Effects of N-acetylcysteine on the expressions of UCP1 and factors related to thyroid function in visceral adipose tissue of obese adults: a randomized, double-blind clinical trial

BACKGROUND

Evidences have shown that obesity is influenced by various factors, including various hormones such as thyroid hormones and the body's metabolism rate. It seems that practical solutions such as weight loss diets and common drugs can affect these potential disorders. In this study, we investigate one of these common drugs, N-Acetylcysteine (NAC), on expressions of UCP1 and factors related to thyroid function in adults with obesity.

METHODS AND ANALYSIS

The current investigation was carried out as a randomized clinical trial (RCT) including 43 adults with obesity who were potential candidates for bariatric surgery. These individuals were randomly divided into two groups: 600 mg of NAC (n = 22) or placebo (n = 21) for a duration of 8 weeks. Visceral adipose tissue was utilized in the context of bariatric surgery to investigate the gene expression of UCP1 and thyroid function. Polymerase chain reaction (PCR) was performed in duplicate for UCP1, DIO2, DIO3, THRα and β, and 18s RNA (as an internal control) using the provided instructions to investigate the expression of the respective genes.

RESULTS

Our findings revealed that after 8 weeks compared to placebo, NAC caused a significant decrease in the expression of the DIO3 gene as one of the genes related to thyroid function and metabolism. However, regarding other related genes, no statistically significant was found (despite the increase in UCP1, DIO2, and THRα expression and decrease in THRβ expression). In addition, after adjustment of possible confounders, no significant effect was observed on anthropometric factors and serum levels of thyroid hormones.

CONCLUSION

The results of this study indicate that, following an 8-week period, NAC effectively decreases the expression of the DIO3 gene in the visceral fat tissue, in comparison to the placebo.

The Function of the Immune System, Beyond Strategies Based on Cell-Autonomous Mechanisms, Determines Cancer Development: Immune Response and Cancer Development

Although cancer remains a challenging disease to treat, early detection and removal of primary tumors through surgery or chemotherapy/radiotherapy can offer hope for patients. The privilege paradigm in cancer biology suggests that cell-autonomous mechanisms play a central role in tumorigenesis. According to this paradigm, these cellular mechanisms are the primary focus for the prevention and treatment of cancers. However, this point of view does not present a comprehensive theory for the initiation of cancer and an effective therapeutic strategy. Having an incomplete understanding of the etiology of cancer, it is essential to re-examine previous assumptions about carcinogenesis and develop new, practical theories that can account for all available clinical and experimental evidence. This will not only help to gain a better understanding of the disease, but also offer new avenues for treatment. This review provides evidence suggesting a shift in focus from a cell-autonomous mechanism to systemic mechanisms, particularly the immune system, that are involved in cancer formation.

Thyroid Hormones Imbalances and Risk of Colorectal Cancer: a Meta-analysis

PURPOSE

No conclusive information is available about the association between hypothyroidism or hyperthyroidism and risk of colorectal cancer (CRC). We therefore aimed to summarize the findings of observational studies on the relation between hypothyroidism or hyperthyroidism and risk of CRC.

METHODS

A literature search was conducted using relevant keywords in online databases for appropriate publications through July 2023. Random effects model was used to calculate combined effect sizes (ESs) and 95% confidence intervals (CIs) to investigate relationship between hypothyroidism or hyperthyroidism and CRC risk.

RESULTS

Totally, we included 13 studies in the current systematic review and meta-analysis, with a total sample size of 33,557,450 individuals and 25,363 cases of CRC. Pooling 13 effect sizes revealed no significant association between hypothyroidism and risk of CRC (combined effect size: 1.13, 95% CI 0.87-1.48, P = 0.343). There was also no significant association between hyperthyroidism and risk of CRC (combined effect size: 1.09, 95% CI 0.75-1.57, P = 0.638). Additionally, there were significant associations between hypothyroidism and risk of CRC in the Far Eastern studies, between hyperthyroidism and risk of CRC in the Middle East, along with small sample size studies.

CONCLUSIONS

This meta-analysis did not reveal any association between hypothyroidism or hyperthyroidism and risk of CRC.

TRIAL REGISTRATION

PROSPERO CRD42022331089.

The interplay between obesity, immunosenescence, and insulin resistance

Obesity, which is the accumulation of fat in adipose tissue, has adverse impacts on human health. Obesity-related metabolic dysregulation has similarities to the metabolic alterations observed in aging. It has been shown that the adipocytes of obese individuals undergo cellular aging, known as senescence. Senescence can be transmitted to other normal cells through a series of chemical factors referred to as the senescence-associated secretory phenotype (SASP). Most of these factors are pro-inflammatory compounds. The immune system removes these senescent T-cells, but immunosenescence, which is the senescence of immune cells, disrupts the clearance of senescent T-cells. Immunosenescence occurs as a result of aging or indirectly through transmission from senescent tissues. The significant occurrence of senescence in obesity is expected to cause immunosenescence and impairs the immune response to resolve inflammation. The sustained and chronic inflammation disrupts insulin's metabolic actions in metabolic tissues. Therefore, this review focuses on the role of senescent adipocyte cells in obesity-associated immunosenescence and subsequent metabolic dysregulation. Moreover, the article suggests novel therapeutic approaches to improve metabolic syndrome by targeting senescent T-cells or using senotherapeutics.

Effects of N-acetylcysteine on aging cell and obesity complications in obese adults: a randomized, double-blind clinical trial

Background

We decided to conduct this study with the aim of investigating the effects of N-Acetylcysteine (NAC) on obesity complications and senescence of visceral adipose tissue in obese adults.

Methods and analysis

The present study was conducted as a randomized clinical trial (RCT) (Clinical trial registry number: IRCT20220727055563N1) on 40 obese adults candidates for bariatric surgery, who were randomly assigned to receive 600 mg of NAC (n = 20) or placebo as a control (n = 20) for 4 weeks. During bariatric surgery, visceral adipose tissue was used to examine gene expression and senescence cells using SA-β-gal.

Results

Our findings showed that intervention with NAC significantly reduces SA-β-gal activity (as a marker of senescence) and expression of p16 and interleukin 6 (IL-6) genes in the visceral adipose tissue compared to placebo in obese adults for 4 weeks. In addition, our findings showed the potential and beneficial effect of NAC administration on reducing the levels of inflammatory factors including IL-6 and high-sensitivity C-reactive protein (hs-CRP), as well as the level of fasting blood sugar (FBS), homeostatic model assessment of insulin resistance (HOMA-IR), and insulin compared to placebo after adjusting for confounders. No significant effect was indicated on anthropometric factors and lipid profile.

Conclusion

Findings showed that NAC, in addition to having a potential beneficial effect on reducing some of the complications caused by obesity, seems to have synolytic/senomorphic potential as well.

Clinical trial registration

[https://clinicaltrials.gov/], identifier [IRCT20220727055563N1].

Isoproterenol Alters Metabolism, Promotes Survival and Migration in 5-Fluorouracil-Treated SW480 Cells with and without Beta-hydroxybutyrate

People with cancer often experience long-term physical and psychological stress, which can have a significant impact on tumor metabolism and treatment. The effects of adrenergic signaling on metabolic pathways are well known, but only a few studies have looked into the connection between this signaling and tumor metabolism. This study examined the effects of treatment with isoproterenol (Iso) alone and in combination with β-hydroxybutyrate (βHB), a mitochondrial fuel, on the metabolism, survival, and migration of SW480 colon cancer cells treated with 5-fluorouracil (5FU). The researchers measured the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) to determine the metabolic profile of these cells. They also analyzed the gene expression of PGC-1α, c-MYC, and NANOG to investigate the relationship between metabolic phenotype and stemness status. Scratch assays were used to assess cell migration. The results showed that Iso treatment increased cell viability in both SW480 and 5FU-treated SW480 cells. There was a significant decrease in ECAR and an increase in OCR after Iso treatment in both cell types. The expression of c-MYC and NANOG, genes associated with stemness, increased, while the expression of PGC-1α, a gene related to oxidative phosphorylation, decreased following Iso treatment. Iso treatment also increased the migration potential of both SW480 and 5FU-treated SW480 cells. These findings suggest that under stressful conditions, 5FU-treated colon cancer cells can utilize the oxidative phosphorylation pathway for growth and migration.

Alterations of DNA methylation and expression of genes related to thyroid hormone metabolism in colon epithelium of obese patients

Background

Colorectal cancer is common among obese individuals. The purpose of the current study was to determine changes in DNA methylation status and mRNA expression of thyroid hormone receptor beta (THRB), as a tumor suppressor, and thyroid hormone inactivating enzyme, type 3 deiodinase (DIO3) genes, in human epithelial colon tissues of healthy obese individuals.

Methods

Colon biopsies were analyzed by methylation sensitive-high resolution melting (MS-HRM) to investigate promoter methylation of DIO3 and THRB, and by quantitative real-time polymerase chain reaction to assay expression of DIO3 and THRB mRNA on eighteen obese and twenty-one normal-weight healthy men.

Results

There was no significant difference in mean methylation levels at the THRB promoter region between the two groups. Nevertheless, obesity decreased THRB expression levels, significantly (P < 0.05; fold change: 0.19). Furthermore, obesity attenuated DNA methylation (P < 0.001) and enhanced mRNA expression of DIO3 (P < 0.05; fold change: 3).

Conclusions

Our findings suggest that obesity may alter expression of THRB and DIO3 genes through epigenetic mechanism. Alterations of THRB and DIO3 expressions may predispose colon epithelium of obese patients to neoplastic transformation.

The Effects of Ovalbumin on Proliferation, Migration, and Stemness Properties of Chemoresistant SW480 Colon Cancer Cells

Egg peptides are factors in the embryonic environment with many significant biological activities, such as anticancer activity. Therefore, the current study investigates the effect of egg ovalbumin (OVA) on survival, cell cycle, self-renewal ability, stemness properties, and migration in SW480 colon cancer cells and 5-fluorouracil (5FU) resistant subgroup. MTT test was performed to assess cell viability. Flow cytometry was employed to analyze the cell cycle. Clonogenic assay and spheroid formation were used to assess the effect of OVA on self-renewal and stemness properties. Wound healing assay and RT-PCR were performed to analyze migration and gene mRNA expression. We demonstrated that OVA (8 and 12 mg/ml) attenuated cell viability, induced cell-cycle arrest, inhibited colony formation, and non-significantly reduced spheroid formation and migration in both cell lines. Furthermore, OVA downregulated the expression of Nanog, c-Myc, and NDRG1 in both cells, suggesting a stemness and self-renewal attenuation by OVA. In conclusion, OVA exposure inhibited the 5FU-SW480 chemo-resistant subpopulation growth by inducing cell cycle arrest and diminishing self-renewal and partially stemness properties of colon cancer cells.

Selective thyroid hormone receptor beta agonist, GC-1, is capable to reduce growth of colorectal tumor in syngeneic mouse models

OBJECTIVE

The effect of thyroid hormone (TH) on cancers was proposed more than 100 years ago; however, conclusions are conflicting. THs are precisely regulated at tissue and cellular levels. It seems that this regulation is altered in cancers. Thyroid hormone receptor beta (TRβ) has anti-proliferative and tumor-suppressive effects in many cancer cells. Therefore, we decided to investigate thyroid hormone receptor beta (THRB) expression and activation by the selective agonist, GC-1, on tumor growth in a syngeneic mouse model of colorectal cancer (CRC) and colon cell lines.

METHODS

In vitro cell viability assay using MTT analysis, cell cycle analysis by PI staining, and FACS analysis were performed. In vivo tumor growth measurements were carried out by caliper and [¹⁸F] Fluoro-2-deoxy-2-D-glucose (FDG) - PET imaging. Gene expressions were determined using quantitative-PCR.

RESULTS

Some concentrations of GC-1 had a marked negative effect on the cell viability of colorectal cell lines. Cell cycle analysis showed that the anti-proliferative effect of GC-1 may not result from cell cycle arrest or apoptosis. Tumor growth analysis in mice harboring colorectal tumor showed that GC-1 treatment for 8 d profoundly inhibited tumor growth and ¹⁸FDG uptake. THRB expression was decreased in mice tumor; however, it was upregulated following GC-1 administration.

CONCLUSIONS

Our results showed that specific activation of TRβ by GC-1 had negative effect on tumor growth and restored its gene expression in tumors of CRC mice model.

Association between IGF-1 levels ranges and all-cause mortality: A meta-analysis

The association between IGF‐1 levels and mortality in humans is complex with low levels being associated with both low and high mortality. The present meta‐analysis investigates this complex relationship between IGF‐1 and all‐cause mortality in prospective cohort studies. A systematic literature search was conducted in PubMed/MEDLINE, Scopus, and Cochrane Library up to September 2019. Published studies were eligible for the meta‐analysis if they had a prospective cohort design, a hazard ratio (HR) and 95% confidence interval (CI) for two or more categories of IGF‐1 and were conducted among adults. A random‐effects model with a restricted maximum likelihood heterogeneity variance estimator was used to find combined HRs for all‐cause mortality. Nineteen studies involving 30,876 participants were included. Meta‐analysis of the 19 eligible studies showed that with respect to the low IGF‐1 category, higher IGF‐1 was not associated with increased risk of all‐cause mortality (HR = 0.84, 95% CI = 0.68–1.05). Dose–response analysis revealed a U‐shaped relation between IGF‐1 and mortality HR. Pooled results comparing low vs. middle IGF‐1 showed a significant increase of all‐cause mortality (HR = 1.33, 95% CI = 1.14–1.57), as well as comparing high vs. middle IGF‐1 categories (HR = 1.23, 95% CI = 1.06–1.44). Finally, we provide data on the association between IGF‐1 levels and the intake of proteins, carbohydrates, certain vitamins/minerals, and specific foods. Both high and low levels of IGF‐1 increase mortality risk, with a specific 120–160 ng/ml range being associated with the lowest mortality. These findings can explain the apparent controversy related to the association between IGF‐1 levels and mortality.

Chronic gastrointestinal bleeding caused by a Dieulafoy's lesion in the small intestine: a case report

Introduction

Dieulafoy’s lesion, first found by Paul Georges Dieulafoy, is an infrequent but important cause of recurrent upper gastrointestinal bleeding. The bleeding is usually severe, but patients rarely present with chronic, occult gastrointestinal bleeding.

Case presentation

In this article, we discuss the case of a 68-year-old caucasian man with a history of recurrent hematemesis and chronic anemia with evidence of extravasation of contrast in the lumen of the bowel loop on computed tomography angiography. The patient was taken to the operating room, and a laparotomy procedure was performed.

Conclusion

Due to the infrequency of Dieulafoy’s lesion compared with other causes of gastrointestinal bleeding, it is often missed in the process of differential diagnosis. In this article, we have demonstrated the importance of this disease and different approaches to the treatment of this lesion, considering the location of the lesion among other factors.

Colorectal cancer causes alteration of thyroid hormone profile in newly diagnosed patients

OBJECTIVES

Subcellular alteration of thyroid hormones (THs) signaling is proposed in many types of cancers. Some studies show deiodinase type 3, as an oncofetal protein, re-expresses in some cancer types. Therefore, we aimed to investigate the product of this enzyme, reverse triiodothyronine (rT3) in serum of newly diagnosed colorectal cancer (CRC) patients.

METHODS

In this cross-sectional study, blood from 38 laboratory-confirmed cases was taken, and serum levels of rT3, total T3 (triiodothyronine), total T4 (thyroxine), free T3, free T4, and thyroid-stimulating hormone (TSH) were detected by using an enzyme-linked immunosorbent assay.

RESULTS

The results illustrated that rT3 and free T3 levels increased in patients with early stages of colorectal cancer, despite normal levels of total T3, total T4, free T4, and TSH.

CONCLUSION

The elevation of rT3 in CRC patients can probably be due to the re-expression of deiodinase type 3 in CRC. Further research is needed to study the role of intracellular THs modulation in CRC and its impact on CRC treatment.

Association of alpha-1-antitrypsin deficiency with vitamin D status: who is most at risk of getting severe COVID-19?

Introduction

Coronavirus disease 2019 (COVID-19), a new disease that we do not know yet how to treat, is rapidly evolving and has forced us to stay indoors. Surprisingly, a broad range of symptoms has been reported since COVID-19 emergence. Individual variations in susceptibility to SARS-CoV-2 can be due to non-genetic and genetic factors. Alpha-1-antitrypsin deficiency (AATD) is an inherited condition that is associated with an increased risk of liver and lung diseases which may increase susceptibility to COVID-19 infection. At the same time, there could be a possibility of developing non-hereditary AATD.

Discussion

In addition to some evidence showing the role of vitamin D deficiency in COVID-19 pathology, it has been recognized that there is a biological link between AAT and vitamin D. Therefore, here we offer a new perspective that lower vitamin D levels in COVID-19 patients can cause acquired AATD that provide a condition with more disease severity and a higher risk of death. As a consequence, COVID-19 individuals with vitamin D deficiency may have a higher risk of morbidity and mortality.

Conclusion

Therefore, early vitamin D and AAT assessments and optimal interventions could be helpful to prevent severe COVID-19 outcomes.

Effects of vitamin D supplementation on depression and some involved neurotransmitters

BACKGROUND

Low vitamin D levels are associated with a dysregulated hypothalamic-pituitary-adrenal (HPA) axis and depression but a causal relationship has not been established. This study aimed to evaluate the effects of vitamin D supplementation on depression severity, serum 25(OH)D, and some neurotransmitters in patients with mild to moderate depression.

METHODS

An 8-week double-blind randomized clinical trial was conducted on 56 subjects with mild to moderate depression, aged 43.0 ± 1.15yrs. The patients were randomly allocated into two groups: intervention (50,000 IU cholecalciferol/2wks) and control (placebo). Biochemical parameters (serum 25(OH)D, iPTH, oxytocin and platelet serotonin), and depression severity (Beck Depression Inventory-II (BDI-II¹)) were initially and finally assessed.

RESULTS

Following intervention, significant changes were observed in the intervention group compared to the controls: 25(OH)D concentrations increased (+40.83±28.57 vs. +5.14±23.44 nmol/L, P<0.001) and BDI scores decreased (-11.75±6.40 vs. -3.61±10.40, P = 0.003). Oxytocin concentrations were significantly reduced in controls (-6.49±13.69 ng/mL, P = 0.01), but between -group differences were insignificant. Within- and between-group differences of platelet serotonin concentrations were not significant; however, the increment in controls was higher (+0.86±10.82 vs. +0.26±9.38 ng/mL, P = 0.83).

LIMITATIONS

Study duration may not reflect the long-term effects of vitamin D on depression. It seems necessary to assess tryptophan-hydroxylasetypes1&2 in relation to vitamin D in serotonin pathways.

CONCLUSIONS

Eight-week supplementation with 50,000 IU/2wks vitamin D, elevated 25(OH)D concentration of subjects with mild to moderate depression and significantly improved their depression severity. However, there was no evidence that the anti-depressive effect of vitamin D supplementation is mediated by the measured neurotransmitters.

Fasting Insulin and Risk of Cancer Related Mortality in Non-diabetic Adults: A Dose-response Meta-analysis of Cohort Studies

BACKGROUND

Insulin is known to have direct and indirect effects on cell cycle progression, proliferation and metastatic activities. We performed a dose-response meta-analysis to investigate the association between hyperinsulinemia and all-cause cancer related mortality.

METHODS

A systematic literature search was conducted on MEDLINE and SCOPUS databases to include all published articles up to January 2019. Combined hazard ratios (HRs) with 95% Confidence Intervals (CIs) were estimated using DerSimonian and Laird random-effects models. A dose-response analysis was also conducted to further explore insulin's relationship with cancer-related mortality.

RESULTS

We identified seven studies, with a total of 23,990 participants, who reported the association between hyperinsulinemia and cancer-related mortality. Results from the eligible studies indicated that higher fasting insulin levels were not associated with an increased risk of cancer mortality (pooled HR: 1.14, 95% CI: 0.99-1.32), however, significant heterogeneity was present (I2 = 60.3%, P heterogeneity = 0.001). A subgroup analysis based on gender demonstrated a significant association between fasting insulin level and cancer mortality in men (pooled HR: 1.92, 95% CI: 1.23-3.01, P heterogeneity = 0.281).

CONCLUSION

This dose-response meta-analysis showed a direct significant association between fasting insulin level and cancer mortality in men.

New Insight into Diabetes Management: From Glycemic Index to Dietary Insulin Index

BACKGROUND

Despite efforts to control hyperglycemia, diabetes management is still challenging. This may be due to focusing on reducing hyperglycemia and neglecting the importance of hyperinsulinemia; while insulin resistance and resultant hyperinsulinemia preceded diabetes onset and may contribute to disease pathogenesis.

OBJECTIVE

The present narrative review attempts to provide a new insight into the management of diabetes by exploring different aspects of glycemic index and dietary insulin index.

RESULTS

The current data available on this topic is limited and heterogeneous. Conventional diet therapy for diabetes management is based on reducing postprandial glycemia through carbohydrate counting, choosing foods with low-glycemic index and low-glycemic load. Since these indicators are only reliant on the carbohydrate content of foods and do not consider the effects of protein and fat on the stimulation of insulin secretion, they cannot provide a comprehensive approach to determine the insulin requirements.

CONCLUSION

Selecting foods based on carbohydrate counting, glycemic index or glycemic load are common guides to control glycemia in diabetic patients, but neglect the insulin response, thus leading to failure in diabetes management. Therefore, paying attention to insulinemic response along with glycemic response seems to be more effective in managing diabetes.

The influence of fasting and energy restricting diets on IGF-1 levels in humans: A systematic review and meta-analysis

BACKGROUND

Fasting and energy restricting diets have a potential means of delaying or preventing the onset of a range of age-related metabolic and neoplastic diseases. Consistently at the centre of this effect appears to be a significant reduction in circulating IGF-1 levels. The aim of the current systematic review and meta-analysis was to determine the influence of fasting and energy restriction on IGF-1 levels in human subjects.

METHODS

A comprehensive systematic search was conducted from onset of the database to February 2019 in Embase, MEDLINE/PubMed, and SCOPUS to identify randomized clinical trials that investigating the impact of fasting or energy restriction circulating IGF-1 levels. Effect size was reported as weighted mean difference (WMD) and 95% confidence intervals (CI) using a random-effects models. Subgroup analysis was performed to identify the probable source of heterogeneity among trials.

RESULTS

Total pooling of fasting and energy restriction randomised controlled trials in WMD analysis revealed no significant effect on circulating IGF-1 levels (WMD: -16.41 ng/ml, 95% CI: -35.88, 3.07). Sub grouped analysis fasting regimens appeared to substantially reduce IGF-1 (WMD: -28.87 ng/ml, 95% CI: -43.69, -14.05, I² = 00%), energy restricting regimens failed to do the same (WMD: -10.98 ng/ml, 95% CI: -33.08, 11.11, I² = 90%). Within this final subgrouping, it was observed that only energy restriction regimens of 50% or greater of normal daily energy intake were capable of significantly reducing IGF-1 levels (WMD: -36.57 ng/ml, 95% CI: -59.19, -13.95, I² = 00%). Finally, a meta regression were noted in which the percentage restriction of daily energy intake inversely correlated with plasma IGF-1 levels (p = 0.04).

CONCLUSION

This study uncovered that fasting significantly reduced levels of IGF-1, while energy restriction diets were successful only when intake was reduced by 50% or more.

Beta-Hydroxybutyrate Promotes Proliferation, Migration and Stemness in a Subpopulation of 5FU Treated SW480 Cells: Evidence for Metabolic Plasticity in Colon Cancer

Background: Beta-hydroxybutyrate (BHB) as a ketone body is the metabolic fuel in oxidative phosphorylation pathway. So far the effects of BHB on the biology of tumor cells is contradictory. Therefore, we investigated the effect of BHB on viability, metabolism, proliferation and migration of 5FU treated SW480 colon cancer cell line. Methods: we treated the SW480 cells with IC50 dose of 5-fluorouracil (5FU) for 72 h to isolate a subpopulation of 5FU treated cells that were resistant to it. Effects of BHB on cell viability was investigated by MTT assay. Measurement of oxygen consumption rate (OCR) in parallel with extracellular acidification rate (ECAR) upon BHB treatment was used for determination of metabolic profile of these cells. Investigating the relationship between metabolic phenotype and the status of differentiation and stemness was done by analyzing the expression of PGC-1α, c-MYC, NANOG, ALPi and KRT20 genes by qRT-PCR. Clonogenic and scratch assay were performed to determine the proliferation and migration abilities of incubated with BHB compared to untreated cells. Results: BHB increased cell viability in SW480 and 5FU treated SW480 cells. The results showed a significantly decreased ECAR and increased OCR in both cell types following BHB treatment reflecting the superiority of oxidative phosphorylation profile compared to glycolysis in both cell types. Also, treatment with BHB increases the expression of genes normally associated with stemness and mitochondrial biogenesis and decreases the expression of genes related to glycolytic program and differentiation in 5FU treated cells. Self-renewal and migration potential of BHB treated cells increased significantly. Conclusion: These findings suggest that BHB utilization via oxidative mitochondrial metabolism can fuel proliferation, migration and stemness in 5FU treated SW480 colon cancer cells.

Pomegranate Juice Increases Sirtuin1 Protein in Peripheral Blood Mononuclear Cell from Patients with Type 2 Diabetes: A Randomized Placebo Controlled Clinical Trial

BACKGROUND

Few studies have examined anti-inflammatory effects of pomegranate juice (PJ). The present study aimed to evaluate the effect of PJ on nuclear factor kappa B (NF-κB) p65 and sirtuin1 in peripheral blood mononuclear cell (PBMC), and plasma vascular inflammation biomarkers.

METHODS

Patients with type 2 diabetes were randomly assigned to either the PJ (n = 22) or the placebo group (n = 22). The patients in the PJ group received 250 mL of PJ daily for 12 weeks, whereas the placebo group received corresponding control beverages of similar color and energy content. At baseline and at the end of week 12, fasting plasma concentrations of soluble intercellular adhesion molecule type 1 (sICAM-1), soluble vascular cell adhesion molecule type 1 (sVCAM-1), and soluble E-selectin (sE-selectin) were measured. NF-κB p65 and SIRT1 were measured in the PBMC.

RESULTS

Plasma sE-selectin concentration decreased significantly in the PJ group at the end of week 12 compared to baseline (P < 0.001 for treatment effect), and the reduction was significant in comparison with the placebo group (P < 0.05 for treatment effect). There were no significant differences between the two groups in plasma sICAM-1 and sVCAM-1. At the end of the study, compared with the placebo group, NF-κB p65 in PBMC was significantly lower (P < 0.01 for treatment effect) and SIRT1 was significantly higher (P < 0.0001 for treatment effect) in the PJ group.

CONCLUSION

This study supports the PJ consumption as a food with potential benefits in individuals with type 2 diabetes as evidenced by improvements in NF-κB and SIRT1 levels in PBMC of study participants.

Cholesteryl ester transfer protein gene variations and macronutrient intakes interaction in relation to metabolic syndrome: Tehran lipid and glucose study

Objective(s):

There are controversial results regarding the effect of the interaction of CETP polymorphisms with dietary fats on the lipid profiles. The aim of this study was to examine the effect of CETP polymorphisms (rs5882 and rs3764261) and macronutrient intakes interaction in relation to metabolic syndrome (MetS) or its components.

Materials and Methods:

In this nested case-control study, subjects were selected from among participants of the Tehran Lipid and Glucose Study. Cases (n=441) were individually matched with two controls (844 non-MetS subjects). DNA samples were genotyped with HumanOmniExpress-24-v1-0 bead chips, including 649,932 SNP loci.

Results:

The mean ages at baseline were 38.1±10 and 37.0±10 years in women and 36.2±11 and 36.3±11 years in men, respectively in cases and controls. We did not find significant gene-diet interactions between rs5882 and dietary macronutrient intakes in relation to MetS risk. The risk of low HDL-C was lower in the first quartile of MUFA and total fat intake in G allele carriers, compared to AA genotype group. The risk of high BP appeared to increase significantly in higher quartiles of trans-fatty acid intakes (>1.81% of total energy intake) in G allele carriers compared with the AA genotype group. No significant interactions were found between rs3764261 and macronutrient intakes in association with MetS or its components.

Conclusion:

Our findings demonstrate that dietary fats modify the association of rs5882 and risk of low HDL-C and high blood pressure.

An investigation of the effects of curcumin on iron overload, hepcidin level, and liver function in β-thalassemia major patients: A double-blind randomized controlled clinical trial

This study investigated the effects of curcumin, the active polyphenol in turmeric, on iron overload, hepcidin level, and liver function in β-thalassemia major patients. This double-blind randomized controlled clinical trial was conducted on 68 β-thalassemia major patients. The subjects were randomly divided into 2 groups to receive either 500 mg curcumin capsules (total: 1,000 mg) twice daily or placebo for 12 weeks. Dietary intakes and biochemical variables including hemoglobin, transferrin saturation, total iron binding capacity, nontransferrin bound iron (NTBI), ferritin, hepcidin, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were assessed at the beginning and end of the trial. Curcumin significantly reduced serum levels of NTBI (2.83 ± 1.08 compared with 2.22 ± 0.97 μmol/L, p = .001), ALT (42.86 ± 11.15 compared with 40.60 ± 9.89 U/L, p = .018), and AST (49.45 ± 12.39 compared with 46.30 ± 10.85 U/L, p = .002) at the end of the study. Based on analysis of covariance, a significant decrease was also observed in levels of NTBI (2.22 ± 0.97 vs. 2.55 ± 0.94 μmol/L, p = .026), ALT (40.60 ± 9.89 vs. 45.01 ± 10.42 U/L, p = .004), and AST (46.30 ± 10.85 vs. 50.99 ± 9.36 U/L, p = .009) in curcumin group in comparison with placebo group. There were no significant changes in hepcidin and other variables in any of the 2 groups. Curcumin administration alleviated iron burden and liver dysfunction by reducing NTBI, ALT, and AST levels in patients with β-thalassemia major.

Signaling pathways linking inflammation to insulin resistance

Inflammation is closely linked to the pathogenesis of type 2 diabetes (T2D) and chronic inflammation is one of the main causes of insulin resistance. Insulin pathway is very important for the regulation of glucose, lipid, and energy homeostasis, growth and mitogenic. Proinflammatory mediators can be related to obesity and induce insulin- resistance in adipose tissue. Signaling pathways of transcription factors, particularly NF-κB signaling, are involved in insulin-sensitivity. In addition, the crosstalk between M1-M2 macrophage polarizing plays an essential role in insulin resistance by switching from an M1 to an M2 phenotype and also activation of transcription factors such as NF-κB and AP1. Here, we focus on the roles of transcription factors in inflammation-induced insulin resistance and their involvement in pathogenesis of insulin resistance.

Benefits of Curcumin Supplementation on Antioxidant Status in β-Thalassemia Major Patients: A Double-Blind Randomized Controlled Clinical Trial

Background: β-Thalassemia major, the most common inherited anemia in the world, is associated with imbalance in the oxidant-antioxidant system. The objective of this study was to evaluate the efficacy of curcumin supplementation on markers of oxidative stress in patients with β-Thalassemia. Methods: This double-blind randomized controlled clinical trial was performed on 61 β-thalassemia major patients. Subjects in the curcumin group received two 500 mg curcumin capsules daily and patients in the placebo group took 2 placebo capsules daily for 12 weeks. Dietary intakes and biochemical parameters were assessed at the beginning and the end of intervention. Results: At the end of the study, serum malondialdehyde (MDA), total and direct bilirubin significantly decreased (p = 0.002, p < 0.001, and p < 0.001, respectively) and total antioxidant capacity significantly increased (p = 0.005) in the curcumin group. Based on the analysis of covariance, a significant reduction in MDA, total and direct bilirubin was also detected in the curcumin group when compared to the placebo group (p = 0.001, p = 0.039, and p = 0.013, respectively). Changes in hemoglobin, serum iron, ferritin, catalase, and vitamin E were not significant in any of the 2 groups. Conclusions: Curcumin supplementation in combination with deferoxamin improved the antioxidant status in β-thalassemia major patients. Curcumin may be useful for the relief of metabolic complications in these patients.

Ball-Milling Promoted Monobromination Reactions: One-pot Regioselective Synthesis of Aryl Bromides and α-Bromoketones by NBS and Recyclable MCM-41-SO3H at Room Temperature

An effective approach to monobromination reactions utilizing room temperature ball-milling is introduced for the synthesis of aryl bromides and bromoketones with N-bromosuccinimide (NBS) and MCM-41-SO3H. Advantages of this technique are short reaction times and high regioselectivity. In contrast to other techniques using microwaves, ultrasound, or ionic liquids, handling of sensitive materials is possible and furthermore, this method has advantages over other solvent-free techniques that require a higher reaction temperature for high yield of products.

Ability of dairy fat in inducing metabolic syndrome in rats

Background

The risk of heart diseases, diabetes and stroke is increased with higher metabolic risk factors. Models of diseases resulting from high-calorie diets have a significant role in pathophysiologic analysis of metabolic syndrome in rodents; but, these diets are considerably different from each other in various studies and may not be very similar to the metabolic syndrome model in humans. This study sought to make a model close to the disease in humans. 20 five-week old male Wistar rats were randomly assigned to two groups. For one of the groups, a high-calorie diet with 416 calories per 100 g with dairy-based fat was considered and, for another group, a control diet was given for 12 weeks. Weight changes, lipid profile, glucose values, Blood pressure, insulin and HOMA indices, were measured for both groups and weight changes were compared using repeated measures and independent t test; also, serum results were compared using independent t test.

Results

Values of weight, glucose, insulin, lipid profile and blood pressure, except HDL, had a tangible difference between two groups at the end of the study. HOMA-IR, HOMA-B and HOMA-S indicates a significant difference between the two groups after consumption high-energy diet.

Conclusion

The present study showed ability of dairy fat in gaining weight, insulin resistance and metabolic syndrome and provided the necessity of paying serious attention to the amount of fat intake from dairy sources.

PTEN over-expression by resveratrol in acute lymphoblastic leukemia cells along with suppression of AKT/PKB and ERK1/2 in genotoxic stress

The bioactive components of dietary phytochemicals are in the spotlight of research institutes, due to their significant antioxidant activities and health-promoting properties. Resveratrol is a polyphenol which is found abundantly in grapes and berries and has long been known as a chemo-preventive agent. The main purpose of this study was to provide a new mechanistic insight into the growth inhibition of acute lymphoblastic leukemia cells by resveratrol along with a DNA damage agent. It was found that the treatment of pre-B ALL cells by resveratrol in the presence or absence of doxorubicin resulted in decreased cell viability and a synergistic increase in cytotoxicity. Cell death was accompanied by a significant increase in phosphorylated p53 at serine 15 and accumulation of PTEN. In addition, resveratrol inhibited the over-expression of p-AKT and p-ERK1/2. These findings clearly demonstrated that resveratrol and doxorubicin synergistically increase the cytotoxicity of pre-B ALL cells via the hyper-activation of two important tumor suppressor proteins and two major signal transduction pathways.

Relationship of p53 accumulation in peripheral tissues of high-fat diet-induced obese rats with decrease in metabolic and oncogenic signaling of insulin

This paper aimed to explore the role of p53 in adipose and some other peripheral tissues of a diet-induced obese model and targeted it using pharmacological approach to ameliorate diet-induced insulin resistance. Five week old male Wistar rats were randomly divided into three groups and fed on low-fat diet (13% control lean group), high-fat diet (41% obese group), or high-fat diet plus a single dose of pifithrin-α in the end of experiments (PFT group). Insulin, glucose, and other serum parameters were analyzed by standard colorimetric kits. Protein levels were evaluated by immunoblotting and immunofluorescence methods. After 12weeks, both body weight and insulin resistance were significantly higher in obese rats than in the control ones. P53 and PTEN protein levels were markedly elevated in peripheral tissues in addition to adipose tissues. AKT activation was decreased in the peripheral tissues of obese rats and was in correlation with the increase of p53 and PTEN level. Systemic pifithrin-α administration considerably diminished p53 levels and ameliorated AKT phosphorylation in all peripheral tissues including adipose tissues. Interestingly, the systemic inhibition of p53 was in correlation with improving insulin glucose at serum level. The present results clearly showed that p53 activation in peripheral tissues was in correlation with decreased insulin action. These results indicated p53 activation in the peripheral tissues of obese subjects as a protective mechanism against chronic insulin elevation, suggested that p53 could be a new target for the treatment of type 2 diabetes.

The role dietary of bioactive compounds on the regulation of histone acetylases and deacetylases: a review

Nutrigenomics is an area of epigenomics that explores and defines the rapidly evolving field of diet-genome interactions. Lifestyle and diet can significantly influence epigenetic mechanisms, which cause heritable changes in gene expression without changes in DNA sequence. Nutrient-dependent epigenetic variations can significantly affect genome stability, mRNA and protein expression, and metabolic changes, which in turn influence food absorption and the activity of its constituents. Dietary bioactive compounds can affect epigenetic alterations, which are accumulated over time and are shown to be involved in the pathogenesis of age-related diseases such as diabetes, cancer, and cardiovascular disease. Histone acetylation is an epigenetic modification mediated by histone acetyl transferases (HATs) and histone deacetylases (HDACs) critically involved in regulating affinity binding between the histones and DNA backbone. The HDAC-mediated increase in histone affinity to DNA causes DNA condensation, preventing transcription, whereas HAT-acetylated chromatin is transcriptionally active. HDAC and HAT activities are reported to be associated with signal transduction, cell growth and death, as well as with the pathogenesis of various diseases. The aim of this review was to evaluate the role of diet and dietary bioactive compounds on the regulation of HATs and HDACs in epigenetic diseases. Dietary bioactive compounds such as genistein, phenylisothiocyanate, curcumin, resveratrol, indole-3-carbinol, and epigallocatechin-3-gallate can regulate HDAC and HAT activities and acetylation of histones and non-histone chromatin proteins, and their health benefits are thought to be attributed to these epigenetic mechanisms. The intake of dietary compounds that regulate epigenetic modifications can provide significant health effects and may prevent various pathological processes involved in the development of cancer and other life-threatening diseases.

PI3K/AKT and Mdm2 activation are associated with inhibitory effect of cAMP increasing agents on DNA damage-induced cell death in human pre-B NALM-6 cells

DNA damage response (DDR) consists of both proapoptotic and prosurvival signaling branches. Superiority of each signaling branch determines the outcome of DNA damage: death or allowing the repair. The present authors have previously shown that an increased intracellular level of cAMP disrupts p53-mediated apoptosis in human pre-B NALM-6 cells and inhibition of NF-κB prevents prosurvival effect of cAMP during DNA damage. AKT/PKB (protein kinase B) is a general mediator of survival signaling. AKT signaling inhibits p53-mediated transcription and apoptosis. The results of present study showed that cAMP disrupted DNA damage/p53-mediated apoptosis through AKT and subsequent NF-κB activation. These results suggested that AKT may be found as part of a complex with scaffolding proteins, beta-arrestins and PDE4D. cAMP disarticulated the complex through binding to PDE4D compartment. It seems that release of AKT protein potentiated DDR activated pro-survival AKT in NALM-6 cells. Taken together, the present data indicated that regulation of AKT signaling may determine the fate of cells exposed to genotoxic stress.

cAMP protects acute promyelocytic leukemia cells from arsenic trioxide-induced caspase-3 activation and apoptosis

More recently, arsenic trioxide (ATO), was integrated into acute promyelocytic leukemia (APL) treatment, showing high efficacy and tolerability in patients with both ATRA-sensitive and ATRA-resistant APL. ATO could induce apoptosis at relatively high concentrations (0.5 to 2.0 micromol/L) and partial differentiation at low concentrations (0.1 to 0.5 micromol/L) in leukemic promyelocytes. It is known that cAMP agonists enhance low-dose ATO-induced APL cells differentiation. Less well appreciated was the possible interaction between relatively high-doses of ATO and enhanced levels of cAMP in APL cells. Here, we show that elevation of cAMP levels by forskolin inhibited ATO-mediated apoptosis in APL-derived NB4 cells, and this inhibition could be averted by cell permeable cAMP-dependent protein kinase inhibitor (14-22) amide. Inactivating phosphorylation of the proapoptotic protein Bad at Ser118 and phosphorylation of the CREB proto-oncogene at Ser133 were observed upon elevation of cAMP levels in NB4 cells. Phosphorylation of these PKA target proteins is known to promote cell survival in AML cells. The ability of cAMP to endow the APL cells with survival advantage is of particular importance when cAMP agonists may be considered as adjuncts to APL therapy.

Effects of pomegranate juice consumption on inflammatory markers in patients with type 2 diabetes: A randomized, placebo-controlled trial

BACKGROUND

Diabetes causes the increased concentration of circulatory cytokines as a result of inflammation. Considering that pomegranate juice (PJ) is known to have antioxidant and anti-inflammatory properties, the purpose of this study was to determine the effects of PJ consumption on markers of inflammation in patients with type 2 diabetes (T2D).

MATERIALS AND METHODS

In a randomized, double-blind clinical trial study, 50 patients with T2D (40-65 years old) were randomly assigned to one of two groups. Participants in each group received either 250 mL/day PJ or a control beverage for 12 weeks. Biochemical markers including fasting plasma glucose (FPG), insulin and inflammatory markers were assayed on the baseline and follow-up blood samples.

RESULTS

In all, 44 patients in two groups were included in the analysis: PJ (n = 22) and placebo (n = 22). After 12 weeks of intervention, in the PJ group, there were 32% and 30% significant decreases in plasma C-reactive protein (hs-CRP) and Interlukin-6, respectively (P < 0.05). The mean ± SD plasma interlukin-6 (7.1 ± 5.6 vs. 11.9 ± 14.4 mg/L) and hs-CRP (1791 ± 1657 and 1953 ± 1561 ng/mL) concentrations in the PJ group were significantly lower than the placebo group after intervention (P < 0.05).

CONCLUSION

PJ consumption by patients with T2D does not affect FPG or the insulin resistance index (HOMA-IR), whereas it does reduce Interlukin-6 and hs-CRP concentrations in plasma. Therefore, PJ consumption may have an anti-inflammatory effect in patients with T2D.

Synergistic anti-proliferative effect of resveratrol and etoposide on human hepatocellular and colon cancer cell lines

Resveratrol is an active component of grape, which has been shown to inhibit proliferation of a wide variety of tumor cells. The ability of resveratrol to enhance anti-proliferative effects of etoposide in wild type p53 liver carcinoma (HepG2) and colon cancer (HCT-116) cells was investigated with focusing on p53 activation. HepG2 cells and HCT-116 cells were treated with resveratrol and/or etoposide in a time- and dose-dependent manner and their proliferative response was evaluated by XTT assay. The expression of p53 protein was assessed using Western blot. Resveratrol exerted anti-proliferative activity on both cell types in a dose (25-100 μM)- and time (24-72 h)-dependent manner. Interestingly in HepG2 cells, resveratrol exhibited the same levels of cytotoxicity as etoposide (10 μM) when the cells treated with ≥ 25 μM for 48-72 h. In contrast to HepG2, resveratrol significantly enhanced anti-proliferative effects of etoposide in HCT-116 cells. P53 expression was up-regulated by resveratrol and etoposide and pre-incubation of both cells with resveratrol increased levels of etoposide-induced p53 expression. In line with cytotoxicity effect, combination therapy showed stronger activation of p53 in HCT-116 compared to HepG2. It seems that resveratrol exerts differential synergistic effect with etoposide on proliferation of cancer cells from different origin which is mainly accompanied by p53 activation. Our data represent a future strategy to provide much safer and more effective treatment for colon cancer.

Association of plasma nitric oxide concentration and endothelial nitric oxide synthase T-786C gene polymorphism in coronary artery disease

Nitric oxide (NO) is synthesized from l-arginine by endothelium nitric oxide synthase (NOS3) and plays important roles in many physiologic and pathologic processes. NO involved in the pathogenesis of coronary atherosclerosis. In the present study we hypothesized that polymorphisms of NOS gene might be associated with increased risk of coronary artery disease (CAD) and plasma NO concentrations. The eNOS gene polymorphism was investigated in 241 unrelated CAD patients with positive coronary angiograms and 261 ages matched control subjects without a history of symptomatic CAD. The NOS3 gene polymorphisms were analyzed by RFLP. Plasma NO, lipid profile and other risk factors were also assessed. The genotype frequencies for T-786C polymorphism differed significantly between CAD patients and controls (p=0.041). The mean plasma NO(x) concentrations showed significant differences according to genotypes of T-786C polymorphism in total population only. The mean plasma NO(x) increased in those individuals that are homozygote for C allele in promoter compared with those individuals are heterozygote for this allele and homozygote for T allele in total population and Controls, but no in CAD patients. The present study provides evidences that T-786C polymorphism of the NOS3 gene is associated with CAD. T-786C polymorphism was not associated with increased plasma NO in CAD patients.

The citrus flavonoid hesperidin induces p53 and inhibits NF-κB activation in order to trigger apoptosis in NALM-6 cells: involvement of PPARγ-dependent mechanism

BACKGROUND

Hesperidin, a flavanone present in citrus fruits, has been identified as a potent anticancer agent because of its proapoptotic and antiproliferative characteristics in some tumor cells. However, the precise mechanisms of action are not entirely understood.

AIM

The main purpose of this study is to investigate the involvement of peroxisome proliferator-activated receptor-gamma (PPARγ) in hesperidin's anticancer actions in human pre-B NALM-6 cells, which expresses wild-type p53.

METHODS

The effects of hesperidin on cell-cycle distribution, proliferation, and caspase-mediated apoptosis were examined in NALM-6 cells in the presence or absence of GW9662. The expression of peroxisome proliferator-activated receptor-gamma (PPARγ), p53, phospho-IκB, Bcl-2, Bax, and XIAP proteins were focused on using the immunoblotting assay. The transcriptional activities of PPARγ and nuclear factor-kappaB (NF-κB) were analyzed by the transcription factor assay kits. The expression of PPARγ and p53 was analyzed using the RT-PCR method.

RESULTS

Hesperidin induced the expression and transcriptional activity of PPARγ and promoted p53 accumulation and downregulated constitutive NF-κB activity in a PPARγ-dependent and PPARγ-independent manner. The growth-inhibitory effect of hesperidin was partially reduced when the cells preincubated with PPARγ antagonist prior to the exposure to hesperidin.

CONCLUSIONS

The findings of this study clearly demonstrate that hesperidin-mediated proapoptotic and antiproliferative actions are regulated via both PPARγ-dependent and PPARγ-independent pathways in NALM-6 cells. These data provide the first evidence that hesperidin could be developed as an agent against hematopoietic malignancies.

Elevation of cyclic AMP causes an imbalance between NF-kappaB and p53 in NALM-6 cells treated by doxorubicin

We previously showed that cAMP can inhibit DNA damage-induced wild type p53 accumulation in human pre-B NALM-6 cells, leading to a profound reduction of their apoptotic response. Here, we provide evidence for the potentiation of DNA damage-induced NF-kappaB activation by cAMP. We found that inhibition of NF-kappaB activation prevents the inhibitory effect of cAMP on doxorubicin-induced apoptosis. Moreover, cAMP exerts its inhibitory effect on doxorubicin-induced apoptosis in a PKA-independent manner. The present study also shows that elevation of cAMP prolongs the phosphorylation of IkappaB and subsequent activation of NF-kappaB in doxorubicin treated NALM-6 cells in a proteasome-dependent manner. Taken together, our results demonstrate that cAMP abrogates the balance between apoptotic and antiapoptotic transcription factors that are hallmarks of DNA damage signaling.

Endothelial nitric oxide synthase gene Glu298Asp polymorphism in patients with coronary artery disease

BACKGROUND AND OBJECTIVES

Endo-derived nitric oxide (NO) is synthesized from L-arginine by endothelial nitric oxide synthase (NOS3). Since reduced NO synthesis in endothelial cells has been implicated in the development of coronary atherosclerosis, we investigated the association of NOS3 gene polymorphisms and coronary artery disease (CAD) in an Iranian population.

SUBJECTS AND METHODS

We studied the NOS3 gene Glu298Asp polymorphism in 241 CAD patients with positive coronary angiograms (i.e.,> 50% stenosis affecting at least one coronary vessel) in Shahid Rajaee Heart Hospital and 261 control subjects without a history of symptomatic CAD. The NOS3 gene polymorphism was analyzed by polymerase chain reaction and restriction fragment length polymorphism. Lipid profile and other risk factors were also determined.

RESULTS

The genotype frequencies of Glu298Asp polymorphism for Glu/Glu, Glu/Asp, and Asp/Asp were 61.3%, 32.2%, and 6.5%, respectively, in control subjects, and 46.5%, 42.7%, and 10.8% in CAD patients, respectively. The genotype frequencies differed significantly between the two groups (P=.003). The frequencies of the Asp alleles were 32.2% and 22.6% for CAD patients and control subjects, respectively; the difference between the two groups was statistically significant (P=.001; odds ratio=1.6). Plasma lipids, except HDL-C, were also significantly increased in the CAD groups.

CONCLUSION

These results suggest that CAD is associated with Glu298Asp polymorphism of the NOS3 gene in our population and that this polymorphism is an independent risk factor for CAD.

Docosahexaenoic acid sensitizes Ramos cells to Gamma-irradiation-induced apoptosis through involvement of PPAR-gamma activation and NF-kappaB suppression

Gamma-irradiation (Gamma-IR) resistance is a character of many malignant cells that decreases the efficacy of radiotherapy. Although ionizing radiation activates multiple cellular factors that vary depending on dose and tissue specificity, the activation of nuclear factor-kappa B appears to be a well-conserved response in tumor cells exposed to Gamma-IR which can lead to the inhibition of radiation-induced apoptosis. Thus, inhibition of NF-kappaB activation is an important strategy to abolish radioresistance. Recently, we have demonstrated that docosahexaenoic acid (DHA; 22:6 n-3 polyunsaturated fatty acids)-induced apoptosis may occur via ligand-dependent transcription factor, peroxisome proliferator-activated receptors-gamma. Moreover, many reports described that activation of PPAR-gamma can lead to the induction of apoptosis through NF-kappaB inhibition. Therefore, we addressed the mechanism that NF-kappaB is a downstream target of DHA and may be involved in the process of radiosensitization. Ramos cells are a highly radiation-resistant and p53-deficient Burkitt's lymphoma cell line. The results of present study showed that cotreatment of Ramos cells with low doses of DHA and Gamma-IR leads to marked phosphorylation of IkappaB and translocation of p65/NF-kappaB to nucleus in parallel with increase in apoptosis. Preincubation of the cells with GW9662, a selective antagonist for PPAR-gamma, significantly prevented NF-kappaB activation profile. Taken together, these results suggest that low concentration of DHA inhibited Gamma-IR-induced activation of NF-kappaB and sensitized Ramos cells to IR-induced cytotoxicity. Pretreatment of Ramos cells with GW9662 abrogated the ability of DHA to inhibit Gamma-IR-induced activation of NF-kappaB and diminished the DHA radiosensitizing effect indicating that PPAR-gamma may act as a mediator of DHA in inhibition of NF-kappaB. Taken together, these results suggest that low concentration of DHA inhibited Gamma-IR-induced activation of NF-kappaB and sensitized Ramos cells to IR-induced cytotoxicity. Pretreatment of Ramos cells with GW9662 abrogated the ability of DHA to inhibit Gamma-IR-induced activation of NF-kappaB and diminished the DHA radiosensitizing effect indicating that PPAR-gamma may act as a mediator of DHA in inhibition of NF-kappaB.

Involvement of PPAR-gamma and p53 in DHA-induced apoptosis in Reh cells

Docosahexaenoeic acid (DHA, 22:6 n-3) is an omega-3 polyunsaturated fatty acid that is found in fish oil and exerts cytotoxic effect on a variety of cell lines. The molecular target, responsible for mediating this effect of DHA, still remains unknown. In this report, we presented experimental evidences for the role of PPAR-gamma in conveying the cytotoxic effect of DHA. We showed that DHA induces apoptosis in Reh and Ramos cells and apoptotic effect of DHA is inhibited by the PPAR-gamma antagonist GW9662, indicating that PPAR-gamma functions as the mediator of the apoptotic effect of DHA. Furthermore, our result showed that DHA induces the PPAR-gamma protein levels in both Reh and Ramos cells. Interestingly, DHA was found to induce the expression of p53 protein in Reh cells in a PPAR-gamma-dependent manner. The up-regulation of p53 protein by DHA kinetically correlated with the activation of caspase 9, caspase 3, and induction of apoptosis, suggesting a role for p53 in DHA-mediated apoptosis in Reh cells. Taken together, these findings suggest a new signaling pathway, DHA-PPAR-gamma-p53, in mediating the apoptotic effect of DHA in Reh cells.