ComplexEye: a multi-lens array microscope for high-throughput embedded immune cell migration analysis

Autonomous migration is essential for the function of immune cells such as neutrophils and plays an important role in numerous diseases. The ability to routinely measure or target it would offer a wealth of clinical applications. Video microscopy of live cells is ideal for migration analysis, but cannot be performed at sufficiently high-throughput (HT). Here we introduce ComplexEye, an array microscope with 16 independent aberration-corrected glass lenses spaced at the pitch of a 96-well plate to produce high-resolution movies of migrating cells. With the system, we enable HT migration analysis of immune cells in 96- and 384-well plates with very energy-efficient performance. We demonstrate that the system can measure multiple clinical samples simultaneously. Furthermore, we screen 1000 compounds and identify 17 modifiers of migration in human neutrophils in just 4 days, a task that requires 60-times longer with a conventional video microscope. ComplexEye thus opens the field of phenotypic HT migration screens and enables routine migration analysis for the clinical setting.

Interleukin 17 signaling supports clinical benefit of dual CTLA-4 and PD-1 checkpoint inhibition in melanoma

Recent studies suggest that BRAFV600-mutated melanomas in particular respond to dual anti-programmed cell death protein 1 (PD-1) and anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) immune checkpoint inhibition (ICI). Here we identified an over-representation of interleukin (IL)-17-type 17 helper T (TH17) gene expression signatures (GES) in BRAFV600-mutated tumors. Moreover, high baseline IL-17 GES consistently predicted clinical responses in dual-ICI-treated patient cohorts but not in mono anti-CTLA-4 or anti-PD-1 ICI cohorts. High IL-17 GES corresponded to tumor infiltration with T cells and neutrophils. Accordingly, high neutrophil infiltration correlated with clinical response specifically to dual ICI, and tumor-associated neutrophils also showed strong IL-17-TH17 pathway activity and T cell activation capacity. Both the blockade of IL-17A and the depletion of neutrophils impaired dual-ICI response and decreased T cell activation. Finally, high IL-17A levels in the blood of patients with melanoma indicated a higher global TH17 cytokine profile preceding clinical response to dual ICI but not to anti-PD-1 monotherapy, suggesting a future role as a biomarker for patient stratification.

Active Remodeling of Capillary Endothelium via Cancer Cell-Derived MMP9 Promotes Metastatic Brain Colonization

Crossing the blood-brain barrier is a crucial, rate-limiting step of brain metastasis. Understanding of the mechanisms of cancer cell extravasation from brain microcapillaries is limited as the underlying cellular and molecular processes cannot be adequately investigated using in vitro models and endpoint in vivo experiments. Using ultrastructural and functional imaging, we demonstrate that dynamic changes of activated brain microcapillaries promote the mandatory first steps of brain colonization. Successful extravasation of arrested cancer cells occurred when adjacent capillary endothelial cells (EC) entered into a distinct remodeling process. After extravasation, capillary loops were formed, which was characteristic of aggressive metastatic growth. Upon cancer cell arrest in brain microcapillaries, matrix-metalloprotease 9 (MMP9) was expressed. Inhibition of MMP2/9 and genetic perturbation of MMP9 in cancer cells, but not the host, reduced EC projections, extravasation, and brain metastasis outgrowth. These findings establish an active role of ECs in the process of cancer cell extravasation, facilitated by cross-talk between the two cell types. This extends our understanding of how host cells can contribute to brain metastasis formation and how to prevent it.

SIGNIFICANCE

Tracking single extravasating cancer cells using multimodal correlative microscopy uncovers a brain seeding mechanism involving endothelial remodeling driven by cancer cell-derived MMP9, which might enable the development of approaches to prevent brain metastasis. See related commentary by McCarty, p. 1167.

Glucocorticoid activation by HSD11B1 limits T cell-driven interferon signaling and response to PD-1 blockade in melanoma

BACKGROUND

Immune responses against tumors are subject to negative feedback regulation. Immune checkpoint inhibitors (ICIs) blocking Programmed cell death protein 1 (PD-1), a receptor expressed on T cells, or its ligand PD-L1 have significantly improved the treatment of cancer, in particular malignant melanoma. Nevertheless, responses and durability are variables, suggesting that additional critical negative feedback mechanisms exist and need to be targeted to improve therapeutic efficacy.

METHODS

We used different syngeneic melanoma mouse models and performed PD-1 blockade to identify novel mechanisms of negative immune regulation. Genetic gain-of-function and loss-of-function approaches as well as small molecule inhibitor applications were used for target validation in our melanoma models. We analyzed mouse melanoma tissues from treated and untreated mice by RNA-seq, immunofluorescence and flow cytometry to detect changes in pathway activities and immune cell composition of the tumor microenvironment. We analyzed tissue sections of patients with melanoma by immunohistochemistry as well as publicly available single-cell RNA-seq data and correlated target expression with clinical responses to ICIs.

RESULTS

Here, we identified 11-beta-hydroxysteroid dehydrogenase-1 (HSD11B1), an enzyme that converts inert glucocorticoids into active forms in tissues, as negative feedback mechanism in response to T cell immunotherapies. Glucocorticoids are potent suppressors of immune responses. HSD11B1 was expressed in different cellular compartments of melanomas, most notably myeloid cells but also T cells and melanoma cells. Enforced expression of HSD11B1 in mouse melanomas limited the efficacy of PD-1 blockade, whereas small molecule HSD11B1 inhibitors improved responses in a CD8+ T cell-dependent manner. Mechanistically, HSD11B1 inhibition in combination with PD-1 blockade augmented the production of interferon-γ by T cells. Interferon pathway activation correlated with sensitivity to PD-1 blockade linked to anti-proliferative effects on melanoma cells. Furthermore, high levels of HSD11B1, predominantly expressed by tumor-associated macrophages, were associated with poor responses to ICI therapy in two independent cohorts of patients with advanced melanomas analyzed by different methods (scRNA-seq, immunohistochemistry).

CONCLUSION

As HSD11B1 inhibitors are in the focus of drug development for metabolic diseases, our data suggest a drug repurposing strategy combining HSD11B1 inhibitors with ICIs to improve melanoma immunotherapy. Furthermore, our work also delineated potential caveats emphasizing the need for careful patient stratification.

Rapid and fully automated blood vasculature analysis in 3D light-sheet image volumes of different organs

Light-sheet fluorescence microscopy (LSFM) can produce high-resolution tomograms of tissue vasculature with high accuracy. However, data processing and analysis is laborious due to the size of the datasets. Here, we introduce VesselExpress, an automated software that reliably analyzes six characteristic vascular network parameters including vessel diameter in LSFM data on average computing hardware. VesselExpress is ∼100 times faster than other existing vessel analysis tools, requires no user interaction, and integrates batch processing and parallelization. Employing an innovative dual Frangi filter approach, we show that obesity induces a large-scale modulation of brain vasculature in mice and that seven other major organs differ strongly in their 3D vascular makeup. Hence, VesselExpress transforms LSFM from an observational to an analytical working tool.

Abstract 2487: Distinct venous brain vessels provide structures for T lymphocyte recruitment to brain tumors in mouse models of intracranial melanoma

Immune checkpoint therapy has demonstrated potential for the treatment of brain metastases, but the mechanisms of lymphocyte recruitment to brain tumors are poorly understood. To monitor T cell infiltration and brain tumor growth in vivo in real time, we performed intravital microscopy of adoptively transferred and endogenous T cells in mouse models of intracranial melanoma. By spatio-temporal analysis of T cell infiltration dynamics in brain tumors we could identify a distinct type of venous blood vessels in the tumor vicinity, “peritumoral venous vessels” (PVVs). Intraluminal T cell attachment and T cell extravasation was increased at PVVs compared to intratumoral vessels. Moreover, PVVs were characterized by high perivascular T cell density, high T cell motility parameters and high expression of ICAM-1. PVVs were specifically exploited for the recruitment of T cells to melanoma brain tumors, whereas alternative T cell routes via brain structures such as brain capillaries, intratumoral blood vessels and parasagittal regions were not observed. Immune checkpoint inhibition increased T cell motility in the brain, facilitating the advance from PVV to tumor, which resulted in intracranial tumor growth inhibition. Our findings describe a distinct mechanism by which the immune system targets melanoma brain tumors, and, potentially, other intracranial pathologies.

Citation Format: Julia M. Messmer, Manuel Piechutta, Varun Venkataramani, Chanté Mayer, Anna S. Berghoff, Daniel Hinze, Michael Hölzel, Iris Helfrich, Dirk Schadendorf, Wolfgang Wick, Matthia A. Karreman, Frank Winkler. Distinct venous brain vessels provide structures for T lymphocyte recruitment to brain tumors in mouse models of intracranial melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2487.

Persister state-directed transitioning and vulnerability in melanoma

Melanoma is a highly plastic tumor characterized by dynamic interconversion of different cell identities depending on the biological context. Melanoma cells with high expression of the H3K4 demethylase KDM5B (JARID1B) rest in a slow-cycling, yet reversible persister state. Over time, KDM5Bhigh cells can promote rapid tumor repopulation with equilibrated KDM5B expression heterogeneity. The cellular identity of KDM5Bhigh persister cells has not been studied so far, missing an important cell state-directed treatment opportunity in melanoma. Here, we have established a doxycycline-titratable system for genetic induction of permanent intratumor expression of KDM5B and screened for chemical agents that phenocopy this effect. Transcriptional profiling and cell functional assays confirmed that the dihydropyridine 2-phenoxyethyl 4-(2-fluorophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxylate (termed Cpd1) supports high KDM5B expression and directs melanoma cells towards differentiation along the melanocytic lineage and to cell cycle-arrest. The high KDM5B state additionally prevents cell proliferation through negative regulation of cytokinetic abscission. Moreover, treatment with Cpd1 promoted the expression of the melanocyte-specific tyrosinase gene specifically sensitizing melanoma cells for the tyrosinase-processed antifolate prodrug 3-O-(3,4,5-trimethoxybenzoyl)-(-)-epicatechin (TMECG). In summary, our study provides proof-of-concept for a dual hit strategy in melanoma, in which persister state-directed transitioning limits tumor plasticity and primes melanoma cells towards lineage-specific elimination.

Impact of radiotherapy and sequencing of systemic therapy on survival outcomes in melanoma patients with previously untreated brain metastasis: a multicenter DeCOG study on 450 patients from the prospective skin cancer registry ADOREG

BACKGROUND

Despite of various therapeutic strategies, treatment of patients with melanoma brain metastasis (MBM) still is a major challenge. This study aimed at investigating the impact of type and sequence of immune checkpoint blockade (ICB) and targeted therapy (TT), radiotherapy, and surgery on the survival outcome of patients with MBM.

METHOD

We assessed data of 450 patients collected within the prospective multicenter real-world skin cancer registry ADOREG who were diagnosed with MBM before start of the first non-adjuvant systemic therapy. Study endpoints were progression-free survival (PFS) and overall survival (OS).

RESULTS

Of 450 MBM patients, 175 (38.9%) received CTLA-4+PD-1 ICB, 161 (35.8%) PD-1 ICB, and 114 (25.3%) BRAF+MEK TT as first-line treatment. Additional to systemic therapy, 67.3% of the patients received radiotherapy (stereotactic radiosurgery (SRS); conventional radiotherapy (CRT)) and 24.4% had surgery of MBM. 199 patients (42.2%) received a second-line systemic therapy. Multivariate Cox regression analysis revealed the application of radiotherapy (HR for SRS: 0.213, 95% CI 0.094 to 0.485, p<0.001; HR for CRT: 0.424, 95% CI 0.210 to 0.855, p=0.016), maximal size of brain metastases (HR for MBM >1 cm: 1.977, 95% CI 1.117 to 3.500, p=0.019), age (HR for age >65 years: 1.802, 95% CI 1.016 to 3.197, p=0.044), and ECOG performance status (HR for ECOG ≥2: HR: 2.615, 95% CI 1.024 to 6.676, p=0.044) as independent prognostic factors of OS on first-line therapy. The type of first-line therapy (ICB vs TT) was not independently prognostic. As second-line therapy BRAF+MEK showed the best survival outcome compared with ICB and other therapies (HR for CTLA-4+PD-1 compared with BRAF+MEK: 13.964, 95% CI 3.6 to 54.4, p<0.001; for PD-1 vs BRAF+MEK: 4.587 95% CI 1.3 to 16.8, p=0.022 for OS). Regarding therapy sequencing, patients treated with ICB as first-line therapy and BRAF+MEK as second-line therapy showed an improved OS (HR for CTLA-4+PD-1 followed by BRAF+MEK: 0.370, 95% CI 0.157 to 0.934, p=0.035; HR for PD-1 followed by BRAF+MEK: 0.290, 95% CI 0.092 to 0.918, p=0.035) compared with patients starting with BRAF+MEK in first-line therapy. There was no significant survival difference when comparing first-line therapy with CTLA-4+PD-1 ICB with PD-1 ICB.

CONCLUSIONS

In patients with MBM, the addition of radiotherapy resulted in a favorable OS on systemic therapy. In BRAF-mutated MBM patients, ICB as first-line therapy and BRAF+MEK as second-line therapy were associated with a significantly prolonged OS.

SIRT1-mediated deacetylation of FOXO3a transcription factor supports pro-angiogenic activity of interferon-deficient tumor-associated neutrophils

Angiogenesis plays an important role during tumor growth and metastasis. We could previously show that Type I interferon (IFN)-deficient tumor-associated neutrophils (TANs) show strong pro-angiogenic activity, and stimulate tumor angiogenesis and growth. However, the exact mechanism responsible for their pro-angiogenic shift is not clear. Here, we set out to delineate the molecular mechanism and factors regulating pro-angiogenic properties of neutrophils in the context of Type I IFN availability. We demonstrate that neutrophils from IFN-deficient (Ifnar1^-/- ) mice efficiently release pro-angiogenic factors, such as VEGF, MMP9 or BV8, and thus significantly support the vascular normalization of tumors by increasing the maturation of perivascular cells. Mechanistically, we could show here that the expression of pro-angiogenic factors in neutrophils is controlled by the transcription factor forkhead box protein O3a (FOXO3a), which activity depends on its post-translational modifications, such as deacetylation or phosphorylation. In TANs isolated from Ifnar1^-/- mice, we observe significantly elevated SIRT1, resulting in SIRT1-mediated deacetylation of FOXO3a, its nuclear retention and activation. Activated FOXO3a supports in turn the transcription of pro-angiogenic genes in TANs. In the absence of SIRT1, or after its inhibition in neutrophils, elevated kinase MEK/ERK and PI3K/AKT activity is observed, leading to FOXO3a phosphorylation, cytoplasmic transfer and inactivation. In summary, we have found that FOXO3a is a key transcription factor controlling the angiogenic switch of neutrophils. Post-translational FOXO3a modifications regulate its transcriptional activity and, as a result, the expression of pro-angiogenic factors supporting development of vascular network in growing tumors. Therefore, targeting FOXO3a activity could provide a novel strategy of antiangiogenic targeted therapy for cancer.

Sequence-Selective Covalent CaaX-Box Receptors Prevent Farnesylation of Oncogenic Ras Proteins and Impact MAPK/PI3 K Signaling

Oncogenic Ras proteins are implicated in the most common life-threatening cancers. Despite intense research over the past two decades, the progress towards small-molecule inhibitors has been limited. One reason for this failure is that Ras proteins interact with their effectors only via protein-protein interactions, which are notoriously difficult to address with small organic molecules. Herein we describe an alternative strategy, which prevents farnesylation and subsequent membrane insertion, a prerequisite for the activation of Ras proteins. Our approach is based on sequence-selective supramolecular receptors which bind to the C-terminal farnesyl transferase recognition unit of Ras and Rheb proteins and covalently modify the essential cysteine in the so-called CaaX-box.

Targeting early stages of cardiotoxicity from anti-PD1 immune checkpoint inhibitor therapy

AIMS

Cardiac immune-related adverse events (irAEs) from immune checkpoint inhibition (ICI) targeting programmed death 1 (PD1) are of growing concern. Once cardiac irAEs become clinically manifest, fatality rates are high. Cardio-oncology aims to prevent detrimental effects before manifestation of severe complications by targeting early pathological changes. We therefore aimed to investigate early consequences of PD1 inhibition for cardiac integrity to prevent the development of overt cardiac disease.

METHODS AND RESULTS

We investigated cardiac-specific consequences from anti-PD1 therapy in a combined biochemical and in vivo phenotyping approach. Mouse hearts showed broad expression of the ligand PDL1 on cardiac endothelial cells as a main mediator of immune-crosstalk. Using a novel melanoma mouse model, we assessed that anti-PD1 therapy promoted myocardial infiltration with CD4+ and CD8+ T cells, the latter being markedly activated. Left ventricular (LV) function was impaired during pharmacological stress, as shown by pressure-volume catheterization. This was associated with a dysregulated myocardial metabolism, including the proteome and the lipidome. Analogous to the experimental approach, in patients with metastatic melanoma (n = 7) receiving anti-PD1 therapy, LV function in response to stress was impaired under therapy. Finally, we identified that blockade of tumour necrosis factor alpha (TNFα) preserved LV function without attenuating the anti-cancer efficacy of anti-PD1 therapy.

CONCLUSIONS

Anti-PD1 therapy induces a disruption of cardiac immune homeostasis leading to early impairment of myocardial functional integrity, with potential prognostic effects on the growing number of treated patients. Blockade of TNFα may serve as an approach to prevent the manifestation of ICI-related cardiotoxicity.

Integrative Genomic Analyses of Patient-Matched Intracranial and Extracranial Metastases Reveal a Novel Brain-Specific Landscape of Genetic Variants in Driver Genes of Malignant Melanoma

BACKGROUND

Development of brain metastases in advanced melanoma patients is a frequent event that limits patients' quality of life and survival. Despite recent insights into melanoma genetics, systematic analyses of genetic alterations in melanoma brain metastasis formation are lacking. Moreover, whether brain metastases harbor distinct genetic alterations beyond those observed at different anatomic sites of the same patient remains unknown.

EXPERIMENTAL DESIGN AND RESULTS

In our study, 54 intracranial and 18 corresponding extracranial melanoma metastases were analyzed for mutations using targeted next generation sequencing of 29 recurrently mutated driver genes in melanoma. In 11 of 16 paired samples, we detected nucleotide modifications in brain metastases that were absent in matched metastases at extracranial sites. Moreover, we identified novel genetic variants in ARID1A, ARID2, SMARCA4 and BAP1, genes that have not been linked to brain metastases before; albeit most frequent mutations were found in ARID1A, ARID2 and BRAF. Conclusion: Our data provide new insights into the genetic landscape of intracranial melanoma metastases supporting a branched evolution model of metastasis formation.

Tumor necrosis factor alpha blockade prevents immune checkpoint inhibitor therapy-related cardiotoxicity

Background

Increasing use of immune checkpoint inhibitor (ICI) therapy has recently been associated with latent left ventricular dysfunction as a common cardiotoxic side effect during early therapy. Considering the potential impact on morbidity and mortality, strategies to prevent ICI-related cardiotoxicity are urgently needed, but established immunosuppressive measures prevent the anti-tumor effect of the ICI therapy, thereby limiting its applicability to severe, life-threatening cases. Recently, tumor necrosis factor alpha (TNFα) blockade was shown to prevent ICI-related gut toxicity while preserving, or even enhancing, anti-tumor efficacy.

Purpose

This study aims to investigate a cardioprotective effect of TNFα blockade during anti programmed death 1 (PD1) ICI therapy in a preclinical model as a basis for a potential new, preventive therapeutic approach for ICI-related cardiotoxicity.

Methods

A melanoma mouse model was established as the basis to study PD1 blocking therapy and protective measures in a preclinical setting. Mice were subcutaneously transplanted with a syngeneic melanoma cell line and treated with anti-PD1 antibodies for 15 days. Response to therapy was monitored by assessment of tumor size. Cardiotoxicity was confirmed by mouse echocardiography. Mice were then simultaneously treated with anti-PD1 antibodies and TNFα-blocking antibodies. A cardioprotective effect was evaluated by echocardiography and flow cytometry was used to characterize myocardial immune cells.

Results

Mice receiving anti-PD1 showed smaller tumor sizes with increased immune cell infiltration compared to control littermates as a sign for a profound response to therapy. Cardiotoxicity was confirmed as demonstrated by reduced left ventricular ejection fraction and reduced global radial strain in anti-PD1-treated mice. Mice receiving anti-PD1 ICI therapy showed 2-fold elevated concentrations of CD4+ and CD8+ T-lymphocytes in the murine heart as determined by flow cytometry. CD44 expression was upregulated in cytotoxic T-cells as a marker of enhanced T-cell activity in anti-PD1 treated mice. Administration of TNFα-blocking antibodies did not alter tumor sizes during anti-PD1 treatment as a sign for a sustained response to therapy. Remarkably, mice receiving TNFα-blocking antibodies together with anti-PD1 ICI therapy showed increased left ventricular function compared to mice receiving anti-PD1 monotherapy. Flow cytometry revealed increased expression of T cell exhaustion markers in mice receiving TNFα blockade as a potential underlying mechanism.

Conclusions

ICI therapy targeting PD1 induces latent cardiotoxicity with left ventricular dysfunction. TNFα blockade may serve as a novel cardioprotective treatment without compromising the anti-tumor efficacy of ICI therapy. Prospective studies are needed to further characterize ICI-related cardiotoxicity in patients and to evaluate the cardioprotective effect of TNFα blockade.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): IFORES research grant, Medical Faculty, University Duisburg-Essen, Essen, Germany

Preclinical and clinical assessment of immune checkpoint inhibitor-associated left ventricular dysfunction

Background

Immune checkpoint inhibitor (ICI) therapy has improved treatment of advanced cancers but is associated with yet incompletely characterized cardiotoxic side effects. While inflammatory cardiac complications were initially described as a rare phenomenon, emerging evidence indicates frequent cardiotoxicity, particularly latent left ventricular (LV) dysfunction. Distinct clinical characteristics and potential pathomechanisms are so far unknown.

Purpose

This study aims to investigate incidence and frequency of LV dysfunction in patients receiving ICI therapy for malignant melanoma. Using a suitable melanoma mouse model, ICI-related cardiotoxicity will be reenacted to identify potential underlying pathomechanisms.

Methods

Patients receiving ICI therapy for stage IV melanoma that presented in our cardio-oncology unit were evaluated at baseline and four weeks after initiation of therapy including echocardiography, cardiac biomarkers, and dobutamine stress echocardiography in the absence of contraindications. Patients with decreased LV ejection fraction (LVEF) were further evaluated by 18-fludeoxyglucose PET-MRI to assess manifest myocarditis. To elucidate underlying pathomechanisms, we established a melanoma mouse model that showed profound response to anti-programmed death 1 (PD1) ICI therapy. Immune cell infiltration was assessed by flow cytometry and light sheet fluorescence microscopy. Myocardial biochemical function was analyzed using a multi-omics mass spectrometry-based approach.

Results

Seven patients were included to the analysis. Six patients received a combination ICI therapy with ipilimumab and nivolumab, and one patient received nivolumab monotherapy. Echocardiography revealed significantly decreased 3D-LVEF after 4 weeks of therapy in treated patients (p=0.021). A reduced global longitudinal strain was found in six of seven patients. Remarkably, dobutamine stress echocardiography revealed a more pronounced LVEF-decrease (p=0.009) as a sign for impaired myocardial contractility with a mean decrease of 5 percentage points. Using the melanoma mouse model, we were able to recapitulate the disease phenotype as indicated by decreased LVEF and impaired response to inotropic stress during mouse pressure/volume catheterization. Increased concentrations of intramyocardial CD4+ and CD8+ T cells were found in mice treated with anti-PD1 ICI therapy compared to controls (p=0.01). Mass spectrometry revealed disrupted energy metabolism and calcium homeostasis as a putative underlying pathomechanism for impaired myocardial function.

Conclusions

ICI-related left ventricular dysfunction may affect a large proportion of patients and potentially increase cardiac morbidity and mortality. Preclinical data proposes myocardial lymphocyte infiltration and disruption of cardiomyocyte metabolism as the underlying pathomechanism. Prospective studies are now needed for a further characterization of this novel form of ICI-related cardiotoxicity.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): IFORES research grant, Medical Faculty, University Duisburg-Essen, Germany

Macrophages/Microglia Represent the Major Source of Indolamine 2,3-Dioxygenase Expression in Melanoma Metastases of the Brain

The manifestation of brain metastases in patients with advanced melanoma is a common event that limits patient's survival and quality of life. The immunosuppressive properties of the brain parenchyma are very different compared to the rest of the body, making it plausible that the current success of cancer immunotherapies is specifically limited here. In melanoma brain metastases, the reciprocal interplay between immunosuppressive mediators such as indoleamine 2, 3-dioxygenase (IDO) or programmed cell death-ligand 1 (PD-L1) in the context of neoplastic transformation are far from being understood. Therefore, we analyzed the immunoreactive infiltrate (CD45, CD3, CD8, Forkhead box P3 [FoxP3], CD11c, CD23, CD123, CD68, Allograft Inflammatory factor 1[AIF-1]) and PD-L1 with respect to IDO expression and localization in melanoma brain metastases but also in matched metastases at extracranial sites to correlate intra- and interpatient data with therapy response and survival. Comparative tissue analysis identified macrophages/microglia as the major source of IDO expression in melanoma brain metastases. In contrast to the tumor infiltrating lymphocytes, melanoma cells per se exhibited low IDO expression levels paralleled by cell surface presentation of PD-L1 in intracranial metastases. Absolute numbers and pattern of IDO-expressing cells in metastases of the brain correlated with recruitment and localization of CD8⁺ T cells, implicating dynamic impact on the regulation of T cell function in the brain parenchyma. However, paired analysis of matched intra- and extracranial metastases identified significantly lower fractions of cytotoxic CD8⁺ T cells in intracranial metastases while all other immune cell populations remain unchanged. In line with the already established clinical benefit for PD-L1 expression in extracranial melanoma metastases, Kaplan-Meier analyses correlated PD-L1 expression in brain metastases with favorable outcome in advanced melanoma patients undergoing immune checkpoint therapy. In summary, our data provide new insights into the landscape of immunosuppressive factors in melanoma brain metastases that may be useful in the implication of novel therapeutic strategies for patients undergoing cancer immunotherapy.

2416PD1-blocking immune checkpoint inhibitor therapy for malignant melanoma induces left ventricular dysfunction

Background

Immune checkpoint inhibitor therapy has significantly improved treatment of advanced malignant diseases. However, patients receiving immune checkpoint inhibitor therapy with programmed death 1 (PD1) blocking agents are at risk for cardiotoxicity with high mortality. The underlying pathomechanisms have not yet been elucidated.

Purpose

This study aims to evaluate the cardiotoxic effect of PD1-blocking agents and its underlying mechanism with focus on myocardial inflammation and metabolism.

Methods

A transplantable melanoma mouse model was used to study PD1 blocking therapy in a preclinical setting. In brief, mice were subcutaneously transplanted with a melanoma cell line and treated with anti-PD1 antibodies or non-specific immunoglobulin control for 14 days. Murine transthoracic echocardiography including strain analysis was conducted to assess left ventricular (LV) function. Pressure/volume analysis was performed using a micro-tip catheter introduced into the LV via the right commune carotid artery. Inotropic stress was induced by dobutamine. Myocardial immune cell infiltration and expression of PD1/PD-L1 was assessed using flow cytometry. A combined approach for mass spectrometry-guided profiling of proteome, lipids and metabolites was applied to evaluate changes in cardiomyocyte function and metabolism.

Results

Reduced tumor size in anti-PD1-treated animals confirmed response to treatment (n=7; p=0.018). Echocardiographic examination revealed reduced LV ejection fraction (EF) (n=7–8; p=0.001) and reduced global radial strain in anti-PD1-treated mice compared to control littermates (n=3–4; p=0.004). Remarkably, pressure/volume catheterization indicated reduced EF, stroke volume and stroke work under dobutamine stress in anti-PD1-treated mice (p=0.013; n=3–4). Anti-PD1 treatment was associated with a 2-fold elevated level of CD4+ and CD8+ T-cells in murine hearts (n=8; p=0.009 and p=0.049). CD44 expression was upregulated in CD8+ T-cells of anti-PD1-treated animals (n=8; p=0.024). Proteomics revealed downregulation of proteins critical for cardiomyocyte contraction, e.g. ryanodine receptor 2 and L-type calcium channel beta 2 (n=4; p<0.05). Analysis of metabolites and lipids indicated dysfunctional energy metabolism. To identify a potential underlying mechanism, expression of PD1 and its ligand PD-L1 on cardiac cell populations was examined. PD-L1 was mainly expressed on cardiac endothelial cells while PD1 was expressed on 10–20% of murine cardiomyocytes (n=12; p<0.001 and p=0.004).

Conclusion

The obtained results point towards a cardiotoxic effect of PD1 blocking therapy with severely disturbed cardiac function and disrupted cardiomyocyte functional integrity. Myocardial expression of the PD1 receptor could mediate the observed effect. This could potentially promote the development of PD1 immune checkpoint inhibitor-associated myocarditis in patients.

Acknowledgement/Funding

IFORES research grant of the Medical Faculty, University Duisburg-Essen, Essen, Germany

Targeting the "undruggable" RAS - new strategies - new hope?

K-RAS is the most frequently mutated oncogene in solid tumors, such as pancreatic, colon or lung cancer. The GTPase K-RAS can either be in an active (GTP-loaded) or inactive (GDP-loaded) form. In its active form K-RAS forwards signals from growth factors, cytokines or hormones to the nucleus, regulating essential pathways, such as cell proliferation and differentiation. In turn, activating somatic mutations of this proto-oncogene deregulate the complex interplay between GAP (GTPase-activating) - and GEF (Guanine nucleotide exchange factor) - proteins, driving neoplastic transformation. Due to a rather shallow surface, K-RAS lacks proper binding pockets for small molecules, hindering drug development over the past thirty years. This review summarizes recent progress in the development of low molecular antagonists and further shows insights of a newly described interaction between mutant K-RAS signaling and PD-L1 induced immunosuppression, giving new hope for future treatments of K-RAS mutated cancer.

Allosteric Activation of GDP-Bound Ras Isoforms by Bisphenol Derivative Plasticisers

The protein family of small GTPases controls cellular processes by acting as a binary switch between an active and an inactive state. The most prominent family members are H-Ras, N-Ras, and K-Ras isoforms, which are highly related and frequently mutated in cancer. Bisphenols are widespread in modern life because of their industrial application as plasticisers. Bisphenol A (BPA) is the best-known member and has gained significant scientific as well as public attention as an endocrine disrupting chemical, a fact that eventually led to its replacement. However, compounds used to replace BPA still contain the molecular scaffold of bisphenols. BPA, BPAF, BPB, BPE, BPF, and an amine-substituted BPAF-derivate all interact with all GDP-bound Ras-Isoforms through binding to a common site on these proteins. NMR-, SOS^cat-, and GDI- assay-based data revealed a new bisphenol-induced, allosterically activated GDP-bound Ras conformation that define these plasticisers as Ras allosteric agonists.

Tension in Cancer

Integrins represent a large family of cell receptors that mediate adhesion to the extracellular matrix (ECM), thereby modulating a variety of cellular functions that are required for proliferation, migration, malignant conversion and invasiveness. During tumorigenesis the conversion of a tumor cell from sessile, stationary phenotype to an invasive phenotype requires the ability of tumor cells to interact with their environment in order to transduce signals from the ECM into the cells. Hence, there is increasing evidence that changes in the composition, topography and tension of tumor matrix can be sensed by integrin receptors, leading to the regulation of intracellular signalling events which subsequently help to fuel cancer progression. The fact that intracellular signals perceived from integrin ligand binding impact on almost all steps of tumor progression, including tumor cell proliferation, survival, metastatic dissemination and colonization of a metastatic niche, renders integrins as ideal candidates for the development of therapeutic agents. In this review we summarize the role of integrins in cancer with the special focus on cancer therapies and the recent progress that has been made in the understanding of “integrin-induced tension in cancer”. Finally, we conclude with clinical evidence for the role of integrin-mediated mechanotransduction in the development of therapy-resistant tumors.

Abstract A11: Targeting vascular endothelial growth factor in myeloid cells enhances natural killer cell responses to chemotherapy and ameliorates cachexia

Chemotherapy remains a mainstay of cancer treatment but its use is often limited by the development of adverse reactions. Severe involuntary loss of body weight (cachexia) is a frequent cause of death in cancer patients and is exacerbated by chemotherapy. We show that, in contrast to antibody-mediated neutralization of Vascular Endothelial Growth Factor (VEGF)-A, genetic inactivation of VEGF-A in tumor-associated myeloid cells prevents chemotherapy-induced cachexia by inhibiting skeletal muscle loss and the lipolysis of white adipose tissue. It also improves clearance of senescent tumor cells by natural killer cells and inhibits tumor regrowth after chemotherapy. The effects depend on the adipokine and chemoattractant chemerin, which is released by the tumur endothelium in response to chemotherapy. The findings define chemerin as a critical mediator of the immune response elicited by chemotherapy as well as an important inhibitor of cancer cachexia. Efficient targeting of VEGF signaling within the tumor microenvironment should impede weight loss that is frequently associated with chemotherapy, thereby dramatically improving the therapeutic outcome.

Citation Format: Magali Castells, Ralph Klose, Dagmar Gotthardt, Eva-Maria Putz, Ewelina Krzywinska, Chahrazade Kantari-Mimoun, Naima Chikdene, Anna-Katharina Meinecke, Katrin Schroedter, Iris Helfrich, Joachim Fandrey, Veronika Sexl, Christian Stockmann. Targeting vascular endothelial growth factor in myeloid cells enhances natural killer cell responses to chemotherapy and ameliorates cachexia. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr A11.

Regulation of hematogenous tumor metastasis by acid sphingomyelinase

Metastatic dissemination of cancer cells is the ultimate hallmark of malignancy and accounts for approximately 90% of human cancer deaths. We investigated the role of acid sphingomyelinase (Asm) in the hematogenous metastasis of melanoma cells. Intravenous injection of B16F10 melanoma cells into wild-type mice resulted in multiple lung metastases, while Asm-deficient mice (Smpd1^−/− mice) were protected from pulmonary tumor spread. Transplanting wild-type platelets into Asm-deficient mice reinstated tumor metastasis. Likewise, Asm-deficient mice were protected from hematogenous MT/ret melanoma metastasis to the spleen in a mouse model of spontaneous tumor metastasis. Human and mouse melanoma cells triggered activation and release of platelet secretory Asm, in turn leading to ceramide formation, clustering, and activation of α5β1 integrins on melanoma cells finally leading to adhesion of the tumor cells. Clustering of integrins by applying purified Asm or C₁₆ ceramide to B16F10 melanoma cells before intravenous injection restored trapping of tumor cells in the lung in Asm-deficient mice. This effect was revertable by arginine-glycine-aspartic acid peptides, which are known inhibitors of integrins, and by antibodies neutralizing β1 integrins. These findings indicate that melanoma cells employ platelet-derived Asm for adhesion and metastasis.

Role of Acid Sphingomyelinase-Induced Signaling in Melanoma Cells for Hematogenous Tumor Metastasis

BACKGROUND

Hematogenous metastasis of malignant tumor cells is a multistep process that requires release of tumor cells from the local tumor mass, interaction of the tumor cells with platelets in the blood, and adhesion of either the activated tumor cells or the complexes of platelets and tumor cells to the endothelial cells of the target organ. We have previously shown that the interaction of melanoma cells with platelets results in the release of acid sphingomyelinase (Asm) from activated platelets. Secreted platelet-derived Asm acts on malignant tumor cells to cluster and activate integrins; such clustering and activation are necessary for tumor cell adhesion to endothelial cells and for metastasis.

METHODS

We examined the response of tumor cells to treatment with extracellular sphingomyelinase or co-incubation with wild-type and Asm-deficient platelets. We determined the phosphorylation and activation of several intracellular signaling molecules, in particular p38 kinase (p38K), phospholipase Cx03B3; (PLCx03B3;), ezrin, and extracellular signal-regulated kinases.

RESULTS

Incubation of B16F10 melanoma cells with Asm activates p38 MAP kinase (p38K), phospholipase Cx03B3; (PLCx03B3;), ezrin, and extracellular signal-regulated kinases. Co-incubation of B16F10 melanoma cells with wild-type or Asm-deficient platelets showed that the phosphorylation/activation of p38K is dependent on Asm. Pharmacological blockade of p38K prevents activation of β1 integrin and adhesion in vitro. Most importantly, inhibition of p38K activity in B16F10 melanoma cells prevents tumor cell adhesion and metastasis to the lung in vivo, a finding indicating the importance of p38K for metastasis.

CONCLUSIONS

Asm, secreted from activated platelets after tumor cell-platelet contact, induces p38K phosphorylation in tumor cells. This in turn stimulates β1 integrin activation that is necessary for adhesion and subsequent metastasis of tumor cells. Thus, inhibition of p38K might be a novel target to prevent tumor metastasis.

MITF is a critical regulator of the carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) in malignant melanoma

The multifunctional Ig-like carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is neo-expressed in the majority of malignant melanoma lesions. CEACAM1 acts as a driver of tumor cell invasion, and its expression correlates with poor patient prognosis. Despite its importance in melanoma progression, how CEACAM1 expression is regulated is largely unknown. Here, we show that CEACAM1 expression in melanoma cell lines and melanoma tissue strongly correlates with that of the microphthalmia-associated transcription factor (MITF), a key regulator of melanoma proliferation and invasiveness. MITF is revealed as a direct and positive regulator for CEACAM1 expression via binding to an M-box motif located in the CEACAM1 promoter. Taken together, our study provides novel insights into the regulation of CEACAM1 expression and suggests an MITF-CEACAM1 axis as a potential determinant of melanoma progression.

CEACAM1-4L Promotes Anchorage-Independent Growth in Melanoma

Widespread metastasis is the leading course of death in many types of cancer, including malignant melanoma. The process of metastasis can be divided into a number of complex cell biological events, collectively termed the “invasion-metastasis cascade.” Previous reports have characterized the capability of anchorage-independent growth of cancer cells in vitro as a key characteristic of highly aggressive tumor cells, particularly with respect to metastatic potential. Biological heterogeneity as well as drastic alterations in cell adhesion of disseminated cancer cells support escape mechanisms for metastases to overcome conventional therapies. Here, we show that exclusively the carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) splice variant CEACAM1-4L supports an anchorage-independent signature in malignant melanoma. These results highlight important variant-specific modulatory functions of CEACAM1 for metastatic spread in patients suffering malignant melanoma.

Abstract 5254: Sentinel lymph node detection and in vivo/ex vivo assessment of melanin distribution by means of multispectral optoacoustic tomography (MSOT) in patients with malignant melanoma

Melanoma accounts for less than 5% of skin cancer cases, yet it causes more than 75% of skin cancer death, and its incidence is growing faster than any other cancer in the world. Because melanoma metastasizes early into regional/sentinel lymph nodes (SLN), SLN excision (SLNE) is probably the most important diagnostic procedure for melanoma patients, as histology provides the most relevant prognostic factor for the survival of melanoma patients. However, 50% of excised lymph nodes show no evidence of metastasis; and, current histological protocols involve sampling only a small portion of the SLN, resulting in a relatively high false negative rate. Furthermore, SLNE exposes the patients to complications such as swelling, edema and future risk of infection. Therefore, a clear need exists to improve the sensitivity and specificity of SLN analysis. Multispectral optoacoustic tomography (MSOT) ulitizes the molecular specificity of optical imaging, while capitalizing on the high temporal and spatial resolution of ultrasound imaging. This method allows sensitive detection of optical markers such as melanin, which would identify potentially metastatic lymph nodes, and indocyanine green (ICG), which can potentially label SLN. In this study, 148 lymph nodes were excised from 65 melanoma patients (stage I - IV), and the lymph nodes were examined by MSOT ex vivo to guide the pathologist to examination of melanin-containing regions of the lymph node, thereby increasing the detection rate in histological analysis. Compared to standard histology, MSOT demonstrated a superior 100% sensitivity/47% specificity. Further, 21 melanoma patients were scanned with a handheld MSOT device in vivo. MSOT was able to detect sentinel lymph nodes using ICG specific contrast, with the added ability of non-invasive assessment of the melanin status prior to excision. In vivo MSOT measurements using a 2D and a 3D detector were compared with ultrasound, SPECT/CT, planar fluorescence imaging and ex vivo histology, with a promising concordance between in vivo MSOT measurements and in vivo and ex vivo gold standard assessments. MSOT represents a viability modality to improve histological analysis of excised SLN in melanoma patients, and it offers the ability to stage lymph nodes noninvasively, potentially reducing the necessity to excise lymph nodes in some melanoma patients.

Citation Format: Stefan Morscher, Ingo Stoffels, Neal C. Burton, Jing Claussen, Thomas Sardella, Iris Helfrich, Uwe Hillen, Julia Leyh, Dirk Schadendorf, Matthias Gunzer, Joachim Klode. Sentinel lymph node detection and in vivo/ex vivo assessment of melanin distribution by means of multispectral optoacoustic tomography (MSOT) in patients with malignant melanoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5254. doi:10.1158/1538-7445.AM2015-5254

CEACAM1-3S Drives Melanoma Cells into NK Cell-Mediated Cytolysis and Enhances Patient Survival

CEACAM1 is a widely expressed multifunctional cell-cell adhesion protein reported to serve as a poor prognosis marker in melanoma patients. In this study, we examine the functional and clinical contributions of the four splice isoforms of CEACAM1. Specifically, we present in vitro and in vivo evidence that they affect melanoma progression and immune surveillance in a negative or positive manner that is isoform specific in action. In contrast with isoforms CEACAM1-4S and CEACAM1-4L, expression of isoforms CEACAM1-3S and CEACAM1-3L is induced during disease progression shown to correlate with clinical stage. Unexpectedly, overall survival was prolonged in patients with advanced melanomas expressing CEACAM1-3S. The favorable effects of CEACAM1-3S related to enhanced immunogenicity, which was mediated by cell surface upregulation of NKG2D receptor ligands, thereby sensitizing melanoma cells to lysis by natural killer cells. Conversely, CEACAM1-4L downregulated cell surface levels of the NKG2D ligands MICA and ULBP2 by enhanced shedding, thereby promoting malignant character. Overall, our results define the splice isoform-specific immunomodulatory and cell biologic functions of CEACAM1 in melanoma pathogenesis.

The impact of the immune system on tumor: angiogenesis and vascular remodeling

Angiogenesis, the formation of new blood vessels, as well as inflammation with massive infiltration of leukocytes are hallmarks of various tumor entities. Various epidemiological, clinical, and experimental studies have not only demonstrated a link between chronic inflammation and cancer onset but also shown that immune cells from the bone marrow such as tumor-infiltrating macrophages significantly influence tumor progression. Tumor angiogenesis is critical for tumor development as tumors have to establish a blood supply in order to progress. Although tumor cells were first believed to fuel tumor angiogenesis, numerous studies have shown that the tumor microenvironment and infiltrating immune cell subsets are important for regulating the process of tumor angiogenesis. These infiltrates involve the adaptive immune system including several types of lymphocytes as well as cells of the innate immunity such as macrophages, neutrophils, eosinophils, mast cells, dendritic cells, and natural killer cells. Besides their known immune function, these cells are now recognized for their crucial role in regulating the formation and the remodeling of blood vessels in the tumor. In this review, we will discuss for each cell type the mechanisms that regulate the vascular phenotype and its impact on tumor growth and metastasis.

Hyperlipidemia Attenuates Vascular Endothelial Growth Factor–Induced Angiogenesis, Impairs Cerebral Blood Flow, and Disturbs Stroke Recovery via Decreased Pericyte Coverage of Brain Endothelial Cells

Objective—

Therapeutic angiogenesis aims at the promotion of vascular growth, usually under conditions of atherosclerosis. It was unknown how hyperlipidemia, a risk factor that is closely associated with atherosclerosis of brain vessels in humans, influences vascular endothelial growth factor–induced angiogenesis and stroke recovery.

Approach and Results—

Wild-type and apolipoprotein-E (ApoE) −/− mice were kept on regular or cholesterol-rich diet for mimicking different severities of hyperlipidemia. Mice were treated intracerebroventricularly with recombinant human vascular endothelial growth factor for 21 days (0.02 µg/d) and subsequently subjected to 90-minute middle cerebral artery occlusion followed by 1 or 24 hours of reperfusion. Histochemical, autoradiographic, and regional bioluminescence techniques were used to evaluate effects of blood lipids on postischemic angiogenesis, histopathologic brain injury, cerebral blood flow, protein synthesis and energy state, and pericyte coverage of brain endothelial cells. Hyperlipidemia dose-dependently attenuated vascular endothelial growth factor–induced capillary formation and pericyte coverage of brain endothelial cells, abolishing the improvement of cerebral blood flow during subsequent stroke, resulting in the loss of the metabolic penumbra and increased brain infarction. The enhanced angiogenesis after vascular endothelial growth factor treatment was accompanied by increased expression of the adhesion protein N-cadherin, which mediates endothelial-pericytic interactions, in ischemic brain microvessels of wild-type mice on regular diet that was blunted in wild-type mice on Western diet and ApoE −/− mice on either diet.

Conclusions—

The compromised vessel formation and hemodynamics question the concept of therapeutic angiogenesis in ischemic stroke where hyperlipidemia is highly prevalent.

Neuropilin-1 mediates infiltration of regulatory T cells into tumors favoring immune escape (P2063)

Infiltration of tumors by Foxp3+ regulatory T cells contributes to tumor development and progression by dampening an effective anti-tumor immune response. We show that the surface receptor Neuropilin-1, highly expressed by Foxp3+ regulatory T cells, controls the immunological anti-tumor response by directing regulatory T cells into the tumor in a Vascular Endothelial Growth Factor dependent mode of action. Deletion of Neuropilin-1 in CD4+ T cells or abrogation of Vascular Endothelial Growth Factor production by the tumor cells itself resulted in a major impairment of tumor development and progression accompanied by an increased CD8+ T cell response. Most importantly, the frequency of tumor-infiltrating Foxp3+ regulatory T cells was clearly reduced within tumors from both T cell-specific Neuropilin-1-deficient mice and wild type mice transplanted with Vascular Endothelial Growth Factor-deficient tumor cells. From this, we conclude that Neuropilin-1 represents a key mediator of Foxp3+ regulatory T cell infiltration into Vascular Endothelial Growth Factor producing tumor sites.

Vascular endothelial growth factor promotes pericyte coverage of brain capillaries, improves cerebral blood flow during subsequent focal cerebral ischemia, and preserves the metabolic penumbra

BACKGROUND AND PURPOSE

Therapeutic angiogenesis aims at improving cerebral blood flow by amplification of vascular sprouting, thus promoting tissue survival under conditions of subsequent ischemia. It remains unknown whether induced angiogenesis leads to the formation of functional vessels that indeed result in hemodynamic improvements. Observations of hemodynamic steal phenomena and disturbed neurovascular integrity after vascular endothelial growth factor delivery questioned the concept of therapeutic angiogenesis.

METHODS

Mice were treated with recombinant human vascular endothelial growth factor (0.02 μg/d; intracerebroventricular) for 3 to 21 days and subsequently exposed to 90-minute middle cerebral artery occlusion. Angiogenesis, histological brain injury, IgG extravasation, cerebral blood flow, protein synthesis and energy state, and pericyte coverage on brain capillaries were evaluated in a multiparametric approach combining histochemical, autoradiographic, and regional bioluminescence techniques.

RESULTS

Vascular endothelial growth factor increased brain capillary density within 10 days and reduced infarct volume and inflammation after subsequent middle cerebral artery occlusion, and, when delivered for prolonged periods of 21 days, enhanced postischemic blood-brain barrier integrity. Increased cerebral blood flow was noted in ischemic brain areas exhibiting enhanced angiogenesis and was associated with preservation of the metabolic penumbra, defined as brain tissue in which protein synthesis has been suppressed but ATP preserved. Vascular endothelial growth factor enhanced pericyte coverage of brain endothelial cells via mechanisms involving increased N-cadherin expression on cerebral microvessels.

CONCLUSIONS

That cerebral blood flow is increased during subsequent ischemic episodes, leading to the stabilization of cerebral energy state, fosters hope that by promoting new vessel formation brain tissue survival may be improved.

Neuropilin 1 deficiency on CD4+Foxp3+ regulatory T cells impairs mouse melanoma growth

Neuropilin 1 mediates anti-tumor control by promoting regulatory T cell infiltration.

Infiltration of Foxp3⁺ regulatory T (T reg) cells is considered to be a critical step during tumor development and progression. T reg cells supposedly suppress locally an effective anti-tumor immune response within tumor tissues, although the precise mechanism by which T reg cells infiltrate the tumor is still unclear. We provide evidence that Neuropilin 1 (Nrp-1), highly expressed by Foxp3⁺ T reg cells, regulates the immunological anti-tumor control by guiding T reg cells into the tumor in response to tumor-derived vascular endothelial growth factor (VEGF). We demonstrate for the first time that T cell–specific ablation of Nrp-1 expression results in a significant breakdown in tumor immune escape in various transplantation models and in a spontaneous, endogenously driven melanoma model associated with strongly reduced tumor growth and prolonged tumor-free survival. Strikingly, numbers of tumor-infiltrating Foxp3⁺ T reg cells were significantly reduced accompanied by enhanced activation of CD8⁺ T cells within tumors of T cell–specific Nrp-1–deficient mice. This phenotype can be reversed by adoptive transfer of Nrp-1⁺ T reg cells from wild-type mice. Thus, our data strongly suggest that Nrp-1 acts as a key mediator of Foxp3⁺ T reg cell infiltration into the tumor site resulting in a dampened anti-tumor immune response and enhanced tumor progression.

Blood vessel maturation, vascular phenotype and angiogenic potential in malignant melanoma: one step forward for overcoming anti-angiogenic drug resistance?

Angiogenesis is a pivotal process for growth, invasion and spread of the majority of solid tumors including melanoma. Anti-angiogenic agents have not been systematically tested in patients with advanced melanoma. Clinical efficacy of angiogenesis inhibitors targeting endothelial cells has not been as affirmative as initially hoped and improved clinical outcomes have been observed in combination with chemotherapy or additional drugs for many types of human cancer. However, angiogenesis is not only dependent on endothelial cell invasion and proliferation, it also requires pericyte coverage of vascular sprouts for stabilization and maturation of vascular walls. Recent data suggest that pericytes might be able to confer resistance to anti-vascular endothelial growth factor (VEGF) therapy. This review will focus on the significance of the vascular phenotype but also on the impact of pericyte-mediated vessel maturation for the susceptibility to anti-angiogenic therapy, including malignant melanoma, which we identified as crucial factor regarding therapeutic efficacy.

Drug treatment of chronic-intermittent abdominal cramping and pain: a multi-national survey on usage and attitudes

BACKGROUND

Data on drug treatment of abdominal cramping and pain are sparse.

AIM

To compare treatment of abdominal cramping and pain across countries worldwide.

METHODS

A multi-national survey was conducted in the USA, Mexico, Brazil, Argentina, Germany, Belgium, Italy and the UK. In each country, approximately 210 people were interviewed on various aspects of drug treatment of their complaints.

RESULTS

In total, 1717 participants were interviewed. Respondents from the Americas used more medication (approximately 90%) than those from Europe (approximately 70%). Over-the-counter remedies were much more used than prescription drugs (except for Mexico). Medication was mainly taken on demand to relieve a pain episode. In the Latin American countries, antispasmodics were most popular (up to 73%), in Germany antacids, and in the UK antacids and analgesics. Regarding expectations of treatment, 'fast onset of action' ranked the highest, followed by 'highly effective' and 'well tolerated'.

CONCLUSIONS

A majority of people afflicted by abdominal cramping and pain use medication and take them on demand. Consequently, rapid onset of action is mentioned as most important. Antispasmodics are the class most frequently used with considerable variation from country to country.

Resistance to antiangiogenic therapy is directed by vascular phenotype, vessel stabilization, and maturation in malignant melanoma

Angiogenesis is not only dependent on endothelial cell invasion and proliferation, it also requires pericyte coverage of vascular sprouts for stabilization of vascular walls. Clinical efficacy of angiogenesis inhibitors targeting the vascular endothelial growth factor (VEGF) signaling pathway is still limited to date. We hypothesized that the level of vessel maturation is critically involved in the response to antiangiogenic therapies. To test this hypothesis, we evaluated the vascular network in spontaneously developing melanomas of MT/ret transgenic mice after using PTK787/ZK222584 for anti-VEGF therapy but also analyzed human melanoma metastases taken at clinical relapse in patients undergoing adjuvant treatment using bevacizumab. Both experimental settings showed that tumor vessels, which are resistant to anti-VEGF therapy, are characterized by enhanced vessel diameter and normalization of the vascular bed by coverage of mature pericytes and immunoreactivity for desmin, NG-2, platelet-derived growth factor receptor β, and the late-stage maturity marker α smooth muscle actin. Our findings emphasize that the level of mural cell differentiation and stabilization of the vascular wall significantly contribute to the response toward antiangiogenic therapy in melanoma. This study may be useful in paving the way toward a more rational development of second generation antiangiogenic combination therapies and in providing, for the first time, a murine model to study this.

Angiopoietin-2 levels are associated with disease progression in metastatic malignant melanoma

PURPOSE

The blood vessel-destabilizing Tie2 ligand angiopoietin-2 (Ang-2) acts in concert with the vascular endothelial growth factor/vascular endothelial growth factor receptor system to control vessel assembly during tumor progression. We hypothesized that circulating soluble Ang-2 (sAng-2) may be involved in melanoma progression.

EXPERIMENTAL DESIGN

Serum samples (n=98) from melanoma patients (American Joint Committee on Cancer stages I-IV), biopsies of corresponding patients, and human melanoma cell lines were analyzed for expression of Ang-2 and S100beta. Multiple sera of a subcohort of 33 patients were tested during progression from stage III to IV. Small interfering RNA-based loss-of-function experiments were done to assess effects of Ang-2 on melanoma cells.

RESULTS

Circulating levels of sAng-2 correlate with tumor progression in melanoma patients (P<0.0001) and patient survival (P=0.007). Analysis of serum samples during the transition from stage III to IV identified an increase of sAng-2 up to 400%. Comparative analyses revealed a 56% superiority of sAng-2 as predictive marker over the established marker S100beta. Immunohistochemistry and reverse transcription-PCR confirmed the prominent expression of Ang-2 by tumor-associated endothelial cells but identified Ang-2 also as a secreted product of melanoma cells themselves. Corresponding cellular experiments revealed that human melanoma-isolated tumor cells were Tie2 positive and that Ang-2 acted as an autocrine regulator of melanoma cell migration and invasion.

CONCLUSIONS

The experiments establish sAng-2 as a biomarker of melanoma progression and metastasis correlating with tumor load and overall survival. The identification of an autocrine angiopoietin/Tie loop controlling melanoma migration and invasion warrants further functional experiments and validate the angiopoietin/Tie system as a promising therapeutic target for human melanomas.

Host-derived angiopoietin-2 affects early stages of tumor development and vessel maturation but is dispensable for later stages of tumor growth

The angiopoietin/Tie2 system has been identified as the second vascular-specific receptor tyrosine kinase system controlling vessel assembly, maturation, and quiescence. Angiopoietin-2 (Ang-2) is prominently up-regulated in the host-derived vasculature of most tumors, making it an attractive candidate for antiangiogenic intervention. Yet, the net outcome of Ang-2 functions on tumor angiogenesis is believed to be contextual depending on the local cytokine milieu. Correspondingly, Ang-2 manipulatory therapies have been shown to exert protumorigenic as well as antitumorigenic effects. To clarify the role of Ang-2 for angiogenesis and tumor growth in a definite genetic experimental setting, the present study was aimed at comparatively studying the growth of different tumors in wild-type and Ang-2-deficient mice. Lewis lung carcinomas, MT-ret melanomas, and B16F10 melanomas all grew slower in Ang-2-deficient mice. Yet, tumor growth in wild-type and Ang-2-deficient mice dissociated during early stages of tumor development, whereas tumor growth rates during later stages of primary tumor progression were similar. Analysis of the intratumoral vascular architecture revealed no major differences in microvessel density and perfusion characteristics. However, diameters of intratumoral microvessels were smaller in tumors grown in Ang-2-deficient mice, and the vasculature had an altered pattern of pericyte recruitment and maturation. Ang-2-deficient tumor vessels had higher pericyte coverage indices. Recruited pericytes were desmin and NG2 positive and predominately alpha-smooth muscle actin negative, indicative of a more mature pericyte phenotype. Collectively, the experiments define the role of Ang-2 during tumor angiogenesis and establish a better rationale for combination therapies involving Ang-2 manipulatory therapies.

A multinational survey of prevalence and patterns of laxative use among adults with self-defined constipation

BACKGROUND

While numerous studies report prevalence of constipation, use of laxatives is poorly understood.

AIM

To conduct a survey in seven countries evaluating prevalence of constipation and laxative use in its treatment.

METHODS

Thirteen thousand eight hundred seventy-nine adults [approximately 2000 each from US, UK, Germany (GE), France (FR), Italy (IT), Brazil (BR) and South Korea (SK)] completed questionnaires assessing occurrence, frequency, duration and laxative use for treating constipation.

RESULTS

Overall, 12.3% of adults had constipation [range: 5% (GE) to 18% (US)] in the prior year. A greater percent of women from all countries and elderly from all except SK and BR reported constipation; odds ratios for constipation among women and elderly were 2.43 (95% CI: 2.18-2.71) and 1.5 (95% CI: 1.25-1.73) vs. men and young subjects. Among those with constipation, 16% (SK) to 40% (US) used laxatives. Laxative use was generally associated with increasing age, symptom frequency and lower income and education. A similar percentage of men and women with constipation reported using laxatives; a greater percentage of women used laxatives for a longer time.

CONCLUSIONS

Prevalence of self-defined constipation and laxative use varies among countries. Prevalence is generally related to gender and age, whereas laxative use is related to age, but not to gender.

Endosialin (Tem1) is a marker of tumor-associated myofibroblasts and tumor vessel-associated mural cells

Endosialin (Tem1) has been identified by two independent experimental approaches as an antigen of tumor-associated endothelial cells, and it has been claimed to be the most abundantly expressed tumor endothelial antigen, making it a prime candidate for vascular targeting purposes. Recent experiments have challenged the endothelial expression of endosialin and suggested an expression by activated fibroblasts and pericytes. Thus, clarification of the controversial cellular expression of endosialin is critically important for an understanding of its role during tumor progression and its validation as a potential therapeutic target. We have therefore performed extensive expression profiling analyses of endosialin. The experiments unambiguously demonstrate that endosialin is expressed by tumor-associated myofibroblasts and mural cells and not by endothelial cells. Endosialin expression is barely detectable in normal human tissues with moderate expression only detectable in the stroma of the colon and the prostate. Corresponding cellular experiments confirmed endosialin expression by mesenchymal cells and indicated that it may in fact be a marker of mesenchymal stem cells. Silencing endosialin expression in fibroblasts strongly inhibited migration and proliferation. Collectively, the experiments validate endosialin as a marker of tumor-associated myofibroblasts and tumor vessel-associated mural cells. The data warrant further functional analysis of endosialin during tumor progression and its exploitation as marker of tumor vessel-associated mural cells, expression of which may reflect the non-normalized phenotype of the tumor vasculature.

The burden of constipation on quality of life: results of a multinational survey

BACKGROUND

The impact of constipation on quality of life (QoL) may vary in different cultural or national settings.

AIM

We studied QoL in a multinational survey to compare different social and demographic groups with and without constipation (defined according to Rome III criteria) and to detect country-specific differences among the groups studied.

METHODS

Health-related QoL (HRQoL) was assessed with the Short Form 36 (SF-36) questionnaire in 2870 subjects in France, Germany, Italy, UK, South Korea, Brazil and USA. Results Respondents were mainly middle-aged, married or living together and part- or full-time employed. General health status, measured by the SF-36 questionnaire, was significantly worse in the constipated vs. non-constipated populations.

RESULTS

were comparable in all countries. QoL scores correlated negatively with age. Constipated women reported more impaired HRQoL than constipated men. Brazilians were most affected by constipation as to their social functioning (35.8 constipated vs. 51.3 non-constipated) and general health perception (29.4 constipated vs. 54.4 non-constipated).

CONCLUSIONS

There are significant differences in HRQoL between constipated and non-constipated individuals and a significant, negative correlation between the number of symptoms and complaints and SF-36 scores. The study detected a correlation of constipation with QoL and the influence of social and demographic factors on HRQoL in constipated people.

Role of aPKC isoforms and their binding partners Par3 and Par6 in epidermal barrier formation

The skin water barrier, essential for terrestrial life, is formed by a multilayered stratifying epithelium, which shows a polarized distribution of both differentiation and intercellular junction markers. Recently, several reports showed the crucial importance of tight junctions for the in vivo water barrier function of the skin. In simple epithelial cells, intercellular junction formation is closely coupled to the establishment of polarity. However, if and how polarity proteins contribute to epidermal differentiation and junction formation is not yet known. Here, we have characterized the localization and isoform expression of the polarity protein atypical PKC (aPKC) and its binding partners Par3 and Par6 in epidermis and primary keratinocytes of mice. Their distribution is only partially overlapping in the granular layer, the site of functional tight junctions, suggesting that next to a common Par3/Par6/aPKC function they also may have functions independent of each other. Both aPKCzeta and aPKCiota/lambda, are expressed in the epidermis but only aPKCiota/lambda showed a strong enrichment in the junctions, suggesting that this aPKC isoform is important for epidermal tight junction function. Indeed, inhibition of aPKC function showed that endogenous aPKC is crucial for in vitro barrier function and this required the presence of both the Par3 and Par6 binding sites.

Prevalence and management of abdominal cramping and pain: a multinational survey

BACKGROUND

Though functional gastrointestinal complaints are recognised as being common throughout the world, there have been few comparative studies of prevalence.

AIM

To compare the prevalence and management of abdominal cramping/pain in nine countries.

METHODS

In a two-stage community survey, approximately 1000 subjects were interviewed in each of nine countries to establish the demographics of individuals with abdominal cramping/pain (stage 1) followed by market research-driven interviews with >or=200 sufferers per country (stage 2).

RESULTS

9042 subjects were interviewed in stage 1. Mexico (46%) and Brazil (43%) had the highest prevalence of abdominal cramping/pain; Japan the lowest (10%). Abdominal cramping/pain was more common in women (12-55%) than in men (7-38%). About 1717 subjects participated in stage 2; 65% were women and the average age at symptom onset was 29 years. The frequency of episodes differed between countries, being highest in the US (61% suffered at least once in a week). Sufferers in the US and Latin America reported a higher usage of medications (around 90%) than those in Europe (around 72%). In most countries over-the-counter drugs were principally used. Antispasmodic drugs were most popular in Latin America and Italy, antacids in Germany and the UK. Drug therapy decreased the duration of episodes (by up to 81% in Brazil).

CONCLUSIONS

The community prevalence, severity, healthcare seeking and medication usage related to abdominal cramping/pain are high overall, but vary considerably between countries.

E-cadherin is essential for in vivo epidermal barrier function by regulating tight junctions

Cadherin adhesion molecules are key determinants of morphogenesis and tissue architecture. Nevertheless, the molecular mechanisms responsible for the morphogenetic contributions of cadherins remain poorly understood in vivo. Besides supporting cell-cell adhesion, cadherins can affect a wide range of cellular functions that include activation of cell signalling pathways, regulation of the cytoskeleton and control of cell polarity. To determine the role of E-cadherin in stratified epithelium of the epidermis, we have conditionally inactivated its gene in mice. Here we show that loss of E-cadherin in the epidermis in vivo results in perinatal death of mice due to the inability to retain a functional epidermal water barrier. Absence of E-cadherin leads to improper localization of key tight junctional proteins, resulting in permeable tight junctions and thus altered epidermal resistance. In addition, both Rac and activated atypical PKC, crucial for tight junction formation, are mislocalized. Surprisingly, our results indicate that E-cadherin is specifically required for tight junction, but not desmosome, formation and this appears to involve signalling rather than cell contact formation.

Increased incidence of squamous cell carcinomas in Mastomys natalensis papillomavirus E6 transgenic mice during two-stage skin carcinogenesis

Papillomaviruses cause certain forms of human cancers, most notably carcinomas of the uterine cervix. In contrast to the well-established involvement of papillomavirus infection in the etiology of cervical carcinomas and in carcinomas of a rare hereditary condition, epidermodysplasia verruciformis, a causative role for cutaneous human papillomavirus types in the development of nonmelanoma skin cancer has not been proven. In order to better understand the functions of individual genes of cutaneous papillomavirus types, we generated transgenic mice carrying oncogene E6 of the Mastomys natalensis papillomavirus (MnPV), which causes keratoacanthomas of the skin in its natural host. In the present study, we demonstrate that under conditions of experimental two-stage skin carcinogenesis, fast-paced squamous cell carcinomas develop in nearly 100% of MnPV E6 transgenic mice in comparison to 10% in their nontransgenic littermates (log rank test; P < 0.0001). Therefore, we conclude that the MnPV E6 transgene favors the malignant progression of chemically induced tumors. Whereas an activating H-ras mutation is a consistent feature in benign and malignant tumors in wild-type mice, the majority of papillomas and keratoacanthomas and all squamous cell carcinomas obtained in MnPV E6 transgenic mice contain nonmutated ras alleles. These results indicate that the development of squamous cell carcinomas in MnPV E6 transgenic mice does not depend on an activated H-ras oncogene.