The fat and the bad: Mature adipocytes, key actors in tumor progression and resistance

Clinical Significance of Peritumoral Adipose Tissue PET/CT Imaging Features for Predicting Axillary Lymph Node Metastasis in Patients with Breast Cancer

We investigated whether textural parameters of peritumoral breast adipose tissue (AT) based on F-18 fluorodeoxyglucose (FDG) PET/CT could predict axillary lymph node metastasis in patients with breast cancer. A total of 326 breast cancer patients with preoperative FDG PET/CT were retrospectively enrolled. PET/CT images were visually assessed and the maximum FDG uptake of axillary lymph nodes (LN SUVmax) was measured. From peritumoral breast AT, 38 textural features of PET imaging were extracted. The diagnostic ability of PET based on visual analysis, LN SUVmax, and textural features of peritumoral breast AT for predicting axillary lymph node metastasis were assessed using the area under the receiver operating characteristic curve (AUC) values. Among the 38 peritumoral breast AT textural features, grey-level co-occurrence matrix (GLCM) entropy showed the highest AUC value (0.830) for predicting axillary lymph node metastasis. The value of GLCM entropy was higher than that of visual analysis (0.739; p < 0.05) and the AUC value was comparable to that of LN SUVmax (0.793; p > 0.05). In the subgroup analysis of patients with negative findings on visual analysis, GLCM entropy still showed a high diagnostic ability (AUC: 0.759) in predicting lymph node metastasis. The findings suggest a potential diagnostic role of PET/CT imaging features of peritumoral breast AT in predicting axillary lymph node metastasis in patients with breast cancer.

Insuline-Like Growth Factor-2 (IGF2) and Hepatocyte Growth Factor (HGF) Promote Lymphomagenesis in p53-null Mice in Tissue-specific and Estrogen-signaling Dependent Manners

Background: Trp53^-/- mice are prone to develop lymphomas at old ages. Factors promoting this tumorigenesis are unknown. Here, we showed human ovulatory follicular fluid (FF) largely promotes lymphomagenesis in Trp53^-/- mice at earlier ages. Meanwhile, we clarified that IGF2 and HGF are important cell transforming factors within FF. Methods: To induce tumor formation, 5% FFs, 100 ng/ml IGF2, 20 ng/ml HGF, or both IGF2 and HGF in a volume of 200 µl PBS, was injected into 8-wk-old female Trp53 ^-/- mice at the mammary fat pad. The injection was repeated weekly for up to 7 weeks or extending to 13 weeks to observe the accumulative incidence of lymphomagenesis. Immunohistochemistry staining and gene rearrangement analysis were used to identify the tumor type. Results: By injecting FF into the mammary fat pad weekly, lymphomas developed in 8/16 (50%) of mice by seven weeks. We identified IGF2 and HGF in FF is largely responsible for this activity. The same weekly injection of IGF2, HGF, and their combination induced lymphomas in 4/11 (36%), 3/8 (38%), and 6/9 (67%) mice, respectively. Interestingly, tumorigenesis was induced only when those were injected into the adipose tissues in the mammary gland, but not when injected into non-adipose sites. We also found this tumor-promoting activity is estradiol (E2)-dependent and relies on estrogen receptor (ER) α expression in the adipose stroma. No tumor or only tiny tumor was yielded when the ovaries were resected or when ER is antagonized. Finally, an extension of the weekly FF-injection to 13 weeks did not further increase the lymphomagenesis rate, suggesting an effect on pre-initiated cancer cells. Conclusions: Taken together, the study disclosed a robust tumor-promoting effect of IGF2 and HGF in the p53 loss-initiated lymphomagenesis depending on an adipose microenvironment in the presence of E2. In light of the clarity of this spontaneous tumor promotion model, we provide a new tool for studying p53-mediated lymphomagenesis and suggest that, as a chemoprevention test, this is a practical model to perform.

Characterization of inflammatory changes in the breast cancer associated adipose tissue and comparison to the unaffected contralateral breast

BACKGROUND

Adipose tissue has emerged as an important window into cancer pathophysiology, revealing potential targets for novel therapeutic interventions. The goal of this study was to compare the breast adipose tissue (BrAT) immune milieu surrounding breast carcinoma and contralateral unaffected breast tissue obtained from the same patient.

MATERIALS AND METHODS

Patients undergoing bilateral mastectomy for unilateral breast cancer were enrolled for bilateral BrAT collection at the time of operation. After BrAT was processed, adipocyte and stromal vascular fraction (SVF) gene expression was quantified by PCR. SVF cells were also processed for flow cytometric immune cell characterization.

RESULTS

Twelve patients underwent bilateral mastectomy for unilateral ductal carcinoma. BrAT adipocyte CXCL2 gene expression trended higher in the tumor-affected breast as compared to the unaffected breast. Macrophage MCP-1 and PPARγ gene expression also tended to be higher in the tumor-affected breasts. T cell gene expression of FOXP3 (p = 0.0370) were significantly greater in tumor-affected breasts than unaffected breasts. Affected BrAT contained higher numbers of Th2 CD4⁺ cells (p = 0.0165) and eosinophils (p = 0.0095) while trending towards increased macrophage and lower Th1 CD4⁺ cells infiltration than tumor-affected BrAT.

CONCLUSION

This preliminary study aimed to identify the immunologic environment present within BrAT and is the first to directly compare this in individual patients' tumor-associated and unaffected BrAT. These findings suggest that cancer-affected BrAT had increased levels of T cell specific FOXP3 and higher levels of anti-inflammatory/regulatory cells compared to the contralateral BrAT.

Adipokine Apelin/APJ Pathway Promotes Peritoneal Dissemination of Ovarian Cancer Cells by Regulating Lipid Metabolism

Adipose tissue, which can provide adipokines and nutrients to tumors, plays a key role in promoting ovarian cancer metastatic lesions in peritoneal cavity. The adipokine apelin promotes ovarian cancer metastasis and progression through its receptor APJ, which regulates cell proliferation, energy metabolism, and angiogenesis. The objective of this study was to investigate the functional role and mechanisms of the apelin-APJ pathway in ovarian cancer metastasis, especially in context of tumor cell-adipocyte interactions. When co-cultured in the conditioned media (AdipoCM) derived from 3T3-L1 adipocytes, which express and secrete high apelin, human ovarian cancer cells with high APJ expression showed significant increases in migration and invasion in vitro. We also found that cells expressing high levels of APJ had increased cell adhesion to omentum ex vivo, and preferentially "home-in" on the omentum in vivo. These apelin-induced pro-metastatic effects were reversed by APJ antagonist F13A in a dose-dependent manner. Apelin-APJ activation increased lipid droplet accumulation in ovarian cancer cells, which was further intensified in the presence of AdipoCM and reversed by F13A or APJ knockdown. Mechanistically, this increased lipid uptake was mediated by CD36 upregulation via APJ-STAT3 activation, and the lipids were utilized in promoting fatty acid oxidation via activation of AMPK-CPT1a axis. Together, our studies demonstrate that adipocyte-derived apelin activates APJ-expressing tumor cells in a paracrine manner, promoting lipid uptake and utilization and providing energy for ovarian cancer cell survival at the metastatic sites. Hence, the apelin-APJ pathway presents a novel therapeutic target to curb ovarian cancer metastasis. IMPLICATIONS: Targeting the APJ pathway in high-grade serous ovarian carcinoma is a novel strategy to inhibit peritoneal metastasis.

Construction and Validation of a Universal Applicable Prognostic Signature for Gastric Cancer Based on Seven Immune-Related Gene Correlated With Tumor Associated Macrophages

Background

Tumor-associated macrophages (TAMs) play a critical role in the progression of malignant tumors, but the detailed mechanism of TAMs in gastric cancer (GC) is still not fully explored.

Methods

We identified differentially expressed immune-related genes (DEIRGs) between GC samples with high and low macrophage infiltration in The Cancer Genome Atlas datasets. A risk score was constructed based on univariate Cox analysis and Lasso penalized Cox regression analysis in the TCGA cohort (n=341). The optimal cutoff determined by the 5-year time-dependent receiver operating characteristic (ROC) curve was considered to classify patients into groups with high and low risk. We conducted external validation of the prognostic signature in four independent cohorts (GSE84437, n=431; GSE62254, n=300; GSE15459, n=191; and GSE26901, n=109) from the Gene Expression Omnibus (GEO) database.

Results

The signature consisting of 7 genes (FGF1, GRP, AVPR1A, APOD, PDGFRL, CXCR4, and CSF1R) showed good performance in predicting overall survival (OS) in the 5 independent cohorts. The risk score presented an obviously positive correlation with macrophage abundance (cor=0.7, p<0.001). A significant difference was found between the high- and low-risk groups regarding the overall survival of GC patients. The high-risk group exhibited a higher infiltration level of M2 macrophages estimated by the CIBERSORT algorithm. In the five independent cohorts, the risk score was highly positively correlated with the stromal cell score, suggesting that we can also evaluate the infiltration of stromal cells in the tumor microenvironment according to the risk score.

Conclusion

Our study developed and validated a general applicable prognostic model for GC from the perspective of TAMs, which may help to improve the precise treatment strategy of GC.

The Role of Tumor-Stroma Interactions in Drug Resistance Within Tumor Microenvironment

Cancer cells resistance to various therapies remains to be a key challenge nowadays. For a long time, scientists focused on tumor cells themselves for the mechanisms of acquired drug resistance. However, recent evidence showed that tumor microenvironment (TME) is essential for regulating immune escape, drug resistance, progression and metastasis of malignant cells. Reciprocal interactions between cancer cells and non-malignant cells within this milieu often reshape the TME and promote drug resistance. Therefore, advanced knowledge about these sophisticated interactions is significant for the design of effective therapeutic approaches. In this review, we highlight cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), T-regulatory lymphocytes (Tregs), mesenchymal stem cells (MSCs), cancer-associated adipocytes (CAAs), and tumor endothelial cells (TECs) existing in TME, as well as their multiple cross-talk with tumor cells, which eventually endows tumor cells with therapeutic resistance.

C(3)1-TAg in C57BL/6 J background as a model to study mammary tumor development

Diagnosis and prognosis of breast cancer is based on disease staging identified through histopathological and molecular biology techniques. Animal models are used to gain mechanistic insights into the development of breast cancer. C(3)1-TAg is a genetically engineered mouse model that develops mammary cancer. However, carcinogenesis caused by this transgene was characterized in the Friend Virus B (FVB) background. As most genetic studies are done in mice with C57BL/6 J background, we aimed to define the histological alterations in C3(1)-TAg C57BL/6 J animals. Our results showed that C3(1)-TAg animals with C57BL/6 J background develop solid-basaloid adenoid cystic carcinomas with increased fibrosis, decreased area of adipocytes, and a high proliferative index, which are triple-negative for progesterone, estrogen, and human epidermal growth factor receptor 2 (HER2) receptors. Our results also revealed that tumor development is slower in the C57BL/6 J background when compared with the FVB strain, providing a better model to study the different stages in breast cancer progression.

Lipid and glucose metabolism in white adipocytes: pathways, dysfunction and therapeutics

In mammals, the white adipocyte is a cell type that is specialized for storage of energy (in the form of triacylglycerols) and for energy mobilization (as fatty acids). White adipocyte metabolism confers an essential role to adipose tissue in whole-body homeostasis. Dysfunction in white adipocyte metabolism is a cardinal event in the development of insulin resistance and associated disorders. This Review focuses on our current understanding of lipid and glucose metabolic pathways in the white adipocyte. We survey recent advances in humans on the importance of adipocyte hypertrophy and on the in vivo turnover of adipocytes and stored lipids. At the molecular level, the identification of novel regulators and of the interplay between metabolic pathways explains the fine-tuning between the anabolic and catabolic fates of fatty acids and glucose in different physiological states. We also examine the metabolic alterations involved in the genesis of obesity-associated metabolic disorders, lipodystrophic states, cancers and cancer-associated cachexia. New challenges include defining the heterogeneity of white adipocytes in different anatomical locations throughout the lifespan and investigating the importance of rhythmic processes. Targeting white fat metabolism offers opportunities for improved patient stratification and a wide, yet unexploited, range of therapeutic opportunities.

Label-Free Deep Profiling of the Tumor Microenvironment

Label-free nonlinear microscopy enables nonperturbative visualization of structural and metabolic contrast within living cells in their native tissue microenvironment. Here a computational pipeline was developed to provide a quantitative view of the microenvironmental architecture within cancerous tissue from label-free nonlinear microscopy images. To enable single-cell and single-extracellular vesicle (EV) analysis, individual cells, including tumor cells and various types of stromal cells, and EVs were segmented by a multiclass pixelwise segmentation neural network and subsequently analyzed for their metabolic status and molecular structure in the context of the local cellular neighborhood. By comparing cancer tissue with normal tissue, extensive tissue reorganization and formation of a patterned cell-EV neighborhood was observed in the tumor microenvironment. The proposed analytic pipeline is expected to be useful in a wide range of biomedical tasks that benefit from single-cell, single-EV, and cell-to-EV analysis. SIGNIFICANCE: The proposed computational framework allows label-free microscopic analysis that quantifies the complexity and heterogeneity of the tumor microenvironment and opens possibilities for better characterization and utilization of the evolving cancer landscape.

Macrophage inhibitory cytokine-1 induced by a high-fat diet promotes prostate cancer progression by stimulating tumor-promoting cytokine production from tumor stromal cells

Background

Recent studies have indicated that a high‐fat diet (HFD) and/or HFD‐induced obesity may influence prostate cancer (PCa) progression, but the role of HFD in PCa microenvironment is unclear. This study aimed to delineate the molecular mechanisms of PCa progression under HFD milieus and define the stromal microenvironment focusing on macrophage inhibitory cytokine‐1 (MIC‐1) activation.

Methods

We investigated the effects of HFD on PCa stromal microenvironment and MIC‐1 signaling activation using PC‐3M‐luc‐C6 PCa model mice fed with HFD or control diet. Further, we explored the effect of periprostatic adipocytes derived from primary PCa patients on activation and cytokine secretion of prostate stromal fibroblasts. Expression patterns and roles of MIC‐1 signaling on human PCa stroma activation and progression were also investigated.

Results

HFD stimulated PCa cell growth and invasion as a result of upregulated MIC‐1 signaling and subsequently increased the secretion of interleukin (IL)‐8 and IL‐6 from prostate stromal fibroblasts in PC‐3M‐luc‐C6 PCa mouse model. In addition, periprostatic adipocytes directly stimulated MIC‐1 production from PC‐3 cells and IL‐8 secretion in prostate stromal fibroblasts through the upregulation of adipose lipolysis and free fatty acid release. The increased serum MIC‐1 was significantly correlated with human PCa stroma activation, high serum IL‐8, IL‐6, and lipase activity, advanced PCa progression, and high body mass index of the patients. Glial‐derived neurotrophic factor receptor α‐like (GFRAL), a specific receptor of MIC‐1, was highly expressed in both cytoplasm and membrane of PCa cells and surrounding stromal fibroblasts, and the expression level was decreased by androgen deprivation therapy and chemotherapy.

Conclusion

HFD‐mediated activation of the PCa stromal microenvironment through metabolically upregulated MIC‐1 signaling by increased available free fatty acids may be a critical mechanism of HFD and/or obesity‐induced PCa progression.

Exosomal Non-Coding RNAs: Regulatory and Therapeutic Target of Hepatocellular Carcinoma

Exosomes are small extracellular vesicles secreted by most somatic cells, which can carry a variety of biologically active substances to participate in intercellular communication and regulate the pathophysiological process of recipient cells. Recent studies have confirmed that non-coding RNAs (ncRNAs) carried by tumor cell/non-tumor cell-derived exosomes have the function of regulating the cancerous derivation of target cells and remodeling the tumor microenvironment (TME). In addition, due to the unique low immunogenicity and high stability, exosomes can be used as natural vehicles for the delivery of therapeutic ncRNAs in vivo. This article aims to review the potential regulatory mechanism and the therapeutic value of exosomal ncRNAs in hepatocellular carcinoma (HCC), in order to provide promising targets for early diagnosis and precise therapy of HCC.

Redox profile of breast tumor and associated adipose tissue in premenopausal women - Interplay between obesity and malignancy

One of the underlying mechanisms that could link breast cancer and obesity is shifted redox homeostasis in the tumor microenvironment. To reveal the relationship between the malignant phenotype and obesity, we compared redox profiles of breast tumor and tumor-associated adipose tissue from premenopausal women: normal-weight with benign tumors, overweight/obese with benign tumors, normal-weight with malignant tumors, and overweight/obese with malignant tumors. Namely, we examined the protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2), protein expression and activity of main antioxidant defense (AD) enzymes: copper, zinc- and manganese superoxide dismutase, catalase, and glutathione peroxidase, as well as the level of 4-hydroxy-2-nonenal (4-HNE) modified proteins. Higher protein expression and activity of AD enzymes were found in malignant tumor tissue than benign tumor tissue, irrespective of obesity. Nevertheless, malignant tumor tissue of overweight/obese women was characterized by higher protein expression of Nrf2 and weaker immunopositivity for 4-HNE modified proteins. In malignant tumor-associated adipose tissue, the redox profile was clearly related to obesity. Higher Nrf2 protein expression and higher AD enzyme levels were observed in normal-weight women, while stronger immunopositivity for 4-HNE modified proteins was found in overweight/obese women. The results suggest that the complex interplay between obesity and malignancy involves redox-sensitive pathways in breast tumor and tumor-associated adipose tissue.

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In malignant breast tumor tissue, antioxidant defense enzyme levels are not related to obesity.

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In malignant tumor-associated adipose tissue, redox profile is related to obesity.

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Nrf2 contributes to the “activated” phenotype of adipose tissue in malignancy.

Adipocyte-derived extracellular vesicles in health and diseases: Nano-packages with vast biological properties

As the largest human energy reservoir, adipocytes drive an intense dialog with other cells/organs throughout the body to regulate the size of adipose tissue and to communicate with other metabolic tissues and the brain to regulate energy supply. Adipokines have long been described as mediators of this crosstalk, participating in obesity‐associated complications. Recently, adipocyte‐derived extracellular vesicles (Ad‐EVs) have emerged as new key actors in this communication due to their powerful capacity to convey complex messages between cells. Ad‐EVs convey specific subpopulations of RNA, proteins, and lipids from their parental cells, and can transfer these cargoes into various recipient cells, modulating their metabolism and cell cycle. In healthy individuals, Ad‐EVs actively participate in adipose tissue remodeling to compensate energy supply variations by exchanging information between adipocytes or stroma‐vascular cells, including immune cells. Besides this, recent evidence points out that Ad‐EV secretion and composition from dysfunctional adipocytes are strongly impacted within adipose tissue where they modulate local intercellular communication, contributing to inflammation, fibrosis, abnormal angiogenesis, and at distance with other cells/tissues intrinsically linked to fat (muscle, hepatocytes and even cancer cells). Additionally, some data even suggests that Ad‐EVs might have a systemic action. In this review, we will describe the particular properties of Ad‐EVs and their involvement in health and diseases, with a particular focus on metabolic and cardiovascular diseases as well as cancer.

The Tumor Promotional Role of Adipocytes in the Breast Cancer Microenvironment and Macroenvironment

The role of the adipocyte in the tumor microenvironment has received significant attention as a critical mediator of the obesity-cancer relationship. Current estimates indicate that 650 million adults have obesity, and thirteen cancers, including breast cancer, are estimated to be associated with obesity. Even in people with a normal body mass index, adipocytes are key players in breast cancer progression because of the proximity of tumors to mammary adipose tissue. Outside the breast microenvironment, adipocytes influence metabolic and immune function and produce numerous signaling molecules, all of which affect breast cancer development and progression. The current epidemiologic data linking obesity, and importantly adipose tissue, to breast cancer risk and prognosis, focusing on metabolic health, weight gain, and adipose distribution as underlying drivers of obesity-associated breast cancer is presented here. Bioactive factors produced by adipocytes, both normal and cancer associated, such as cytokines, growth factors, and metabolites, and the potential mechanisms through which adipocytes influence different breast cancer subtypes are highlighted.

The Chemokine Receptor CCR3 Is Potentially Involved in the Homing of Prostate Cancer Cells to Bone: Implication of Bone-Marrow Adipocytes

Bone metastasis remains the most frequent and the deadliest complication of prostate cancer (PCa). Mechanisms leading to the homing of tumor cells to bone remain poorly characterized. Role of chemokines in providing navigational cues to migrating cancer cells bearing specific receptors is well established. Bone is an adipocyte-rich organ since 50 to 70% of the adult bone marrow (BM) volume comprise bone marrow adipocytes (BM-Ads), which are likely to produce chemokines within the bone microenvironment. Using in vitro migration assays, we demonstrated that soluble factors released by human primary BM-Ads are able to support the directed migration of PCa cells in a CCR3-dependent manner. In addition, we showed that CCL7, a chemokine previously involved in the CCR3-dependent migration of PCa cells outside of the prostate gland, is released by human BM-Ads. These effects are amplified by obesity and ageing, two clinical conditions known to promote aggressive and metastatic PCa. In human tumors, we found an enrichment of CCR3 in bone metastasis vs. primary tumors at mRNA levels using Oncomine microarray database. In addition, immunohistochemistry experiments demonstrated overexpression of CCR3 in bone versus visceral metastases. These results underline the potential importance of BM-Ads in the bone metastatic process and imply a CCR3/CCL7 axis whose pharmacological interest needs to be evaluated.

Molecular insights into the interplay between adiposity, breast cancer and bone metastasis

Cancer is a complex disease, with various pre-existing health ailments enhancing its pathology. In cancer, the extracellular environment contains various intrinsic physiological factors whose levels are altered with aging and pre-existing conditions. In obesity, the tumor microenvironment and metastases are enriched with factors that are both derived locally, and from other physiological compartments. Similarly, in obesity, the cancer cell environment both at the site of origin and at the secondary site i.e., metastatic niche, contains significantly more phenotypically-altered adipocytes than that of un-obese cancer patients. Indeed, obesity has been linked with cancer progression, metastasis, and therapy resistance. Adipocytes not only interact with tumor cells, but also with adjacent stromal cells at primary and metastatic sites. This review emphasizes the importance of bidirectional interactions between adipocytes and breast tumor cells in breast cancer progression and its bone metastases. This paper not only chronicles the role of various adipocyte-derived factors in tumor growth, but also describes the significance of adipocyte-derived bone metastatic factors in the development of bone metastasis of breast cancer. It provides a molecular view of the interplay between the adipocytes and tumor cells involved in breast cancer bone metastasis. However, more research is needed to determine if targeting cancer-associated adipocytes holds promise as a potential therapeutic approach for breast cancer bone metastasis treatment. Interplay between adipocytes and breast cancer cells at primary cancer site and metastatic bone microenvironment. AMSC Adipose-derived mesenchymal stem cell, CAA Cancer associated adipocytes, CAF Cancer associated fibroblast, BMSC Bone marrow derived mesenchymal stem cell, BMA Bone marrow adipocyte.

HGF/c-Met Signalling in the Tumor Microenvironment

Recently, it has become clearer that tumor plasticity increases the chance that cancer cells could acquire new mechanisms to escape immune surveillance, become resistant to conventional drugs, and spread to distant sites.Effectively, tumor plasticity drives adaptive response of cancer cells to hypoxia and nutrient deprivation leading to stimulation of neoangionesis or tumor escape. Therefore, tumor plasticity is believed to be a great contributor in recurrence and metastatic dissemination of cancer cells. Importantly, it could be an Achilles' heel of cancer if we could identify molecular mechanisms dictating this phenotype.The reactivation of stem-like signalling pathways is considered a great determinant of tumor plasticity; in addition, a key role has been also attributed to tumor microenvironment (TME). Indeed, it has been proved that cancer cells interact with different cells in the surrounding extracellular matrix (ECM). Interestingly, well-established communication represents a potential allied in maintenance of a plastic phenotype in cancer cells supporting tumor growth and spread. An important signalling pathway mediating cancer cell-TME crosstalk is represented by the HGF/c-Met signalling.Here, we review the role of the HGF/c-Met signalling in tumor-stroma crosstalk focusing on novel findings underlying its role in tumor plasticity, immune escape, and development of adaptive mechanisms.

The Adipose Tissue at the Crosstalk Between EDCs and Cancer Development

Obesity is a major public health concern at the origin of many pathologies, including cancers. Among them, the incidence of gastro-intestinal tract cancers is significantly increased, as well as the one of hormone-dependent cancers. The metabolic changes caused by overweight mainly with the development of adipose tissue (AT), insulin resistance and chronic inflammation induce hormonal and/or growth factor imbalances, which impact cell proliferation and differentiation. AT is now considered as the main internal source of endocrine disrupting chemicals (EDCs) representing a low level systemic chronic exposure. Some EDCs are non-metabolizable and can accumulate in AT for a long time. We are chronically exposed to low doses of EDCs able to interfere with the endocrine metabolism of the body. Importantly, several EDCs have been involved in the genesis of obesity affecting profoundly the physiology of AT. In parallel, EDCs have been implicated in the development of cancers, in particular hormone-dependent cancers (prostate, testis, breast, endometrium, thyroid). While it is now well established that AT secretes adipocytokines that promote tumor progression, it is less clear whether they can initiate cancer. Therefore, it is important to better understand the effects of EDCs, and to investigate the buffering effect of AT in the context of progression but also initiation of cancer cells using adequate models recommended to uncover and validate these mechanisms for humans. We will review and argument here the potential role of AT as a crosstalk between EDCs and hormone-dependent cancer development, and how to assess it.

Lactate Metabolism in Breast Cancer Microenvironment: Contribution Focused on Associated Adipose Tissue and Obesity

Metabolic reprogramming that favors high glycolytic flux with lactate production in normoxia is among cancer hallmarks. Lactate is an essential oncometabolite regulating cellular redox homeostasis, energy substrate partitioning, and intracellular signaling. Moreover, malignant phenotype's chief characteristics are dependent on the interaction between cancer cells and their microenvironment. In breast cancer, mammary adipocytes represent an essential cellular component of the tumor milieu. We analyzed lactate concentration, lactate dehydrogenase (LDH) activity, and isozyme pattern, and LDHA/LDHB protein expression and tissue localization in paired biopsies of breast cancer tissue and cancer-associated adipose tissue in normal-weight and overweight/obese premenopausal women, compared to benign breast tumor tissue and adipose tissue in normal-weight and overweight/obese premenopausal women. We show that higher lactate concentration in cancer tissue is concomitant with a shift in isozyme pattern towards the "muscle-type" LDH and corresponding LDHA and LDHB protein expression changes. In contrast, significantly higher LDH activity in cancer-associated adipose tissue seems to be directed towards lactate oxidation. Moreover, localization patterns of LDH isoforms varied substantially across different areas of breast cancer tissue. Invasive front of the tumor showed cell-specific protein localization of LDHA in breast cancer cells and LDHB in cancer-associated adipocytes. The results suggest a specific, lactate-centric relationship between cancer tissue and cancer-associated adipose tissue and indicate how cancer-adipose tissue cross-talk may be influenced by obesity in premenopausal women.

Human Stromal Cell Aggregates Concentrate Adipose Tissue Constitutive Cell Population by In Vitro DNA Quantification Analysis

BACKGROUND

Regenerative cell strategies rely on stromal cell implants to attain an observable clinical outcome. However, the effective cell dose to ensure a therapeutic response remains unknown. To achieve a higher cell dose, the authors hypothesized that reducing the volume occupied by mature adipocytes in lipoaspirate will concentrate the stromal vascular fraction present in the original tissue.

METHODS

Human standardized lipoaspirate (n = 6) was centrifuged (1200 g for 3 minutes) and the water phase was discarded. Mechanical disaggregation was achieved by shearing tissue through 2.4- and 1.2-mm Luer-to-Luer transfers. After a second centrifugation (800 g for 10 minutes), stromal cell aggregates were separated from the supernatant oil phase. Lipoaspirate percentage composition was determined by its constituent weights. Cell content was measured by total DNA quantification, and partial cell viability was determined by image cytometry. Tissue sections were evaluated histologically (hematoxylin and eosin and Masson trichrome stains).

RESULTS

Stromal cell aggregates reduced the standardized lipoaspirate mass to 28.6 ± 4.2 percent. Accordingly, the cell density increased by 222.6 ± 63.3 percent (from 9.9 ± 1.4 million cells/g to 31.3 ± 6.6 million cells/g; p < 0.05). Cell viability was unaffected in stromal cell aggregates (71.3 ± 2.5 percent) compared to standardized lipoaspirate (72.2 ± 2.3 percent), and histologic analysis revealed high-density areas enriched with stromal cells (622.9 ± 145.6 percent) and extracellular matrix (871.2 ± 80.3 percent).

CONCLUSION

Stromal cell aggregates represent a biological agent that triplicates the cell density versus unprocessed lipoaspirate, low on oil and water fluids, and enriched extracellular matrix components.

Prognostic Value of CT-Attenuation and 18F-Fluorodeoxyglucose Uptake of Periprostatic Adipose Tissue in Patients with Prostate Cancer

This study aimed to assess the prognostic value of computed tomography (CT)-attenuation and ¹⁸F-fluorodeoxyglucose (FDG) uptake of periprostatic adipose tissue (PPAT) for predicting disease progression-free survival (DPFS) in patients with prostate cancer. Seventy-seven patients with prostate cancer who underwent staging FDG positron emission tomography (PET)/CT were retrospectively reviewed. CT-attenuation (HU) and FDG uptake (SUV) of PPAT were measured from the PET/CT images. The relationships between these PPAT parameters and clinical factors were assessed, and a Cox proportional hazard regression test was performed to evaluate the prognostic significance of PPAT HU and SUV. PPAT HU and SUV showed significant positive correlations with tumor stage and serum prostate-specific antigen level (PSA) (p < 0.05). Patients with high PPAT HU and SUV had significantly worse DPFS than those with low PPAT HU and SUV (p < 0.05). In multivariate analysis, PPAT SUV was a significant predictor of DPFS after adjusting for tumor stage, serum PSA, and tumor SUV (p = 0.003; hazard ratio, 1.50; 95% confidence interval, 1.15–1.96). CT-attenuation and FDG uptake of PPAT showed significant association with disease progression in patients with prostate cancer. These imaging findings may be evidence of the role of PPAT in prostate cancer progression.

Autoencoded DNA methylation data to predict breast cancer recurrence: Machine learning models and gene-weight significance

Breast cancer is the most frequent cancer in women and the second most frequent overall after lung cancer. Although the 5-year survival rate of breast cancer is relatively high, recurrence is also common which often involves metastasis with its consequent threat for patients. DNA methylation-derived databases have become an interesting primary source for supervised knowledge extraction regarding breast cancer. Unfortunately, the study of DNA methylation involves the processing of hundreds of thousands of features for every patient. DNA methylation is featured by High Dimension Low Sample Size which has shown well-known issues regarding feature selection and generation. Autoencoders (AEs) appear as a specific technique for conducting nonlinear feature fusion. Our main objective in this work is to design a procedure to summarize DNA methylation by taking advantage of AEs. Our proposal is able to generate new features from the values of CpG sites of patients with and without recurrence. Then, a limited set of relevant genes to characterize breast cancer recurrence is proposed by the application of survival analysis and a pondered ranking of genes according to the distribution of their CpG sites. To test our proposal we have selected a dataset from The Cancer Genome Atlas data portal and an AE with a single-hidden layer. The literature and enrichment analysis (based on genomic context and functional annotation) conducted regarding the genes obtained with our experiment confirmed that all of these genes were related to breast cancer recurrence.

Digital analysis of distant and cancer-associated mammary adipocytes

Adipocytes and cancer-associated adipocytes (CAAs) are poorly investigated cells in the tumor microenvironment. Different image analysis software exist for identifying and measuring these cells using scanned hematoxylin and eosin (H&E)-stained slides. It is however unclear which one is the most appropriate for breast cancer (BC) samples. Here, we compared three software (AdipoCount, Adiposoft, and HALO®). HALO® outperformed the other methods with regard to adipocyte identification, (> 96% sensitivity and specificity). All software performed equally good with regard to area and diameter measurement (concordance correlation coefficients > 0.97 and > 0.96, respectively). We then analyzed a series of 10 BCE samples (n = 51 H&E slides) with HALO®. Distant adipocytes were defined >2 mm away from cancer cells or fibrotic region, whereas CAAs as the first three lines of adipocytes close to the invasive front. Intra-mammary heterogeneity was limited, implying that measuring a single region of ∼500 adipocytes provides a reliable estimation of the distribution of their size features. CAAs had smaller areas (median fold-change: 2.62) and diameters (median fold-change: 1.64) as compared to distant adipocytes in the same breast (both p = 0.002). The size of CAAs and distant adipocytes was associated with the body mass index (BMI) of the patient (area: rho = 0.89, p = 0.001; rho = 0.71, p = 0.027, diameter: rho = 0.87 p = 0.002; rho = 0.65 p = 0.049, respectively). To conclude, we demonstrate that quantifying adipocytes in BC sections is feasible by digital pathology using H&E sections, setting the basis for a standardized analysis of mammary adiposity in larger series of patients.

Bone Marrow Adipocytes, Adipocytokines, and Breast Cancer Cells: Novel Implications in Bone Metastasis of Breast Cancer

Accumulating discoveries highlight the importance of interaction between marrow stromal cells and cancer cells for bone metastasis. Bone is the most common metastatic site of breast cancer and bone marrow adipocytes (BMAs) are the most abundant component of the bone marrow microenvironment. BMAs are unique in their origin and location, and recently they are found to serve as an endocrine organ that secretes adipokines, cytokines, chemokines, and growth factors. It is reasonable to speculate that BMAs contribute to the modification of bone metastatic microenvironment and affecting metastatic breast cancer cells in the bone marrow. Indeed, BMAs may participate in bone metastasis of breast cancer through regulation of recruitment, invasion, survival, colonization, proliferation, angiogenesis, and immune modulation by their production of various adipocytokines. In this review, we provide an overview of research progress, focusing on adipocytokines secreted by BMAs and their potential roles for bone metastasis of breast cancer, and investigating the mechanisms mediating the interaction between BMAs and metastatic breast cancer cells. Based on current findings, BMAs may function as a pivotal modulator of bone metastasis of breast cancer, therefore targeting BMAs combined with conventional treatment programs might present a promising therapeutic option.

Adipocytes: active facilitators in epithelial ovarian cancer progression?

There is growing evidence that adipocytes play important roles in the progression of multiple cancers. Moreover, in obesity, adipocytes alter their original functions and contribute to the metabolic and inflammatory changes of adipose tissue microenvironment, which can further enhance tumor development. At present, the roles of adipocytes in the pathogenesis of epithelial ovarian cancer (EOC) are far from being fully elucidated. Herein, we summarized the recent advances in understanding the roles of adipocytes in EOC progression. Adipocytes, close neighbors of EOC tissue, promote EOC growth, invasion, metastasis and angiogenesis through adipokine secretion, metabolic remodeling and immune microenvironment modulation. Moreover, adipocytes are important therapeutic targets and may work as useful anticancer drug delivery depot for EOC treatment. Furthermore, adipocytes also act as a therapeutic obstacle for their involvement in EOC treatment resistance. Hence, better characterization of the adipocytes in EOC microenvironment and the crosstalk between adipocytes and EOC cells may provide insights into EOC progression and suggest novel therapeutic opportunities.

Hepatic lipids promote liver metastasis

Obesity predisposes to cancer and a virtual universality of nonalcoholic fatty liver disease (NAFLD). However, the impact of hepatic steatosis on liver metastasis is enigmatic. We find that while control mice were relatively resistant to hepatic metastasis, those which were lipodystrophic or obese, with NAFLD, had a dramatic increase in breast cancer and melanoma liver metastases. NAFLD promotes liver metastasis by reciprocal activation initiated by tumor-induced triglyceride lipolysis in juxtaposed hepatocytes. The lipolytic products are transferred to cancer cells via fatty acid transporter protein 1, where they are metabolized by mitochondrial oxidation to promote tumor growth. The histology of human liver metastasis indicated the same occurs in humans. Furthermore, comparison of isolates of normal and fatty liver established that steatotic lipids had enhanced tumor-stimulating capacity. Normalization of glucose metabolism by metformin did not reduce steatosis-induced metastasis, establishing the process is not mediated by the metabolic syndrome. Alternatively, eradication of NAFLD in lipodystrophic mice by adipose tissue transplantation reduced breast cancer metastasis to that of control mice, indicating the steatosis-induced predisposition is reversible.

Nonalcoholic fatty liver disease promotes liver metastasis in mice, likely due to lipid transfer to tumor cells.

Effects of metformin on adipose-derived stromal cell (ADSC) - Breast cancer cell lines interaction

AIMS

Metformin is a clinical drug administered to patients to treat type 2 diabetes mellitus that was found to be associated with a lower risk of occurrence of cancer and cancer-related death. The present study investigated the effects of metformin on human adipose-derived stromal cells (ADSC) - breast cancer cell line interactions.

MAIN METHODS

ADSCs grown from lipoaspirates were tested for growth-stimulating and migration-controlling activity on breast cancer cell lines after pretreatment with metformin. Furthermore, secreted proteins of ADSCs, phosphorylation of intracellular proteins and the effect of metformin on adipocytic differentiation of ADSCs were assayed.

KEY FINDINGS

Compared to breast cancer cell lines (4.0 ± 3.5% reduction of proliferation), 2 mM metformin significantly inhibited the proliferation of ADSC lines (19.2 ± 8.4% reduction of proliferation). This effect on ADSCs seems to be mediated by altered phosphorylation of GSK-3, CREB and PRAS40. Furthermore, treatment with metformin abolished the induction of differentiation of three ADSC lines to adipocytes. 1 and 2 mM metformin significantly impaired the migration of breast cancer cell lines MDA-MB-231 and MDA-MB-436 in scratch assays.

SIGNIFICANCE

Metformin showed low direct inhibitory effects on breast cancer cell lines at physiological concentrations but exerted a significant retardation of the growth and the adipocytic differentiation of ADSCs. Thus, the anticancer activity of metformin in breast cancer at physiological drug concentrations seems to be mediated by an indirect mechanism that lowers the supportive activity of ADSCs.

The Role of Exosomes in the Crosstalk between Adipocytes and Liver Cancer Cells

Exosomes are membrane-bound extracellular vesicles (EVs) that transport bioactive materials between cells and organs. The cargo delivered by exosomes can alter a wide range of cellular responses in recipient cells and play an important pathophysiological role in human cancers. In hepatocellular carcinoma (HCC), for example, adipocyte- and tumor-secreted factors contained in exosomes contribute to the creation of a chronic inflammatory state, which contributes to disease progression. The exosome-mediated crosstalk between adipocytes and liver cancer cells is a key aspect of a dynamic tumor microenvironment. In this review, we summarize the role of increased adiposity and the role of adipocyte-derived exosomes (AdExos) and HCC-derived exosomes (HCCExos) in the modulation of HCC progression. We also discuss recent advances regarding how malignant cells interact with the surrounding adipose tissue and employ exosomes to promote a more aggressive phenotype.

Fatty Acids and Membrane Lipidomics in Oncology: A Cross-Road of Nutritional, Signaling and Metabolic Pathways

Fatty acids are closely involved in lipid synthesis and metabolism in cancer. Their amount and composition are dependent on dietary supply and tumor microenviroment. Research in this subject highlighted the crucial event of membrane formation, which is regulated by the fatty acids' molecular properties. The growing understanding of the pathways that create the fatty acid pool needed for cell replication is the result of lipidomics studies, also envisaging novel fatty acid biosynthesis and fatty acid-mediated signaling. Fatty acid-driven mechanisms and biological effects in cancer onset, growth and metastasis have been elucidated, recognizing the importance of polyunsaturated molecules and the balance between omega-6 and omega-3 families. Saturated and monounsaturated fatty acids are biomarkers in several types of cancer, and their characterization in cell membranes and exosomes is under development for diagnostic purposes. Desaturase enzymatic activity with unprecedented de novo polyunsaturated fatty acid (PUFA) synthesis is considered the recent breakthrough in this scenario. Together with the link between obesity and cancer, fatty acids open interesting perspectives for biomarker discovery and nutritional strategies to control cancer, also in combination with therapies. All these subjects are described using an integrated approach taking into account biochemical, biological and analytical aspects, delineating innovations in cancer prevention, diagnostics and treatments.

Adipose Tissue Properties in Tumor-Bearing Breasts

The tissue stroma plays a major role in tumors' natural history. Most programs for tumor progression are not activated as cell-autonomous processes but under the conditions of cross-talks between tumor and stroma. Adipose tissue is a major component of breast stroma. This study compares adipose tissues in tumor-bearing breasts to those in tumor-free breasts with the intention of defining a signature that could translate into markers of cancer risk. In tumor-bearing breasts, we sampled adipose tissues adjacent to, or distant from the tumor. Parameters studied included: adipocytes size and density, immune cell infiltration, vascularization, secretome and gene expression. Adipose tissues from tumor-bearing breasts, whether adjacent to or distant from the tumor, do not differ from each other by any of these parameters. By contrast, adipose tissues from tumor-bearing breasts have the capacity to secrete twice as much interleukin 8 (IL-8) than those from tumor-free breasts and differentially express a set of 137 genes of which a significant fraction belongs to inflammation, integrin and wnt signaling pathways. These observations show that adipose tissues from tumor-bearing breasts have a distinct physiological status from those from tumor-free breasts. We propose that this constitutive status contributes as a non-cell autonomous process to determine permissiveness for tumor growth.

Breast cancer mammospheres secrete Adrenomedullin to induce lipolysis and browning of adjacent adipocytes

Background

Cancer cells cooperate with cells that compose their environment to promote tumor growth and invasion. Among them, adipocytes provide lipids used as a source of energy by cancer cells and adipokines that contribute to tumor expansion. Mechanisms supporting the dynamic interactions between cancer cells and stromal adipocytes, however, remain unclear.

Methods

We set-up a co-culture model with breast cancer cells grown in 3D as mammospheres and human adipocytes to accurately recapitulate intrinsic features of tumors, such as hypoxia and cancer cell–adipocytes interactions.

Results

Herein, we observed that the lipid droplets’ size was reduced in adipocytes adjacent to the mammospheres, mimicking adipocyte morphology on histological sections. We showed that the uncoupling protein UCP1 was expressed in adipocytes close to tumor cells on breast cancer histological sections as well as in adipocytes in contact with the mammospheres.

Mammospheres produced adrenomedullin (ADM), a multifactorial hypoxia-inducible peptide while ADM receptors were detected in adipocytes. Stimulation of adipocytes with ADM promoted UCP1 expression and increased HSL phosphorylation, which activated lipolysis. Invalidation of ADM in breast cancer cells dramatically reduced UCP1 expression in adipocytes.

Conclusions

Breast tumor cells secreted ADM that modified cancer–associated adipocytes through paracrine signaling, leading to metabolic changes and delipidation. Hence, ADM appears to be crucial in controlling the interactions between cancer cells and adipocytes and represents an excellent target to hinder them.

Fat density is a novel prognostic marker in patients with esophageal cancer

BACKGROUND & AIMS

While long-term obesity is a well-known risk factor for esophageal adenocarcinoma (ADC), recent weight loss represents a significant concern in esophageal cancer (EC), in relation with dysphagia and disease aggressiveness. These phenomenons may diversely impact the adipose tissue density, suggested in other cancer settings as an important prognostic biomarker. The analysis of body mass composition (BMC) parameters, including adipose tissue attenuation is studied here in a population of EC operated with curative intent.

METHODS

BMC was retrospectively evaluated on Computed-Tomography (CT)-scan images from fluorodeoxyglucose (FDG)-positron-emitting (PET)/CT scans performed as a diagnostic procedure in a cohort of 145 EC patients operated with curative intent The mean subcutaneous (SFD) and visceral fat (VFD) density along with the index (area/height²) (SF index (SFI), VF index (VFI)) were assessed on two adjacent slides at the third lumbar vertebra level by two independent investigators. Overall survival (OS) was calculated from the date of the baseline FDG-PET/CT scan.

RESULTS

Inter-observer correlations are excellent for all BMC parameters (r = 0.94-0.99). As expected, weight loss is associated with worse outcome. We show that low SFD (HR 0.5 (95% CI: 0.3-0.7), p < 0.001) and low VFD (HR 0.6 (95% CI: 0.4-0.9), p = 0.04) at diagnosis are associated with better OS. In contrast, body mass index (BMI) fails to show any relevance in predicting survival.

CONCLUSIONS

Adipose tissue density is an important prognostic factor in EC.

The Role of Dysfunctional Adipose Tissue in Pancreatic Cancer: A Molecular Perspective

Pancreatic cancer (PC) is a lethal malignancy with rising incidence and limited therapeutic options. Obesity is a well-established risk factor for PC development. Moreover, it negatively affects outcome in PC patients. Excessive fat accumulation in obese, over- and normal-weight individuals induces metabolic and inflammatory changes of adipose tissue microenvironment leading to a dysfunctional adipose “organ”. This may drive the association between abnormal fat accumulation and pancreatic cancer. In this review, we describe several molecular mechanisms that underpin this association at both local and systemic levels. We focus on the role of adipose tissue-derived circulating factors including adipokines, hormones and pro-inflammatory cytokines, as well as on the impact of the local adipose tissue in promoting PC. A discussion on potential therapeutic interventions, interfering with pro-tumorigenic effects of dysfunctional adipose tissue in PC, is included. Considering the raise of global obesity, research efforts to uncover the molecular basis of the relationship between pancreatic cancer and adipose tissue dysfunction may provide novel insights for the prevention of this deadly disease. In addition, these efforts may uncover novel targets for personalized interventional strategies aimed at improving the currently unsatisfactory PC therapeutic options.

Blackboard to Bedside: A Mathematical Modeling Bottom-Up Approach Toward Personalized Cancer Treatments

Cancers present with high variability across patients and tumors; thus, cancer care, in terms of disease prevention, detection, and control, can highly benefit from a personalized approach. For a comprehensive personalized oncology practice, this personalization should ideally consider data gathered from various information levels, which range from the macroscale population level down to the microscale tumor level, without omission of the central patient level. Appropriate data mined from each of these levels can significantly contribute in devising personalized treatment plans tailored to the individual patient and tumor. Mathematical models of solid tumors, combined with patient-specific tumor profiles, present a unique opportunity to personalize cancer treatments after detection using a bottom-up approach. Here, we discuss how information harvested from mathematical models and from corresponding in silico experiments can be implemented in preclinical and clinical applications. To conceptually illustrate the power of these models, one such model is presented, and various pertinent tumor and treatment scenarios are demonstrated in silico. The presented model, specifically a multiscale, hybrid cellular automaton, has been fully validated in vitro using multiple cell-line-specific data. We discuss various insights provided by this model and other models like it and their role in designing predictive tools that are both patient, and tumor specific. After refinement and parametrization with appropriate data, such in silico tools have the potential to be used in a clinical setting to aid in treatment protocols and decision making.

Selective Alanine Transporter Utilization Creates a Targetable Metabolic Niche in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) evolves a complex microenvironment comprised of multiple cell types, including pancreatic stellate cells (PSC). Previous studies have demonstrated that stromal supply of alanine, lipids, and nucleotides supports the metabolism, growth, and therapeutic resistance of PDAC. Here we demonstrate that alanine cross-talk between PSCs and PDAC is orchestrated by the utilization of specific transporters. PSCs utilize SLC1A4 and other transporters to rapidly exchange and maintain environmental alanine concentrations. Moreover, PDAC cells upregulate SLC38A2 to supply their increased alanine demand. Cells lacking SLC38A2 fail to concentrate intracellular alanine and undergo a profound metabolic crisis resulting in markedly impaired tumor growth. Our results demonstrate that stromal-cancer metabolic niches can form through differential transporter expression, creating unique therapeutic opportunities to target metabolic demands of cancer. SIGNIFICANCE: This work identifies critical neutral amino acid transporters involved in channeling alanine between pancreatic stellate and PDAC cells. Targeting PDAC-specific alanine uptake results in a metabolic crisis impairing metabolism, proliferation, and tumor growth. PDAC cells specifically activate and require SLC38A2 to fuel their alanine demands that may be exploited therapeutically.This article is highlighted in the In This Issue feature, p. 890.

A STAT3 of Addiction: Adipose Tissue, Adipocytokine Signalling and STAT3 as Mediators of Metabolic Remodelling in the Tumour Microenvironment

Metabolic remodelling of the tumour microenvironment is a major mechanism by which cancer cells survive and resist treatment. The pro-oncogenic inflammatory cascade released by adipose tissue promotes oncogenic transformation, proliferation, angiogenesis, metastasis and evasion of apoptosis. STAT3 has emerged as an important mediator of metabolic remodelling. As a downstream effector of adipocytokines and cytokines, its canonical and non-canonical activities affect mitochondrial functioning and cancer metabolism. In this review, we examine the central role played by the crosstalk between the transcriptional and mitochondrial roles of STAT3 to promote survival and further oncogenesis within the tumour microenvironment with a particular focus on adipose-breast cancer interactions.

Revisiting Cancer Stem Cells as the Origin of Cancer-Associated Cells in the Tumor Microenvironment: A Hypothetical View from the Potential of iPSCs

The tumor microenvironment (TME) has an essential role in tumor initiation and development. Tumor cells are considered to actively create their microenvironment during tumorigenesis and tumor development. The TME contains multiple types of stromal cells, cancer-associated fibroblasts (CAFs), Tumor endothelial cells (TECs), tumor-associated adipocytes (TAAs), tumor-associated macrophages (TAMs) and others. These cells work together and with the extracellular matrix (ECM) and many other factors to coordinately contribute to tumor growth and maintenance. Although the types and functions of TME cells are well understood, the origin of these cells is still obscure. Many scientists have tried to demonstrate the origin of these cells. Some researchers postulated that TME cells originated from surrounding normal tissues, and others demonstrated that the origin is cancer cells. Recent evidence demonstrates that cancer stem cells (CSCs) have differentiation abilities to generate the original lineage cells for promoting tumor growth and metastasis. The differentiation of CSCs into tumor stromal cells provides a new dimension that explains tumor heterogeneity. Using induced pluripotent stem cells (iPSCs), our group postulates that CSCs could be one of the key sources of CAFs, TECs, TAAs, and TAMs as well as the descendants, which support the self-renewal potential of the cells and exhibit heterogeneity. In this review, we summarize TME components, their interactions within the TME and their insight into cancer therapy. Especially, we focus on the TME cells and their possible origin and also discuss the multi-lineage differentiation potentials of CSCs exploiting iPSCs to create a society of cells in cancer tissues including TME.

Drilling for Oil: Tumor-Surrounding Adipocytes Fueling Cancer

Over the past decade, it has become apparent that metabolic reprogramming is a key event in tumor progression. The tumor microenvironment (TME) is a source of metabolites for tumor cells. Lipid-filled mature adipocytes are frequently found in proximity to invasive human tumors and release free fatty acids (FFAs) through lipolysis. These FFAs are taken up by tumor cells and used to promote tumor progression by mechanisms that include mitochondrial fatty acid oxidation (FAO). This review discusses recent advances in our understanding of this metabolic symbiosis between adipocytes and cancer cells and underlines the differences in this metabolic crosstalk between the various types of cancer and their localization.

Bioprinted Three-Dimensional Cell-Laden Hydrogels to Evaluate Adipocyte-Breast Cancer Cell Interactions

Three-dimensional (3D) bioprinting, although still in its infancy as a fabrication tool, has the potential to effectively mimic many biological environments. Cell-laden 3D printed structures have demonstrated to be an improvement from the widely used monolayer platforms, largely because of recapitulation of native tissue architecture with the 3D structures. Thus, 3D in vitro models have been increasingly investigated for improved modeling of cell and disease systems, such as for breast cancer. In the present work, multicellular cell-laden hydrogels comprised of adipocytes and breast cancer cells were bioprinted and evaluated. An ideal bioink of 3:2 5% alginate was determined to mimic the tissue stiffness observed in a physiological breast cancer tumor environment. Rheological characterization and degradation studies were performed to verify the stability of the artificial breast hydrogel environment. It was found that both the breast cancer cells and adipocytes remained viable directly after printing and throughout the 10-day culture period within the printed hydrogels. Direct printing of the cells in co-culture resulted in morphology changes and variations in cell localization within printed structures. Overall, the feasibility of efficiently fabricating multicellular cell-laden bioprinted models of the breast tumor microenvironment was established.

Peritumoral Fat Content Correlates with Histological Prognostic Factors in Breast Carcinoma: A Study Using Iterative Decomposition of Water and Fat with Echo Asymmetry and Least-Squares Estimation (IDEAL)

Purpose:

To correlate peritumoral fat content using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with histologic prognostic factors in breast carcinoma.

Methods:

This study consisted of 100 patients who were diagnosed with invasive carcinoma of breast and underwent breast MRI including IDEAL before surgery. The scan time of IDEAL fat fraction (FF) map imaging was 33 s. Four regions of interests (ROIs), which are a distance of 5 mm from the tumor edge, and one ROI in the mammary fat of the healthy side were set on the FF map. Then average peritumoral FF values (FFt), average FF values in the healthy side (FFh), and peritumoral fat ratio (pTFR: defined as FFt/FFh) were calculated. Histologically, the presence of lymph node metastasis and the MIB-1 index were evaluated.

Results:

FFt and pTFR for breast carcinoma with lymph node metastasis (79.27 ± 10.36 and 0.897 ± 0.078) were significantly lower than those without (86.23 ± 4.53 and 0.945 ± 0.032) (P < 0.001 and P = 0.005). Spearman rank correlation suggested that the FFt correlated with the MIB-1 index (r = −340, P = 0.001).

Conclusion:

Quantification of peritumoral fat using IDEAL-iron quantification is associated with the histologic prognostic factors, and may be a practical tool for therapeutic strategy of breast carcinoma.

Lipid mechanisms in hallmarks of cancer

Excess adiposity is a risk factor for several cancer types. This is likely due to complex mechanisms including alterations in the lipid milieu that plays a pivotal role in multiple aspects of carcinogenesis. Here we consider the direct role of lipids in regulating well-known hallmarks of cancer. Furthermore, we suggest that obesity-associated remodelling of membranes and organelles drives cancer cell proliferation and invasion. Identification of cancer-related lipid-mediated mechanisms amongst the broad metabolic disturbances due to excess adiposity is central to the identification of novel and more efficacious prevention and intervention strategies.

Adipocyte extracellular vesicles carry enzymes and fatty acids that stimulate mitochondrial metabolism and remodeling in tumor cells

Extracellular vesicles are emerging key actors in adipocyte communication. Notably, small extracellular vesicles shed by adipocytes stimulate fatty acid oxidation and migration in melanoma cells and these effects are enhanced in obesity. However, the vesicular actors and cellular processes involved remain largely unknown. Here, we elucidate the mechanisms linking adipocyte extracellular vesicles to metabolic remodeling and cell migration. We show that adipocyte vesicles stimulate melanoma fatty acid oxidation by providing both enzymes and substrates. In obesity, the heightened effect of extracellular vesicles depends on increased transport of fatty acids, not fatty acid oxidation-related enzymes. These fatty acids, stored within lipid droplets in cancer cells, drive fatty acid oxidation upon being released by lipophagy. This increase in mitochondrial activity redistributes mitochondria to membrane protrusions of migrating cells, which is necessary to increase cell migration in the presence of adipocyte vesicles. Our results provide key insights into the role of extracellular vesicles in the metabolic cooperation that takes place between adipocytes and tumors with particular relevance to obesity.

Adipocytes in the Tumour Microenvironment

Adipose tissue contribution to body mass ranges from 6% in male athletes to over 25% in obese men and over 30% in obese women. Crosstalk between adipocytes and cancer cells that exist in close proximity can lead to changes in the function and phenotype of both cell types. These interactions actively alter the tumour microenvironment (TME). Obesity is one of the major risk factors for multiple types of cancer, including breast cancer. In obesity, the increase in both size and number of adipocytes leads to instability of the TME, as well as increased hypoxia within the TME, which further enhances tumour invasion and metastasis. In this chapter, we will discuss the diverse aspects of adipocytes and adipocyte-derived factors that affect the TME as well as tumour progression and metastasis. In addition, we discuss how obesity affects the TME. We focus primarily on breast cancer but discuss what is known in other cancer types when relevant. We finish by discussing the studies needed to further understand these complex interactions.

Significance of CT attenuation and F-18 fluorodeoxyglucose uptake of visceral adipose tissue for predicting survival in gastric cancer patients after curative surgical resection

BACKGROUND

The purpose of this study was to investigate the prognostic significance of computed tomography (CT) attenuation and F-18 fluorodeoxyglucose (FDG) uptake of visceral adipose tissue (VAT) to predict peritoneal recurrence-free survival (RFS) as well as RFS and overall survival (OS) in patients with advanced gastric cancer (AGC).

METHODS

We retrospectively enrolled 117 patients with AGC who underwent staging FDG positron emission tomography (PET)/CT and subsequent curative surgical resection. CT attenuation and FDG uptake (SUV) of VAT and maximum FDG uptake of primary tumor (SUVmaxT) were measured from PET/CT images. The relationship of VAT attenuation and SUV with clinico-histopathologic factors and survival was assessed.

RESULTS

There was a significant positive correlation between VAT attenuation and SUV (p < 0.001, r = 0.799). In correlation analyses, both VAT attenuation and SUV showed significant positive correlations with T stage, TNM stage, tumor size, and platelet-to-lymphocyte ratio (p < 0.05), and patients who experienced recurrence during the first 3-year after surgery had significantly higher VAT attenuation and SUV than those who had no recurrence (p < 0.05). Patients with high VAT attenuation and SUV showed significantly worse RFS, peritoneal RFS, and OS than those with low values (p < 0.05). On multivariate survival analysis, VAT attenuation was significantly associated with peritoneal RFS and OS and VAT SUV was significantly associated with OS (p < 0.05).

CONCLUSIONS

CT attenuation and FDG uptake of VAT on staging FDG PET/CT were correlated with tumor characteristics and were significant predictive factors for peritoneal RFS and OS in patients with AGC.

Multifaceted Oncogenic Role of Adipocytes in the Tumour Microenvironment

Obesity has for decades been recognised as one of the major health concerns. Recently accumulated evidence has established that obesity or being overweight is strongly linked to an increased risk of cancer. However, it is still not completely clear how adipose tissue (fat), along with other stromal connective tissues and cells, contribute to tumour initiation and progression. In the tumour microenvironment, the adipose tissue cells, in particular the adipocytes, secrete a number of adipokines, including growth factors, hormones, collagens, fatty acids, and other metabolites as well as extracellular vesicles to shape and condition the tumour and its microenvironment. In fact, the adipocytes, through releasing these factors and materials, can directly and indirectly facilitate cancer cell proliferation, apoptosis, metabolism, angiogenesis, metastasis and even chemotherapy resistance. In this chapter, the multidimensional role played by adipocytes, a major and functional component of the adipose tissue, in promoting cancer development and progression within the tumour microenvironment will be discussed.

Wnt Signaling and Its Significance Within the Tumor Microenvironment: Novel Therapeutic Insights

Wnt signaling is one of the central mechanisms regulating tissue morphogenesis during embryogenesis and repair. The pivot of this signaling cascade is the Wnt ligand, which binds to receptors belonging to the Frizzled family or the ROR1/ROR2 and RYK family. This interaction governs the downstream signaling cascade (canonical/non-canonical), ultimately extending its effect on the cellular cytoskeleton, transcriptional control of proliferation and differentiation, and organelle dynamics. Anomalous Wnt signaling has been associated with several cancers, the most prominent ones being colorectal, breast, lung, oral, cervical, and hematopoietic malignancies. It extends its effect on tumorigenesis by modulating the tumor microenvironment via fine crosstalk between transformed cells and infiltrating immune cells, such as leukocytes. This review is an attempt to highlight the latest developments in the understanding of Wnt signaling in the context of tumors and their microenvironment. A dynamic process known as immunoediting governs the fate of tumor progression based on the correlation of various signaling pathways in the tumor microenvironment and immune cells. Cancer cells also undergo a series of mutations in the tumor suppressor gene, which favors tumorigenesis. Wnt signaling, and its crosstalk with various immune cells, has both negative as well as positive effects on tumor progression. On one hand, it helps in the maintenance and renewal of the leucocytes. On the other hand, it promotes immune tolerance, limiting the antitumor response. Wnt signaling also plays a role in epithelial-mesenchymal transition (EMT), thereby promoting the maintenance of Cancer Stem Cells (CSCs). Furthermore, we have summarized the ongoing strategies used to target aberrant Wnt signaling as a novel therapeutic intervention to combat various cancers and their limitations.