DNA methylation occurs in the displacement loop (D-loop) region of mammals; however, D-loop regions of certain tumor tissue types were found to be de‑methylated. Whether hypomethylation of the D‑loop region is involved in the regulation of the mitochondrial DNA (mtDNA) copy number and nicotinamide adenine dinucleotide subunit 2 (ND‑2) expressions in colorectal cancer has remained elusive. In the present study, the association between methylation status of the D‑loop region, mtDNA copy number and ND‑2 expression was investigated in 65 colorectal cancer specimens and their corresponding non‑cancerous tissues. In addition, a de‑methylation experiment was performed on the Caco‑2 colorectal cancer cell line by using 5‑aza-2'-deoxycytidine (5‑Aza). The methylation rate of the D‑loop region in all 65 colorectal cancer tissues was markedly reduced when compared with that of their corresponding non‑cancerous tissues (13.8 vs. 81.5%; P<0.05). Furthermore, the methylation rate of the D‑loop region in colorectal cancer tissues was markedly decreased in clinicopathological stages III and IV compared with that in clinicopathological stages I and II (7.1 and 0% vs. 25 and 16%; P<0.05). In addition, the mean relative mtDNA copy number and ND‑2 expression in colorectal cancer tissues were increased compared with those in the corresponding non‑cancerous tissues. De‑methylation of the D‑loop region was associated with an elevated mtDNA copy number and an increased ND‑2 expression. Furthermore, the mtDNA copy number and ND‑2 expression in Caco‑2 cells were significantly increased after 5‑Aza treatment. In conclusion, de‑methylation of the D‑loop region is likely to be involved in the regulation of the mtDNA copy number and ND-2 expression.

Celecoxib could ameliorate hepatic fibrosis and cirrhosis in TAA-rat model through suppression of the mesenchymal biomarkers in the hepatocytes while restoring the levels of their epithelial biomarkers. The inhibitory effect of celecoxib on the EMT of hepatocytes is associated with reduction of intrahepatic inflammation, preservation of normal basement matrix, and inhibition of TGF-β1/Smad pathway.

Betaine has previously been demonstrated to protect the liver against alcohol-induced fat accumulation. However, the mechanism through which betaine affects alcohol-induced hepatic lipid metabolic disorders has not been extensively studied. The present study aimed to investigate the effect of betaine on alcoholic simple fatty liver and hepatic lipid metabolism disorders. A total of 36 rats were randomly divided into control, ethanol and ethanol + betaine groups. Liver function, morphological alterations, lipid content and tumor necrosis factor (TNF)-α levels were determined. Hepatic expression levels of diacylglycerol acyltransferase (DGAT) 1, DGAT2, sterol regulatory element binding protein (SREBP)-1c, SREBP-2, fatty acid synthase (FAS), 3-hydroxy-3-methyl-glutaryl (HMG)-CoA reductase, peroxisome proliferator-activated receptor λ coactivator (PGC)-1α, adiponectin receptor (AdipoR) 1 and AdipoR2 were quantified. Serum and adipose tissue adiponectin levels were assessed using an enzyme-linked immunoassay. The results demonstrated that alcohol-induced ultramicrostructural alterations in hepatocytes, including the presence of lipid droplets and swollen mitochondria, were attenuated by betaine. Hepatic triglyceride, free fatty acid, total cholesterol and cholesterol ester contents and the expression of DGAT1, DGAT2, SREBP-1c, SREBP-2, FAS and HMG-CoA reductase were increased following ethanol consumption, however were maintained at control levels following betaine supplementation. Alcohol-induced decreases in hepatic PGC-1α mRNA levels and serum and adipose tissue adiponectin concentrations were prevented by betaine. The downregulation of hepatic AdipoR1 which resulted from alcohol exposure was partially attenuated by betaine. No significant differences in liver function, TNF-α, phospholipid and AdipoR2 levels were observed among the control, ethanol and ethanol + betaine groups. Overall, these results indicated that betaine attenuated the alcoholic simple fatty liver by improving hepatic lipid metabolism via suppression of DGAT1, DGAT2, SREBP-1c, FAS, SREBP-2 and HMG-CoA reductase and upregulation of PGC-1α.

BackgroundIncreased intra-hepatic resistance to portal blood flow is the primary factor leading to portal hypertension in cirrhosis. Up-regulated expression of cyclooxygenase-2 (COX-2) in the cirrhotic liver might be a potential target to ameliorate portal hypertension.ObjectiveTo verify the effect of celecoxib, a selective inhibitor of COX-2, on portal hypertension and the mechanisms behind it.MethodsCirrhotic liver model of rat was established by peritoneal injection of thiacetamide (TAA). 36 rats were randomly assigned to control, TAA and TAA+celecoxib groups. Portal pressures were measured by introduction of catheters into portal vein. Hepatic fibrosis was assessed by the visible hepatic fibrotic areas and mRNAs for collagen III and α-SMA. The neovasculature was determined by hepatic vascular areas, vascular casts and CD31 expression. Expressions of COX-2, vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2) and related signal molecules were quantitated.ResultsCompared with TAA group, the portal pressure in TAA+celecoxib group was significantly decreased by 17.8%, p<0.01. Celecoxib treatment greatly reduced the tortuous hepatic portal venules. The data of fibrotic areas, CD31expression, mRNA levels of α-SMA and collagen III in TAA+celecoxib group were much lower than those in TAA group, p<0.01. Furthermore, the up-regulation of hepatic mRNA and protein levels of VEGF, VEGFR-2 and COX-2 induced by TAA was significantly inhibited after celecoxib treatment. The expressions of prostaglandin E2 (PGE2), phosphorylated extracellular signal-regulated kinase (p-ERK), hypoxia-inducible factor-1α (HIF-1α), and c-fos were also down-regulated after celecoxib treatment.ConclusionsLong term administration of celecoxib can efficiently ameliorate portal hypertension in TAA rat model by its dual inhibitory effects on the intrahepatic fibrosis and angiogenesis. The anti-angiogenesis effect afforded by celecoxib may attribute to its modulation on VEGF/VEGFR-2 through the down-regulation of integrated signal pathways involving PGE2- HIF-1α- VEGF and p-ERK- c-fos- VEGFR-2.