Escape mutation
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Infection with high-risk types of human papillomavirus (HPV) can cause the development of malignant tumors. To study mechanisms responsible for immune escape of tumor cells infected with HPV16, we previously used mouse oncogenic TC-1 cells producing HPV16 E6 and E7 oncoproteins to derive TC-1 clones resistant to immunization against E7. We have found immunoresistance of the clones to correlate with the point mutation in the E7 oncogene, which resulted in the N53S substitution in the immunodominant epitope RAHYNIVTF (aa 49-57). Here, we have shown that this mutation reduced stabilization of H-2D(b) molecules on RMA-S cells and eliminated immunogenicity of E7. The resistance of TC-1 clones was E7-specific as immunization against E6 inhibited tumor growth. Transduction of the TC-1/F9 clone carrying the mutated epitope with the wild-type E7 gene restored susceptibility to immunization against E7. Our results suggest that mutagenesis of tumor antigens can lead to the escape of malignant cells and should be considered in the development and evaluation of cancer immunotherapy.
- MeSH
- antigeny nádorové chemie MeSH
- bodová mutace MeSH
- epitopy chemie MeSH
- financování organizované MeSH
- H-2 antigeny chemie MeSH
- imunodominantní epitopy chemie MeSH
- imunoterapie metody MeSH
- lidé MeSH
- mutace MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- nádory imunologie metabolismus terapie MeSH
- onkogenní proteiny virové genetika chemie MeSH
- onkogenní proteiny chemie MeSH
- Papillomavirus E7 - proteiny MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
Tick-borne encephalitis virus (TBEV) causes a severe and potentially fatal neuroinfection in humans. Despite its high medical relevance, no specific antiviral therapy is currently available. Here we demonstrate that treatment with a nucleoside analog, 7-deaza-2'-C-methyladenosine (7-deaza-2'-CMA), substantially improved disease outcomes, increased survival, and reduced signs of neuroinfection and viral titers in the brains of mice infected with a lethal dose of TBEV. To investigate the mechanism of action of 7-deaza-2'-CMA, two drug-resistant TBEV clones were generated and characterized. The two clones shared a signature amino acid substitution, S603T, in the viral NS5 RNA-dependent RNA polymerase (RdRp) domain. This mutation conferred resistance to various 2'-C-methylated nucleoside derivatives, but no cross-resistance was seen with other nucleoside analogs, such as 4'-C-azidocytidine and 2'-deoxy-2'-beta-hydroxy-4'-azidocytidine (RO-9187). All-atom molecular dynamics simulations revealed that the S603T RdRp mutant repels a water molecule that coordinates the position of a metal ion cofactor as 2'-C-methylated nucleoside analogs approach the active site. To investigate its phenotype, the S603T mutation was introduced into a recombinant TBEV strain (Oshima-IC) generated from an infectious cDNA clone and into a TBEV replicon that expresses a reporter luciferase gene (Oshima-REP-luc2A). The mutants were replication impaired, showing reduced growth and a small plaque size in mammalian cell culture and reduced levels of neuroinvasiveness and neurovirulence in rodent models. These results indicate that TBEV resistance to 2'-C-methylated nucleoside inhibitors is conferred by a single conservative mutation that causes a subtle atomic effect within the active site of the viral NS5 RdRp and is associated with strong attenuation of the virus.IMPORTANCE This study found that the nucleoside analog 7-deaza-2'-C-methyladenosine (7-deaza-2'-CMA) has high antiviral activity against tick-borne encephalitis virus (TBEV), a pathogen that causes severe human neuroinfections in large areas of Europe and Asia and for which there is currently no specific therapy. Treating mice infected with a lethal dose of TBEV with 7-deaza-2'-CMA resulted in significantly higher survival rates and reduced the severity of neurological signs of the disease. Thus, this compound shows promise for further development as an anti-TBEV drug. It is important to generate drug-resistant mutants to understand how the drug works and to develop guidelines for patient treatment. We generated TBEV mutants that were resistant not only to 7-deaza-2'-CMA but also to a broad range of other 2'-C-methylated antiviral medications. Our findings suggest that combination therapy may be used to improve treatment and reduce the emergence of drug-resistant viruses during nucleoside analog therapy for TBEV infection.
- MeSH
- antivirové látky terapeutické užití MeSH
- mutace MeSH
- myši MeSH
- nukleosidy * analogy a deriváty terapeutické užití MeSH
- virová léková rezistence MeSH
- viry klíšťové encefalitidy * účinky léků MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Monoclonal antibodies targeting CD38 are a therapeutic mainstay in multiple myeloma (MM). Although they have contributed to improved outcomes, most patients still experience disease relapse, and little is known about tumor-intrinsic mechanisms of resistance to these drugs. Antigen escape has been implicated as a mechanism of tumor-cell evasion in immunotherapy. Yet, it is unknown whether MM cells can develop permanent resistance to anti-CD38 antibodies by acquiring genomic events leading to biallelic disruption of the CD38 gene locus. Here, we analyzed whole-genome and whole-exome sequencing data from patients 701 newly diagnosed MM, 67 patients at relapse with naivety to anti-CD38 antibodies, and 50 patients collected at relapse after anti-CD38 antibodies. We report a loss of CD38 in 10 of 50 patients (20%) after CD38 therapy, 3 of whom exhibited a loss of both copies. Two of these cases showed convergent evolution in which distinct subclones independently acquired similar advantageous variants. Functional studies on missense mutations involved in biallelic CD38 events revealed that 2 variants, L153H and C275Y, decreased binding affinity and antibody-dependent cellular cytotoxicity of the commercial antibodies daratumumab and isatuximab. However, a third mutation, R140G, conferred selective resistance to daratumumab, while retaining sensitivity to isatuximab. Clinically, patients with MM are often rechallenged with CD38 antibodies after disease progression and these data suggest that next-generation sequencing may play a role in subsequent treatment selection for a subset of patients.
- MeSH
- alely MeSH
- antigeny CD38 * genetika imunologie antagonisté a inhibitory MeSH
- chemorezistence * genetika MeSH
- humanizované monoklonální protilátky MeSH
- lidé MeSH
- membránové glykoproteiny * genetika imunologie MeSH
- mnohočetný myelom * genetika imunologie farmakoterapie patologie MeSH
- monoklonální protilátky * terapeutické užití farmakologie MeSH
- únik nádoru z imunitní kontroly * genetika MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
The Delta variant is one of the alarming variants of the SARS-CoV-2 virus that have been immensely detrimental and a significant cause of the prolonged pandemic (B.1.617.2). During the SARS-CoV-2 pandemic from December 2020 to October 2021, the Delta variant showed global dominance, and afterwards, the Omicron variant showed global dominance. Delta shows high infectivity rate which accounted for nearly 70% of the cases after December 2020. This review discusses the additional attributes that make the Delta variant so infectious and transmissible. The study also focuses on the significant mutations, namely the L452R and T478K present on the receptor-binding domain of spike (S)-glycoprotein, which confers specific alterations to the Delta variant. Considerably, we have also highlighted other notable factors such as the immune escape, infectivity and re-infectivity, vaccine escape, Ro number, S-glycoprotein stability, cleavage pattern, and its binding affinity with the host cell receptor protein. We have also emphasized clinical manifestations, symptomatology, morbidity, and mortality for the Delta variant compared with other significant SARS-CoV-2 variants. This review will help the researchers to get an elucidative view of the Delta variant to adopt some practical strategies to minimize the escalating spread of the SARS-CoV-2 Delta variant.
- MeSH
- COVID-19 * MeSH
- lidé MeSH
- mutace MeSH
- SARS-CoV-2 * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
According to previous reports in the literature, the T790M mutation indicates an acquired resistance to tyrosine kinase inhibitors. The initial positive effect of combination chemotherapy with erlotinib as the first line of treatment correlates with several positive predictors including the type of carcinoma, non-smoking status, occurrence of rash and the presence of exon 19 EGFR gene mutation. The case of a 32-year-old, non-smoker with non-contributory history patient, who was diagnosed with adenocarcinoma in the left lung T4N0M0 stage IIIB is reported. The patient underwent 6 cycles of chemotherapy with erlotinib, gemcitabine and cisplatin, followed by complete remission. Fifteen months after commencing therapy, disease recurred over subsequent therapy with erlotinib and then gefitinib. During that time, bone and cerebral metastases with pericardial effusion were detected. The patient died 7 months later. Genetic examination of tumour tissue collected at the beginning of therapy revealed activating exon 19 mutation in the EGFR gene. Later, during the relapse, the same mutation was still present and, in addition, a T790M mutation in exon 20 of EGFR was found. The subsequently acquired resistance against both erlotinib, as well as gefitinib was most likely a result of tumor cells acquiring the T790M mutations and escaping the drug effect. The authors recommend testing for T790M mutation presence in selected patients prior to targeted therapy with tyrosine kinase inhibitors.
- MeSH
- adenokarcinom farmakoterapie genetika MeSH
- chemorezistence genetika MeSH
- chinazoliny aplikace a dávkování MeSH
- cisplatina aplikace a dávkování MeSH
- deoxycytidin analogy a deriváty aplikace a dávkování MeSH
- dospělí MeSH
- erbB receptory genetika MeSH
- financování organizované MeSH
- jednonukleotidový polymorfismus MeSH
- lidé MeSH
- molekulární sekvence - údaje MeSH
- mutace MeSH
- nádory plic farmakoterapie genetika MeSH
- protokoly protinádorové kombinované chemoterapie terapeutické užití MeSH
- sekvence nukleotidů MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
Cancer immunotherapy is increasingly used in clinical practice, but its success rate is reduced by tumor escape from the immune system. This may be due to the genetic instability of tumor cells, which allows them to adapt to the immune response and leads to intratumoral immune heterogeneity. The study investigated spatial immune heterogeneity in the tumor microenvironment and its possible drivers in a mouse model of tumors induced by human papillomaviruses (HPV) following immunotherapy. Gene expression was determined by RNA sequencing and mutations by whole exome sequencing. A comparison of different tumor areas revealed heterogeneity in immune cell infiltration, gene expression, and mutation composition. While the mean numbers of mutations with every impact on gene expression or protein function were comparable in treated and control tumors, mutations with high or moderate impact were increased after immunotherapy. The genes mutated in treated tumors were significantly enriched in genes associated with ECM metabolism, degradation, and interactions, HPV infection and carcinogenesis, and immune processes such as antigen processing and presentation, Toll-like receptor signaling, and cytokine production. Gene expression analysis of DNA damage and repair factors revealed that immunotherapy upregulated Apobec1 and Apobec3 genes and downregulated genes related to homologous recombination and translesion synthesis. In conclusion, this study describes the intratumoral immune heterogeneity, that could lead to tumor immune escape, and suggests the potential mechanisms involved.
- MeSH
- imunoterapie * metody MeSH
- infekce papilomavirem imunologie virologie MeSH
- lidé MeSH
- modely nemocí na zvířatech * MeSH
- mutace * MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- nádorové mikroprostředí * imunologie MeSH
- regulace genové exprese u nádorů MeSH
- sekvenování exomu MeSH
- únik nádoru z imunitní kontroly genetika MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The RNA-dependent RNA polymerases of Flaviviridae viruses are crucial for replication. The Flaviviridae polymerase is organized into structural motifs (A-G), with motifs F, A, C and E containing interrogating, priming and catalytic substrate-interacting sites. Modified nucleoside analogues act as antiviral drugs by targeting Flaviviridae polymerases and integrating into the synthesized product causing premature termination. A threonine mutation of a conserved serine residue in motif B of Flaviviridae polymerases renders resistance to 2'-C-methylated nucleoside analogues. The mechanism how this single mutation causes Flaviviridae viruses to escape nucleoside analogues is not yet known. Given the pivotal position of the serine residue in motif B that supports motif F, we hypothesized the threonine mutation causes alterations in nucleoside exploration within the entry tunnel. Implementing a stochastic molecular software showed the all-atom 2'-C-methylated analogue reaction within the active sites of wild type and serine-threonine mutant polymerases from Hepacivirus and Flavivirus. Compared with the wild type, the serine-threonine mutant polymerases caused a significant decrease of analogue contacts with conserved interrogating residues in motif F and a displacement of metal ion cofactors. The simulations significantly showed that during the analogue exploration of the active site the hydrophobic methyl group in the serine-threonine mutant repels water-mediated hydrogen bonds with the 2'-C-methylated analogue, causing a concentration of water-mediated bonds at the substrate-interacting sites. Collectively, the data are an insight into a molecular escape mechanism by Flaviviridae viruses from 2'-C-methylated nucleoside analogue inhibitors.
Autosomal recessive polycystic kidney disease (ARPKD) is a severe disease of early childhood that is clinically characterized by fibrocystic changes of the kidneys and the liver. The main cause of ARPKD are variants in the PKHD1 gene encoding the large transmembrane protein fibrocystin. The mechanisms underlying the observed clinical heterogeneity in ARPKD remain incompletely understood, partly due to the fact that genotype-phenotype correlations have been limited to the association of biallelic null variants in PKHD1 with the most severe phenotypes. In this observational study we analyzed a deep clinical dataset of 304 patients with ARPKD from two independent cohorts and identified novel genotype-phenotype correlations during childhood and adolescence. Biallelic null variants frequently show severe courses. Additionally, our data suggest that the affected region in PKHD1 is important in determining the phenotype. Patients with two missense variants affecting amino acids 709-1837 of fibrocystin or a missense variant in this region and a null variant less frequently developed chronic kidney failure, and patients with missense variants affecting amino acids 1838-2624 showed better hepatic outcome. Variants affecting amino acids 2625-4074 of fibrocystin were associated with poorer hepatic outcome. Thus, our data expand the understanding of genotype-phenotype correlations in pediatric ARPKD patients and can lay the foundation for more precise and personalized counselling and treatment approaches.
- MeSH
- dítě MeSH
- fenotyp MeSH
- genetické asociační studie MeSH
- ledviny MeSH
- lidé MeSH
- mutace MeSH
- polycystické ledviny autozomálně recesivní * diagnóza genetika MeSH
- předškolní dítě MeSH
- receptory buněčného povrchu genetika MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- předškolní dítě MeSH
- Publikační typ
- časopisecké články MeSH
- pozorovací studie MeSH
- práce podpořená grantem MeSH
AIMS: This study aimed to examine changes in the repertoire of functional T-cells specific for six leukemia-associated antigens (LAA), including WT1, PRAME, MUC1, CCNA1, NPM1, and NPM1c, during immune reconstitution following allogeneic transplantation of hematopoietic stem cells (HSCT) in patients with acute myeloid leukemia. PATIENTS & METHODS: LAA-specific T cell response was measured by ELISPOT- IFNγ and intracellular cytokine staining in 47 patients before starting conditioning therapy (baseline) and 7 months after HSCT. RESULTS: The positive cumulative LAA-specific T cell response before HSCT was associated with a decreased risk of relapse after HSCT. The prevalent genetic aberration - an internal tandem duplication of Fms 3 - related receptor tyrosine kinase, which has been previously implicated in immune escape mechanisms, is presented here for the first time as a factor associated with the absence of an adaptive T cell response against multiple LAAs. T-cell specific responses against wild-type and mutated NPM1 antigens were less frequent in the study cohort and did not correlate with mutations in the NPM1 gene. CONCLUSIONS: Our results showed that the T-cell response to LAA can be reconstituted after HSCT. Measurement of functional pre-transplant T-cell responses against multiple LAAs could help to find patients with an increased risk of relapse.
- MeSH
- akutní myeloidní leukemie * terapie imunologie genetika MeSH
- antigeny nádorové imunologie MeSH
- dospělí MeSH
- homologní transplantace MeSH
- jaderné proteiny genetika MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mucin 1 genetika imunologie MeSH
- mutace * MeSH
- nukleofosmin * MeSH
- proteiny WT1 imunologie genetika MeSH
- recidiva MeSH
- senioři MeSH
- T-lymfocyty * imunologie MeSH
- transplantace hematopoetických kmenových buněk * MeSH
- tyrosinkinasa 3 podobná fms * genetika MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
