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1.
Mol Cell ; 68(4): 797-807.e7, 2017 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-29149600

RESUMO

DNA lesions caused by UV damage are thought to be repaired solely by the nucleotide excision repair (NER) pathway in human cells. Patients carrying mutations within genes functioning in this pathway display a range of pathologies, including an increased susceptibility to cancer, premature aging, and neurological defects. There are currently no curative therapies available. Here we performed a high-throughput chemical screen for agents that could alleviate the cellular sensitivity of NER-deficient cells to UV-induced DNA damage. This led to the identification of the clinically approved anti-diabetic drug acetohexamide, which promoted clearance of UV-induced DNA damage without the accumulation of chromosomal aberrations, hence promoting cellular survival. Acetohexamide exerted this protective function by antagonizing expression of the DNA glycosylase, MUTYH. Together, our data reveal the existence of an NER-independent mechanism to remove UV-induced DNA damage and prevent cell death.


Assuntos
Dano ao DNA , DNA Glicosilases/metabolismo , Reparo do DNA/efeitos da radiação , Raios Ultravioleta , Acetoexamida/farmacologia , Linhagem Celular Tumoral , DNA Glicosilases/biossíntese , DNA Glicosilases/genética , Reparo do DNA/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/efeitos da radiação , Humanos , Masculino
2.
Oncologist ; 29(2): e213-e223, 2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-37589222

RESUMO

The aim of this study was to determine the pan-cancer landscape of MUTYH alterations and the relationship between MUTYH mutations and potentially actionable biomarkers such as specific genomic alterations, tumor mutational burden, and mutational signatures. We used a large pan-cancer comprehensive genomic dataset from patients profiled (tissue next generation sequencing) during routine clinical care. Overall, 2.8% of 229 120 solid tumors had MUTYH alterations, of which 55% were predicted germline. Thirty tumor types had a 2% or greater MUTYH mutation rate. MUTYH-altered versus -WT cancers had significantly higher tumor mutational burden and more frequent alterations in KRAS G12C, but not in KRAS in general; these observations were statistically significant, especially in colorectal cancers. Across cancers, PD-L1 expression levels (immunohistochemistry) were not associated with MUTYH alteration status. In silico computation demonstrated that MUTYH mutational signatures are associated with higher levels of hydrophobicity (which may reflect higher immunogenicity of neoantigens) relative to several other signature types such as microsatellite instability. Survival of patients with MUTYH-altered versus -WT tumors was similar. In conclusion, comprehensive genomic profiling suggests that several features of MUTYH-altered cancers may be pharmacologically targetable. Drugs such as sotorasib (targeting KRAS G12C) and immune checkpoint inhibitors, targeting the increased mutational load and higher neo-antigen hydrophobicity/immunogenicity merit investigation in MUTYH-mutated malignancies.


Assuntos
Neoplasias , Proteínas Proto-Oncogênicas p21(ras) , Humanos , Mutação , Taxa de Mutação , Neoplasias/genética , Prevalência , Proteínas Proto-Oncogênicas p21(ras)/genética
3.
Breast Cancer Res Treat ; 204(1): 151-158, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38062336

RESUMO

PURPOSE: Breast cancer patients referred to genetic counseling often undergo genetic testing with broad panels that include both breast cancer susceptibility genes as well as genes more specific for extramammary sites. As a result, patients are often incidentally found to have germline mutations in genes that are not necessarily related to breast cancer risk. One such gene is MUTYH. To understand the role MUTYH may play in breast cancer, the clinicopathological features of patients with monoallelic MUTYH germline mutation and breast cancer were examined. METHODS: The clinicopathological characteristics of the breast cancers from patients with monoallelic MUTYH mutation were compared to breast cancer patients with other germline mutations in known breast cancer susceptibility genes, including ATM, BRCA1/2, CHEK2, and PALB2. The breast cancer patients who received genetic counseling but tested negative for the aforementioned gene mutations were used as a control group. RESULTS: Histologic characteristics of the breast cancers arising in monoallelic MUTYH mutation carriers had significantly larger tumor size, higher tumor grade, and more high-risk biomarker profiles (i.e., Her2-positive and triple-negative) than breast cancer patients with susceptibility genes, except for BRCA1. MUTYH mutation carriers also showed a trend of more frequent intratumoral divergency in terms of tumor grade and biomarker profiles. CONCLUSION: Although germline monoallelic MUTYH mutation is not thought to confer a meaningfully increased risk of breast cancer development, it may contribute to pathological aggressiveness and diversity of breast cancers when they sporadically arise in MUTYH carriers.


Assuntos
Neoplasias da Mama , Feminino , Humanos , Biomarcadores , Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Mutação
4.
Proc Natl Acad Sci U S A ; 118(36)2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34479993

RESUMO

Neuroblastomas are childhood tumors with frequent fatal relapses after induction treatment, which is related to tumor evolution with additional genomic events. Our whole-genome sequencing data analysis revealed a high frequency of somatic cytosine > adenine (C > A) substitutions in primary neuroblastoma tumors, which was associated with poor survival. We showed that increased levels of C > A substitutions correlate with copy number loss (CNL) of OGG1 or MUTYH Both genes encode DNA glycosylases that recognize 8-oxo-guanine (8-oxoG) lesions as a first step of 8-oxoG repair. Tumor organoid models with CNL of OGG1 or MUTYH show increased 8-oxoG levels compared to wild-type cells. We used CRISPR-Cas9 genome editing to create knockout clones of MUTYH and OGG1 in neuroblastoma cells. Whole-genome sequencing of single-cell OGG1 and MUTYH knockout clones identified an increased accumulation of C > A substitutions. Mutational signature analysis of these OGG1 and MUTYH knockout clones revealed enrichment for C > A signatures 18 and 36, respectively. Clustering analysis showed that the knockout clones group together with tumors containing OGG1 or MUTYH CNL. In conclusion, we demonstrate that defects in 8-oxoG repair cause accumulation of C > A substitutions in neuroblastoma, which contributes to mutagenesis and tumor evolution.


Assuntos
Reparo do DNA/genética , Guanosina/análogos & derivados , Neuroblastoma/genética , Adenina/metabolismo , Criança , Citosina/metabolismo , Dano ao DNA , DNA Glicosilases/genética , DNA Glicosilases/metabolismo , Feminino , Guanina/metabolismo , Guanosina/genética , Guanosina/metabolismo , Humanos , Masculino , Mutagênese , Recidiva Local de Neoplasia/genética , Neuroblastoma/metabolismo , Estresse Oxidativo , Polimorfismo de Nucleotídeo Único/genética
5.
Molecules ; 29(12)2024 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-38930820

RESUMO

The genome-the source of life and platform of evolution-is continuously exposed to harmful factors, both extra- and intra-cellular. Their activity causes different types of DNA damage, with approximately 80 different types of lesions having been identified so far. In this paper, the influence of a clustered DNA damage site containing imidazolone (Iz) or oxazolone (Oz) and 7,8-dihydro-8-oxo-2'-deoxyguanosine (OXOdG) on the charge transfer through the double helix as well as their electronic properties were investigated. To this end, the structures of oligo-Iz, d[A1Iz2A3OXOG4A5]*d[T5C4T3C2T1], and oligo-Oz, d[A1Oz2A3OXOG4A5]*d[T5C4T3C2T1], were optimized at the M06-2X/6-D95**//M06-2X/sto-3G level of theory in the aqueous phase using the ONIOM methodology; all the discussed energies were obtained at the M06-2X/6-31++G** level of theory. The non-equilibrated and equilibrated solvent-solute interactions were taken into consideration. The following results were found: (A) In all the discussed cases, OXOdG showed a higher predisposition to radical cation formation, and B) the excess electron migration toward Iz and Oz was preferred. However, in the case of oligo-Oz, the electron transfer from Oz2 to complementary C4 was noted during vertical to adiabatic anion relaxation, while for oligo-Iz, it was settled exclusively on the Iz2 moiety. The above was reflected in the charge transfer rate constant, vertical/adiabatic ionization potential, and electron affinity energy values, as well as the charge and spin distribution. It can be postulated that imidazolone moiety formation within the CDL ds-oligo structure and its conversion to oxazolone can significantly influence the charge migration process, depending on the C2 carbon hybridization sp2 or sp3. The above can confuse the single DNA damage recognition and removal processes, cause an increase in mutagenesis, and harm the effectiveness of anticancer therapy.


Assuntos
Dano ao DNA , Imidazóis , Imidazóis/química , Oxazolona/química , 8-Hidroxi-2'-Desoxiguanosina/química , DNA/química , Modelos Moleculares , Desoxiguanosina/química , Desoxiguanosina/análogos & derivados , Termodinâmica
6.
Neuropathol Appl Neurobiol ; 49(4): e12929, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37524406

RESUMO

AIMS: The mutY DNA glycosylase encoded by the MUTYH gene prevents G:C → T:A transversions through the base excision repair DNA repair system. Germline biallelic pathogenic variants in MUTYH cause an adenomatous polyposis called MUTYH-associated polyposis (MAP), an autosomal recessive disease (OMIM: 608456), with an increased risk of colorectal cancer. Digestive lesions in this context show an excess of G:C → T:A transversions, individualising a specific mutational signature associated with MUTYH deficiency called signature SBS36. Predisposition to other tumours in patients with germline biallelic pathogenic variants in MUTYH is suspected but remains unclear. We report the first case of medulloblastoma in a patient with MAP, carrying the homozygous pathogenic variant c.1227_1228dup, p.(Glu410Glyfs*43) in MUTYH. METHODS: Whole exome sequencing was performed on the medulloblastoma to enlighten single nucleotide variants of interest, microsatellite status and mutational signature. The objective was to determine the involvement of MUTYH deficiency in the oncogenesis of this medulloblastoma. RESULTS: The medulloblastoma has the mutational signature SBS36 and driver pathogenic variants in CTNNB1, PTCH1 and KDM6A corresponding to G:C → T:A transversions, suggesting a role of MUTYH deficiency in oncogenesis. CONCLUSIONS: Therefore, medulloblastoma could be a rare manifestation associated with germline biallelic pathogenic variants in MUTYH.


Assuntos
Polipose Adenomatosa do Colo , Neoplasias Cerebelares , Neoplasias Colorretais , Meduloblastoma , Humanos , Meduloblastoma/genética , Predisposição Genética para Doença , Polipose Adenomatosa do Colo/genética , Polipose Adenomatosa do Colo/patologia , Mutação , Neoplasias Cerebelares/genética , Carcinogênese , Neoplasias Colorretais/genética
7.
J Pathol ; 256(2): 214-222, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34816434

RESUMO

MUTYH encodes a glycosylase involved in the base excision repair of DNA. Biallelic pathogenic germline variants in MUTYH cause an autosomal recessive condition known as MUTYH-associated adenomatous polyposis and consequently increase the risk of colorectal cancer. However, reports of increased cancer risk in individuals carrying only one defective MUTYH allele are controversial and based on studies involving few individuals. Here, we describe a comprehensive investigation of monoallelic pathogenic MUTYH germline variants in 10,389 cancer patients across 33 different tumour types and 117,000 healthy individuals. Our results indicate that monoallelic pathogenic MUTYH germline variants can lead to tumorigenesis through a mechanism of somatic loss of heterozygosity of the functional MUTYH allele in the tumour. We confirmed that the frequency of monoallelic pathogenic MUTYH germline variants is higher in individuals with cancer than in the general population, although this frequency is not homogeneous among tumour types. We also demonstrated that the MUTYH mutational signature is present only in tumours with loss of the functional allele and found that the characteristic MUTYH base substitution (C>A) increases stop-codon generation. We identified key genes that are affected during tumorigenesis. In conclusion, we propose that carriers of the monoallelic pathogenic MUTYH germline variant are at a higher risk of developing tumours, especially those with frequent loss of heterozygosity events, such as adrenal adenocarcinoma, although the overall risk is still low. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.


Assuntos
Biomarcadores Tumorais/genética , Transformação Celular Neoplásica/genética , DNA Glicosilases/genética , Mutação em Linhagem Germinativa , Neoplasias/genética , Estudos de Casos e Controles , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Bases de Dados Genéticas , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Perda de Heterozigosidade , Neoplasias/enzimologia , Neoplasias/patologia , Fenótipo , Prognóstico , Medição de Risco , Fatores de Risco
8.
J Genet Couns ; 32(2): 342-350, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36245263

RESUMO

Germline genetic testing for inherited cancer risk is increasingly being performed with multigene panel testing with MUTYH often included on colorectal cancer- and polyposis-focused panels, as well as on broader pan-cancer panels. With up to 1%-2% of the general population being monoallelic MUTYH carriers, pathogenic/likely pathogenic (P/LP) variants in MUTYH are one of the most common findings on multigene cancer panels. However, little is known about patient experience and understanding of monoallelic MUTYH P/LP variants, nor whether such findings influence medical management recommendations and familial communication, which this study aims to better understand. Monoallelic P/LP MUTYH carriers were recruited from the Prospective Registry of Multiplex Testing (PROMPT) and completed a cross-sectional self-report survey on sociodemographic characteristics, medical and family history, experiences with MUTYH genetic testing, genetics and MUTYH knowledge, perceived cancer risk, and familial communication. Of 115 eligible PROMPT participants, 49 (43%) completed the survey who were primarily female (94%), white (96%), had a history of cancer (61%), and a median age of 51.4 years. Most participants (61%) reported satisfaction with how their healthcare provider managed their genetic test result and care, and 65% of survey participants reported their provider recommended colonoscopy based on their genetic test results. Participants' responses also reflected variable levels of knowledge regarding cancer risks and screening recommendations for MUTYH carriers. The majority (98%) of participants shared their genetic test results with at least some of their relatives; however, only 13% of eligible relatives reportedly underwent cascade testing. Taken together, this study provides needed insight into the overall experiences of monoallelic MUTYH carriers and highlights numerous areas for improvement in clinician education, communication, and management of these individuals.


Assuntos
Neoplasias Colorretais , Feminino , Humanos , Pessoa de Meia-Idade , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Estudos Transversais , Predisposição Genética para Doença , Testes Genéticos , Heterozigoto , Mutação
9.
Genes Chromosomes Cancer ; 61(10): 622-628, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35545820

RESUMO

There is growing body of evidence supporting the role of germline mutations in the pathogenesis of pediatric central nervous system (CNS) tumors, and the widespread use of next-generation sequencing (NGS) panels facilitates their detection. Variants of the MUTYH gene are increasingly recognized as suspected germline background of various extraintestinal malignancies, besides their well-characterized role in the polyposis syndrome associated with biallelic mutations. Using a multigene NGS panel (Illumina TruSight Oncology 500), we detected one H3 G34V- and one H3 K27M-mutant pediatric high-grade diffuse glioma, in association with c.1178G>A (p.G393D) and c.916C>T (p.R306C) MUTYH variants, respectively. Both MUTYH mutations were germline, heterozygous and inherited, according to the subsequent genetic testing of the patients and their first-degree relatives. In the H3 K27M-mutant glioma, amplifications affecting the 4q12 region were also detected, in association with KDR-PDGFRA, KIT-PDGFRA, and KDR-CHIC2 fusions, previously unreported in this entity. Among 47 other CNS tumors of various histological types tested with the same NGS panel in our institution, only one adult glioblastoma harbored MUTYH mutation. Together with a single previous report, our data raises the possibility of an association between germline MUTYH mutations and CNS malignancies, particularly in pediatric histone H3-mutant gliomas.


Assuntos
Neoplasias Encefálicas , Neoplasias do Sistema Nervoso Central , DNA Glicosilases , Glioma , Adulto , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Criança , DNA Glicosilases/genética , Mutação em Linhagem Germinativa , Glioma/genética , Glioma/patologia , Humanos
10.
J Biol Chem ; 295(11): 3692-3707, 2020 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-32001618

RESUMO

Higher expression of the human DNA repair enzyme MUTYH has previously been shown to be strongly associated with reduced survival in a panel of 24 human lymphoblastoid cell lines exposed to the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The molecular mechanism of MUTYH-enhanced MNNG cytotoxicity is unclear, because MUTYH has a well-established role in the repair of oxidative DNA lesions. Here, we show in mouse embryonic fibroblasts (MEFs) that this MNNG-dependent phenotype does not involve oxidative DNA damage and occurs independently of both O6-methyl guanine adduct cytotoxicity and MUTYH-dependent glycosylase activity. We found that blocking of abasic (AP) sites abolishes higher survival of Mutyh-deficient (Mutyh-/-) MEFs, but this blockade had no additive cytotoxicity in WT MEFs, suggesting the cytotoxicity is due to MUTYH interactions with MNNG-induced AP sites. We found that recombinant mouse MUTYH tightly binds AP sites opposite all four canonical undamaged bases and stimulated apurinic/apyrimidinic endonuclease 1 (APE1)-mediated DNA incision. Consistent with these observations, we found that stable expression of WT, but not catalytically-inactive MUTYH, enhances MNNG cytotoxicity in Mutyh-/- MEFs and that MUTYH expression enhances MNNG-induced genomic strand breaks. Taken together, these results suggest that MUTYH enhances the rapid accumulation of AP-site intermediates by interacting with APE1, implicating MUTYH as a factor that modulates the delicate process of base-excision repair independently of its glycosylase activity.


Assuntos
Alquilantes/toxicidade , DNA Glicosilases/metabolismo , Reparo do DNA , Metilnitronitrosoguanidina/toxicidade , Animais , Sequência de Bases , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Reagentes de Ligações Cruzadas/metabolismo , DNA/metabolismo , Dano ao DNA , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Fibroblastos/metabolismo , Guanina/análogos & derivados , Guanina/metabolismo , Humanos , Cinética , Camundongos , Modelos Biológicos , Proteínas Mutantes/metabolismo , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Proteínas Recombinantes/metabolismo , Bases de Schiff/metabolismo
11.
Breast Cancer Res Treat ; 188(1): 295-305, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33942220

RESUMO

BACKGROUND: Breast cancer (BC) is the most common cancer in women. In contrast, male BC is about 100 times less common than in women, being considered a rare disease. Male BC may be a distinctive subtype of BC and available data seems to indicate that male BC has a higher dependence on genetic variants than female BC. Nevertheless, the same prognostic and predictive markers are used to determine optimal management strategies for both male and female BC. Several studies have assessed the role of genetic polymorphisms (SNPs) in DNA repair genes in female BC susceptibility. However, data on male BC is scarce. Thus, the current study aimed to assess the role of SNPs in XRCC1, MUTYH and TP53 genes in a male cohort of BC, and, in addition, compare the male data with matched results previously genotyped in female BC patients. METHODS: The male BC cohort was genotyped through Real-Time PCR using TaqMan Assays for several SNPs previously analysed in Portuguese female BC patients. RESULTS: The results obtained indicate significant differences in BC susceptibility between males and females for the XRCC1 rs1799782, MUTYH rs3219489 and TP53 rs1042522 and rs8064946 variants. CONCLUSIONS: In males, XRCC1 and TP53 variants, when in heterozygosity, seem to be related with lower susceptibility for BC, contrasting with higher susceptibility for a MUTYH variant in females. These findings may help to explain the difference in incidence of BC between the two sexes.


Assuntos
Neoplasias da Mama Masculina/genética , DNA Glicosilases/genética , Proteína Supressora de Tumor p53/genética , Proteína 1 Complementadora Cruzada de Reparo de Raio-X/genética , Neoplasias da Mama , Estudos de Casos e Controles , Estudos de Coortes , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Polimorfismo de Nucleotídeo Único
12.
Int J Colorectal Dis ; 36(10): 2199-2204, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34244858

RESUMO

PURPOSE: The carrier frequency of MUTYH pathogenic variants in the population may be as high as one in 45. Some studies have found an increased risk of colorectal cancer (CRC) in monoallelic carriers of MUTYH pathogenic variants, but the role of early surveillance colonoscopy is not conclusive. This study aimed to assess the outcomes of colonoscopy surveillance in MUTYH carriers. METHODS: Patients, with a monoallelic pathogenic variant in MUTYH, found at cascade testing, were identified from the St Mark's Hospital Polyposis Registry database. Findings at surveillance colonoscopy were reviewed. RESULTS: Two hundred and forty-nine carriers were identified, of whom 125 had undergone at least one surveillance colonoscopy. Twenty-eight patients (22%) developed at least one adenoma; all adenomas had low-grade dysplasia (LGD). The median age at first colonoscopy was 36 years (range 16-75 years). The median age at first adenoma detection was 43 years (range 22-75 years). The cumulative incidence of adenoma development by age 30, 40, 50, 60 and 70 years was 3.2%, 8.8%, 15.2%, 18.4% and 20.8%, respectively. No CRCs were observed. CONCLUSIONS: Our cohort of monoallelic carriers of MUTYH pathogenic variants is a relatively younger group than adults entering population screening colonoscopy, but a high adenoma rate was not observed. No CRCs were detected, suggesting that current guidance that these individuals should be managed in the same way as the general population is reasonable.


Assuntos
Adenoma , Polipose Adenomatosa do Colo , Neoplasias Colorretais , DNA Glicosilases , Adenoma/epidemiologia , Adenoma/genética , Adolescente , Adulto , Idoso , Neoplasias Colorretais/genética , DNA Glicosilases/genética , Heterozigoto , Humanos , Pessoa de Meia-Idade , Mutação , Adulto Jovem
13.
Artigo em Inglês | MEDLINE | ID: mdl-32615015

RESUMO

We describe a family severely affected by colorectal cancer (CRC) where whole-exome sequencing identified the coinheritance of the germline variants encoding MSH6 p.Thr1100Met and MUTYH p.Tyr179Cys in, at least, three CRC patients diagnosed before 60 years of age. Digenic inheritance of monoallelic MSH6 variants of uncertain significance and MUTYH variants has been suggested to predispose to Lynch syndrome-associated cancers; however, cosegregation with disease in the familial setting has not yet been established. The identification of individuals carrying multiple potential cancer risk variants is expected to rise with the increased application of whole-genome sequencing and large multigene panel testing in clinical genetic counseling of familial cancer patients. Here we demonstrate the coinheritance of monoallelic variants in MSH6 and MUTYH consistent with cosegregation with CRC, further supporting a role for digenic inheritance in cancer predisposition.

14.
Gut ; 69(7): 1283-1293, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-31744909

RESUMO

OBJECTIVE: Familial adenomatous polyposis (FAP) is characterised by the development of hundreds to thousands of adenomas at different evolutionary stages in the colon and rectum that will inevitably progress to adenocarcinomas if left untreated. Here, we investigated the genetic alterations and transcriptomic transitions from precancerous adenoma to carcinoma. DESIGN: Whole-exome sequencing, whole-genome sequencing and single-cell RNA sequencing were performed on matched adjacent normal tissues, multiregionally sampled adenomas at different stages and carcinomas from six patients with FAP and one patient with MUTYH-associated polyposis (n=56 exomes, n=56 genomes and n=8,757 single cells). Genomic alterations (including copy number alterations and somatic mutations), clonal architectures and transcriptome dynamics during adenocarcinoma carcinogenesis were comprehensively investigated. RESULTS: Genomic evolutionary analysis showed that adjacent lesions from the same patient with FAP can originate from the same cancer-primed cell. In addition, the tricarboxylic acid cycle pathway was strongly repressed in adenomas and was then slightly alleviated in carcinomas. Cells from the 'normal' colon epithelium of patients with FAP already showed metabolic reprogramming compared with cells from the normal colon epithelium of patients with sporadic colorectal cancer. CONCLUSIONS: The process described in the previously reported field cancerisation model also occurs in patients with FAP and can contribute to the formation of adjacent lesions in patients with FAP. Reprogramming of carbohydrate metabolism has already occurred at the precancerous adenoma stage. Our study provides an accurate picture of the genomic and transcriptomic landscapes during the initiation and progression of carcinogenesis, especially during the transition from adenoma to carcinoma.


Assuntos
Polipose Adenomatosa do Colo/genética , Carcinogênese/genética , Polipose Adenomatosa do Colo/metabolismo , Carcinogênese/metabolismo , Feminino , Perfilação da Expressão Gênica , Humanos , Masculino , Redes e Vias Metabólicas/genética , Linhagem , Lesões Pré-Cancerosas/genética , Lesões Pré-Cancerosas/metabolismo , Análise de Sequência de RNA , Análise de Célula Única , Sequenciamento do Exoma , Sequenciamento Completo do Genoma
15.
EMBO J ; 35(18): 2045-59, 2016 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-27481934

RESUMO

8-oxo-7,8-dihydroxy-2'-deoxyguanosine (8-oxo-dG) has high mutagenic potential as it is prone to mispair with deoxyadenine (dA). In order to maintain genomic integrity, post-replicative 8-oxo-dG:dA mispairs are removed through DNA polymerase lambda (Pol λ)-dependent MUTYH-initiated base excision repair (BER). Here, we describe seven novel crystal structures and kinetic data that fully characterize 8-oxo-dG bypass by Pol λ. We demonstrate that Pol λ has a flexible active site that can tolerate 8-oxo-dG in either the anti- or syn-conformation. Importantly, we show that discrimination against the pro-mutagenic syn-conformation occurs at the extension step and identify the residue responsible for this selectivity. This residue acts as a kinetic switch, shunting repair toward long-patch BER upon correct dCMP incorporation, thus enhancing repair efficiency. Moreover, this switch also provides a potential mechanism to increase repair fidelity of MUTYH-initiated BER.


Assuntos
Pareamento Incorreto de Bases , DNA Polimerase beta/química , DNA Polimerase beta/metabolismo , Reparo do DNA , Desoxiguanosina/análogos & derivados , 8-Hidroxi-2'-Desoxiguanosina , Domínio Catalítico , Cristalografia por Raios X , Desoxiguanosina/metabolismo , Humanos , Cinética , Conformação Proteica
16.
Invest New Drugs ; 38(3): 894-898, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-31377904

RESUMO

Colorectal carcinomas (CRCs) caused by hereditary biallelic MUTYH gene mutations are characterized by elevated mutation load and high lymphocyte infiltration. Given that these tumor features are associated with the response to immune checkpoint inhibitors, we administered nivolumab to a CRC patient who carried two inactive MUTYH alleles (p.Y179C and p.G396D) and previously experienced failure of chemotherapy. This experimental treatment resulted in a pronounced tumor response. We further compared tumor lymphocyte infiltration in MUTYH-associated (n = 3), high-level microsatellite instability (MSI-H, n = 8) and microsatellite stable (MSS, n = 6) CRCs. Both MUTYH-driven and MSI-H CRCs showed noticeably higher lymphocyte densities than those of microsatellite stable tumors; this difference reached the level of statistical significance for the comparison of central areas of the tumors (p = 0.02 and 0.03, respectively) but not for the invasive tumor margins. Although MUTYH-associated tumors are exceptionally rare among unselected CRC cases, their share in CRC patients with somatic KRAS p.G12C substitution approaches 5-25%. These observations provide a rationale for further evaluation of the efficacy of the immune checkpoint blockade in MUTYH-driven CRC.


Assuntos
Neoplasias Colorretais/tratamento farmacológico , DNA Glicosilases/metabolismo , Inibidores de Checkpoint Imunológico/uso terapêutico , Idoso , Alelos , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , DNA Glicosilases/genética , Feminino , Humanos , Linfócitos do Interstício Tumoral/efeitos dos fármacos , Linfócitos do Interstício Tumoral/metabolismo , Instabilidade de Microssatélites/efeitos dos fármacos , Mutação/efeitos dos fármacos , Mutação/genética
17.
Colorectal Dis ; 22(10): 1271-1278, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32307808

RESUMO

AIM: The aim was to determine the presentation, management and outcomes of MUTYH-associated polyposis (MAP). METHOD: A prospectively maintained database was used to identify patients with MAP. Demographic data and data on germline mutation, surgical management, histopathology of tumours and endoscopic surveillance were collected. RESULTS: In all, 134 patients with MAP were identified. The majority presented symptomatically (n = 83). Sixty-eight patients developed cancer (seven synchronous, 12 metachronous). The median age at diagnosis of first colorectal cancer was 47 years (range 33-74 years). Cancers occurred in the context of a few adenomas (< 10). The majority of patients (n = 108) had surgery as the first line management. One patient received palliative care. Twenty-five patients had endoscopic surveillance as first line management; no cancers occurred in this group. Patients who had segmental resection and postoperative surveillance still appeared to be at risk of metachronous cancer (5/30, 17%). CONCLUSIONS: MUTYH testing should be considered even in the context of cancers occurring with fewer than 10 adenomas. In cases of primary colorectal cancers, extended surgery should be considered if patients do not have access to high quality endoscopic surveillance postoperatively. For some patients, endoscopic therapy is an appropriate and safe option in expert hands.


Assuntos
Adenoma , Polipose Adenomatosa do Colo , Neoplasias Colorretais , DNA Glicosilases , Adenoma/genética , Adenoma/terapia , Polipose Adenomatosa do Colo/genética , Polipose Adenomatosa do Colo/cirurgia , Adulto , Idoso , Neoplasias Colorretais/genética , Neoplasias Colorretais/terapia , DNA Glicosilases/genética , Predisposição Genética para Doença , Humanos , Pessoa de Meia-Idade , Mutação , Fenótipo
18.
Hum Mutat ; 40(4): 472-482, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30653782

RESUMO

The human DNA repair gene MUTYH, whose mutational loss causes a colorectal polyposis and cancer predisposition, contains three alternative first exons. In order to analyze alternative transcription and the effect of genetic alterations found in humans, we established a cell-based minigene experimental model supporting transcription and splicing and thoroughly verified its functionality. We identified highly conserved promoter areas and inactivated them in the minigene, and also introduced six human variants. Moreover, the potential contribution of CpG island methylation and specific transcription factors on MUTYH transcription was addressed. The findings allowed to attribute regulatory roles to three conserved motifs in the promoter: an M4 motif, a transcription factor IIB recognition element, and a GC box. Moreover, the data showed that three patient variants compromised MUTYH expression and therefore have the potential to cause pathogenic effects. We did not find evidence for a biologically relevant contribution of CpG island methylation or a direct transcriptional activation by DNA damage. Besides insight into the regulation of MUTYH transcription, the work therefore provides a functional MUTYH minigene experimental system suitable as a diagnostic tool for analyzing patient variants, and a functional map of the promotor that also can facilitate pathogenicity classifications of human variants.


Assuntos
Processamento Alternativo , DNA Glicosilases/genética , Regulação da Expressão Gênica , Variação Genética , Regiões Promotoras Genéticas , Linhagem Celular , Biologia Computacional/métodos , Ilhas de CpG , Metilação de DNA , Análise Mutacional de DNA , Éxons , Perfilação da Expressão Gênica , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Leucócitos Mononucleares , Mutação , Estresse Oxidativo
20.
BMC Cancer ; 19(1): 324, 2019 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-30953464

RESUMO

BACKGROUND: We are reporting a rare case of MUTYH-associated polyposis, a colorectal cancer hereditary syndrome, diagnosticated after an intussusception. Colorectal cancer is an important cause of cancer related mortality that can be manifested by an intussusception, a rare occurrence in adults and almost always related to tumors. Approximately 5% of colorectal cancers can be attributed to syndromes known to cause hereditary colorectal cancer, such as MUTYH-associated polyposis, autosomal genetic syndrome associated with this disease. CASE PRESENTATION: We present the case of a 44 years old male, that sought medical consultation with a complaint of abdominal discomfort, that after five days changed its characteristics. The patient was sent to the emergency department were a CT-scan revealed intestinal sub-occlusion by ileocolic invagination. Right colectomy was carried out. The anatomic-pathological examination revealed a moderately differentiated mucinous adenocarcinoma and multiples sessile polyps, which led to the suspicion of a genetic syndrome. In the genetics analysis two mutations were observed in the MUTYH gene, and MUTYH-associated polyposis was diagnosticated. CONCLUSION: This case demonstrates the importance of meticulous analysis of the patient examinations results to identify possible discrete alterations that can lead to improved understanding of disease.


Assuntos
Adenocarcinoma Mucinoso/diagnóstico , Polipose Adenomatosa do Colo/diagnóstico , DNA Glicosilases/genética , Doenças do Íleo/etiologia , Intussuscepção/etiologia , Adenocarcinoma Mucinoso/complicações , Adenocarcinoma Mucinoso/genética , Adenocarcinoma Mucinoso/cirurgia , Polipose Adenomatosa do Colo/complicações , Polipose Adenomatosa do Colo/genética , Polipose Adenomatosa do Colo/cirurgia , Adulto , Colectomia , Colo/diagnóstico por imagem , Colo/patologia , Colo/cirurgia , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Humanos , Doenças do Íleo/diagnóstico por imagem , Doenças do Íleo/cirurgia , Intussuscepção/diagnóstico por imagem , Intussuscepção/cirurgia , Masculino , Tomografia Computadorizada por Raios X
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