Modulatory effects of adiponectin on the polarization of tumor-associated macrophages

Role of Leptin and Adiponectin in Carcinogenesis

Hormones produced by adipocytes, leptin and adiponectin, are associated with the process of carcinogenesis. Both of these adipokines have well-proven oncologic potential and can affect many aspects of tumorigenesis, from initiation and primary tumor growth to metastatic progression. Involvement in the formation of cancer includes interactions with the tumor microenvironment and its components, such as tumor-associated macrophages, cancer-associated fibroblasts, extracellular matrix and matrix metalloproteinases. Furthermore, these adipokines participate in the epithelial-mesenchymal transition and connect to angiogenesis, which is critical for cancer invasiveness and cancer cell migration. In addition, an enormous amount of evidence has demonstrated that altered concentrations of these adipocyte-derived hormones and the expression of their receptors in tumors are associated with poor prognosis in various types of cancer. Therefore, leptin and adiponectin dysfunction play a prominent role in cancer and impact tumor invasion and metastasis in different ways. This review clearly and comprehensively summarizes the recent findings and presents the role of leptin and adiponectin in cancer initiation, promotion and progression, focusing on associations with the tumor microenvironment and its components as well as roles in the epithelial-mesenchymal transition and angiogenesis.

Obesity Programs Macrophages to Support Cancer Progression

Obesity induces multifactorial effects such as dyslipidemia, insulin resistance, and arterial hypertension that influence the progression of many diseases. Obesity is associated with an increased incidence of cancers, and multiple mechanisms link obesity with cancer initiation and progression. Macrophages participate in the homeostasis of adipose tissue and play an important role in cancer. Adipose tissue expansion in obesity alters the balance between pro- and anti-inflammatory macrophages, which is a primary cause of inflammation. Chronic low-grade inflammation driven by macrophages is also an important characteristic of cancer. Adipocytes secrete various adipokines, including adiponectin, leptin, IL6, and TNFα, that influence macrophage behavior and tumor progression. Furthermore, other metabolic effects of obesity, such as hyperlipidemia, hyperglycemia, and hypercholesterolemia, can also regulate macrophage functionality in cancer. This review summarizes how obesity influences macrophage-tumor cell interactions and the role of macrophages in the response to anticancer therapies under obese conditions.

Adiponectin Suppresses Metastasis of Nasopharyngeal Carcinoma through Blocking the Activation of NF-κB and STAT3 Signaling

Adiponectin is an adipocytokine with anti-inflammatory and anticancer properties. Our previous study has shown that blood adiponectin levels were inversely correlated to the risk of nasopharyngeal carcinoma (NPC), and that adiponectin could directly suppress the proliferation of NPC cells. However, the effect of adiponectin on NPC metastasis remains unknown. Here, we revealed in clinical studies that serum adiponectin level was inversely correlated with tumor stage, recurrence, and metastasis in NPC patients, and that low serum adiponectin level also correlates with poor metastasis-free survival. Coculture with recombinant adiponectin suppressed the migration and invasion of NPC cells as well as epithelial-mesenchymal transition (EMT). In addition, recombinant adiponectin dampened the activation of NF-κB and STAT3 signaling pathways induced by adipocyte-derived proinflammatory factors such as leptin, IL-6, and TNF-α. Pharmacological activation of adiponectin receptor through its specific agonist, AdipoRon, largely stalled the metastasis of NPC cells. Taken together, these findings demonstrated that adiponectin could not only regulate metabolism and inhibit cancer growth, but also suppress the metastasis of NPC. Pharmacological activation of adiponectin receptor may be a promising therapeutic strategy to stall NPC metastasis and extend patients' survival.

Phosphoinositide 3-kinase/Akt and its related signaling pathways in the regulation of tumor-associated macrophages polarization

Tumor-associated macrophages (TAMs) are a type of functionally plastic immune cell population in tumor microenvironment (TME) and mainly polarized into two phenotypes: M2 and M1-like TAMs. The M2-like TAMs could stimulate tumor growth and metastasis, tissue remodeling and immune-suppression, whereas M1-like TAMs could initiate immune response to dampen tumor progression. TAMs with different polarization phenotypes can produce various kinds of cytokines, chemokines and growth factors to regulate immunity and inflammatory responses. It is an effective method to treat cancer through ameliorating TME and modulating TAMs by converting M2 into M1-like phenotype. However, intracellular signaling mechanisms underlying TAMs polarization are largely undefined. Phosphoinositide 3-kinase (PI3K)/Akt is an important signaling pathway participating in M2-like TAMs polarization, survival, growth, proliferation, differentiation, apoptosis and cytoskeleton rearrangement. In the present review, we analyzed the mechanism of TAMs polarization focusing on PI3K/Akt and its downstream mitogen‑activated protein kinase (MAPK) as well as nuclear factor kappa B (NF-κB) signaling pathways, thus provides the first evidence of intracellular targets for cancer immunotherapy.

Adiponectin Deficiency Enhances Anti-Tumor Immunity of CD8+ T Cells in Rhabdomyosarcoma Through Inhibiting STAT3 Activation

Restoring the tumor-killing function of CD8+ T cells in the tumor microenvironment is an important strategy for cancer immunotherapy. Our previous study indicated that adiponectin (APN) deficiency reprogramed tumor-associated macrophages into an M1-like phenotype to inhibit rhabdomyosarcoma growth. However, whether APN can directly regulate the anti-tumor activity of CD8+ T cells remains unknown. In the present study, our results showed that exogenous APN inhibited in vitro CD8+ T cell migration as well as cytokines IFN-γ and TNF-α production. APN deficiency in vivo strengthened CD8+ T cell activation and cytotoxicity to restrain rhabdomyosarcoma, evidenced by an increase in the expression of IFN-γ and perforin in CD8+ T cells and the frequency of CD8+IFN-γ+ T cells in the spleen and lymph nodes, as well as increasing cytokine production of IFN-γ, perforin, TNF-α, and decreasing cytokine production of IL-10 in the serum. Mechanistically, STAT3 was identified as a target of APN in negatively regulating the anti-tumor activity of CD8+ T cells. In vivo, a STAT3 inhibitor remarkably increased CD8+ as well as CD8+IFN-γ+ T cells in the spleen and lymph nodes. Taken together, we substantiated that APN deficiency directly maintains the activation of CD8+ T cells to inhibit rhabdomyosarcoma growth by suppressing STAT3 activation, indicating a promising APN-based therapy for the treatment of rhabdomyosarcoma.

Adiponectin Deficiency Suppresses Rhabdomyosarcoma Associated with Gut Microbiota Regulation

The gut microbiota is very important in the initiation, progression, and dissemination of cancer, and the regulation of microbiota has been employed as a novel strategy to enhance the effect of immunotherapy. Adiponectin (APN), an adipocyte-derived hormone, plays a vital role in regulating the immune response of innate immune cells. The deficiency of APN inhibits rhabdomyosarcoma growth. However, whether this function is associated with regulating gut microbiota remains unknown. To investigate, we performed 16S ribosomal RNA (rRNA) gene sequencing on the fecal microbiome of APN gene knockout mice to determine whether APN deletion affects the gut microbiota. We found APN deficiency alters gut microbial functions involved in metabolism, genetic information processing, and cellular processes. In addition, a decreased abundance of Bacteroides and an increased abundance of Prevotella and Helicobacter were observed in rhabdomyosarcoma-bearing APN knockout mice; these bacteria were associated with the inhibition of rhabdomyosarcoma growth. These findings suggest that gut microbiota may be a potential target of APN deficiency against rhabdomyosarcoma.

Metabolic regulatory crosstalk between tumor microenvironment and tumor-associated macrophages

Macrophages phagocytize pathogens to initiate innate immunity and products from the tumor microenvironment (TME) to mediate tumor immunity. The loss of tumor-associated macrophage (TAM)-mediated immune responses results in immune suppression. To reverse this immune disorder, the regulatory mechanism of TAMs in the TME needs to be clarified. Immune molecules (cytokines and chemokines) from TAMs and the TME have been widely accepted as mutual mediators of signal transduction in the past few decades. Recently, researchers have tried to seek the intrinsic mechanism of TAM phenotypic and functional changes through metabolic connections. Numerous metabolites derived from the TME have been identified that induce the cell-cell crosstalk with TAMs. The bulk tumor cells, immune cells, and stromal cells produce metabolites in the TME that are involved in the metabolic regulation of TAMs. Meanwhile, some products from TAMs regulate the biological functions of the tumor as well. Here, we review the recent reports demonstrating the metabolic regulation between TME and TAMs.

SerpinB2 inhibits migration and promotes a resolution phase signature in large peritoneal macrophages

SerpinB2 (plasminogen activator inhibitor type 2) has been called the "undecided serpin" with no clear consensus on its physiological role, although it is well described as an inhibitor of urokinase plasminogen activator (uPA). In macrophages, pro-inflammatory stimuli usually induce SerpinB2; however, expression is constitutive in Gata6+ large peritoneal macrophages (LPM). Interrogation of expression data from human macrophages treated with a range of stimuli using a new bioinformatics tool, CEMiTool, suggested that SerpinB2 is most tightly co- and counter-regulated with genes associated with cell movement. Using LPM from SerpinB2-/- and SerpinB2R380A (active site mutant) mice, we show that migration on Matrigel was faster than for their wild-type controls. Confocal microscopy illustrated that SerpinB2 and F-actin staining overlapped in focal adhesions and lamellipodia. Genes associated with migration and extracellular matrix interactions were also identified by RNA-Seq analysis of migrating RPM from wild-type and SerpinB2R380A mice. Subsequent gene set enrichment analyses (GSEA) suggested SerpinB2 counter-regulates many Gata6-regulated genes associated with migration. These data argue that the role of SerpinB2 in macrophages is inhibition of uPA-mediated plasmin generation during cell migration. GSEA also suggested that SerpinB2 expression (likely via ensuing modulation of uPA-receptor/integrin signaling) promotes the adoption of a resolution phase signature.

The Role of Metabolic Syndrome in Endometrial Cancer: A Review

Endometrial cancer is one of the most common cancers of the female reproductive system. Although surgery, radiotherapy, chemotherapy, and hormone therapy can significantly improve the survival of patients, the treatment of patients with very early lesions and a strong desire to retain reproductive function or late recurrence is still in the early stages. Metabolic syndrome (MS) is a clustering of at least three of the five following medical conditions: central obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL). Obesity, diabetes and hypertension often coexist in patients with endometrial cancer, which increases the risk of endometrial cancer, also known as the "triple syndrome of endometrial cancer." In recent years, epidemiological and clinical studies have found that MS associated with metabolic diseases is closely related to the incidence of endometrial cancer. However, the key molecular mechanisms underlying the induction of endometrial cancer by MS have not been elucidated to date. Characterizing the tumor metabolism microenvironment will be advantageous for achieving a comprehensive view of the molecular mechanism of metabolic syndrome associated with endometrial cancer and for providing a new target for the treatment of endometrial cancer. This review focuses on recent advances in determining the role of metabolic syndrome-related factors and mechanisms in the pathogenesis of endometrial cancer. We suggest that interfering with the tumor metabolic microenvironment-related molecular signals may inhibit the occurrence of endometrial cancer.

The γ-secretase inhibitor GSI-I interacts synergistically with the proteasome inhibitor bortezomib to induce ALK+ anaplastic large cell lymphoma cell apoptosis

Single agent treatment of the γ-secretase inhibitor (GSI-I) or proteasome inhibitor in anaplastic lymphoma kinase positive anaplastic large cell lymphoma (ALK+ ALCL) shows limited response and considerable toxicity. Here, we examined the effects of the combination of low dose GSI-I and the proteasome inhibitor bortezomib (BTZ) in ALK+ ALCL cells in vivo and in vitro. We found that ALK+ ALCL cells treated with the BTZ and GSI-I combination treatment showed elevated apoptosis, consistent with increased caspase activation, compared with BTZ or GSI-I alone. The combination treatment also inhibited AKT and extracellular signal-related kinase pathways, as well as stress-related cascades, including the c-jun N-terminal kinase and stress-activated kinases. Moreover, combined treatment in a murine xenograft model resulted in increased apoptosis in tumor tissues and reduced tumor growth. Our results reveal the synergistic anti-tumor effects of low dose inhibitors against γ-secretase and the proteasome and suggest the potential application of the tolerable BTZ/GSI-I combined agents in treating ALK+ ALCL in future clinical treatment.

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

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

Adiponectin inhibits migration and invasion by reversing epithelial‑mesenchymal transition in non‑small cell lung carcinoma

Adiponectin is the most abundant adipokine in the tumor microenvironment. The role of this protein in tumor progression, however, remains controversial. In the present study, we aimed to investigate the effects of adiponectin on the abilities of migration and invasion in non-small cell lung carcinoma (NSCLC). Using NSCLC cell lines, we examined the effects of adiponectin on cell migration and invasion using Transwell assays. Expression of epithelial-mesenchymal transition markers was examined via microscopy and western blotting. We also performed a knockdown of Twist, AdipoR1 and AdipoR2 in NSCLC cells with siRNAs. The addition of adiponectin to NSCLC cells inhibited both the migration and invasion abilities. Furthermore, we found that NSCLC cells displayed increased epithelial marker expression and downregulation of mesenchymal marker expression following adiponectin administration. Twist AdipoR1 and AdipoR2 knockdown reversed the inhibitory effects of adiponectin on migration and invasion in NSCLC and epithelial-mesenchymal transition. Exogenous adiponectin significantly impaired the migratory and invasive capacities of NSCLC cells through reversal of EMT, suggesting that adiponectin may be a novel promising therapeutic approach against NSCLC.

A key role of GARP in the immune suppressive tumor microenvironment

In melanoma patients, one of the main reasons for tumor immune escape and therapy failure is the immunosuppressive tumor microenvironment. Herein, suppressive immune cells and inhibitory factors secreted by the tumor itself play a central role.

In the present study we show that the Treg activation marker GARP (glycoprotein A repetitions predominant), known to induce peripheral tolerance in a TGF-β dependent way, is also expressed on human primary melanoma. Interestingly, membrane bound GARP is shed from the surface of both, activated Treg and melanoma cells, and, in its soluble form (sGARP), not only induces peripheral Treg but also a tumor associated (M2) macrophage phenotype. Notably, proliferation of cytotoxic T cells and their effector function is inhibited in the presence of sGARP. GARP expression on Treg and melanoma cells is significantly decreased in the presence of agents such as IFN-α, thus explaining at least in part a novel mechanism of action of this adjuvant therapy.

In conclusion, GARP in its soluble and membrane bound form contributes to peripheral tolerance in a multipronged way, potentiates the immunosuppressive tumor microenvironment and thus acts as a negative regulator in melanoma patients. Therefore, it may qualify as a promising target and a new checkpoint for cancer immunotherapy.

PI3K Inhibition Reduces Mammary Tumor Growth and Facilitates Antitumor Immunity and Anti-PD1 Responses

Purpose: Metastatic breast cancers continue to elude current therapeutic strategies, including those utilizing PI3K inhibitors. Given the prominent role of PI3Kα,β in tumor growth and PI3Kγ,δ in immune cell function, we sought to determine whether PI3K inhibition altered antitumor immunity.Experimental Design: The effect of PI3K inhibition on tumor growth, metastasis, and antitumor immune response was characterized in mouse models utilizing orthotopic implants of 4T1 or PyMT mammary tumors into syngeneic or PI3Kγ-null mice, and patient-derived breast cancer xenografts in humanized mice. Tumor-infiltrating leukocytes were characterized by IHC and FACS analysis in BKM120 (30 mg/kg, every day) or vehicle-treated mice and PI3Kγnull versus PI3KγWT mice. On the basis of the finding that PI3K inhibition resulted in a more inflammatory tumor leukocyte infiltrate, the therapeutic efficacy of BKM120 (30 mg/kg, every day) and anti-PD1 (100 μg, twice weekly) was evaluated in PyMT tumor-bearing mice.Results: Our findings show that PI3K activity facilitates tumor growth and surprisingly restrains tumor immune surveillance. These activities could be partially suppressed by BKM120 or by genetic deletion of PI3Kγ in the host. The antitumor effect of PI3Kγ loss in host, but not tumor, was partially reversed by CD8+ T-cell depletion. Treatment with therapeutic doses of both BKM120 and antibody to PD-1 resulted in consistent inhibition of tumor growth compared with either agent alone.Conclusions: PI3K inhibition slows tumor growth, enhances antitumor immunity, and heightens susceptibility to immune checkpoint inhibitors. We propose that combining PI3K inhibition with anti-PD1 may be a viable therapeutic approach for triple-negative breast cancer. Clin Cancer Res; 23(13); 3371-84. ©2016 AACR.

nRGD modified lycobetaine and octreotide combination delivery system to overcome multiple barriers and enhance anti-glioma efficacy

For glioma as one of the most common and lethal primary brain tumors, the presence of BBB, BBTB, vasculogenic mimicry (VM) channels and tumor-associated macrophages (TAMs) are key biological barriers. Here, a novel drug delivery system which could efficiently deliver drugs to glioma by overcoming multi-barriers and increase antitumor efficacy through multi-therapeutic mechanisms was well developed. In this study, a multi-target peptide nRGD was used to transport across the BBB, mediate tumor penetration and target TAMs. Lycobetaine (LBT) was adopted to kill glioma cells and octreotide (OCT) was co-delivered to inhibit VM channels and prevent angiogenesis. LBT-OCT liposomes (LPs) showed controlled release profile in vitro, increased uptake efficiency, improved inhibitory effect against glioma cells and VM formation, and enhanced BBB-crossing capability. The median survival time of glioma-bearing mice administered with LBT-OCT LPs-nRGD was significantly longer than LBT-OCT LPs (P<0.01). Besides, nRGD achieved a stronger inhibitory effect against tumor associated macrophages (TAMs) compared to LPs-iRGD treatment groups in vivo. Thus, LPs-nRGD represented a promising versatile delivery platform for combination drug therapy in glioma treatment.

Serum protein profiling in diffuse large B-cell lymphoma

PURPOSE

The aim of this pilot study was to conduct a nontargeted exploratory proteomics profiling analysis on sera obtained from patients diagnosed with diffuse large B-cell lymphoma (DLBCL) with the goal of identifying disease-specific biomarkers.

EXPERIMENTAL DESIGN

Sera from 87 participants (57 chemotherapy-naïve diffuse DLBCL patients, 30 controls frequency-matched by age group and World Health Organization (WHO) BMI categories) that were part of a large San Francisco Bay Area case-control study of non-Hodgkin lymphoma were analyzed by liquid chromatography combined with tandem mass spectrometry.

RESULTS

Thirty-five proteins (p-adjusted <0.05) were identified as differentially abundant between the DLBCL patients at various disease stages as compared to the controls. Of these, five proteins were randomly selected for further confirmation by ELISA: adiponectin (AdipoQ), cluster of differentiation 14 (CD14), heparin sulfate proteoglycan core protein (HSPG2), extracellular matrix 1 (ECM1), and alpha-1-antichymotrypsin (ACT). These proteins were statistically significantly elevated by 68.8, 37.0, 61.6, 68.0, and 32.0%, respectively, in DLBCL patient sera as compared to controls.

CONCLUSION AND CLINICAL RELEVANCE

These preliminary data when combined with other cancer-related data regarding these proteins warrant continued research in clinical and large prospective studies to clarify the role for these biomarkers in DLBCL pathogenesis and/or prognosis.