AIM:To investigate the signaling mechanism of antioxidative action by curcumin and its impact on glucose disposal. METHODS:Male C57BL/6J mice were fed with either a normal diet (n = 10) or a high fat diet (HFD) (n = 20) to induce obesity and insulin resistance. After 16 wk, 10 HFD-fed mice were further treated with daily curcumin oral gavage at the dose of 50 mg/kg body weight (BW) (HFD + curcumin group). After 15 d of the curcumin supplementation, an intraperitoneal glucose tolerance test was performed. Fasting blood samples were also collected for insulin and glucose measurements. Insulin-sensitive tissues, including muscle, adipose tissue and the liver, were isolated for the assessments of malondialdehyde (MDA), reactive oxygen species (ROS) and nuclear factor erythroid-2-related factor-2 (Nrf2) signaling. RESULTS:We show here that in a HFD mouse model, short-term curcumin gavage attenuated glucose intolerance without affecting HFD-induced BW gain. Curcumin also attenuated HFD-induced elevations of MDA and ROS in the skeletal muscle, particularly in its mitochondrial fraction, but it had no such an effect in either adipose tissue or the liver of HFD-fed mice. Correspondingly, in skeletal muscle, the levels of total or nuclear content of Nrf2, as well as its downstream target, heme oxygenase-1, were reduced by HFD-feeding. Curcumin intervention dramatically reversed these defects in Nrf2 signaling. Further analysis of the relationship of oxidative stress with glucose level by a regression analysis showed a positive and significant correlation between the area under the curve of a glucose tolerance test with MDA levels either in muscle or muscular mitochondria. CONCLUSION:These findings suggest that the shortterm treatment of curcumin in HFD-fed mice effectively ameliorates muscular oxidative stress by activating Nrf2 function that is a novel mechanism for its effect in improving glucose intolerance. Key words: Oxidative stress; Insulin resistance; Glucose tolerance; Nuclear factor erythroid-2-related factor-2; Curcumin; Mitochondria

Background Centromere Protein F (CENPF) associates with the centromere–kinetochore complex and influences cell proliferation and metastasis in several cancers. The role of CENPF in breast cancer (BC) bone metastasis remains unclear. Methods Using the ONCOMINE database, we compared the expression of CENPF in breast cancer and normal tissues. Findings were confirmed in 60 BC patients through immunohistochemical (IHC) staining. Microarray data from GEO and Kaplan–Meier plots were used analyze the overall survival (OS) and relapse free survival (RFS). Using the GEO databases, we compared the expression of CENPF in primary lesions, lung metastasis lesions and bone metastasis lesions, and validated our findings in BALB/C mouse 4T1 BC models. Based on gene set enrichment analysis (GSEA) and western blot, we predicted the mechanisms by which CENPF regulates BC bone metastasis. Results The ONCOMINE database and immunohistochemical (IHC) showed higher CENPF expression in BC tissue compared to normal tissue. Kaplan–Meier plots also revealed that high CENPF mRNA expression correlated to poor survival and shorter progression-free survival (RFS). From BALB/C mice 4T1 BC models and the GEO database, CENPF was overexpressed in primary lesions, other target organs, and in bone metastasis. Based on gene set enrichment analysis (GSEA) and western blot, we predicted that CENPF regulates the secretion of parathyroid hormone-related peptide (PTHrP) through its ability to activate PI3K–AKT–mTORC1. Conclusion CENPF promotes BC bone metastasis by activating PI3K–AKT–mTORC1 signaling and represents a novel therapeutic target for BC treatment.

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Induction of adipocyte apoptosis has been postulated as a novel strategy with which to treat obesity. The effects of curcumin, a polyphenol compound, on the apoptotic signaling pathway in SW872 adipocytes were investigated in the present study. The results showed that cell viability decreased following curcumin treatment in a time- and dose-dependent manner. The results from a single-stranded DNA ELISA assay indicated that curcumin causes the number of apoptotic cells to increase in a concentration-dependent manner. In addition, curcumin treatment resulted in an increased expression of Bax, and a decrease in that of of Bcl-2, with a concomitant upregulation of the Bax/Bcl-2 ratio. Curcumin treatment also led to the release of cytochrome c from mitochondria into the cytosol. Similarly, caspase-dependent poly (ADP) ribose polymerase (PARP) cleavage by curcumin was observed in the current study. In conclusion the results indicate that curcumin is an effective therapeutic agent with which to induce apoptosis in adipocytes. This effect is, in part, mediated through the mitochondrial pathway, which involves upregulation of the Bax/Bcl-2 ratio, cytochrome c release, activation of caspase-3 and the cleavage of PARP.

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Curcumin is a yellow pigment isolated from Corcuma longan. This research investigates the improvement of curcumin on INS-1 cells with insulin resistance induced by high glucose. INS-1 cells were treated with high glucose (30 mmol L(-1)) for 48 h. Subsequently, the medium was replaced with curcumin for 24 h. Curcumin effectively increased insulin gene expression and glucose stimulated insulin secretion (GSIS) in a dose-dependent manner. Furthermore, the molecular mechanism of curcumin-induced insulin expression and secretion in high glucose-induced INS-1 cells was investigated in this study. Curcumin increased the expression of glucose transporter 2 (GLUT2) and phosphorylation of insulin receptor (IR), insulin receptor substrate-1 (IRS1), phosphatidylinositol-3-kinase (PI3K) and AKT in the INS-1 cells. Moreover, curcumin stimulation increased the expression of PDX-1 and GCK. This investigation suggests that curcumin prevented high glucose-reduced insulin expression and secretion through activation of the PI3K/Akt/GLUT2 pathway in INS-1 cells.

Slug is an E-cadherin repressor and a suppressor of PUMA (p53 upregulated modulator of apoptosis) and it has recently been demonstrated that Slug plays an important role in controlling apoptosis. In this study, we examined whether Slug’s ability to silence expression suppresses the growth of cholangiocarcinoma cells and/or sensitizes cholangiocarcinoma cells to chemotherapeutic agents through induction of apoptosis. We targeted the Slug gene using siRNA (Slug siRNA) via full Slug cDNA plasmid (Slug cDNA) transfection of cholangiocarcinoma cells. Slug siRNA, cisplatin, or Slug siRNA in combination with cisplatin, were used to treat cholangiocarcinoma cells in vitro. Western blot was used to detect the expression of Slug, PUMA, and E-cadherin protein. TUNEL, Annexin V Staining, and cell cycle analysis were used to detect apoptosis. A nude mice subcutaneous xenograft model of QBC939 cells was used to assess the effect of Slug silencing and/or cisplatin on tumor growth. Immunohistochemical staining was used to analyze the expression of Slug and PUMA. TUNEL was used to detect apoptosis in vivo. The results showed that PUMA and E-cadherin expression in cholangiocarcinoma cells is Slug dependent. We demonstrated that Slug silencing and cisplatin both promote apoptosis by upregulation of PUMA, not by upregulation of E-cadherin. Slug silencing significantly sensitized cholangiocarcinoma cells to cisplatin through upregulation of PUMA. Finally, we showed that Slug silencing suppressed the growth of QBC939 xenograft tumors and sensitized the tumor cells to cisplatin through PUMA upregulation and induction of apoptosis. Our findings indicate that Slug is an important modulator of the therapeutic response of cholangiocarcinoma cells and is potentially useful as a sensitizer in cholangiocarcinoma therapy. One of the mechanisms is the regulation of PUMA by Slug.

Background Identification of master regulators (MRs) using transcriptome data in cervical cancer (CC) could help us to develop biomarkers and find novel drug targets to fight this disease. Methods We performed differential expression (DE) analyses of public microarray and RNA-seq transcriptome data of CC and normal cervical tissues (N). Virtual Inference of Protein activity by Enriched Regulon analysis (VIPER) was used to convert the DE outcomes to differential activity (DA) signature for MRs. Synergy analysis was conducted to study synergistic effect of MR-pairs. TCGA and microarray data were used to test the association of expression of a MR and a clinical feature or a molecular feature (e.g. somatic mutations). Various bioinformatic tools/websites (DAVID, GEPIA2, Oncomine, cBioPortal) were used to analyze the expression of the top MRs and their regulons. Results Ten DE and 10 DA signatures were generated for CC. Two MRs, DNA topoisomerase II alpha (TOP2A) and centromere protein F (CENPF) were found to be up-regulated, activated and synergistic in CC compared to N across the 10 datasets. The two MRs activate a common set of genes (regulons) with functions in cell cycle, chromosome, DNA damage etc. Higher expression of CENPF was associated with metastasis. High expression of both MRs is associated with somatic mutation of a set of genes including tumor suppressors (TP53, MSH2, RB1) and genes involved in cancer pathways, cell cycle, DNA damage and repair. The magnitude of up-regulation and the absolute expression level of both MRs in CC are significantly higher compared to many other cancer types. Conclusion TOP2A and CENPF are a synergistic pair of MRs that are overexpressed and activated in CC. Their high expression is correlated with some prognosis features (e.g. metastasis) and molecular features (e.g. somatic mutations) and distinctly high in CC vs. many other cancer types. They may be good biomarkers and anticancer drug targets for CC.