Modulation of Viability, Proliferation, and Stemness by Rosmarinic Acid in Medulloblastoma Cells: Involvement of HDACs and EGFR

Medulloblastoma (MB) is a heterogeneous group of malignant pediatric brain tumors, divided into molecular groups with distinct biological features and prognoses. Currently available therapy often results in poor long-term quality of life for patients, which will be afflicted by neurological, neuropsychiatric, and emotional sequelae. Identifying novel therapeutic agents capable of targeting the tumors without jeopardizing patients' quality of life is imperative. Rosmarinic acid (RA) is a plant-derived compound whose action against a series of diseases including cancer has been investigated, with no side effects reported so far. Previous studies have not examined whether RA has effects in MB. Here, we show RA is cytotoxic against human Daoy (IC50 = 168 μM) and D283 (IC50 = 334 μM) MB cells. Exposure to RA for 48 h reduced histone deacetylase 1 (HDAC1) expression while increasing H3K9 hyperacetylation, reduced epidermal growth factor (EGFR) expression, and inhibited EGFR downstream targets extracellular-regulated kinase (ERK)1/2 and AKT in Daoy cells. These modifications were accompanied by increased expression of CDKN1A/p21, reduced expression of SOX2, and a decrease in proliferative rate. Treatment with RA also reduced cancer stem cell markers expression and neurosphere size. Taken together, our findings indicate that RA can reduce cell proliferation and stemness and induce cell cycle arrest in MB cells. Mechanisms mediating these effects may include targeting HDAC1, EGFR, and ERK signaling, and promoting p21 expression, possibly through an increase in H3K9ac and AKT deactivation. RA should be further investigated as a potential anticancer agent in experimental MB.

Histone Methyltransferases G9a/Ehmt2 and GLP/Ehmt1 Are Associated with Cell Viability and Poorer Prognosis in Neuroblastoma and Ewing Sarcoma

Changes in epigenetic programming have been proposed as being key events in the initiation and progression of childhood cancers. HMT euchromatic histone lysine methyltransferase 2 (G9a, EHMT2), which is encoded by the G9a (Ehmt2) gene, as well as its related protein GLP, which is encoded by the GLP/Ehmt1 gene, participate in epigenetic regulation by contributing to a transcriptionally repressed chromatin state. G9a/GLP activation has been reported in several cancer types. Herein, we evaluated the role of G9a in two solid pediatric tumors: neuroblastoma (NB) and Ewing sarcoma (ES). Our results show that G9a/Ehmt2 and GLP/Ehmt1 expression is higher in tumors with poorer prognosis, including St4 International Neuroblastoma Staging System (INSS) stage, MYCN amplified NB, and metastatic ES. Importantly, higher G9a and GLP levels were associated with shorter patient overall survival (OS) in both NB and ES. Moreover, pharmacological inhibition of G9a/GLP reduced cell viability in NB and ES cells. These findings suggest that G9a and GLP are associated with more aggressive NB and ES tumors and should be further investigated as being epigenetic targets in pediatric solid cancers.

Epidemiological and genomic investigation of chikungunya virus in Rio de Janeiro state, Brazil, between 2015 and 2018

Since 2014, Brazil has experienced an unprecedented epidemic caused by chikungunya virus (CHIKV), with several waves of East-Central-South-African (ECSA) lineage transmission reported across the country. In 2018, Rio de Janeiro state, the third most populous state in Brazil, reported 41% of all chikungunya cases in the country. Here we use evolutionary and epidemiological analysis to estimate the timescale of CHIKV-ECSA-American lineage and its epidemiological patterns in Rio de Janeiro. We show that the CHIKV-ECSA outbreak in Rio de Janeiro derived from two distinct clades introduced from the Northeast region in mid-2015 (clade RJ1, n = 63/67 genomes from Rio de Janeiro) and mid-2017 (clade RJ2, n = 4/67). We detected evidence for positive selection in non-structural proteins linked with viral replication in the RJ1 clade (clade-defining: nsP4-A481D) and the RJ2 clade (nsP1-D531G). Finally, we estimate the CHIKV-ECSA's basic reproduction number (R0) to be between 1.2 to 1.6 and show that its instantaneous reproduction number (Rt) displays a strong seasonal pattern with peaks in transmission coinciding with periods of high Aedes aegypti transmission potential. Our results highlight the need for continued genomic and epidemiological surveillance of CHIKV in Brazil, particularly during periods of high ecological suitability, and show that selective pressures underline the emergence and evolution of the large urban CHIKV-ECSA outbreak in Rio de Janeiro.

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.

Cyanovirin-N binds to select SARS-CoV-2 spike oligosaccharides outside of the receptor binding domain and blocks infection by SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an enveloped positive stranded RNA virus which has caused the recent deadly pandemic called COVID-19. The SARS-CoV-2 virion is coated with a heavily glycosylated Spike glycoprotein which is responsible for attachment and entry into target cells. One, as yet unexploited strategy for preventing SARS-CoV-2 infections, is the targeting of the glycans on Spike. Lectins are carbohydrate-binding proteins produced by plants, algae, and cyanobacteria. Some lectins can neutralize enveloped viruses displaying external glycoproteins, offering an alternative therapeutic approach for the prevention of infection with virulent β-coronaviruses, such as SARS-CoV-2. Here we show that the cyanobacterial lectin cyanovirin-N (CV-N) can selectively target SARS-CoV-2 Spike oligosaccharides and inhibit SARS-CoV-2 infection in vitro and in vivo. CV-N neutralizes Delta and Omicron variants in vitro better than earlier circulating viral variants. CV-N binds selectively to Spike with a Kd as low as 15 nM and a stoichiometry of 2 CV-N: 1 Spike but does not bind to the receptor binding domain (RBD). Further mapping of CV-N binding sites on Spike shows that select high-mannose oligosaccharides in the S1 domain of Spike are targeted by CV-N. CV-N also reduced viral loads in the nares and lungs in vivo to protect hamsters against a lethal viral challenge. In summary, we present an anti-coronavirus agent that works by an unexploited mechanism and prevents infection by a broad range of SARS-CoV-2 strains.

Biochemical and behavioral effects of rosmarinic acid treatment in an animal model of Parkinson's disease induced by MPTP

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. The main therapeutic approach available nowadays relieves motor symptoms but does not prevent or stop neurodegeneration. Rosmarinic acid (RA), an ester of caffeic and 3,4-dihydroxyphenylacetic acids, is obtained from numerous plant species such as Salvia officinalis L. (sage) and Rosmarinus officinalis (rosemary). This compound has a wide spectrum of biological activities, such as antioxidant and anti-inflammatory, and could be an additional therapy for neurodegenerative disorders. Here we evaluated the potential neuroprotective effects of RA treatment in a murine model of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Mice were separated into four groups: CN, Control/saline; RA, Rosmarinic acid/vehicle; MPTP, MPTP/saline; MPTP+RA, MPTP/RA. RA (20 mg/kg, or vehicle) was administered orally by intra-gastric gavage for 14 days, one hour before MPTP or saline injection. MPTP groups received the drug (30 mg/kg, intraperitoneally) once a day for five days (fourth to the eighth day of the experiment). MPTP-treated animals displayed hyperlocomotion behavior, which was significantly prevented by RA treatment. In addition, RA treatment increased dopaminergic signaling in the parkinsonian mice and improved the monoaminergic system in healthy animals. Analysis of alterations in the striatal mRNA expression of dopaminergic system components showed that MAO-A expression was increased in the MPTP+AR group. Overall, this study brings new evidence of the potential neuroprotective properties of RA not only in preventing behavioral features observed in PD, but also by improving neurotransmission in the healthy brain.

Identification and characterisation of SARS-CoV-2 and Human alphaherpesvirus 1 from a productive coinfection in a fatal COVID-19 case

BACKGROUND

During routine Coronavirus disease 2019 (COVID-19) diagnosis, an unusually high viral load was detected by reverse transcription real-time polymerase chain reaction (RT-qPCR) in a nasopharyngeal swab sample collected from a patient with respiratory and neurological symptoms who rapidly succumbed to the disease. Therefore we sought to characterise the infection.

OBJECTIVES

We aimed to determine and characterise the etiological agent responsible for the poor outcome.

METHODS

Classical virological methods, such as plaque assay and plaque reduction neutralisation test combined with amplicon-based sequencing, as well as a viral metagenomic approach, were performed to characterise the etiological agents of the infection.

FINDINGS

Plaque assay revealed two distinct plaque phenotypes, suggesting either the presence of two severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains or a productive coinfection of two different species of virus. Amplicon-based sequencing did not support the presence of any SARS-CoV-2 genetic variants that would explain the high viral load and suggested the presence of a single SARS-CoV-2 strain. Nonetheless, the viral metagenomic analysis revealed that Coronaviridae and Herpesviridae were the predominant virus families within the sample. This finding was confirmed by a plaque reduction neutralisation test and PCR.

MAIN CONCLUSIONS

We characterised a productive coinfection of SARS-CoV-2 and Herpes simplex virus 1 (HSV-1) in a patient with severe symptoms that succumbed to the disease. Although we cannot establish the causal relationship between the coinfection and the severity of the clinical case, this work serves as a warning for future studies focused on the interplay between SARS-CoV-2 and HSV-1 coinfection and COVID-19 severity.

Epidemiological dynamics of SARS-CoV-2 VOC Gamma in Rio de Janeiro, Brazil

The emergence and widespread circulation of severe acute respiratory syndrome coronavirus 2 variants of concern (VOCs) or interest impose an enhanced threat to global public health. In Brazil, one of the countries most severely impacted throughout the pandemic, a complex dynamics involving variants co-circulation and turnover events has been recorded with the emergence and spread of VOC Gamma in Manaus in late 2020. In this context, we present a genomic epidemiology investigation based on samples collected between December 2020 and May 2021 in the second major Brazilian metropolis, Rio de Janeiro. By sequencing 244 novel genomes through all epidemiological weeks in this period, we were able to document the introduction and rapid dissemination of VOC Gamma in the city, driving the rise of the third local epidemic wave. Molecular clock analysis indicates that this variant has circulated locally since the first weeks of 2021 and only 7 weeks were necessary for it to achieve a frequency above 70 per cent, consistent with rates of growth observed in Manaus and other states. Moreover, a Bayesian phylogeographic reconstruction indicates that VOC Gamma spread throughout Brazil between December 2020 and January 2021 and that it was introduced in Rio de Janeiro through at least 13 events coming from nearly all regions of the country. Comparative analysis of reverse transcription-quantitative polymerase chain reaction (RT-qPCR) cycle threshold (Ct) values provides further evidence that VOC Gamma induces higher viral loads (N1 target; mean reduction of Ct: 2.7, 95 per cent confidence interval = ± 0.7). This analysis corroborates the previously proposed mechanistic basis for this variant-enhanced transmissibility and distinguished epidemiological behavior. Our results document the evolution of VOC Gamma and provide independent assessment of scenarios previously studied in Manaus, therefore contributing to the better understanding of the epidemiological dynamics currently being surveyed in other Brazilian regions.

Differential Expression of Human MicroRNAs During Dengue Virus Infection in THP-1 Monocytes

Dengue virus (DENV) is the most widespread arbovirus, responsible for a wide range of clinical manifestations, varying from self-limited illness to severe hemorrhagic fever. Dengue severity is associated with host intense proinflammatory response and monocytes have been considered one of the key cell types involved in the early steps of DENV infection and immunopathogenesis. To better understand cellular mechanisms involved in monocyte infection by DENV, we analyzed the expression levels of 754 human microRNAs in DENV-infected THP-1 cells, a human monocytic cell line. Eleven human microRNAs showed differential expression after DENV infection and gene ontology and enrichment analysis revealed biological processes potentially affected by these molecules. Five downregulated microRNAs were significantly linked to cellular response to stress, four to cell death/apoptosis, two to innate immune responses and one upregulated to vesicle mediated, TGF-β signaling, phosphatidylinositol mediated signaling, lipid metabolism process and blood coagulation.

COVID-19 diagnosis by RT-qPCR in alternative specimens

BACKGROUND

The high demand for adequate material for the gold standard reverse transcription real-time polymerase chain reaction (RT-qPCR)-based diagnosis imposed by the Coronavirus disease 2019 (COVID-19) pandemic, combined with the inherent contamination risks for healthcare workers during nasopharyngeal swab (NP) sample collection and the discomfort it causes patients, brought the need to identify alternative specimens suitable for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

OBJECTIVES

The aim of this work was to compare saliva and gingival fluid swabs to NP swabs as specimens for RT-qPCR-based SARS-CoV-2 diagnosis.

METHODS

We compared gingival fluid swabs (n = 158) and saliva (n = 207) to the rayon-tipped NP swabs obtained from mild-symptomatic and asymptomatic subjects as specimens for RT-qPCR for SARS-CoV-2 detection.

FINDINGS

When compared to NP swabs, gingival fluid swabs had a concordance rate of 15.4% among positive samples, zero among inconclusive, and 100% among negative ones. For saliva samples, the concordance rate was 67.6% among positive samples, 42.9% among inconclusive, and 96.8% among negative ones. However, the concordance rate between saliva and NP swabs was higher (96.9%) within samples with lower cycle threshold (Ct) values (Ct > 10 ≤ 25).

MAIN CONCLUSIONS

Our data suggests that whereas gingival fluid swabs are not substitutes for NP swabs, saliva might be considered whenever NP swabs are not available or recommended.

Clinical and magnetic resonance imaging patterns of extensive Chikungunya virus-associated myelitis

Chikungunya fever is an arbovirus infection transmitted by the same mosquito vector of dengue and Zika virus. Besides high fever, common clinical symptoms include articular pain and general malaise. Neurological involvement is unusual, but some patients may develop peripheral and central nervous system involvement, including meningoencephalitis, myelitis, Guillain-Barré syndrome, and acute disseminated encephalomyelitis. We present three cases of Chikungunya fever complicated with extensive myelitis. The spinal cord magnetic resonance imaging (MRI) pattern is characterized by multiple dotted-like and longitudinal hyperintense lesions, with contrast enhancement, mostly distributed in the peripheral regions of the spinal cord. It seems that these lesions are mostly located in the perivascular spaces (PVS), related or not to virus attack. Involvement of brain PVS can also be demonstrated, as shown in two of the cases described. Considering the MRI pattern, extensive spinal cord lesion should include Chikungunya as a differential diagnosis, especially during an outbreak.

Exome-Wide Search for Genes Associated With Central Nervous System Inflammatory Demyelinating Diseases Following CHIKV Infection: The Tip of the Iceberg

Chikungunya virus (CHIKV) is a re-emergent arbovirus that causes a disease characterized primarily by fever, rash and severe persistent polyarthralgia, although <1% of cases develop severe neurological manifestations such as inflammatory demyelinating diseases (IDD) of the central nervous system (CNS) like acute disseminated encephalomyelitis (ADEM) and extensive transverse myelitis. Genetic factors associated with host response and disease severity are still poorly understood. In this study, we performed whole-exome sequencing (WES) to identify HLA alleles, genes and cellular pathways associated with CNS IDD clinical phenotype outcomes following CHIKV infection. The cohort includes 345 patients of which 160 were confirmed for CHIKV. Six cases presented neurological manifestation mimetizing CNS IDD. WES data analysis was performed for 12 patients, including the CNS IDD cases and 6 CHIKV patients without any neurological manifestation. We identified 29 candidate genes harboring rare, pathogenic, or probably pathogenic variants in all exomes analyzed. HLA alleles were also determined and patients who developed CNS IDD shared a common signature with diseases such as Multiple sclerosis (MS) and Neuromyelitis Optica Spectrum Disorders (NMOSD). When these genes were included in Gene Ontology analyses, pathways associated with CNS IDD syndromes were retrieved, suggesting that CHIKV-induced CNS outcomesmay share a genetic background with other neurological disorders. To our knowledge, this study was the first genome-wide investigation of genetic risk factors for CNS phenotypes in CHIKV infection. Our data suggest that HLA-DRB1 alleles associated with demyelinating diseases may also confer risk of CNS IDD outcomes in patients with CHIKV infection.

NAC1 attenuates BCL6 negative autoregulation and functions as a BCL6 coactivator of FOXQ1 transcription in cancer cells

Background: Nucleus accumbens-associated protein 1 (NAC1) has multifaceted roles in cancer pathogenesis and progression, including the development of drug resistance, promotion of cytokinesis, and maintenance of “stem cell-like” phenotypes. NAC1 is a transcriptional co-regulator belonging to the bric-a-brac tramtrack broad (BTB) family of proteins, although it lacks the characteristic DNA binding motif of the BTB family. The formation of higher-order transcription complexes likely depends on its interaction with other DNA-binding co-factors.

Results: NAC1 interacts with BCL6 via its C-terminal BEN domain and forms a complex that binds the promoter region and activates transcription of the NAC1 target gene, FOXQ1. NAC1 and BCL6 were coordinately upregulated. Our analysis also identified a novel function of NAC1 in attenuating BCL6 auto-downregulation in ovarian cancer. Lastly, we found a significant overlap among NAC1- and BCL6-regulated genes in tumor cells, suggesting that NAC1 and BCL6 coordinately control transcription in cancer.

Conclusions: The results of this study provide a novel mechanistic insight into the oncogenic roles of NAC1 and underline the importance of developing the NAC1/BCL6-targeted cancer therapy.

Methods: Using the Cistrome database and Chromatin Immunoprecipitation (ChIP) analyses, we identified BCL6 as a potential NAC1- interacting molecule. Co-immunoprecipitation (Co-IP), luciferase reporter assay, immunohistochemistry and microarray analysis were performed to analyze the interaction between NAC1 and BCL6 and the mechanisms by which they regulate the downstream genes including FOXQ1.

The cannabinoid agonist WIN-2 affects acquisition but not consolidation of a spatial information in training and retraining processes: Relation with transcriptional regulation of the endocannabinoid system?

The endocannabinoid system is capable of modulating multiple physiological brain functions including learning and memory. Moreover, there is evidence that the processes of acquisition and consolidation have distinct biological basis. We used the cannabinoid agonist WIN 55,212-2 (WIN-2) to investigate whether chronic CB1 activation affects acquisition and consolidation differently by evaluating gene expression in the hippocampus (HIP) and prefrontal cortex (PFC). Swiss mice were treated with WIN-2 (2 mg/kg) and submitted to the Morris water maze to evaluate different aspects of memory. We observed short-term memory impairment in acquisition of the spatial task while consolidation remained unchanged. In the PFC, animals that received WIN-2 prior to the task exhibited increased expression of the 2-AG synthesis enzyme diacylglycerol lipase and decreased levels of the degradation enzyme monoacylglycerol lipase, while mice that were treated after the task for the evaluation of consolidation exhibited the opposite profile. With respect to genes related to AEA metabolism, no correlation between the molecular and behavioral data could be established. In this sense, the cognitive impairment in the acquisition promoted by WIN-2 treatment may be related to a possible increase in the concentration of 2-AG in the PFC. Overall, this study confirms the relevance of the endocannabinoid system in the modulation of cognitive processes. A better understanding of the mechanisms underlying endocannabinoids roles in cognition could provide guidance for the development of treatments to reduce the cognitive deficits caused by drug abuse.

Behavioral, Biochemical and Molecular Characterization of a Parkinson's Disease Mouse Model Using the Neurotoxin 2'-CH3-MPTP: A Novel Approach

The neurotoxin MPTP has long been used to create a mouse model of Parkinson's disease (PD). Indeed, several MPTP analogues have been developed, including 2'-CH₃-MPTP, which was shown to induce nigrostriatal DA neuronal depletion more potently than MPTP. However, no study on behavioral and molecular alterations in response to 2'-CH₃-MPTP has been carried out so far. In the present work, 2'-CH₃-MPTP was administered to mice (2.5, 5.0 and 10 mg/kg per injection, once a day, 5 days) and histological, biochemical, molecular and behavioral alterations were evaluated. We show that, despite a dose-dependent-like pattern observed for nigrostriatal dopaminergic neuronal death and dopamine depletion, dose-specific alterations in dopamine metabolism and in the expression of dopaminergic neurotransmission-associated genes could be related to specific motor deficits elicited by the different doses tested. Interestingly, 2'-CH₃-MPTP leads to increased DAT and MAO-B transcription, which could explain, respectively, its higher potency and the requirement of higher doses of MAO inhibitors to prevent nigrostriatal neuronal death when compared to MPTP. Also, perturbations in dopamine metabolism as well as possible alterations in dopamine bioavailability in the synaptic cleft were also identified and correlated with strength and ambulation deficits in response to specific doses. Overall, the present work brings new evidence supporting the distinct effects of 2'-CH₃-MPTP when compared to its analogue MPTP. Moreover, our data highlight the utmost importance of a precise experimental design, as different administration regimens and doses yield different biochemical, molecular and behavioral alterations, which can be explored to study specific aspects of PD.

Cholinergic and Dopaminergic Alterations in Nigrostriatal Neurons Are Involved in Environmental Enrichment Motor Protection in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, being characterized by dopaminergic neurodegeneration of substantia nigra pars compacta. PD pharmacotherapy has been based on dopamine replacement in the striatum with the dopaminergic precursor 3,4-dihydroxyphenylalanine (L-DOPA) and/or with dopaminergic agonists, alongside anticholinergic drugs in order to mitigate the motor abnormalities. However, these practices neither prevent nor stop the progression of the disease. Environmental enrichment (EE) has effectively prevented several neurodegenerative processes, mainly in preclinical trials. Several studies have demonstrated that EE induces biological changes, bearing on cognitive enhancement, neuroprotection, and on the attenuation of the effects of stress, anxiety, and depression. Herein, we investigated whether EE could prevent the motor, biochemical, and molecular abnormalities in a murine model of PD induced by 1-methyl-4-phenyl-2,3-dihydropyridine (MPTP). Our results show that EE does not prevent the dopaminergic striatal depletion induced by MPTP, despite having averted the MPTP-induced hyperlocomotion. However, it was able to slow down and avoid, respectively, the 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) depletion. Analysis of dopaminergic mRNA alterations in the midbrain showed that D1R expression was increased by MPTP, while the normal expression level of this receptor was restored by EE. As for the cholinergic system, MPTP led to a decrease in the ChAT gene expression while increasing the expression of both AChE and M1R. EE attenuated and prevented-respectively-ChAT and M1R gene expression alterations triggered by MPTP in the midbrain. Overall, our data brings new evidence supporting the neuroprotective potential of EE in PD, focusing on the interaction between dopaminergic and cholinergic systems.

Abstract A80: NAC1 attenuates BCL6 negative autoregulation and functions as a BCL6 coactivator of FOXQ1 transcription in ovarian cancer (OVCA)

Nucleus accumbens-associated protein 1 (NAC1) is a transcriptional co-regulator that lacks the DNA binding domain, thus relying on other co-factors to form higher-order transcription complexes. The present study aimed to elucidate the mechanism by which NAC1 modulates gene expression in OVCA. Nacc1-/- mice were euthanized, and spleens were collected. Promoter sequences were retrieved using Biostrings and BSgenome packages of Bioconductor 2.12. The position frequency matrix of BCL6 motif was obtained from Cistrome. BCL6 binding motifs on targeted promoters were identified by matchPWM, and log-odd scores calculated by PWMscoreStartingAt. For chromatin immunoprecipitation (ChIP), cells were fixed with 1% (w/v) paraformaldehyde prior to cross-linking with DTBP. Anti-BCL6, anti-NAC1 or rabbit IgG isotype were used for IP, and the genes of interest were amplified by qPCR. HEK293T cells were used for co-immunoprecipitaion (co-IP), and proteins were analyzed by Western blot. Luciferase reporter assays were performed in HeLa cells transfected with siNAC1 and/or siBCL6. Immunohistochemistry was done on tissue microarray (TMA) constituted of 51 primary ovarian high-grade serous carcinoma samples (HGSOC), using anti-NAC1 or anti-BCL6 antibodies. For microarray experiments, OVCAR5 cells were transfected with siNAC1 or siBCL6. Two-tailed t-test was used analyze data (means ± SD; p&lt;0.05). BCL6 consensus binding motifs were mapped to the promoters of the NAC1 targeted genes FOXQ1 (positions A -1000, B -800, and C -150). NAC1 binds to BCL6 motifs as proved by ChIP and qPCR assays conducted in HeLa and MCF7 cells (p&lt; 0.01). Reciprocal co-IP experiments done in HEK293T cells co-transfected with BCL6-FLAG and full-length NAC1-V5 indicated that NAC1 interacts with BCL6 via its C-terminal domain (NAC1-C186). Functional NAC1 is required to form putative NAC1/BCL6 transcription complex, and to modulate FOXQ1 expression in HeLa N130 tTA cells (p&lt; 0.001). Luciferase reporter assays run in HeLa cells transfected with siNAC1 and siBCL6 proved that the genes interact and collaborate to regulate FOXQ1 transcriptional activity (p&lt; 0.01). NAC1 and BCL6 transcriptional and protein expressions correlate in OVCA cell lines (R2=0.7025; p=0.0185), and in HGSOC TMA (R2=0.31; p=0.027), respectively. Furthermore, NAC1 modulates the expression of BCL6 as shown in OSE-NAC1 transfected cells (p=0.041), and in OVCAR5- (p=0.016), OVCAR3- (p=0.0089), SKOV3- (p=0.0216), and taxol-resistant SKOV3TR-siRNA-NAC1 (p=0.0002) transfected cells. BCL6 transcript expression was reduced by 50% in the spleen of Nacc-/- mice (p=0.0068). Endogenous NAC1 and BCL6 ChIP on the consensus BCL6 binding sequence within the BCL6 promoter in OVCA cells showed that BCL6 binds to its own promoter, and that NAC1 was enriched in the ChIP. Competition assay performed in NAC1-C186-OVCAR-3 cells revealed that BCL6 expression is modulated by NAC1 (p&lt;0.0001), thus pointing to a direct interaction between NAC1 and BCL6 as a key phenomenon that attenuates BCL6 auto-downregulation by NAC1. Modulation of gene expression was assessed by cDNA microarray in siNAC1 or siBCL6 transfected OVCAR5 cells: 238 and 188 genes were down- whereas 139 and 113 genes were up-regulated by NAC1 and BCL6, respectively, amongst which 54 genes were down- and 25 genes were up-regulated concomitantly. In conclusion, our study establishes a new mechanism for NAC1-driven OVCA, in which it interacts with BCL6 via its C-terminal domain forming a transcription complex that modulates the expression of target genes. We have also described a novel function of NAC1 in attenuating BCL6 autoregulation in OVCA. Finally, we have found a significant overlap among NAC1- and BCL6-regulated, suggesting a transcription collaboration of NAC1 and BCL6 in OVCA cells. CORRESPONDING AUTHORS: RANGEL, LBA; SHIH, IM.

Citation Format: Alice Laschuk Herlinger, Min Gao, Ren-Chin Wu, Tian-Li Wang, Leticia B A Rangel, Ie-Ming Shih. NAC1 attenuates BCL6 negative autoregulation and functions as a BCL6 coactivator of FOXQ1 transcription in ovarian cancer (OVCA). [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A80.

Abstract P6-11-13: In vitro antineoplastic evaluation of rationally designed naphtoquinone-derived drugs in triple-negative breast cancer cell line

Background: Breast cancer (BC) comprises multiple diseases harboring different genetic alterations, which subtypes respond differently to treatment, and are associated to distinct clinical outcomes. Likewise, triple negative breast cancer (TNBCs) are a heterogeneous subgroup of BC, immunophenotypically negative for estrogen and progesterone receptor, and HER2, that account for 10–15% of all invasive BC, affecting mostly African-American and Hispanic pre-menopausal women. Considering that TNBC have poor prognosis, and cannot be effectively treated with current targeted therapies, the discovery of new treatment options is imperative.

Methods: Novel naphtoquinone-derived drugs were rationally designed to act through multiple pathways aiming the avoidance of drug-resistant phenotype acquisition by tumor cells, and were synthesized following high efficiency and low cost method. Drugs antineoplastic efficacy (AE) was accessed in claudin-low TNBC cell line, MDA-MB-231, through the evaluation of cellular metabolic viability (CMV) (MTT method). Drugs structures are protected by patent. Cells were cultured in RPMI media supplemented with 10% (v/v) FBS and antibiotics until subconfluence; then, 1.5×105 cells/well were subcultured for 72h prior to treatment with drugs (10−4, 10−5, 10−6, 10−7, and 10−8 M). After 24h, CMV was assessed. Experiments in which the lineage was treated with cisplatin, doxorubicin or paclitaxel were run in parallel. The mean and standard-deviation of the absorbancies were used to calculate CMV and drugs IC50 (PrismaGraphPad version 5.1).

Findings: We screened the AE of 43 novel naftoquinones-derived drugs in MDA-MB-231 lineage; seven have decreased its CMV by, at least, 50%, as: PIC1 (IC50 1.15×10−4M; CMV decrease of 50%); PIC6 (IC50 4.24×10−5M; CMV decrease of 70%); PIC10 (IC50 5.07×10−5M; CMV decrease of 70%); PIC 20 (IC50 1.38×10−5M; CMV decrease of 90%); PIC21 (IC50 5.00×10−5M; CMV decrease of 70%); S5 (IC50 7.26×10−5M; CMV decrease of 60%); M20 (IC50 7.94×10−5M; CMV decrease of 60%). Their AE was significantly higher than that of cisplatin (IC50 1.56×10−4M; CMV decrease &lt; 10%), doxorubicin (IC50 1.76×10−4M; CMV decrease of 38%), and paclitaxel (IC50 5.05×10−7M; CMV decrease of 20%).

Interpretation: Altogether, our results present potential novel antineoplastic drugs to treat TNBC from a panel of in house rationally designed naftoquinones-derived compounds, developing an innovative and economically viable project.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-11-13.