Análise de mutações e caracterização do gene MYLK4 em carcinomas de mama

Dissertação (mestrado)—Universidade de Brasília, Faculdade em Ciências da Saúde, Programa de Pós-Graduação em Ciências da Saúde, 2014.Muitos fatores são caracterizados como desencadeadores do câncer como os fatores genéticos e a desregulação nos processos de sinalização celular. O acúmulo de mutações em células normais está nos fatores genéticos ligados a carcinogênese e a localização dessas mutações no genoma possui um papel fundamental. Até o momento, diversas mutações têm sido descritas em genes importantes relacionados à carcinogênese mamária. Desregulação nos processos de sinalização celular levam por vezes ao amento da proliferação celular característica fundamental para o desenvolvimento do câncer. Genes da família MYLK (Miosin Light Chain Kinase) codificam proteínas do tipo serina/treonina quinase inicialmente identificados como responsáveis pela fosforilação da cadeia leve da miosina. Estudos anteriores identificaram mutações no gene MYLK4 como de grande importância no câncer de mama. Estudos mostram que um aumento da expressão dos genes MYLK1 e MYLK2 estão relacionados com a carcinogênese mamária. Os membros desta família não foram totalmente caracterizados. Este estudo buscou investigar uma possível relação entre o MYLK4 e o câncer de mama. Foi constatado que a frequência de mutações no gene MYLK4 é baixa tanto em linhagens celulares quanto em amostras clínicas de câncer de mama. Ainda, observamos uma superexpressão do gene em linhagens celulares de câncer de mama e uma maior expressão em mama quando comparado com outros tipos de tecidos normais. A análise por imunohistoquímica em amostras clínicas parafinizadas demonstrou uma maior expressão do MYLK4 no tecido tumoral e presença em tecido normal. Analisando sua expressão em um número maior de amostras clínicas tumorais pareadas com sua contra parte normal ou não, não foram observadas alterações significativas na expressão do MYLK4 apenas uma grande variância em sua expressão. Ensaio de superexpressão do MYLK4 em linhagem celular normal demonstrou um aumento na proliferação celular in vitro. Os dados em conjunto apontam para um possível envolvimento do MYLK4 no crescimento celular em tumores que apresentem superexpressão deste gene. _________________________________________________________________________ ABSTRACTMany factors are characterized as causes of cancer such as genetic factors and deregulation of cellular signaling processes. The accumulation of mutations in normal cells is linked to genetic factors in carcinogenesis and the location of these mutations in the genome plays a key role. To date, several mutations have been described in important genes related to mammary carcinogenesis. Disruption in cellular signaling process sometimes leads to increased cell proliferation, critical to the development of cancer. The MYLK (Light Chain Kinase Miosin) gene family encodes proteins of the serine / threonine kinase family originally identified as responsible for the phosphorylation of myosin light chain. Previous studies have identified mutations in the gene MYLK4 to be important in breast cancer. Studies have shown that increased expression of genes MYLK1 and MYLK2 are related to mammary carcinogenesis. Members of this family have not been fully characterized. This study sought to investigate a possible relationship between MYLK4 and breast cancer. It has been found that the frequency of mutations in the gene MYLK4 is low in both cell lines and clinical samples of breast cancer. Also, we observed a gene overexpression in cell lines of breast cancer and increased expression in normal cells of breast cancer when compared with other types of normal tissues. Analysis by immunohistochemistry in paraffin embedded clinical samples showed an increased expression of MYLK4 in tumor tissue and its presence in normal tissue. Analyzing its expression in a larger number of clinical tumor samples paired with its counterpart normal part or not, no significant changes were observed in the expression of MYLK4 just a great variance in their expression. Assay overexpressing MYLK4 normal cell line showed increase on cell proliferation in vitro. This data together suggest a possible involvement of MYLK4 in cell growth in tumors that exhibit overexpression of this gene

SET domain-containing protein 4 (SETD4) is a newly identified cytosolic and nuclear Lysine Methyltransferase involved in breast cancer cell proliferation

Cancer is comprised of a multitude of epigenetic abnormalities, including the global loss and regional gain of DNA methylation as well as alterations in histone methylation. Here, we characterize a new methyltransferase, SET domain-containing protein 4 (SETD4), which is involved in breast carcinogenesis. Quantitative real-time PCR (qPCR) showed elevated expression levels of SETD4 in several breast cancer cell lines. SETD4 overexpression was confirmed by western blot analysis suggesting a correlation between high expression of SETD4 and a lack of the estrogen receptor (ER) in breast cancer. In addition, cell fractionation studies and confocal immunofluorescence revealed the nuclear and non-nuclear localization of this new protein. SETD4 knockdown in breast cancer cell lines significantly suppressed their proliferation and delayed the G1/S cell cycle transition without affecting apoptosis. Furthermore, western blot analysis showed that knockdown of SETD4 decreased cyclin D1 expression, revealing the involvement of SETD4 in cell cycle regulation. These data imply that SETD4 plays a crucial role in breast carcinogenesis and could be a novel molecular target for the development of new strategies for the diagnosis and treatment of breast cancer

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference -1·69 [-9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5-8] vs 6 [5-8] cm H2O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52-23·52]; p<0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75-0·86]; p<0·0001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status

Health-status outcomes with invasive or conservative care in coronary disease

BACKGROUND In the ISCHEMIA trial, an invasive strategy with angiographic assessment and revascularization did not reduce clinical events among patients with stable ischemic heart disease and moderate or severe ischemia. A secondary objective of the trial was to assess angina-related health status among these patients. METHODS We assessed angina-related symptoms, function, and quality of life with the Seattle Angina Questionnaire (SAQ) at randomization, at months 1.5, 3, and 6, and every 6 months thereafter in participants who had been randomly assigned to an invasive treatment strategy (2295 participants) or a conservative strategy (2322). Mixed-effects cumulative probability models within a Bayesian framework were used to estimate differences between the treatment groups. The primary outcome of this health-status analysis was the SAQ summary score (scores range from 0 to 100, with higher scores indicating better health status). All analyses were performed in the overall population and according to baseline angina frequency. RESULTS At baseline, 35% of patients reported having no angina in the previous month. SAQ summary scores increased in both treatment groups, with increases at 3, 12, and 36 months that were 4.1 points (95% credible interval, 3.2 to 5.0), 4.2 points (95% credible interval, 3.3 to 5.1), and 2.9 points (95% credible interval, 2.2 to 3.7) higher with the invasive strategy than with the conservative strategy. Differences were larger among participants who had more frequent angina at baseline (8.5 vs. 0.1 points at 3 months and 5.3 vs. 1.2 points at 36 months among participants with daily or weekly angina as compared with no angina). CONCLUSIONS In the overall trial population with moderate or severe ischemia, which included 35% of participants without angina at baseline, patients randomly assigned to the invasive strategy had greater improvement in angina-related health status than those assigned to the conservative strategy. The modest mean differences favoring the invasive strategy in the overall group reflected minimal differences among asymptomatic patients and larger differences among patients who had had angina at baseline

Initial invasive or conservative strategy for stable coronary disease

BACKGROUND Among patients with stable coronary disease and moderate or severe ischemia, whether clinical outcomes are better in those who receive an invasive intervention plus medical therapy than in those who receive medical therapy alone is uncertain. METHODS We randomly assigned 5179 patients with moderate or severe ischemia to an initial invasive strategy (angiography and revascularization when feasible) and medical therapy or to an initial conservative strategy of medical therapy alone and angiography if medical therapy failed. The primary outcome was a composite of death from cardiovascular causes, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. A key secondary outcome was death from cardiovascular causes or myocardial infarction. RESULTS Over a median of 3.2 years, 318 primary outcome events occurred in the invasive-strategy group and 352 occurred in the conservative-strategy group. At 6 months, the cumulative event rate was 5.3% in the invasive-strategy group and 3.4% in the conservative-strategy group (difference, 1.9 percentage points; 95% confidence interval [CI], 0.8 to 3.0); at 5 years, the cumulative event rate was 16.4% and 18.2%, respectively (difference, 121.8 percentage points; 95% CI, 124.7 to 1.0). Results were similar with respect to the key secondary outcome. The incidence of the primary outcome was sensitive to the definition of myocardial infarction; a secondary analysis yielded more procedural myocardial infarctions of uncertain clinical importance. There were 145 deaths in the invasive-strategy group and 144 deaths in the conservative-strategy group (hazard ratio, 1.05; 95% CI, 0.83 to 1.32). CONCLUSIONS Among patients with stable coronary disease and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of ischemic cardiovascular events or death from any cause over a median of 3.2 years. The trial findings were sensitive to the definition of myocardial infarction that was used