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ABSTRACT BACKGROUND: Part of colorectal cancer cases occurs due to modifications in the DNA mismatch repair system, which are responsible for microsatellite instability. This alteration results in an unconventional phenotypic pattern of colorectal cancer. AIMS: To describe the epidemiological, histopathological and molecular profiles of patients with colorectal cancer who underwent surgical treatment in a reference hospital. METHODS: This is a cross-sectional, retrospective study with a quantitative approach, that included a review of patients' medical records who underwent oncological surgery for colorectal cancer. RESULTS: A total of 122 colorectal cancer cases were identified, with microsatellite instability detected in 8.2% of the sample. The gender distribution was similar, with 52.46% males, and the weighted average age was 63 years (standard deviation±11.65). However, in the microsatellite instability group, the predominant age was below 60 years. Regarding the histological type, adenocarcinoma not otherwise specified accounted for 80.33% of the cases, being the most prevalent in both groups, with the mucinous type being more frequent among the instability cases. The pT3 pathological staging (46.72%) was the most predominant. The topography was more prevalent on the left (60.66%), but there was a significant difference when compared to the group with microsatellite instability, in which 80% of the neoplasms were located on the right (p=0.006). CONCLUSIONS: Differences in age and neoplastic topography found in microsatellite instability samples highlight the distinctive presentation pattern of the disease. Recognizing these characteristics is essential for developing prevention strategies, in addition to early and accurate diagnosis of colorectal cancer.
RESUMO RACIONAL: Parte dos casos de câncer colorretal ocorre devido a alterações nas enzimas de reparo do DNA, responsáveis pela instabilidade de microssatélites. Esta alteração resulta em um padrão fenotípico não convencional de câncer colorretal. OBJETIVOS: Descrever os aspectos epidemiológicos, histopatológicos e moleculares dos pacientes com câncer colorretal submetidos a tratamento cirúrgico em hospital de referência. MÉTODOS: Trata-se de um estudo transversal, retrospectivo com abordagem quantitativa, com revisão de prontuários médicos de pacientes submetidos a cirurgia oncológica por câncer colorretal. RESULTADOS: Foram registrados 122 casos de câncer colorretal, com instabilidade de microssatélites detectada em 8,2% da amostra. A distribuição por sexo foi semelhante, sendo 52,46% do sexo masculino, e média ponderada de idade de 63 anos (±11,65), contudo no grupo com instabilidade, a faixa etária predominante foi abaixo de 60 anos. Em relação ao tipo histológico, o adenocarcinoma sem outra especificação representou 80,33% dos casos, sendo o mais prevalente em ambos os grupos, mas com maior frequência do tipo mucinoso em caso de instabilidade. O estadiamento patológico pT3 (46,72%) foi predominante. A topografia da neoplasia foi mais prevalente à esquerda (60,66%), mas houve diferença significativa em relação ao grupo com instabilidade de microssatélites, no qual 80% das neoplasias localizavam-se à direita (p=0,006019). CONCLUSÕES: As diferenças de idade e topografia neoplásica encontradas nas amostras com instabilidade de microssatélites destacam o padrão não habitual de apresentação da doença. O conhecimento, portanto, dessas distinções é necessário para o desenvolvimento de estratégias de prevenção, além de diagnóstico precoce e preciso do câncer colorretal.
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Objective:To analyze the phenotypes and genetic etiology of microcephaly- seizures-development delay (MCSZ) syndrome.Methods:The patient was diagnosed with MCSZ syndrome in June 2018 at Shenzhen Maternity and Child Healthcare Hospital. She was the couple's first child, and the mother conceived a second child in 2020. The clinical data of the proband were retrospectively analyzed, and the bioinformatics analysis and whole-exome sequencing (WES) were performed on the proband and her parents to identify the pathogenic variants, which were further validated using Sanger sequencing. The prenatal genetic diagnosis of the second fetus was performed following the molecular diagnosis of the proband was confirmed. The clinical manifestations and pathogenesis of MCSZ syndrome were summarized by reviewing related literature.Results:(1) Case report: The patient, an eight-month-old girl, was admitted to our hospital due to microcephaly and repeated seizures. Another clinical characteristic was mental retardation. Auditory evoked potential detected moderate impairment of the left auditory nerve pathway. WES showed a compound heterozygous variation in the PNKP gene of the proband. Moreover, the pathogenic variation, c.199-10_203delinsTCTGAGGGGT, was inherited from the father, and the likely pathogenic variation, c.1505C>T(p.P502>L), was inherited from the mother, which was both de novo mutations. The compound heterozygous variation in the PNKP gene was considered genetic etiology based on the genetic testing and clinical features. Prenatal diagnosis showed that the second fetus did not inherit the PNKP gene variants from the parents and the couples chose to continue the pregnancy. A girl was born, and her psychomotor development and occipitofrontal size circumference were normal at 13 months old. (2) Literature review: 39 MCSZ syndrome cases were retrieved, including the present case and 38 cases from 12 relevant literature. The clinical characteristics were microcephaly (91.7%, 33/36), seizures (88.2%, 30/34), development delay (96.4%, 27/28), hyperactivity (25.6%, 9/39), gastroesophageal reflux (10.3%, 4/39), and hearing loss (7.7%, 3/39). Most patients' first onset of epilepsy was in infancy (96.3%, 26/27). Cranial MRI examination showed brain dysplasia in 31 cases (91.2%, 31/34). Conclusions:When the fetal head circumference is smaller than normal and is progressively reduced combined with postnatal microcephaly, epilepsy, developmental retardation, hyperactivity disorder, gastroesophageal reflux, and hearing loss, MCSZ syndrome should be considered. The prognosis varies widely, and genetic testing facilitates the early diagnosis and genetic counseling of MCSZ syndrome.
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Resumo Fundamento A doxorrubicina (DOX) é frequentemente usada para tratar muitos tipos de cânceres, apesar da cardiotoxicidade dose-dependente. Como alternativa, o resveratrol é um polifenol que tem demonstrado efeitos cardioprotetores em vários modelos de disfunção cardíaca. Objetivo Este estudo investigou se o tratamento com resveratrol em ratas gestantes protege contra toxicidade induzida por doxorrubicina em cardiomiócitos da ninhada. Métodos Ratas Wistar (n-8) receberam sresveratrol como suplemento alimentar durante a gestação. No nascimento da ninhada, os corações (9-11) foram usados para se obter a cultura primária de cardiomiócitos. A cardiotoxicidade induzida por DOX e os efeitos da suplementação com resveratrol foram avaliados por marcadores de stress oxidativo, tais como oxidação da diclorofluoresceína diacetato, diminuição da atividade de enzimas antioxidantes, e oxidação do teor total de grupos sulfidrila, além da avaliação da viabilidade celular, geração de danos ao DNA, bem como a resposta de reparo aos danos ao DNA. Um valor de p <0,05 foi considerado estatisticamente significativo. Resultados Os cardiomiócitos de neonatos de ratas que receberam suplemento resveratrol apresentaram um aumento (p <0,01) na viabilidade das células, e diminuição (p <0,0001) de células apoptóticas/necróticas após o tratamento com DOX, o que está correlacionado às atividades de enzimas antioxidantes e produção de diclorofluoresceína. Além disso, o resveratrol protegeu os cardiomiócitos de danos ao DNA induzidos por DOX, apresentando uma diminuição (p <0,05) nas quebras de DNA induzidas por stress oxidativo, avaliadas pela atividade de enzimas reparadoras do DNA endonuclease III e formamidopirimidina glicosilase. A suplementação com resveratrol aumentou (p <0,05) a expressão da proteína reparadora Sirt6 nos cardiomiócitos dos filhotes. Conclusão Essa pesquisa indica que a suplementação com resveratrol durante o período gestacional tem um efeito cardioprotetor no coração da ninhada contra a toxicidade induzida por DOX, o que pode se dever a sua função antioxidante, e o aumento na resposta de danos ao DNA.
Abstract Background Doxorubicin (DOX) is frequently used to treat many types of cancers, despite its dose-dependent cardiotoxicity. Alternatively, resveratrol is a polyphenol that has shown useful cardioprotective effects in many heart dysfunction models. Objective This study investigated whether resveratrol treatment in pregnant rats protects against doxorubicin-induced toxicity in offspring cardiomyocytes. Methods Wistar rats (n=8) were supplemented with dietary resveratrol during pregnancy. Upon the offspring's birth, hearts (9-11) were used to obtain the primary culture of cardiomyocytes. DOX-induced cardiotoxicity and the effects of resveratrol supplementation were evaluated by oxidative stress markers, such as dichlorofluorescein diacetate oxidation, decrease in the activity of antioxidant enzymes, and oxidation of total sulfhydryl content, in addition to cell viability evaluation, DNA damage generation, and DNA damage repair response. A value of p<0.05 was considered statistically significant. Results Neonatal cardiomyocytes from resveratrol supplemented rats exhibiting an increase (p<0.01) in cell viability and lower (p<0.0001) apoptotic/necrotic cells after DOX treatment, which correlates with the activities of antioxidant enzymes and dichlorofluorescein production. Moreover, resveratrol protected cardiomyocytes from DOX-induced DNA damage, showing a decrease (p<0.05) in DNA breaks induced by oxidative stress, evaluated by the activity of DNA-repair enzymes endonuclease III and formamidopyrimidine glycosylase. Supplementation with resveratrol increased (p<0.05) the expression of the repair protein Sirt6 in the cardiomyocytes of the pups. Conclusion This research indicates that supplementation with resveratrol during the gestational period has a notable cardioprotective effect on the offspring's heart against DOX-induced toxicity, which may well be due to its antioxidant function, and the increase in the DNA damage repair response.
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Animals , Female , Pregnancy , Rats , Doxorubicin/toxicity , Myocytes, Cardiac , Rats, Wistar , Dietary Supplements , Resveratrol/pharmacologyABSTRACT
Objective To identify if there was increased DNA damage in cardiomyocytes of rats with diabetic cardiomyopathy and also to evaluate the change in gene expression of DNA repair enzymes 8-oxoguanine DNA glycosylase 1(OGG1) and AP endonuclease 1(APE1).Methods Total DNA,RNA and proteins of hearts were isolated in diabetes rat hearts.DNA damage was examined with quantitative polymerase chain reaction(Q-PCR) assay.mRNA and protein expressions of OGG1 and APE1 were detected with real time-polymerase chain reaction(RT-qPCR) and Western blot analysis.The levels of 8-hydroxy-2′-deoxy-guanosine(8-OHdG) in DNA were studied with ELISA.ResultsThe damage of mtDNA was increased in rat hearts(P<0.05) and there was not significant damage in nDNA.The amount of 8-OHdG in DNA was significantly increased(P<0.05),mRNA and protein expressions of OGG1 and APE1 were increased in diabetic rat hearts(P<0.01).Conclusions The damage of mtDNA increased in diabetic rat hearts.Although the expression of OGG1 and APE1 increased in diabetic rat hearts,which fails to repair the damage of the mtDNA.The increased mtDNA damage may contributes to myocardium damage.
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Objective To investigate changes in the expression of apurinic/apyrimidinic endonuclease (APE) and the oxidative DNA damage marker 8 OHdG in distant hippocampus regions of the rat brain after focal cerebral ischemia of the middle cerebral artery.Methods SD rats were divided into the sham surgery group and the pMCAO group (induced by middle cerebral artery occlusion).Pathological changes in brain tissues were examined at 2 h,6 h,12 h,24 h,48 h and 72 h.The expression of APE and 8-OHdG was measured by immunohistochemical staining methods.TUNEL staining was performed to detect apoptosis.Results Reduction of APE expression in the CA1 region of the hippocampus on the ischemia side appeared at 2 h in the pMCAO group and continued as ischemia persisted (F=11.91,P＜0.05).The expression of 8OHdG and TUNEL immunoreactivity in the CA1 region of the hippocampus on the ischemia side were first observed at 6h in the pMCAO group and intensified during the remainder of induced ischemia (F=9.23 and 10.46 respectively,P＜0.05 for both).Compared with the sham group,8-OHdG expression and TUNEL immunoreactivity in the pMCAO group were at nearly the same levels from 24 h to 72h.Conclusions Oxidative DNA damage occurs in hippocampus regions of the rat brain after experimentally induced focal cerebral ischemia of the middle cerebral artery.APE expression declines in regions distant from focal cerebral ischemia.Development and accumulation of oxidative DNA damage can induce apoptosis in certain brain regions.
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DNA polymerase iota (Polt),as well as Revl,Polκ and Polη,are all Y family DNA polymerases,which are able to replicate damaged DNA via translesion synthesis pathway.However,Pol(t) has the lowest fidelity among all DNA polymerases in both correct and inaccurate DNA templates.Also Pol(t) can bypass certain DNA damages and accumulate mutations.Recent studies show that the aberrant expression of Pol(t) is observed in human uveal melanoma,breast cancer,bladder cancer,lung cancer and esophageal cancer,which may contribute to the tumorigenesis and progression of tumor.The special role of Pol(t) in replicating damaged DNA may contribute to the resistance in oncotherapy.
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Poly ADP ribose polymerases (PARP) play an important role in DNA damage repair and genome stability.So,PARP inhibitors can inhibit the DNA damage repairing of tumor cells and enhance the sensitivity of the DNA of tumor cells to damage factors.In recent years,PARP inhibitors have been more and more concerned.PARP inhibitors can kill tumor cells with certain genetic mutations alone by synthetic lethal effect.In addition,PARP inhibitors in combination with chemotherapy or radiotherapy can increase the sensi tivity of tumor cells to the chemotherapy or radiotherapy.PARP inhibitors are expected to play an important role in cancer therapy.
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Poly( ADP-ribose) polymerase 1 (PARP-1) plays an essential role in DNA repair and maintenance of homeostasis and genome stability. Increased PARP-1 activity has been reported in various forms of cancer. Thus the absence of PARP-1 or the use of its inhibitors depresses DNA repair function, sensitizes cancer cells to DNA damage and enhances the therapeutic effect of radio-or chemotherapy. PARP-1 is potentially a therapeutic target of malignant tumors.
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Objective: To investigate the association of DNA X-ray repair cross complementary protein 1 (XRCC1) Arg399Gln polymorphism with the clinical outcome of gastric cancer patients treated with platinum-based chemotherapy. Methods: Eight-four patients with gastric cancer confirmed by pathological examination received postoperative combined chemotherapy (including platinum). Transcription of XRCC1 Arg399Gln was determined by polymerase chain reaction-ligation detection reaction (PCR-LDR). Results: Of the 84 patients, the frequencies of XRCC1 codon 399 Arg/Arg, Arg/Gln, and Gln/Gln genotype were 58.3% (49/84), 35.7% (30/84), and 6.0% (5/84), respectively; and the relapse and death rate were 63.1% (53/ 84) and 55.2% (43/84), respectively. The relapse and death rates in patients with Arg/Arg genotype were significantly lower than those in patients with Arg/Gln or Gln/Gln genotypes (P < 0.05). COX multivariate analysis showed that XRCC1 Arg399Arg polymorphism was associated with better recurrence-free and overall survival in gastric cancer patients compared with other genotypes (P < 0.05). Conclusion: Polymorphism of XRCC1 Arg399Gln correlated with the prognosis of gastric cancer patients treated with postoperative platinum-based chemotherapy. It may be helpful to a certain extent for evaluating the prognosis.
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Objective: To explore the correlation between the expressions of DSB (DNA double-strand break) repair protein (including Ku80, DNA-PKcs, and ATM) and radiosensitivity parameters of human tumor cell lines, and to reveal the value of the three proteins for the prognosis of the radiosensitivity of tumor cells. Methods: Eight tumor cell lines were selected including four human cervical carcinoma cell lines (HeLa, SiHa, C33A, and Caski), three human breast carcinoma cell lines (MCF-7, MDA-MB-231, MDA-MB453), and one human lung carcinoma cell line (A549). The expressions of Ku80, DNA-PKcs and ATM protein were measured by Western blotting. The apoptotic ratio of tumor cells was analyzed by flow cytometry after 48 h X-ray irradiation at 10 Gy of 6 MV. SF2 value (survival fraction at 2 Gy) and α and β values were obtained by clone formation assay. The correlation of protein expression with SF2, α/β value or apoptotic ratio was analyzed by Pearson linear correlation analysis. Results: The expression of same protein in different cell lines and the expression of the three proteins in the same cell line had significant difference. There was a positive correlation between the expression of DNA-PKcs and SF2 (r=0.723, P=0.043 0.05). The expression of the three proteins had no correlation with either apoptotic ratio or α/ β value (P>0.05). Conclusions: Tumor cells with higher expression of DNA-PKcs protein will have higher radioresistance. The expression level of DNA-PKcs protein in tumor cells may be an indicator for predicting the radiosensitivity of tumor cells.
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Objective: To investigated the expressions of ERCC1, RRM1 and BRCA1 (members of DNA repair gene family) in patients with non-small cell lung cancer (NSCLC) as well as their clinical prognostic significance. Methods: Expression levels of ERCC1, RRM1 and BRCA1 were detected by real-time PCR method in 32 NSCLC patients and 16 cases of adjacent normal lung tissues. Wilcoxon signed-rank test, Wilcoxon rank sum test, rank correlation, Kaplan-Meier survival curve, and COX multivariate regression analysis were used for statistical analysis. Results: The expression levels of ERCC1, RRM1 and BRCA1 were significantly higher in lung cancer tissues than that in adjacent normal lung tissues. There were significant correlations between intratumoral expression of ERCC1, RRM1, and BRCA1. RRM1 expression level was significantly higher in lung squamous cell carcinomas compared with lung adenocarcinomas but had no difference between different clinical stages. The expression of ERCC1 and BRCA1 had no difference between different pathological classification and clinical TNM stages. The patients with high expression of RRM1 and BRCA1 had significant longer survival time than those with low expression of RRM1 and BRCA1. COX multivariate regression analysis showed that expression of RRM1 was an independent prognostic factor for NSCLC. Conclusion: The expression levels of ERCCI, RRM1, and BRCA1 are significantly higher in lung cancer tissues than that of adjacent normal lung tissues. The patients with high expression of RRM1 and BRCA1 had significant longer survival time than those with low expression of RRM1 and BRCA1. RRM1 and BRCA1 mRNA expressions can be used to predict prognosis of NSCLC.
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To evaluate the relationship of genetic polymorphisms of ERCC2 and ERCC4 genes, both involved in nucleotide excision repair (NER), and the risk of breast cancer, a hospital-based case-control study was conducted in Korea. Histologically confirmed breast cancer cases (n=574) and controls (n=502) with no present or previous history of cancer were recruited from three teaching hospitals in Seoul during 1995-2001. Information on selected characteristics was collected by interviewed questionnaire. ERCC2 Asp312Asn (G>A) was genotyped by single-base extension assay and ERCC4 Ser835Ser (T>C) by dynamic allele-specific hybridization system. Although no significant association was observed between the genetic polymorphisms and the risk of breast cancer, women with both ERCC2 A allele- and ERCC4 C allele-containing genotypes showed a 2.6-fold risk (95% CI: 1.02-6.48) of breast cancer compared to women concurrently carrying the ERCC2 GG and ERCC4 TT genotypes. The breast cancer risk increased as the number of "at risk" genotypes increased with a borderline significance (P for trend = 0.07). Interactive effect was also observed between ERCC4 genotype and body mass idnex (BMI) for the breast cancer risk; the ERCC4 C allele containing genotypes posed a 1.7-fold (95% CI: 0.96-2.93) breast cancer risk in obese women (BMI>25 kg/m2) with a borderline significance. Our finding suggests that the combined effect of ERCC2 Asp312Asn and ERCC4 Ser835Ser genotypes might be associated with breast cancer risk in Korean women.
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Female , Humans , Middle Aged , Breast Neoplasms/genetics , DNA Helicases/genetics , DNA-Binding Proteins/genetics , Genetic Predisposition to Disease , Korea , Obesity/genetics , Polymorphism, Genetic , Transcription Factors/geneticsABSTRACT
The p53 tumor suppressor has long been envisaged to preserve genetic stability by the induction of cell cycle checkpoints and apoptosis. More recently, p53 has been implicated to play roles in DNA repair responses to genotoxic stresses. UV-damage and the damage caused by certain chemotherapeutics including cisplatin and nitrogen mustards are known to be repaired by the nucleotide excision repair (NER) pathway which is reportedly regulated by p53 and its downstream genes. There are evidences to suggest that the base excision repair (BER) induced by the base-damaging agent methyl methanesulfonate (MMS) is partially deficient in cells lacking functional p53. This result suggests that the activity of BER might be also dependent on the p53 status. In this review, we discuss the possibilities that p53 regulates BER as well as NER; these are one of the most significant potentials of p53 tumor suppressor for repairing the vast majority of DNA damages that is incurred from various environmental stresses.
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Animals , Humans , Mice , Antineoplastic Agents/pharmacology , DNA/drug effects , DNA Damage , DNA Repair/physiology , Tumor Suppressor Protein p53/physiologyABSTRACT
Large doses of acetaminophen (APAP) could cause oxidative stress and tissue damage through production of reactive oxygen/nitrogen (ROS/RNS) species and quinone metabolites of APAP. Although ROS/RNS are known to modify DNA, the effect of APAP on DNA modifications has not been studied systematically. In this study, we investigate whether large doses of APAP can modify the nuclear DNA in C6 glioma cells used as a model system, because these cells contain cytochrome P450-related enzymes responsible for APAP metabolism and subsequent toxicity (Geng and Strobel, 1995). Our results revealed that APAP produced ROS and significantly elevated the 8-oxo- deoxyguanosine (8-oxodG) levels in the nucleus of C6 glioma cells in a time and concentration dependent manner. APAP significantly reduced the 8- oxodG incision activity in the nucleus by decreasing the activity and content of a DNA repair enzyme, Ogg1. These results indicate that APAP in large doses can increase the 8-oxodG level partly through significant reduction of Ogg1 DNA repair enzyme.