Accumulation of mutations and chromosomal aberrations is one of the hallmarks of cancer cells. This enhanced genetic instability is fueled by defects in the genome maintenance mechanisms including DNA repair and cell cycle checkpoint pathways. Here, we discuss the emerging roles of the mammalian Chk1 and Chk2 kinases as key signal transducers within the complex network of genome integrity checkpoints, as candidate tumor suppressors disrupted in sporadic as well as some hereditary malignancies and as potential targets of new anticancer therapies.

• MeSH
• biologické modely MeSH
• buněčný cyklus MeSH
• checkpoint kinasa 2 MeSH
• lidé MeSH
• mutace * MeSH
• myši knockoutované MeSH
• myši MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• nádory prsu enzymologie   metabolismus   MeSH
• nádory tračníku enzymologie   MeSH
• nádory * genetika   MeSH
• oprava DNA MeSH
• protein-serin-threoninkinasy fyziologie   genetika   MeSH
• proteinkinasy fyziologie   genetika   MeSH
• signální transdukce MeSH
• terciární struktura proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH

Immune checkpoint blockade (ICB) using monoclonal antibodies against programmed cell death protein 1 (PD-1) or programmed death-ligand 1 (PD-L1) is the treatment of choice for cancer immunotherapy. However, low tissue permeability, immunogenicity, immune-related adverse effects, and high cost could be possibly improved using alternative approaches. On the other hand, synthetic low-molecular-weight (LMW) PD-1/PD-L1 blockers have failed to progress beyond in vitro studies, mostly due to low binding affinity or poor pharmacological characteristics resulting from their limited solubility and/or stability. Here, we report the development of polymer-based anti-human PD-L1 antibody mimetics (α-hPD-L1 iBodies) by attaching the macrocyclic peptide WL12 to a N-(2-hydroxypropyl)methacrylamide copolymer. We characterized the binding properties of iBodies using surface plasmon resonance, enzyme-linked immunosorbent assay, flow cytometry, confocal microscopy, and a cellular ICB model. We found that the α-hPD-L1 iBodies specifically target human PD-L1 (hPD-L1) and block the PD-1/PD-L1 interaction in vitro, comparable to the atezolizumab, durvalumab, and avelumab licensed monoclonal antibodies targeting PD-L1. Our findings suggest that iBodies can be used as experimental tools to target hPD-L1 and could serve as a platform to potentiate the therapeutic effect of hPD-L1-targeting small molecules by improving their affinity and pharmacokinetic properties.

• MeSH
• antigeny CD274 * antagonisté a inhibitory   imunologie   metabolismus   MeSH
• inhibitory kontrolních bodů * farmakologie   chemie   MeSH
• lidé MeSH
• monoklonální protilátky chemie   farmakologie   MeSH
• nádorové buněčné linie MeSH
• polymery chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

COVID-19 (Coronavirus Disease) is an infectious disease caused by the coronavirus SARS-CoV-2 (Severe acute respiratory syndrome Coronavirus 2), which belongs to the genus Betacoronavirus. It was first identified in patients with severe respiratory disease in December 2019 in Wuhan, China. It mainly affects the respiratory system, and in severe cases causes serious lung infection or pneumonia, which can lead to the death of the patient. Clinical studies show that SARS-CoV-2 infection in critical cases causes acute tissue damage due to a pathological immune response. The immune response to a new coronavirus is complex and involves many processes of specific and non-specific immunity. Analysis of available studies has shown various changes, especially in the area of specific cellular immunity, including lymphopenia, decreased T cells (CD3+, CD4+ and CD8+), changes in the T cell compartment associated with symptom progression, deterioration of the condition and development of lung damage. We provide a detailed review of the analyses of immune checkpoint molecules PD-1, TIM-3, LAG-3 CTLA-4, TIGIT, BTLA, CD223, IDO-1 and VISTA on exhausted T cells in patients with asymptomatic to symptomatic stages of COVID-19 infection. Furthermore, this review may help to better understand the pathological T cell immune response and improve the design of therapeutic strategies for patients with SARS-CoV-2 infection.

• MeSH
• COVID-19 imunologie   metabolismus   virologie   MeSH
• fenotyp MeSH
• interakce hostitele a patogenu MeSH
• lidé MeSH
• proteiny kontrolních bodů imunitní reakce metabolismus   MeSH
• SARS-CoV-2 imunologie   patogenita   MeSH
• signální transdukce MeSH
• T-lymfocyty imunologie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

p53-mutated tumors often exhibit increased resistance to standard chemotherapy and enhanced metastatic potential. Here we demonstrate that inhibition of dihydroorotate dehydrogenase (DHODH), a key enzyme of the de novo pyrimidine synthesis pathway, effectively decreases proliferation of cancer cells via induction of replication and ribosomal stress in a p53- and checkpoint kinase 1 (Chk1)-dependent manner. Mechanistically, a block in replication and ribosomal biogenesis result in p53 activation paralleled by accumulation of replication forks that activate the ataxia telangiectasia and Rad3-related kinase/Chk1 pathway, both of which lead to cell cycle arrest. Since in the absence of functional p53 the cell cycle arrest fully depends on Chk1, combined DHODH/Chk1 inhibition in p53-dysfunctional cancer cells induces aberrant cell cycle re-entry and erroneous mitosis, resulting in massive cell death. Combined DHODH/Chk1 inhibition effectively suppresses p53-mutated tumors and their metastasis, and therefore presents a promising therapeutic strategy for p53-mutated cancers.

• MeSH
• checkpoint kinasa 1 antagonisté a inhibitory   genetika   metabolismus   MeSH
• fenylmočovinové sloučeniny farmakologie   MeSH
• geny erbB-2 MeSH
• HCT116 buňky MeSH
• inhibitory proteinkinas farmakologie   MeSH
• kontrolní body buněčného cyklu * účinky léků   MeSH
• leflunomid farmakologie   MeSH
• lidé MeSH
• MFC-7 buňky MeSH
• myši inbrední BALB C MeSH
• myši inbrední NOD MeSH
• myši SCID MeSH
• myši transgenní MeSH
• nádorový supresorový protein p53 nedostatek   genetika   MeSH
• nádory prsu farmakoterapie   genetika   metabolismus   patologie   MeSH
• oxidoreduktasy působící na CH-CH vazby antagonisté a inhibitory   genetika   metabolismus   MeSH
• proliferace buněk * účinky léků   MeSH
• protokoly protinádorové kombinované chemoterapie farmakologie   MeSH
• pyraziny farmakologie   MeSH
• pyrimidiny biosyntéza   MeSH
• regulace genové exprese u nádorů MeSH
• ribozomy genetika   metabolismus   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The immune checkpoint inhibitors have revolutionized cancer immunotherapy. These inhibitors are game changers in many cancers and for many patients, sometimes show unprecedented therapeutic efficacy. However, their therapeutic efficacy is largely limited in many solid tumors where the tumor-controlled immune microenvironment prevents the immune system from efficiently reaching, recognizing, and eliminating cancer cells. The tumor immune microenvironment is largely orchestrated by immune cells through which tumors gain resistance against the immune system. Among these cells are mast cells and dendritic cells. Both cell types possess enormous capabilities to shape the immune microenvironment. These capabilities stage these cells as cellular checkpoints in the immune microenvironment. Regaining control over these cells in the tumor microenvironment can open new avenues for breaking the resistance of solid tumors to immunotherapy. In this review, we will discuss mast cells and dendritic cells in the context of solid tumors and how these immune cells can, alone or in cooperation, modulate the solid tumor resistance to the immune system. We will also discuss how this modulation could be used in novel immunotherapeutic modalities to weaken the solid tumor resistance to the immune system. This weakening could then help other immunotherapeutic modalities engage against these tumors more efficiently.

• MeSH
• dendritické buňky patologie   MeSH
• imunoterapie MeSH
• inhibitory kontrolních bodů MeSH
• lidé MeSH
• mastocyty * patologie   MeSH
• nádorové mikroprostředí MeSH
• nádory * patologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

After DNA damage, the cell cycle is arrested to avoid propagation of mutations. Arrest in G2 phase is initiated by ATM-/ATR-dependent signaling that inhibits mitosis-promoting kinases such as Plk1. At the same time, Plk1 can counteract ATR-dependent signaling and is required for eventual resumption of the cell cycle. However, what determines when Plk1 activity can resume remains unclear. Here, we use FRET-based reporters to show that a global spread of ATM activity on chromatin and phosphorylation of ATM targets including KAP1 control Plk1 re-activation. These phosphorylations are rapidly counteracted by the chromatin-bound phosphatase Wip1, allowing cell cycle restart despite persistent ATM activity present at DNA lesions. Combining experimental data and mathematical modeling, we propose a model for how the minimal duration of cell cycle arrest is controlled. Our model shows how cell cycle restart can occur before completion of DNA repair and suggests a mechanism for checkpoint adaptation in human cells.

• MeSH
• ATM protein metabolismus   MeSH
• biologické modely MeSH
• buněčné linie MeSH
• chromatin metabolismus   MeSH
• fosforylace MeSH
• kontrolní body fáze G2 buněčného cyklu * MeSH
• lidé MeSH
• mapování interakce mezi proteiny MeSH
• posttranslační úpravy proteinů MeSH
• protein-serin-threoninkinasy metabolismus   MeSH
• proteinfosfatasa 2C metabolismus   MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• protoonkogenní proteiny metabolismus   MeSH
• represorové proteiny metabolismus   MeSH
• rezonanční přenos fluorescenční energie MeSH
• teoretické modely MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Checkpoint adaptation was originally defined in yeast as the ability to divide despite the presence of damaged DNA. An important unanswered question is whether checkpoint adaptation also occurs in human cells. Here, we show that following the ionizing radiation-induced G(2) checkpoint, human osteosarcoma cells entered mitosis with gamma-H2AX foci, a marker for unrepaired DNA double-strand breaks. Exit from the G(2) checkpoint was accelerated by inhibiting the checkpoint kinase 1 (Chk1) and delayed by overexpressing wild-type Chk1 or depleting the Polo-like kinase 1 (Plk1). Chk1 and Plk1 controlled this process, at least partly, via independent signaling pathways. Our results suggest that human cells are able to exit the checkpoint arrest and divide before the damage has been fully repaired. Such cell division in the presence of damaged DNA may be detrimental for genetic stability and could potentially contribute to cancer development.

• MeSH
• fyziologická adaptace MeSH
• G2 fáze * účinky záření   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• poškození DNA MeSH
• protein-serin-threoninkinasy * fyziologie   MeSH
• proteinkinasy * fyziologie   MeSH
• proteiny buněčného cyklu * fyziologie   MeSH
• protoonkogenní proteiny * fyziologie   MeSH
• Check Tag
• lidé MeSH

Monoklonální protilátky se staly jedním z nejdůležitějších protinádorových terapeutických prostředků. Jedním z mechanismů jejich účinku je buněčná cytotoxicita zprostředkovaná protilátkami (ADCC). Nádorové buňky opsonizované protilátkami mohou být cytotoxicky likvidovány imunitními buňkami vybavenými Fc receptory (NK a NKT lymfocyty, většina myeloidních buněk). Tento mechanismus se uplatňuje paralelně s ostatními známými mechanismy (fagocytóza opsonizovaných buněk, lýza po aktivaci klasické dráhy komplementu, blokování funkce receptorů růstových faktorů, blokování tlumivých „kontrolních bodů ).

• MeSH
• buněčná cytotoxicita závislá na protilátkách * fyziologie   účinky léků   MeSH
• buňky NK fyziologie   MeSH
• cílená molekulární terapie * metody   MeSH
• humorální imunita fyziologie   účinky léků   MeSH
• imunoglobuliny fyziologie   imunologie   MeSH
• inhibitory kontrolních bodů farmakologie   MeSH
• lidé MeSH
• monoklonální protilátky farmakologie   imunologie   MeSH
• nádory farmakoterapie   imunologie   MeSH
• receptory Fc fyziologie   MeSH
• Check Tag
• lidé MeSH

BACKGROUND/AIM: Classic Hodgkin lymphoma (cHL) is a common B-cell malignancy. Despite the good prognosis, in some patients the standard chemotherapy and radiotherapy-based approach does not lead to long-term remission, and these patients eventually relapse. Moreover, the primary refractory disease is of major concern regarding prognosis. PATIENTS AND METHODS: We performed a retrospective analysis to evaluate PD-L1 expression in 120 patients with classic Hodgkin lymphoma (cHL). RESULTS: The median follow-up of the entire group of patients was 90 months. After initial therapy, complete remission was achieved in 113 (94.2%) patients. During the follow-up, cHL relapse/refractory disease was reported in 23 (19.2%) cases. A total of five patients died during the follow-up period, all from cHL progression. When determining PD-L1 expression on Hodgkin-Reed-Sternberg (HRS) cells, 37 cases (30.8%) were evaluated as negative, and 83 cases (69.2%) as positive. In the negative PD-L1 group of patients, no cHL relapse/refractory disease was observed during the follow-up period. However, out of 83 patients with positive PD-L1 expression on HRS cells, 23 (28%) showed relapse/refractory cHL. CONCLUSION: A significantly higher relapse rate was observed in PD-L1-positive patients diagnosed with cHL.

• MeSH
• antigeny CD274 genetika   MeSH
• Hodgkinova nemoc * farmakoterapie   MeSH
• lidé MeSH
• lokální recidiva nádoru MeSH
• prognóza MeSH
• proteiny kontrolních bodů imunitní reakce terapeutické užití   MeSH
• retrospektivní studie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

DNA lesions trigger the DNA damage response (DDR) machinery, which protects genomic integrity and sustains cellular survival. Increasing data underline the significance of the integrity of the DDR pathway in chemotherapy response. According to a recent work, persistent exposure of A549 lung carcinoma cells to doxorubicin induces an initial DDR-dependent checkpoint response, followed by a later DDR-independent, but p27(Kip1)-dependent one. Prompted by the above report and to better understand the involvement of the DDR signaling after chemotherapeutic stress, we examined the potential role of the canonical DDR pathway in A549 cells treated with doxorubicin. Exposure of A549 cells, prior to doxorubicin treatment, to ATM, ATR and DNA-PKcs inhibitors either alone or in various combinations, revealed that the earlier documented two-step response was DDR-dependent in both steps. Notably, inhibition of both ATM and ATR or selective inhibition of ATM or DNA-PKcs resulted in cell-cycle re-entry despite the increased levels of p27(Kip1) at all time points analyzed. We further investigated the regulation of p27(Kip1) protein levels in the particular setting. Our results showed that the protein status of p27(Kip1) is mainly determined by p38-MAPK, whereas the role of SKP2 is less significant in the doxoroubicin-treated A549 cells. Cumulatively, we provide evidence that the DNA damage signaling is responsible for the prolonged cell cycle arrest observed after persistent chemotherapy-induced genotoxic stress. In conclusion, precise identification of the molecular mechanisms that are activated during the chemotherapeutic cycles could potentially increase the sensitization to the therapy applied.

• MeSH
• ATM protein antagonisté a inhibitory   MeSH
• buňky A549 MeSH
• chromony farmakologie   MeSH
• doxorubicin farmakologie   MeSH
• inhibitor p27 cyklin-dependentní kinasy fyziologie   MeSH
• kofein farmakologie   MeSH
• kontrolní body fáze G2 buněčného cyklu účinky léků   MeSH
• lidé MeSH
• mitogenem aktivované proteinkinasy p38 metabolismus   MeSH
• morfoliny farmakologie   MeSH
• poškození DNA MeSH
• proteinkinasa aktivovaná DNA antagonisté a inhibitory   MeSH
• proteiny asociované s kinázou S-fáze metabolismus   MeSH
• protinádorové látky farmakologie   MeSH
• pyrony farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH