakoterapie   genetika   patologie   MeSH
• oprava DNA účinky léků   MeSH
• poškození DNA účinky léků   MeSH
• proliferace buněk účinky léků   MeSH
• protein familiární adenomatózní polypózy genetika   MeSH
• proteinfosfatasa 2C genetika   MeSH
• regulace genové exprese u nádorů účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenomatous polyposis coli protein, mouse MeSH Prohlížeč
• chromatin MeSH
• fluoruracil MeSH
• nádorový supresorový protein p53 MeSH
• PPM1D protein, human MeSH Prohlížeč
• protein familiární adenomatózní polypózy MeSH
• proteinfosfatasa 2C MeSH
• Trp53 protein, mouse MeSH Prohlížeč