RESUMO
Although aberrant DNA methylation has been implicated in the pathophysiology of lung cancer, the role of methylation in multidrug resistance (MDR) of lung cancer has remained unclear. To investigate whether certain distinct DNA methylation pattern is associated with acquired MDR of lung adenocarcinoma, methylated-DNA immunoprecipitation-chromatin immunoprecipitation (MeDIP-ChIP) was utilised to compare the genome-wide promoter methylation of the human lung adenocarcinoma MDR A549/cisplatin (A549/DDP) cells with its progenitor A549 cells. The comparison identified 3617 genes with differentially methylated promoter, of which 1581 were hypermethylated and 2036 were hypomethylated. Then, bisulphite sequencing polymerase chain reaction (PCR) (BSP) and quantitative reverse transcription (RT)-PCR (Q-PCR) were used to validate the promoter methylation of five candidate genes and to determine whether the expression of genes was associated with the promoter methylation. BSP confirmed that the promoter methylation incidence of the hypermethylated genes, G protein-coupled receptor 56 isoform 3 (GPR56), metallothionein 1G (MT1G), and RAS association domain family gene 1 (RASSF1), was significantly higher in A549/DDP cells compared with A549 cells (p<0.001, p=0.0099, and p=0.0165), whereas no significant difference was found in that of the other two genes, CCNL2 and BAD (p=0.0594 and p=0.5546). Additionally, Q-PCR showed that the mRNA expression of the three hypermethylated genes was significantly lower in A549/DDP cells compared with A549 cells (all p<0.001). In conclusion, this study reported for the first time that a distinct promoter methylation pattern is associated with MDR of lung adenocarcinoma A549/DDP cells and suggested that GPR56, MT1G, and RASSF1 might be the potential methylation markers associated with acquired MDR of lung adenocarcinoma.
Assuntos
Adenocarcinoma/genética , Metilação de DNA/genética , Resistência a Múltiplos Medicamentos/genética , Resistencia a Medicamentos Antineoplásicos/genética , Neoplasias Pulmonares/genética , Regiões Promotoras Genéticas , Adenocarcinoma de Pulmão , Linhagem Celular Tumoral , Estudo de Associação Genômica Ampla , Humanos , Metalotioneína/genética , Receptores Acoplados a Proteínas G/genética , Proteínas Supressoras de Tumor/genéticaRESUMO
OBJECTIVE: To investigate the changes of the markers of pulmonary vascular endothelial cells (PVECs) after acute lung injury (ALI) induced by bone marrow extract (BME) injection in rabbits. METHODS: Thirty-one rabbits were randomized into control (CG, n=10) and experimental groups (EG, n=21). The rabbits in EG were injected with homogeneous bone marrow extract (0.35 ml/kg, 2 ml/h) at a slow and continuous rate through the jugular vein to establish the model of ALI. At 6 h after the injection, the number of circulating endothelial cells (CECs) in the blood, contents of granule membrane protein-140 (GMP-140), angiotensin converting enzyme (ACE) and endothelin-1 (ET-1) in the plasma and the content of GMP-140 in the pulmonary tissue were determined at various time intervals. Then the animals were killed and routine pathological examination and electron microscopy were performed to observe the changes in the pulmonary tissue. RESULTS: The levels of plasma GMP-140, ACE, ET-1 and CECs were significantly increased in the early stage (0.5 h) and remained higher for 6 h. The marked increase of plasma GMP-140 (3.25 times) in the early stage was negatively correlated to PaO(2), but positively to other parameters. IHC-staining showed that the GMP-140 on the surface of PVECs became weak. CONCLUSIONS: BME injection at slow and continuous rate can establish an acceptable model of ALI. Determination of plasma GMP-140 might be an important measure for the early surveillance and the evaluation of prognosis of ALI in clinical management of serious traffic accidents.