Type III TGF-β receptor downregulation generates an immunotolerant tumor microenvironment

The mechanisms tumor cells utilize to evade the host's immune system

The immune system plays an essential role in the tumor progression; not only can it inhibit tumor growth but it can also promote tumor growth by establishing a favorable environment. Tumor cells utilize several strategies to evade the host's immune system, including expression of immunosuppressive molecules such as PD-L1, IDO and siglec-9. In addition, tumor cells not only regulate the recruitment and development of immunosuppressive forces to influence the tumor microenvironment but also shift the phenotype and function of normal immune cells from a possibly anti-tumor state to a pro-tumor state. As a result, tumor cells evade the host's immune system, leading to metastasis and/or recurrent disease.

Does Porcine Oocytes Maturation in Vitro is Regulated by Genes Involved in Transforming Growth Factor Beta Receptor Signaling Pathway?

The oocyte growth and development in follicular environment are substantially accompanied by surrounding somatic cumulus (CCs) and granulosa cells (GCs). During these processes, the mammalian gametes reach full maturational stage and may be further successfully fertilized by single spermatozoon. These unique mechanisms are regulated by expression of clusters of genes and their biochemical signaling pathways.

In this article we described differential expression pattern of transforming growth factor beta (TGFB) gene superfamily in porcine oocytes before and after in vitro maturation (IVM).

We performed Affymetrix® microarray assays to investigate the TGFB-related genes expression profile in porcine immature oocytes and gametes cultured for 44h in vitro.

In results we found 419 different genes, 379 genes with lower expression, and 40 genes characterized by increased RNA profile. Moreover, significant up-regulation of 6 genes belonging to TGFB signaling pathway such as: TGFBR3, SMAD4, FOS, KLF10, ID1, MAP3K1 in immature porcine oocytes (before IVM), was also observed.

It may be suggested that genes involved in TGFB-related signaling pathway are substantially regulated before IVM. Furthermore, these genes may play a significant role during early stages of nuclear and/or cytoplasmic porcine oocytes maturation. The investigated transcripts may be also recommended as the markers of oocytes maturational capability in pigs.

Regulation of Innate and Adaptive Immunity by TGFβ

Immune regulation by cytokines is crucial in maintaining immune homeostasis, promoting responses to infection, resolving inflammation, and promoting immunological memory. Additionally, cytokine responses drive pathology in immune-mediated disease. A crucial cytokine in the regulation of all aspects of an immune response is transforming growth factor beta (TGFβ). Although best known as a crucial regulator of T cell responses, TGFβ plays a vital role in regulating responses mediated by virtually every innate and adaptive immune cell, including dendritic cells, B cells, NK cells, innate lymphoid cells, and granulocytes. Here, we review our current knowledge of how TGFβ regulates the immune system, highlighting the multifunctional nature of TGFβ and how its function can change depending on location and context of action.

Heparin-binding epidermal growth factor-like growth factor promotes neuroblastoma differentiation

High-risk neuroblastoma is characterized by undifferentiated neuroblasts and low schwannian stroma content. The tumor stroma contributes to the suppression of tumor growth by releasing soluble factors that promote neuroblast differentiation. Here we identify heparin-binding epidermal growth factor-like growth factor (HBEGF) as a potent prodifferentiating factor in neuroblastoma. HBEGF mRNA expression is decreased in human neuroblastoma tumors compared with benign tumors, with loss correlating with decreased survival. HBEGF protein is expressed only in stromal compartments of human neuroblastoma specimens, with tissue from high-stage disease containing very little stroma or HBEGF expression. In 3 human neuroblastoma cell lines (SK-N-AS, SK-N-BE2, and SH-SY5Y), soluble HBEGF is sufficient to promote neuroblast differentiation and decrease proliferation. Heparan sulfate proteoglycans and heparin derivatives further enhance HBEGF-induced differentiation by forming a complex with the epidermal growth factor receptor, leading to activation of the ERK1/2 and STAT3 pathways and up-regulation of the inhibitor of DNA binding transcription factor. These data support a role for loss of HBEGF in the neuroblastoma tumor microenvironment in neuroblastoma pathogenesis.-Gaviglio, A. L., Knelson, E. H., Blobe, G. C. Heparin-binding epidermal growth factor-like growth factor promotes neuroblastoma differentiation.

TβRIII Expression in Human Breast Cancer Stroma and the Role of Soluble TβRIII in Breast Cancer Associated Fibroblasts

The TGF-β pathway plays a major role in tumor progression through regulation of epithelial and stromal cell signaling. Dysfunction of the pathway can lead to carcinoma progression and metastasis. To gain insight into the stromal role of the TGF-β pathway in breast cancer, we performed laser capture microdissection (LCM) from breast cancer patients and reduction mammoplasty patients. Microdissected tumor stroma and normal breast stroma were examined for gene expression. Expression of the TGF-β type III receptor (TGFBR3) was greatly decreased in the tumor stroma compared to control healthy breast tissue. These results demonstrated a 44-fold decrease in TGFBR3 mRNA in tumor stroma in comparison to control tissue. We investigated publicly available databases, and have identified that TGFBR3 mRNA levels are decreased in tumor stroma. We next investigated fibroblast cell lines derived from cancerous and normal breast tissue and found that in addition to mRNA levels, TβRIII protein levels were significantly reduced. Having previously identified that cancer-associated fibroblasts secrete greater levels of tumor promoting cytokines, we investigated the consequences of soluble-TβRIII (sTβRIII) on fibroblasts. Fibroblast conditioned medium was analyzed for 102 human secreted cytokines and distinct changes in response to sTβRIII were observed. Next, we used the fibroblast-conditioned medium to stimulate human monocyte cell line THP-1. These results indicate a distinct transcriptional response depending on sTβRIII treatment and whether it was derived from normal or cancerous breast tissue. We conclude that the effect of TβRIII has distinct roles not only in cancer-associated fibroblasts but that sTβRIII has distinct paracrine functions in the tumor microenvironment.

Surface Expression of TGFβ Docking Receptor GARP Promotes Oncogenesis and Immune Tolerance in Breast Cancer

GARP encoded by the Lrrc32 gene is the cell surface docking receptor for latent TGFβ, which is expressed naturally by platelets and regulatory T cells (Treg). Although Lrrc32 is amplified frequently in breast cancer, the expression and relevant functions of GARP in cancer have not been explored. Here, we report that GARP exerts oncogenic effects, promoting immune tolerance by enriching and activating latent TGFβ in the tumor microenvironment. We found that human breast, lung, and colon cancers expressed GARP aberrantly. In genetic studies in normal mammary gland epithelial and carcinoma cells, GARP expression increased TGFβ bioactivity and promoted malignant transformation in immunodeficient mice. In breast carcinoma-bearing mice that were immunocompetent, GARP overexpression promoted Foxp3⁺ Treg activity, which in turn contributed to enhancing cancer progression and metastasis. Notably, administration of a GARP-specific mAb limited metastasis in an orthotopic model of human breast cancer. Overall, these results define the oncogenic effects of the GARP-TGFβ axis in the tumor microenvironment and suggest mechanisms that might be exploited for diagnostic and therapeutic purposes. Cancer Res; 76(24); 7106-17. ©2016 AACR.

Immune evasion pathways and the design of dendritic cell-based cancer vaccines

Emerging data is suggesting that the process of dendritic cell (DC) tolerization is an important step in tumorigenesis. Our understanding of the networks within the tumor microenvironment that functionally tolerize DC function is evolving while methods for genetically manipulating DC populations in situ continue to develop. A more intimate understanding of the paracrine signaling pathways which mediate immune evasion by subverting DC function promises to provide novel strategies for improving the clinical efficacy of DC-based cancer vaccines. This will likely require a better understanding of both the antigen expression profile and the immune evasion network of the tumor and its associated stromal tissues.

Immunogenic, cellular, and angiogenic drivers of tumor dormancy--a melanoma view

In tumor cells, the ability to maintain viability over long time periods without proliferation is referred to as a state of dormancy. Maintenance of dormancy is controlled by numerous cellular and environmental factors, from immune surveillance and tumor-stroma interaction to intracellular signaling. Interference of dormancy (to an 'awaken' state) is associated with reduced response to therapy, resulting in relapse or in metastatic burst. Thus, maintaining a dormant state should prolong therapeutic responses and delay metastasis. Technical obstacles in studying tumor dormancy have limited our understanding of underlying mechanisms and hampered our ability to target dormant cells. In this review, we summarize the progress of research in the field of immunogenic, angiogenic, and cellular dormancy in diverse malignancies with particular attention to our current understanding in melanoma.

Matters of context guide future research in TGFβ superfamily signaling

The highly conserved wiring of the SMAD-dependent transforming growth factor β (TGFβ) superfamily signaling pathway has been mapped over the last 20 years after molecular discovery of its component parts. Numerous alternative TGFβ-activated signaling pathways that elicit SMAD-independent biological responses also exist. However, the molecular mechanisms responsible for the renowned context dependency of TGFβ signaling output remains an active and often confounding area of research, providing a prototype relevant to regulation of other signaling pathways. Highlighting discoveries presented at the 9th FASEB meeting, The TGFβ Superfamily: Signaling in Development and Disease (July 12-17th 2015 in Snowmass, Colorado), this Review outlines research into the rich contextual nature of TGFβ signaling output and offers clues for therapeutic advances.

Melanoma-Derived Wnt5a Promotes Local Dendritic-Cell Expression of IDO and Immunotolerance: Opportunities for Pharmacologic Enhancement of Immunotherapy

The β-catenin signaling pathway has been demonstrated to promote the development of a tolerogenic dendritic cell (DC) population capable of driving regulatory T-cell (Treg) differentiation. Further studies have implicated tolerogenic DCs in promoting carcinogenesis in preclinical models. The molecular mechanisms underlying the establishment of immune tolerance by this DC population are poorly understood, and the methods by which developing cancers can co-opt this pathway to subvert immune surveillance are currently unknown. This work demonstrates that melanoma-derived Wnt5a ligand upregulates the durable expression and activity of the indoleamine 2,3-dioxygenase-1 (IDO) enzyme by local DCs in a manner that depends upon the β-catenin signaling pathway. These data indicate that Wnt5a-conditioned DCs promote the differentiation of Tregs in an IDO-dependent manner, and that this process serves to suppress melanoma immune surveillance. We further show that the genetic silencing of the PORCN membrane-bound O-acyl transferase, which is necessary for melanoma Wnt ligand secretion, enhances antitumor T-cell immunity, and that the pharmacologic inhibition of this enzyme synergistically suppresses melanoma progression when combined with anti-CTLA-4 antibody therapy. Finally, our data suggest that β-catenin signaling activity, based on a target gene expression profile that includes IDO in human sentinel lymph node-derived DCs, is associated with melanoma disease burden and diminished progression-free survival. This work implicates the Wnt-β-catenin signaling pathway as a novel therapeutic target in the melanoma immune microenvironment and demonstrates the potential impact of manipulating DC function as a strategy for optimizing tumor immunotherapy.

Role of indoleamine 2,3-dioxygenase in health and disease

IDO1 (indoleamine 2,3-dioxygenase 1) is a member of a unique class of mammalian haem dioxygenases that catalyse the oxidative catabolism of the least-abundant essential amino acid, L-Trp (L-tryptophan), along the kynurenine pathway. Significant increases in knowledge have been recently gained with respect to understanding the fundamental biochemistry of IDO1 including its catalytic reaction mechanism, the scope of enzyme reactions it catalyses, the biochemical mechanisms controlling IDO1 expression and enzyme activity, and the discovery of enzyme inhibitors. Major advances in understanding the roles of IDO1 in physiology and disease have also been realised. IDO1 is recognised as a prominent immune regulatory enzyme capable of modulating immune cell activation status and phenotype via several molecular mechanisms including enzyme-dependent deprivation of L-Trp and its conversion into the aryl hydrocarbon receptor ligand kynurenine and other bioactive kynurenine pathway metabolites, or non-enzymatic cell signalling actions involving tyrosine phosphorylation of IDO1. Through these different modes of biochemical signalling, IDO1 regulates certain physiological functions (e.g. pregnancy) and modulates the pathogenesis and severity of diverse conditions including chronic inflammation, infectious disease, allergic and autoimmune disorders, transplantation, neuropathology and cancer. In the present review, we detail the current understanding of IDO1’s catalytic actions and the biochemical mechanisms regulating IDO1 expression and activity. We also discuss the biological functions of IDO1 with a focus on the enzyme's immune-modulatory function, its medical implications in diverse pathological settings and its utility as a therapeutic target.

Development and validation of a novel platform-independent metastasis signature in human breast cancer

Purpose

The molecular drivers of metastasis in breast cancer are not well understood. Therefore, we sought to identify the biological processes underlying distant progression and define a prognostic signature for metastatic potential in breast cancer.

Experimental design

In vivo screening for metastases was performed using Chick Chorioallantoic Membrane assays in 21 preclinical breast cancer models. Expressed genes associated with metastatic potential were identified using high-throughput analysis. Correlations with biological function were determined using the Database for Annotation, Visualization and Integrated Discovery.

Results

We identified a broad range of metastatic potential that was independent of intrinsic breast cancer subtypes. 146 genes were significantly associated with metastasis progression and were linked to cancer-related biological functions, including cell migration/adhesion, Jak-STAT, TGF-beta, and Wnt signaling. These genes were used to develop a platform-independent gene expression signature (M-Sig), which was trained and subsequently validated on 5 independent cohorts totaling nearly 1800 breast cancer patients with all p-values < 0.005 and hazard ratios ranging from approximately 2.5 to 3. On multivariate analysis accounting for standard clinicopathologic prognostic variables, M-Sig remained the strongest prognostic factor for metastatic progression, with p-values < 0.001 and hazard ratios > 2 in three different cohorts.

Conclusion

M-Sig is strongly prognostic for metastatic progression, and may provide clinical utility in combination with treatment prediction tools to better guide patient care. In addition, the platform-independent nature of the signature makes it an excellent research tool as it can be directly applied onto existing, and future, datasets.

The balance of cell surface and soluble type III TGF-β receptor regulates BMP signaling in normal and cancerous mammary epithelial cells

Bone morphogenetic proteins (BMPs) are members of the TGF-β superfamily that are over-expressed in breast cancer, with context dependent effects on breast cancer pathogenesis. The type III TGF-β receptor (TβRIII) mediates BMP signaling. While TβRIII expression is lost during breast cancer progression, the role of TβRIII in regulating BMP signaling in normal mammary epithelium and breast cancer cells has not been examined. Restoring TβRIII expression in a 4T1 murine syngeneic model of breast cancer suppressed Smad1/5/8 phosphorylation and inhibited the expression of the BMP transcriptional targets, Id1 and Smad6, in vivo. Similarly, restoring TβRIII expression in human breast cancer cell lines or treatment with sTβRIII inhibited BMP-induced Smad1/5/8 phosphorylation and BMP-stimulated migration and invasion. In normal mammary epithelial cells, shRNA-mediated silencing of TβRIII, TβRIII over-expression, or treatment with sTβRIII inhibited BMP-mediated phosphorylation of Smad1/5/8 and BMP induced migration. Inhibition of TβRIII shedding through treatment with TAPI-2 or expression of a non-shedding TβRIII mutant rescued TβRIII mediated inhibition of BMP induced Smad1/5/8 phosphorylation and BMP induced migration and/or invasion in both in normal mammary epithelial cells and breast cancer cells. Conversely, expression of a TβRIII mutant, which exhibited increased shedding, significantly reduced BMP-mediated Smad1/5/8 phosphorylation, migration, and invasion. These data demonstrate that TβRIII regulates BMP-mediated signaling and biological effects, primarily through the ligand sequestration effects of sTβRIII in normal and cancerous mammary epithelial cells and suggest that the ratio of membrane bound versus sTβRIII plays an important role in mediating these effects.

Fibulin-3 is a novel TGF-β pathway inhibitor in the breast cancer microenvironment

TGF-β is an important regulator of breast cancer progression. However, how the breast cancer microenvironment regulates TGF-β signaling during breast cancer progression remains largely unknown. Here, we identified fibulin-3 as a secreted protein in the breast cancer microenvironment, which efficiently inhibits TGF-β signaling in both breast cancer cells and endothelial cells. Mechanistically, fibulin-3 interacts with the type I TGF-β receptor (TβRI) to block TGF-β induced complex formation of TβRI with the type II TGF-β receptor (TβRII) and subsequent downstream TGF-β signaling. Fibulin-3 expression decreases during breast cancer progression, with low fibulin-3 levels correlating with a poorer prognosis. Functionally, high fibulin-3 levels inhibited TGF-β-induced EMT, migration, invasion and endothelial permeability, while loss of fibulin-3 expression/function promoted these TGF-β-mediated effects. Further, restoring fibulin-3 expression in breast cancer cells inhibited TGF-β signaling, breast cancer cell EMT, invasion and metastasis in vivo. These studies provide a novel mechanism for how TGF-β signaling is regulated by the tumor microenvironment, and provide insight into targeting the TGF-β signaling pathway in human breast cancer patients.

Loss of GDF10/BMP3b as a prognostic marker collaborates with TGFBR3 to enhance chemotherapy resistance and epithelial-mesenchymal transition in oral squamous cell carcinoma

Growth differentiation factor-10 (GDF10), commonly referred as BMP3b, is a member of the transforming growth factor-β (TGF-β) superfamily. GDF10/BMP3b has been considered as a tumor suppressor, however, little is known about the molecular mechanism of its roles in tumor suppression in oral cancer. Clinical significance of GDF10 downregulation in oral squamous cell carcinoma (OSCC) was evaluated using three independent cohorts of OSCC patients. The molecular mechanisms of GDF10 in the suppression of cell survival, cell migration/invasion and epithelial-mesenchymal transition (EMT) were investigated by using oral cancer cell lines. The present study shows that GDF10 is downregulated during oral carcinogenesis, and GDF10 expression is also an independent risk factor for overall survival of OSCC patients. Overexpression of GDF10 attenuates cell proliferation, transformation, migration/invasion, and EMT. GDF10-inhibited EMT is mediated by ERK signaling but not by typical TGF-β signaling. In addition, overexpression of GDF10 promotes DNA damage-induced apoptosis and sensitizes the response to all-trans retinoic acid (ATRA) and camptothecin (CPT). Intriguingly, the expression of GDF10 is induced by type III TGF-β receptor (TGFBR3) through TGF-β-SMAD2/3 signaling. Our findings suggest that TGFBR3 is an upstream activator of GDF10 expression and they share the same signaling to inhibit EMT and migration/invasion. These results support that GDF10 acts as a hinge to collaborate with TGFBR3 in the transition of EMT-MET program. Taken together, we illustrated the clinical significance and the molecular mechanisms of tumor-suppressive GDF10 in OSCC.

Proteolytic control of TGF-β co-receptor activity by BMP-1/tolloid-like proteases revealed by quantitative iTRAQ proteomics

The metalloproteinase BMP-1 (bone morphogenetic protein-1) plays a major role in the control of extracellular matrix (ECM) assembly and growth factor activation. Most of the growth factors activated by BMP-1 are members of the TGF-β superfamily known to regulate multiple biological processes including embryonic development, wound healing, inflammation and tumor progression. In this study, we used an iTRAQ (isobaric tags for relative and absolute quantification)-based quantitative proteomic approach to reveal the release of proteolytic fragments from the cell surface or the ECM by BMP-1. Thirty-eight extracellular proteins were found in significantly higher or lower amounts in the conditioned medium of HT1080 cells overexpressing BMP-1 and thus, could be considered as candidate substrates. Strikingly, three of these new candidates (betaglycan, CD109 and neuropilin-1) were TGF-β co-receptors, also acting as antagonists when released from the cell surface, and were chosen for further substrate validation. Betaglycan and CD109 proved to be directly cleaved by BMP-1 and the corresponding cleavage sites were extensively characterized using a new mass spectrometry approach. Furthermore, we could show that the ability of betaglycan and CD109 to interact with TGF-β was altered after cleavage by BMP-1, leading to increased and prolonged SMAD2 phosphorylation in BMP-1-overexpressing cells. Betaglycan processing was also observed in primary corneal keratocytes, indicating a general and novel mechanism by which BMP-1 directly affects signaling by controlling TGF-β co-receptor activity. The proteomic data have been submitted to ProteomeXchange with the identifier PXD000786 and doi: 10.6019/PXD000786 .

Transforming growth factor β-mediated suppression of antitumor T cells requires FoxP1 transcription factor expression

Tumor-reactive T cells become unresponsive in advanced tumors. Here we have characterized a common mechanism of T cell unresponsiveness in cancer driven by the upregulation of the transcription factor Forkhead box protein P1 (Foxp1), which prevents CD8⁺ T cells from proliferating and upregulating Granzyme-B and interferon-γ in response to tumor antigens. Accordingly, Foxp1-deficient lymphocytes induced rejection of incurable tumors and promoted protection against tumor rechallenge. Mechanistically, Foxp1 interacted with the transcription factors Smad2 and Smad3 in preactivated CD8⁺ T cells in response to microenvironmental transforming growth factor-β (TGF-β), and was essential for its suppressive activity. Therefore, Smad2 and Smad3-mediated c-Myc repression requires Foxp1 expression in T cells. Furthermore, Foxp1 directly mediated TGF-β-induced c-Jun transcriptional repression, which abrogated T cell activity. Our results unveil a fundamental mechanism of T cell unresponsiveness different from anergy or exhaustion, driven by TGF-β signaling on tumor-associated lymphocytes undergoing Foxp1-dependent transcriptional regulation.

Early Carcinogenesis Involves the Establishment of Immune Privilege via Intrinsic and Extrinsic Regulation of Indoleamine 2,3-dioxygenase-1: Translational Implications in Cancer Immunotherapy

Although prolonged genetic pressure has been conjectured to be necessary for the eventual development of tumor immune evasion mechanisms, recent work is demonstrating that early genetic mutations are capable of moonlighting as both intrinsic and extrinsic modulators of the tumor immune microenvironment. The indoleamine 2,3-dioxygenase-1 (IDO) immunoregulatory enzyme is emerging as a key player in tumor-mediated immune tolerance. While loss of the tumor suppressor, BIN-1, and the over-expression of cyclooxygenase-2 have been implicated in intrinsic regulation of IDO, recent findings have demonstrated the loss of TβRIII and the upregulation of Wnt5a by developing cancers to play a role in the extrinsic control of IDO activity by local dendritic cell populations residing within tumor and tumor-draining lymph node tissues. Together, these genetic changes are capable of modulating paracrine signaling pathways in the early stages of carcinogenesis to establish a site of immune privilege by promoting the differentiation and activation of local regulatory T cells. Additional investigation of these immune evasion pathways promises to provide opportunities for the development of novel strategies to synergistically enhance the efficacy of the evolving class of T cell-targeted "checkpoint" inhibitors.

Transforming growth factor β-mediated suppression of antitumor T cells requires FoxP1 transcription factor expression

Tumor-reactive T cells become unresponsive in advanced tumors. Here we have characterized a common mechanism of T cell unresponsiveness in cancer driven by the upregulation of the transcription factor Forkhead box protein P1 (Foxp1), which prevents CD8⁺ T cells from proliferating and upregulating Granzyme-B and interferon-γ in response to tumor antigens. Accordingly, Foxp1-deficient lymphocytes induced rejection of incurable tumors and promoted protection against tumor rechallenge. Mechanistically, Foxp1 interacted with the transcription factors Smad2 and Smad3 in preactivated CD8⁺ T cells in response to microenvironmental transforming growth factor-β (TGF-β), and was essential for its suppressive activity. Therefore, Smad2 and Smad3-mediated c-Myc repression requires Foxp1 expression in T cells. Furthermore, Foxp1 directly mediated TGF-β-induced c-Jun transcriptional repression, which abrogated T cell activity. Our results unveil a fundamental mechanism of T cell unresponsiveness different from anergy or exhaustion, driven by TGF-β signaling on tumor-associated lymphocytes undergoing Foxp1-dependent transcriptional regulation.

Harnessing the immune system for the treatment of breast cancer

Standard treatment options for breast cancer include surgery, chemotherapy, radiation, and targeted therapies, such as adjuvant hormonal therapy and monoclonal antibodies. Recently, the recognition that chronic inflammation in the tumor microenvironment promotes tumor growth and survival during different stages of breast cancer development has led to the development of novel immunotherapies. Several immunotherapeutic strategies have been studied both preclinically and clinically and already have been shown to enhance the efficacy of conventional treatment modalities. Therefore, therapies targeting the immune system may represent a promising next-generation approach for the treatment of breast cancers. This review will discuss recent findings that elucidate the roles of suppressive immune cells and proinflammatory cytokines and chemokines in the tumor-promoting microenvironment, and the most current immunotherapeutic strategies in breast cancer.

A multicenter phase I dose escalation trial to evaluate safety and tolerability of intra-arterial temozolomide for patients with advanced extremity melanoma using normothermic isolated limb infusion

BACKGROUND

L-phenylalanine mustard (LPAM) has been the standard for use in regional chemotherapy (RC) for unresectable in-transit melanoma. Preclinical data demonstrated that regional temozolomide (TMZ) may be more effective.

METHODS

Patients with AJCC Stage IIIB or IIIC extremity melanoma who failed previous LPAM-based RC were treated with TMZ via isolated limb infusion (ILI) according to a modified accelerated titration design. Drug pharmacokinetic (PK) analysis, tumor gene expression, methylation status of the O6-methylguanine methyltransferase (MGMT) promoter, and MGMT expression were evaluated. Primary objectives were to (1) determine dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of TMZ via ILI and (2) explore biomarker correlates of response.

RESULTS

28 patients completed treatment over 2.5 years at 3 institutions. 19 patients were treated at the MTD defined as 3,200 mg/m(2) [multiplied by 0.09 (arm), 0.18 (leg)]. Two of five patients had DLTs at the 3,600 mg/m(2) level while only grade 1 (n = 15) and grade 2 (n = 4) clinical toxicities occurred at the MTD. At 3-month post-ILI, 10.5 % (2/19) had CR, 5.3 % (1/19) had PR, 15.8 % (3/19) had SD, and 68.4 % (13/19) had PD. Neither PK parameters of TMZ nor MGMT levels were associated with response or toxicity.

CONCLUSION

In this first ever use of intra-arterial TMZ in ILI for melanoma, the MTD was determined. While we could not define a marker for TMZ response, the minimal toxicity of TMZ ILI may allow for repeated treatments to increase the response rate as well as clarify the role of MGMT expression.

Characterization of type III TGF-β receptor expression in invasive breast carcinomas: a potential new marker and target for triple negative breast cancer

Invasive breast carcinomas are heterogeneous and exhibit distinct molecular features and biological behavior. Understanding the underlying molecular events that promote breast cancer progression is necessary to improve treatment and prognostication. TGF-β receptor III (TBR3) is a member of the TGF-β signaling pathway, with functions in cell proliferation and migration in malignancies, including breast cancer. Recent studies propose that TBR3 may function as a tumor suppressor and that its loss may correlate with disease progression. However, there are limited data on the expression of TBR3 in breast cancer in relationship to tumor type, hormonal receptor status and HER-2/neu, and patient outcome. In this study, we investigated the expression of TBR3 in a cohort of 205 primary invasive breast carcinomas in tissue microarrays (TMAs), with comprehensive clinical, pathological and follow- up information. Sections were stained for TBR3 and evaluated for intensity of reactivity based on a 4-tiered scoring system (1 to 4; TBR3 low = scores 1-2; TBR3 high = scores 3-4). Of the 205 invasive carcinomas, 123 were luminal type (95 type A, 28 type B), 8 were HER-2 type, and 62 were triple negative (TN). TBR3 was high in 112 (55 %) and low in 93 (45 %) cases. Low TBR3 was associated with higher histological grade and worse disease free and overall survival, all features of biologically aggressive breast carcinomas. TBR3 was significantly associated with the subtype of breast cancer, as low TBR3 was detected in 95 % of TN compared to 22 % of luminal tumors (p < 0.0001). We discovered a significant association between low TBR3 protein expression, TN breast cancer phenotype, and disease progression. These data suggest that TBR3 loss might be linked to the development of TN breast cancers and pave the way to investigating whether restoring TBR3 function may be a therapeutic strategy against TN breast carcinomas.

Ectodomain shedding of TβRIII is required for TβRIII-mediated suppression of TGF-β signaling and breast cancer migration and invasion

The type III TGF-β receptor (TβRIII) undergoes ectodomain shedding, with surface TβRIII enhancing and soluble TβRIII inhibiting TGF-β signaling. TβRIII mutants with impaired or enhanced shedding are used to demonstrate that the ratio of soluble to membrane-bound TβRIII regulates TβRIII/TGF-β–mediated signaling and biology in vitro and in vivo.

The type III transforming growth factor β (TGF-β) receptor (TβRIII), also known as betaglycan, is the most abundantly expressed TGF-β receptor. TβRIII suppresses breast cancer progression by inhibiting migration, invasion, metastasis, and angiogenesis. TβRIII binds TGF-β ligands, with membrane-bound TβRIII presenting ligand to enhance TGF-β signaling. However, TβRIII can also undergo ectodomain shedding, releasing soluble TβRIII, which binds and sequesters ligand to inhibit downstream signaling. To investigate the relative contributions of soluble and membrane-bound TβRIII on TGF-β signaling and breast cancer biology, we defined TβRIII mutants with impaired (ΔShed-TβRIII) or enhanced ectodomain shedding (SS-TβRIII). Inhibiting ectodomain shedding of TβRIII increased TGF-β responsiveness and abrogated TβRIII's ability to inhibit breast cancer cell migration and invasion. Conversely, expressing SS-TβRIII, which increased soluble TβRIII production, decreased TGF-β signaling and increased TβRIII-mediated inhibition of breast cancer cell migration and invasion. Of importance, SS-TβRIII–mediated increases in soluble TβRIII production also reduced breast cancer metastasis in vivo. Taken together, these studies suggest that the ratio of soluble TβRIII to membrane-bound TβRIII is an important determinant for regulation of TβRIII- and TGF-β–mediated signaling and biology.

Stromal heparan sulfate differentiates neuroblasts to suppress neuroblastoma growth

Neuroblastoma prognosis is dependent on both the differentiation state and stromal content of the tumor. Neuroblastoma tumor stroma is thought to suppress neuroblast growth via release of soluble differentiating factors. Here, we identified critical growth-limiting components of the differentiating stroma secretome and designed a potential therapeutic strategy based on their central mechanism of action. We demonstrated that expression of heparan sulfate proteoglycans (HSPGs), including TβRIII, GPC1, GPC3, SDC3, and SDC4, is low in neuroblasts and high in the Schwannian stroma. Evaluation of neuroblastoma patient microarray data revealed an association between TGFBR3, GPC1, and SDC3 expression and improved prognosis. Treatment of neuroblastoma cell lines with soluble HSPGs promoted neuroblast differentiation via FGFR1 and ERK phosphorylation, leading to upregulation of the transcription factor inhibitor of DNA binding 1 (ID1). HSPGs also enhanced FGF2-dependent differentiation, and the anticoagulant heparin had a similar effect, leading to decreased neuroblast proliferation. Dissection of individual sulfation sites identified 2-O, 3-O-desulfated heparin (ODSH) as a differentiating agent, and treatment of orthotopic xenograft models with ODSH suppressed tumor growth and metastasis without anticoagulation. These studies support heparan sulfate signaling intermediates as prognostic and therapeutic neuroblastoma biomarkers and demonstrate that tumor stroma biology can inform the design of targeted molecular therapeutics.

Role of TGF-β receptor III localization in polarity and breast cancer progression

The majority of breast cancers originate from the highly polarized luminal epithelial cells lining the breast ducts. However, cell polarity is often lost during breast cancer progression. The type III transforming growth factor-β cell surface receptor (TβRIII) functions as a suppressor of breast cancer progression and also regulates the process of epithelial-to-mesenchymal transition (EMT), a consequence of which is the loss of cell polarity. Many cell surface proteins exhibit polarized expression, being targeted specifically to the apical or basolateral domains. Here we demonstrate that TβRIII is basolaterally localized in polarized breast epithelial cells and that disruption of the basolateral targeting of TβRIII through a single amino acid mutation of proline 826 in the cytosolic domain results in global loss of cell polarity through enhanced EMT. In addition, the mistargeting of TβRIII results in enhanced proliferation, migration, and invasion in vitro and enhanced tumor formation and invasion in an in vivo mouse model of breast carcinoma. These results suggest that proper localization of TβRIII is critical for maintenance of epithelial cell polarity and phenotype and expand the mechanisms by which TβRIII prevents breast cancer initiation and progression.

Chitosan-based thermoreversible hydrogel as an in vitro tumor microenvironment for testing breast cancer therapies

Breast cancer is a major health problem for women worldwide. Although in vitro culture of established breast cancer cell lines is the most widely used model for preclinical assessment, it poorly represents the behavior of breast cancers in vivo. Acceleration of the development of effective therapeutic strategies requires a cost-efficient in vitro model that can more accurately resemble the in vivo tumor microenvironment. Here, we report the use of a thermoreversible poly(ethylene glycol)-g-chitosan hydrogel (PCgel) as an in vitro breast cancer model. We hypothesized that PCgel could provide a tumor microenvironment that promotes cultured cancer cells to a more malignant phenotype with drug and immune resistance. Traditional tissue culture plates and Matrigel were applied as controls in our studies. In vitro cellular proliferation and morphology, the secretion of angiogenesis-related growth factors and cytokines, and drug and immune resistance were assessed. Our results show that PCgel cultures promoted tumor aggregate formation, increased secretion of various angiogenesis- and metastasis-related growth factors and cytokines, and increased tumor cell resistance to chemotherapeutic drugs and immunotherapeutic T cells. This PCgel platform may offer a valuable strategy to bridge the gap between standard in vitro and costly animal studies for a wide variety of experimental designs.

Heparan sulfate signaling in cancer

Heparan sulfate (HS) is a biopolymer consisting of variably sulfated repeating disaccharide units. The anticoagulant heparin is a highly sulfated intracellular variant of HS. HS has demonstrated roles in embryonic development, homeostasis, and human disease via non-covalent interactions with numerous cellular proteins, including growth factors and their receptors. HS can function as a co-receptor by enhancing receptor-complex formation. In other contexts, HS disrupts signaling complexes or serves as a ligand sink. The effects of HS on growth factor signaling are tightly regulated by the actions of sulfyltransferases, sulfatases, and heparanases. HS has important emerging roles in oncogenesis, and heparin derivatives represent potential therapeutic strategies for human cancers. Here we review recent insights into HS signaling in tumor proliferation, angiogenesis, metastasis, and differentiation. A cancer-specific understanding of HS signaling could uncover potential therapeutic targets in this highly actionable signaling network.

Immunotherapy following regional chemotherapy treatment of advanced extremity melanoma

PURPOSE

Following regional chemotherapy (RC) for melanoma, approximately 75 % of patients will progress. The role of immunotherapy after RC has not been well established.

METHODS

A prospective, single-institution database of 243 patients with in-transit melanoma (1995-2013) was queried for patients who had progression of disease after RC with melphalan and subsequently received systemic immunotherapy. Fifteen patients received IL-2 only, 12 received ipilimumab only, and 6 received IL-2 followed by ipilimumab. Fisher's exact test was used to determine if there was a difference in number of complete responders after immunotherapy.

RESULTS

With IL-2 alone, all patients progressed. After ipilimumab alone, three patients had a complete response and nine had progressive disease. Six additional patients received IL-2 first then ipilimumab. All six progressed on IL-2 but three went on to have a complete response to ipilimumab while three progressed. The use of ipilimumab at any time in patients who progressed after RC was associated with higher rate of complete response compared to use of IL-2 alone (33 vs. 0 %; p = 0.021).

CONCLUSIONS

Patients with progression after regional therapy for melanoma may benefit from immunologic therapy. In this group of patients, immune checkpoint blockade with ipilimumab has a higher complete response rate than T cell stimulation with IL-2, with no complete responders in the IL-2 only group. Furthermore, the complete response rate for ipilimumab in our cohort is higher than reported response rates in the literature for ipilimumab alone, suggesting that the effects of immunotherapy may be bolstered by previous regional treatment.

Differential expression of bitter taste receptors in non-cancerous breast epithelial and breast cancer cells

The human bitter taste receptors (T2Rs) are chemosensory receptors that belong to the G protein-coupled receptor superfamily. T2Rs are present on the surface of oral and many extra-oral cells. In humans 25 T2Rs are present, and these are activated by hundreds of chemical molecules of diverse structure. Previous studies have shown that many bitter compounds including chloroquine, quinidine, bitter melon extract and cucurbitacins B and E inhibit tumor growth and induce apoptosis in cancer cells. However, the existence of T2Rs in cancer cell is not yet elucidated. In this report using quantitative (q)-PCR and flow cytometry, we characterized the expression of T2R1, T2R4, T2R10, T2R38 and T2R49 in the highly metastatic breast cancer cell line MDA-MB-231, poorly metastatic cell line MCF-7, and non-cancerous mammary epithelial cell line MCF-10A. Among the 5 T2Rs analyzed by qPCR and flow cytometry, T2R4 is expressed at 40-70% in mammary epithelial cells in comparison to commonly used breast cancer marker proteins, estrogen receptor and E-cadherin. Interestingly, the expression of T2R4 was downregulated in breast cancer cells. An increase in intracellular calcium mobilization was observed after the application of bitter agonists, quinine, dextromethorphan, and phenylthiocarbamide that are specific for some of the 5 T2Rs. This suggests that the endogenous T2Rs expressed in these cells are functional. Taken together, our novel findings suggest that T2Rs are differentially expressed in mammary epithelial cells, with some T2Rs downregulated in breast cancer cells.

A systems biology approach identifies effective tumor-stroma common targets for oral squamous cell carcinoma

The complex interactions between cancer cells and their surrounding stromal microenvironment play important roles in tumor initiation and progression and represent viable targets for therapeutic intervention. Here, we propose a concept of common target perturbation (CTP). CTP acts simultaneously on the same target in both the tumor and its stroma that generates a bilateral disruption for potentially improved cancer therapy. To employ this concept, we designed a systems biology strategy by combining experiment and computation to identify potential common target. Through progressive cycles of identification, TGF-β receptor III (TβRIII) is found as an epithelial-mesenchymal common target in oral squamous cell carcinoma. Simultaneous perturbation of TβRIII in the oral cancerous epithelial cells and their adjacent carcinoma-associated fibroblasts effectively inhibits tumor growth in vivo, and shows superiority to the unilateral perturbation of TβRIII in either cell type alone. This study indicates the strong potential to identify therapeutic targets by considering cancer cells and their adjacent stroma simultaneously. The CTP concept combined with our common target discovery strategy provides a framework for future targeted cancer combinatorial therapies.

TGFβ and matrix-regulated epithelial to mesenchymal transition

BACKGROUND

The progression of cancer through stages that guide a benign hyperplastic epithelial tissue towards a fully malignant and metastatic carcinoma, is driven by genetic and microenvironmental factors that remodel the tissue architecture. The concept of epithelial-mesenchymal transition (EMT) has evolved to emphasize the importance of plastic changes in tissue architecture, and the cross-communication of tumor cells with various cells in the stroma and with specific molecules in the extracellular matrix (ECM).

SCOPE OF THE REVIEW

Among the multitude of ECM-embedded cytokines and the regulatory potential of ECM molecules, this article focuses on the cytokine transforming growth factor β (TGFβ) and the glycosaminoglycan hyaluronan, and their roles in cancer biology and EMT. For brevity, we concentrate our effort on breast cancer.

MAJOR CONCLUSIONS

Both normal and abnormal TGFβ signaling can be detected in carcinoma and stromal cells, and TGFβ-induced EMT requires the expression of hyaluronan synthase 2 (HAS2). Correspondingly, hyaluronan is a major constituent of tumor ECM and aberrant levels of both hyaluronan and TGFβ are thought to promote a wounding reaction to the local tissue homeostasis. The link between EMT and metastasis also involves the mesenchymal-epithelial transition (MET). ECM components, signaling networks, regulatory non-coding RNAs and epigenetic mechanisms form the network of regulation during EMT-MET.

GENERAL SIGNIFICANCE

Understanding the mechanism that controls epithelial plasticity in the mammary gland promises the development of valuable biomarkers for the prognosis of breast cancer progression and even provides new ideas for a more integrative therapeutic approach against disease. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Pathological mobilization and activities of dendritic cells in tumor-bearing hosts: challenges and opportunities for immunotherapy of cancer

A common characteristic of solid tumors is the pathological recruitment of immunosuppressive myeloid cells, which in certain tumors includes dendritic cells (DCs). DCs are of particular interest in the field of cancer immunotherapy because they induce potent and highly specific anti-tumor immune responses, particularly in the early phase of tumorigenesis. However, as tumors progress, these cells can be transformed into regulatory cells that contribute to an immunosuppressive microenvironment favoring tumor growth. Therefore, controlling DC phenotype has the potential to elicit effective anti-tumor responses while simultaneously weakening the tumor’s ability to protect itself from immune attack. This review focuses on the dual nature of DCs in the tumor microenvironment, the regulation of DC phenotype, and the prospect of modifying DCs in situ as a novel immunotherapeutic approach.

Isolated limb infusion as a model to test new agents to treat metastatic melanoma

The limb model of in-transit disease can expand our understanding of treating melanoma because of the ease of obtaining tissue biopsies for correlative studies and the availability of preclinical animal models that allow validation of novel therapeutic strategies. This review will focus on regional therapy for in-transit melanoma as a platform to investigate novel therapeutic approaches to improve regional disease control, and help us develop insights to more rationally design systemic therapy trials.