Mecanismos envolvidos na progressão do câncer de ovário : 1) papel de NAC1 e BCL6 na regulação da expressão gênica; 2) efeito da cisplatina no fenótipo de células-tronco tumorais, migração e quimiorresistência

Ovarian cancer (OVCA) is the most lethal gynecological cancer, and its dissemination and chemoresistance are major factors determining disease prognosis. Better understanding of mechanisms involved in these processes is crucial to improve OVCA therapy; therefore being the aim of the present study. Firstly, the role of NAC1 and BCL6 regulating transcription in OVCA has been investigated using FOXQ1 as a study model. It has been shown that NAC1 and BCL6 interact through NAC1’s BEN C-terminus domain, forming a complex which binds to three BCL6 binding motives on FOXQ1 promoter, activating its transcription. A positive correlation between NAC1 and BCL6 expression has been shown in OVCA cell lines and tumor specimens. Moreover, BCL6-depending NAC1 binding to BCL6 promoter activating its transcription has been shown. Therefore, a novel mechanism by which a BTB/POZ family member interacts with BCL6 attenuating its auto-repression has been herein described. Finally, cDNA microarray analyzes revealed a plethora of putative NAC1/BCL6 target genes. On the second chapter, the effects of cisplatin on OVCA progression have been analyzed. It has been shown that a five-day treatment with 10-5M cisplatin of A2780 cell increased chemoresistance, cell migration and expression of the cancer-stem cell associated phenotype CD44+CD24-, and a G2/M cell cycle arrest. The secretion of TGF-β1 and CXCL2, both cytokines involved in migration and resistance in cancer, in response to cisplatin, doxorubicin, and paclitaxel, by three cell lines originated from serous (A2780), endometrioid (MDAH-2774), and clear cell (TOV21G) OVCA subtypes has been measured. In response to cisplatin, TGF-β1 secretion by TOV21G cells has increased, as has CXCL2 secretion by TOV21G and A2780. When analyzing the effect of exogenous CXCL2 in drug resistance, this relation could not be demonstrated. However, it could be explained by CXCR2 overexpression in response to cisplatin, which has been herein demonstrated. Therefore, several different mechanisms leading to OVCA progression have been identifiedO câncer de ovário (CAOV) é a neoplasia ginecológica mais letal, sendo que a disseminação da doença e a quimiorresistência podem ser considerados fatores determinantes no prognóstico da doença. O entendimento dos mecanismos envolvidos nesses processos é essencial ao aprimoramento da terapêutica do CAOV, sendo assim o alvo de estudo deste trabalho. Primeiramente, investigou-se o papel de NAC1 e BCL6 na regulação da transcrição no CAOV, utilizando-se como modelo FOXQ1. Viu-se que NAC1 e BCL6 interagem através do domínio BEN Cterminal de NAC1, formando um complexo que se liga a motivos de ligação a BCL6 localizados na região promotora de FOXQ1 que, conforme se mostrou, possui três desses motivos. Em seguida, mostrou-se que existe uma correlação positiva entre a expressão de NAC1 e BCL6 em linhagens celulares de CAOV e em tumores. Mostrou-se ainda, que NAC1 liga-se ao promotor de BCL6 de forma dependente da proteína BCL6, ativando a sua transcrição. Dessa forma, descreveu-se de forma inédita um mecanismo através do qual um membro da família BTB/POZ interage com BCL6 atenuando a sua autorregulação negativa. Por fim, através de análise de microarranjo de cDNA identificaram-se possíveis novos alvos de regulação do complexo NAC1/BCL6. Na segunda parte deste trabalho, analisaram-se os efeitos da cisplatina na progressão do CAOV. Mostrou-se que, em resposta ao tratamento por cinco dias com cisplatina 10-5M, células da linhagem A2780 apresentaram aumento de migração, resistência e expressão do fenótipo de células-tronco tumorais CD44+CD24-; além da droga induzir uma parada do ciclo celular em fase G2/M. Também se analisou a secreção de TGF-β1 e CXCL2, citocinas envolvidas com a resistência e metástase no câncer, em resposta à cisplatina, à doxorrubicina e ao paclitaxel, em três linhagens de CAOV derivadas de tumores dos tipos seroso (A2780), endometrioide (MDAH-2774) e de células claras (TOV21G). Mostrou-se que, em resposta à cisplatina, apenas, havia o aumento da secreção de TGF-β1 por células TOV21G e de CXCL2 por células A2780 e TOV21G. Em seguida, buscou-se identificar se CXCL2 exógeno seria capaz de induzir a resistência nas células A2780. Esse efeito não foi observado. Contudo, pode ser explicado pela regulação positiva da expressão de CXCR2 induzida pela cisplatina aqui mostrada. Dessa forma, identificaram-se diferentes mecanismos que podem contribuir para a progressão do CAOVCAPE

Molecular epidemiological investigation of Mayaro virus in febrile patients from Goiania City, 2017-2018.

Mayaro virus (MAYV) has historically been associated with sylvatic transmission; however, urban outbreaks have been reported in Brazil, including cases of co-detection with dengue virus (DENV). Therefore, we performed a molecular survey to investigate MAYV circulation and cocirculation with DENV within Goiania, a major city in Central-West Brazil. Among 375 subjects with arbovirus-like symptoms, 259 were positive for DENV and 26 for MAYV. Of these, 17 were coinfected with DENV-2, suggesting co-transmission of the viruses. The most common complaints at the time of inclusion were myalgia, headache, fever, arthralgia, retro-orbital pain, and skin rash. No specific symptoms were associated with MAYV when either detected alone or co-detected with DENV, compared to that when DENV was detected alone. Most MAYV-infected subjects were women with no recent travel history to rural/sylvatic areas. Phylogenetic reconstruction indicated that the MAYV identified in this study is closely related with a lineage observed in Peru, belonging to genotype D. Our results corroborate the growing circulation of MAYV in urban environments in Brazil and reinforce the need to implement laboratory diagnosis in the Unified Health System, considering that the clinical manifestations of Mayaro fever are similar to those of other arboviruses, particularly dengue. Furthermore, most cases occurred in association with DENV-2. Further phylogenetic studies are needed to evaluate MAYV, which has not been widely examined

Molecular mimicry between Zika virus and central nervous system inflammatory demyelinating disorders: the role of NS5 Zika virus epitope and PLP autoantigens

Background Evidence indicates a strong link between Zika virus (ZikV) and neurological complications. Acute myelitis, optic neuritis, polyneuropathy, and encephalomyelitis that mimic inflammatory idiopathic demyelination disorders (IIDD) after ZikV infection have been reported in Brazil. Objective The present study aims to investigate the possible occurrence of molecular mimicry between ZikV antigens and Multiple Sclerosis (MS) autoantigens, the most frequent IIDD of the central nervous system (CNS). Methods A retrospective cohort study with 305 patients admitted due to suspected arbovirus infection in Rio de Janeiro was performed, all subjects were submitted to neurological examination, and a biological sample was collected for serologic and molecular diagnostic. Bioinformatics tools were used to analyze the peptides shared between ZikV antigens and MS autoantigens. Results Of 305 patients, twenty-six were positive for ZikV and 4 presented IDD patterns found in MS cases. Sequence homology comparisons by bioinformatics approach between NS5 ZikV and PLP MS protein revealed a homology of 5/6 consecutive amino acids (CSSVPV/CSAVPV) with 83% identity, deducing a molecular mimicry. Analysis of the 3D structures revealed a similar conformation with alpha helix presentation. Conclusions Molecular mimicry between NS5 Zika virus antigen and PLP MS autoantigens emerge as a possible mechanism for IDD spectrum in genetically susceptible individuals

Input and output files of selection analysis with Datamonkey.

Input and output files of selection analysis with Datamonkey.</p

Sample metadata and sequencing statistics for Duque de Caxias samples.

Sample metadata and sequencing statistics for Duque de Caxias samples.</p

BEAST xml files and outputs generated in this study.

BEAST xml files and outputs generated in this study.</p

Fig 2 -

Symptoms distribution, RT-qPCR Ct values dynamics and their correlation with genome sequencing coverage. (A) Distribution of symptoms exhibited by all CHIKV positive patients in the Duque de Caxias cohort. (B) The time lag between symptoms onset and sample collection dates exhibits correlation with RT-qPCR Ct values. As infection proceeds, viral loads decrease (Cts increase) likely due to immunological response. (C) Negative correlation between RT-qPCR Cts and genome sequencing coverage. Sequences characterized from samples with higher viral load (lower Cts) tend to exhibit higher coverage, although no strong statistical correlation was inferred on a linear model (p = 0.08).</p