Inflamed tumor-associated adipose tissue is a depot for macrophages that stimulate tumor growth and angiogenesis

Adipose Tissue Analysis Toolkit (ATAT) for automated analysis of adipocyte size and extracellular matrix in white adipose tissue

OBJECTIVE

The pathological expansion of white adipose tissue (WAT) in obesity involves adipocyte hypertrophy accompanied by expansion of the collagen-rich pericellular extracellular matrix (ECM) and development of crown-like structures (CLS). Traditionally, WAT morphology is assessed through immunohistochemical analysis of WAT sections. However, manual analysis of large histological sections is time-consuming, and the available digital tools for analyzing adipocyte size and pericellular ECM are limited. To address this gap, the authors developed the Adipose Tissue Analysis Toolkit (ATAT), an ImageJ plugin facilitating analysis of adipocyte size, WAT ECM, and CLS.

METHODS AND RESULTS

ATAT utilizes local and image-level differentials in pixel intensity to independently threshold image background, distinguishing adipocyte-free tissue without user input. It accurately captures adipocytes in histological sections stained with common dyes and automates the analysis of adipocyte cross-sectional area, total-field, and localized region-of-interest ECM. ATAT allows fully automated batch analysis of histological images using default or user-defined adipocyte detection parameters.

CONCLUSIONS

ATAT provides several advantages over existing WAT image analysis tools, enabling high-throughput analyses of adipocyte-specific parameters and facilitating the assessment of ECM changes associated with WAT remodeling due to weight changes and other pathophysiological alterations that affect WAT function.

Phenotype-specific melanoma uptake of fatty acid from human adipocytes activates AXL and CAV1-dependent β-catenin nuclear accumulation

Phenotypic diversity of cancer cells within tumors generated through bi-directional interactions with the tumor microenvironment has emerged as a major driver of disease progression and therapy resistance. Nutrient availability plays a critical role in determining phenotype, but whether specific nutrients elicit different responses on distinct phenotypes is poorly understood. Here we show, using melanoma as a model, that only MITF Low undifferentiated cells, but not MITF High cells, are competent to drive lipolysis in human adipocytes. In contrast to MITF High melanomas, adipocyte-derived free fatty acids are taken up by undifferentiated MITF Low cells via a fatty acid transporter (FATP)-independent mechanism. Importantly, oleic acid (OA), a monounsaturated long chain fatty acid abundant in adipose tissue and lymph, reprograms MITF Low undifferentiated melanoma cells to a highly invasive state by ligand-independent activation of AXL, a receptor tyrosine kinase associated with therapy resistance in a wide range of cancers. AXL activation by OA then drives SRC-dependent formation and nuclear translocation of a β-catenin-CAV1 complex. The results highlight how a specific nutritional input drives phenotype-specific activation of a pro-metastasis program with implications for FATP-targeted therapies.

Adipose Tissue Analysis Toolkit (ATAT) for Automated Analysis of Adipocyte Size and Extracellular Matrix in White Adipose Tissue

Objective

The pathological expansion of white adipose tissue (WAT) in obesity involves adipocyte hypertrophy accompanied by expansion of collagen-rich pericellular extracellular matrix (ECM) and the development of crown-like structures (CLS). Traditionally, WAT morphology is assessed through immunohistochemical analysis of WAT sections. However, manual analysis of large histological sections is time-consuming, and available digital tools for analyzing adipocyte size and pericellular ECM are limited. To address this gap, we developed the Adipose Tissue Analysis Toolkit (ATAT), an ImageJ plugin facilitating analysis of adipocyte size, WAT ECM and CLS.

Methods and Results

ATAT utilizes local and image-level differentials in pixel intensity to independently threshold background, distinguishing adipocyte-free tissue without user input. It accurately captures adipocytes in histological sections stained with common dyes and automates the analysis of adipocyte cross-sectional area, total-field, and localized region-of-interest ECM. ATAT allows fully automated batch analysis of histological images using default or user-defined adipocyte detection parameters.

Conclusions

ATAT provides several advantages over existing WAT image analysis tools, enabling high-throughput analyses of adipocyte-specific parameters and facilitating the assessment of ECM changes associated with WAT remodeling due to weight changes and other pathophysiological alterations that affect WAT function.

Study Importance Questions

What is already known about this subject?: The manual analysis of large WAT histological sections is very time-consuming, while digital tools for the analysis of WAT are limited.What are the new findings in your manuscript?: - ATAT enables fully automated analysis of batches of histological images using either default or user-defined adipocyte detection parameters- ATAT allows high-throughput analyses of adipocyte-specific parameters and pericellular extracellular matrix- ATAT enables the assessment of fibrotic changes associated with WAT remodeling and crown-like structuresHow might your results change the direction of research or the focus of clinical practice?: - ATAT is designed to work with histological sections and digital images obtained using a slide scanner or a microscope.- This tool will help basic and clinical researchers to conduct automated analyses of adipose tissue histological sections.

Innate lymphoid cells and tumor-derived lactic acid: novel contenders in an enduring game

Aerobic glycolysis, also known as the Warburg effect, has for a prolonged period of time been perceived as a defining feature of tumor metabolism. The redirection of glucose utilization towards increased production of lactate by cancer cells enables their rapid proliferation, unceasing growth, and longevity. At the same time, it serves as a significant contributor to acidification of the tumor microenvironment, which, in turn, imposes substantial constraints on infiltrating immune cells. Here, we delve into the influence of tumor-derived lactic acid on innate lymphoid cells (ILCs) and discuss potential therapeutic approaches. Given the abundance of ILCs in barrier tissues such as the skin, we provide insights aimed at translating this knowledge into therapies that may specifically target skin cancer.

Melanoma cells induce dedifferentiation and metabolic changes in adipocytes present in the tumor niche

BACKGROUND

One of the factors that affect the progression of melanoma is the tumor microenvironment, which consists of cellular elements, extracellular matrix, acidification, and a hypoxic state. Adipocytes are one of the types of cell present in the niche and are localized in the deepest layer of the skin. However, the relationship between fat cells and melanoma remains unclear.

METHODS

We assessed the influence of melanoma cells on adipocytes using an indirect coculture system. We estimated the level of cancer-associated adipocyte (CAA) markers through quantitative PCR analysis. The fibroblastic phenotype of CAAs was confirmed by cell staining and western blotting analysis. The lipid content was estimated by lipid detection in CAAs using LipidSpot and by quantitative analysis using Oil Red O. The expression of proteins involved in lipid synthesis, delipidation, and metabolic processes were assessed through quantitative PCR or western blotting analysis. Lactate secretion was established using a Lactate-Glo™ assay. Proteins secreted by CAAs were identified in cytokine and angiogenesis arrays. The proliferation of melanoma cells cocultured with CAAs was assessed using an XTT proliferation assay. Statistical analysis was performed using a one-way ANOVA followed by Tukey's test in GraphPad Prism 7 software.

RESULTS

Obtained CAAs were identified by decreased levels of leptin, adiponectin, resistin, and FABP4. Adipocytes cocultured with melanoma presented fibroblastic features, such as a similar proteolytic pattern to that of 3T3L1 fibroblasts and increased levels of vimentin and TGFβRIII. Melanoma cells led to a reduction of lipid content in CAAs, possibly by downregulation of lipid synthesis pathways (lower FADS, SC4MOL, FASN) or enhancement of lipolysis (higher level of phosphorylation of ERK and STAT3). Adipocytes cocultured with melanoma cells secreted higher IL6 and SerpinE1 levels and produced less CCL2, CXCL1, and angiogenic molecules. CAAs also showed metabolic changes comprising the increased secretion of lactate and enhanced production of glucose, lactate, and ion transporters. In addition, changes in adipocytes observed following melanoma coculture resulted in a higher proliferation rate of cancer cells.

CONCLUSIONS

Melanoma cells led to decreased lipid content in adipocytes, which might be related to enhanced delipidation or reduction of lipid synthesis. Fibroblast-like CAAs showed metabolic changes that may be the reason for accelerated proliferation of melanoma cells.

Extracellular Lactic Acidosis of the Tumor Microenvironment Drives Adipocyte-to-Myofibroblast Transition Fueling the Generation of Cancer-Associated Fibroblasts

Lactic acidosis characterizes the tumor microenvironment (TME) and is involved in the mechanisms leading to cancer progression and dissemination through the reprogramming of tumor and local host cells (e.g., endothelial cells, fibroblasts, and immune cells). Adipose tissue also represents a crucial component of the TME which is receiving increasing attention due to its pro-tumoral activity, however, to date, it is not known whether it could be affected by the acidic TME. Now, emerging evidence from chronic inflammatory and fibrotic diseases underlines that adipocytes may give rise to pathogenic myofibroblast-like cells through the adipocyte-to-myofibroblast transition (AMT). Thus, our study aimed to investigate whether extracellular acidosis could affect the AMT process, sustaining the acquisition by adipocytes of a cancer-associated fibroblast (CAF)-like phenotype with a pro-tumoral activity. To this purpose, human subcutaneous adipose-derived stem cells committed to adipocytes (acADSCs) were cultured under basal (pH 7.4) or lactic acidic (pH 6.7, 10 mM lactate) conditions, and AMT was evaluated with quantitative PCR, immunoblotting, and immunofluorescence analyses. We observed that lactic acidosis significantly impaired the expression of adipocytic markers while inducing myofibroblastic, pro-fibrotic, and pro-inflammatory phenotypes in acADSCs, which are characteristic of AMT reprogramming. Interestingly, the conditioned medium of lactic acidosis-exposed acADSC cultures was able to induce myofibroblastic activation in normal fibroblasts and sustain the proliferation, migration, invasion, and therapy resistance of breast cancer cells in vitro. This study reveals a previously unrecognized relationship between lactic acidosis and the generation of a new CAF-like cell subpopulation from adipocytic precursor cells sustaining tumor malignancy.

High-Fat Diet as a Risk Factor for Breast Cancer: A Meta-Analysis

High-fat diets have been identified as a major cause of obesity and a potential risk factor for breast cancer. Fat tissue, also known as adipose tissue, produces an excess of estrogen, which has been linked to an increased risk of breast cancer. Determining the impact of HFDs in the development and progression of breast cancer is essential, as it will enable us to identify the role of dietary modification in preventing and managing the disease. The impact of a high-fat diet (HFD) on the development of breast cancer in humans has yet to be fully explained, as very few human studies are available to effectively analyze the effect fatty food has on breast cancer development. This meta-analysis, therefore, seeks to determine the strength of association, if any, between HFD and an increased risk of breast cancer development. This research will help inform good eating habits, potentially reducing the disease's incidence and outcome. This meta-analysis examined eight (8) papers from various nations examining the effect of a high-fat diet as a risk factor for breast cancer development between 2010 and 2020. The study employed the multivariable-adjusted hazard ratio (H.R.), odds ratio (OR), or relative risk (R.R.) from the studies. Breast cancer cases were histologically and radiologically confirmed in the studies evaluated, and validated food frequency questionnaires were used to assess their dietary patterns. This metanalysis study found a substantial link between a high-fat diet and an increased risk of breast cancer, with statistically significant results (I² = 93.38%, p0.05). Changes in dietary fat consumption may thus help mitigate some of the unfavorable consequences of breast cancer and survival. Even if further research is needed to support this assertion, the findings are compelling enough to advocate for low-fat, healthy diets to avoid breast cancer.

Therapeutic Potential of Thymoquinone in Triple-Negative Breast Cancer Prevention and Progression through the Modulation of the Tumor Microenvironment

To date, the tumor microenvironment (TME) has gained considerable attention in various areas of cancer research due to its role in driving a loss of immune surveillance and enabling rapid advanced tumor development and progression. The TME plays an integral role in driving advanced aggressive breast cancers, including triple-negative breast cancer (TNBC), a pivotal mediator for tumor cells to communicate with the surrounding cells via lymphatic and circulatory systems. Furthermore, the TME plays a significant role in all steps and stages of carcinogenesis by promoting and stimulating uncontrolled cell proliferation and protecting tumor cells from the immune system. Various cellular components of the TME work together to drive cancer processes, some of which include tumor-associated adipocytes, fibroblasts, macrophages, and neutrophils which sustain perpetual amplification and release of pro-inflammatory molecules such as cytokines. Thymoquinone (TQ), a natural chemical component from black cumin seed, is widely used traditionally and now in clinical trials for the treatment/prevention of multiple types of cancer, showing a potential to mitigate components of TME at various stages by various pathways. In this review, we focus on the role of TME in TNBC cancer progression and the effect of TQ on the TME, emphasizing their anticipated role in the prevention and treatment of TNBC. It was concluded from this review that the multiple components of the TME serve as a critical part of TNBC tumor promotion and stimulation of uncontrolled cell proliferation. Meanwhile, TQ could be a crucial compound in the prevention and progression of TNBC therapy through the modulation of the TME.

Innate Lymphoid Cells in Skin Homeostasis and Malignancy

Innate lymphoid cells (ILCs) are mostly tissue resident lymphocytes that are preferentially enriched in barrier tissues such as the skin. Although they lack the expression of somatically rearranged antigen receptors present on T and B cells, ILCs partake in multiple immune pathways by regulating tissue inflammation and potentiating adaptive immunity. Emerging evidence indicates that ILCs play a critical role in the control of melanoma, a type of skin malignancy thought to trigger immunity mediated mainly by adaptive immune responses. Here, we compile our current understanding of ILCs with regard to their role as the first line of defence against melanoma development and progression. We also discuss areas that merit further investigation. We envisage that the possibility to harness therapeutic potential of ILCs might benefit patients suffering from skin malignancies such as melanoma.

Multi‑faceted role of cancer‑associated adipocytes in the tumor microenvironment (Review)

Adipocytes are a type of stromal cell found in numerous different tissues that serve an active role in the tumor microenvironment. Cancer-associated adipocytes (CAAs) display a malignant phenotype and are found at the invasive tumor front, which mediates the crosstalk network between adipocytes (the precursor cells that will become cancer-associated adipocytes in the future) and cancer cells. The present review covers the mechanisms of adipocytes in the development of cancer, including metabolic reprogramming, chemotherapy resistance and adipokine regulation. Furthermore, the potential mechanisms involved in the adipocyte-cancer cell cycle in various types of cancer, including breast, ovarian, colon and rectal cancer, are discussed. Deciphering the complex network of CAA-cancer cell crosstalk will provide insights into tumor biology and optimize therapeutic strategies.

Tumor-Derived Lactic Acid Contributes to the Paucity of Intratumoral ILC2s

Group 2 innate lymphoid cells (ILC2s) are abundant in non-lymphoid tissues and increase following infectious and inflammatory insults. In solid tumors, however, ILC2s constitute a relatively small proportion of immune cells. Here, we show, using melanoma as a model, that while the IL-33/IL C2/eosinophil axis suppresses tumor growth, tumor-derived lactate attenuates the function and survival of ILC2s. Melanomas with reduced lactate production (LDHA^low) are growth delayed and typified by an increased number of ILC2s compared with control tumors. Upon IL-33 stimulation, ILC2s accompanied by eosinophils more effectively restrain the growth of LDHA^low tumors than control melanomas. Furthermore, database analysis reveals a negative correlation between the expression of LDHA and markers associated with ILC2s and the association of high expression of IL33 and an eosinophil marker SIGLEC8 with better overall survival in human cutaneous melanoma patients. This work demonstrates that the balance between the IL-33/ILC2/eosinophil axis and lactate production by tumor cells regulates melanoma growth.

Obesity considerations during the COVID-19 outbreak

The worldwide population is facing a double burden of epidemic, the COVID-19 and obesity. This is even more alarming as obesity increases the COVID-19 severity. However, the relationship between obesity and COVID-19 severity is more complex than a simple association with BMI. In particular, obesity has been associated with low death rates in patients with acute respiratory distress syndrome, a fatal comorbidity to COVID-19, possibly due to the obesity paradox. Also, visceral adiposity could be a major risk factor for COVID-19 severity, due to its immune activation component, release of angiotensin-converting enzyme 2 and involvement in the cytokine storm, hypercoagulability and embolism. A poor antioxidant nutritional status also weakens the immune system, increasing inflammation and infection risk. Moreover, the COVID-19 lockdown might impact lifestyle patterns, mental health and weight bias, worsening the obesity then COIVD-19 situation. On the other hand, health care expenses and productivity loss are expected to increase during the concomitant epidemics. The co-occurrence of obesity and COVID-19 is a major challenge at both public health and economic levels that should urgently be taken into consideration. The identification of COVID-19 weight related risk factors and the development of appropriate weight management programs are needed to tackle the concomitant epidemics.

Stromal Cells Present in the Melanoma Niche Affect Tumor Invasiveness and Its Resistance to Therapy

Malignant melanoma is a highly metastatic type of cancer, which arises frequently from transformed pigment cells and melanocytes as a result of long-term UV radiation exposure. In recent years, the incidence of newly diagnosed melanoma patients reached 5% of all cancer cases. Despite the development of novel targeted therapies directed against melanoma-specific markers, patients' response to treatment is often weak or short-term due to a rapid acquisition of drug resistance. Among the factors affecting therapy effectiveness, elements of the tumor microenvironment play a major role. Melanoma niche encompasses adjacent cells, such as keratinocytes, cancer-associated fibroblasts (CAFs), adipocytes, and immune cells, as well as components of the extracellular matrix and tumor-specific physicochemical properties. In this review, we summarize the current knowledge concerning the influence of cancer-associated cells (keratinocytes, CAFs, adipocytes) on the process of melanomagenesis, tumor progression, invasiveness, and the emergence of drug resistance in melanoma. We also address how melanoma can alter the differentiation and activation status of cells present in the tumor microenvironment. Understanding these complex interactions between malignant and cancer-associated cells could improve the development of effective antitumor therapeutic strategies.

Resistance Mechanisms of Anti-angiogenic Therapy and Exosomes-Mediated Revascularization in Cancer

Anti-angiogenic therapies (AATs) have been widely used for cancer treatment. But the beneficial effects of AATs are short, because AAT-induced tumor revascularization facilitates the tumor relapse. In this mini-review, we described different forms of tumor neovascularization and revascularization including sprouting angiogenesis, vessel co-option, intussusceptive angiogenesis, and vasculogenic mimicry, all of which are closely mediated by vascular endothelial growth factor (VEGF), angiopoietins, matrix metalloproteinases, and exosomes. We also summarized the current findings for the resistance mechanisms of AATs including enhancement in pro-angiogenic cytokines, heterogeneity in tumor-associated endothelial cells (ECs), crosstalk between tumor cells and ECs, masking of extracellular vesicles, matrix stiffness and contributions from fibroblasts, macrophages and adipocytes in the tumor microenvironment. We highlighted the revascularization following AATs, particularly the role of exosome stimulating factors such as hypoxia and miRNA, and that of exosomal cargos such as cytokines, miRNAs, lncRNAs, and circRNAs from the tumor ECs in angiogenesis and revascularization. Finally, we proposed that renormalization of tumor ECs would be a more efficient cancer therapy than the current AATs.

The Influence of Tumor Microenvironment on Immune Escape of Melanoma

The low efficiency of currently-used anti-cancer therapies poses a serious challenge, especially in the case of malignant melanoma, a cancer characterized by elevated invasiveness and relatively high mortality rate. The role of the tumor microenvironment in the progression of melanoma and its acquisition of resistance to treatment seems to be the main focus of recent studies. One of the factors that, in normal conditions, aids the organism in its fight against the cancer and, following the malignant transformation, adapts to facilitate the development of the tumor is the immune system. A variety of cell types, i.e., T and B lymphocytes, macrophages, and dendritic and natural killer cells, as well as neutrophils, support the growth and invasiveness of melanoma cells, utilizing a plethora of mechanisms, including secretion of pro-inflammatory molecules, induction of inhibitory receptors expression, or depletion of essential nutrients. This review provides a comprehensive summary of the processes regulated by tumor-associated cells that promote the immune escape of melanoma cells. The described mechanisms offer potential new targets for anti-cancer treatment and should be further studied to improve currently-employed therapies.

Studying Adipose Tissue in the Breast Tumor Microenvironment In Vitro: Progress and Opportunities

BACKGROUND

The breast cancer microenvironment contains a variety of stromal cells that are widely implicated in worse patient outcomes. While many in vitro models of the breast tumor microenvironment have been published, only a small fraction of these feature adipocytes. Adipocytes are a cell type increasingly recognized to have complex functions in breast cancer.

METHODS

In this review, we examine findings from recent examples of in vitro experiments modeling adipocytes within the local breast tumor microenvironment.

RESULTS

Both two-dimensional and three-dimensional models of adipocytes in the breast tumor microenvironment are covered in this review and both have uncovered interesting phenomena related to breast tumor progression.

CONCLUSION

Certain aspects of breast cancer and associated adipocyte biology: extracellular matrix effects, cell-cell contact, and physiological mass transport can only be examined with a three-dimensional culture platform. Opportunities remain for innovative improvements to be made to in vitro models that further increase what is known about adipocytes during breast cancer progression.

Triptolide-nanoliposome-APRPG, a novel sustained-release drug delivery system targeting vascular endothelial cells, enhances the inhibitory effects of triptolide on laser-induced choroidal neovascularization

PURPOSE

To investigate whether triptolide-nanoliposome-APRPG (TP-nanolip-APRPG), a novel sustained-release nano-drug delivery system that targets vascular endothelial cells, could enhance the inhibition of triptolide (TP) on laser-induced choroidal neovascularization (CNV).

METHODS

TP was encapsulated with or without APRPG (Ala-Pro-Arg-Pro-Gly) peptide-modified nanoliposomes. CNV was induced by laser photocoagulation in C57BL/6J mice. One microliter of 10 μg free TP monomer, TP-nanolip containing 10 μg TP, TP-nanolip-APRPG containing 10 μg TP, or an identical volume of PBS was intravitreally injected in mice immediately after laser photocoagulation. Seven days after laser photocoagulation, CNV volumes were calculated in each group. Infiltration of M2 macrophages as well as protein levels of vascular endothelial growth factor (VEGF) and inflammatory factors including ICAM-1 and MCP-1 in the RPE-choroid complex were determined. In vitro assays for cell proliferation, migration, and tube formation were also performed.

RESULTS

TP-nanolip-APRPG was successfully synthesized and exhibited good TP delivery and enhanced the cellular uptake of TP in vitro. In vitro studies showed that TP-nanolip-APRPG was a better inhibitor of cell proliferation (31.34 ± 3.89 % vs 41.25 ± 4.67 % vs 53.55 ± 5.76 %), migration (62.60 ± 8.88 vs 104.60 ± 13.32 vs 147.00 ± 13.15), and tube formation (681.26 ± 108.15 vs 926.75 ± 54.01 vs 1189.84 ± 157.14) than TP-nanolip or free TP (all P < 0.05). Intravitreal injections of free TP (77588.10±7719.28 μm³), TP-nanolip (64628.23 ± 5857.96 μm³), and TP-nanolip-APRPG (50880.34 ± 6606.56 μm³) inhibited the development of CNV compared with the PBS control group (120338.07 ± 17428.90 μm³) (P < 0.01, n=6). TP-nanolip-APRPG and TP-nanolip significantly down-regulated the protein levels of VEGF (152.76±19.55 vs 182.24±19.98 vs 208.55±21.93 pg/mg total protein) and inflammatory factors including ICAM-1 (61.69±3.49 vs 72.04±3.49 vs 81.92±4.09 ng/mg total protein) and MCP-1 (40.14±3.50 vs 50.75±4.18 vs 60.27±5.23 pg/mg total protein) compared with the free TP monomer group (all P < 0.05, n=8), which paralleled the decreased infiltration of M2 macrophages in the CNV lesions. Moreover, no influence on retinal morphology and function was observed before or after treatment in each group (P > 0.05, n=6).

CONCLUSIONS

TP-nanolip-APRPG, a novel sustained-release drug delivery system targeting endothelial cells of CNV lesions, could enhance TP inhibition of the development of CNV without toxicity in the retina, suggesting therapeutic potential for CNV-related diseases in future clinical practice.

Obesity and the Impact on Cutaneous Melanoma: Friend or Foe?

Excess body weight has been identified as a risk factor for many types of cancers, and for the majority of cancers, it is associated with poor outcomes. In contrast, there are cancers in which obesity is associated with favorable outcomes and this has been termed the “obesity paradox”. In melanoma, the connection between obesity and the increased incidence is not as strong as for other cancer types with some but not all studies showing an association. However, several recent studies have indicated that increased body mass index (BMI) improves survival outcomes in targeted and immune therapy treated melanoma patients. The mechanisms underlying how obesity leads to changes in therapeutic outcomes are not completely understood. This review discusses the current evidence implicating obesity in melanoma progression and patient response to targeted and immunotherapy, and discusses potential mechanisms underpinning these associations.

Functional roles of GDF15 in modulating microenvironment to promote carcinogenesis

Obesity and related metabolic dysregulation are risk factors for many types of cancer. The interactions between a developing tumor and its microenvironment are known to implicate a complex "crosstalk" among the factors produced by the population of cells. Among these factors, Growth and differentiation factor 15 (GDF15) has a functional role in cancer. GDF15 expression is induced in response to the conditions associated with cellular stress and diseases. The GDF15 receptor, a member of the glial-cell-derived neurotropic factor family (GDNF), is a GDNF family receptor α-like (GFRAL) protein. GDF15 induces pro-angiogenic effects in tumors. However, GDF15 could affect tumorigenesis both positively and negatively. With a better understanding of the upstream disease pathways reflected by GDF15, new treatment targets may emerge.

Breast Adipocyte Co-culture Increases the Expression of Pro-angiogenic Factors in Macrophages

Obese individuals with breast cancer have a poorer prognosis and higher risk of metastatic disease vs. non-obese patients. Adipose tissue in obese individuals is characterized by an enhanced macrophage infiltration, creating a microenvironment that favors tumor progression. Here, we demonstrate a role for adipocyte-macrophage interactions in the regulation of angiogenesis. Co-culture of THP-1 macrophages with human breast adipocytes led to increased expression of the pro-angiogenic growth factor, vascular endothelial growth factor A (VEGFA). Several adipocyte-derived proteins including leptin, insulin, IL-6, and TNF-α were each capable of increasing VEGFA expression in THP-1 macrophages, identifying these as possible mediators of the changes that were observed with co-culture. Furthermore, analysis of THP-1 culture media by antibody array revealed that THP-1 secrete several other pro-angiogenic signals in response to adipocyte co-culture, including interleukin 8 (IL-8), matrix metalloproteinase 9 (MMP9), pentraxin 3 (PTX3), and serpin E1 (plasminogen activator inhibitor 1, PAI1) after co-culture with human adipocytes. We used an in vitro endothelial tube formation assay with human vascular endothelial cells to evaluate the effects of THP-1 culture media on angiogenesis. Here, culture media from THP-1 cells previously exposed to human adipocytes stimulated endothelial tube formation more significantly than THP-1 cells cultured alone. In summary, we find that adipocyte co-culture stimulates the expression of pro-angiogenic mediators in macrophages and has pro-angiogenic effects in vitro, thus representing a possible mechanism for the enhanced risk of breast cancer progression in obese individuals.

Inflammation related miRNAs as an important player between obesity and cancers

The growing trend in addition to their burden, prevalence, and death has made obesity and cancer two of the most concerning diseases worldwide. Obesity is an important risk factor for common types of cancers where the risk of some cancers is directly related to the obesity. Various inflammatory mechanisms and increased level of pro-inflammatory cytokines have been investigated in many previous studies, which play key roles in the pathophysiology and development of both of these conditions. On the other hand, in the recent years, many studies have individually focused on the biomarker's role and therapeutic targeting of microRNAs (miRNAs) in different types of cancers and obesity including newly discovered small noncoding RNAs (sncRNAs) which regulate gene expression and RNA silencing. This study is a comprehensive review of the main inflammation related miRNAs in obesity/obesity related traits. For the first time, the main roles of miRNAs in obesity related cancers have been discussed in response to the question raised in the following hypothesis; do the main inflammatory miRNAs link obesity with obesity-related cancers regarding their role as biomarkers? Graphical abstractConceptual design of inflammatory miRNAs which provide link between obesity and cancers.

Progression or suppression: Two sides of the innate lymphoid cells in cancer

Innate lymphoid cells (ILCs) as key players in innate immunity have been shown to be significantly associated with inflammation, lymphoid neogenesis, tissue remodeling, mucosal immunity and lately have been considered a remarkable nominee for either tumor-promoting or tumor-inhibiting functions. This dual role of ILCs, which is driven by intrinsic and extrinsic factors like plasticity of ILCs and the tumor microenvironment, respectively, has aroused interest in ILCs subsets in past decade. So far, numerous studies in the cancer field have revealed ILCs to be key players in the initiation, progression and inhibition of tumors, therefore providing valuable insights into therapeutic approaches to utilize the immune system against cancer. Herein, the most recent achievements regarding ILCs subsets including new classifications, their transcription factors, markers, cytokine release and mechanisms that led to either progression or inhibition of many tumors have been evaluated. Additionally, the available data regarding ILCs in most prevalent cancers and new therapeutic approaches are summarized.

Obesity-Associated Extracellular Matrix Remodeling Promotes a Macrophage Phenotype Similar to Tumor-Associated Macrophages

Obesity is associated with adipose inflammation, defined by macrophages encircling dead adipocytes, as well as extracellular matrix (ECM) remodeling and increased risk of breast cancer. Whether ECM affects macrophage phenotype in obesity is uncertain. A better understanding of this relationship could be strategically important to reduce cancer risk or improve outcomes in the obese. Using clinical samples, computational approaches, and in vitro decellularized ECM models, this study quantified the relative abundance of pro-inflammatory (M1) and anti-inflammatory (M2) macrophages in human breast adipose tissue, determined molecular similarities between obesity and tumor-associated macrophages, and assessed the regulatory effect of obese versus lean ECM on macrophage phenotype. Our results suggest that breast adipose tissue contains more M2- than M1-biased macrophages across all body mass index categories. Obesity further increased M2-biased macrophages but did not affect M1-biased macrophage density. Gene Set Enrichment Analysis suggested that breast tissue macrophages from obese versus lean women are more similar to tumor-associated macrophages. These changes positively correlated with adipose tissue interstitial fibrosis, and in vitro experiments indicated that obese ECM directly stimulates M2-biased macrophage functions. However, mammographic density cannot be used as a clinical indicator of these changes. Collectively, these data suggest that obesity-associated interstitial fibrosis promotes a macrophage phenotype similar to tumor-associated macrophages, which may contribute to the link between obesity and breast cancer.

HSP90 inhibitor PU-H71 increases radiosensitivity of breast cancer cells metastasized to visceral organs and alters the levels of inflammatory mediators

Heat shock protein 90 (HSP90) inhibitors are considered as new radiosensitizing agents. PU-H71, a novel HSP90 inhibitor, is under evaluation for the treatment of advanced cancer. It is however not known whether PU-H71 alters radiosensitivity of metastatic breast cancer. Hence, we here evaluated mechanisms of possible anti-tumoral and radiosensitizing effects of PU-H71 on breast carcinoma cells metastasized to vital organs such as the liver and brain. The effect of PU-H71 on proliferation of breast carcinoma cells was determined using 4T1 cells and its brain (4TBM), liver (4TLM), and heart (4THM) metastatic subsets as well as non-metastatic 67NR cells. Changes in radiation sensitivity were determined by clonogenic assays. Changes in client proteins and levels of angiogenic and inflammatory mediators from these cancer cell cultures and ex vivo cultures were detected. PU-H71 alone inhibited ERK1/2, p38, and Akt activation and reduced N-cadherin and HER2 which further documented the anti-tumoral effects of PU-H71. The combination of PU-H71 and radiotherapy induced cytotoxic effect than PU-H71 alone, and PU-H71 showed a radiosensitizing effect in vitro. On the other hand, PU-H71 and radiation co-treatment increased p38 phosphorylation which is one of the hallmarks of inflammatory response. Accordingly, IL-6 secretion was increased following PU-H71 and radiotherapy co-treatment ex vivo. Levels of angiogenic and inflammatory factors such as MIP-2, SDF-1, and VEGF were increased under in vitro conditions but not under ex vivo conditions. These results demonstrated for the first time that PU-H71 enhances therapeutic effects of radiotherapy especially in highly metastatic breast carcinoma but a possible increase in inflammatory response should also be considered.

Blockade of Lymphangiogenesis Shapes Tumor-Promoting Adipose Tissue Inflammation

Tumor-associated lymphangiogenesis correlates with lymph node metastasis and poor outcome in several human malignancies. In addition, the presence of functional lymphatic vessels regulates the formation of tumor inflammatory and immune microenvironments. Although lymphatic structures are often found deeply integrated into the fabric of adipose tissue, the impact of lymphangiogenesis on tumor-associated adipose tissue (AT) has not yet been investigated. Using K14-VEGFR3-Ig mice that constitutively express soluble vascular endothelial growth factor receptor (VEGFR) 3-Ig in the skin, scavenging VEGF-C and VEGF-D, the role of lymphangiogenesis in the generation of an inflammatory response within tumor-associated AT was studied. Macrophages expressing lymphatic vessel endothelial hyaluronan receptor-1 were found within peritumoral adipose tissue from melanoma-bearing K14-VEGFR3-Ig mice, which were further enriched with alternatively activated macrophages based on surface marker CD301/C-type lectin domain family 10 member A expression. The blockade of lymphangiogenesis also resulted in accumulation of the cytokine IL-6, which correlated with enhanced macrophage proliferation of the alternatively activated phenotype. Furthermore, melanomas co-implanted with freshly isolated adipose tissue macrophages grew more robustly than melanomas growing alone. In human cutaneous melanomas, adipocyte-selective FABP4 transcripts closely correlated with gene signatures of CLEC10A and were associated with poor overall survival. These data suggest that the blockade of pathways regulating lymphatic vessel formation shapes an inflammatory response within tumor-associated AT by facilitating accumulation of tumor-promoting alternatively activated macrophages.

Peritumoural adipose tissue pro-inflammatory cytokines are associated with tumoural growth factors in cancer cachexia patients

BACKGROUND

Cancer cachexia (CC) is a multifactorial syndrome, often irreversible, that affects patients with cancer influenced, in part, by the inflammatory condition. Peritumoural adipose tissue produces adipokines and angiogenic, apoptotic, and growth factors; given the possible crosstalk between the peritumoural adipose tissue and tumour, these may play an important role in cancer biology and carcinogenesis.

METHODS

The aim of this study was to evaluate the factors produced by peritumoural adipose tissue in a cohort of 16 colorectal cancer patients with either weight-stable cancer (WSC; n = 7) or CC (n = 9). The study was approved by the Ethics Research Committee (972.914). Samples of peritumoural adipose tissue were analysed for concentrations of TNF-α, IL-1β, STAT-1, STAT-3, RANTES, IL-1Ra, IP-10, IL-15, MCP-1, IFN-α, GCSF, FADD, and TGF-β. The cytokines and proteins were measured using Multiplex. Correlations between the proteins and cytokines were evaluated.

RESULTS

TNF-α, STAT-1, and FADD, a factor involved in apoptosis, were significantly higher in CC group than in the WSC group. In the peritumoural adipose tissue of the CC group, RANTES showed a significant positive correlation with IL-1Ra and IP-10 and a negative correlation with IFN-α; and GCSF showed significant negative correlations with IL-1Ra, IP-10, IL-15, and MCP-1 and a positive correlation with IFN-α. In the peritumoural adipose tissue of the WSC group, no significant correlations were detected between RANTES, GCSF, IL-3, FADD, and STAT-1 and the cytokines/chemokines analysed.

CONCLUSIONS

These results indicated that inflammatory and tumorigenic pathways were altered in peritumoural adipose tissue in CC. Furthermore, inflammatory cytokines were correlated with growth factors in the peritumoural adipose tissue of cachectic patients, suggesting that inflammatory cytokines modulated the proliferative environment closely linked to the tumour.

Micro-environment and intracellular metabolism modulation of adipose tissue macrophage polarization in relation to chronic inflammatory diseases

The accumulation and pro-inflammatory polarization of immune cells, mainly macrophages, in adipose tissue (AT) are considered crucial factors for obesity-induced chronic inflammatory diseases. In this review, we highlighted the role of adipose tissue macrophage (ATM) polarization on AT function in the obese state and the effect of the micro-environment and intracellular metabolism on the dynamic switch of ATMs into their pro-inflammatory or anti-inflammatory phenotypes, which may have distinct influences on obesity-related chronic inflammatory diseases. Obesity-associated metabolic dysfunctions, including those of glucose, fatty acid, cholesterol, and other nutrient substrates such as vitamin D and iron in AT, promote the pro-inflammatory polarization of ATMs and AT inflammation via regulating the interaction between ATMs and adipocytes and intracellular metabolic pathways, including glycolysis, fatty acid oxidation, and reverse cholesterol transportation. Focusing on the regulation of ATM metabolism will provide a novel target for the treatment of obesity-related chronic inflammatory diseases, including insulin resistance, cardiovascular diseases, and cancers.

Adipocyte-Derived Lipids Mediate Melanoma Progression via FATP Proteins

Advanced, metastatic melanomas frequently grow in subcutaneous tissues and portend a poor prognosis. Though subcutaneous tissues are largely composed of adipocytes, the mechanisms by which adipocytes influence melanoma are poorly understood. Using in vitro and in vivo models, we find that adipocytes increase proliferation and invasion of adjacent melanoma cells. Additionally, adipocytes directly transfer lipids to melanoma cells, which alters tumor cell metabolism. Adipocyte-derived lipids are transferred to melanoma cells through the FATP/SLC27A family of lipid transporters expressed on the tumor cell surface. Among the six FATP/SLC27A family members, melanomas significantly overexpress FATP1/SLC27A1. Melanocyte-specific FATP1 expression cooperates with BRAF^V600E in transgenic zebrafish to accelerate melanoma development, an effect that is similarly seen in mouse xenograft studies. Pharmacologic blockade of FATPs with the small-molecule inhibitor Lipofermata abrogates lipid transport into melanoma cells and reduces melanoma growth and invasion. These data demonstrate that stromal adipocytes can drive melanoma progression through FATP lipid transporters and represent a new target aimed at interrupting adipocyte-melanoma cross-talk.Significance: We demonstrate that stromal adipocytes are donors of lipids that mediate melanoma progression. Adipocyte-derived lipids are taken up by FATP proteins that are aberrantly expressed in melanoma. Inhibition of FATPs decreases melanoma lipid uptake, invasion, and growth. We provide a mechanism for how stromal adipocytes drive tumor progression and demonstrate a novel microenvironmental therapeutic target. Cancer Discov; 8(8); 1006-25. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 899.

Impaired lymphatic function accelerates cancer growth

Increased lymphangiogenesis is a common feature of cancer development and progression, yet the influence of impaired lymphangiogenesis on tumor growth is elusive. C3HBA breast cancer and KHT-1 sarcoma cell lines were implanted orthotopically in Chy mice, harboring a heterozygous inactivating mutation of vascular endothelial growth factor receptor-3, resulting in impaired dermal lymphangiogenesis. Accelerated tumor growth was observed in both cancer models in Chy mice, coinciding with reduced peritumoral lymphangiogenesis. An impaired lymphatic washout was observed from the peritumoral area in Chy mice with C3HBA tumors, and the number of macrophages was significantly reduced. While fewer macrophages were detected, the fraction of CD163+ M2 macrophages remained constant, causing a shift towards a higher M2/M1 ratio in Chy mice. No difference in adaptive immune cells was observed between wt and Chy mice. Interestingly, levels of pro- and anti-inflammatory macrophage-associated cytokines were reduced in C3HBA tumors, pointing to an impaired innate immune response. However, IL-6 was profoundly elevated in the C3HBA tumor interstitial fluid, and treatment with the anti-IL-6 receptor antibody tocilizumab inhibited breast cancer growth. Collectively, our data indicate that impaired lymphangiogenesis weakens anti-tumor immunity and favors tumor growth at an early stage of cancer development.

Monocyte chemotactic protein-1 deficiency reduces spontaneous metastasis of Lewis lung carcinoma in mice fed a high-fat diet

Adipose-produced pro-inflammatory cytokines contribute to obesity and cancer. This 2×2 experiment was designed to investigate effects of monocyte chemotactic protein-1 (MCP-1) deficiency on pulmonary metastasis of Lewis lung carcinoma (LLC) in MCP-1 deficient and wild-type mice fed a modified AIN93G diet containing 16% and 45% of energy from corn oil, respectively. The high-fat diet significantly increased the number and size (cross-sectional area and volume) of lung metastases compared to the AIN93G control diet. Deficiency in MCP-1 reduced lung metastases by 37% in high-fat diet-fed mice; it reduced metastatic cross-sectional area by 46% and volume by 69% compared to wild-type mice. Adipose and plasma concentrations of MCP-1 were significantly higher in high-fat diet-fed wild-type mice than in their AIN93G-fed counterparts; they were not detectable in MCP-1 deficient mice regardless of diet. Plasma concentrations of plasminogen activator inhibitor-1, tumor necrosis factor-α, vascular endothelial growth factor and tissue inhibitor of metalloproteinase-1 were significantly higher in MCP-1 deficient mice compared to wild-type mice. We conclude that adipose-produced MCP-1 contributes to high-fat diet-enhanced metastasis. While MCP-1 deficiency reduces metastasis, the elevation of pro-inflammatory cytokines and angiogenic factors in the absence of MCP-1 may support the metastatic development and growth of LLC in MCP-1 deficient mice.

Contribution of Adipose Tissue to Development of Cancer

Solid tumor growth and metastasis require the interaction of tumor cells with the surrounding tissue, leading to a view of tumors as tissue-level phenomena rather than exclusively cell-intrinsic anomalies. Due to the ubiquitous nature of adipose tissue, many types of solid tumors grow in proximate or direct contact with adipocytes and adipose-associated stromal and vascular components, such as fibroblasts and other connective tissue cells, stem and progenitor cells, endothelial cells, innate and adaptive immune cells, and extracellular signaling and matrix components. Excess adiposity in obesity both increases risk of cancer development and negatively influences prognosis in several cancer types, in part due to interaction with adipose tissue cell populations. Herein, we review the cellular and noncellular constituents of the adipose "organ," and discuss the mechanisms by which these varied microenvironmental components contribute to tumor development, with special emphasis on obesity. Due to the prevalence of breast and prostate cancers in the United States, their close anatomical proximity to adipose tissue depots, and their complex epidemiologic associations with obesity, we particularly highlight research addressing the contribution of adipose tissue to the initiation and progression of these cancer types. Obesity dramatically modifies the adipose tissue microenvironment in numerous ways, including induction of fibrosis and angiogenesis, increased stem cell abundance, and expansion of proinflammatory immune cells. As many of these changes also resemble shifts observed within the tumor microenvironment, proximity to adipose tissue may present a hospitable environment to developing tumors, providing a critical link between adiposity and tumorigenesis. © 2018 American Physiological Society. Compr Physiol 8:237-282, 2018.

Adipose microenvironment promotes triple negative breast cancer cell invasiveness and dissemination by producing CCL5

Growing evidence indicates that adiposity is associated with raised cancer incidence, morbidity and mortality. In a subset of tumors, cancer cell growth and/or metastasis predominantly occur in adipocyte-rich microenvironment. Indeed, adipocytes represent the most abundant cell types surrounding breast cancer cells. We have studied the mechanisms by which peritumoral human adipose tissue contributes to Triple Negative Breast Cancer (TNBC) cell invasiveness and dissemination.

Co-culture with human adipocytes enhanced MDA-MB231 cancer cell invasiveness. Adipocytes cultured in high glucose were 2-fold more active in promoting cell invasion and motility compared to those cultured in low glucose. This effect is induced, at least in part, by the CC-chemokine ligand 5 (CCL5). Indeed, CCL5 inhibition by specific peptides and antibodies reduced adipocyte-induced breast cancer cell migration and invasion. CCL5 immuno-detection in peritumoral adipose tissue of women with TNBC correlated with lymph node (p-value = 0.04) and distant metastases (p-value = 0.001). A positive trend was also observed between CCL5 expression and glycaemia. Finally, Kaplan-Meier curves showed a negative correlation between CCL5 staining in the peritumoral adipose tissue and overall survival of patients (p-value = 0.039).

Thus, inhibition of CCL5 in adipose microenvironment may represent a novel approach for the therapy of highly malignant TNBC.

Esophageal adenocarcinoma microenvironment: Peritumoral adipose tissue effects associated with chemoresistance

Peritumoral microenvironment affects cancer development and chemoresistance, and visceral adipose tissue may play a critical role. We aimed to identify depot‐specific adipose characteristics associated with carcinogenesis and resistance to neoadjuvant therapy in esophageal adenocarcinoma (EAC). We analyzed: (i) the peritumoral adipose tissue of rats following the induction of esophageal carcinogenesis; (ii) the peritumoral and distal (omental) adipose tissue of patients affected by EAC; (iii) adipose‐derived stem cells (ADSC) isolated from healthy patients and treated with conditioned medium (CM), collected from tumoral and adipose tissue of patients with EAC. In peritumoral adipose tissue of rats, CD34, CD31 and vascular endothelial growth factor (VEGF) expression increased progressively during EAC development. In patients with EAC, expression of CD34, CD45, CD90 and nucleostemin (NSTM) was higher in peritumoral than in distal adipose tissue and decreased in the presence of neoadjuvant therapy. Moreover, expression of NSTM, octamer‐binding transcription factor 4 (OCT‐4) and VEGF was higher in peritumoral (but not in distal) adipose tissue of chemoresistant patients. In ADSC, treatment with peritumoral adipose tissue CM increased the adipogenic potential and the expression of CD34, CD90, NSTM and OCT‐4. These effects were similar to those induced by cancer‐derived CM, but were not observed in ADSC treated with distal adipose tissue CM and were partially reduced by a leptin antagonist. Last, ADSC treated with peritumoral CM of chemoresistant patients displayed increased expression of NSTM, OCT‐4, leptin, leptin receptor, alpha‐smooth muscle actin (α‐SMA), CD34 and VEGF. These results suggest that peritumoral adipose tissue may promote, by paracrine signaling, the expression of depot‐specific factors associated with therapeutic resistance.

Microenvironmental regulation of tumour angiogenesis

Tumours display considerable variation in the patterning and properties of angiogenic blood vessels, as well as in their responses to anti-angiogenic therapy. Angiogenic programming of neoplastic tissue is a multidimensional process regulated by cancer cells in concert with a variety of tumour-associated stromal cells and their bioactive products, which encompass cytokines and growth factors, the extracellular matrix and secreted microvesicles. In this Review, we discuss the extrinsic regulation of angiogenesis by the tumour microenvironment, highlighting potential vulnerabilities that could be targeted to improve the applicability and reach of anti-angiogenic cancer therapies.

Plastic Heterogeneity of Innate Lymphoid Cells in Cancer

Innate lymphoid cells (ILCs) fulfill important protective and reparative functions, and have thus been implicated in the maintenance of tissue homeostasis. Dysregulation of their activation is associated with several autoimmune and inflammatory diseases. The current literature on the role of ILCs in cancer is limited and our knowledge is therefore incomplete. Indeed, ILCs have been separately associated with tumor-promoting as well as tumor-suppressing activities, raising the need to understand the mechanisms by which these cells regulate tumor growth and progression toward a rational design of therapeutic approaches. We focus here on the heterogeneity of ILCs and discuss currently known mechanisms of their plasticity.

Obesity and melanoma: could fat be fueling malignancy?

Over the last decade, it has become increasingly clear that adipose tissue, and particularly adipocytes, contributes to tumor progression. Obesity, an ever-increasing worldwide phenomenon, exacerbates this effect. The influence of obesity on melanoma remains poorly studied, although recent data do underline an association between the two diseases in both humans and murine models. Herein, we review the impact of obesity on melanoma incidence and progression and discuss the underlying mechanisms known to be involved. Adipose tissue favors the proliferation and aggressiveness of melanoma cells through a direct dialog, mediated by soluble factors and by exosomes, and through remodeling of the tumor microenvironment. This knowledge could, in the future, help to design new personalized therapeutic options for obese melanoma patients.

The ominous triad of adipose tissue dysfunction: inflammation, fibrosis, and impaired angiogenesis

There are three dominant contributors to the pathogenesis of dysfunctional adipose tissue (AT) in obesity: unresolved inflammation, inappropriate extracellular matrix (ECM) remodeling and insufficient angiogenic potential. The interactions of these processes during AT expansion reflect both a linear progression as well as feed-forward mechanisms. For example, both inflammation and inadequate angiogenic remodeling can drive fibrosis, which can in turn promote migration of immune cells into adipose depots and impede further angiogenesis. Therefore, the relationship between the members of this triad is complex but important for our understanding of the pathogenesis of obesity. Here we untangle some of these intricacies to highlight the contributions of inflammation, angiogenesis, and the ECM to both "healthy" and "unhealthy" AT expansion.

Natural products against cancer angiogenesis

The process of angiogenesis is quite well-known nowadays. Some medicines and extracts affecting this process are already used routinely in supporting the conventional treatment of many diseases that are considered angiogenic such as cancer. However, we must be aware that the area of currently used drugs of this type is much narrower than the theoretical possibilities existing in therapeutic angiogenesis. Plant substances are a large and diverse group of compounds that are found naturally in fruits, vegetables, spices, and medicinal plants. They also have different anticancer properties. The aim of this literature review article is to present the current state of knowledge concerning the molecular targets of tumor angiogenesis and the active substances (polyphenols, alkaloids, phytohormones, carbohydrates, and terpenes) derived from natural sources, whose activity against cancer angiogenesis has been confirmed.

Accumulation of CD11c+CD163+ Adipose Tissue Macrophages through Upregulation of Intracellular 11β-HSD1 in Human Obesity

Adipose tissue (AT) macrophages (ATMs) are key players for regulation of AT homeostasis and obesity-related metabolic disorders. However, the phenotypes of human ATMs and regulatory mechanisms of their polarization have not been clearly described. In this study, we investigated human ATMs in both abdominal visceral AT and s.c. AT and proposed an 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1)-glucocorticoid receptor regulatory axis that might dictate M1/M2 polarization in ATMs. The accumulation of CD11c⁺CD163⁺ ATMs in both visceral AT and s.c. AT of obese individuals was confirmed at the cellular level and was found to be clearly correlated with body mass index and production of reactive oxygen species. Using our in vitro system where human peripheral blood monocytes (hPBMs) were cocultured with Simpson-Golabi-Behmel syndrome adipocytes, M1/M2 polarization was found to be dependent on 11β-HSD1, an intracellular glucocorticoid reactivating enzyme. Exposure of hPBMs to cortisol-induced expression of CD163 and RU-486, a glucocorticoid receptor antagonist, significantly abrogated CD163 expression through coculture of mature adipocytes with hPBMs. Moreover, 11β-HSD1 was expressed in crown ATMs in obese AT. Importantly, conditioned medium from coculture of adipocytes with hPBMs enhanced proliferation of human breast cancer MCF7 and MDA-MB-231 cells. In summary, the phenotypic switch of ATMs from M2 to mixed M1/M2 phenotype occurred through differentiation of adipocytes in obese individuals, and upregulation of intracellular 11β-HSD1 might play a role in the process.

Peritumoral adipose tissue as a source of inflammatory and angiogenic factors in colorectal cancer

PURPOSE

Obesity is a risk factor for the development of human colorectal cancer (CC). The aim of this work is to report the inflammatory and angiogenic scenario in lean (BMI < 25 kg/m2) and obese (BMI > 30 kg/m2) patients with and without CC and to assess the role of peritumoral adipose tissue in CC-induced inflammation.

MATERIAL AND METHODS

Patients were divided in four experimental groups: obese patients with CC (OB-CC), lean patients with CC (LEAN-CC), obese patients without CC (OB), and lean patients without CC (LEAN).

RESULTS

Plasma levels of pro-inflammatory cytokines (interleukin (IL)-6, IL-4, IL-8) and granulocyte-macrophage colony-stimulating factor (GM-CSF) were increased in OB-CC patients. Peritumoral adipose tissue (TF) explants and cultured mature adipocytes secreted higher amounts of nitrites and nitrates than did control and non-tumoral (NTF) adipose tissue both alone and in response to lipopolysaccharide (LPS). Nitrite and nitrate secretion was also increased in TF explants from OB-CC patients compared with that from LEAN-CC patients. Gene expression of adiponectin, tumor necrosis factor alpha (TNF-α), insulin-like growth factor type I (IGF-I), cyclooxygenase-2 (COX-2), and peroxisome proliferator-activated receptor γ (PPAR-γ) was increased in TF explants from CC patients. LPS increased the gene expression of IL-6, IL-10, TNF-α, vascular endothelial growth factor (VEGF), and COX-2 in OB and in TF explants from OB-CC patients. COX-2 and PPAR-γ inhibition further increased LPS-induced release of nitrites and nitrates in TF explants and adipocytes from OB-CC patients.

CONCLUSIONS

In conclusion, OB-CC patients have increased plasma levels of pro-inflammatory and angiogenic factors. TF from OB-CC patients shows an increased secretion of inflammatory markers compared with both TF from LEAN-CC and non-tumoral adipose tissue (AT) through a COX-2- and PPAR-γ-independent mechanism.

Effect of Adipocyte Secretome in Melanoma Progression and Vasculogenic Mimicry

Obesity, favored by the modern lifestyle, acquired epidemic proportions nowadays. Obesity has been associated with various major causes of death and morbidity including malignant neoplasms. This increased prevalence has been accompanied by a worldwide increase in cutaneous melanoma incidence rates during the last decades. Obesity involvement in melanoma aetiology has been recognized, but the implicated mechanisms remain unclear. In the present study, we address this relationship and investigate the influence of adipocytes secretome on B16-F10 and MeWo melanoma cell lines. Using the 3T3-L1 adipocyte cell line, as well as ex vivo subcutaneous (SAT) and visceral (VAT) adipose tissue conditioned medium, we were able to show that adipocyte-released factors play a dual role in increasing melanoma cell overall survival, both by enhancing proliferation and decreasing apoptosis. B16-F10 cell migration and cell-cell and cell-matrix adhesion capacity were predominantly enhanced in the presence of SAT and VAT released factors. Melanocytes morphology and melanin content were also altered by exposure to adipocyte conditioned medium disclosing a more dedifferentiated phenotype of melanocytes. In addition, exposure to adipocyte-secreted molecules induced melanocytes to rearrange, on 3D cultures, into vessel-like structures, and generate characteristic vasculogenic mimicry patterns. These findings are corroborated by the released factors profile of 3T3-L1, SAT, and VAT assessed by microarrays, and led us to highlight the mechanisms by which adipose secretome from sub-cutaneous or visceral depots promote melanoma progression. J. Cell. Biochem. 117: 1697-1706, 2016. © 2015 Wiley Periodicals, Inc.

High-Fat, High-Calorie Diet Enhances Mammary Carcinogenesis and Local Inflammation in MMTV-PyMT Mouse Model of Breast Cancer

Epidemiological studies provide strong evidence that obesity and the associated adipose tissue inflammation are risk factors for breast cancer; however, the molecular mechanisms are poorly understood. We evaluated the effect of a high-fat/high-calorie diet on mammary carcinogenesis in the immunocompetent MMTV-PyMT murine model. Four-week old female mice (20/group) were randomized to receive either a high-fat (HF; 60% kcal as fat) or a low-fat (LF; 16% kcal) diet for eight weeks. Body weights were determined, and tumor volumes measured by ultrasound, each week. At necropsy, the tumors and abdominal visceral fat were weighed and plasma collected. The primary mammary tumors, adjacent mammary fat, and lungs were preserved for histological and immunohistochemical examination and quantification of infiltrating macrophages, crown-like structure (CLS) formation, and microvessel density. The body weight gains, visceral fat weights, the primary mammary tumor growth rates and terminal weights, were all significantly greater in the HF-fed mice. Adipose tissue inflammation in the HF group was indicated by hepatic steatosis, pronounced macrophage infiltration and CLS formation, and elevations in plasma monocyte chemoattractant protein-1 (MCP-1), leptin and proinflammatory cytokine concentrations. HF intake was also associated with higher tumor-associated microvascular density and the proangiogenic factor MCP-1. This study provides preclinical evidence in a spontaneous model of breast cancer that mammary adipose tissue inflammation induced by diet, enhances the recruitment of macrophages and increases tumor vascular density suggesting a role for obesity in creating a microenvironment favorable for angiogenesis in the progression of breast cancer.

Anti-metastatic outcome of isoform-specific prolactin receptor targeting in breast cancer

Controversy exists concerning the role of the long prolactin receptor (PRLR) in the progression of breast cancer. By targeting pre-mRNA splicing, we succeeded in knocking down only the long PRLR in vivo, leaving the short forms unaffected. Using two orthotopic and highly-metastatic models of breast cancer, one of which was syngeneic (mouse 4T1) to allow assessment of tumor-immune interactions and one of which was endocrinologically humanized (human BT-474) to activate human PRLRs, we examined the effect of long PRLR knockdown on disease progression. In both models, knockdown dramatically inhibited metastatic spread to the lungs and liver and resulted in increased central death in the primary tumor. In the syngeneic model, immune infiltrates in metastatic sites were changed from innate inflammatory cells to lymphocytes, with an increase in the incidence of tumor-specific cytotoxic T cells. Long PRLR knockdown in three-dimensional culture induced apoptosis of tumor-initiating/cancer stem cells (death of 95% of cells displaying stem cell markers in 15 days). We conclude that the long PRLR plays an important role in breast cancer metastasis.

Adipose tissue macrophage polarization by intermittent hypoxia in a mouse model of OSA: effect of tumor microenvironment

Intermittent hypoxia (IH)-induces alterations in tumor-associated macrophages (TAMs) that are associated with adverse cancer outcomes, as reported in patients suffering from sleep apnea. Adipose tissues (AT) and bone-marrow (BM)-derived cells are the inferred sources of macrophages infiltrating malignant tumors. Here, the sources of TAMs and the phenotypic changes induced by IH in the ipsilateral and contralateral AT were investigated by using a syngeneic murine solid tumor model (TC1). C57/B6 male mice were exposed to either IH or room air (RA) for 6 weeks, with TC1 cells being inoculated in the 2nd week. Macrophage content, phenotype and tissue origin were assessed in tumors, and ipsilateral and contralateral AT. IH induced a ~2.2-fold increase in TAM tumor infiltration. However, differential responses in the tumor ipsilateral and contralateral AT emerged: IH increased infiltration of preferentially M1 macrophages in contralateral AT, while reductions in macrophages emerged in ipsilateral AT and primarily consisted of the M2 phenotype. These changes were accompanied by reciprocal increases in resident and BM-derived TAMs in the tumor. IH-induced phenotypic alterations in AT macrophages surrounding the tumor and their increased infiltration within the tumor may contribute to the accelerated tumor progression associated with IH.

Fitness, nutrition and the molecular basis of chronic disease

The onset of chronic disease is often the prelude to the subsequent physiological and mental twilight in the aging population of modern society. While rates of obesity, specific types of cancer and cardiovascular disorders seem to be on the rise in this group, many new therapies have addressed diseases that have been largely untreatable in the past. Alzheimer's disease has also recently come to the forefront of ongoing maladies most typically associated with an aging population. Ironically, though, many people seem to be living longer than expected. Recent biochemical, nutritional and genomic approaches have been able to elucidate some of the complex mechanisms, which lead to chronic diseases associated with an aging population such as Alzheimer's, metabolic syndrome, tumor metastasis and cardiovascular disease. These diseases and their sequalae seem to be related in many respects, with the common culprit being the inflammatory environment created by the presence of excess fat - particularly within the vascular network. Although a substantial effort has been focused on the development of new-line therapeutics to address these issues, nutrition and overall fitness and their effects on stalling or potentially reversing the advent of these diseases has not been fully embraced in the research arena. This review discusses the role of the inflammatory environment in the development of chronic diseases in the aging population and also proposes a common pathology. The benefits that improvements and dedication in nutrition and fitness approaches may offer at the molecular level are also discussed.