Adipose Tissue Dysfunction as Determinant of Obesity-Associated Metabolic Complications.

Obesity is a critical risk factor for the development of type 2 diabetes (T2D), and its prevalence is rising worldwide. White adipose tissue (WAT) has a crucial role in regulating systemic energy homeostasis. Adipose tissue expands by a combination of an increase in adipocyte size (hypertrophy) and number (hyperplasia). The recruitment and differentiation of adipose precursor cells in the subcutaneous adipose tissue (SAT), rather than merely inflating the cells, would be protective from the obesity-associated metabolic complications. In metabolically unhealthy obesity, the storage capacity of SAT, the largest WAT depot, is limited, and further caloric overload leads to the fat accumulation in ectopic tissues (e.g., liver, skeletal muscle, and heart) and in the visceral adipose depots, an event commonly defined as "lipotoxicity." Excessive ectopic lipid accumulation leads to local inflammation and insulin resistance (IR). Indeed, overnutrition triggers uncontrolled inflammatory responses in WAT, leading to chronic low-grade inflammation, therefore fostering the progression of IR. This review summarizes the current knowledge on WAT dysfunction in obesity and its associated metabolic abnormalities, such as IR. A better understanding of the mechanisms regulating adipose tissue expansion in obesity is required for the development of future therapeutic approaches in obesity-associated metabolic complications.

Altered H3K4me3 profile at the TFAM promoter causes mitochondrial alterations in preadipocytes from first-degree relatives of type 2 diabetics.

BACKGROUND: First-degree relatives of type 2 diabetics (FDR) exhibit a high risk of developing type 2 diabetes (T2D) and feature subcutaneous adipocyte hypertrophy, independent of obesity. In FDR, adipose cell abnormalities contribute to early insulin-resistance and are determined by adipocyte precursor cells (APCs) early senescence and impaired recruitment into the adipogenic pathway. Epigenetic mechanisms signal adipocyte differentiation, leading us to hypothesize that abnormal epigenetic modifications cause adipocyte dysfunction and enhance T2D risk. To test this hypothesis, we examined the genome-wide histone profile in APCs from the subcutaneous adipose tissue of healthy FDR. RESULTS: Sequencing-data analysis revealed 2644 regions differentially enriched in lysine 4 tri-methylated H3-histone (H3K4me3) in FDR compared to controls (CTRL) with significant enrichment in mitochondrial-related genes. These included TFAM, which regulates mitochondrial DNA (mtDNA) content and stability. In FDR APCs, a significant reduction in H3K4me3 abundance at the TFAM promoter was accompanied by a reduction in TFAM mRNA and protein levels. FDR APCs also exhibited reduced mtDNA content and mitochondrial-genome transcription. In parallel, FDR APCs exhibited impaired differentiation and TFAM induction during adipogenesis. In CTRL APCs, TFAM-siRNA reduced mtDNA content, mitochondrial transcription and adipocyte differentiation in parallel with upregulation of the CDKN1A and ZMAT3 senescence genes. Furthermore, TFAM-siRNA significantly expanded hydrogen peroxide (H2O2)-induced senescence, while H2O2 did not affect TFAM expression. CONCLUSIONS: Histone modifications regulate APCs ability to differentiate in mature cells, at least in part by modulating TFAM expression and affecting mitochondrial function. Reduced H3K4me3 enrichment at the TFAM promoter renders human APCs senescent and dysfunctional, increasing T2D risk.

Effects of standardized Cannabis sativa extract and ionizing radiation in melanoma cells in vitro.

CONTEXT: Melanoma causes the highest number of skin cancer-related deaths worldwide. New treatment methods are essential for the management of this life-threatening disease. AIMS: In this study, we investigated the efficacy of a standardized Cannabis sativa extract alone or in combination with single radiation dose (6 Gy) in B16F10 mouse melanoma cells in an extract dose-dependent manner. MATERIALS AND METHODS: C. sativa extract at three concentrations (25, 12.5, and 6.25 µg/mL) alone for 72 h or in combination with radiation (24 h incubation after the extract treatment + 48 h incubation after exposure to radiation) were evaluated for cell viability of melanoma cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cells were also treated with 6.25 µg/mL extract alone for 72 h before analyzing C. sativa-induced cell death by flow cytometry. RESULTS: Administration of the extract alone or alongside radiation substantially inhibited melanoma cell viability and proliferation in the extract dose response-dependent manner. The inhibition of melanoma cell viability was paralleled by an increase in necrosis but not apoptosis when melanoma cells were treated with the extract alone. Radiation alone did not have any antiproliferative effects, and radiation also did not synergize antiproliferative effects of the extract when the extract and radiation were combined. CONCLUSION: Our data suggest that C. sativa extract may have significant health and physiological implications for the treatment of melanoma. The results of this study also indicate that B16F10 mouse melanoma cells are radioresistant. Taken together, these findings may lead to the identification of new therapeutic strategy for the management of melanoma.

Low-dose Bisphenol-A Promotes Epigenetic Changes at Pparγ Promoter in Adipose Precursor Cells.

Exposure to endocrine-disrupting chemicals such as Bisphenol-A (BPA) is associated with an increase in obesity prevalence. Diet is the primary cause of human exposure to this contaminant. BPA promotes obesity by inducing adipocyte dysfunction and altering adipogenesis. Contradictory evidence and unanswered questions are reported in the literature concerning the BPA effects on adipogenesis. To clarify this issue, we tested the effects of prolonged low-dose BPA exposure on different phases of adipogenesis in committed 3T3L1 and uncommitted NIH3T3 preadipocytes. Our findings show that BPA effects on the adipogenesis are mediated by epigenetic mechanisms by reducing peroxisome proliferator-activated receptor gamma (Pparγ) promoter methylation in preadipocytes. Nevertheless, in BPA-exposed 3T3L1, Pparγ expression only transiently increases as lipid accumulation at day 4 of differentiation, without altering the adipogenic potential of the precursor cells. In the absence of differentiation mix, BPA does not make the 3T3L1 an in vitro model of spontaneous adipogenesis and the effects on the Pparγ expression are still limited at day 4 of differentiation. Furthermore, BPA exposure does not commit the NIH3T3 to the adipocyte lineage, although Pparγ overexpression is more evident both in preadipocytes and during the adipocyte differentiation. Interestingly, termination of the BPA exposure restores the Pparγ promoter methylation and inflammatory profile of the 3T3L1 cells. This study shows that BPA induces epigenetic changes in a key adipogenic gene. These modifications are reversible and do not affect preadipocyte commitment and/or differentiation. We identify an alternative transcriptional mechanism by which BPA affects gene expression and demonstrate how the challenge of preventing exposure is fundamental for human health.

Evaluation of effects of morphine and ionizing radiation in cancer cell lines.

PURPOSE: Breast and cervical cancers are the two most common cancers among women worldwide. Morphine is a potent analgesic for cancer pain, and radiation therapy is a conventional treatment for cancer. Unfortunately, the combined adjuvant cellular effects of morphine and ionizing radiation in cancer cells are largely unknown. MATERIALS AND METHODS: In this study, we examined the effects of morphine and single radiation dose of 2 Gy on viability and survival fraction of human breast cancer cell line MDA-MB 231 and human cervical cancer cell line HeLa, by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assays. We were also interested in evaluating these effects in human umbilical vein endothelial cells as well. RESULTS: We found that morphine did not have a dose- and time-dependent manner in endothelial, breast, and cervical cancer cells in vitro. It seems that pretreatment of breast and cervical cancer cells with morphine at some doses before irradiation reduces the cytotoxic effect of radiation. We also observed that endothelial cells were less sensitive than breast and cervical cancer cells to radiation or morphine + radiation. Based on the results of endothelial cells, morphine or radiation might not have a selective effect on the viability and clonogenic survival of different cell lines. CONCLUSIONS: Our data may suggest that morphine and radiotherapy could not be administered together to breast and cervical cancer patients if additional and in vivo studies confirm our results.

Chronic Adipose Tissue Inflammation Linking Obesity to Insulin Resistance and Type 2 Diabetes.

Obesity is one of the major health burdens of the 21st century as it contributes to the growing prevalence of its related comorbidities, including insulin resistance and type 2 diabetes. Growing evidence suggests a critical role for overnutrition in the development of low-grade inflammation. Specifically, chronic inflammation in adipose tissue is considered a crucial risk factor for the development of insulin resistance and type 2 diabetes in obese individuals. The triggers for adipose tissue inflammation are still poorly defined. However, obesity-induced adipose tissue expansion provides a plethora of intrinsic signals (e.g., adipocyte death, hypoxia, and mechanical stress) capable of initiating the inflammatory response. Immune dysregulation in adipose tissue of obese subjects results in a chronic low-grade inflammation characterized by increased infiltration and activation of innate and adaptive immune cells. Macrophages are the most abundant innate immune cells infiltrating and accumulating into adipose tissue of obese individuals; they constitute up to 40% of all adipose tissue cells in obesity. In obesity, adipose tissue macrophages are polarized into pro-inflammatory M1 macrophages and secrete many pro-inflammatory cytokines capable of impairing insulin signaling, therefore promoting the progression of insulin resistance. Besides macrophages, many other immune cells (e.g., dendritic cells, mast cells, neutrophils, B cells, and T cells) reside in adipose tissue during obesity, playing a key role in the development of adipose tissue inflammation and insulin resistance. The association of obesity, adipose tissue inflammation, and metabolic diseases makes inflammatory pathways an appealing target for the treatment of obesity-related metabolic complications. In this review, we summarize the molecular mechanisms responsible for the obesity-induced adipose tissue inflammation and progression toward obesity-associated comorbidities and highlight the current therapeutic strategies.

Coffee consumption and risk of nonmelanoma skin cancer: a dose-response meta-analysis.

Several epidemiological studies have evaluated the associations between coffee consumption and the risk of skin cancer; however, the results were not conclusive. This systematic review and meta-analysis of the cohort and case-control studies was carried out to determine the association between coffee intake and the risk of nonmelanoma skin cancer. Studies were identified by searching the PubMed and MEDLINE databases (to November 2015). Study-specific risk estimates were pooled under the random-effects model. We separately estimated the relative risk of the three conditions, for exposure to different doses of coffee consumption, kind of study design, and analysis restricted to the basal cell carcinoma type. The summary relative risks for nonmelanoma skin cancer were 0.96 [95% confidence interval (CI): 0.92-0.99] for one cup of coffee, 0.92 (95% CI: 0.88-0.97) for one to two cups of coffee, 0.89 (95% CI: 0.86-0.93) for two to three cups of coffee, and 0.81 (95% CI: 0.77-0.85) for more than three cups of coffee per day, respectively. This meta-analysis suggested that caffeinated coffee might have chemopreventive effects against basal cell carcinoma dose dependently. However, other prospective studies are warranted to confirm these effects.

Display of human and rabbit monocyte chemoattractant protein-1 on human embryonic kidney 293T cell surface.

Monocyte chemoattractant protein-1 (MCP-1/CCL2) is a protein that is secreted immediately upon endothelial injury, and thereby it plays a key role in inflammation via recruitment of leucocytes to the site of inflammation at the beginning and throughout the inflammatory processes. Aim of this study was to develop two separate cell lines displaying either human MCP-1 (HMCP-1) or rabbit MCP-1 (RMCP-1) on their surface. A DNA fragment containing HMCP-1- or RMCP-1-encoding sequence was inserted into a pcDNA plasmid. Escherichia coli cells strain TOP 10F' was separately transformed with the pcDNA/RMCP-1 or /HMCP-1 ligation mixture. Following the cloning and construct verification, human embryonic kidney cell line (HEK 293T) was transfected with either of the linearized plasmids. Plasmid integration into the genomic DNA of HEK 293T cells was verified by polymerase chain reaction (PCR). HMCP-1 and RMCP-1 expression was evaluated at RNA and protein levels by real-time PCR and flow cytometry, respectively. PCR products of the expected sizes were amplified from the chromosomal DNA of transfected HEK 293T cells, i.e. 644 bp for H-MCP1 and 737 bp for RMCP-1 constructs. Real-time PCR revealed that the copy numbers of RMCP1 and HMCP1 mRNA per cell were 294 and 500, respectively. Flow cytometry analysis indicated 85% for RMCP-1 and 87% for HMCP-1 expression levels on the surface of transfected cells, when compared with an isotype control. The experiments thus confirmed that the MCP-1 genes were integrated into the HEK 293T genomic DNA and the encoded proteins were stably expressed on the cell surface.

The Role of N-Acetylcysteine in Platelet Aggregation and Reperfusion Injury in Recent Years.

BACKGROUND: N-acetylcysteine (NAC) is an amino acid that contains a cysteine group and is currently used widely in various fields of medical research especially in cardiology. In this review, potential benefits of NAC in the aggregation of platelet and reperfusion injury are evaluated. METHODS: The available evidence was collected by searching Scopus, Pub-Med, Medline, Cochrane central register of controlled trials, and Cochrane database systematic reviews. Our searching was performed without time limitation and only English language articles were included in this review. Key words used as search terms included "N-acetylcysteine", "platelet aggregation", "reperfusion injury". RESULTS: Over the past decade, several investigations were carried out to ascertain reperfusion injury and antiplatelet properties of NAC, and in this article the results of investigations in both models (human and animal) were addressed in detail. The results revealed that NAC has an important antiplatelet property in animal models while this effect is not very significant in human models and needs more investigations. However, its reperfusion injury in both models is worth noticing. CONCLUSION: Due to the limited data about effectiveness of NAC in both human and animal as antiplatelet agent, more investigation is needed to evaluate NAC efficacy in platelet aggregation and reperfusion injury especially in human studies in the future.