RESUMO
Comprehensive next-generation sequencing panels are leading to detection of rare gene fusion events. EFGR-RAD51 fusion is a rare oncogenic finding and clinical data for management of this condition is scarce. We report a widely metastatic non-small cell lung cancer in a never-smoker young male patient with sustained near-complete systemic and intracranial response to osimertinib, a third-generation EGFR tyrosine-kinase inhibitor (TKI). We also review the available data of other TKIs in this scenario and underscore the role of comprehensive molecular testing for NSCLC.
Assuntos
Adenocarcinoma de Pulmão , Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Acrilamidas , Adenocarcinoma de Pulmão/tratamento farmacológico , Adenocarcinoma de Pulmão/genética , Adenocarcinoma de Pulmão/patologia , Compostos de Anilina/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Receptores ErbB/genética , Fusão Gênica , Humanos , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Masculino , Mutação , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Rad51 Recombinase/genéticaRESUMO
PURPOSE: BRCA2 defect exists in glioma and regulates drug resistance of glioma to chemotherapy. However, its role in medulloblastoma and the mechanism is not known. To investigate the effects of BRCA2 deficiency combined with Olaparib in medulloblastoma and the mechanism. METHODS: BRCA2 was knocked down by RNAi technology and cell proliferation was detected by CCK-8 assay. Cell apoptosis was determined by FACS analysis when the in vivo role of BRCA2 was explored with xenograft mice model. Western blotting technology was used to explore the mechanism of BRCA2. RESULTS: Knockdown of BRCA2 enhanced the inhibitory effect of Olaparib on proliferation of Daoy and LN229 cells. The inhibition rate of Olaparib on Daoy or LN229 cells was 61.1%, 66.03% in shBRCA2 group, while it was 42.9%, 41.1% in shNC group. Overexpression of RAD51 partially reversed the effect of shBRCA2. In Daoy cells, apoptotic rate was 26.9% in Olaparib group and 58.9% in Olaparib/shBRCA2 group. However, it was 33.4% after RAD51 was overexpressed. It was the same in LN229 cells. In xenograft mice model, tumor volume in Olaparib and Olaparib/shBRCA2 group was 376.12 and 84.95mm3 when tumor weight was 0.46 g and 0.12 g. In addition, the level of RAD51, RAD50, MRE11, and NBS was increased by Olaparib alone but decreased reversely after knockdown of BRCA2 in Daoy cells. CONCLUSIONS: Knockdown of BRCA2 increases the sensitivity of medulloblastoma cells to Olaparib and strengthens the efficacy of Olaparib in vitro and in vivo. Knockdown of BRCA2 causes DNA damage repair by regulating RAD51-mediated signaling pathway in Daoy cells.
Assuntos
Neoplasias Cerebelares , Glioma , Meduloblastoma , Animais , Proteína BRCA2/genética , Linhagem Celular Tumoral , Neoplasias Cerebelares/tratamento farmacológico , Neoplasias Cerebelares/genética , Dano ao DNA , Reparo do DNA , Humanos , Meduloblastoma/tratamento farmacológico , Meduloblastoma/genética , Camundongos , Ftalazinas , Piperazinas , Rad51 Recombinase/genética , Rad51 Recombinase/metabolismoRESUMO
PURPOSE: Gas station workers (GSWs) are exposed to carcinogenic agents. The aim was to study the association of high somatic chromosome alterations (CAs) rates in the blood of GSWs and the polymorphisms of three genes playing a role in DNA double-strand break repair. METHODS: This is a cross-sectional study with 114 GSWs and 115 age-matched controls. Cytogenetic analyses, blood exams, medical interviews and genotypes for RAD51/G135C (rs1801320), ATM/P1054R (rs1800057) and CHEK2/T470C (rs17879961) genes were performed. RESULTS: The CA rate in GSWs was 9.8 CAs/1000 metaphases, and 19.1% of the workers had > 10 CAs per 1000 metaphases (group two). GSWs had decreased levels of monocytes (P = 0.024) in their blood exams. The number of variant alleles of the RAD51/G135C polymorphism was higher in GSWs (P = 0.011) compared to the controls, and were associated with enhanced number of CAs per worker (P = 0.008). No allele variant was found for CHEK2/T470C in this study. CONCLUSION: The RAD51/G135C polymorphism appears to be related to genome instability in gas station workers. Increasing the knowledge of DNA repair gene variations involved in maintaining genomic stability in GSWs may be crucial for future cancer prevention.
Assuntos
Aberrações Cromossômicas , Reparo do DNA/genética , Gasolina , Exposição Ocupacional , Rad51 Recombinase/genética , Adulto , Proteínas Mutadas de Ataxia Telangiectasia/genética , Brasil , Quinase do Ponto de Checagem 2/genética , Estudos Transversais , Feminino , Genótipo , Humanos , Hibridização in Situ Fluorescente , Masculino , Pessoa de Meia-Idade , Indústria de Petróleo e Gás , Polimorfismo Genético , Adulto JovemRESUMO
The protozoan Trypanosoma cruzi is the causative agent of Chagas disease, a neglected tropical disease that affects around 8 million people worldwide. Chagas disease can be divided into two stages: an acute stage with high parasitemia followed by a low parasitemia chronic stage. Recently, the importance of dormancy concerning drug resistance in T. cruzi amastigotes has been shown. Here, we quantify the percentage of dormant parasites from different T. cruzi DTUs during their replicative epimastigote and amastigote stages. For this study, cells of T. cruzi CL Brener (DTU TcVI); Bug (DTU TcV); Y (DTU TcII); and Dm28c (DTU TcI) were used. In order to determine the proliferation rate and percentage of dormancy in epimastigotes, fluorescent-labeled cells were collected every 24 h for flow cytometer analysis, and cells showing maximum fluorescence after 144 h of growth were considered dormant. For the quantification of dormant amastigotes, fluorescent-labeled trypomastigotes were used for infection of LLC-MK2 cells. The number of amastigotes per infected LLC-MK2 cell was determined, and those parasites that presented fluorescent staining after 96 h of infection were considered dormant. A higher number of dormant cells was observed in hybrid strains when compared to non-hybrid strains for both epimastigote and amastigote forms. In order to investigate, the involvement of homologous recombination in the determination of dormancy in T. cruzi, we treated CL Brener cells with gamma radiation, which generates DNA lesions repaired by this process. Interestingly, the dormancy percentage was increased in gamma-irradiated cells. Since, we have previously shown that naturally-occurring hybrid T. cruzi strains present higher transcription of RAD51-a key gene in recombination process -we also measured the percentage of dormant cells from T. cruzi clone CL Brener harboring single knockout for RAD51. Our results showed a significative reduction of dormant cells in this T. cruzi CL Brener RAD51 mutant, evidencing a role of homologous recombination in the process of dormancy in this parasite. Altogether, our data suggest the existence of an adaptive difference between T. cruzi strains to generate dormant cells, and that homologous recombination may be important for dormancy in this parasite.
Assuntos
Recombinação Homóloga , Trypanosoma cruzi/genética , Trypanosoma cruzi/fisiologia , Animais , Linhagem Celular , Macaca mulatta , Mutação , Proteínas de Protozoários/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Protozoário/genética , Rad51 Recombinase/genética , Especificidade da Espécie , Trypanosoma cruzi/citologia , Trypanosoma cruzi/crescimento & desenvolvimentoRESUMO
BACKGROUND: This study investigated the influence of single nucleotide polymorphisms (SNP) in RAD51 and XRCC3 on susceptibility to oral and oropharyngeal squamous cell carcinomas (SCC) and determined their clinicopathological significance. SUBJECTS AND METHODS: SNPs rs1801320 and rs1801321 in RAD51 and rs861539 in XRCC3 were genotyped in 81 patients presenting oral SCC, 45 presenting oropharyngeal SCC, and 130 healthy controls, using TaqMan allelic discrimination assays. Multiple logistic regression models were used to explore the association between SNPs and cancer development, as well as gene-gene (GxG) interaction and gene-environmental factor (GxE) interaction. Clinicopathological associations were verified through the chi-square test, and univariate and multivariate methods were applied for survival analyses. RESULTS: Although allelic and genotypic models and the GxG interaction analysis were nonsignificant, the GxE analysis revealed synergistic effects of the risk alleles of rs1801320, rs1801321, and rs861539 with smoking and alcohol consumption on susceptibility to oral and oropharyngeal SCC. Furthermore, oropharyngeal SCC patients carrying the XRCC3 rs861539 GT/TT genotype (T risk allele) presented a shorter overall survival than GG genotype carriers. CONCLUSION: Combined effects of RAD51 (rs1801320 and rs1801321) and XRCC3 (rs861539) SNPs with environmental carcinogens (tobacco and alcohol) are associated with oral and oropharyngeal SCC development.
Assuntos
Carcinoma de Células Escamosas/genética , Proteínas de Ligação a DNA/genética , Predisposição Genética para Doença , Neoplasias Orofaríngeas/genética , Polimorfismo de Nucleotídeo Único , Rad51 Recombinase/genética , Consumo de Bebidas Alcoólicas/efeitos adversos , Alelos , Carcinoma/genética , Estudos de Casos e Controles , Genótipo , Humanos , Fatores de Risco , Fumar/efeitos adversosRESUMO
In Trypanosoma cruzi, the etiologic agent of Chagas disease, Rad51 (TcRad51) is a central enzyme for homologous recombination. Here we describe the different roles of TcRad51 in DNA repair. Epimastigotes of T. cruzi overexpressing TcRAD51 presented abundant TcRad51-labeled foci before gamma irradiation treatment, and a faster growth recovery when compared to single-knockout epimastigotes for RAD51. Overexpression of RAD51 also promoted increased resistance against hydrogen peroxide treatment, while the single-knockout epimastigotes for RAD51 exhibited increased sensitivity to this oxidant agent, which indicates a role for this gene in the repair of DNA oxidative lesions. In contrast, TcRad51 was not involved in the repair of crosslink lesions promoted by UV light and cisplatin treatment. Also, RAD51 single-knockout epimastigotes showed a similar growth rate to that exhibited by wild-type ones after treatment with hydroxyurea, but an increased sensitivity to methyl methane sulfonate. Besides its role in epimastigotes, TcRad51 is also important during mammalian infection, as shown by increased detection of T. cruzi cells overexpressing RAD51, and decreased detection of single-knockout cells for RAD51, in both fibroblasts and macrophages infected with amastigotes. Besides that, RAD51-overexpressing parasites infecting mice also presented increased infectivity and higher resistance against benznidazole. We thus show that TcRad51 is involved in the repair of DNA double strands breaks and oxidative lesions in two different T. cruzi developmental stages, possibly playing an important role in the infectivity of this parasite.
Assuntos
Quebras de DNA de Cadeia Dupla , Reparo do DNA , Proteínas de Protozoários/metabolismo , Rad51 Recombinase/metabolismo , Trypanosoma cruzi/enzimologia , Trypanosoma cruzi/genética , Animais , Doença de Chagas/parasitologia , Quebras de DNA de Cadeia Dupla/efeitos da radiação , Reparo do DNA/efeitos da radiação , Humanos , Masculino , Camundongos , Estresse Oxidativo , Proteínas de Protozoários/genética , Rad51 Recombinase/genética , Trypanosoma cruzi/metabolismo , Trypanosoma cruzi/efeitos da radiação , Raios UltravioletaRESUMO
Detection of genetic exchange has been a limiting factor to deepen the knowledge on the mechanisms by which Trypanosoma cruzi is able to generate progeny and genetic diversity. Here we show that incorporation of halogenated thymidine analogues, followed by immunostaining, is a reliable method not only to detect T. cruzi fused-cell hybrids, but also to quantify their percentage in populations of this parasite. Through this approach, we were able to detect and quantify fused-cell hybrids of T. cruzi clones CL Brener and Y. Given the increased detection of fused-cell hybrids in naturally-occurring hybrid CL Brener strain, which displays increased levels of RAD51 and BRCA2 transcripts, we further investigated the role of Rad51 - a recombinase involved in homologous recombination - in the process of genetic exchange. We also verified that the detection of fused-cell hybrids in T. cruzi overexpressing RAD51 is increased when compared to wild-type cells, suggesting a key role for Rad51 either in the formation or in the stabilization of fused-cell hybrids in this organism.
Assuntos
Recombinação Homóloga/fisiologia , Proteínas de Protozoários/metabolismo , Rad51 Recombinase/metabolismo , Trypanosoma cruzi/enzimologia , Proteínas de Protozoários/genética , Rad51 Recombinase/genética , Trypanosoma cruzi/genéticaRESUMO
Mutations in FMS-like tyrosine kinase 3 (FLT3), such as internal tandem duplications (ITDs), can be found in up to 23% of patients with acute myeloid leukemia (AML) and confer a poor prognosis. Current treatment options for FLT3(ITD)-positive AMLs include genotoxic therapy and FLT3 inhibitors (FLT3i's), which are rarely curative. PARP1 inhibitors (PARP1i's) have been successfully applied to induce synthetic lethality in tumors harboring BRCA1/2 mutations and displaying homologous recombination (HR) deficiency. We show here that inhibition of FLT3(ITD) activity by the FLT3i AC220 caused downregulation of DNA repair proteins BRCA1, BRCA2, PALB2, RAD51, and LIG4, resulting in inhibition of 2 major DNA double-strand break (DSB) repair pathways, HR, and nonhomologous end-joining. PARP1i, olaparib, and BMN673 caused accumulation of lethal DSBs and cell death in AC220-treated FLT3(ITD)-positive leukemia cells, thus mimicking synthetic lethality. Moreover, the combination of FLT3i and PARP1i eliminated FLT3(ITD)-positive quiescent and proliferating leukemia stem cells, as well as leukemic progenitors, from human and mouse leukemia samples. Notably, the combination of AC220 and BMN673 significantly delayed disease onset and effectively reduced leukemia-initiating cells in an FLT3(ITD)-positive primary AML xenograft mouse model. In conclusion, we postulate that FLT3i-induced deficiencies in DSB repair pathways sensitize FLT3(ITD)-positive AML cells to synthetic lethality triggered by PARP1i's. Therefore, FLT3(ITD) could be used as a precision medicine marker for identifying AML patients that may benefit from a therapeutic regimen combining FLT3 and PARP1i's.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Reparo do DNA/efeitos dos fármacos , Leucemia Mieloide Aguda , Poli(ADP-Ribose) Polimerase-1/antagonistas & inibidores , Tirosina Quinase 3 Semelhante a fms/metabolismo , Animais , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Proteína BRCA2/genética , Proteína BRCA2/metabolismo , Benzotiazóis/farmacologia , Linhagem Celular Tumoral , DNA Ligase Dependente de ATP/genética , DNA Ligase Dependente de ATP/metabolismo , Proteína do Grupo de Complementação N da Anemia de Fanconi/genética , Proteína do Grupo de Complementação N da Anemia de Fanconi/metabolismo , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patologia , Camundongos , Mutação , Compostos de Fenilureia/farmacologia , Ftalazinas/farmacologia , Piperazinas/farmacologia , Poli(ADP-Ribose) Polimerase-1/genética , Poli(ADP-Ribose) Polimerase-1/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Rad51 Recombinase/genética , Rad51 Recombinase/metabolismo , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto , Tirosina Quinase 3 Semelhante a fms/genéticaRESUMO
Resveratrol (RES), a polyphenol compound with antiproliferative properties, has been previously evaluated for its beneficial effects against a variety of tumour cells. The current study elucidated the means by which RES enhances the antiproliferative effects of cisplatin (CIS) on MCF7 cells, focusing on the inhibitory effects on DNA repair of doublestrand breaks (DSBs). Chemoresistant MCF7 cells (MCF7R) were generated by continuous exposure to low concentrations of CIS (10 µM CISIC40) during 5 passages, with the IC50 value increasing ~3fold. Using an MTT assay, we estimated the changes in IC50 for CIS in MCF7, T47D, MDAMB231 and MCF7R cells in the presence of RES. The relative transcript level of Nbs1, Mre11 and Rad50 genes was assessed using RTqPCR analysis. Rad51 and H2AX [pSer139] protein expression was determined by western blot analysis. RES at 50 and 100 µM significantly enhanced the antiproliferative effects of CIS in both MCF7 and MCF7R cells, decreasing the IC50 values for CIS to onetenth and onesixth, respectively. A total of 100 µM RES decreased the relative transcript levels of homologous recombination (HR) initiation complex components and the Rad51 protein level in MCF7 and MCF7R cells. After 48 h of CIS DNA damage, the levels of Rad51 protein increased, but this effect was inhibited by 100 µM RES. RES also maintained serine 139 phosphorylation of histone H2AX, suggesting that RES prevents the repair of DSBs. It was observed that RES exerts an antagonistic effect over CIS on the activation of Rad51 and sustained phosphorylation of H2AX. The results suggest that RES in combination with DNA damagebased therapy has potential as a strategy to overcome resistance and provide much safer and more effective treatment for breast cancer.
Assuntos
Neoplasias da Mama/genética , Cisplatino/farmacologia , Regulação para Baixo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Rad51 Recombinase/genética , Estilbenos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Histonas/metabolismo , Humanos , Células MCF-7 , Fosforilação/efeitos dos fármacos , Rad51 Recombinase/metabolismo , ResveratrolRESUMO
Homologous recombination (HR) is a highly conserved pathway for the repair of chromosomes that harbor DNA double-stranded breaks (DSBs). The recombinase RAD51 plays a key role by catalyzing the pairing of homologous DNA molecules and the exchange of information between them. Two putative DMC1 homologs (DMC1A and DMC1B) have been identified in Giardia duodenalis. In terms of sequences, GdDMC1A and GdDMC1B bear all of the characteristic recombinase domains: DNA binding domains (helix-turn-helix motif, loops 1 and 2), an ATPcap and Walker A and B motifs associated with ATP binding and hydrolysis. Because GdDMC1B is expressed at the trophozoite stage and GdDMC1A is expressed in the cyst stage, we cloned the giardial dmc1B gene and expressed and purified its protein to determine its activities, including DNA binding, ATP hydrolysis, and DNA strand exchange. Our results revealed that it possessed these activities, and they were modulated by divalent metal ions in different manners. GdDMC1B expression at the protein and transcript levels, as well as its subcellular localization in trophozoites upon DNA damage, was assessed. We found a significant increase in GdDMC1B transcript and protein levels after ionizing radiation treatment. Additionally, GdDMC1B protein was mostly located in the nucleus of trophozoites after DNA damage. These results indicate that GdDMC1B is the recombinase responsible for DSBs repair in the trophozoite; therefore, a functional Rad51 role is proposed for GdDMC1B.