Regulação da ativação epigenética do gene MMP2 diante da sinalização da fibronectina em linhagens tumorais de mama

Orientadora : Profª Drª Giseli KlassenCo-orientadora : Profª Drª Edneia A. S. R. CavalieriDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Microbiologia, Parasitologia e Patologia. Defesa: Curitiba, 02/12/2014Inclui referênciasÁrea de concentraçãoResumo: O câncer de mama é o tipo de câncer mais frequente entre as mulheres em todo o mundo. A enzima MMP-2 é uma metaloprotease capaz de degradar o colágeno tipo IV, um dos principais constituintes da matriz extracelular (MEC). Sua função é amplamente descrita por atuar no mecanismo de metástases em diversos tipos de câncer. Estudos recentes demonstraram que a linhagem tumoral de mama MCF7 possui o gene MMP2 regulado por metilação do DNA. Além disso, alguns estudos têm demonstrado que a fibronectina, uma importante proteína constituinte da MEC, é capaz de promover a expressão de MMP-2 em linhagens tumorais de mama. Resultados recentes do nosso grupo mostraram que a linhagem tumoral MCF7 quando tratada com fibronectina por 5 horas sofre 30% de desmetilação da região promotora do gene MMP2. Entretanto, observou-se também que tal processo foi transitório, porque houve a remetilação parcial do promotor quando o estímulo foi retirado. Ainda, a fibronectina induziu o aumento de uma marca de histona no promotor de MMP2 que sinaliza para a ativação da transcrição gênica. Diante disso, o objetivo deste trabalho foi dar continuidade a esse estudo, avaliando a regulação epigenética do gene MMP2 em linhagens tumorais de mama após o cultivo com fibronectina em diferentes tempos. Para isso, células da linhagem MCF7 submetidas ao tratamento com fibronectina por 8, 12 e 24 horas, e da linhagem MDA-MB-436 por 24 horas, tiveram seus níveis de expressão de MMP2, metilação do DNA e modificações de histonas do promotor do gene avaliados. Na linhagem MCF7, o tratamento por 8, 12 e 24 horas foi capaz de promover o aumento da expressão de MMP2 em 7, 25 e 9 vezes, respectivamente, comparado com o controle, assim como a redução da metilação do promotor de 90% (controle) para 70%, 40% e 52%, respectivamente. O tratamento por 24h também promoveu o aumento da marca de ativação gênica H3K4me3. Ainda, após 12h de cultivo com fibronectina, a linhagem MCF7 aumentou sua capacidade migratória. A fim de verificar se o efeito observado não era exclusivo da linhagem MCF7, foi incluída no estudo a linhagem MDA-MB-436 que foi submetida ao tratamento por 24h, e apresentou aumento na expressão gênica de MMP2 (4 vezes) e redução da metilação do promotor (de 90% para 22%). Por fim, as células tratadas foram mantidas em cultivo sem a fibronectina para avaliar a estabilidade das modificações. Essas células, chamadas de recultivo, apresentaram uma redução na expressão gênica e aumento na metilação do promotor quando comparadas com as células logo após os tratamentos, confirmando o efeito transitório da fibronectina nos eventos epigenéticos, que já tinha sido observado após 5 horas de tratamento. Esses dados corroboram e complementam os mecanismos observados pelo nosso grupo de pesquisa e contribuem para a compreensão dos mecanismos epigenéticos que regulam a expressão de um importante gene associado às metástases tumorais. Palavras-chave: Câncer de mama, MMP-2, epigenética, metilação do DNA.Abstract: Breast cancer is the most common cancer worldwide among women. The MMP- 2 enzyme is a metalloprotease capable of degrading type IV collagen, a major constituent of the extracellular matrix (ECM). Its function is widely described by acting in the mechanism of metastasis in various cancers. Recent data has shown that the MCF7 breast tumor cell line has the MMP2 gene regulated by DNA methylation. In addition, some studies have shown that fibronectin, an important constituent of the extracellular matrix, is capable of promoting MMP-2 expression in breast tumor cell lines. Recent results from our group showed that fibronectin was able to induce MMP2 expression by a 30% decrease in its promoter methylation in MCF7 tumor cell line. However, it was also noted that this process was transient, because a partial promoter remethylation was observed when the stimulus was removed. Moreover, a histone marker for an open chromatin conformation was significantly increased. Therefore, the aim of this work was to continue evaluating the epigenetic regulation of the MMP2 gene after cultivation of breast tumor cell lines with fibronectin at different times. To this reason, MCF7 cells subjected to treatment with fibronectin for 8, 12 and 24 hours and MDA-MB-436 cells subjected to treatment for 24 hours, were evaluated by the levels of MMP2 expression, gene promoter DNA methylation and histone modifications. In the MCF7 cell line, treatments for 8, 12 and 24 hours were able to promote 7, 9 and 25-fold increase in MMP2 expression, respectively, compared with the mock. In addition, promoter methylation was reduced from 90% (control) to 70%, 40% and 52%, respectively. Treatment for 24h also promoted an increase of the histone open chromatin conformation marker H3K4me3. Moreover, the migratory capacity of MCF7 cells treated for 12h was increased. In order to confirm the fibronectin effect, the MDA-MB-436 cell line was subjected to 24h fibronectin treatment, which showed an increase in MMP2 gene expression (4-fold) and a reduction of promoter methylation (from 90% to 22%). Finally, the treated cells were kept in culture without fibronectin to evaluate the modifications stability. These cells (recultivation) showed a gene expression reduction and promoter methylation increased when compared to the cells after treatments, confirming the fibronectin transient effect observed after the 5h treatment. These data support and complement the mechanisms observed by our research group and contribute to understand the epigenetic mechanisms that regulate the expression of an important gene associated with tumor metastasis. Keywords: Breast cancer, MMP-2, epigenetics, DNA methylation

Atazanavir/ritonavir monotherapy as maintenance strategy in HIV-1 treated subjects with viral suppression: 96-week analysis results of the MODAT study

The 48-week interim analysis of the MODAT study showed that confirmed virologic failure (CVF) was more frequent in patients simplifying to ATV/r monotherapy compared to maintaining ATV/r-based triple therapy. The DSMB recommended stopping study enrollment but continuing follow-up of enrolled patients. We present the 96-week efficacy analysis

Prognostic value of the fibrosis-4 index in human immunodeficiency virus type-1 infected patients initiating antiretroviral therapy with or without hepatitis C virus

Objective: To evaluate the Fibrosis (FIB)-4 index as a predictor of major liver-related events (LRE) and liver-related death (LRD) in human immunodeficiency virus (HIV) type-1 patients initiating combination antiretroviral therapy (cART). Design: Retrospective analysis of a prospective cohort study. Setting: Italian HIV care centers participating to the ICONA Foundation cohort. Participants: Treatment-naive patients enrolled in ICONA were selected who: initiated cART, had hepatitis C virus (HCV) serology results, were HBsAg negative, had an available FIB-4 index at cART start and during follow up. Methods: Cox regression models were used to determine the association of FIB4 with the risk of major LRE (gastrointestinal bleeding, ascites, hepatic encephalopathy, hepato-renal syndrome or hepatocellular carcinoma) or LRD. Results: Three-thousand four-hundred seventy-five patients were enrolled: 73.3% were males, 27.2% HCV seropositive. At baseline (time of cART initiation) their median age was 39 years, had a median CD4+ T cell count of 260 cells/uL, and median HIV RNA 4.9 log copies/mL, 65.9% had a FIB-4 <1.45, 26.4% 1.45–3.25 and 7.7% >3.25. Over a follow up of 18,662 person-years, 41 events were observed: 25 major LRE and 16 LRD (incidence rate, IR, 2.2 per 1,000 PYFU [95% confidence interval, CI 1.6–3.0]). IR was higher in HCV seropositives as compared to negatives (5.9 vs 0.5 per 1,000 PYFU). Higher baseline FIB-4 category as compared to <1.45 (FIB-4 1.45–3.25: HR 3.55, 95% CI 1.09–11.58; FIB-4 >3.25: HR 4.25, 1.21–14.92) and time-updated FIB-4 (FIB-4 1.45–3.25: HR 3.40, 1.02–11.40; FIB-4 >3.25: HR 21.24, 6.75–66.84) were independently predictive of major LRE/LRD, after adjusting for HIV- and HCV-related variables, alcohol consumption and type of cART. Conclusions: The FIB-4 index at cART initiation, and its modification over time are risk factors for major LRE or LRD, independently of infection with HCV and could be used to monitor patients on cART

Switch to maraviroc with darunavir/r, both QD, in patients with suppressed HIV-1 was well tolerated but virologically inferior to standard antiretroviral therapy: 48-Week results of a randomized trial

Objectives Primary study outcome was absence of treatment failure (virological failure, VF, or treatment interruption) per protocol at week 48. Methods Patients on 3-drug ART with stable HIV-1 RNA <50 copies/mL and CCR5-tropic virus were randomized 1:1 to maraviroc with darunavir/ritonavir qd (study arm) or continue current ART (continuation arm).Results In June 2015, 115 patients were evaluable for the primary outcome (56 study, 59 continuation arm). The study was discontinued due to excess of VF in the study arm (7 cases, 12.5%, vs 0 in the continuation arm, p = 0.005). The proportion free of treatment failure was 73.2% in the study and 59.3% in the continuation arm. Two participants in the study and 10 in the continuation arm discontinued therapy due to adverse events (p = 0.030). At VF, no emergent drug resistance was detected. Co-receptor tropism switched to non-R5 in one patient. Patients with VF reported lower adherence and had lower plasma drug levels. Femoral bone mineral density was significantly improved in the study arm. Conclusion Switching to maraviroc with darunavir/ritonavir qd in virologically suppressed patients was associated with improved tolerability but was virologically inferior to 3-drug therap

Long-term data on the efficacy and tolerability of lamivudine plus dolutegravir as a switch strategy in a multi-centre cohort of HIV-1-infected, virologically suppressed patients

BACKGROUND: Results from clinical trials and observational studies suggest that lamivudine plus dolutegravir (3TC+DTG) could be an effective and tolerated option for simplification in human immunodeficiency virus (HIV)-1-positive patients. MATERIALS AND METHODS: This observational study enrolled HIV-1-infected, virologically suppressed patients switching to 3TC+DTG. Kaplan-Meyer survival analysis was performed to evaluate time to virological failure (VF; defined by a single HIV-RNA determination ≥1000 copies/mL or by two consecutive HIV-RNA determinations ≥50 copies/mL) and time to treatment discontinuation (TD; defined as interruption of either 3TC or DTG), Cox regression was performed to assess predictors, and linear mixed model was performed for repeated measures to measure changes in immunological and metabolic parameters. RESULTS: Five hundred and fifty-six patients were eligible for analysis. Their median CD4+ count at baseline was 668 cells/mm3 and median time of virological suppression was 88 months. Estimated probabilities of maintaining virological suppression at 96 and 144 weeks of follow-up were 97.5% [standard deviation (SD) 0.8] and 96.5% (SD 1.0), respectively. Years since HIV diagnosis was the only predictor of VF. In patients with time of virological suppression <88 months, the rate of VF was higher in the presence of the M184V mutation. Estimated probabilities of remaining on 3TC+DTG at 96 and 144 weeks of follow-up were 79.2% (SD 1.9) and 75.2% (SD 2.2), respectively. A significant increase in CD4 cell count (+44 cells/mm3, P=0.015), CD4/CD8 ratio (+0.10, P=0.002) and high-density lipoprotein cholesterol (+5.4 mg/dL, P=0.036) was found at 144 weeks of follow-up; meanwhile, total cholesterol (-9.1 mg/dL, P=0.007) and triglycerides (-2.7, P=0.009) decreased significantly. CONCLUSIONS: These findings confirm the efficacy and tolerability of 3TC+DTG in virologically suppressed patients. Copyright © 2019 Elsevier Ltd. All rights reserved

Switch to raltegravir-based regimens and HIV DNA decrease in patients with suppressed HIV RNA

Raltegravir intensification is associated with an increase in 2-LTR episomal HIV DNA= circles, indicating a persistent low-level replication, in some individuals in ART with suppressed HIV RNA. We aimed at monitoring residual plasma HIV RNA and cellular HIV DNA in virologically suppressed patients switching to a raltegravir-based regimen

Antiretroviral Therapy Optimisation without Genotype Resistance Testing: A Perspective on Treatment History Based Models

BACKGROUND: Although genotypic resistance testing (GRT) is recommended to guide combination antiretroviral therapy (cART), funding and/or facilities to perform GRT may not be available in low to middle income countries. Since treatment history (TH) impacts response to subsequent therapy, we investigated a set of statistical learning models to optimise cART in the absence of GRT information. METHODS AND FINDINGS: The EuResist database was used to extract 8-week and 24-week treatment change episodes (TCE) with GRT and additional clinical, demographic and TH information. Random Forest (RF) classification was used to predict 8- and 24-week success, defined as undetectable HIV-1 RNA, comparing nested models including (i) GRT+TH and (ii) TH without GRT, using multiple cross-validation and area under the receiver operating characteristic curve (AUC). Virological success was achieved in 68.2% and 68.0% of TCE at 8- and 24-weeks (n\u200a=\u200a2,831 and 2,579), respectively. RF (i) and (ii) showed comparable performances, with an average (st.dev.) AUC 0.77 (0.031) vs. 0.757 (0.035) at 8-weeks, 0.834 (0.027) vs. 0.821 (0.025) at 24-weeks. Sensitivity analyses, carried out on a data subset that included antiretroviral regimens commonly used in low to middle income countries, confirmed our findings. Training on subtype B and validation on non-B isolates resulted in a decline of performance for models (i) and (ii). CONCLUSIONS: Treatment history-based RF prediction models are comparable to GRT-based for classification of virological outcome. These results may be relevant for therapy optimisation in areas where availability of GRT is limited. Further investigations are required in order to account for different demographics, subtypes and different therapy switching strategies

Longitudinal analysis of HIV-1 coreceptor tropism by single and triplicate HIV-1 RNA and DNA sequencing in patients undergoing successful first-line antiretroviral therapy

Objectives: Maraviroc has been shown to be effective in patients harbouring CCR5-tropic HIV-1. While this CCR5 antagonist has initially been used in salvage therapy, its excellent safety profile makes it ideal for antiretroviral treatment simplification strategies in patients with suppressed plasma viraemia. The aim of this study was to compare HIV-1 tropism as detected in baseline plasma RNA and peripheral blood mononuclear cell (PBMC) DNA prior to first-line therapy and to analyse tropism evolution while on successful treatment. Methods: HIV-1 tropism was determined using triplicate genotypic testing combined with geno2pheno[coreceptor] analysis at a 10% false positive rate in 42 patients. Paired pre-treatment plasma RNA and PBMC DNA and two subsequent PBMC DNA samples (the first obtained after reaching undetectable plasma HIV-1 RNA and the second after at least 2 years of suppression of plasma viraemia) were evaluated. Results: Coreceptor tropism was completely concordant in paired pre-treatment RNA and DNA, with 26.2% of HIV-1 sequences predicted to be non-CCR5-tropic. During follow-up, coreceptor tropism switches were detected in 4 (9.5%) patients without any preferential direction. Although false positive rate discrepancies within triplicates were common, the rate of discordance of coreceptor tropism assignment among triplicate results in this mostly CCR5-tropic dataset was only 2.1%, questioning the added value of triplicate testing compared with single testing. Conclusions: HIV-1 coreceptor tropism changes during virologically successful first-line treatment are infrequent. HIV-1 DNA analysis may thus support the choice of a CCR5 antagonist in treatment switch strategies; however, maraviroc treatment outcome data are required to confirm this option

Cohort profile: The Observational cohort for the study of DOlutegravir in Antiretroviral Combination REgimens (ODOACRE)

The Observational cohort for the study of DOlutegravir in Antiretroviral Combination REgimens (ODOACRE) cohort was established in Italy in 2016 to evaluate the overall efficacy and tolerability of dolutegravir (DTG)-based antiretroviral (ARV) regimens in clinical practice

Novel sensitive, specific and rapid pharmacogenomic test for the prediction of abacavir hypersensitivity reaction: HLA-B*57:01 detection by real-time PCR.

Aim: International HIV treatment guidelines recommend HLA-B*57:01 typing before abacavir administration, in order to reduce the incidence of abacavir hypersensitivity reactions, the major cause of early therapy discontinuation. A fast, sensitive and specific test for HLA-B*57:01 detection has been developed in the present study. Materials & methods: Two sets of sequence-specific primers were designed, and amplification rapidly detected by real-time PCR. Results: A total of 108 samples were analyzed in a single-blind fashion, and 41 samples were identified as positive. Complete agreement, with k = 1 (standard error = 0.0962, p < 0.0001), was found, with a validated methodology used in the EPI109367 clinical trial funded by GlaxoSmithKline, and consisting of low-resolution sequence-specific oligonucleotide PCR, followed by high-resolution sequence-specific oligonucleotide PCR carried out on the HLA-B*57-positive samples. Conclusion: We provided a detailed characterization of a novel HLA-B*57:01 screening test, which can be easily implemented by those laboratories already involved in the detection of viral load and virus genotyping