ABSTRACT
Background Arsenic is a human carcinogen. Arsenic and its metabolites affect the expression of p53, but whether there are any changes of p53 phosphorylation and ubiquitination levels in human bronchial epithelium cells (BEAS-2B) are not clear after exposure to arsenic and its metabolites. Objective To study the effects of arsenic and its metabolites monomethylarsic acid (MMA) and dimethylarsinic acid (DMA) on the expression of tumor suppressor gene p53 in BEAS-2B cells. Methods Different concentrations of sodium arsenite (NaAsO2) were used to infect BEAS-2B cells, and the cell viability was detected with CCK-8 reagent to determine the dose and time of NaAsO2 used for the following study. Based on the results of cell viability, the cells were divided into two panels: a sodium arsenide panel and an arsenic methylation metabolite penal. The doses of sodium arsenite were 0, 2, 4, and 6 μmol·L−1 NaAsO2; the arsenic methylation metabolite panel consisted of 0 μmol·L−1 NaAsO2 group (control), 6 μmol· L−1 MMA group, 6 μmol· L−1 DMA group， and 6 μmol· L−1 NaAsO2 group. The cells were collected after 48 h treatment, and the total protein and total RNA were extracted. The relative levels of p53 mRNA expression were determined by quantitative real-time polymerase chain reaction (qRT-PCR), the relative expression levels of p53 protein, p53 Ser9 and Ser15 phosphorylated proteins were determined by Western blot, and the level of p53 ubiquitination was detected by co-immunoprecipitation (CO-IP). Results Compared with the control group, the cell viability rates in all BEAS-2B cells treated by NaAsO2 were significantly reduced (P<0.05), and the 50% cell viability was observed at 6 μmol·L−1. Compared with the control group, the relative expression level of p53 mRNA gradually decreased after NaAsO2 (2, 4, 6 μmol·L−1) treatment (P<0.05), the relative expression levels of p53 protein and Ser9 phosphorylated protein induced by NaAsO2 also decreased gradually (P<0.05), and the relative expression level of p53 Ser15 phosphorylated protein induced by NaAsO2 followed the same pattern, but it was only lower than that of the control group in the 6 μmol·L−1 NaAsO2 group (P<0.05). Compared with the control group, there were no significant effects on the relative expression levels of p53 mRNA, p53 protein, Ser9 and Ser15 phosphorylated proteins in the MMA group and the DMA group. Compared with the control group, the expression level of p53 ubiquitination was significantly decreased and the expression of K48 ubiquitination decreased significantly after NaAsO2 infection. Conclusion Arsenic causes a decrease in the expression of the p53 protein in BEAS-2B cells, largely due to inhibition of the phosphorylated pathway and a decrease in mRNA expression, and protein changes caused by a decrease in p53 ubiquitination do not play a dominant role. MMA and DMA do not affect p53 gene expression.
ABSTRACT
Objective To evaluate the changes of myocardial mechanics before and after percutaneous coronary intervention ( PCI ) in patients with acute myocardial infarction ( AM I ) by ultrasonic speckle tracking technique ,and investigate the recovery of left ventricular myocardium mechanics and the effects of common complications on the improvement of myocardial mechanics . Methods Sixty‐two patients with AM I were examined by echocardiography within 12 hours ,1 week and 3 months after PCI . According to the complications the patients were divided into simple AM I group ( 21 cases ) ,AM I with diabetes mellitus group ( 21 cases) ,and AM I with hypertension group ( 20 cases) . T hirty healthy volunteers were selected as control group . Conventional echocardiographic parameters and left ventricular strain parameters were evaluated in all subjects . Results ①Left ventricular end‐diastolic diameter ( LVEDD) ,left ventricular end‐systolic diameter ( LVESD) ,left ventricular end‐diastolic volume ( LVEDV ) ,and left ventricular end‐systolic volume ( LVESV ) in each AM I group before PCI were greater than the control group ( P ＜ 0 .05 ) ,left ventricular ejection fraction ( LVEF ) , global longitudinal and circumferential endocardial ( midcardial , epicardial) strain ,and left ventricular global radial strain were smaller than the control group ( P ＜0 .05) ;the global longitudinal and circumferential endocardial ( midcardial ,epicardial ) strain ,and left ventricular global radial strain in AM I with diabetes group were less than simple AM I group and AM I with hypertension group ( P ＜0 .05) ; the global longitudinal endocardial strain in AM I with hypertension group was less than simple AM I group ( P ＜0 .05) . ② The LVESV in the third month after PCI was less than that before and during 1 week after surgery ( P ＜ 0 .05 ) ,still greater than control group ( P ＜ 0 .05 ) . LVEF ,the left ventricular global longitudinal and circumferential endocardial( midcardial ,epicardial) strain , and left ventricular global radial strain were greater than those before and during 1 week after surgery ( P＜0 .05) ,still less than control group ( P＜0 .05) ; T here was no significant difference before PCI and during 1 week after PCI about routine and strain parameters ( P＞0 .05 ) . ③ T he degree of improvement of global longitudinal and circumferential endocardial strain in AM I with diabetes group were less than those in simple AM I group( P ＜0 .05) . T he degree of improvement of global longitudinal endocardial strain in AM I with hypertension group was less than that in simple AM I group ( P ＜0 .05) . Conclusions Patients with AMI have poor myocardial mechanics before PCI ,especially those with diabetes mellitus ; myocardial mechanics improves significantly 3 months after PCI ; diabetes mellitus or hypertension affectes the improvement of myocardial mechanics in patients with AM I after PCI .