protocatechuic acids protects against high glucose induced insulin resistance in human visceral adipose tissue

Adipocytes exposed to high glucose concentrations exhibit impaired insulin signaling. Binding of insulin to its membrane receptor activates insulin metabolic pathway leading to IRS-1 and AKT phosphorylations. The accumulation of visceral adipose tissue (VAT) correlates with insulin resistance and metabolic syndrome. Anthocyanins (ACN) are bioactive food compounds of great nutritional interest. We have shown that protocatechuic acid (PCA), a major metabolite of ACN, might exert insulin-sensitizer activities in human visceral adipose tissue. The aim of this work was to define the protective role of PCA against insulin-resistance induced by high glucose in VAT.Methodology: VAT obtained from control subject (BMI≤25) were separated in four experimental groups: i) PCA: samples treated for 24 h with 100 μM PCA, ii) GLU: VAT treated with 30 mM glucose for 24 h, iii) PCA+GLU: 1 hour incubation with 100 μM PCA before adding glucose (30 mM, 24 h), iv) CTR: vehicle. After treatment, VAT groups were (or not) acutely stimulated with insulin (20 nM, 20 min). Tyr-IRS-1 and Ser-Akt phosphorylations were assessed by Western blotting (WB) in basal or insulin stimulated tissues in all experimental groups. Samples were assessed for IRS-1, IR, Akt and GLUT4 protein content by WB. Results: No differences in protein contents between experimental groups were found. GLU tissues showed a lower increment in insulin-stimulated phosphorylation of IRS-1 and Akt compared to CTR and PCA samples. This impaired activation was completely reversed by the pretreatment with PCA.Conclusion: An in-vitro insulin-resistance condition induced by high glucose was established in biopsies of VAT. PCA restores the ability of GLU-tissues to fully respond to insulin by increasing IRS-1 and Akt phosphorylations. These results confirm the insulin-sensitizer effect of PCA on VAT previously reported by our group. An anthocyanin rich diet might help to protect against insulin-resistance in VAT

Circulating pre-treatment Epstein-Barr virus DNA as prognostic factor in locally-advanced nasopharyngeal cancer in a nonendemic area

The prognostic value of pre-treatment Epstein-Barr Virus (EBV) DNA viral load for non-endemic, locally-advanced, EBV-related nasopharyngeal cancer (NPC) patients is yet to be defined. All patients with EBV encoded RNA (EBER)-positive NPC treated at our Institution from 2005 to 2014 with chemotherapy (CT) concurrent with radiation (RT) +/- induction chemotherapy (ICT) were retrospectively reviewed. Pre-treatment baseline plasma EBV DNA (b-EBV DNA) viral load was detected and quantified by PCR. Median b-EBV DNA value was correlated to potential influencing factors by univariate analysis. Significant variables were then extrapolated and included in a multivariate linear regression model. The same variables, including b-EBV DNA, were correlated with Disease Free Survival (DFS) and Overall Survival (OS) by univariate and multivariate analysis. A total of 130 locally-advanced EBER positive NPC patients were evaluated. Overall, b-EBV DNA was detected in 103 patients (79.2%). Median viral load was 554 copies/mL (range 50-151075), and was positively correlated with T stage (p= 0.002), N3a-b vs N0-1-2 stage (p= 0.048), type of treatment (ICT followed by CTRT, p= 0.006) and locoregional and/or distant disease recurrence (p= 0.034). In the overall population, DFS and OS were significantly longer in patients with pre-treatment negative EBV DNA than in positive subjects at the multivariate analysis. Negative b-EBV DNA can be considered as prognostic biomarker of longer DFS and OS in NPC in non-endemic areas. This finding needs confirmation in larger prospective series, with standardized and inter-laboratory harmonized method of plasma EBV DNA quantificatio

Effect of protocatechuic acid on insulin responsiveness and inflammation in visceral adipose tissue from obese individuals: possible role for PTP1B

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Protocatechuic acids protects against high glucose- induced insulin resistance in human visceral adipose tissue

Adipocytes exposed to high glucose concentrations exhibit impaired insulin signaling. Binding of insulin to its membrane receptor activates insulin metabolic pathway leading to IRS-1 and AKT phosphorylations. The accumulation of visceral adipose tissue (VAT) correlates with insulin resistance and metabolic syndrome. Anthocyanins (ACN) are bioactive food compounds of great nutritional interest. We have shown that protocatechuic acid (PCA), a major metabolite of ACN, might exert insulin-sensitizer activities in human visceral adipose tissue. The aim of this work was to define the protective role of PCA against insulin-resistance induced by high glucose in VAT.Methodology: VAT obtained from control subject (BMI≤25) were separated in four experimental groups: i) PCA: samples treated for 24 h with 100 μM PCA, ii) GLU: VAT treated with 30 mM glucose for 24 h, iii) PCA+GLU: 1 hour incubation with 100 μM PCA before adding glucose (30 mM, 24 h), iv) CTR: vehicle. After treatment, VAT groups were (or not) acutely stimulated with insulin (20 nM, 20 min). Tyr-IRS-1 and Ser-Akt phosphorylations were assessed by Western blotting (WB) in basal or insulin stimulated tissues in all experimental groups. Samples were assessed for IRS-1, IR, Akt and GLUT4 protein content by WB. Results: No differences in protein contents between experimental groups were found. GLU tissues showed a lower increment in insulin-stimulated phosphorylation of IRS-1 and Akt compared to CTR and PCA samples. This impaired activation was completely reversed by the pretreatment with PCA.Conclusion: An in-vitro insulin-resistance condition induced by high glucose was established in biopsies of VAT. PCA restores the ability of GLU-tissues to fully respond to insulin by increasing IRS-1 and Akt phosphorylations. These results confirm the insulin-sensitizer effect of PCA on VAT previously reported by our group. An anthocyanin rich diet might help to protect against insulin-resistance in VAT

Linear regression analysis between ω3-/ω6-PUFA ratio, Body Mass Index (BMI) and pSTAT3 decrease.

<p>Correlation between the ω3-/ω6-PUFA ratio and the percentage of pSTAT3 decrease after DHA treatment in control subjects (n=10) (<b>A</b>) and cancer subjects (n=14) (<b>B</b>). Correlation between the BMI and the percentage of pSTAT3 decrease after DHA treatment in control subjects (<b>C</b>) and cancer subjects (<b>D</b>).</p

Linear regression analysis between ω3-/ω6-PUFA ratio and Body Mass Index (BMI).

<p><b>A</b>: all subjects; <b>B</b>: subjects without colorectal cancer; <b>C</b>: subjects affected by colorectal cancer.</p

Immunoblotting analysis of pSTAT3, and evaluation of IL-6 secretion after DHA treatment.

<div><p><b>A</b>: Human visceral adipocytes, collected from the four groups of subjects, were serum-starved for 18 h. Whole cell extracts were separated by SDS-PAGE and analyzed using anti-pSTAT3 antibody. Results were normalized to STAT3 protein content. The data are expressed as means ± SEM. Representative blots are shown. <b>B</b>: IL-6 release was evaluated in the culture media by Elisa as described in Materials and Methods.</p> <p>Data are expressed as means ± SEM. *, P<u><</u>0.05 with respect to the untreated paired cells. NW: normal weight subjects (n=5); Ob: overweight/obese subjects (n=5); NWCC: normal weight with colorectal cancer (n=7); ObCC: overweight/obese with colorectal cancer (n=7).</p></div

Immunoblotting analysis of PPARγ, and adiponectin after DHA treatment.

<p>Human visceral adipocytes, collected from the four groups of subjects, were serum-starved for 18 h and incubated with 10µM DHA, as described in Material and Methods. Nuclear protein extracts and whole cell extracts were separated by SDS-PAGE and analyzed using anti-PPARγ (<b>A</b>) and anti-adiponectin (<b>B</b>) antibodies. Results were normalized to Lamin B and GAPDH protein content, respectively. NW: normal weight subjects (n=5); Ob: overweight/obese subjects (n=5); NWCC: normal weight with colorectal cancer (n=7); ObCC: overweight/obese with colorectal cancer (n=7). The data are expressed as means ± SEM. *, P<u><</u>0.05; **, P<u><</u>0.01; ***, P<u><</u>0.01 compared with untreated paired cells. Representative blots are shown.</p