RESUMEN
Mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) gastric cancer (GC) exhibits an immune-active tumor microenvironment (TME) compared to MMR proficient (pMMR)/microsatellite stable/Epstein-Barr virus-negative [EBV (-)] GC. The tumor cell-intrinsic cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has been considered a key regulator of immune cell activation in the TME. However, its significance in regulating the immune-active TME in dMMR/MSI-H GC remains unclear. Here, we demonstrated that tumor cell-intrinsic cGAS-STING was highly expressed in dMMR GC compared to pMMR/EBV (-) GC. The expression of tumor cell-intrinsic STING was significantly and positively associated with the number of CD8+ tumor-infiltrating lymphocytes in GC. Analysis of TCGA datasets revealed that the expression of interferon-stimulated genes and STING downstream T-cell attracting chemokines was significantly higher in MSI-H GC compared to other subtypes of GC with EBV (-). These results suggest that tumor cell-intrinsic STING signaling plays a key role in activating immune cells in the dMMR/MSI-H GC TME and might serve as a novel biomarker predicting the efficacy of immunotherapy for GC treatment.
Asunto(s)
Linfocitos T CD8-positivos , Linfocitos Infiltrantes de Tumor , Proteínas de la Membrana , Inestabilidad de Microsatélites , Transducción de Señal , Neoplasias Gástricas , Microambiente Tumoral , Neoplasias Gástricas/genética , Neoplasias Gástricas/inmunología , Neoplasias Gástricas/patología , Neoplasias Gástricas/metabolismo , Humanos , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/genética , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Linfocitos Infiltrantes de Tumor/inmunología , Linfocitos Infiltrantes de Tumor/metabolismo , Microambiente Tumoral/inmunología , Masculino , Femenino , Reparación de la Incompatibilidad de ADN/genética , Persona de Mediana Edad , Nucleotidiltransferasas/metabolismo , Nucleotidiltransferasas/genética , Regulación Neoplásica de la Expresión Génica , AncianoRESUMEN
Deficient (d) DNA mismatch repair (MMR) is a biomarker predictive of better response to PD-1 blockade immunotherapy in solid tumors. dMMR can be caused by mutations in MMR genes or by protein inactivation, which can be detected by sequencing and immunohistochemistry, respectively. To investigate the role of dMMR in diffuse large B-cell lymphoma (DLBCL), MMR gene mutations and expression of MSH6, MSH2, MLH1, and PMS2 proteins were evaluated by targeted next-generation sequencing and immunohistochemistry in a large cohort of DLBCL patients treated with standard chemoimmunotherapy, and correlated with the tumor immune microenvironment characteristics quantified by fluorescent multiplex immunohistochemistry and gene-expression profiling. The results showed that genetic dMMR was infrequent in DLBCL and was significantly associated with increased cancer gene mutations and favorable immune microenvironment, but not prognostic impact. Phenotypic dMMR was also infrequent, and MMR proteins were commonly expressed in DLBCL. However, intratumor heterogeneity existed, and increased DLBCL cells with phenotypic dMMR correlated with significantly increased T cells and PD-1+ T cells, higher average nearest neighbor distance between T cells and PAX5+ cells, upregulated immune gene signatures, LE4 and LE7 ecotypes and their underlying Ecotyper-defined cell states, suggesting the possibility that increased T cells targeted only tumor cell subsets with dMMR. Only in patients with MYC¯ DLBCL, high MSH6/PMS2 expression showed significant adverse prognostic effects. This study shows the immunologic and prognostic effects of genetic/phenotypic dMMR in DLBCL, and raises a question on whether DLBCL-infiltrating PD-1+ T cells target only tumor subclones, relevant for the efficacy of PD-1 blockade immunotherapy in DLBCL.
Asunto(s)
Reparación de la Incompatibilidad de ADN , Linfoma de Células B Grandes Difuso , Microambiente Tumoral , Humanos , Linfoma de Células B Grandes Difuso/genética , Linfoma de Células B Grandes Difuso/inmunología , Linfoma de Células B Grandes Difuso/patología , Reparación de la Incompatibilidad de ADN/genética , Microambiente Tumoral/inmunología , Microambiente Tumoral/genética , Masculino , Femenino , Mutación , Persona de Mediana Edad , Anciano , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Pronóstico , Adulto , Endonucleasa PMS2 de Reparación del Emparejamiento Incorrecto/genética , Endonucleasa PMS2 de Reparación del Emparejamiento Incorrecto/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismoRESUMEN
AIM: Lynch syndrome (LS) is estimated to affect 1-3.9% of patients with colorectal cancer (CRC). Testing for LS is important in determining management and establishing surveillance for "Lynch families". Previous studies have identified poor rates of testing for LS in CRC patients. This study aimed to describe adherence to guidelines for testing of newly diagnosed CRC for LS. METHODS: A single institution cohort study of patients over 18 years with colorectal adenocarcinoma from 2018-2022 in Te Tai Tokerau, Aotearoa New Zealand was conducted. Rates of baseline immunohistochemistry (IHC) testing for mismatch repair (MMR) deficiency, further testing for MLH1-deficient cases and rates of germline mutational analysis were audited to determine adherence to national guidelines. The rate of LS in newly diagnosed CRC was estimated. RESULTS: Six hundred and sixty patients were eligible for universal testing for LS, of which 84% (n=553) completed initial IHC testing. MMR deficiency was reported in 20% (n=114) cases. Eighty-nine percent (n=101) was attributable to MLH1 deficiency, of which 99% (n=100) were appropriately tested for BRAF-V600E mutation. Sixty-four percent (4/11) patients indicated for hypermethylation testing were appropriately tested. Seventeen patients had an indication for germline mutational analysis, of which only 29% (n=5) were tested. The estimated incidence of LS in newly diagnosed CRC was 0.7-3.8%. CONCLUSION: Compliance with initial IHC testing was good. However, there is a need to improve rates of confirmation genetic testing. The incidence of confirmed LS in this study is 0.7%, however this may be as high as 3.9%.
Asunto(s)
Neoplasias Colorrectales Hereditarias sin Poliposis , Neoplasias Colorrectales , Adhesión a Directriz , Humanos , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/diagnóstico , Nueva Zelanda , Femenino , Masculino , Adhesión a Directriz/estadística & datos numéricos , Persona de Mediana Edad , Anciano , Adulto , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/diagnóstico , Pruebas Genéticas/métodos , Reparación de la Incompatibilidad de ADN/genética , Guías de Práctica Clínica como Asunto , Homólogo 1 de la Proteína MutL/genética , Anciano de 80 o más Años , InmunohistoquímicaRESUMEN
BackgroundLynch syndrome (LS) is an inherited cancer predisposition syndrome caused by genetic variants affecting DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2 Cancer risk in LS is estimated from cohorts of individuals ascertained by individual or family history of cancer, which may upwardly bias estimates. METHODS: 830 carriers of pathogenic or likely pathogenic (path_MMR) MMR gene variants classified by InSiGHT were identified in 454 756 UK Biobank (UKB) participants using whole-exome sequence. Nelson-Aalen survival analysis was used to estimate cumulative incidence of colorectal, endometrial and breast cancer (BC). RESULTS: Cumulative incidence of colorectal and endometrial cancer (EC) by age 70 years was elevated in path_MMR carriers compared with non-carriers (colorectal: 11.8% (95% confidence interval (CI): 9.5% to 14.6%) vs 1.7% (95% CI: 1.6% to 1.7%), endometrial: 13.4% (95% CI: 10.2% to 17.6%) vs 1.0% (95% CI: 0.9% to 1.0%)), but the magnitude of this increase differed between genes. Cumulative BC incidence by age 70 years was not elevated in path_MMR carriers compared with non-carriers (8.9% (95% CI: 6.3% to 12.4%) vs 7.5% (95% CI: 7.4% to 7.6%)). Cumulative cancer incidence estimates in UKB were similar to estimates from the Prospective Lynch Syndrome Database for all genes and cancers, except there was no evidence for elevated EC risk in carriers of pathogenic PMS2 variants in UKB. CONCLUSION: These results support offering incidentally identified carriers of any path_MMR surveillance to manage colorectal cancer risk. Incidentally identified carriers of pathogenic variants in MLH1, MSH2 and MSH6 would also benefit from interventions to reduce EC risk. The results suggest that BC is not an LS-related cancer.
Asunto(s)
Bancos de Muestras Biológicas , Neoplasias Colorrectales Hereditarias sin Poliposis , Reparación de la Incompatibilidad de ADN , Predisposición Genética a la Enfermedad , Humanos , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/epidemiología , Femenino , Reino Unido/epidemiología , Masculino , Persona de Mediana Edad , Reparación de la Incompatibilidad de ADN/genética , Anciano , Heterocigoto , Secuenciación del Exoma , Incidencia , Adulto , Neoplasias de la Mama/genética , Neoplasias de la Mama/epidemiología , Neoplasias Endometriales/genética , Neoplasias Endometriales/epidemiología , Proteínas de Unión al ADN/genética , Homólogo 1 de la Proteína MutL/genética , Biobanco del Reino Unido , Proteína 2 Homóloga a MutSRESUMEN
Somatic hypermutation in cancer has gained momentum with the increased use of tumour mutation burden as a biomarker for immune checkpoint inhibitors. Spontaneous deamination of 5-methylcytosine to thymine at CpG dinucleotides is one of the most ubiquitous endogenous mutational processes in normal and cancer cells. Here, we performed a systematic investigation of somatic CpG hypermutation at a pan-cancer level. We studied 30,191 cancer patients and 103 cancer types and developed an algorithm to identify somatic CpG hypermutation. Across cancer types, we observed the highest prevalence in paediatric leukaemia (3.5%), paediatric high-grade glioma (1.7%), and colorectal cancer (1%). We discovered germline variants and somatic mutations in the mismatch repair complex MutSα (MSH2-MSH6) as genetic drivers of somatic CpG hypermutation in cancer, which frequently converged on CpG sites and TP53 driver mutations. We further observe an association between somatic CpG hypermutation and response to immune checkpoint inhibitors. Overall, our study identified novel cancer types that display somatic CpG hypermutation, strong association with MutSα-deficiency, and potential utility in cancer immunotherapy.
Asunto(s)
Islas de CpG , Reparación de la Incompatibilidad de ADN , Mutación , Neoplasias , Humanos , Reparación de la Incompatibilidad de ADN/genética , Neoplasias/genética , Neoplasias/inmunología , Islas de CpG/genética , Proteína 2 Homóloga a MutS/genética , Proteína 2 Homóloga a MutS/metabolismo , Proteínas de Unión al ADN/genética , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Inhibidores de Puntos de Control Inmunológico/farmacología , Proteína p53 Supresora de Tumor/genéticaRESUMEN
The endonuclease activity of Pms1 directs mismatch repair by generating a nick in the newly replicated DNA strand. Inactivating Pms2, the human homologue of yeast Pms1, increases the chances of colorectal and uterine cancers. Here we use whole genome sequencing to show that loss of this endonuclease activity, via the pms1-DE variant, results in strong mutator effects throughout the Saccharomyces cerevisiae genome. Mutation rates are strongly increased for mutations resulting from all types of single-base substitutions and for a wide variety of single- and multi-base indel mutations. Rates for these events are further increased in strains combining pms1-DE with mutator variants of each of the three major leading and lagging strand replicases. In all cases, mutation rates, spectra, biases, and context preferences are statistically indistinguishable from strains with equivalent polymerases but lacking initial mismatch recognition due to deletion of MSH2. This implies that, across the nuclear genome, strand discrimination via the Pms1 endonuclease is as important for MMR as is initial mismatch recognition by Msh2 heterodimers.
Asunto(s)
Reparación de la Incompatibilidad de ADN , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Reparación de la Incompatibilidad de ADN/genética , Genoma Fúngico , Inestabilidad Genómica/genética , Tasa de Mutación , Proteína 2 Homóloga a MutS/genética , Proteína 2 Homóloga a MutS/metabolismo , Mutación , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Secuenciación Completa del Genoma , Proteínas MutLRESUMEN
Mismatch repair (MMR)-deficient cancer evolves through the stepwise erosion of coding homopolymers in target genes. Curiously, the MMR genes MutS homolog 6 (MSH6) and MutS homolog 3 (MSH3) also contain coding homopolymers, and these are frequent mutational targets in MMR-deficient cancers. The impact of incremental MMR mutations on MMR-deficient cancer evolution is unknown. Here we show that microsatellite instability modulates DNA repair by toggling hypermutable mononucleotide homopolymer runs in MSH6 and MSH3 through stochastic frameshift switching. Spontaneous mutation and reversion modulate subclonal mutation rate, mutation bias and HLA and neoantigen diversity. Patient-derived organoids corroborate these observations and show that MMR homopolymer sequences drift back into reading frame in the absence of immune selection, suggesting a fitness cost of elevated mutation rates. Combined experimental and simulation studies demonstrate that subclonal immune selection favors incremental MMR mutations. Overall, our data demonstrate that MMR-deficient colorectal cancers fuel intratumor heterogeneity by adapting subclonal mutation rate and diversity to immune selection.
Asunto(s)
Neoplasias Colorrectales , Reparación de la Incompatibilidad de ADN , Inestabilidad de Microsatélites , Humanos , Neoplasias Colorrectales/genética , Reparación de la Incompatibilidad de ADN/genética , Proteínas de Unión al ADN/genética , Mutación , Proteína 3 Homóloga de MutS/genética , Tasa de Mutación , Mutación del Sistema de Lectura/genéticaRESUMEN
BACKGROUND: Microsatellite instability (MSI) and mismatch repair (MMR) detection is valuable in assessing prognosis and treatment options. However, the conventional detection methods such as immunohistochemistry (IHC) are limited by not fully consistent results as well as a long turnaround time. TrueMark™ MSI Assay is a novel solution for MSI analysis, but lack of research support in the Chinese colorectal cancer (CRC) patients. MATERIALS AND METHODS: 60 dMMR and 60 pMMR CRC samples identified by IHC were collected and their MSI status were detected using TrueMark™ MSI assay with an expanded panel of 13 markers. The overall performance and diagnostic concordance between TrueMark™ MSI test and MMR IHC analysis were assessed and analyzed. RESULTS: According to the TrueMark™ test, 55 out of the 120 (45.8 %) CRCs were identified as MSI-high (MSI-H) with an instability at ≥ 4/13 markers. Compared with the MMR IHC analysis, an overall percent agreement of 94.2 % and a Kappa of 0.883 were achieved. For the seven inconsistent samples, tumor mutation burden analysis was performed and the results supported the diagnosis by TrueMark™ test. To confirm the robustness of the above findings, a validation was performed in an independent cohort comprising 51 consecutive CRCs. Furthermore, an optimized panel composed of NR-21, NR-24, NR-27, ABI-16, ABI-17 and ABI-20B was developed by multivariate logistic regression model, and showed 100 % agreement with the 13-marker panel for MSI detection in both the derivation and validation sets. CONCLUSION: TrueMark™ MSI provides a fast, reliable and highly automated solution to MSI detection in Chinese CRC patients, and the new 6-marker panel we established shows promise deserving further evaluation.
Asunto(s)
Neoplasias Colorrectales , Inestabilidad de Microsatélites , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Biomarcadores de Tumor/genética , China , Estudios de Cohortes , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/diagnóstico , Reparación de la Incompatibilidad de ADN/genética , Pueblos del Este de Asia , Inmunohistoquímica/métodosRESUMEN
BACKGROUND/AIM: There are no established biomarkers for immune checkpoint inhibitors (ICI) in colorectal cancer (CRC) with microsatellite stability (MSS) or proficient mismatch repair (pMMR). Therefore, this study aimed to identify biomarkers for ICI benefit in patients with pMMR by analyzing the down-regulated DNA repair-related genes involved in highly immunogenic and immune responses, and comparing their expression levels and clinical features. MATERIALS AND METHODS: Mismatch repair (MMR), tumor-infiltrating lymphocytes (TIL), and tumor mutation burden (TMB) were evaluated in 13 CRC cases and mRNA expression levels of 95 DNA repair-related genes were measured. DNA repair-related genes with reduced mRNA expression in the high immunogenicity and high immune response groups were identified. Then, the mRNA expression levels of the identified DNA repair-related genes were measured in 135 patients with CRC. Hierarchical cluster analysis was performed using the mRNA expression levels to compare the clinicopathological characteristics of each cluster. RESULTS: ATR, LIG4, and RAD52 mRNA levels were significantly down-regulated in the high immunogenicity group. GADD45B, SMUG1, and XRCC6 mRNA levels were significantly down-regulated in the high immune response group. Cases in the cluster with reduced mRNA expression of the six genes were pMMR cases. CD8 mRNA expression level was higher in this cluster than in the other clusters. CONCLUSION: Decreased mRNA expression levels of ATR, LIG4, RAD52, GADD45B, SMUG1, and XRCC6 genes were associated with high cytotoxic T cell and TMB levels, suggesting that these genes could serve as biomarkers for ICI efficacy in pMMR cases.
Asunto(s)
Biomarcadores de Tumor , Neoplasias Colorrectales , Reparación del ADN , Linfocitos Infiltrantes de Tumor , Inestabilidad de Microsatélites , Humanos , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/inmunología , Neoplasias Colorrectales/patología , Biomarcadores de Tumor/genética , Femenino , Linfocitos Infiltrantes de Tumor/inmunología , Linfocitos Infiltrantes de Tumor/metabolismo , Masculino , Anciano , Persona de Mediana Edad , Reparación del ADN/genética , Mutación , Reparación de la Incompatibilidad de ADN/genética , Regulación Neoplásica de la Expresión Génica , Adulto , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Inhibidores de Puntos de Control Inmunológico/farmacología , Anciano de 80 o más AñosRESUMEN
Replication repair deficiency (RRD) is a pan-cancer mechanism characterized by abnormalities in the DNA mismatch repair (MMR) system due to pathogenic variants in the PMS2, MSH6, MSH2, or MLH1 genes, and/or in the polymerase-proofreading genes POLE and POLD1. RRD predisposition syndromes (constitutional MMR deficiency, Lynch, and polymerase proofreading-associated polyposis) share overlapping phenotypic and biological characteristics. Moreover, cancers stemming from germline defects of one mechanism can acquire somatic defects in another, leading to complete RRD. Here we describe the recent advances in the diagnostics, surveillance, and clinical management for children with RRD syndromes. For patients with constitutional MMR deficiency, new data combining clinical insights and cancer genomics have revealed genotype-phenotype associations and helped in the development of novel functional assays, diagnostic guidelines, and surveillance recommendations. Recognition of non-gastrointestinal/genitourinary malignancies, particularly aggressive brain tumors, in select children with Lynch and polymerase proofreading-associated polyposis syndromes harboring an RRD biology have led to new management considerations. Additionally, universal hypermutation and microsatellite instability have allowed immunotherapy to be a paradigm shift in the treatment of RRD cancers independent of their germline etiology. These advances have also stimulated a need for expert recommendations about genetic counseling for these patients and their families. Future collaborative work will focus on newer technologies such as quantitative measurement of circulating tumor DNA and functional genomics to tailor surveillance and clinical care, improving immune surveillance; develop prevention strategies; and deliver these novel discoveries to resource-limited settings to maximize benefits for patients globally.
Asunto(s)
Trastornos por Deficiencias en la Reparación del ADN , Humanos , Niño , Trastornos por Deficiencias en la Reparación del ADN/genética , Trastornos por Deficiencias en la Reparación del ADN/diagnóstico , Adulto Joven , Adolescente , Reparación de la Incompatibilidad de ADN/genética , Replicación del ADN/genética , Predisposición Genética a la Enfermedad , Síndromes Neoplásicos Hereditarios/genética , Síndromes Neoplásicos Hereditarios/terapia , Síndromes Neoplásicos Hereditarios/diagnóstico , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/diagnóstico , Neoplasias Colorrectales Hereditarias sin Poliposis/terapia , Inestabilidad de MicrosatélitesRESUMEN
Replication-coupled gene editing using locked nucleic acid-modified single-stranded DNA oligonucleotides (LMOs) can genetically engineer mammalian cells with high precision at single nucleotide resolution. Based on this method, oligonucleotide-directed mutation screening (ODMS) was developed to determine whether variants of uncertain clinical significance of DNA mismatch repair (MMR) genes can cause Lynch syndrome. In ODMS, the appearance of 6-thioguanine-resistant colonies upon introduction of the variant is indicative for defective MMR and hence pathogenicity. Whereas mouse embryonic stem cells (mESCs) hemizygous for MMR genes were used previously, we now show that ODMS can also be applied in wild-type mESCs carrying two functional alleles of each MMR gene. 6-Thioguanine resistance can result from two possible events: first, the mutation is present in only one allele, which is indicative for dominant-negative activity of the variant; and second, both alleles contain the planned modification, which is indicative for a regular loss-of-function variant. Thus, ODMS in wild-type mESCs can discriminate fully disruptive and dominant-negative MMR variants. The feasibility of biallelic targeting suggests that the efficiency of LMO-mediated gene targeting at a nonselectable locus may be enriched in cells that had undergone a simultaneous selectable LMO targeting event. This turned out to be the case and provided a protocol to improve recovery of LMO-mediated gene modification events.
Asunto(s)
Alelos , Reparación de la Incompatibilidad de ADN , Edición Génica , Reparación de la Incompatibilidad de ADN/genética , Edición Génica/métodos , Ratones , Animales , Células Madre Embrionarias de Ratones/metabolismo , Humanos , Proteína 2 Homóloga a MutS/genética , Mutación con Pérdida de Función , Replicación del ADN/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Proteína 3 Homóloga de MutS/genética , Mutación , Genes Dominantes , Proteínas de Unión al ADNRESUMEN
Mutations accumulate in the genome of every cell of the body throughout life, causing cancer and other diseases1,2. Most mutations begin as nucleotide mismatches or damage in one of the two strands of the DNA before becoming double-strand mutations if unrepaired or misrepaired3,4. However, current DNA-sequencing technologies cannot accurately resolve these initial single-strand events. Here we develop a single-molecule, long-read sequencing method (Hairpin Duplex Enhanced Fidelity sequencing (HiDEF-seq)) that achieves single-molecule fidelity for base substitutions when present in either one or both DNA strands. HiDEF-seq also detects cytosine deamination-a common type of DNA damage-with single-molecule fidelity. We profiled 134 samples from diverse tissues, including from individuals with cancer predisposition syndromes, and derive from them single-strand mismatch and damage signatures. We find correspondences between these single-strand signatures and known double-strand mutational signatures, which resolves the identity of the initiating lesions. Tumours deficient in both mismatch repair and replicative polymerase proofreading show distinct single-strand mismatch patterns compared to samples that are deficient in only polymerase proofreading. We also define a single-strand damage signature for APOBEC3A. In the mitochondrial genome, our findings support a mutagenic mechanism occurring primarily during replication. As double-strand DNA mutations are only the end point of the mutation process, our approach to detect the initiating single-strand events at single-molecule resolution will enable studies of how mutations arise in a variety of contexts, especially in cancer and ageing.
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Disparidad de Par Base , Daño del ADN , ADN de Cadena Simple , Análisis de Secuencia de ADN , Imagen Individual de Molécula , Humanos , Envejecimiento/genética , Desaminasas APOBEC/genética , Desaminasas APOBEC/metabolismo , Disparidad de Par Base/genética , Citidina Desaminasa/metabolismo , Citidina Desaminasa/genética , Citosina/metabolismo , Desaminación , Daño del ADN/genética , Reparación de la Incompatibilidad de ADN/genética , Replicación del ADN/genética , ADN de Cadena Simple/genética , Genoma Mitocondrial/genética , Mutación , Neoplasias/genética , Análisis de Secuencia de ADN/métodos , Análisis de Secuencia de ADN/normas , Imagen Individual de Molécula/métodos , Masculino , FemeninoRESUMEN
Gastric cancer (GC) is a common malignancy that presents challenges in patient care worldwide. The mismatch repair (MMR) system is a highly conserved DNA repair mechanism that protects genome integrity during replication. Deficient MMR (dMMR) results in an increased accumulation of genetic errors in microsatellite sequences, leading to the development of a microsatellite instability-high (MSI-H) phenotype. Most MSI-H/dMMR GCs arise sporadically, mainly due to MutL homolog 1 (MLH1) epigenetic silencing. Unlike microsatellite-stable (MSS)/proficient MMR (pMMR) GCs, MSI-H/dMMR GCs are relatively rare and represent a distinct subtype with genomic instability, a high somatic mutational burden, favorable immunogenicity, different responses to treatment, and prognosis. dMMR/MSI-H status is a robust predictive biomarker for treatment with immune checkpoint inhibitors (ICIs) due to high neoantigen load, prominent tumor-infiltrating lymphocytes, and programmed cell death ligand 1 (PD-L1) overexpression. However, a subset of MSI-H/dMMR GC patients does not benefit from immunotherapy, highlighting the need for further research into predictive biomarkers and resistance mechanisms. This review provides a comprehensive overview of the clinical, molecular, immunogenic, and therapeutic aspects of MSI-H/dMMR GC, with a focus on the impact of ICIs in immunotherapy and their potential as neoadjuvant therapies. Understanding the complexity and diversity of the molecular and immunological profiles of MSI-H/dMMR GC will drive the development of more effective therapeutic strategies and molecular targets for future precision medicine.
Asunto(s)
Reparación de la Incompatibilidad de ADN , Inestabilidad de Microsatélites , Neoplasias Gástricas , Humanos , Neoplasias Gástricas/genética , Neoplasias Gástricas/terapia , Neoplasias Gástricas/patología , Reparación de la Incompatibilidad de ADN/genética , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Biomarcadores de Tumor/genética , PronósticoRESUMEN
BACKGROUND: Sn1-type alkylating agents methylate the oxygen atom on guanine bases thereby producing O6-methylguanine. This modified base could pair with thymine and cytosine, resulting in the formation of O6-methylguanine/thymine mismatch during DNA replication, recognized by the mismatch repair (MMR) complex, which then initiates the DNA damage response and subsequent apoptotic processes. In our investigation of the molecular mechanisms underlying MMR-dependent apoptosis, we observed FANCD2 modification upon the activity of alkylating agent N-methyl-N-nitrosourea (MNU). This observation led us to hypothesize a relevant role for FANCD2 in the apoptosis induction process. METHODS AND RESULTS: We generated FANCD2 knockout cells using the CRISPR/Cas9 method in the human cervical cancer cell line HeLa MR. FANCD2-deficient cells exhibited MNU hypersensitivity. Upon MNU exposure, FANCD2 colocalized with the MMR complex. MNU-treated FANCD2 knockout cells displayed severe S phase delay followed by increased G2/M arrest and MMR-dependent apoptotic cell death. Moreover, FANCD2 knockout cells exhibited impaired CtIP and RAD51 recruitment to the damaged chromatin and DNA double-strand break accumulation, indicated by simultaneously observed increased γH2AX signal and 53BP1 foci. CONCLUSIONS: Our data suggest that FANCD2 is crucial for recruiting homologous recombination factors to the sites of the MMR-dependent replication stress to resolve the arrested replication fork and counteract O6-methylguanine-triggered MMR-dependent apoptosis.
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Apoptosis , Reparación de la Incompatibilidad de ADN , Proteína del Grupo de Complementación D2 de la Anemia de Fanconi , Guanina , Humanos , Reparación de la Incompatibilidad de ADN/genética , Proteína del Grupo de Complementación D2 de la Anemia de Fanconi/metabolismo , Proteína del Grupo de Complementación D2 de la Anemia de Fanconi/genética , Apoptosis/genética , Apoptosis/efectos de los fármacos , Guanina/metabolismo , Guanina/análogos & derivados , Células HeLa , Daño del ADN , Metilnitrosourea/toxicidad , Sistemas CRISPR-Cas , Técnicas de Inactivación de Genes , Recombinasa Rad51/metabolismo , Recombinasa Rad51/genética , Replicación del ADN/efectos de los fármacos , Replicación del ADN/genéticaRESUMEN
Patients with Lynch syndrome, one of the most common hereditary tumor predisposition syndromes, harbor an increased risk for a broad spectrum of especially gastrointestinal and gynecological tumors. Causative for the syndrome are variants in DNA mismatch repair genes, which are passed on to the offspring at a 50% chance (autosomal dominant inheritance). The tumor tissue of these patients usually shows microsatellite instability, which is of increasing relevance regarding prognosis and therapeutic decisions. The detection of a causative genetic variant in a patient enables predictive testing of family members to provide relief to noncarriers and provide carriers with intensified risk-adapted surveillance. In addition, chemoprevention with aspirin (acetylsalicylic acid) has been proven useful for chemoprevention in studies. Therefore, the diagnosis of Lynch syndrome is important for patients and their relatives.
Asunto(s)
Neoplasias Colorrectales Hereditarias sin Poliposis , Humanos , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/diagnóstico , Femenino , Reparación de la Incompatibilidad de ADN/genética , Inestabilidad de Microsatélites , Aspirina/uso terapéutico , Predisposición Genética a la EnfermedadRESUMEN
Endometrial cancer (EC) accounts for 90% of uterine cancer cases. It is considered not only one of the most common gynecological malignancies but also one of the most frequent cancers among women overall. Nowadays, the differentiation of EC subtypes is based on immunohistochemistry and molecular techniques. It is considered that patients' prognosis and the implementation of the appropriate treatment depend on the cancer subtype. Patients with pathogenic variants in POLE have the most favorable outcome, while those with abnormal p53 protein have the poorest. Therefore, in patients with POLE mutation, the de-escalation of postoperative treatment may be considered, and patients with abnormal p53 protein should be subjected to intensive adjuvant therapy. Patients with a DNA mismatch repair (dMMR) deficiency are classified in the intermediate prognosis group as EC patients without a specific molecular profile. Immunotherapy has been recognized as an effective treatment method in patients with advanced or recurrent EC with a mismatch deficiency. Thus, different adjuvant therapy approaches, including targeted therapy and immunotherapy, are being proposed depending on the EC subtype, and international guidelines, such as those published by ESMO and ESGO/ESTRO/ESP, include recommendations for performing the molecular classification of all EC cases. The decision about adjuvant therapy selection has to be based not only on clinical data and histological type and stage of cancer, but, following international recommendations, has to include EC molecular subtyping. This review describes how molecular classification could support more optimal therapeutic management in endometrial cancer patients.
Asunto(s)
Neoplasias Endometriales , Humanos , Neoplasias Endometriales/genética , Neoplasias Endometriales/clasificación , Neoplasias Endometriales/patología , Neoplasias Endometriales/terapia , Neoplasias Endometriales/metabolismo , Femenino , Inmunoterapia/métodos , Mutación , Reparación de la Incompatibilidad de ADN/genética , Pronóstico , Biomarcadores de Tumor/genéticaRESUMEN
Deficiencies in DNA mismatch repair (MMRd) leave characteristic footprints of microsatellite instability (MSI) in cancer genomes. We used data from the Cancer Genome Atlas and International Cancer Genome Consortium to conduct a comprehensive analysis of MSI-associated cancers, focusing on indel mutational signatures. We classified MSI-high genomes into two subtypes based on their indel profiles: deletion-dominant (MMRd-del) and insertion-dominant (MMRd-ins). Compared with MMRd-del genomes, MMRd-ins genomes exhibit distinct mutational and transcriptomic features, including a higher prevalence of T>C substitutions and related mutation signatures. Short insertions and deletions in MMRd-ins and MMRd-del genomes target different sets of genes, resulting in distinct indel profiles between the two subtypes. In addition, indels in the MMRd-ins genomes are enriched with subclonal alterations that provide clues about a distinct evolutionary relationship between the MMRd-ins and MMRd-del genomes. Notably, the transcriptome analysis indicated that MMRd-ins cancers upregulate immune-related genes, show a high level of immune cell infiltration, and display an elevated neoantigen burden. The genomic and transcriptomic distinctions between the two types of MMRd genomes highlight the heterogeneity of genetic mechanisms and resulting genomic footprints and transcriptomic changes in cancers, which has potential clinical implications.
Asunto(s)
Reparación de la Incompatibilidad de ADN , Mutación INDEL , Inestabilidad de Microsatélites , Neoplasias , Humanos , Neoplasias/genética , Neoplasias/inmunología , Reparación de la Incompatibilidad de ADN/genética , Genoma Humano , Transcriptoma/genéticaRESUMEN
Fifteen percent of all colorectal cancers have detectable defects in the mismatch repair system (dMMR). MMR status is used to identify possible Lynch Syndrome (LS) and to determine prognosis and choice of treatment. Two standard techniques for determining MMR status are immunohistochemistry (IHC) and analysis for microsatellite instability (MSI) by PCR. Recently, our department introduced Idylla™ MSI assay as an alternative option to IHC, and as part of this, we introduced a decision algorithm. The purpose of this study was to review the use of the new method and our algorithm and to assess possible false-positive results. Retrospectively, we identified 629 cases of colorectal cancer in which either IHC (336 cases) or Idylla™ MSI (293 cases) was performed. Similar results were obtained by the two methods. IHC detected dMMR in 55 cases (16%) and Idylla™ MSI in 52 cases (18%). In all 52 cases of MSI, subsequent IHC was performed. One case was not confirmed by IHC, but was confirmed by another PCR-based method. Overall, we found that the Idylla™ MSI works well as a screening method for dMMR with no false-positive cases detected. The proposed algorithm was useful and easily applicable.
Asunto(s)
Algoritmos , Neoplasias Colorrectales , Inmunohistoquímica , Inestabilidad de Microsatélites , Humanos , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/patología , Estudios Retrospectivos , Masculino , Femenino , Inmunohistoquímica/métodos , Persona de Mediana Edad , Anciano , Reparación de la Incompatibilidad de ADN/genética , Adulto , Anciano de 80 o más Años , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/diagnóstico , Reacción en Cadena de la Polimerasa/métodosRESUMEN
BACKGROUND: The optimal interval of colonoscopy (CS) surveillance in cases with Lynch syndrome (LS), and stratification according to the causative mismatch repair gene mutation, has received much attention. To verify a feasible and effective CS surveillance strategy, we investigated the colorectal cancer (CRC) incidence at different intervals and the characteristics of precancerous colorectal lesions of LS cases. METHODS: This retrospective multicenter study was conducted in Japan. CRCs and advanced adenomas (AAs) in 316 LS cases with germline pathogenic variants (path_) were analyzed according to the data of 1,756 registered CS. RESULTS: The mean time interval for advanced CRCs (ACs) detected via CS surveillance was 28.7 months (95% confidence interval: 13.8-43.5). The rate of AC detection within (2.1%) and beyond 2 years (8.7%) differed significantly (p = 0.0003). AAs accounted for 43%, 46%, and 41% of lesions < 10 mm in size in the MLH1-, MSH2-, and MSH6-groups, respectively. The lifetime incidence of metachronous CRCs requiring intestinal resection for path_MLH1, path_MSH2, and path_MSH6 cases was 34%, 23%, and 14% in these cases, respectively. The cumulative CRC incidence showed a trend towards a 10-year delay for path_MSH6 cases as compared with that for path_MLH1 and path_MSH2 cases. CONCLUSIONS: In cases with path_MLH1, path_MSH2, and path_MSH6, maintaining an appropriate CS surveillance interval of within 2 years is advisable to detect of the colorectal lesion amenable to endoscopic treatment. path_MSH6 cases could be stratified with path_MLH1 and MSH2 cases in terms of risk of metachronous CRC and age of onset.