Potential of RASSF1A promoter methylation as a biomarker for colorectal cancer: Meta-analysis and TCGA analysis.

The RAS association domain family protein 1A (RASSF1A) is a tumor suppressor in colorectal cancer (CRC), and is often inactived by hypermethylation. Therefore, we evaluated the association between RASSF1A hypermethylation and the risk and prognosis in CRC. We identified literature through searching PubMed and China National Knowledge Infrastructure databases, and then validated and supplemented the meta-analysis with TCGA analysis. Twenty-three studies involving 2886 subjects of CRC were examined. The meta-analysis showed that RASSF1A promoter methylation inferred high CRC risk (odds ratio, 6.53, 95% confidence interval 3.88-11.01, P < .001) and poor overall survival (hazard ratio 2.85, 95% CI 1.88-4.31, P < .001). The TCGA analysis suggested that effect of RASSF1A promotor methylation was affected by tumor localization (colon vs. rectum). RASSF1A promoter methylation was a predictor of high risk (OR 2.38, 95%CI 1.02-5.6, P = .046) and poor disease free survival(HR 2.25, 95%CI 1.27-3.99, P = .006)in colon adenocarcinoma, but the association was statistically insignificant in rectum adenocarcinoma(HR 1.58, 95% CI 0.69-3.59, P = .28). These results suggested RASSF1A hypermethylation is a risk and a potential prognostic biomarker in CRC.

Effect of cold stress on expression of AMPKalpha-PPARalpha pathway and inflammation genes.

Animals are exposed to various environmental stresses every day, including the stress associated with living in cold temperatures. The aim of this study was to investigate the possible mechanisms of interaction between lipid metabolism and inflammation induced by cold stress in the livers of chickens. Fifteen-day-old male chicks were randomly allocated into 12 groups (10 chickens per group). After exposure of the chickens to the cold stress, cholesterol fractionation was used to examine high-density lipoprotein (HDL) and low-density lipoprotein (LDL) concentrations. Aminotransferase activities were examined with the use of the aspartate transaminase (AST) and alanine transaminase (ALT) assay. The AMP-activated protein kinase alpha-proliferator-activated receptor alpha (AMPKalpha-PPARalpha) pathway genes (AMPKalpha1, AMPKalpha2, PPARalpha, carnitine palmitoyltransferaseI [CPTI], acetyl-CoA carboxylase [ACC]) and inflammatory cytokines (prostaglandin E synthase [PGEs], inducible nitric oxide synthase [iNOS], heme oxygenase-1 [HO-1], nuclear factor kappa-light-chain-enhancer of activated B cells [NF-kappaB], cyclooxygenase-2 [COX-2], and TNF-alpha-like factor [LITAF]) were also measured. The results showed that during the response to cold stress, serum LDL and HDL cholesterol concentrations increased. Histopathologic analyses provided evidence that liver tissues were seriously injured in the chickens exposed to the cold stress. Serum aminotransferase activities were also increased in the group of animals exposed to the cold stress. Additionally, the expressions of AMPKalpha-PPARalpha pathway genes and inflammatory cytokine genes were significantly increased in the animals exposed to cold temperatures. These results suggested that increased inflammation was a feature associated with a lipid-metabolism disorder in the livers of chickens exposed to cold stress.