Análise diferencial de genes em linhagens de células de leucemia

O câncer manifesta-se a partir de uma transmutação genética, ou seja, uma modificação no DNA que passa a transmitir informações erradas para o desenvolvimento de suas atividades, ocorrendo assim em genes especiais nomeados como proto-oncogenes. A leucemia é um dos cânceres mais conhecidos e acometem os glóbulos brancos que perdem suas funções e passam a se multiplicar descontroladamente. No entanto a terapia gênica, ainda experimental, busca substituir o gene defeituoso, pelo gene normal. O uso terapêutico de inibidores da tirosino quinase (mesilato de imatinibe), reduz significativamente a progressão da doença e elimina os principais sintomas da fase crônica da leucemia, aumentando assim a expectativa de vida. Os objetivos deste trabalho são analisar a expressão diferencial que estão relacionadas ao desenvolvimento da leucemia mediante a sua evolução ou tratamento usando Imatinibe. Os estudos foram realizados em linhagens celulares submetidos por análises de microarranjos de amostras de Leucemia Mielóide Aguda Bialélica e Leucemia Mielóide Crônica. Foram utilizadas microarranjos da Affymetrix Gene Chip HU133 de células de Leucemia Mieloide extraídos do banco de dados Gene Expression Omnibus. Dentre os resultados obtidos o gene FCAR atua no sistema imune de pacientes com Leucemia, ele é um receptor da glicoproteína transmembrana presente, genes dessa família são usados em imunoterapia usando células T, diferencialmente expresso e está atuando na ativação do sistema imunológico no tratamento da Leucemia Mielóide Aguda. Com isso é possível utilizar as ferramentas de análise de expressão gênica como meio para localizar genes diferencialmente expressos e assim determinar novas terapias gênicas.

Liver Expression of Sulphotransferase 2A1 Enzyme Is Impaired in Patients with Primary Sclerosing Cholangitis: Lack of the Response to Enhanced Expression of PXR

Background/Aim. Sulphotransferase 2A1 (SULT2A1) exerts hepatoprotective effects. Transcription ofSULT2A1gene is induced by pregnane-X-receptor (PXR) and can be repressed by miR-378a-5p. We studied the PXR/SULT2A1 axis in chronic cholestatic conditions: primary sclerosing cholangitis (PSC) and primary biliary cirrhosis (PBC).Materials/Methods. Western-blot/PCRs for SULT2A1/PXR were performed in PSC (n=11), PBC (n=19), and control liver tissues (n=19).PXRandSULT2A1mRNA was analyzed in intestinal tissues from 22 PSC patients. Genomic DNA was isolated from blood of PSC patients (n=120) and an equal number of healthy volunteers. Liver miRNA expression was evaluated using Affymetrix-Gene-Chip miRNA4.0.Results. Increased PXR protein was observed in both PSC and PBC compared to controls and was accompanied by a significant increase of SULT2A1 in PBC but not in PSC. Decreased expression ofSULT2A1mRNA was also seen in ileum of patients with PSC. Unlike PBC, miRNA analysis in PSC has shown a substantial increase in liver miR-378a-5p.Conclusions.PSC is characterized by disease-specific impairment of SULT2A1 expression following PXR activation, a phenomenon which is not noted in PBC, and may account for the impaired hepatoprotection in PSC. miRNA analysis suggests that SULT2A1 expression in PSC may be regulated by miR-378a-5p, connoting its pathogenic role.

Time Dependent Gene Expression Changes in the Liver of Mice Treated with Benzene

Benzene is used as a general purpose solvent. Benzene metabolism starts from phenol and ends with p-benzoquinone and o-benzoquinone. Liver injury inducted by benzene still remains a toxicologic problem. Tumor related genes and immune responsive genes have been studied in patients suffering from benzene exposure. However, gene expression profiles and pathways related to its hepatotoxicity are not known. This study reports the results obtained in the liver of BALB/C mice (SLC, Inc., Japan) administered 0.05 ml/100 g body weight of 2% benzene for six days. Serum, ALT, AST and ALP were determined using automated analyzer (Fuji., Japan). Histopathological observations were made to support gene expression data. c-DNA microarray analyses were performed using Affymetrix Gene-chip system. After six days of benzene exposure, twenty five genes were down regulated whereas nineteen genes were up-regulated. These gene expression changes were found to be related to pathways of biotransformation, detoxification, apoptosis, oxidative stress and cell cycle. It has been shown for the first time that genes corresponding to circadian rhythms are affected by benzene. Results suggest that gene expression profile might serve as potential biomarkers of hepatotoxicity during benzene exposure.