Targeting the IKKβ/mTOR/VEGF signaling pathway as a potential therapeutic strategy for obesity-related breast cancer

Obesity-Associated Cancers: Evidence from Studies in Mouse Models

Obesity, one of the major problems in modern human society, is correlated with various diseases, including type 2 diabetes mellitus (T2DM). In particular, epidemiological and experimental evidence indicates that obesity is closely linked to at least 13 different types of cancer. The mechanisms that potentially explain the link between obesity and cancer include hyperactivation of the IGF pathway, metabolic dysregulation, dysfunctional angiogenesis, chronic inflammation, and interaction between pro-inflammatory cytokines, endocrine hormones, and adipokines. However, how the largely uniform morbidity of obesity leads to different types of cancer still needs to be investigated. To study the link between obesity and cancer, researchers have commonly used preclinical animal models, particularly mouse models. These models include monogenic models of obesity (e.g., ob/ob and db/db mice) and genetically modified mouse models of human cancers (e.g., Kras-driven pancreatic cancer, Apc-mutated colorectal cancer, and Her2/neu-overexpressing breast cancer). The experimental results obtained using these mouse models revealed strong evidence of a link between obesity and cancer and suggested their underlying mechanisms.

Expected and paradoxical effects of obesity on cancer treatment response

Obesity, whose prevalence is pandemic and continuing to increase, is a major preventable and modifiable risk factor for diabetes and cardiovascular diseases, as well as for cancer. Furthermore, epidemiological studies have shown that obesity is a negative independent prognostic factor for several oncological outcomes, including overall and cancer-specific survival, for several site-specific cancers as well as for all cancers combined. Yet, a recently growing body of evidence suggests that sometimes overweight and obesity may associate with better outcomes, and that immunotherapy may show improved response among obese patients compared with patients with a normal weight. The so-called 'obesity paradox' has been reported in several advanced cancer as well as in other diseases, albeit the mechanisms behind this unexpected relationship are still not clear. Aim of this review is to explore the expected as well as the paradoxical relationship between obesity and cancer prognosis, with a particular emphasis on the effects of cancer therapies in obese people.

Chronic Inflammation and Cancer: The Role of Endothelial Dysfunction and Vascular Inflammation

Long-lasting subclinical inflammation is associated with a wide range of human diseases, particularly at a middle and older age. Recent reports showed that there is a direct causal link between inflammation and cancer development, as several cancers were found to be associated with chronic inflammatory conditions. In patients with cancer, healthy endothelial cells regulate vascular homeostasis, and it is believed that they can limit tumor growth, invasiveness, and metastasis. Conversely, dysfunctional endothelial cells that have been exposed to the inflammatory tumor microenvironment can support cancer progression and metastasis. Dysfunctional endothelial cells can exert these effects via diverse mechanisms, including dysregulated adhesion, permeability, and activation of NF-κB and STAT3 signaling. In this review, we highlight the role of vascular inflammation in predisposition to cancer within the context of two common disease risk factors: obesity and smoking. In addition, we discuss the molecular triggers, pathophysiological mechanisms, and the biological consequences of vascular inflammation during cancer development and metastasis. Finally, we summarize the current therapies and pharmacological agents that target vascular inflammation and endothelial dysfunction.

LSM3, NDUFB3, and PTGS2 may be potential biomarkers for BRCA1-mutation positive breast cancer

Purpose: We aimed to find critical biomakers associated with BRCA1-mutation positive breast cancer.

Methods: The data set E-MTAB-982 was downloaded from ArrayExpress database and the data were preprocessed using R package Oligo. Differential expression analysis between BRCA1-mutation positive breast cancer patients and BRCA1-mutation positive healthy subjects were performed using limma package. Then, gene set enrichment analysis was conducted. We constructed the network for BRCA1, its related differentially expressed genes (DEGs), and the enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. After that, survival analysis was performed based on the clinical data of breast cancer in TCGA database. Finally, box diagram for key genes was drawn.

Results: The network showed that LSM3, NDUFB3, GNPDA2, and PTGS2 were BRCA1 related DEGs. Furthermore, LSM3 was mainly enriched in RNA degradation pathway and spliceosome pathway. PTGS2 was enriched in arachidonic acid metabolism and VEGF signaling pathway. Survival analysis indicated that high expression of LSM3 indicated a poor prognosis of BRCA1-mutant breast cancer. Besides, box diagram showed that LSM3 was down-regulated in BRCA1-mutation positive breast cancer patients compared with that in BRCA1-mutation positive healthy subjects.

Conclusions: LSM3, NDUFB3, and PTGS2 may be biomarkers in BRCA1-mutant breast cancer, and high expression of LSM3 may indicate a poor prognosis of BRCA1-mutant breast cancer.

Obesity promotes resistance to anti-VEGF therapy in breast cancer by up-regulating IL-6 and potentially FGF-2

Anti-vascular endothelial growth factor (VEGF) therapy has failed to improve survival in patients with breast cancer (BC). Potential mechanisms of resistance to anti-VEGF therapy include the up-regulation of alternative angiogenic and proinflammatory factors. Obesity is associated with hypoxic adipose tissues, including those in the breast, resulting in increased production of some of the aforementioned factors. Hence, we hypothesized that obesity could contribute to anti-VEGF therapy's lack of efficacy. We found that BC patients with obesity harbored increased systemic concentrations of interleukin-6 (IL-6) and/or fibroblast growth factor 2 (FGF-2), and their tumor vasculature was less sensitive to anti-VEGF treatment. Mouse models revealed that obesity impairs the effects of anti-VEGF on angiogenesis, tumor growth, and metastasis. In one murine BC model, obesity was associated with increased IL-6 production from adipocytes and myeloid cells within tumors. IL-6 blockade abrogated the obesity-induced resistance to anti-VEGF therapy in primary and metastatic sites by directly affecting tumor cell proliferation, normalizing tumor vasculature, alleviating hypoxia, and reducing immunosuppression. Similarly, in a second mouse model, where obesity was associated with increased FGF-2, normalization of FGF-2 expression by metformin or specific FGF receptor inhibition decreased vessel density and restored tumor sensitivity to anti-VEGF therapy in obese mice. Collectively, our data indicate that obesity fuels BC resistance to anti-VEGF therapy via the production of inflammatory and angiogenic factors.

Rapamycin improves bone mass in high-turnover osteoporosis with iron accumulation through positive effects on osteogenesis and angiogenesis

Iron accumulation is an independent risk factor for type I osteoporosis, but the molecular mechanisms of the phenomenon are not well defined, and effective therapy has not been reported. Here, we found that the level of mTOR was increased both in wild-type mouse models with iron accumulation and transgenic mouse models (Hepc^-/-) of high-turnover osteoporosis with iron accumulation. We show that an increased level of mTOR can depress osteogenesis and angiogenesis by Cxcl9 both in bone and in vitro. Suppression of mTOR in mouse models by rapamycin and in vitro by siRNA transfection recovered both osteogenesis and angiogenesis. These findings revealed the role of mTOR in osteogenesis and angiogenesis in high-turnover osteoporosis with iron accumulation and showed that rapamycin targeting of mTOR ameliorates osteogenesis and angiogenesis to improve bone mass.

Dietary Fat and Sugar in Promoting Cancer Development and Progression

The uncontrolled cellular growth that characterizes tumor formation requires a constant delivery of nutrients. Since the 1970s, researchers have wondered if the supply of nutrients from the diet could impact tumor development. Numerous studies have assessed the impact of dietary components, specifically sugar and fat, to increased cancer risk. For the most part, data from these trials have been inconclusive; however, this does not indicate that dietary factors do not contribute to cancer progression. Rather, the dietary contribution may be dependent on tumor, patient, and context, making it difficult to detect in the setting of large trials. In this review, we combine data from prospective cohort trials with mechanistic studies in mice to argue that fat and sugar can play a role in tumorigenesis and disease progression. We find that certain tumors may respond directly to dietary sugar (colorectal and endometrial cancers) and fat (prostate cancer) or indirectly to the obese state (breast cancer).

Characterisation of a Mouse Model of Breast Cancer with Metabolic Syndrome

BACKGROUND/AIM

Patients with breast cancer and metabolic syndrome have poorer outcomes. We aimed to develop and characterise an apolipoprotein E-null/aromatase knockout (ApoE^-/-/ArKO) mouse model of breast cancer with metabolic syndrome to aid research of the mechanisms behind poor prognosis.

MATERIALS AND METHODS

Wild-type, ApoE^-/- and ApoE^-/-/ArKO mice were orthotopically implanted with EO771 murine breast cancer cells. Tumour growth was monitored and tumours investigated for pathological features such as cancer-associated adipocytes, hypoxia and cancer cell proliferation.

RESULTS

Tumours from ApoE^-/-/ArKO mice were significantly more proliferative than those from wild-type mice (p=0.003), and exhibited reduced expression of insulin-like growth factor binding protein-5 (p=0.002). However, ApoE^-/-/ArKO mice also had a reduced rate of metastasis compared to wild-type and ApoE^-/- mice. Tumour hypoxia and the number of cancer-associated adipocytes did not differ.

CONCLUSION

The ApoE^-/-/ArKO model with EO771 breast cancer provides a novel mouse model to investigate the effects of metabolic syndrome on aspects of breast tumour biology.

Energy Balance Modulation Impacts Epigenetic Reprogramming, ERα and ERβ Expression, and Mammary Tumor Development in MMTV-neu Transgenic Mice

The association between obesity and breast cancer risk and prognosis is well established in estrogen receptor (ER)-positive disease but less clear in HER2-positive disease. Here, we report preclinical evidence suggesting weight maintenance through calorie restriction (CR) may limit risk of HER2-positive breast cancer. In female MMTV-HER2/neu transgenic mice, we found that ERα and ERβ expression, mammary tumorigenesis, and survival are energy balance dependent in association with epigenetic reprogramming. Mice were randomized to receive a CR, overweight-inducing, or diet-induced obesity regimen (n = 27/group). Subsets of mice (n = 4/group/time point) were euthanized after 1, 3, and 5 months to characterize diet-dependent metabolic, transcriptional, and epigenetic perturbations. Remaining mice were followed up to 22 months. Relative to the overweight and diet-induced obesity regimens, CR decreased body weight, adiposity, and serum metabolic hormones as expected and also elicited an increase in mammary ERα and ERβ expression. Increased DNA methylation accompanied this pattern, particularly at CpG dinucleotides located within binding or flanking regions for the transcriptional regulator CCCTC-binding factor of ESR1 and ESR2, consistent with sustained transcriptional activation of ERα and ERβ. Mammary expression of the DNA methylation enzyme DNMT1 was stable in CR mice but increased over time in overweight and diet-induced obesity mice, suggesting CR obviates epigenetic alterations concurrent with chronic excess energy intake. In the survival study, CR elicited a significant suppression in spontaneous mammary tumorigenesis. Overall, our findings suggest a mechanistic rationale to prevent or reverse excess body weight as a strategy to reduce HER2-positive breast cancer risk. Cancer Res; 77(9); 2500-11. ©2017 AACR.

Emerging Concepts Linking Obesity with the Hallmarks of Cancer

There is compelling epidemiological evidence linking obesity to many tumours; however, the molecular mechanisms fuelling this association are not clearly understood. Emerging evidence links changes in the tumour microenvironment with the obese state, and murine and human studies highlight the relevance of adipose stromal cells (ASCs), including immune cells, both at remote fat depots, such as the omentum, as well as in peritumoural tissue. These obesity-associated changes have been implicated in several hallmarks of cancer, including the chronic inflammatory state and associated cell signalling, epithelial-to-mesenchymal transition (EMT), tumour-related fibrosis, angiogenesis, and genomic instability. Here, we present a summary of developments over the past 5 years, with particular focus on the tumour microenvironment in the obese state.

Obesity and Cancer: An Angiogenic and Inflammatory Link

With the current epidemic of obesity, a large number of patients diagnosed with cancer are overweight or obese. Importantly, this excess body weight is associated with tumor progression and poor prognosis. The mechanisms for this worse outcome, however, remain poorly understood. We review here the epidemiological evidence for the association between obesity and cancer, and discuss potential mechanisms focusing on angiogenesis and inflammation. In particular, we will discuss how the dysfunctional angiogenesis and inflammation occurring in adipose tissue in obesity may promote tumor progression, resistance to chemotherapy, and targeted therapies such as anti-angiogenic and immune therapies. Better understanding of how obesity fuels tumor progression and therapy resistance is essential to improve the current standard of care and the clinical outcome of cancer patients. To this end, we will discuss how an anti-diabetic drug such as metformin can overcome these adverse effects of obesity on the progression and treatment resistance of tumors.

Lunasin Attenuates Obesity-Associated Metastasis of 4T1 Breast Cancer Cell through Anti-Inflammatory Property

Obesity prevalence is increasing worldwide and is accompanied by low-grade inflammation with macrophage infiltration, which is linked with a poorer breast cancer prognosis. Lunasin is a natural seed peptide with chemopreventive properties and multiple bioactivities. This is the first study to explore the chemopreventive effects of lunasin in the obesity-related breast cancer condition using 4T1 breast cancer cells, 3T3-L1 adipocytes, and conditioned media. An obesity-related environment, such as leptin-treatment or adipocyte-conditioned medium (Ad-CM), promoted 4T1 cell proliferation and metastasis. Lunasin treatment inhibited metastasis of breast cancer cells, partially through modestly inhibiting production of the angiogenesis-mediator vascular endothelial growth factor (VEGF) and significantly by inhibiting secretion in the Ad-CM condition. Subsequently, two adipocytes inflammation models, 3T3-L1 adipocytes were stimulated by tumor necrosis factor (TNF)-α, and RAW 264.7 cell-conditioned medium (RAW-CM) was used to mimic the obese microenvironment. Lunasin significantly inhibited interleukin (IL)-6 and macrophage chemoattractant protein (MCP)-1 secretion by TNF-α stimulation, and MCP-1 secretion in the RAW-CM model. This study highlights that lunasin suppressed 3T3-L1 adipocyte inflammation and inhibited 4T1 breast cancer cell migration. Interestingly, lunasin exerted more effective anti-metastasis activity in the obesity-related condition models, indicating that it possesses anti-inflammatory properties and blocks adipocyte-cancer cell cross-talk.

Measuring relative utilization of aerobic glycolysis in breast cancer cells by positional isotopic discrimination

The ability of cancer cells to produce lactate through aerobic glycolysis is a hallmark of cancer. In this study, we established a positional isotopic labeling and LC-MS-based method that can specifically measure the conversion of glucose to lactate in glycolysis. We show that the rate of aerobic glycolysis is closely correlated with glucose uptake and lactate production in breast cancer cells. We also found that the production of [3-(13) C]lactate is significantly elevated in metastatic breast cancer cells and in early stage metastatic mammary tumors in mice. Our findings may enable the development of a biomarker for the diagnosis of aggressive breast cancer.

A novel bisindole-PBD conjugate inhibits angiogenesis by regulating STAT3 and VEGF in breast cancer cells

AIMS

Breast cancer is highly resistant to chemotherapeutic approach and hence, alternative strategies have been developed to fight against this heterogeneous group of disease. In particular, many studies have demonstrated about various drugs for the treatment of breast cancer. In our study, we assessed the anti-angiogenenic activities of Bisindole-PBD (5b) in MCF-7 and MDA-MB-231 cell lines.

MAIN METHODS

In vitro Endothelial Cell (HUVEC) Tube Formation Assay was performed to show inhibitory role of 5b along with its role upon wound healing process in breast cancer cells in vitro. Semi-quantitative reverse transcription PCR (RT-PCR) was also done to examine the expression of VEGF in response to 5b in breast cancer cells and in HUVEC cells. siRNA transfection study explored STAT3 mediated VEGF transcription in breast cancer cells MCF-7 and MDA-MB-231. CAM assay was performed to see the role of 5b on vessel formation in chicken embryo.

KEY FINDINGS

From in vitro data we have demonstrated that 5b played a role in regulation of breast cancer cell proliferation by inhibiting angiogenesis. Test drug 5b suppressed the expression VEGF at both transcriptional and post transcriptional levels. Apart from this, there was significant down regulation in STAT3 level after drug treatment, which was found to be involved in the VEGF transcription. Metastasis related MMP-2 and MMP-9 expressions were also modulated by 5b. In vivo study by Chick Chorioallantoic Membrane (CAM) Assay also showed anti-angiogenesis role of the test drug which was consistent with the in vitro data.

SIGNIFICANCE

Altogether, our data demonstrated 5b as potent small molecule with anti-angiogenic activities.

Obesity and Breast Cancer: Molecular Interconnections and Potential Clinical Applications

Obesity is an important risk factor for breast cancer (BC) in postmenopausal women; interlinked molecular mechanisms might be involved in the pathogenesis. Increased levels of estrogens due to aromatization of the adipose tissue, inflammatory cytokines such as tumor necrosis factor-α, interleukin-6, and prostaglandin E2, insulin resistance and hyperactivation of insulin-like growth factors pathways, adipokines, and oxidative stress are all abnormally regulated in obese women and contribute to cancerogenesis. These molecular factors interfere with intracellular signaling in the mitogen-activated protein kinase and phosphatydilinositol-3-phosphate/mammalian target of rapamycin (mTOR) pathways, which regulate the progression of the cell cycle, apoptosis, and protein synthesis. In this context, structural defects of typical genes related to both BC and obesity, such as leptin, leptin receptor, serum paraoxonase/arylesterase 1, the fat mass and obesity-associated gene and melanocortin receptor 4, have been associated with a high or low risk of BC development. The early detection of these gene alterations might be useful as risk predictors in obese women, and targeting these pathways involved in the BC pathogenesis in obese women is a potential therapeutic tool. In particular, mTOR pathway deregulation concurs in both obesity and BC, and inhibition of this might disrupt the molecular interlinks in a similar manner to that of metformin, which exerts definite anticancer activity and is currently used as an antidiabetic drug with a weight-reducing property. The identification of both genetic and pharmacological implications on the prevention and management of BC is the ultimate aim of these studies.

IMPLICATIONS FOR PRACTICE

Obese women are at risk of breast cancer, but clinicians lack concrete tools for the prevention or early diagnosis of this risk. The present study, starting from the biology and the molecular defects characterizing both obesity and breast cancer, analyzed the potential molecules and genetic defects whose early identification could delineate a risk profile. Three steps are proposed that are potentially achievable in the clinical assessment of obese women, namely the evaluation of altered levels of serum molecules, the identification of genetic polymorphisms, and the study of the transcriptomic profile of premalignant lesions. Finally, the therapeutic implications of this molecular assessment were evaluated.

PlGF/VEGFR-1 Signaling Promotes Macrophage Polarization and Accelerated Tumor Progression in Obesity

PURPOSE

Obesity promotes pancreatic and breast cancer progression via mechanisms that are poorly understood. Although obesity is associated with increased systemic levels of placental growth factor (PlGF), the role of PlGF in obesity-induced tumor progression is not known. PlGF and its receptor VEGFR-1 have been shown to modulate tumor angiogenesis and promote tumor-associated macrophage (TAM) recruitment and activity. Here, we hypothesized that increased activity of PlGF/VEGFR-1 signaling mediates obesity-induced tumor progression by augmenting tumor angiogenesis and TAM recruitment/activity.

EXPERIMENTAL DESIGN

We established diet-induced obese mouse models of wild-type C57BL/6, VEGFR-1 tyrosine kinase (TK)-null, or PlGF-null mice, and evaluated the role of PlGF/VEGFR-1 signaling in pancreatic and breast cancer mouse models and in human samples.

RESULTS

We found that obesity increased TAM infiltration, tumor growth, and metastasis in pancreatic cancers, without affecting vessel density. Ablation of VEGFR-1 signaling prevented obesity-induced tumor progression and shifted the tumor immune environment toward an antitumor phenotype. Similar findings were observed in a breast cancer model. Obesity was associated with increased systemic PlGF, but not VEGF-A or VEGF-B, in pancreatic and breast cancer patients and in various mouse models of these cancers. Ablation of PlGF phenocopied the effects of VEGFR-1-TK deletion on tumors in obese mice. PlGF/VEGFR-1-TK deletion prevented weight gain in mice fed a high-fat diet, but exacerbated hyperinsulinemia. Addition of metformin not only normalized insulin levels but also enhanced antitumor immunity.

CONCLUSIONS

Targeting PlGF/VEGFR-1 signaling reprograms the tumor immune microenvironment and inhibits obesity-induced acceleration of tumor progression. Clin Cancer Res; 22(12); 2993-3004. ©2016 AACR.

Aspirin Breaks the Crosstalk between 3T3-L1 Adipocytes and 4T1 Breast Cancer Cells by Regulating Cytokine Production

Breast cancer is one of the most common cancers in women worldwide. The obesity process is normally accompanied by chronic, low-grade inflammation. Infiltration by inflammatory cytokines and immune cells provides a favorable microenvironment for tumor growth, migration, and metastasis. Epidemiological evidence has shown that aspirin is an effective agent against several types of cancer. The aim of this study is to investigate the anti-inflammatory and anti-cancer effects of aspirin on 3T3-L1 adipocytes, 4T1 murine breast cancer cells, and their crosstalk. The results showed that aspirin treatment inhibited differentiation and lipid accumulation by 3T3-L1 preadipocytes, and decreased the secretion of the inflammatory adipokine MCP-1 after stimulation with tumor necrosis factor (TNF)-α or conditioned medium from RAW264.7 cells. In 4T1 cells, treatment with aspirin decreased cell viability and migration, possibly by suppressing MCP-1 and VEGF secretion. Subsequently, culture of 4T1 cells in 3T3-L1 adipocyte-conditioned medium (Ad-CM) and co-culture of 3T3-L1 and 4T1 cells using a transwell plate were performed to clarify the relationship between these two cell lines. Aspirin exerted its inhibitory effects in the transwell co-culture system, as well as the conditioned-medium model. Aspirin treatment significantly inhibited the proliferation of 4T1 cells, and decreased the production of MCP-1 and PAI-1 in both the Ad-CM model and co-culture system. Aspirin inhibited inflammatory MCP-1 adipokine production by 3T3-L1 adipocytes and the cell growth and migration of 4T1 cells. It also broke the crosstalk between these two cell lines, possibly contributing to its chemopreventive properties in breast cancer. This is the first report that aspirin’s chemopreventive activity supports the potential application in auxiliary therapy against obesity-related breast cancer development.

Carglumic acid promotes apoptosis and suppresses cancer cell proliferation in vitro and in vivo

Drug repurposing is a therapeutic strategy that applies drugs to treat different diseases based on new therapeutic function. Carglumic acid (Carbaglu; Orphan Europe) is an orphan drug approved by the FDA for hyperammonemia. Administration of carglumic acid for treatment of hyperammonemia has few side effects and has been used for 10 years to effectively treat hyperammonemia symptoms of both adult and pediatric patients. Here, we tested the potential of carglumic acid to be repurposed as an anticancer agent and showed that carglumic acid promotes apoptosis and inhibits cancer cell growth ina wide variety of human cancers, including pancreatic ductal adenocarcinoma, triple-negative breast cancer (TNBC), hepatoma, and lung cancer. Our data from in vivo models indicates that orally taking 10% of the carglumic acid dose currently used for the treatment of hyperammonemia ise ffective to suppress the growth of pancreatic ductal adenocarcinomaand TNBC. If given intravenously, only 5% of the carglumic acid doseis needed to be effective against TNBC. These findings suggest that carglumic acid may serve as a safe and effective therapeutic to treat both TNBC and pancreatic cancer.

Local adipocyte cancer cell paracrine loop: can "sick fat" be more detrimental?

This review article focuses on the emerging role of tumor resident adipocytes. It provides in vitro and in vivo evidence that they are essential for cancer development/progression. In addition to systemic effects, their tumor-promoting impact is dependent on local functions, notably via a complex adipocyte cancer cell paracrine loop (ACCPL). Indeed, this event leads to dramatic phenotypic and/or functional modifications of both cell types as well as of the extracellular matrix. Adipocytes undergo delipidation leading to adipocytes/cancer-associated adipocytes/cancer-associated fibroblasts de-differentiation processes. In turn, cancer cell aggressiveness is exacerbated through increased proliferation, migration, and invasion properties. This is accompanied by intense tissue remodeling, conducting to the occurrence of the tumor stroma. The molecular pathways involved in ACCPL remain largely unknown. Nevertheless, several clues are starting to emerge. Moreover, obesity is currently a sign of increased risk and poor prognosis in human carcinomas. How adiposopathy might impact tumors and specifically the ACCPL is still under investigation. However, available experimental, epidemiological, and clinical data allow to draw some directions. Interestingly, there are numerous similarities between the ACCPL-induced and obesity-related molecular alterations. It might, therefore, be hypothesized that obesity provides a "constitutively active" local permissive environment for cancer cells. Improving our knowledge about ACCPL in both lean and obese patients remains a challenging task. Indeed, deciphering the cellular and molecular mechanisms behind ACCPL might provide new targets for improving diagnosis/prognosis and the design of innovative therapeutic strategies, and even, in case of obesity, for preventing cancer.

Tanshinone IIA inhibits HIF-1α and VEGF expression in breast cancer cells via mTOR/p70S6K/RPS6/4E-BP1 signaling pathway

Hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) play important roles in angiogenesis and tumor growth. Tanshinone IIA (T2A) is a novel antiangiogenic agent with promising antitumor effects; however, the molecular mechanism underlying the antiangiogenic effects of T2A remains unclear. In the present study, we provided evidence showing that T2A inhibited angiogenesis and breast cancer growth by down-regulating VEGF expression. Specifically, T2A repressed HIF-1α expression at the translational level and inhibited the transcriptional activity of HIF-1α, which led to the down-regulation of VEGF expression. Suppression of HIF-1α synthesis by T2A correlated with strong dephosphorylation of mammalian target of rapamycin (mTOR) and its effectors ribosomal protein S6 kinase (p70S6K) and eukaryotic initiation factor 4E-binding protein-1 (4E-BP1), a pathway regulating HIF-1α expression at the translational level. In addition, we also found that T2A inhibited the angiogenesis and growth of human breast cancer xenografts in nude mice through suppression of HIF-1α and VEGF. Our study provides novel perspectives and potential targets for the treatment of human breast cancer.

Effects of obesity on transcriptomic changes and cancer hallmarks in estrogen receptor-positive breast cancer

Background

Obesity increases the risk of cancer death among postmenopausal women with estrogen receptor–positive (ER+) breast cancer, but the direct evidence for the mechanisms is lacking. The purpose of this study is to demonstrate direct evidence for the mechanisms mediating this epidemiologic phenomenon.

Methods

We analyzed transcriptomic profiles of pretreatment biopsies from a prospective cohort of 137 ER+ breast cancer patients. We generated transgenic (MMTV-TGFα;A^y/a) and orthotopic/syngeneic (A^y/a) obese mouse models to investigate the effect of obesity on tumorigenesis and tumor progression and to determine biological mechanisms using whole-genome transcriptome microarrays and protein analyses. We used a coculture system to examine the impact of adipocytes/adipokines on breast cancer cell proliferation. All statistical tests were two-sided.

Results

Functional transcriptomic analysis of patients revealed the association of obesity with 59 biological functional changes (P < .05) linked to cancer hallmarks. Gene enrichment analysis revealed enrichment of AKT-target genes (P = .04) and epithelial–mesenchymal transition genes (P = .03) in patients. Our obese mouse models demonstrated activation of the AKT/mTOR pathway in obesity-accelerated mammary tumor growth (3.7- to 7.0-fold; P < .001; n = 6–7 mice per group). Metformin or everolimus can suppress obesity-induced secretion of adipokines and breast tumor formation and growth (0.5-fold, P = .04; 0.3-fold, P < .001, respectively; n = 6–8 mice per group). The coculture model revealed that adipocyte-secreted adipokines (eg, TIMP-1) regulate adipocyte-induced breast cancer cell proliferation and invasion. Metformin suppress adipocyte-induced cell proliferation and adipocyte-secreted adipokines in vitro.

Conclusions

Adipokine secretion and AKT/mTOR activation play important roles in obesity-accelerated breast cancer aggressiveness in addition to hyperinsulinemia, estrogen signaling, and inflammation. Metformin and everolimus have potential for therapeutic interventions of ER+ breast cancer patients with obesity.

Vascular endothelial growth factor (VEGF), mast cells and inflammation

Vascular endothelial growth factor (VEGF) is one of the most important inducers of angiogenesis, therefore blocking angiogenesis has led to great promise in the treatment of various cancers and inflammatory diseases. VEGF, expressed in response to soluble mediators such as cytokines and growth factors, is important in the physiological development of blood vessels as well as development of vessels in tumors. In cancer patients VEGF levels are increased, and the expression of VEGF is associated with poor prognosis in diseases. VEGF is a mediator of angiogenesis and inflammation which are closely integrated processes in a number of physiological and pathological conditions including obesity, psoriasis, autoimmune diseases and tumor. Mast cells can be activated by anti-IgE to release potent mediators of inflammation and can also respond to bacterial or viral antigens, cytokines, growth factors and hormones, leading to differential release of distinct mediators without degranulation. Substance P strongly induces VEGF in mast cells, and IL-33 contributes to the stimulation and release of VEGF in human mast cells in a dose-dependent manner and acts synergistically in combination with Substance P. Here we report a strong link between VEGF and mast cells and we depict their role in inflammation and immunity.

Deconvoluting the obesity and breast cancer link: secretome, soil and seed interactions

Obesity is associated with increased risk of breast cancer in postmenopausal women and is linked with poor prognosis in pre- and postmenopausal breast cancer patients. The mechanisms underlying the obesity-breast cancer connection are becoming increasingly clear and provide multiple opportunities for primary to tertiary prevention. Several obesity-related host factors can influence breast tumor initiation, progression and/or response to therapy, and these have been implicated as key contributors to the complex effects of obesity on cancer incidence and outcomes. These host factors include components of the secretome, including insulin, insulin-like growth factor-1, leptin, adiponectin, steroid hormones, cytokines, vascular regulators, and inflammation-related molecules, as well as the cellular and structural components of the tumor microenvironment. These secreted and structural host factors are extrinsic to, and interact with, the intrinsic molecular characteristics of breast cancer cells (including breast cancer stem cells), and each will be considered in the context of energy balance and as potential targets for cancer prevention.

Molecular pathways: adipose inflammation as a mediator of obesity-associated cancer

The increasing rate of obesity worldwide is predicted to be associated with a surge in diseases. Notably, obesity has been linked to approximately 20% of cancer cases in the United States; obesity is associated with both increased risk and worse outcomes after diagnosis. Altered levels of circulating factors are strongly implicated, including insulin, insulin-like growth factor 1, leptin, adiponectin, and interleukin-6 (IL-6). In addition, increasing attention has focused on the consequences of local adipose inflammation. Inflammatory foci characterized by crown-like structures consisting of dead adipocytes encircled by macrophages occur in white adipose depots, including the breast tissue, of most overweight and obese women. Saturated fatty acids, released as a consequence of obesity-associated lipolysis, induce macrophage activation via Toll-like receptor 4, thereby stimulating NF-κB signaling. This, in turn, activates transcription of proinflammatory genes including COX-2, IL-6, IL-1β, and TNFα. Elevated levels of proinflammatory mediators cause both local and systemic effects. Of particular relevance with regard to breast cancer is increased transcription of the CYP19 gene encoding aromatase, the rate-limiting enzyme for estrogen synthesis. Notably, this obesity-inflammation-aromatase axis provides a plausible explanation for increased rates of postmenopausal, hormone receptor-positive breast cancer associated with obesity and hence may offer targets for interventions to attenuate risk or improve prognosis. Potential approaches include weight reduction, exercise, and suppression of obesity-driven signaling pathways using pharmaceutical or dietary agents. A key future goal is to identify biomarkers that accurately report adipose inflammation, both for identification of at-risk individuals and to assess the efficacy of interventions. Clin Cancer Res; 19(22); 6074-83. ©2013 AACR.

Obesity increases the incidence of distant metastases in oestrogen receptor-negative human epidermal growth factor receptor 2-positive breast cancer patients

BACKGROUND

Obesity is a major negative determinant of breast cancer outcome. However, there are contrasting data on the differential impact of obesity on specific breast cancer subtypes. In particular, very little is known on human epidermal growth factor receptor 2-positive (HER2+) tumours.

PATIENTS AND METHODS

We assessed the prognostic role of increased body mass index (BMI) on a consecutive series of non-metastatic HER2+ patients treated at our institution before the introduction of adjuvant Trastuzumab. We separately analysed oestrogen receptor-positive (ER+) and -negative (ER-) HER2+ cases.

RESULTS

In ER-/HER2+ tumours we observed a significantly worse overall survival (Hazard ratio (HR) 1.79, p-value 0.041) and cumulative incidence of distant metastases (HR 2.03, p-value 0.019) in obese (BMI>30) versus normal/underweight (BMI<25) patients. Local relapses appeared to be non-significantly reduced in obese patients, masking the overall effect on disease-free survival. Outcome in ER+ tumours, instead, was not significantly different between BMI groups.

CONCLUSIONS

Obesity significantly correlates with worse overall survival and cumulative incidence of distant metastases in ER-/HER2 positive breast cancer. Differences in the biology of breast tumours may determine individual susceptibility to obesity. The biology of the underlying tumour should be taken into account in the design of dietary intervention trials in breast cancer.

Diet, obesity, and cancer progression: are adipocytes the link?

Obesity has been linked to more aggressive characteristics of several cancers, including breast and prostate cancer. Adipose tissue appears to contribute to paracrine interactions in the tumor microenvironment. In particular, cancer-associated adipocytes interact reciprocally with cancer cells and influence cancer progression. Adipokines secreted from adipocytes likely form a key component of the paracrine signaling in the tumor microenvironment. In vitro coculture models allow for the assessment of specific adipokines in this interaction. Furthermore, micronutrients and macronutrients present in the diet may alter the secretion of adipokines from adipocytes. The effect of dietary fat and specific fatty acids on cancer progression in several in vivo model systems and cancer types is reviewed. The more common approaches of caloric restriction or diet-induced obesity in animal models establish that such dietary changes modulate tumor biology. This review seeks to explore available evidence regarding how diet may modulate tumor characteristics through changes in the role of adipocytes in the tumor microenvironment.