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1.
Cell Biochem Funct ; 37(8): 572-577, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31502267

RESUMO

Among the types of cancers that may occur in the oral cavity, squamous cell carcinomas (SCC) of the mouth have a higher incidence and are associated with increased rates of morbidity and mortality. Among steps from the beginning to the progression of the tumour, DNA Repair System is highlighted. The present study aims to conduct a systematic review of the literature on the expression of the repair genes hMSH2 and hMSH6 in patients with SCC in the mouth and oropharyngeal region. The search was performed in databases such as PubMed, Lilacs, and Scielo and included articles published in English from 1999 until 2015. The search in the above-mentioned databases initially yielded 15 scientific articles related to the proposed objective. After a detailed analysis of each of them, only 8 were included in the present review, precisely because they met the inclusion criteria determined in the method. All the reviewed works were unanimous in recognizing the veracity and complexity of the Genomic Repair System, also called Mismatch Repair System, confirming the participation of repair gene proteins (such as hMSH2 and hMSH6) in patients with oral cancer and even of lesions that are susceptible to malignization. SIGNIFICANCE OF THE STUDY: Worldwide, there are an estimated 300 thousand new cases of oral cancer per year. Studies have shown a greater risk in individuals who are smokers and alcohol consumers in developing mouth cancer. Many steps are observed from the beginning to the progression of the tumour, highlighted among them is the moment in which genetic, and epigenetic alterations will interfere in the functioning of the DNA Repair System. This work presents a survey of current knowledge about the involvement of repair genes, especially those of the MutSα system, in the development and progression of oral cancer.


Assuntos
Carcinoma de Células Escamosas/patologia , Reparo do DNA/genética , Neoplasias Bucais/patologia , Carcinoma de Células Escamosas/genética , Proteínas de Ligação a DNA/genética , Bases de Dados Factuais , Humanos , Neoplasias Bucais/genética , Proteína 2 Homóloga a MutS/genética
2.
World Neurosurg ; 132: 219-222, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31491579

RESUMO

BACKGROUND: Lynch syndrome (LS) is a cancer-predisposing condition resulting from germline mutations in deoxyribonucleic acid mismatch repair genes. Patients are at high risk for a multitude of tumors, but no reports of undifferentiated sellar carcinomas have previously been described. CASE DESCRIPTION: A 56-year-old female with LS due to MSH2 and MSH6 mutations presented with panhypopituitarism and a sellar mass. She was initially diagnosed with pituitary apoplexy and treated nonoperatively. The mass self-resolved. The mass recurred 2 years later, and she underwent endoscopic endonasal biopsy demonstrating an undifferentiated carcinoma of the sella with MSH2 and MSH6 loss. The tumor was negative for pituitary markers and weakly positive for p63. The patient further developed lung and bone metastases and was treated with radiation and chemotherapy. CONCLUSIONS: This is the first report of an undifferentiated carcinoma of the sella. Our patient harbored a diagnosis of LS and demonstrated local tumor recurrence and aggressive systemic progression. Patients with LS should undergo close follow-up and active surveillance to detect and treat these aggressive lesions in a timely manner.


Assuntos
Carcinoma/complicações , Neoplasias Colorretais Hereditárias sem Polipose/complicações , Neoplasias Hipofisárias/complicações , Neoplasias Ósseas/secundário , Carcinoma/patologia , Carcinoma/cirurgia , Neoplasias Colorretais Hereditárias sem Polipose/genética , Neoplasias Colorretais Hereditárias sem Polipose/patologia , Terapia Combinada , Proteínas de Ligação a DNA/genética , Feminino , Humanos , Biópsia Guiada por Imagem , Neoplasias Pulmonares/secundário , Pessoa de Meia-Idade , Proteína 2 Homóloga a MutS/genética , Recidiva Local de Neoplasia , Procedimentos Neurocirúrgicos/métodos , Neoplasias Hipofisárias/patologia , Neoplasias Hipofisárias/cirurgia , Tomografia Computadorizada por Raios X
3.
Genet Test Mol Biomarkers ; 23(8): 573-579, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31373852

RESUMO

Aim: Although hMLH1 and hMSH2 are closely associated with the development and drug resistance of multiple types of tumors, their role in renal tumors remains unclear. This study was designed to examine the relationship between renal tumor development and polymorphisms in the hMLH1 and hMSH2 genes. Methods: The study included 180 patients with renal tumors that were confirmed by pathological examination and 199 healthy controls. The clinical and pathological stages of the tumor samples were determined, and DNA was extracted from the peripheral blood of the subjects. Polymorphisms in the hMLH1 and hMSH2 loci were identified using the 1000 genomes database and the multiplex ligase detection method. Correlation analyses was performed using single nucleotide polymorphism tests. Results: 88.9% (160/180) of the tumor specimens were identified as clear cell renal cell carcinoma (CCRC) and 89.4% (161/180) were stage I carcinomas. Three hMLH1 and nine hMSH2 polymorphic sites were identified, and the frequency of the AA genotype of the hMSH2 rs2303424 variant was found to be significantly higher in the renal tumor group (odds ratio [OR] = 1.37, 95% confidence interval [CI]: 1.02-1.86) in the additive model (p = 0.029), the recessive model (p = 0.005), and codominant model (p = 0.02). Multiple testing corrections were performed and the differences between the clear cell carcinoma and control samples remained significant. Compared with the controls, the distribution of the GG genotype of the hMSH2 rs11886591 locus was significantly higher in the clear cell carcinoma group (OR = 0.80, 95% CI: 0.59-1.10, p = 0.04) after multiple testing corrections in the dominant model. Conclusion: The AA genotype at the rs2303424 locus and GG genotype at rs11886591 locus of the DNA repair gene hMSH2 were closely associated with the development of renal tumors. Further studies are needed on larger cohorts to confirm this correlation.


Assuntos
Neoplasias Renais/genética , Proteína 1 Homóloga a MutL/genética , Proteína 2 Homóloga a MutS/genética , China , Reparo de Erro de Pareamento de DNA , Feminino , Estudos de Associação Genética , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Estudos Retrospectivos
4.
J Environ Radioact ; 208-209: 106012, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31323602

RESUMO

Previous studies evidenced the critical role of the mismatch repair system in DNA damage recognition, cell cycle arrest, apoptosis and DNA repair. MLH1 and MSH2 genes belong to repairing complexes of mismatch repair system. The side effects of ionizing radiation on the human health were proved, but researches on the inhabitants of high background radiation areas, with extra-ordinary radiation exposure, showed that the prevalence of cancer or radiation-related diseases is not significantly higher than normal background areas. The city of Ramsar, in northern Iran, has the highest level of natural background radiation in the world and in this study, we aimed to evaluate the expression of MLH1 and MSH2 genes among the inhabitants of high background radiation areas of Ramsar compared to normal background radiation areas. In the present study, 60 blood sample from high and normal background inhabitants were collected and we MLH1, and MSH2 genes expressions in residents of high background radiation area compared with normal background radiation area were evaluated by Quantitative Real-Time PCR. Our results showed a significant upregulation of MLH1 in residents of high background radiation area. Also, there is a significant association between MLH1 and MSH2 gene expression in both sexes. Also, the increased expression of MLH1 in HBRA is notable. There is an increased expression of MLH1 in age above 50 and a decreased expression of MSH2 in ages under 50 years (P < 0.0001). These findings are suggesting the triggering of Mismatch Repair system in response to high-level of natural background radiation.


Assuntos
Radiação de Fundo , Proteína 1 Homóloga a MutL/genética , Proteína 2 Homóloga a MutS/genética , Exposição à Radiação/análise , Reparo de Erro de Pareamento de DNA , Reparo do DNA , Feminino , Humanos , Irã (Geográfico) , Masculino , Pessoa de Meia-Idade
5.
Int J Clin Oncol ; 24(9): 999-1011, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31273487

RESUMO

Lynch syndrome is a cancer-predisposing syndrome inherited in an autosomal-dominant manner, wherein colon cancer and endometrial cancer develop frequently in the family, it results from a loss-of-function mutation in one of four different genes (MLH1, MSH2, MSH6, and PMS2) encoding mismatch repair proteins. Being located immediately upstream of the MSH2 gene, EPCAM abnormalities can affect MSH2 and cause Lynch syndrome. Mismatch repair proteins are involved in repairing of incorrect pairing (point mutations and deletion/insertion of simple repetitive sequences, so-called microsatellites) that can arise during DNA replication. MSH2 forms heterodimers with MSH6 or MSH3 (MutSα, MutSß, respectively) and is involved in mismatch-pair recognition and initiation of repair. MLH1 forms a complex with PMS2, and functions as an endonuclease. If the mismatch repair system is thoroughly working, genome integrity is maintained completely. Lynch syndrome is a state of mismatch repair deficiency due to a monoallelic abnormality of any mismatch repair genes. The phenotype indicating the mismatch repair deficiency can be frequently shown as a microsatellite instability in tumors. Children with germline biallelic mismatch repair gene abnormalities were reported to develop conditions such as gastrointestinal polyposis, colorectal cancer, brain cancer, leukemia, etc., and so on, demonstrating the need to respond with new concepts in genetic counseling. In promoting cancer genome medicine in a new era, such as by utilizing immune checkpoints, it is important to understand the genetic and genomic molecular background, including the status of mismatch repair deficiency.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/genética , Reparo de Erro de Pareamento de DNA/fisiologia , Neoplasias Encefálicas/genética , Criança , Reparo de Erro de Pareamento de DNA/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Neoplasias do Endométrio/genética , Molécula de Adesão da Célula Epitelial/genética , Feminino , Aconselhamento Genético , Testes Genéticos , Humanos , Instabilidade de Microssatélites , Endonuclease PMS2 de Reparo de Erro de Pareamento/genética , Endonuclease PMS2 de Reparo de Erro de Pareamento/metabolismo , Proteína 1 Homóloga a MutL/genética , Proteína 1 Homóloga a MutL/metabolismo , Proteína 2 Homóloga a MutS/genética , Proteína 2 Homóloga a MutS/metabolismo , Mutação
6.
Science ; 364(6439): 485-491, 2019 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-31048490

RESUMO

Tumors with mismatch repair deficiency (MMR-d) are characterized by sequence alterations in microsatellites and can accumulate thousands of mutations. This high mutational burden renders tumors immunogenic and sensitive to programmed cell death-1 (PD-1) immune checkpoint inhibitors. Yet, despite their tumor immunogenicity, patients with MMR-deficient tumors experience highly variable responses, and roughly half are refractory to treatment. We present experimental and clinical evidence showing that the degree of microsatellite instability (MSI) and resultant mutational load, in part, underlies the variable response to PD-1 blockade immunotherapy in MMR-d human and mouse tumors. The extent of response is particularly associated with the accumulation of insertion-deletion (indel) mutational load. This study provides a rationale for the genome-wide characterization of MSI intensity and mutational load to better profile responses to anti-PD-1 immunotherapy across MMR-deficient human cancers.


Assuntos
Reparo de Erro de Pareamento de DNA/genética , Imunoterapia/métodos , Instabilidade de Microssatélites , Neoplasias/genética , Neoplasias/terapia , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Animais , Anticorpos/uso terapêutico , Variação Genética , Melanoma Experimental/genética , Melanoma Experimental/terapia , Camundongos , Proteína 2 Homóloga a MutS/genética , Mutação , Resultado do Tratamento
7.
Fam Cancer ; 18(3): 349-352, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31111311

RESUMO

Subtotal colectomy is usually the therapy of choice in Lynch syndrome patients diagnosed with colon cancer. In patients who develop cancer after the age of 50-60 years, segmental colectomy is considered a good alternative. Although the endoscopic treatment of early colorectal cancer in non-Lynch patients has increased in the last decades, almost all patients with a Lynch syndrome-associated colorectal malignancy undergo surgery, even if the tumour is diagnosed in a (very) early stage. One of the endoscopic treatment options for early colorectal cancer is an endoscopic full thickness resection (eFTR). This treatment modality allows optimal pathological examination of the resection specimen, as a transmural resection is performed with optimal T-staging of the tumour. We report a case of a 62 year old man, diagnosed with MSH2-Lynch syndrome, who underwent successful eFTR treatment of an early (pT1) colon cancer located in the ascending colon, with no signs of recurrence 12 months after treatment. We discuss the pros and cons of endoscopic resection of early colorectal carcinoma in Lynch syndrome patients.


Assuntos
Neoplasias do Colo/cirurgia , Colonoscopia/métodos , Neoplasias Colorretais Hereditárias sem Polipose/cirurgia , Adenocarcinoma/genética , Adenocarcinoma/cirurgia , Carcinoma/genética , Carcinoma/cirurgia , Colo Ascendente/cirurgia , Neoplasias do Colo/patologia , Colonoscopia/instrumentação , Neoplasias Colorretais Hereditárias sem Polipose/patologia , Detecção Precoce de Câncer , Humanos , Neoplasias Renais/genética , Neoplasias Renais/cirurgia , Masculino , Pessoa de Meia-Idade , Proteína 2 Homóloga a MutS/genética , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/cirurgia
8.
Genetics ; 212(3): 655-665, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31126976

RESUMO

Microsatellite sequences have an enhanced susceptibility to mutation, and can act as sentinels indicating elevated mutation rates and increased risk of cancer. The probability of mutant fixation within the intestinal epithelium is dictated by a combination of stem cell dynamics and mutation rate. Here, we exploit this relationship to infer microsatellite mutation rates. First a sensitive, multiplexed, and quantitative method for detecting somatic changes in microsatellite length was developed that allowed the parallel detection of mutant [CA]n sequences from hundreds of low-input tissue samples at up to 14 loci. The method was applied to colonic crypts in Mus musculus, and enabled detection of mutant subclones down to 20% of the cellularity of the crypt (∼50 of 250 cells). By quantifying age-related increases in clone frequencies for multiple loci, microsatellite mutation rates in wild-type and Msh2-deficient epithelium were established. An average 388-fold increase in mutation per mitosis rate was observed in Msh2-deficient epithelium (2.4 × 10-2) compared to wild-type epithelium (6.2 × 10-5).


Assuntos
Células-Tronco Adultas/metabolismo , Mucosa Intestinal/citologia , Repetições de Microssatélites , Proteína 2 Homóloga a MutS/genética , Taxa de Mutação , Células-Tronco Adultas/citologia , Animais , Feminino , Mucosa Intestinal/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitose , Proteína 2 Homóloga a MutS/deficiência
9.
Fam Cancer ; 18(3): 343-348, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31114938

RESUMO

A high colorectal cancer (CRC) incidence is observed in Tunisia, with a relatively high proportion of patients developing CRC before the age of 40. While this suggests a genetic susceptibility, only a few Tunisian Lynch Syndrome families have been described. In this study we aimed to identify the underlying genetic cause in 32 patients with early onset CRC and/or a positive family history. Of twenty-four patients' tumor or biopsies could be analyzed with immunohistochemical staining to detect loss of expression of one of the MMR proteins. Ten tumors showed loss of expression, of which one tumor was from a patient where a germline pathogenic MSH2 variant was detected previously with Sanger sequencing. Next generation sequencing of the MMR, POLE and POLD1 genes was performed in leukocyte and tumor DNA of the remaining nine patients, as well as in two patients with MMR-proficient tumors, but with severe family history. In six of 11 patients a germline variant was detected in MLH1 (n = 5) or MSH2 (n = 1). Two of six patients were from the same family and both were found to carry a novel in-frame MLH1 deletion, predicted to affect MLH1 function. All MLH1 variant carriers had loss of heterozygosity with retention of the variant in the tumors, while a somatic pathogenic variant was detected in the patient with the germline MSH2 variant.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/genética , Mutação em Linhagem Germinativa , Sequenciamento de Nucleotídeos em Larga Escala , Adulto , Idoso , Neoplasias Colorretais/genética , DNA Polimerase II/genética , DNA Polimerase III/genética , Saúde da Família , Feminino , Deleção de Genes , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Proteína 1 Homóloga a MutL/genética , Proteína 2 Homóloga a MutS/genética , Linhagem , Proteínas de Ligação a Poli-ADP-Ribose/genética , Tunísia , Adulto Jovem
10.
Fam Cancer ; 18(3): 331-342, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30989425

RESUMO

Many colorectal cancers (CRCs) that exhibit microsatellite instability (MSI) are not explained by MLH1 promoter methylation or germline mutations in mismatch repair (MMR) genes, which cause Lynch syndrome (LS). Instead, these Lynch-like syndrome (LLS) patients have somatic mutations in MMR genes. However, many of these patients are young and have relatives with cancer, suggesting a hereditary entity. We performed germline sequence analysis in LLS patients and determined their tumor's mutational profiles using FFPE DNA. Six hundred and fifty-four consecutive CRC patients were screened for suspected LS using MSI and absence of MLH1 methylation. Suspected LS cases were exome sequenced to identify germline and somatic mutations. Single nucleotide variants were used to characterize mutational signatures. We identified 23 suspected LS cases. Germline sequence analysis of 16 available samples identified five cases with LS mutations and 11 cases without LS mutations, LLS. Most LLS tumors had a combination of somatic MMR gene mutation and loss of heterozygosity. LLS patients were relatively young and had excess first-degree relatives with cancer. Four of the 11 LLS patients had rare likely pathogenic variants in genes that maintain genome integrity. Moreover, tumors from this group had a distinct mutational signature compared to tumors from LLS patients lacking germline mutations in these genes. In summary, more than a third of the LLS patients studied had germline mutations in genes that maintain genome integrity and their tumors had a distinct mutational signature. The possibility of hereditary factors in LLS warrants further studies so counseling can be properly informed.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/genética , Reparo de Erro de Pareamento de DNA , Mutação em Linhagem Germinativa , Adulto , Idoso , Idoso de 80 Anos ou mais , Metilação de DNA , Proteínas de Ligação a DNA/genética , Feminino , Heterozigoto , Humanos , Masculino , Instabilidade de Microssatélites , Pessoa de Meia-Idade , Endonuclease PMS2 de Reparo de Erro de Pareamento/genética , Proteína 1 Homóloga a MutL/genética , Proteína 2 Homóloga a MutS/genética , Análise de Sequência de DNA
11.
Gastroenterology ; 157(2): 421-431, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30998989

RESUMO

BACKGROUND & AIMS: Approximately 75% of patients with suspected Lynch syndrome carry variants in MLH1 or MSH2, proteins encoded by these genes are required for DNA mismatch repair (MMR). However, 30% of these are variants of unknown significance (VUS). A assay that measures cell response to the cytotoxic effects of a methylating agent can determine the effects of VUS in MMR genes and identify patients with constitutional MMR-deficiency syndrome. We adapted this method to test the effects of VUS in MLH1 and MSH2 genes found in patients with suspected Lynch syndrome. METHODS: We transiently expressed MLH1 or MSH2 variants in MLH1- or MSH2-null human colorectal cancer cell lines (HCT116 or LoVo), respectively. The MMR process causes death of cells with methylation-damaged DNA bases, so we measured proportions of cells that undergo death following exposure to the methylating agent; cells that escaped its toxicity were considered to have variants that affect function of the gene product. Using this assay, we analyzed 88 variants (mainly missense variants), comprising a validation set of 40 previously classified variants (19 in MLH1 and 21 in MSH2) and a prospective set of 48 VUS (25 in MLH1 and 23 in MSH2). Prediction scores were calculated for all VUS according to the recommendations of the American College of Medical Genetics and Genomics, based on clinical, somatic, in silico, population, and functional data. RESULTS: The assay correctly classified 39 of 40 variants in the validation set. The assay identified 12 VUS that did alter function of the gene product and 28 VUS that did not; the remaining 8 VUS had intermediate effects on MMR capacity and could not be classified. Comparison of assay results with prediction scores confirmed the ability of the assay to discriminate VUS that affected the function of the gene products from those that did not. CONCLUSIONS: Using an assay that measures the ability of the cells to undergo death following DNA damage induction by a methylating agent, we were able to assess whether variants in MLH1 and MSH2 cause defects in DNA MMR. This assay might be used to help assessing the pathogenicity of VUS in MLH1 and MSH2 found in patients with suspected Lynch syndrome.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Metilação de DNA/genética , Testes Genéticos/métodos , Proteína 1 Homóloga a MutL/genética , Proteína 2 Homóloga a MutS/genética , Bioensaio/métodos , Linhagem Celular Tumoral , Neoplasias Colorretais Hereditárias sem Polipose/genética , Simulação por Computador , Metilação de DNA/efeitos dos fármacos , Reparo de Erro de Pareamento de DNA/genética , Estudos de Viabilidade , Mutação em Linhagem Germinativa , Guanina/análogos & derivados , Guanina/farmacologia , Humanos , Metilnitronitrosoguanidina/toxicidade
12.
Tumour Biol ; 42(4): 1010428319843042, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30973070

RESUMO

Inflammation is an important etiological factor of colorectal carcinoma and may be related to colorectal carcinoma growth and proliferation. This study aimed to verify whether the presence of chronic inflammation represented by tumor necrosis factor-α, interleukin-2, interleukin-6, and interleukin-10 gene expression is related to hMLH1, hMSH2, hMSH6, and PMS2 gene expression and the corresponding protein levels of these genes from the DNA repair system. A total of 83 patients were operated on for curative or palliative colorectal carcinoma. Expression of the inflammatory response genes tumor necrosis factor-α, interleukin-2, interleukin-6, and interleukin-10 as well as expression of the hMLH1, hMSH2, hMSH6, and PMS2 genes of the DNA repair system (mismatch repair) and the expression levels of the corresponding mismatch repair proteins were measured in neoplastic tissue by reverse transcription polymerase chain reaction and immunohistochemistry, respectively. Associations were observed between hMSH6 mRNA expression and interleukin-2 mRNA expression (p = 0.026) as well as between hMLH1 and hMSH2 gene expression and tumor necrosis factor-α gene expression (p = 0.042). Higher tissue levels of interleukin-2 and tumor necrosis factor-α gene expression were associated with lower hMSH6, hMLH1, and hMSH2 gene expression.


Assuntos
Carcinogênese/genética , Proliferação de Células/genética , Neoplasias Colorretais/genética , Inflamação/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/patologia , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Progressão da Doença , Feminino , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Inflamação/patologia , Interleucina-10/genética , Interleucina-2/genética , Interleucina-6/genética , Masculino , Pessoa de Meia-Idade , Endonuclease PMS2 de Reparo de Erro de Pareamento/genética , Proteína 1 Homóloga a MutL/genética , Proteína 2 Homóloga a MutS/genética , Fator de Necrose Tumoral alfa/genética
13.
Genes Chromosomes Cancer ; 58(9): 657-664, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-30968502

RESUMO

The mutational spectrum of the MMR genes is highly heterogeneous, but specific mutations are observed at high frequencies in well-defined populations or ethnic groups, due to founder effects. The MSH2 mutation c.2152C>T, p.(Gln718*), has occasionally been described in Lynch families worldwide, including in Portuguese Lynch syndrome families. During genetic testing for Lynch syndrome at the Portuguese Oncology Institutes of Porto and Lisbon, this mutation was identified in 28 seemingly unrelated families. In order to evaluate if this alteration is a founder mutation, haplotype analysis using microsatellite and SNP markers flanking the MSH2 gene was performed in the 28 probands and 87 family members. Additionally, the geographic origin of these families was evaluated and the age of the mutation estimated. Twelve different haplotypes were phased for 13 out of the 28 families and shared a conserved region of ∼3.6 Mb. Based on the mutation and recombination events observed in the microsatellite haplotypes and assuming a generation time of 25 years, the age estimate for the MSH2 mutation was 273 ± 64 years. The geographic origins of these families were mostly from the Northern region of Portugal. Concluding, these results suggest that the MSH2 c.2152C>T alteration is a founder mutation in Portugal with a relatively recent origin. Furthermore, its high proportion indicates that screening for this mutation as a first step, together with the previously reported Portuguese founder mutations, may be cost-effective in genetic testing of Lynch syndrome suspects of Portuguese ancestry.


Assuntos
Códon sem Sentido , Neoplasias Colorretais Hereditárias sem Polipose/genética , Efeito Fundador , Proteína 2 Homóloga a MutS/genética , Feminino , Haplótipos , Humanos , Masculino , Repetições de Microssatélites , Polimorfismo de Nucleotídeo Único , Portugal
14.
Mol Genet Genomic Med ; 7(5): e587, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30916491

RESUMO

BACKGROUND: Inherited epimutations of Mismatch Repair (MMR) genes are responsible for Lynch Syndrome (LS) in a small, but well defined, subset of patients. Methylation of the MSH2 promoter consequent to the deletion of the upstream EPCAM gene is found in about 1%-3% of the LS patients and represents a classical secondary, constitutional and tissue-specific epimutation. Several different EPCAM deletions have been reported worldwide, for the most part representing private variants caused by an Alu-mediated recombination. METHODS: 712 patients with suspected LS were tested for MMR mutation in our Institute. EPCAM deletions were detected by multiplex ligation-dependent probe amplification (MLPA) and then defined by Long-Range polymerase chain reaction (PCR)/Sanger sequencing. A comprehensive molecular characterization of colorectal cancer (CRC) tissues was carried out by immunohistochemistry of MMR proteins, Microsatellite Instability (MSI) assay, methylation specific MLPA and transcript analyses. In addition, somatic deletions and/or variants were investigated by MLPA and next generation sequencing (NGS). RESULTS: An EPCAM deletion was found in five unrelated probands in Italy: variants c.556-490_*8438del and c.858+1193_*5826del are novel; c.859-1430_*2033del and c.859-670_*530del were previously reported. All probands were affected by CRC at young age; tumors showed MSI and abnormal MSH2/MSH6 proteins expression. MSH2 promoter methylation, as well as aberrant in-frame or out-of-frame EPCAM/MSH2 fusion transcripts, were detected in CRCs and normal mucosae. CONCLUSION: An EPCAM deletion was the causative variant in about 2% of our institutional series of 224 LS patients, consistent with previously estimated frequencies. Early age and multiple CRCs was the main clinical feature of this subset of patients.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/genética , Molécula de Adesão da Célula Epitelial/genética , Deleção de Genes , Frequência do Gene , Adulto , Metilação de DNA , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Proteína 2 Homóloga a MutS/genética , Proteína 2 Homóloga a MutS/metabolismo , Fenótipo
15.
EMBO J ; 38(9)2019 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-30886049

RESUMO

Mutations in Lef1 occur in human and mouse sebaceous gland (SG) tumors, but their contribution to carcinogenesis remains unclear. Since Gata6 controls lineage identity in SG, we investigated the link between these two transcription factors. Here, we show that Gata6 is a ß-catenin-independent transcriptional target of mutant Lef1. During epidermal development, Gata6 is expressed in a subset of Sox9-positive Lef1-negative hair follicle progenitors that give rise to the upper SG Overexpression of Gata6 by in utero lentiviral injection is sufficient to induce ectopic sebaceous gland elements. In mice overexpressing mutant Lef1, Gata6 ablation increases the total number of skin tumors yet decreases the proportion of SG tumors. The increased tumor burden correlates with impaired DNA mismatch repair and decreased expression of Mlh1 and Msh2 genes, defects frequently observed in human sebaceous neoplasia. Gata6 specifically marks human SG tumors and also defines tumors with elements of sebaceous differentiation, including a subset of basal cell carcinomas. Our findings reveal that Gata6 controls sebaceous gland development and cancer.


Assuntos
Fator de Transcrição GATA6/metabolismo , Fator 1 de Ligação ao Facilitador Linfoide/metabolismo , Fator 1 de Ligação ao Facilitador Linfoide/fisiologia , Neoplasias das Glândulas Sebáceas/patologia , Neoplasias Cutâneas/patologia , Células-Tronco/patologia , Animais , Proliferação de Células , Dano ao DNA , Feminino , Folículo Piloso/metabolismo , Folículo Piloso/patologia , Humanos , Fator 1 de Ligação ao Facilitador Linfoide/genética , Masculino , Camundongos , Camundongos Knockout , Proteína 1 Homóloga a MutL/genética , Proteína 1 Homóloga a MutL/metabolismo , Proteína 2 Homóloga a MutS/genética , Proteína 2 Homóloga a MutS/metabolismo , Mutação , Neoplasias das Glândulas Sebáceas/genética , Neoplasias das Glândulas Sebáceas/metabolismo , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/metabolismo , Células-Tronco/metabolismo , beta Catenina/genética , beta Catenina/metabolismo
16.
Jpn J Clin Oncol ; 49(5): 477-480, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30882153

RESUMO

The proband was a 62-year-old man with ureter cancer. He had a history of metachronous colorectal and gastric cancer. Immunohistochemical staining showed the absence of both MSH2 and MSH6 proteins in the ureter cancer and other available cancer tissue specimens. Genetic testing was conducted to identify the causative genes of hereditary gastrointestinal cancer syndromes including mismatch repair genes. We detected a germline variant, c.2635-3delC, within the splice acceptor site of exon 16, in the MSH2 gene. To investigate whether this variant affected splicing of the gene, RNA sequencing was performed using blood samples. We observed a substantial amount of the transcripts that lacked proper splicing of intron 15 in the indexed case, whereas, a very low amount of such aberrant transcripts was detected in the controls, strongly indicating an association between the variant and splicing defect. These results indicate that MSH2 c.2635-3delC affects normal splicing and might be a cause of Lynch syndrome.


Assuntos
Pareamento de Bases/genética , Neoplasias Colorretais Hereditárias sem Polipose/genética , Predisposição Genética para Doença , Íntrons/genética , Proteína 2 Homóloga a MutS/genética , Processamento de RNA/genética , Deleção de Sequência , Adulto , Sequência de Bases , Simulação por Computador , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
18.
Fam Cancer ; 18(3): 317-325, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30729418

RESUMO

A subset of colorectal cancer (CRC) cases are attributable to Lynch syndrome (LS), a hereditary form of CRC. Effective evaluation for LS can be done on CRC tumors to guide diagnostic testing. Increased diagnosis of LS allows for surveillance and risk reduction, which can mitigate CRC-related burden and prevent cancer-related deaths. We evaluated participation in LS screening among newly diagnosed adult CRC patients. Some cases were referred for genetics evaluation prior to study recruitment (selective screening). Those not referred directly were randomized to the intervention or control (usual care) arms. Control cases were observed for one year, then given information about LS screening. Patients who declined participation were followed through the medical record. Of 601 cases of CRC, 194 (32%) enrolled in our study and were offered LS screening, 43 (7%) were followed as a control group, 148 (25%) declined participation and 216 (36%) were ineligible [63 (10%) of which received prior selective screening]. Six and nine cases of LS were identified through the intervention and selective screening groups, respectively. Overall, a higher proportion of PMS2 variants were identified in the intervention (3/6, 50%) versus selective screening groups (2/9, 22%) (not statistically significant). Eighty-eight percent and 23% of intervention and control patients, respectively, received LS screening. No control patients were found to have LS. Systems-based approaches are needed to ensure we fully identify LS cases. The proportion of LS cases from this program was 4% of newly diagnosed cases of CRC, similar to other programs.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Testes Genéticos , Desenvolvimento de Programas , Encaminhamento e Consulta/organização & administração , Idoso , Neoplasias Colorretais Hereditárias sem Polipose/genética , Proteínas de Ligação a DNA/genética , Feminino , Testes Genéticos/estatística & dados numéricos , Humanos , Masculino , Programas de Rastreamento/organização & administração , Programas de Rastreamento/estatística & dados numéricos , Pessoa de Meia-Idade , Endonuclease PMS2 de Reparo de Erro de Pareamento/genética , Proteína 1 Homóloga a MutL/genética , Proteína 2 Homóloga a MutS/genética , Encaminhamento e Consulta/estatística & dados numéricos
19.
mBio ; 10(1)2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30808701

RESUMO

All evolutionary processes are underpinned by a cellular capacity to mutate DNA. To identify factors affecting mutagenesis, it is necessary to compare mutation rates between different strains and conditions. Drug resistance-based mutation reporters are used extensively to measure mutation rates, but they are suitable only when the compared strains have identical drug tolerance levels-a condition that is not satisfied under many "real-world" circumstances, e.g., when comparing mutation rates among a series of environmental or clinical isolates. Candida glabrata is a fungal pathogen that shows a high degree of genetic diversity and fast emergence of antifungal drug resistance. To enable meaningful comparisons of mutation rates among C. glabrata clinical isolates, we developed a novel fluorescence-activated cell sorting-based approach to measure the mutation rate of a chromosomally integrated GFP gene. We found that in Saccharomyces cerevisiae this approach recapitulated the reported mutation rate of a wild-type strain and the mutator phenotype of a shu1Δ mutant. In C. glabrata, the GFP reporter captured the mutation rate increases caused either by a genotoxic agent or by deletion of DNA mismatch repair gene MSH2, as well as the specific mutational signature associated with msh2Δ Finally, the reporter was used to measure the mutation rates of C. glabrata clinical isolates carrying different alleles of MSH2 Together, these results show that fluorescence-based mutation reporters can be used to measure mutation rates in microbes under conditions of unequal drug susceptibility to reveal new insights about drivers of mutagenesis.IMPORTANCE Measurements of mutation rates-i.e., how often proliferating cells acquire mutations in their DNA-are essential for understanding cellular processes that maintain genome stability. Many traditional mutation rate measurement assays are based on detecting mutations that cause resistance to a particular drug. Such assays typically work well for laboratory strains but have significant limitations when comparing clinical or environmental isolates that have various intrinsic levels of drug tolerance, which confounds the interpretation of results. Here we report the development and validation of a novel method of measuring mutation rates, which detects mutations that cause loss of fluorescence rather than acquisition of drug resistance. Using this method, we measured the mutation rates of clinical isolates of fungal pathogen Candida glabrata This assay can be adapted to other organisms and used to compare mutation rates in contexts where unequal drug sensitivity is anticipated.


Assuntos
Candida glabrata/genética , Técnicas Microbiológicas/métodos , Biologia Molecular/métodos , Taxa de Mutação , Alelos , Citometria de Fluxo , Genes Reporter , Proteínas de Fluorescência Verde/análise , Proteínas de Fluorescência Verde/genética , Proteína 2 Homóloga a MutS/genética , Mutagênicos/toxicidade , Saccharomyces cerevisiae/genética
20.
Asian Pac J Cancer Prev ; 20(2): 509-517, 2019 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-30803214

RESUMO

Introduction: Microsatellite instability (MSI) is a hallmark of defective DNA mismatch repair (MMR) of genes especially MLH1 and MSH2. It is frequently involved in the carcinogenesis of various tumours including gastric cancer (GC). However, MSI in GCs have not been reported in Malaysia before. Objective: This study was conducted to determine the microsatellite instability (MSI) status in gastric cancer by microsatellite analysis, sequencing, its association with MLH1 and MSH2 protein expression and H.pylori infection by immunohistochemistry. Method: A total of 60 gastric cancer cases were retrieved. DNA was extracted from paired normal and tumour tissues while MLH1 and MSH2 protein expression as well as H. pylori status were determined by IHC staining. For microsatellite analysis, polymerase chain reaction (PCR) was performed for paired tissue samples using a panel of five microsatellite markers. MSI-positive results were subjected for DNA sequencing to assess mutations in the MLH1 and MSH2 genes. Results: Microsatellite analysis identified ten MSI positive cases (16.7%), out of which only six cases (10.3%) showed absence of MLH1 (n=3) or MSH2 (n=3) protein expression by IHC. The most frequent microsatellite marker in MSI positive cases was BAT26 (90%). Nine of ten MSI positive cases were intestinal type with one diffuse and all were located distally. H. pylori infection was detected in 13 of 60 cases (21.7%) including in three MSI positive cases. All these results however were not statistically significant. Our sequencing data displayed novel mutations. However these data were not statistically correlated with expression levels of MLH1 and MSH2 proteins by IHC. This may be due to small sample size to detect small or moderately sized effects. Conclusion: The frequency of MSI in this study was comparable with published results. Determination of affected MMR genes by more than two antibodies may increase the sensitivity of IHC to that of MSI analysis.


Assuntos
Biomarcadores Tumorais/metabolismo , Mutação em Linhagem Germinativa , Instabilidade de Microssatélites , Proteína 1 Homóloga a MutL/metabolismo , Proteína 2 Homóloga a MutS/metabolismo , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismo , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/genética , Estudos de Casos e Controles , Feminino , Seguimentos , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Proteína 1 Homóloga a MutL/genética , Proteína 2 Homóloga a MutS/genética , Prognóstico , Estudos Retrospectivos , Neoplasias Gástricas/patologia , Taxa de Sobrevida
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