Tumor-associated Microenvironment Research Articles

Improvement of Cancer Immunotherapy by Combining Molecular Targeted Therapy

In human cancer cells, a constitutive activation of MAPK, STAT3, β-catenin, and various other signaling pathways triggers multiple immunosuppressive cascades. These cascades result in the production of immunosuppressive molecules (e.g., TGF-β, IL-10, IL-6, VEGF, and CCL2) and induction of immunosuppressive immune cells (e.g., regulatory T cells, tolerogenic dendritic cells, and myeloid-derived suppressor cells). Consequently, immunosuppressive conditions are formed in tumor-associated microenvironments, including the tumor and sentinel lymph nodes. Some of these cancer-derived cytokines and chemokines impair immune cells and render them immunosuppressive via the activation of signaling molecules, such as STAT3, in the immune cells. Thus, administration of signal inhibitors may inhibit the multiple immunosuppressive cascades by acting simultaneously on both cancer and immune cells at the key regulatory points in the cancer-immune network. Since common signaling pathways are involved in manifestation of several hallmarks of cancer, including cancer cell proliferation/survival, invasion/metastasis, and immunosuppression, targeting these shared signaling pathways in combination with immunotherapy may be a promising strategy for cancer treatment.

Proteome Analysis Identified the PPARγ Ligand 15d-PGJ2 as a Novel Drug Inhibiting Melanoma Progression and Interfering with Tumor-Stroma Interaction

Peroxisome proliferator-activated receptors (PPARs) have been originally thought to be restricted to lipid metabolism or glucose homeostasis. Recently, evidence is growing that PPARγ ligands have inhibitory effects on tumor growth. To shed light on the potential therapeutic effects on melanoma we tested a panel of PPAR agonists on their ability to block tumor proliferation in vitro. Whereas ciglitazone, troglitazone and WY14643 showed moderate effects on proliferation, 15d-PGJ2 displayed profound anti-tumor activity on four different melanoma cell lines tested. Additionally, 15d-PGJ2 inhibited proliferation of tumor-associated fibroblasts and tube formation of endothelial cells. 15d-PGJ2 induced the tumor suppressor gene p21, a G2/M arrest and inhibited tumor cell migration. Shot gun proteome analysis in addition to 2D-gel electrophoresis and immunoprecipitation of A375 melanoma cells suggested that 15d-PGJ2 might exert its effects via modification and/or downregulation of Hsp-90 (heat shock protein 90) and several chaperones. Applying the recently established CPL/MUW database with a panel of defined classification signatures, we demonstrated a regulation of proteins involved in metastasis, transport or protein synthesis including paxillin, angio-associated migratory cell protein or matrix metalloproteinase-2 as confirmed by zymography. Our data revealed for the first time a profound effect of the single compound 15d-PGJ2 on melanoma cells in addition to the tumor-associated microenvironment suggesting synergistic therapeutic efficiency.

Suppression of tumor and metastasis progression through the scaffolding functions of SSeCKS/Gravin/AKAP12

Scaffolding proteins such as SSeCKS/Gravin/AKAP12 ("AKAP12") are thought to control oncogenic signaling pathways by regulating key mediators in a spatiotemporal manner. The downregulation of AKAP12 in many human cancers, often associated with promoter hypermethylation, or the loss of its locus at 6q24-25.2, correlates with progression to malignancy and metastasis. The forced re-expression of AKAP12 in cancer cell lines suppresses in vitro parameters of oncogenic growth, invasiveness, and cell motility through its ability to scaffold protein kinase C (PKC), F-actin, cyclins, Src, and phosphoinositides, and possibly through additional scaffolding domains for PKA, calmodulin, β1,4-galactosyltransferase-polypeptide-1, β2-adrenergic receptors, and cAMP-specific 3',5'-cyclic phosphodiesterase 4D. Moreover, AKAP12 re-expression in tumor models results in metastasis suppression through the inhibition of Src-regulated, VEGF-mediated neovascularization at distal sites. The current review will describe the emerging understanding of how AKAP12 regulates cellular senescence and oncogenic progression at the level of tumor cells and tumor-associated microenvironment via its multiple scaffolding functions.

TumorHoPe: A Database of Tumor Homing Peptides

BackgroundCancer is responsible for millions of immature deaths every year and is an economical burden on developing countries. One of the major challenges in the present era is to design drugs that can specifically target tumor cells not normal cells. In this context, tumor homing peptides have drawn much attention. These peptides are playing a vital role in delivering drugs in tumor tissues with high specificity. In order to provide service to scientific community, we have developed a database of tumor homing peptides called TumorHoPe.DescriptionTumorHoPe is a manually curated database of experimentally validated tumor homing peptides that specifically recognize tumor cells and tumor associated microenvironment, i.e., angiogenesis. These peptides were collected and compiled from published papers, patents and databases. Current release of TumorHoPe contains 744 peptides. Each entry provides comprehensive information of a peptide that includes its sequence, target tumor, target cell, techniques of identification, peptide receptor, etc. In addition, we have derived various types of information from these peptide sequences that include secondary/tertiary structure, amino acid composition, and physicochemical properties of peptides. Peptides in this database have been found to target different types of tumors that include breast, lung, prostate, melanoma, colon, etc. These peptides have some common motifs including RGD (Arg-Gly-Asp) and NGR (Asn-Gly-Arg) motifs, which specifically recognize tumor angiogenic markers. TumorHoPe has been integrated with many web-based tools like simple/complex search, database browsing and peptide mapping. These tools allow a user to search tumor homing peptides based on their amino acid composition, charge, polarity, hydrophobicity, etc.ConclusionTumorHoPe is a unique database of its kind, which provides comprehensive information about experimentally validated tumor homing peptides and their target cells. This database will be very useful in designing peptide-based drugs and drug-delivery system. It is freely available at http://crdd.osdd.net/raghava/tumorhope/.

Abstract 5423: Diet induced obesity, inflammation and prostate cancer progression in Hi-Myc mice

Abstract Obesity occurs when energy intake exceeds expenditure and is associated with increased risk and/or mortality rates for various types of cancers. In contrast, calorie restriction (CR) has been shown to act as a potent inhibitor of tumorigenesis in many tissues. We have recently reported that diet induced obesity (DIO) enhanced prostate cancer progression in the ventral prostate of the Hi-Myc mice (Blando et al, CAPR, 2011). Significant increases in inflammatory gene expression were observed as well as accumulation of inflammatory cells. In the current study, we have further investigated changes in inflammatory genes as well as cellular changes associated with DIO effects on prostate cancer progression in this mouse model. Initial studies were conducted to look at some of the cell populations that reside in the ventral prostate (VP) of Hi-Myc mice on the 30% CR, overweight control (AIN76A) and DIO diets (60% Kcal fat). Staining for perilipin (a lipid associated protein that marks adipocytes) revealed that adipocytes were restricted to the periphery of the VP of Hi-Myc mice on the 30% CR diet. In contrast, adipocytes could be seen infiltrating the VP of Hi-Myc mice on the overweight control diet. Notably, in mice on the DIO diet, many of the glands in the VP were completely surrounded by adipocytes. Additionally, we performed double staining for either perilipin and CD3 (T-lymphocytes) or perilipin and RM0029-11H3 (macrophages). Few if any inflammatory cells were seen in VP of Hi-Myc mice on the 30% CR diet. In contrast, adipocytes and inflammatory cells (both T-cells and macrophages) were seen in close proximity to adipocytes that had infiltrated into the VP in both the overweight control and DIO diet groups. This was particularly evident in Hi-Myc mice on the DIO diet. In addition, we have also stained sections of VP from Hi-Myc mice on the different diets for both the IL-23 receptor (IL-23R) and Cox-2. IL-23R expression was dramatically upregulated in the epithelial cells of the VP from Hi-Myc mice on the DIO compared to the other diet groups. These data suggest that IL-23 may play a role not only in driving further inflammatory cell activation (e.g., TH17+/ CD4+ T-cells) but also have direct effects on prostate epithelial cells that facilitate prostate cancer progression. Cox-2 expression was also dramatically upregulated in VP of Hi-Myc on the DIO diet. This finding is consistent with the high level of NFkB activation seen in prostate tissues for the same mice and diet group. Thus, Cox-2 and subsequent generation of arachidonic metabolites may also play a role in the effects of DIO on prostate cancer progression in Hi-Myc mice. Collectively, changes in the levels of IL-23R and COX-2 and the elevated presence of inflammatory cells together with changes in the adipose tissue, suggest that the tumor associated microenvironment may play a key role in DIO effects on prostate cancer progression in Hi-Myc mice. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5423. doi:1538-7445.AM2012-5423

Abstract IA26: Role of the microenvironment in prostate cancer progression and resistance

Abstract The improved understanding of prostate cancer progression and resistance has led to the development and application of therapies that have prolonged the survival of patients with advanced cancer. These therapies have been based on newly identified mechanisms of microtubule poisons, tumor-associated bone microenvironment, and an appreciation that the transition from endocrine to intracrine (autocrine/paracrine) androgen signaling is implicated in castrate resistance (Geller et al, Nelson et al). Investigators have hypothesized that the efficacy of microtubule poisons has been in part attributed to their ability to interrupt androgen signaling in prostate cancer (Gianakakou et al, Kyprianou et al). The role of Src family kinases, RANKL, and FGF, as well as the recent observation that C-met/VEGR 2 inhibitor may alter the progression of bone metastases, provide confidence in the relevance of experimental observations to human prostate cancer (Gallick et al, Fizzazi et al, Navone et al). Furthermore, the perplexing finding that PSMA and PSA vaccines prolong the survival of patients with prostate cancer without causing objective responses or measurably delaying time to progression add to the enthusiasm for the outcome, but have created new challenges (Kantoff et al). Evidence that individual agents with diverse mechanisms prolong survival is encouraging; however, most patients experience disease progression. This has provided the impetus for understanding mechanism(s) of resistance and the interaction between interventions. Development of predictive markers based on the understanding of the mechanisms of response and resistance will form the foundation for a marker-driven combinatorial treatment strategy. Recent advances in the ability to sample prostate cancer tissue at metastatic sites and to develop tumor grafts have partially overcome the limitations of previous model systems and the difficulties of accessing relevant tumor samples (Navone et al, Efstathiou et al). These tools have been used to identify subsets of cancers driven by biologically relevant differences (Aparicio et al). Identification of aggressive variants of prostate cancer in clinical and murine systems have led to prioritization and development of cyclin-dependent and Aurora kinases as targets for this subset of patients (Beltran et al, Sankar et al, Tzelepi et al). Furthermore, the characterization of cancers in model systems and clinically while on treatment with the potent antiandrogen MDV 3100 and the androgen biosynthesis inhibitor abiraterone acetate have identified CYP 17 expression, presence of steroid hormones at picogram levels, and intense nuclear AR expression as components of a predictive signature. If validated, the signature may be used to identify subsets of patients likely to benefit from further modulation of AR signaling. Trial designs that account for the complex therapeutic environment in which drugs are delivered have been developed, deployed, and their feasibility established (Thall et al , Millikan et al). Incorporating the coclinical trials strategy promises to accelerate development of combinatorial treatment (Pandolfi et al). Taken together, advances in the basic understanding of cancer progression and resistance, new agent development, modeling, and improved trial design establish a foundation for effective marker-driven therapy that optimally integrates microenvironment-targeted therapies, immunotherapy, and microtubule poisons for patients with advanced prostate cancer. Citation Format: Christopher J. Logothetis. Role of the microenvironment in prostate cancer progression and resistance [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA26.

Tumor-Associated Macrophages in the Cutaneous SCC Microenvironment Are Heterogeneously Activated

Tumor-Associated Macrophages in the Cutaneous SCC Microenvironment Are Heterogeneously Activated

Abstract 1426: Identification of secretory stromal gene signature of the ovarian tumor microenvironment and implications for ovarian cancer progression

Abstract Ovarian cancer the deadliest gynecologic disease and despite the significant role of the tumor-associated stroma in cancer progression, little research has been done on the specific role of the tumor-associated stromal microenvironment on ovarian cancer progression. Our objective was to identify genes that are differentially regulated in the stromal component of high-grade late-stage serous ovarian cancer and illustrate direct and specific effects of their differential expression on ovarian cancer progression. Microarray analysis performed on RNA isolated from 10 microdissected normal ovarian fibroblasts, and the epithelial and stromal component of 16 high-grade late stage serous ovarian cancers revealed more than 40 secreted proteins that are overexpressed more than 5 fold by cancer-associated fibroblasts (CAFs) exclusively. Quantitative RT-PCR validated the overexpression of several genes, including sFRP2, by the CAFs. Clinical data correlated stromal sFRP2 overexpression with poorer overall survival and chemoresistance in patients with high-grade late stage serous ovarian cancer, suggesting that sFRP2 promotes ovarian cancer progression. In vitro functional studies illustrate increased ovarian cancer cell proliferation rates in response to recombinant sFRP2 as well as CAF-conditioned medium and pathway analysis via transcription-reporter assays revealed that recombinant sFRP2 signals through the NFκB and Wnt pathways in ovarian cancer cells, both of which affect cell growth. While not affecting cell proliferation, recombinant sFRP2 increased endothelial signaling to the NFAT pathway, which affects endothelial tubal branching. These results were corroborated in vivo such that microenvironments expressing higher levels of sFRP2 exhibited significantly higher microvessel density compared with microenvironments with lower sFRP2 expression. Our results illustrate a direct and specific signaling linkage from the tumor microenvironment to tumor cells and endothelial cells that contributes to tumor progression. In this case, sFRP2 exhibited significant influence on characteristics of tumor progression (i.e. tumor proliferation, microvessel morphology) suggesting that other differentially expressed genes identified by the microarray in CAFs may also play significant roles in this process. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1426.

Peptide-Mediated Liposomal Drug Delivery System Targeting Tumor Blood Vessels in Anticancer Therapy

Solid tumors are known to recruit new blood vessels to support their growth. Therefore, unique molecules expressed on tumor endothelial cells can function as targets for the antiangiogenic therapy of cancer. Current efforts are focusing on developing therapeutic agents capable of specifically targeting cancer cells and tumor-associated microenvironments including tumor blood vessels. These therapies hold the promise of high efficacy and low toxicity. One recognized strategy for improving the therapeutic effectiveness of conventional chemotherapeutics is to encapsulate anticancer drugs into targeting liposomes that bind to the cell surface receptors expressed on tumor-associated endothelial cells. These anti-angiogenic drug delivery systems could be used to target both tumor blood vessels as well as the tumor cells, themselves. This article reviews the mechanisms and advantages of various present and potential methods using peptide-conjugated liposomes to specifically destroy tumor blood vessels in anticancer therapy.

Principles of Modular Tumor Therapy

Nature is interwoven with communication and is represented and reproduced through communication acts. The central question is how may multimodal modularly acting and less toxic therapy approaches, defined as modular therapies, induce an objective response or even a continuous complete remission, although single stimulatory or inhibitingly acting drugs neither exert mono-activity in the respective metastatic tumor type nor are they directed to potentially ‘tumor-specific’ targets. Modularity in the present context is a formal pragmatic communicative systems concept, describing the degree to which systems objects (cells, pathways etc.) may be communicatively separated in a virtual continuum, and recombined and rededicated to alter validity and denotation of communication processes in the tumor. Intentional knowledge, discharging in reductionist therapies, disregards the risk-absorbing background knowledge of the tumor’s living world including the holistic communication processes, which we rely on in every therapy. At first, this knowledge constitutes the validity of informative intercellular processes, which is the prerequisite for therapeutic success. All communication-relevant steps, such as intentions, understandings, and the appreciation of messages, may be modulated simultaneously, even with a high grade of specificity. Thus, modular therapy approaches including risk-absorbing and validity-modifying background knowledge may overcome reductionist idealizations. Modular therapies show modular events assembled by the tumor’s living world as an additional evolution-constituting dimension. This way, modular knowledge may be acquired from the environment, either incidentally or constitutionally. The new communicatively defined modular coherency of environment, i.e. the tumor-associated microenvironment, and tumor cells open novel ways for the scientific community in ‘translational medicine’.

Combined Vascular Endothelial Growth Factor Receptor/Epidermal Growth Factor Receptor Blockade with Chemotherapy for Treatment of Local, Uterine, and Metastatic Soft Tissue Sarcoma

Soft tissue sarcoma (STS) is a rare heterogeneous malignancy. Overall survival has been stagnant for decades, primarily because systemic therapies are ineffective versus metastases, the leading cause of STS lethality. Consequently, we examined whether tyrosine kinase receptors active in STS growth signaling might be blockable and whether multireceptor blockade might synergize with low-dose STS chemotherapy by therapeutically affecting STS cells and their associated microenvironment. Vandetanib (AstraZenca), a tyrosine kinase inhibitor of vascular endothelial growth factor receptor 2 and epidermal growth factor receptor, was evaluated alone and with chemotherapy in vitro and in vivo in three human STS nude mouse xenograft models of different STS locations (muscle, uterus, lung), stages (primary, metastatic), and subtypes (leiomyosarcoma, fibrosarcoma, uterine sarcoma: luciferase-expressing MES-SA human uterine sarcoma cells surgically implanted into uterine muscularis with bioluminescence tumor growth assessment; developed by us). In vitro, human STS cells were sensitive to vandetanib. Vandetanib alone and with chemotherapy statistically significantly inhibited leiomyosarcoma local growth and fibrosarcoma lung metastasis. Direct injection of MES-SA into nude mice uterine muscularis resulted in high tumor take (88%), whereas s.c. injection resulted in no growth, suggesting microenvironmental tumor growth modulation. Vandetanib alone and with chemotherapy statistically significantly inhibited uterine sarcoma growth. In all models, vandetanib induced increased apoptosis, decreased tumor cell proliferation, and decreased angiogenesis. Vandetanib has antitumor effects against human STS subtypes in vitro and in vivo, where it also affects the tumor-associated microenvironment. Given the urgent need for better systemic approaches to STS, clinical trials evaluating vandetanib, perhaps with low-dose chemotherapy, seem warranted.

Human CD4+ T cells present within the microenvironment of human lung tumors are mobilized by the local and sustained release of IL-12 to kill tumors in situ by indirect effects of IFN-gamma.

By implanting nondisrupted pieces of human lung tumor biopsy tissues into SCID mice, it has been possible to establish viable grafts of the tumor, as well as the tumor-associated microenvironment, including inflammatory cells, fibroblasts, tumor vasculature, and the extracellular matrix. Using this xenograft model, we have evaluated and characterized the effects of a local and sustained release of human rIL-12 (rhIL-12) from biodegradable microspheres. In response to rhIL-12, the human CD45+ inflammatory cells present within the xenograft mediate the suppression or the complete arrest of tumor growth in SCID mice. Analysis of the cellular events reveals that human CD4+ and CD8+ T cells are induced by rhIL-12 to produce and secrete IFN-gamma. Serum levels of human IFN-gamma in mice bearing rhIL-12-treated tumor xenografts correlate directly with the degree of tumor suppression, while neutralizing Abs to human IFN-gamma abrogate the IL-12-mediated tumor suppression. Gene expression profiling of tumors responding to intratumoral rhIL-12 demonstrates an up-regulation of IFN-gamma and IFN-gamma-dependent genes not observed in control-treated tumors. Genes encoding a number of proinflammatory cytokines, chemokines (and their receptors), adhesion molecules, activation markers, and the inducible NO synthase are up-regulated following the introduction of rhIL-12, while genes associated with tumor growth, angiogenesis, and metastasis are decreased in expression. NO contributes to the tumor killing because an inhibitor of inducible NO synthase prevents IL-12-induced tumor suppression. Cell depletion studies reveal that the IL-12-induced tumor suppression, IFN-gamma production, and the associated changes in gene expression are all dependent upon CD4+ T cells.