3,5-Diiodo-L-Thyronine Activates Brown Adipose Tissue Thermogenesis in Hypothyroid Rats

3,5-diiodo-l-thyronine (T2), a thyroid hormone derivative, is capable of increasing energy expenditure, as well as preventing high fat diet-induced overweight and related metabolic dysfunction. Most studies to date on T2 have been carried out on liver and skeletal muscle. Considering the role of brown adipose tissue (BAT) in energy and metabolic homeostasis, we explored whether T2 could activate BAT thermogenesis. Using euthyroid, hypothyroid, and T2-treated hypothyroid rats (all maintained at thermoneutrality) in morphological and functional studies, we found that hypothyroidism suppresses the maximal oxidative capacity of BAT and thermogenesis, as revealed by reduced mitochondrial content and respiration, enlarged cells and lipid droplets, and increased number of unilocular cells within the tissue. In vivo administration of T2 to hypothyroid rats activated BAT thermogenesis and increased the sympathetic innervation and vascularization of tissue. Likewise, T2 increased BAT oxidative capacity in vitro when added to BAT homogenates from hypothyroid rats. In vivo administration of T2 to hypothyroid rats enhanced mitochondrial respiration. Moreover, UCP1 seems to be a molecular determinant underlying the effect of T2 on mitochondrial thermogenesis. In fact, inhibition of mitochondrial respiration by GDP and its reactivation by fatty acids were greater in mitochondria from T2-treated hypothyroid rats than untreated hypothyroid rats. In vivo administration of T2 led to an increase in PGC-1α protein levels in nuclei (transient) and mitochondria (longer lasting), suggesting a coordinate effect of T2 in these organelles that ultimately promotes net activation of mitochondrial biogenesis and BAT thermogenesis. The effect of T2 on PGC-1α is similar to that elicited by triiodothyronine. As a whole, the data reported here indicate T2 is a thyroid hormone derivative able to activate BAT thermogenesis.     

RBP4 Activates Antigen-Presenting Cells,Leading to Adipose Tissue Inflammation and Systemic Insulin Resistance

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Adipose Tissue Macrophages Promote Myelopoiesis and Monocytosis in Obesity

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Tumour-Derived Reg3A Educates Dendritic Cells to Promote Pancreatic Cancer Progression

As a pancreatic inflammatory marker, regenerating islet-derived protein 3A (Reg3A) plays a key role in inflammation-associated pancreatic carcinogenesis by promoting cell proliferation, inhibiting apoptosis, and regulating cancer cell migration and invasion. This study aimed to reveal a novel immuno-regulatory mechanism by which Reg3A modulates tumour-promoting responses during pancreatic cancer (PC) progression. In an in vitro Transwell system that allowed the direct co-culture of human peripheral blood-derived dendritic cells (DCs) and Reg3A-overexpressing/ silenced human PC cells, PC cell-derived Reg3A was found to downregulate CD80, CD83 and CD86 expression on educated DCs, increase DC endocytic function, inhibit DC-induced T lymphocyte proliferation, reduce IL-12p70 production, and enhance IL-23 production by DCs. The positive effect of tumour-derived Reg3A-educated human DCs on PC progression was demonstrated in vivo by intraperitoneally transferring them into PC-implanted severe combined immunodeficiency (SCID) mice reconstituted with human T cells. A Reg3A-JAK2/STAT3 positive feedback loop was identified in DCs educated with Reg3A. In conclusion, as a tumour-derived factor, Reg3A acted to block the differentiation and maturation of the most important antigen-presenting cells, DCs, causing them to limit their potential anti-tumour responses, thus facilitating PC escape and progression.     

Adiposity-Related Cancer and Functional Imaging of Brown Adipose Tissue

Objective: Brown adipose tissue (BAT) is involved in energy dissipation and cytokine production and is potentially beneficial for the human body. The aim of the paper is to review the literature on adiposity-related cancer and functional imaging of BAT.Methods: We performed a review on adiposity-related cancer and functional imaging of BAT. We extensively researched papers for information on BAT molecular biology, as well as functional imaging modalities.Results: Adipose tissue is linked to the development of many cancers. Multiple drugs including fenofibrate, spironolactone, and other substances, as well as experimental agents like β-3 receptor agonists, caffeine, green tea extract, medium chain triglycerides (MCTs), and adenosine are known to stimulate and activate BAT. However, cold and nonshivering thermogenesis are the main activators of BAT. BAT has been detected on both magnetic resonance imaging (MRI) and 18F-fluorodexoxyglucose positron emission tomography (18F-FDG-PET)-based imaging in multiple studies. Different methods of cold stimulation and static and dynamic protocols have been used to detect and image BAT. Factors like sex, fasting or fed state, surface skin temperature, and/or body mass index (BMI) may influence PET-based BAT detection. BAT has also been detected using MRI, ^99mTechnetium(Tc)-sestamibi, and 123I- metaiodobenzylguanidine single-photon emission computed tomography/computed tomography (MIBG SPECT/CT).Conclusions: Stimulation of BAT offers promise in the management of obesity-related conditions. Tracers like [¹⁵O]-H₂O, [¹¹C] acetate, and 18F-fluoro-6-thia-heptadecanoic acid (18F-FTHA) that measure BAT blood flow, oxygen utilization, and nonessential fatty acid (NEFA) uptake, respectively, have been studied in humans. Future studies should focus on BAT tissue generation by altering the genetic pathways of adiposity-linked genes.Abbreviations: BAT = brown adipose tissue BMI = body mass index CT = computed tomography 18F-FDG = 18F-fluorodexoxyglucose 18F-FTHA = 18F-fluoro-6- thia-heptadecanoic acid GLUT = glucose transporter MIBG = metaiodobenzylguanidine MRI = magnetic resonance imaging PET = positron emission tomography PPAR = peroxisome proliferator-activated receptor SPECT = single-photon emission computed tomography SUV = standard uptake value Tc = technetium UCP-1 = uncoupling protein 1 WAT = white adipose tissue     

A Novel Mechanism by Which Tissue Transglutaminase Activates Signaling Events That Promote Cell Survival

Tissue transglutaminase (tTG) functions as a GTPase and an acyl transferase that catalyzes the formation of protein cross-links. tTG expression is frequently up-regulated in human cancer, where it has been implicated in various aspects of cancer progression, including cell survival and chemo-resistance. However, the extent to which tTG cooperates with other proteins within the context of a cancer cell, versus its intrinsic ability to confer transformed characteristics to cells, is poorly understood. To address this question, we asked what effect the ectopic expression of tTG in a non-transformed cellular background would have on the behavior of the cells. Using NIH3T3 fibroblasts stably expressing a Myc-tagged form of tTG, we found that tTG strongly protected these cells from serum starvation-induced apoptosis and triggered the activation of the PI3-kinase/mTOR Complex 1 (mTORC1)/p70 S6-kinase pathway. We determined that tTG forms a complex with the non-receptor tyrosine kinase c-Src and PI3-kinase, and that treating cells with inhibitors to block tTG function (monodansylcadaverine; MDC) or c-Src kinase activity (PP2) disrupted the formation of this complex, and prevented tTG from activating the PI3-kinase pathway. Moreover, treatment of fibroblasts over-expressing tTG with PP2, or with inhibitors that inactivate components of the PI3-kinase pathway, including PI3-kinase ({"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002) and mTORC1 (rapamycin), ablated the tTG-promoted survival of the cells. These findings demonstrate that tTG has an intrinsic capability to stimulate cell survival through a novel mechanism that activates PI3-kinase signaling events, thus highlighting tTG as a potential target for the treatment of human cancer.     

Fibulin-2 Is a Driver of Malignant Progression in Lung Adenocarcinoma

The extracellular matrix of epithelial tumors undergoes structural remodeling during periods of uncontrolled growth, creating regional heterogeneity and torsional stress. How matrix integrity is maintained in the face of dynamic biophysical forces is largely undefined. Here we investigated the role of fibulin-2, a matrix glycoprotein that functions biomechanically as an inter-molecular clasp and thereby facilitates supra-molecular assembly. Fibulin-2 was abundant in the extracellular matrix of human lung adenocarcinomas and was highly expressed in tumor cell lines derived from mice that develop metastatic lung adenocarcinoma from co-expression of mutant K-ras and p53. Loss-of-function experiments in tumor cells revealed that fibulin-2 was required for tumor cells to grow and metastasize in syngeneic mice, a surprising finding given that other intra-tumoral cell types are known to secrete fibulin-2. However, tumor cells grew and metastasized equally well in Fbln2-null and -wild-type littermates, implying that malignant progression was dependent specifically upon tumor cell-derived fibulin-2, which could not be offset by other cellular sources of fibulin-2. Fibulin-2 deficiency impaired the ability of tumor cells to migrate and invade in Boyden chambers, to create a stiff extracellular matrix in mice, to cross-link secreted collagen, and to adhere to collagen. We conclude that fibulin-2 is a driver of malignant progression in lung adenocarcinoma and plays an unexpected role in collagen cross-linking and tumor cell adherence to collagen.     

Stromal Cells Derived from Visceral and Obese Adipose Tissue Promote Growth of Ovarian Cancers

Obesity, and in particular visceral obesity, has been associated with an increased risk of developing cancers as well as higher rates of mortality following diagnosis. The impact of obesity on adipose-derived stromal cells (ASC), which contribute to the formation of tumor stroma, is unknown. Here we hypothesized that visceral source and diet-induced obesity (DIO) changes the ASC phenotype, contributing to the tumor promoting effects of obesity. We found that ASC isolated from subcutaneous (SC-ASC) and visceral (V-ASC) white adipose tissue(WAT) of lean(Le) and obese(Ob) mice exhibited similar mesenchymal cell surface markers expression, and had comparable effects on ovarian cancer cell proliferation and migration. Obese and visceral derived ASC proliferated slower and exhibited impaired differentiation into adipocytes and osteocytes in vitro as compared to ASC derived from subcutaneous WAT of lean mice. Intraperitoneal co-injection of ovarian cancer cells with obese or visceral derived ASC, but not lean SC-ASC, increased growth of intraperitoneal ID8 tumors as compared to controls. Obese and V-ASC increased stromal infiltration of inflammatory cells, including CD3+ T cells and F4/80+ macrophages. Obese and visceral derived ASC, but not lean SC-ASC, increased expression of chemotactic factors IL-6, MIP-2, and MCP-1 when cultured with tumor cells. Overall, these results demonstrate that obese and V-ASC have a unique phenotype, with more limited proliferation and differentiation capacity but enhanced expression of chemotactic factors in response to malignant cells which support infiltration of inflammatory cells and support tumor growth and dissemination.     

JIP3 Activates Kinesin-1 Motility to Promote Axon Elongation

Kinesin-1 is a molecular motor responsible for cargo transport along microtubules and plays critical roles in polarized cells, such as neurons. Kinesin-1 can function as a dimer of two kinesin heavy chains (KHC), which harbor the motor domain, or as a tetramer in combination with two accessory light chains (KLC). To ensure proper cargo distribution, kinesin-1 activity is precisely regulated. Both KLC and KHC subunits bind cargoes or regulatory proteins to engage the motor for movement along microtubules. We previously showed that the scaffolding protein JIP3 interacts directly with KHC in addition to its interaction with KLC and positively regulates dimeric KHC motility. Here we determined the stoichiometry of JIP3-KHC complexes and observed approximately four JIP3 molecules binding per KHC dimer. We then determined whether JIP3 activates tetrameric kinesin-1 motility. Using an in vitro motility assay, we show that JIP3 binding to KLC engages kinesin-1 with microtubules and that JIP3 binding to KHC promotes kinesin-1 motility along microtubules. We tested the in vivo relevance of these findings using axon elongation as a model for kinesin-1-dependent cellular function. We demonstrate that JIP3 binding to KHC, but not KLC, is essential for axon elongation in hippocampal neurons as well as axon regeneration in sensory neurons. These findings reveal that JIP3 regulation of kinesin-1 motility is critical for axon elongation and regeneration.     

活体肺癌组织玻璃化保存的研究

保存活体的肺癌组织将为肺癌发病基因筛查和靶向药物筛选等体外实验研究提供更完整的样本信息. 本文对活体肺癌组织的玻璃化保存方法进行研究，首先采用针浸法玻璃化保存单块肺癌组织，对所需低温保护剂的浓度和平衡时间进行了优化；其次采用冻存管对多块肺癌组织样本进行玻璃化保存，对低温保护剂溶液体积以及平衡时间进行了优化；最后对慢速冷冻、不加低温保护剂快速冷冻、玻璃化冷冻3种冷冻方法的冻存效果进行比较并通过低温显微分析其冰晶损伤机理.结果表明，20% EG+20% DMSO+0.5 mol/L海藻糖作为低温保护剂，在平衡溶液和玻璃化溶液分别加载3 min和1 min时，针浸法和0.25 ml冻存管内玻璃化冻存，复苏后组织活力最高，分别约为79.96%与80.44%. 免疫组化显示玻璃化保存肺癌组织经过复苏后，相比慢速冷冻和无保护剂快速冷冻，组织结构损伤较小，组织内细胞TUNEL阳性表达较少. 低温显微结果表明，玻璃化保存组织内部及周围只出现少量细小冰晶，而慢速冷冻、快速冷冻组织皆出现明显冰晶.     

High-Fat Diet Triggers Inflammation-Induced Cleavage of SIRT1 in Adipose Tissue To Promote Metabolic Dysfunction

Adipose tissue plays an important role in storing excess nutrients and preventing ectopic lipid accumulation in other organs. Obesity leads to excess lipid storage in adipocytes, resulting in the generation of stress signals and the derangement of metabolic functions. SIRT1 is an important regulatory sensor of nutrient availability in many metabolic tissues. Here we report that SIRT1 functions in adipose tissue to protect from inflammation and obesity under normal feeding conditions, and to forestall the progression to metabolic dysfunction under dietary stress and aging. Genetic ablation of SIRT1 in adipose tissue leads to gene expression changes that highly overlap with changes induced by high-fat diet in wild-type mice, suggesting that dietary stress signals inhibit the activity of SIRT1. Indeed, we show that high-fat diet induces the cleavage of SIRT1 protein in adipose tissue by the inflammation-activated caspase-1, providing a link between dietary stress and predisposition to metabolic dysfunction.     

Rbf Activates the Myogenic Transcriptional Program to Promote Skeletal Muscle Differentiation

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Role of Deregulated microRNAs in Breast Cancer Progression Using FFPE Tissue

MicroRNAs (miRNAs) contribute to cancer initiation and progression by silencing the expression of their target genes, causing either mRNA molecule degradation or translational inhibition. Intraductal epithelial proliferations of the breast are histologically and clinically classified into normal, atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC). To better understand the progression of ductal breast cancer development, we attempt to identify deregulated miRNAs in this process using Formalin-Fixed, Paraffin-Embedded (FFPE) tissues from breast cancer patients. Following tissue microdissection, we obtained 8 normal, 4 ADH, 6 DCIS and 7 IDC samples, which were subject to RNA isolation and miRNA expression profiling analysis. We found that miR-21, miR-200b/c, miR-141, and miR-183 were consistently up-regulated in ADH, DCIS and IDC compared to normal, while miR-557 was uniquely down-regulated in DCIS. Interestingly, the most significant miRNA deregulations occurred during the transition from normal to ADH. However, the data did not reveal a step-wise miRNA alteration among discrete steps along tumor progression, which is in accordance with previous reports of mRNA profiling of different stages of breast cancer. Furthermore, the expression of MSH2 and SMAD7, two important molecules involving TGF-β pathway, was restored following miR-21 knockdown in both MCF-7 and Hs578T breast cancer cells. In this study, we have not only identified a number of potential candidate miRNAs for breast cancer, but also found that deregulation of miRNA expression during breast tumorigenesis might be an early event since it occurred significantly during normal to ADH transition. Consequently, we have demonstrated the feasibility of miRNA expression profiling analysis using archived FFPE tissues, typically with rich clinical information, as a means of miRNA biomarker discovery.     

Development and Characterization of a Preclinical Model of Breast Cancer Lung Micrometastatic to Macrometastatic Progression

Most cancer patients die with metastatic disease, thus, good models that recapitulate the natural process of metastasis including a dormancy period with micrometastatic cells would be beneficial in developing treatment strategies. Herein we report a model of natural metastasis that balances time to complete experiments with a reasonable dormancy period, which can be used to better study metastatic progression. The basis for the model is a 4T1 triple negative syngeneic breast cancer model without resection of the primary tumor. A cell titration from 500 to 15,000 GFP tagged 4T1 cells implanted into fat pad number four of immune proficient eight week female BALB/cJ mice optimized speed of the model while possessing metastatic processes including dormancy and beginning of reactivation. The frequency of primary tumors was less than 50% in animals implanted with 500–1500 cells. Although implantation with over 10,000 cells resulted in 100% primary tumor development, the tumors and macrometastases formed were highly aggressive, lacked dormancy, and offered no opportunity for treatment. Implantation of 7,500 cells resulted in >90% tumor take by 10 days; in 30–60 micrometastases in the lung (with many animals also having 2–30 brain micrometastases) two weeks post-implantation, with the first small macrometastases present at five weeks; many animals displaying macrometastases at five weeks and animals becoming moribund by six weeks post-implantation. Using the optimum of 7,500 cells the efficacy of a chemotherapeutic agent for breast cancer, doxorubicin, given at its maximal tolerated dose (MTD; 1 mg/kg weekly) was tested for an effect on metastasis. Doxorubicin treatment significantly reduced primary tumor growth and lung micrometastases but the number of macrometastases at experiment end was not significantly affected. This model should prove useful for development of drugs to target metastasis and to study the biology of metastasis.