Prognostic significance of high triglyceride and apolipoprotein B levels in patients with stage III and high-risk stage II colorectal cancer undergoing curative surgery.

Although epidemiologic studies suggest that dyslipidemia increases the risk of colorectal cancer (CRC), the prognostic value of blood lipid and apolipoprotein levels in CRC remains unclear. The aim of the present study was to investigate the impact of blood lipid and apolipoprotein levels on the prognosis of patients with stage III and high-risk stage II CRC undergoing curative surgery. Preoperative levels of total cholesterol, triglycerides (TG), high-density lipoprotein, low-density lipoprotein, very-low-density lipoprotein, apolipoprotein A1 and apolipoprotein B (APO-B) in patients with CRC undergoing surgery were evaluated. The cut-off values of these factors were determined by the maximal x2 method and were used to classify patients into two prognostic groups: Poor and good prognosis groups. The patients prognostic values were assessed using the Kaplan-Meier curve and Cox regression analysis. In addition, the impact of these parameters on the prognosis and their predictive accuracy were evaluated using nomograms and Harrells concordance index, respectively. In total, 246 patients were included in this evaluation. Based on the cut-off points for TG (1.53 mmol/l in men and 1.58 mmol/l in women) and APO-B (0.73 mmol/l in men and women), the present study determined that both TG and APO-B were predictors of disease-free survival (DFS) and overall survival (OS). Multivariate analysis demonstrated that high TG (men, ≥1.53 mmol/l; women, ≥1.58 mmol/l) and high APO-B (≥0.73 mmol/l) levels were significantly associated with decreased DFS and OS. Nomograms that included values for TG and APO-B levels demonstrated higher predictive accuracy compared with that of nomograms without these values. These results indicated that TG and APO-B levels may be good independent prognostic biomarkers after radical CRC surgery. Therefore, adjusting these parameters to moderate levels may be beneficial.

The effect of n-3/n-6 polyunsaturated fatty acids on acute reflux esophagitis in rats.

BACKGROUND: Polyunsaturated fatty acids (PUFAs) play various roles in inflammation. However, the effect of PUFAs in the development of reflux esophagitis (RE) is unclear. This study is to investigate the potential effect of n-3/n-6 PUFAs on acute RE in rats along with the underlying protective mechanisms. METHODS: Forty Sprague Dawley rats were randomly divided into four groups (n = 10 in each group). RE model was established by pyloric clip and section ligation. Fish oil- and soybean oil-based fatty emulsion (n-3 and n-6 groups), or normal saline (control and sham operation groups) was injected intraperitoneally 2 h prior to surgery and 24 h postoperatively (2 mL/kg, respectively). The expressions of interleukin (IL)-1ß, IL-8, IL-6 and myeloid differentiation primary response gene 88 (MyD88) in esophageal tissues were evaluated by Western blot and immunohistochemistry after 72 h. The malondialdehyde (MDA) and superoxide dismutase (SOD) expression in the esophageal tissues were determined to assess the oxidative stress. RESULTS: The mildest macroscopic/microscopic esophagitis was found in the n-3 group (P < 0.05). The expression of IL-1ß, IL-8, IL-6 and MyD88 were increased in all RE groups, while the lowest and highest expression were found in n-3 and n-6 group, respectively (P < 0.05). The MDA levels were increased in all groups (P < 0.05), in an ascending trend from n-3, n-6 groups to control group. The lowest and highest SOD levels were found in the control and n-3 group, respectively (P < 0.05). CONCLUSION: n-3 PUFAs may reduce acute RE in rats, which may be due to inhibition of the MyD88-NF-kB pathway and limit oxidative damage.

Decreased n-6/n-3 polyunsaturated fatty acid ratio reduces chronic reflux esophagitis in rats.

AIM: To investigate the effect of dietary ratio of n-6/n-3 PUFAs on chronic reflux esophagitis (RE) and lipid peroxidation. METHOD: Rat RE model were established and then fed on a diet contained different n-6/n-3 PUFA ratios (1:1.5, 5:1, 10:1) or received pure n-6 PUFA diet for 14 days. Esophageal pathological changes were evaluated using macroscopic examination and hematoxyline-eosin staining. IL-1ß, IL-8, and TNFα mRNA and protein levels of were determined using RT-PCR and Western blotting, respectively. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were determined using ELISA. RESULTS: The severity of esophagitis was lowest in the PUFA(1:1.5) group (P<0.05). IL-1ß, IL-8, and TNFα mRNA and protein and MDA levels were significantly increased in model groups with the increasing n-6/n-3 PUFA ratios. SOD levels were significantly decreased in all RE PUFA groups (P<0.05). CONCLUSION: Esophageal injury and lipid peroxidation appeared to be ameliorated by increased n-3 PUFAs intake.

Role of ERp46 in ß-cell lipoapoptosis through endoplasmic reticulum stress pathway as well as the protective effect of exendin-4.

Endoplasmic reticulum (ER) stress is considered as a key factor in free fatty acid (FFA)-induced apoptosis. ERp46, a new member of the thioredoxin family, is highly expressed in pancreatic ß-cells and plays an important role in glucose toxicity. In this study we examined the potential role of ERp46 in palmitic acid (PA)-induced cell apoptosis and the protective role of exendin-4, a long-acting agonist of the hormone glucagon-like peptide-1 (GLP-1) receptor. The glucose-sensitive mouse ß-pancreatic cell line, ßTC6, was used to investigate the mechanisms of PA-induced apoptosis. Our results showed that ERp46 expression was reduced in a dose- and time-dependent manner after PA treatment. Furthermore, inhibition of ERp46 expression by small interfering (si)RNA-mediated silencing enhanced the ER stress response via three separate pathways and increased ßTC6 cell apoptosis rates. Moreover, exendin-4 reduced the ER stress response and levels of apoptosis in NC transfected cells after PA treatment, but not in cells transfected with ERp46siRNA. In conclusion, ERp46 plays a protective role in PA-induced cell apoptosis by decreasing the ER stress response and might be a novel target for anti-diabetic drugs. Exendin-4 might protect against ßTC6 cell lipoapoptosis in part by activating ERp46 signaling pathway.

Effect of PANDER in ßTC6-cell lipoapoptosis and the protective role of exendin-4.

Chronic exposure to high concentrations of saturated fatty acids, such as palmitic acid (PA), leads to apoptosis of pancreatic ß-cells through the activation of the c-Jun N-terminal kinase (JNK) signaling pathway. This study of ß-cell lipoapoptosis was designed to investigate the roles of pancreatic-derived factor (PANDER), a pro-apoptosis cytokine-like peptide, and exendin-4, a long-acting agonist of the hormone glucagon-like peptide-1 (GLP-1) receptor and anti-apoptosis factor. The glucose-sensitive mouse ß-pancreatic cell line, ßTC6, was used to investigate the mechanisms of PA-induced apoptosis. Twenty-four hours of PA exposure led to increased PANDER expression in a dose- and time-dependent manner, and significantly increased phosphorylation of JNK. Treatment with the JNK-specific inhibitor SP600125 reduced the PA-induced PANDER expression. After the 24h of PA exposure, cells also underwent marked apoptosis and showed increased activation of the apoptosis protease, caspase-3. The small interfering (si)RNA-mediated silencing of PANDER gene expression significantly reduced both of these effects. When PA-treated ßTC6 cells were exposed to exogenous exendin-4, JNK activation was inhibited, PANDER expression was decreased, and the numbers of apoptotic cells were reduced. Collectively, these results demonstrated that the JNK-mediated signaling mechanism of PA-induced ß-cell apoptosis involves up-regulated expression of PANDER and activation of caspase-3. Exendin-4 may protect against lipoapoptosis by interfering with the JNK-PANDER pathway.

[Role of nuclear factor of kB in tumor necrosis factor alpha-mediated INS-1 cell apoptosis].

OBJECTIVE: To investigate the effect of cytokine tumor necrosis factor alpha(TNFalpha) on pancreatic beta cells apoptosis and the effect of transcription factor nuclear factor of kappa B (NF-kB) on TNFalpha-mediated apoptosis. METHODS: INS-1 cells, a pancreatic beta cell line, were cultured,and recombinant DNA technique, transfection and reinfection technology were used to obtain INS-1/IkBDeltaN cells expressing inhibitor of kB (IkB)alphaDeltaN, mutant IkBalpha (inhibitor of NF-kB). DNA fragmentation assay and fluorescence analysis using a kB-luc reporter gene were applied to observe the NF-kB activity and beta cell apoptosis. RESULTS: NF-kB activity induced by IL-Ibeta was detectable in INS-1 cells but not in INS-1/IkBDeltaN cells. After incubation of the cells with IL-1beta (10 micro g/L), TNFalpha (100 micro g/L) and interferon (IFN)gamma (100 000 U/L) for 48 hours, the combination of TNFalpha and IFNgamma induced apoptosis in INS-1 cells but not in INS-1/IkBDeltaN cells. No apoptosis was observed after incubation of INS-1 cells with IL-1beta or IFNgamma or IL-1beta plus IFNgamma. CONCLUSION: Apoptosis is one of the TNFalpha-induced beta-cell death forms. NF-kB may play an important role in the TNFalpha-mediated beta-cell apoptosis. Inhibition of NF-kB activation protects beta-cells from TNFalpha-induced apoptosis.

[The effect of peroxisome proliferator-activated receptor alpha and gamma ligands on free fatty acid-induced INS-1 cell impairment].

OBJECTIVE: To investigate the effect of peroxisome proliferator-activated receptor alpha and gamma (PPARalpha and PPARgamma) ligands on free fatty acid (FFA)-induced pancreatic beta-cell impairment. METHODS: Insulinoma cell line beta-cell (INS-1 cells) were treated with PPARalpha ligand (clofibrate) and PPARgamma ligands (troglitazone and thiazolidinedione). C, N diphenyl-N'-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) viability assay and DNA fragmentation analysis were used to evaluate the effect of PPARalpha and PPARgamma ligands on FFA-induced INS-1 cell impairment. RESULTS: The viability of INS-1 cells decreased after incubation of the cells with FFA (0.25 - 1 mmol/L) for 24 hours. FFA (1 mmol/L) was also found to induce INS-1 cell apoptosis. Comparison of the cells treated with or without clofibrate (100 micro mol/L), troglitazone (10 micro mol/L) and thiazolidinedione (100 micro mol/L), we found that these PPARalpha and PPARgamma ligands could protect INS-1 cells from the cytotoxicity of FFA, including lipoapoptosis. CONCLUSION: FFA mediates significant lipotoxicity and lipoapoptosis in beta-cells and application of PPARalpha and PPARgamma ligands might be of value in protection of beta-cells from FFA cytotoxicity.