ABSTRACT
Nasopharyngeal carcinoma is a common malignant tumor in southern China, and its occurrence and development mechanism are still not fully understood. However, a large number of studies have shown that DNA methylation has important clinical application value in the screening, diagnosis, treatment and prognosis evaluation of nasopharyngeal carcinoma. DNA methylation affects the division cycle, growth, invasion and migration of nasopharyngeal carcinoma cells by regulating the transcription and protein expression levels of genes associated with tumorigenesis and development. In addition, there are significant differences in DNA methylation expression levels in different stages of nasopharyngeal carcinoma, which provides theoretical guidance and clinical reference for the early diagnosis, timely treatment and response evaluation of nasopharyngeal carcinoma. Current studies have shown that DNA methylation detection may provide a simple and efficient early screening method for nasopharyngeal carcinoma, and can also explore new ideas for the development of non-invasive screening methods.
ABSTRACT
Objective To evaluate the effects of N-acetycysteine on the expression of caveolin-3 (Cav-3) during myocardial ischemia-reperfusion (I/R) in diabetic rats.Methods Twenty-four pathogenfree healthy adult male Sprague-Dawley rats,weighing 230-270 g,were divided into 3 groups (n =8 each) using a random number table:myocardial I/R group (group I/R),diabetes mellitus plus myocardial I/R group (group D) and N-acetycysteine group (group NAC).Diabetes mellitus was induced by injection of streptozotocin 60 mg/kg via the tail vein and confirmed by blood glucose ≥ 16.7 mmol/L 3 days later.At 1 week after successful establishment of the model,N-acetycysteine 1.5 g · kg-1 · d-1 was injected through a gastric tube into stomach for 4 consecutive weeks in group NAC,and the equal volume of normal saline was given for 4 consecutive weeks in I/R and D groups.Myocardial I/R was then induced by 30 min ligation of the left anterior descending branch of the coronary artery followed by 2 h of reperfusion.At the end of reperfusion,the myocardial infarct size was determined by triphenyl tetrazolium chloride staining,the levels of serum creatine kinase-MB (CK-MB) and 15-F2t-Isoprostane were measured by enzyme-linked immunosorbent assay,and the expression of myocardial Cav-3,Akt,phosphor-Akt (p-Akt),endothelial nitric oxide synthase (eNOS) and phosphor-eNOS (p-eNOS) was detected by Western blot.Results Compared with group I/R,the myocardial infarct size and levels of serum CK-MB and 15-F2t-Isoprostane were significantly increased,and the myocardial Cav-3,p-Akt and p-eNOS expression and NO level were decreased in group D (P＜0.05).Compared with group D,the myocardial infarct size and levels of serum CK-MB and 15-F2t-Isoprostane were significantly decreased,and the myocardial Car-3,p-Akt and p-eNOS expression and NO level were increased in group NAC (P＜0.05).Conclusion N-acetycystein can activate Akt/eNOS/NO signaling pathway through up-regulating myocardial Cav-3 expression,thus reducing myocardial I/R injury in diabetic rats.