Summary： Abnormal cholesterol metabolism is associated with an elevated risk of developing athero- sclerosis, hypertension, and diabetes etc. Na＋/K＋-ATPase was found to regulate cholesterol synthesis, distribution ...Summary： Abnormal cholesterol metabolism is associated with an elevated risk of developing athero- sclerosis, hypertension, and diabetes etc. Na＋/K＋-ATPase was found to regulate cholesterol synthesis, distribution and trafficking. This study aimed to examine the effect of high-fat diet on cholesterol me- tabolism in rats and the role of Na＋/K＋-ATPase/Src/ERK signaling pathway in the process. Forty male SD rats were evenly divided into high-fat diet group and control group at random. Animals in the former group were fed on high-fat diet for 12 weeks, and those fed on basic diet served as control. Blood lipids, including total cholesterol （TC）, triglyceride （TG）, high density lipoprotein-cholesterol （HDL-C）, and low density lipoprotein-cholesteral （LDL-C） levels, were detected at 3, 6 and 12 weeks. The ratio of cholesterol content in cytoplasm to that in cell membrane was detected in liver tissues. RT-PCR and Western blotting were used to measure the expression of lipid metabolism-associated genes （HMG-CoA reductase and SREBP-2） after 12-week high-fat diet. Na＋/K＋-ATPase/Src/ERK signaling path- way-related components （Na＋/K＋-ATPase ctl, Src-PY418 and pERK1/2） were also measured by West- ern blotting. The results showed that the serum TC, TG, and LDL-C levels were significantly higher in high-fat diet group than those in control group, while the HDL-C level was significantly lower in high-fat diet group at 6 weeks （P〈0.01）. High-fat diet led to an increase in the cholesterol content in the cytoplasm and cell membrane. The ratio of cholesterol content in cytoplasm to that in cell membrane was elevated over time. The expression of HMG-CoA reductase and SREBP-2 was significantly sup- pressed at mRNA and protein levels after 12-week high-fat diet （P〈0.05）. Moreover, high-fat diet pro- moted the expression of Na＋/K＋-ATPase α1 but suppressed the phosphorylation of Src-PY418 and ERK1/2 at 12 weeks （P〈0.05）. It was concluded that high-fat diet regulates cholesterol metabolism, and Na＋/K＋-ATPase signaling pathway is involved in the process possibly by regulating the expression of lipid metabolism-associated proteins HMG-CoA reductase and SREBP-2.展开更多
This study examined whether insulin-stimulated hypoxia-inducible factor 1α(HIF-1α) expression plays a crucial role in promoting the proliferative vitality and invasive capability in human pancreatic cancer cells.PAN...This study examined whether insulin-stimulated hypoxia-inducible factor 1α(HIF-1α) expression plays a crucial role in promoting the proliferative vitality and invasive capability in human pancreatic cancer cells.PANC-1 cells were divided into three groups:Control group,insulin group and insulin+YC-1(a pharmacological inhibitor of HIF-1α) group in terms of different treatments.Cells in the insulin group or insulin+YC-1 group were treated with insulin(0.1,1,10 and 100 nmol/L) alone or combined with 3-(5’-hydroxymethyl-2’-furyl)-1-benzyl indazole(YC-1,0.1,1,10 and 100 μmol/L).HIF-1α mRNA and protein expression in PANC-1 cells was determined by real-time RT-PCR and Western blotting respectively.Cell proliferation and invasion were measured by using growth curve and invasion assay,respectively.Western blot analysis demonstrated that insulin dose-dependently increased the HIF-1α protein expression,and YC-1 could dose-dependently block this effect.However,neither insulin nor YC-1 altered HIF-1α mRNA levels in PANC-1 cells.Moreover,insulin could enhance the proliferation and invasion of PANC-1 cells,while YC-1 could weaken this effect.It was concluded that the malignant proliferation and local invasion of pancreatic cancer cells may be related to high-insulin microenvironment.The tumor biological behavior change resulting from high-insulin microenvironment may be associated with the increased expression of HIF-1α protein.展开更多
基金supported by a grant from the National Natural Science Foundation of China(No.81200637)
文摘Summary： Abnormal cholesterol metabolism is associated with an elevated risk of developing athero- sclerosis, hypertension, and diabetes etc. Na＋/K＋-ATPase was found to regulate cholesterol synthesis, distribution and trafficking. This study aimed to examine the effect of high-fat diet on cholesterol me- tabolism in rats and the role of Na＋/K＋-ATPase/Src/ERK signaling pathway in the process. Forty male SD rats were evenly divided into high-fat diet group and control group at random. Animals in the former group were fed on high-fat diet for 12 weeks, and those fed on basic diet served as control. Blood lipids, including total cholesterol （TC）, triglyceride （TG）, high density lipoprotein-cholesterol （HDL-C）, and low density lipoprotein-cholesteral （LDL-C） levels, were detected at 3, 6 and 12 weeks. The ratio of cholesterol content in cytoplasm to that in cell membrane was detected in liver tissues. RT-PCR and Western blotting were used to measure the expression of lipid metabolism-associated genes （HMG-CoA reductase and SREBP-2） after 12-week high-fat diet. Na＋/K＋-ATPase/Src/ERK signaling path- way-related components （Na＋/K＋-ATPase ctl, Src-PY418 and pERK1/2） were also measured by West- ern blotting. The results showed that the serum TC, TG, and LDL-C levels were significantly higher in high-fat diet group than those in control group, while the HDL-C level was significantly lower in high-fat diet group at 6 weeks （P〈0.01）. High-fat diet led to an increase in the cholesterol content in the cytoplasm and cell membrane. The ratio of cholesterol content in cytoplasm to that in cell membrane was elevated over time. The expression of HMG-CoA reductase and SREBP-2 was significantly sup- pressed at mRNA and protein levels after 12-week high-fat diet （P〈0.05）. Moreover, high-fat diet pro- moted the expression of Na＋/K＋-ATPase α1 but suppressed the phosphorylation of Src-PY418 and ERK1/2 at 12 weeks （P〈0.05）. It was concluded that high-fat diet regulates cholesterol metabolism, and Na＋/K＋-ATPase signaling pathway is involved in the process possibly by regulating the expression of lipid metabolism-associated proteins HMG-CoA reductase and SREBP-2.
基金supported by a grant from the National Natural Sciences Foundation of China (No.30801098)
文摘This study examined whether insulin-stimulated hypoxia-inducible factor 1α(HIF-1α) expression plays a crucial role in promoting the proliferative vitality and invasive capability in human pancreatic cancer cells.PANC-1 cells were divided into three groups:Control group,insulin group and insulin+YC-1(a pharmacological inhibitor of HIF-1α) group in terms of different treatments.Cells in the insulin group or insulin+YC-1 group were treated with insulin(0.1,1,10 and 100 nmol/L) alone or combined with 3-(5’-hydroxymethyl-2’-furyl)-1-benzyl indazole(YC-1,0.1,1,10 and 100 μmol/L).HIF-1α mRNA and protein expression in PANC-1 cells was determined by real-time RT-PCR and Western blotting respectively.Cell proliferation and invasion were measured by using growth curve and invasion assay,respectively.Western blot analysis demonstrated that insulin dose-dependently increased the HIF-1α protein expression,and YC-1 could dose-dependently block this effect.However,neither insulin nor YC-1 altered HIF-1α mRNA levels in PANC-1 cells.Moreover,insulin could enhance the proliferation and invasion of PANC-1 cells,while YC-1 could weaken this effect.It was concluded that the malignant proliferation and local invasion of pancreatic cancer cells may be related to high-insulin microenvironment.The tumor biological behavior change resulting from high-insulin microenvironment may be associated with the increased expression of HIF-1α protein.
