Tumour-associated macrophages and melanoma tumourigenesis: integrating the complexity

Angiogenesis Still Plays a Crucial Role in Human Melanoma Progression

Angiogenesis plays a pivotal role in tumor progression, particularly in melanoma, the deadliest form of skin cancer. This review synthesizes current knowledge on the intricate interplay between angiogenesis and tumor microenvironment (TME) in melanoma progression. Pro-angiogenic factors, including VEGF, PlGF, FGF-2, IL-8, Ang, TGF-β, PDGF, integrins, MMPs, and PAF, modulate angiogenesis and contribute to melanoma metastasis. Additionally, cells within the TME, such as cancer-associated fibroblasts, mast cells, and melanoma-associated macrophages, influence tumor angiogenesis and progression. Anti-angiogenic therapies, while showing promise, face challenges such as drug resistance and tumor-induced activation of alternative angiogenic pathways. Rational combinations of anti-angiogenic agents and immunotherapies are being explored to overcome resistance. Biomarker identification for treatment response remains crucial for personalized therapies. This review highlights the complexity of angiogenesis in melanoma and underscores the need for innovative therapeutic approaches tailored to the dynamic TME.

Deciphering ligand-receptor-mediated intercellular communication based on ensemble deep learning and the joint scoring strategy from single-cell transcriptomic data

BACKGROUND

Cell-cell communication in a tumor microenvironment is vital to tumorigenesis, tumor progression and therapy. Intercellular communication inference helps understand molecular mechanisms of tumor growth, progression and metastasis.

METHODS

Focusing on ligand-receptor co-expressions, in this study, we developed an ensemble deep learning framework, CellComNet, to decipher ligand-receptor-mediated cell-cell communication from single-cell transcriptomic data. First, credible LRIs are captured by integrating data arrangement, feature extraction, dimension reduction, and LRI classification based on an ensemble of heterogeneous Newton boosting machine and deep neural network. Next, known and identified LRIs are screened based on single-cell RNA sequencing (scRNA-seq) data in certain tissues. Finally, cell-cell communication is inferred by incorporating scRNA-seq data, the screened LRIs, a joint scoring strategy that combines expression thresholding and expression product of ligands and receptors.

RESULTS

The proposed CellComNet framework was compared with four competing protein-protein interaction prediction models (PIPR, XGBoost, DNNXGB, and OR-RCNN) and obtained the best AUCs and AUPRs on four LRI datasets, elucidating the optimal LRI classification ability. CellComNet was further applied to analyze intercellular communication in human melanoma and head and neck squamous cell carcinoma (HNSCC) tissues. The results demonstrate that cancer-associated fibroblasts highly communicate with melanoma cells and endothelial cells strong communicate with HNSCC cells.

CONCLUSIONS

The proposed CellComNet framework efficiently identified credible LRIs and significantly improved cell-cell communication inference performance. We anticipate that CellComNet can contribute to anticancer drug design and tumor-targeted therapy.

Exploring association of melanoma-specific Bcl-xL with tumor immune microenvironment

BACKGROUND

Macrophages take center stage in the tumor microenvironment, a niche composed of extracellular matrix and a heterogeneous group of cells, including immune ones. They can evolve during tumor progression and acquire Tumor-Associated Macrophage (TAMs) phenotype. The release of cytokines by tumor and stromal cells, influence the secretion of cytokines by TAMs, which can guarantee tumor progression and influence the response to therapy. Among all factors able to recruit and polarize macrophages, we focused our attention on Bcl-xL, a multifaceted member of the Bcl-2 family, whose expression is deregulated in melanoma. It acts not only as a canonical pro-survival and anti-apoptotic protein, but also as a promoter of tumor progression.

METHODS

Human melanoma cells silencing or overexpressing Bcl-xL protein, THP-1 monocytic cells and monocyte-derived macrophages were used in this study. Protein array and specific neutralizing antibodies were used to analyze cytokines and chemokines secreted by melanoma cells. qRT-PCR, ELISA and Western Blot analyses were used to evaluate macrophage polarization markers and protein expression levels. Transwell chambers were used to evaluate migration of THP-1 and monocyte-derived macrophages. Mouse and zebrafish models were used to evaluate the ability of melanoma cells to recruit and polarize macrophages in vivo.

RESULTS

We demonstrated that melanoma cells overexpressing Bcl-xL recruit macrophages at the tumor site and induce a M2 phenotype. In addition, we identified that interleukin-8 and interleukin-1β cytokines are involved in macrophage polarization, and the chemokine CCL5/RANTES in the macrophages recruitment at the tumor site. We also found that all these Bcl-xL-induced factors are regulated in a NF-kB dependent manner in human and zebrafish melanoma models.

CONCLUSIONS

Our findings confirmed the pro-tumoral function of Bcl-xL in melanoma through its effects on macrophage phenotype.

The role of tumor-associated macrophages and soluble mediators in pulmonary metastatic melanoma

Skin malignant melanoma is a highly aggressive skin tumor, which is also a major cause of skin cancer-related mortality. It can spread from a relatively small primary tumor and metastasize to multiple locations, including lymph nodes, lungs, liver, bone, and brain. What’s more metastatic melanoma is the main cause of its high mortality. Among all organs, the lung is one of the most common distant metastatic sites of melanoma, and the mortality rate of melanoma lung metastasis is also very high. Elucidating the mechanisms involved in the pulmonary metastasis of cutaneous melanoma will not only help to provide possible explanations for its etiology and progression but may also help to provide potential new therapeutic targets for its treatment. Increasing evidence suggests that tumor-associated macrophages (TAMs) play an important regulatory role in the migration and metastasis of various malignant tumors. Tumor-targeted therapy, targeting tumor-associated macrophages is thus attracting attention, particularly for advanced tumors and metastatic tumors. However, the relevant role of tumor-associated macrophages in cutaneous melanoma lung metastasis is still unclear. This review will present an overview of the origin, classification, polarization, recruitment, regulation and targeting treatment of tumor-associated macrophages, as well as the soluble mediators involved in these processes and a summary of their possible role in lung metastasis from cutaneous malignant melanoma. This review particularly aims to provide insight into mechanisms and potential therapeutic targets to readers, interested in pulmonary metastasis melanoma.

Tumor-Associated Macrophages in Canine Oral and Cutaneous Melanomas and Melanocytomas: Phenotypic and Prognostic Assessment

The tumor microenvironment is a complex system, where neoplastic cells interact with immune and stromal cells. Tumor-associated macrophages (TAMs) are considered among the most numerically and biologically noteworthy cellular components in tumors and the attention on this cellular population has been growing during the last decade, both for its prognostic role and as a potential future therapeutic target. Melanoma, particularly the oral form, despite being one of the most immunogenic tumors, bears a poor prognosis in dogs and humans, due to its highly aggressive biological behavior and limited therapeutic options. The aims of this study are to characterize and quantify TAMs (using CD163, CD204, Iba1, and MAC387) in canine melanocytic tumors and to evaluate the association of these markers with diagnosis, histologic prognostic features, presence of metastases, and outcome, and to provide preliminary data for possible future therapies targeting TAMs. Seventy-two melanocytic tumors (27 oral melanomas, 25 cutaneous melanomas, 14 cutaneous melanocytomas, and 6 oral melanocytomas) were retrospectively selected and submitted to immunohistochemistry and double immunofluorescence. Double immunolabeling revealed that most CD163⁺ and CD204⁺cells co-expressed Iba1, which labeled also dendritic cells. Iba1 was instead rarely co-expressed with MAC387. Nevertheless, the expression of macrophagic markers showed a mild to moderate association among the four markers, except for CD204 and MAC387. The number of CD163⁺, CD204⁺, and MAC387⁺ cells was significantly higher in oral melanomas compared to oral melanocytomas (p < 0.001; p < 0.05 and p < 0.01, respectively), whereas Iba1 was differentially expressed in cutaneous melanomas and melanocytomas (p < 0.05). Moreover, CD163, IBA1 and MAC387 expression was associated with nuclear atypia and mitotic count. The number of CD163⁺cells was associated with the presence of metastases and tumor-related death in oral melanocytic tumors (p < 0.05 and p = 0.001, respectively).

Near-Infrared Bioluminescence Imaging of Macrophage Sensors for Cancer Detection In Vivo

Melanoma is an aggressive type of skin cancer with a poor prognosis after it gets metastasized. The early detection of malignant melanoma is critical for effective therapy. Because melanoma often resembles moles, routine skin check-up may help for timely identification of suspicious areas. Recently, it has been shown that the interplay of melanoma cells with the immune system can help develop efficient therapeutic strategies. Here, we leveraged engineered macrophages (BMC2) as cell-based sensors for metastatic melanoma. To perform dual-color bioluminescence imaging (BLI) in vivo, macrophages were engineered to express a green click beetle luciferase (CBG2) and a near-infrared fluorescent dye (DiR), and B16F10 melanoma cells were instead engineered to express a near-infrared click beetle luciferase (CBR2). Using real-time in vivo dual-color BLI and near-infrared fluorescence (FL) imaging, we could demonstrate that macrophages were able to sense and substantially accumulate in subcutaneous and metastatic melanoma tissues at 72 h after systemic injections. Together, we showed the potentiality to use optical imaging technologies to track circulating macrophages for the non-invasive detection of metastatic melanoma.

Inhibition of renalase drives tumour rejection by promoting T cell activation

BACKGROUND

Although programmed cell death protein 1 (PD-1) inhibitors have revolutionised treatment for advanced melanoma, not all patients respond. We previously showed that inhibition of the flavoprotein renalase (RNLS) in preclinical melanoma models decreases tumour growth. We hypothesised that RNLS inhibition promotes tumour rejection by effects on the tumour microenvironment (TME).

METHODS

We used two distinct murine melanoma models, studied in RNLS knockout (KO) or wild-type (WT) mice. WT mice were treated with the anti-RNLS antibody, m28, with or without anti-PD-1. 10X single-cell RNA-sequencing was used to identify transcriptional differences between treatment groups, and tumour cell content was interrogated by flow cytometry. Samples from patients treated with immunotherapy were examined for RNLS expression by quantitative immunofluorescence.

RESULTS

RNLS KO mice injected with wild-type melanoma cells reject their tumours, supporting the importance of RNLS in cells in the TME. This effect was blunted by anti-cluster of differentiation 3. However, MØ-specific RNLS ablation was insufficient to abrogate tumour formation. Anti-RNLS antibody treatment of melanoma-bearing mice resulted in enhanced T cell infiltration and activation and resulted in immune memory on rechallenging mice with injection of melanoma cells. At the single-cell level, treatment with anti-RNLS antibodies resulted in increased tumour density of MØ, neutrophils and lymphocytes and increased expression of IFNγ and granzyme B in natural killer cells and T cells. Intratumoural Forkhead Box P3 + CD4 cells were decreased. In two distinct murine melanoma models, we showed that melanoma-bearing mice treated with anti-RNLS antibodies plus anti-PD-1 had superior tumour shrinkage and survival than with either treatment alone. Importantly, in pretreatment samples from patients treated with PD-1 inhibitors, high RNLS expression was associated with decreased survival (log-rank P = 0.006), independent of other prognostic variables.

CONCLUSIONS

RNLS KO results in melanoma tumour regression in a T-cell-dependent fashion. Anti-RNLS antibodies enhance anti-PD-1 activity in two distinct aggressive murine melanoma models resistant to PD-1 inhibitors, supporting the development of anti-RNLS antibodies with PD-1 inhibitors as a novel approach for melanomas poorly responsive to anti-PD-1.

Canine Melanoma Immunology and Immunotherapy: Relevance of Translational Research

In veterinary oncology, canine melanoma is still a fatal disease for which innovative and long-lasting curative treatments are urgently required. Considering the similarities between canine and human melanoma and the clinical revolution that immunotherapy has instigated in the treatment of human melanoma patients, special attention must be paid to advancements in tumor immunology research in the veterinary field. Herein, we aim to discuss the most relevant knowledge on the immune landscape of canine melanoma and the most promising immunotherapeutic approaches under investigation. Particular attention will be dedicated to anti-cancer vaccination, and, especially, to the encouraging clinical results that we have obtained with DNA vaccines directed against chondroitin sulfate proteoglycan 4 (CSPG4), which is an appealing tumor-associated antigen with a key oncogenic role in both canine and human melanoma. In parallel with advances in therapeutic options, progress in the identification of easily accessible biomarkers to improve the diagnosis and the prognosis of melanoma should be sought, with circulating small extracellular vesicles emerging as strategically relevant players. Translational advances in melanoma management, whether achieved in the human or veterinary fields, may drive improvements with mutual clinical benefits for both human and canine patients; this is where the strength of comparative oncology lies.

Macrophage-Mediated Melanoma Reduction after HP-NAP Treatment in a Zebrafish Xenograft Model

The Helicobacter pylori Neutrophil Activating Protein (HP-NAP) is endowed with immunomodulatory properties that make it a potential candidate for anticancer therapeutic applications. By activating cytotoxic Th1 responses, HP-NAP inhibits the growth of bladder cancer and enhances the anti-tumor activity of oncolytic viruses in the treatment of metastatic breast cancer and neuroendocrine tumors. The possibility that HP-NAP exerts its anti-tumor effect also by modulating the activity of innate immune cells has not yet been explored. Taking advantage of the zebrafish model, we examined the therapeutic efficacy of HP-NAP against metastatic human melanoma, limiting the observational window to 9 days post-fertilization, well before the maturation of the adaptive immunity. Human melanoma cells were xenotransplanted into zebrafish embryos and tracked in the presence or absence of HP-NAP. The behavior and phenotype of macrophages and the impact of their drug-induced depletion were analyzed exploiting macrophage-expressed transgenes. HP-NAP administration efficiently inhibited tumor growth and metastasis and this was accompanied by strong recruitment of macrophages with a pro-inflammatory profile at the tumor site. The depletion of macrophages almost completely abrogated the ability of HP-NAP to counteract tumor growth. Our findings highlight the pivotal role of activated macrophages in counteracting melanoma growth and support the notion that HP-NAP might become a new biological therapeutic agent for the treatment of metastatic melanomas.

Interleukin-8 in Melanoma Pathogenesis, Prognosis and Therapy-An Integrated View into Other Neoplasms and Chemokine Networks

Cutaneous melanoma accounts for only about 7% of skin cancers but is causing almost 90% of deaths. Melanoma cells have a distinct repertoire of mutations from other cancers, a high plasticity and degree of mimicry toward vascular phenotype, stemness markers, versatility in evading and suppress host immune control. They exert a significant influence on immune, endothelial and various stromal cells which form tumor microenvironment. The metastatic stage, the leading cause of mortality in this neoplasm, is the outcome of a complex, still poorly understood, cross-talk between tumor and other cell phenotypes. There is accumulating evidence that Interleukin-8 (IL-8) is emblematic for advanced melanomas. This work aimed to present an updated status of IL-8 in melanoma tumor cellular complexity, through a comprehensive analysis including data from other chemokines and neoplasms. The multiple processes and mechanisms surveyed here demonstrate that IL-8 operates following orchestrated programs within signaling webs in melanoma, stromal and vascular cells. Importantly, the yet unknown molecularity regulating IL-8 impact on cells of the immune system could be exploited to overturn tumor fate. The molecular and cellular targets of IL-8 should be brought into the attention of even more intense scientific exploration and valorization in the therapeutical management of melanoma.

A Phase I Study of APX005M and Cabiralizumab with or without Nivolumab in Patients with Melanoma, Kidney Cancer, or Non-Small Cell Lung Cancer Resistant to Anti-PD-1/PD-L1

PURPOSE

PD-1/PD-L1 inhibitors are approved for multiple tumor types. However, resistance poses substantial clinical challenges.

PATIENTS AND METHODS

We conducted a phase I trial of CD40 agonist APX005M (sotigalimab) and CSF1R inhibitor cabiralizumab with or without nivolumab using a 3+3 dose-escalation design (NCT03502330). Patients were enrolled from June 2018 to April 2019. Eligibility included patients with biopsy-proven advanced melanoma, non-small cell lung cancer (NSCLC), or renal cell carcinoma (RCC) who progressed on anti-PD-1/PD-L1. APX005M was dose escalated (0.03, 0.1, or 0.3 mg/kg i.v.) with a fixed dose of cabiralizumab with or without nivolumab every 2 weeks until disease progression or intolerable toxicity.

RESULTS

Twenty-six patients (12 melanoma, 1 NSCLC, and 13 RCC) were enrolled in six cohorts, 17 on nivolumab-containing regimens. Median duration of follow-up was 21.3 months. The most common treatment-related adverse events were asymptomatic elevations of lactate dehydrogenase (n = 26), creatine kinase (n = 25), aspartate aminotransferase (n = 25), and alanine aminotransferase (n = 19); periorbital edema (n = 17); and fatigue (n = 13). One dose-limiting toxicity (acute respiratory distress syndrome) occurred in cohort 2. The recommended phase 2 dose was APX005M 0.3 mg/kg, cabiralizumab 4 mg/kg, and nivolumab 240 mg every 2 weeks. Median days on treatment were 66 (range, 23-443). Median cycles were 4.5 (range, 2-21). One patient had unconfirmed partial response (4%), 8 stable disease (31%), 16 disease progression (62%), and 1 unevaluable (4%). Pro-inflammatory cytokines were upregulated 4 hours post-infusion. CD40 and MCSF increased after therapy.

CONCLUSIONS

This first in-human study of patients with anti-PD-1/PD-L1-resistant tumors treated with dual macrophage-polarizing therapy, with or without nivolumab demonstrated safety and pharmacodynamic activity. Optimization of the dosing frequency and sequence of this combination is warranted.

Proof-of-Concept Study of Multifunctional Hybrid Nanoparticle System Combined with NIR Laser Irradiation for the Treatment of Melanoma

The global impact of cancer emphasizes the importance of developing innovative, effective and minimally invasive therapies. In the context of superficial cancers, the development of a multifunctional nanoparticle-based system and its in vitro and in vivo safety and efficacy characterization are, herein, proposed as a proof-of-concept. This multifunctional system consists of gold nanoparticles coated with hyaluronic and oleic acids, and functionalized with epidermal growth factor for greater specificity towards cutaneous melanoma cells. This nanoparticle system is activated by a near-infrared laser. The characterization of this nanoparticle system included several phases, with in vitro assays being firstly performed to assess the safety of gold nanoparticles without laser irradiation. Then, hairless immunocompromised mice were selected for a xenograft model upon inoculation of A375 human melanoma cells. Treatment with near-infrared laser irradiation for five minutes combined with in situ administration of the nanoparticles showed a tumor volume reduction of approximately 80% and, in some cases, led to the formation of several necrotic foci, observed histologically. No significant skin erythema at the irradiation zone was verified, nor other harmful effects on the excised organs. In conclusion, these assays suggest that this system is safe and shows promising results for the treatment of superficial melanoma.

Melanoma-specific bcl-2 promotes a protumoral M2-like phenotype by tumor-associated macrophages

Background

A bidirectional crosstalk between tumor cells and the surrounding microenvironment contributes to tumor progression and response to therapy. Our previous studies have demonstrated that bcl-2 affects melanoma progression and regulates the tumor microenvironment. The aim of this study was to evaluate whether bcl-2 expression in melanoma cells could influence tumor-promoting functions of tumor-associated macrophages, a major constituent of the tumor microenvironment that affects anticancer immunity favoring tumor progression.

Methods

THP-1 monocytic cells, monocyte-derived macrophages and melanoma cells expressing different levels of bcl-2 protein were used. ELISA, qRT-PCR and Western blot analyses were used to evaluate macrophage polarization markers and protein expression levels. Chromatin immunoprecipitation assay was performed to evaluate transcription factor recruitment at specific promoters. Boyden chamber was used for migration experiments. Cytofluorimetric and immunohistochemical analyses were carried out to evaluate infiltrating macrophages and T cells in melanoma specimens from patients or mice.

Results

Higher production of tumor-promoting and chemotactic factors, and M2-polarized activation was observed when macrophages were exposed to culture media from melanoma cells overexpressing bcl-2, while bcl-2 silencing in melanoma cells inhibited the M2 macrophage polarization. In agreement, the number of melanoma-infiltrating macrophages in vivo was increased, in parallel with a greater expression of bcl-2 in tumor cells. Tumor-derived interleukin-1β has been identified as the effector cytokine of bcl-2-dependent macrophage reprogramming, according to reduced tumor growth, decreased number of M2-polarized tumor-associated macrophages and increased number of infiltrating CD4⁺IFNγ⁺ and CD8⁺IFNγ⁺ effector T lymphocytes, which we observed in response to in vivo treatment with the IL-1 receptor antagonist kineret. Finally, in tumor specimens from patients with melanoma, high bcl-2 expression correlated with increased infiltration of M2-polarized CD163⁺ macrophages, hence supporting the clinical relevance of the crosstalk between tumor cells and microenvironment.

Conclusions

Taken together, our results show that melanoma-specific bcl-2 controls an IL-1β-driven axis of macrophage diversion that establishes tumor microenvironmental conditions favoring melanoma development. Interfering with this pathway might provide novel therapeutic strategies.

PD-1 siRNA-Encapsulated Solid Lipid Nanoparticles Downregulate PD-1 Expression by Macrophages and Inhibit Tumor Growth : PD-1 siRNA-Encapsulated Solid Lipid Nanoparticles

The present study was designed to test the hypothesis that programmed cell death-1 (PD-1) siRNA can downregulate PD-1 expression in macrophages in culture and in tumor tissues in mice and inhibit tumor growth in a mouse model. PD-1 siRNA was encapsulated in solid lipid nanoparticles (SLNs), and the physical properties of the resultant SLNs were characterized. The ability of the PD-1 siRNA-SLNs to downregulate PD-1 expression was confirmed in J774A.1 macrophages in culture and in tumor tissues in mice. Moreover, the antitumor activity of the PD-1 siRNA-SLNs was evaluated in a mouse model. The PD-1 siRNA-SLNs were roughly spherical, and their particle size, polydispersity index, and zeta potential were 141 ± 5 nm, 0.17 ± 0.02, and 20.7 ± 4.7 mV, respectively, with an siRNA entrapment efficiency of 98.9%. The burst release of the PD-1 siRNA from the SLNs was minimal. The PD-1 siRNA-SLNs downregulated PD-1 expression on J774A.1 macrophage cell surface as well as in macrophages in B16-F10 tumors pre-established in mice. In mice with pre-established B16-F10 tumors, the PD-1 siRNA-SLNs significantly inhibited the tumor growth, as compared with siRNA-SLNs prepared with non-functional, negative control siRNA. In conclusion, the PD-1 siRNA-SLNs inhibited tumor growth, likely related to their ability to downregulate PD-1 expression by tumor-associated macrophage (TAMs).

CCL25 Signaling in the Tumor Microenvironment

Multiple checkpoint mechanisms are overridden by cancer cells in order to develop into a tumor. Neoplastic cells, while constantly changing during the course of cancer progression, also craft their surroundings to meet their growing needs. This crafting involves changing cell surface receptors, affecting response to extracellular signals and secretion of signals that affect the nearby cells and extracellular matrix architecture. This chapter briefly comprehends the non-cancer cells facilitating the cancer growth and elaborates on the notable role of the CCR9-CCL25 chemokine axis in shaping the tumor microenvironment (TME), directly and via immune cells. Association of increased CCR9 and CCL25 levels in various tumors has demonstrated the significance of this axis as a tool commonly used by cancer to flourish. It is involved in attracting immune cells in the tumor and determining their fate via various direct and indirect mechanisms and, leaning the TME toward immunosuppressive state. Besides, elevated CCR9-CCL25 signaling allows survival and rapid proliferation of cancer cells in an otherwise repressive environment. It modulates the intra- and extracellular protein matrix to instigate tumor dissemination and creates a supportive metastatic niche at the secondary sites. Lastly, this chapter abridges the latest research efforts and challenges in using the CCR9-CCL25 axis as a cancer-specific target.

Three-dimensional multicellular cell culture for anti-melanoma drug screening: focus on tumor microenvironment

Abstract

The development of new treatments for malignant melanoma, which has the worst prognosis among skin neoplasms, remains a challenge. The tumor microenvironment aids tumor cells to grow and resist to chemotherapeutic treatment. One way to mimic and study the tumor microenvironment is by using three-dimensional (3D) co-culture models (spheroids). In this study, a melanoma heterospheroid model composed of cancer cells, fibroblasts, and macrophages was produced by liquid-overlay technique using the agarose gel. The size, growth, viability, morphology, cancer stem-like cells population and inflammatory profile of tumor heterospheroids and monospheroids were analyzed to evaluate the influence of stromal cells on these parameters. Furthermore, dacarbazine cytotoxicity was evaluated using spheroids and two-dimensional (2D) melanoma model. After finishing the experiments, it was observed the M2 macrophages induced an anti-inflammatory microenvironment in heterospheroids; fibroblasts cells support the formation of the extracellular matrix, and a higher percentage of melanoma CD271 was observed in this model. Additionally, melanoma spheroids responded differently to the dacarbazine than the 2D melanoma culture as a result of their cellular heterogeneity and 3D structure. The 3D model was shown to be a fast and reliable tool for drug screening, which can mimic the in vivo tumor microenvironment regarding interactions and complexity.

Graphic abstract

Immunotherapy for Glioblastoma: Current State, Challenges, and Future Perspectives

Glioblastoma is the most lethal intracranial primary malignancy by no optimal treatment option. Cancer immunotherapy has achieved remarkable survival benefits against various advanced tumors, such as melanoma and non-small-cell lung cancer, thus triggering great interest as a new therapeutic strategy for glioblastoma. Moreover, the central nervous system has been rediscovered recently as a region for active immunosurveillance. There are vibrant investigations for successful glioblastoma immunotherapy despite the fact that initial clinical trial results are somewhat disappointing with unique challenges including T-cell dysfunction in the patients. This review will explore the potential of current immunotherapy modalities for glioblastoma treatment, especially focusing on major immune checkpoint inhibitors and the future strategies with novel targets and combo therapies. Immune-related adverse events and clinical challenges in glioblastoma immunotherapy are also summarized. Glioblastoma provides persistent difficulties for immunotherapy with a complex state of patients’ immune dysfunction and a variety of constraints in drug delivery to the central nervous system. However, rational design of combinational regimens and new focuses on myeloid cells and novel targets to circumvent current limitations hold promise to advent truly viable immunotherapy for glioblastoma.

Anticancer Activity of Liquid Treated with Microwave Plasma-Generated Gas through Macrophage Activation

Reactive nitrogen species (RNS), including nitric oxide (NO^·) has been known as one of the key regulatory molecules in the immune system. In this study, we generated RNS-containing water treated with microwave plasma-generated gas in which the major component was nitric oxide (PGNO), and the effect on the macrophage polarization was investigated. The RNS-containing water was diluted in complete cell culture media (PGNO-solution) into the concentration that did not induce cell death in RAW 264.7 murine macrophages. PGNO-solution upregulates M1-type macrophage activation and downregulates the characteristics of M2-type macrophage at the transcriptional level. In addition, the PGNO-solution-treated M2-like macrophages had higher potential in killing melanoma cells. The anticancer potential was also investigated in a syngeneic mouse model. Our results show that PGNO-solution has the potential to convert the fate of macrophages, suggesting PGNO-solution treatment as a supportive method for controlling the function of macrophages under the tumor microenvironment.

In vivo assessment of tumour associated macrophages in murine melanoma obtained by low-field relaxometry in the presence of iron oxide particles

Tumour-associated macrophages (TAM) are forced by cancer cells to adopt an anti-inflammatory phenotype and secrete factors to promote tumour invasion thus being responsible for poor patient outcome. The aim of this study is to develop a clinically applicable, non-invasive method to obtain a quantitative TAM detection in tumour tissue. The method is based on longitudinal proton relaxation rate (R₁) measurements at low field (0.01-1 MHz) to assess the localization of ferumoxytol (clinical approved iron oxide particles) in TAM present in melanoma tumours, where R₁ = 1/T₁. R₁ at low magnetic fields appears highly dependent on the intra or extra cellular localization of the nanoparticles thus allowing an unambiguous TAM quantification. R₁ profiles were acquired on a Fast Field-Cycling relaxometer equipped with a 40 mm wide bore magnet and an 11 mm solenoid detection coil placed around the anatomical region of interest. The R₁ values measured 3 h and 24 h after the injection were significantly different. At 24 h R₁ exhibited a behavior similar to "in vitro" ferumoxytol-labelled J774A.1 macrophages whereas at 3 h, when the ferumoxytol distribution was extracellular, R₁ exhibited higher values similar to that of free ferumoxytol in solution. This finding clearly indicated the intracellular localization of ferumoxytol at 24 h, as confirmed by histological analysis (Pearls and CD68 assays). This information could be hardly achievable from measurements at a single magnetic field and opens new horizons for cell tracking applications using FFC-MRI.

Investigating Macrophages Plasticity Following Tumour-Immune Interactions During Oncolytic Therapies

Over the last few years, oncolytic virus therapy has been recognised as a promising approach in cancer treatment, due to the potential of these viruses to induce systemic anti-tumour immunity and selectively killing tumour cells. However, the effectiveness of these viruses depends significantly on their interactions with the host immune responses, both innate (e.g., macrophages, which accumulate in high numbers inside solid tumours) and adaptive (e.g., \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {CD8}^{+}$$\end{document}CD8+ T cells). In this article, we consider a mathematical approach to investigate the possible outcomes of the complex interactions between two extreme types of macrophages (M1 and M2 cells), effector \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {CD8}^{+}$$\end{document}CD8+ T cells and an oncolytic Vesicular Stomatitis Virus (VSV), on the growth/elimination of B16F10 melanoma. We discuss, in terms of VSV, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {CD8}^{+}$$\end{document}CD8+ and macrophages levels, two different types of immune responses which could ensure tumour control and eventual elimination. We show that both innate and adaptive anti-tumour immune responses, as well as the oncolytic virus, could be very important in delaying tumour relapse and eventually eliminating the tumour. Overall this study supports the use mathematical modelling to increase our understanding of the complex immune interaction following oncolytic virotherapies. However, the complexity of the model combined with a lack of sufficient data for model parametrisation has an impact on the possibility of making quantitative predictions.

Racial Differences in Immunological Landscape Modifiers Contributing to Disparity in Prostate Cancer

Prostate cancer affects African Americans disproportionately by exhibiting greater incidence, rapid disease progression, and higher mortality when compared to their Caucasian counterparts. Additionally, standard treatment interventions do not achieve similar outcome in African Americans compared to Caucasian Americans, indicating differences in host factors contributing to racial disparity. African Americans have allelic variants and hyper-expression of genes that often lead to an immunosuppressive tumor microenvironment, possibly contributing to more aggressive tumors and poorer disease and therapeutic outcomes than Caucasians. In this review, we have discussed race-specific differences in external factors impacting internal milieu, which modify immunological topography as well as contribute to disparity in prostate cancer.

Kunitz type protease inhibitor from the canine tapeworm as a potential therapeutic for melanoma

Modulating the tumor microenvironment to promote an effective immune response is critical in managing any type of tumor. Melanoma is an aggressive skin cancer and the incidence rate is increasing worldwide. Potent protease inhibitors have recently been extensively researched as potential therapeutic agents against various cancers. EgKI-1 is a potent Kunitz type protease inhibitor identified from the canine tapeworm Echinococcus granulosus that has shown anti-cancer activities in vivo. In this study we show that EgKI-1 significantly reduced the growth of melanoma in the B16-F0 mouse model and was not toxic to normal surrounding tissue. Moreover, EgKI-1 treatment significantly reduced survivin expression levels and increased the CD8+ T cell population in draining axillary lymph nodes. Therefore, EgKI-1 potentially reduces tumor growth by inducing apoptosis and modulating the tumor microenvironment, and has potential for development as an intra-lesional treatment for melanoma.

A role of eosinophils in mediating the anti-tumour effect of cryo-thermal treatment

Previous, we established a novel therapeutic approach to tumour of cryo-thermal therapy, which can induce durable anti-tumour memory immunity mediated by CD4⁺ T cell, and contribute to prolonged survival in B16F10 murine melanoma model and 4T1 murine mammary carcinoma. It has become apparent that innate immune cells are involved in the regulation of adaptive T cell immunity. Our previous studies revealed that cryo-thermal therapy induced M1 macrophage polarization and DCs maturation were required for the shaping of systemic long-lived T cell mediated anti-tumour memory immunity. Eosinophils are multifunctional innate effector cells and there is lack of knowledge on the role of eosinophils in cryo-thermal-induced anti-tumour immunity. This study revealed that cryo-thermal therapy activated eosinophils in spleen at early stage following the treatment. Furthermore, cryo-thermal-activated eosinophils exerted versatile immunologic regulation from innate immunity to anti-tumour adaptive immunity, such as M1 macrophage polarization, DCs maturation, differentiation of CD4-CTL subtypes and enhanced cytotoxicity of CD8⁺ T cells. Our study indicated that the cryo-thermal-activated eosinophils was essential for the shaping of durable anti-tumour memory immunity. Thus, our results present a new concept for eosinophils mediated anti-tumour immunity after cryo-thermal therapy.

Antimetastatic and antiangiogenic activity of trabectedin in cutaneous melanoma

Trabectedin is a marine-derived antineoplastic drug. Besides targeting the cancer cells, trabectedin has a peculiar activity on the tumor microenvironment with marked effects on the vasculature and the immune response. Because a favorable microenvironment is a key factor in the progression of cutaneous melanoma, we hypothesized that trabectedin might affect the growth and metastasis of this highly aggressive cancer. This study shows that trabectedin inhibited the subcutaneous growth of the murine melanoma B16-BL6 and K1735-M2. In line with its known activities on the environment of other tumor types, it caused a significant reduction of tumor blood vessel density and tumor-associated macrophages. Trabectedin had a significant antimetastatic activity, inhibiting the formation of lung colonies following intravenous injection of B16-BL6 or K1735-M2 cells. The drug was also active in a clinically relevant spontaneous metastasis assay, where it inhibited lung metastasis when administered before (neoadjuvant) or after (adjuvant) surgical removal of the primary tumor. Relevant to its antimetastatic activity, trabectedin inhibited melanoma cell invasiveness in vitro, associated with increased tissue inhibitor of metalloproteinase-1 production and alteration in cell shape and cytoskeleton organization. This study shows that trabectedin affects melanoma growth and metastasis, acting with tumor-dependent mechanisms on both the tumor cells and the vascular and the inflammatory tumor microenvironment.

Regional Activation of Myosin II in Cancer Cells Drives Tumor Progression via a Secretory Cross-Talk with the Immune Microenvironment

ROCK-Myosin II drives fast rounded-amoeboid migration in cancer cells during metastatic dissemination. Analysis of human melanoma biopsies revealed that amoeboid melanoma cells with high Myosin II activity are predominant in the invasive fronts of primary tumors in proximity to CD206+CD163+ tumor-associated macrophages and vessels. Proteomic analysis shows that ROCK-Myosin II activity in amoeboid cancer cells controls an immunomodulatory secretome, enabling the recruitment of monocytes and their differentiation into tumor-promoting macrophages. Both amoeboid cancer cells and their associated macrophages support an abnormal vasculature, which ultimately facilitates tumor progression. Mechanistically, amoeboid cancer cells perpetuate their behavior via ROCK-Myosin II-driven IL-1α secretion and NF-κB activation. Using an array of tumor models, we show that high Myosin II activity in tumor cells reprograms the innate immune microenvironment to support tumor growth. We describe an unexpected role for Myosin II dynamics in cancer cells controlling myeloid function via secreted factors.

Upregulation of FOXP1 is a new independent unfavorable prognosticator and a specific predictor of lymphatic dissemination in cutaneous melanoma patients

Background

FOXP1 is a pleiotropic protein that plays important roles in immune responses (B-cell development regulation and differentiation of monocyte), organ development (cardiac valves, lung, and esophagus), and neuronal development. Besides being the primary regulator of normal human tissue development, FOXP1 also plays a role in tumorigenesis. However, the potential value of FOXP1 expression in tumor prognosis remains controversial. FOXP1 expression was assessed in tumor cells (TCs) and stromal cells (SCs) of cutaneous melanomas with the aim of analyzing the associations between FOXP1 expression and clinicopathological characteristics. We believe this article to be the first report analyzing the correlations between FOXP1 expression and clinicopathological, as well as histological, characteristics in melanoma.

Materials and methods

In total, 96 formalin-fixed, paraffin-embedded primary cutaneous melanoma tissue specimens were subjected to immunohistochemical analysis for FOXP1, and the results were correlated with classical clinicopathological features and patient survival.

Results

FOXP1 overexpression in TCs was strongly associated with the presence of metastases in sentinel lymph nodes (p=0.0003, OR=11.66) and positive status of regional lymph nodes (p=0.0006, OR=22.15). In 96% (52 of 54) of patients presenting with low FOXP1 expression, no clinical or histopathological features of lymphatic dissemination were observed. However, thinner and nonulcerated tumors were reported to have increased numbers of FOXP1-positive SCs. In addition, a strong association was observed between FOXP1 upregulation in SCs and the absence of regional lymph node metastases. There was a significant correlation between FOXP1 upregulation in TCs and shorter cancer-specific overall survival (log-rank test, p=0.0040) and disease-free survival (log-rank test, p=0.0021). FOXP1 expression was confirmed in multivariate analysis as a factor that significantly unfavorably impacts prognosis in melanoma patients (HR=3.14, p=0.0299, adjusted for age, Breslow thickness, and sex).

Conclusion

The findings from this study indicate that FOXP1 has a major role in melanoma progression, which makes it a candidate for molecular target-based cancer therapy.

Myeloid-targeted immunotherapies act in synergy to induce inflammation and antitumor immunity

Eliciting effective antitumor immune responses in patients who fail checkpoint inhibitor therapy is a critical challenge in cancer immunotherapy, and in such patients, tumor-associated myeloid cells and macrophages (TAMs) are promising therapeutic targets. We demonstrate in an autochthonous, poorly immunogenic mouse model of melanoma that combination therapy with an agonistic anti-CD40 mAb and CSF-1R inhibitor potently suppressed tumor growth. Microwell assays to measure multiplex protein secretion by single cells identified that untreated tumors have distinct TAM subpopulations secreting MMP9 or cosecreting CCL17/22, characteristic of an M2-like state. Combination therapy reduced the frequency of these subsets, while simultaneously inducing a separate polyfunctional inflammatory TAM subset cosecreting TNF-α, IL-6, and IL-12. Tumor suppression by this combined therapy was partially dependent on T cells, and on TNF-α and IFN-γ. Together, this study demonstrates the potential for targeting TAMs to convert a "cold" into an "inflamed" tumor microenvironment capable of eliciting protective T cell responses.

Combination therapy for melanoma with BRAF/MEK inhibitor and immune checkpoint inhibitor: a mathematical model

BACKGROUND

The B-raf gene is mutated in up to 66% of human malignant melanomas, and its protein product, BRAF kinase, is a key part of RAS-RAF-MEK-ERK (MAPK) pathway of cancer cell proliferation. BRAF-targeted therapy induces significant responses in the majority of patients, and the combination BRAF/MEK inhibitor enhances clinical efficacy, but the response to BRAF inhibitor and to BRAF/MEK inhibitor is short lived. On the other hand, treatment of melanoma with an immune checkpoint inhibitor, such as anti-PD-1, has lower response rate but the response is much more durable, lasting for years. For this reason, it was suggested that combination of BRAF/MEK and PD-1 inhibitors will significantly improve overall survival time.

RESULTS

This paper develops a mathematical model to address the question of the correlation between BRAF/MEK inhibitor and PD-1 inhibitor in melanoma therapy. The model includes dendritic and cancer cells, CD 4+ and CD 8+ T cells, MDSC cells, interleukins IL-12, IL-2, IL-6, IL-10 and TGF- β, PD-1 and PD-L1, and the two drugs: BRAF/MEK inhibitor (with concentration γ B ) and PD-1 inhibitor (with concentration γ A ). The model is represented by a system of partial differential equations, and is used to develop an efficacy map for the combined concentrations (γ B ,γ A ). It is shown that the two drugs are positively correlated if γ B and γ A are at low doses, that is, the growth of the tumor volume decreases if either γ B or γ A is increased. On the other hand, the two drugs are antagonistic at some high doses, that is, there are zones of (γ B ,γ A ) where an increase in one of the two drugs will increase the tumor volume growth, rather than decrease it.

CONCLUSIONS

It will be important to identify, by animal experiments or by early clinical trials, the zones of (γ B ,γ A ) where antagonism occurs, in order to avoid these zones in more advanced clinical trials.

Participation of Tumor-Associated Myeloid Cells in Progression of Amelanotic Melanoma (RMM Tumor Line) in F344 Rats, with Particular Reference to MHC Class II- and CD163-Expressing Cells

Tumor progression is often influenced by infiltration of myeloid cells; depending on the M1- or M2-like activation status, these cells may have either inhibitory or promoting effects on tumor growth. We investigated the properties of tumor-associated myeloid cells in a previously established homotransplantable amelanotic melanoma (RMM tumor line) in F344 rats. RMM tumor nodules were allowed to reach the sizes of 0.5, 1, 2 and 3 cm, respectively. Immunohistochemistry and flow cytometry was performed for macrophage markers CD68 and CD163, and for the antigen-presenting cell marker, MHC class II. Although no significant change was observed in the number of CD68⁺ and CD163⁺ macrophages during RMM progression, the number of MHC class II⁺ antigen-presenting cells was reduced in 3 cm nodules. Real-time RT-PCR of laser microdissection samples obtained from RMM regions rich in MHC class II⁺ cells demonstrated high expressions of M1-like factors: IFN-γ, GM-CSF and IL-12a. Furthermore, fluorescence-activated cell sorting, followed by real-time RT-PCR for CD11b⁺ MHC class II⁺ (myeloid antigen-presenting cells), CD11b⁺ CD163⁺ (M2 type myeloid cells), CD11b⁺ CD80⁺ (M1 type myeloid cells) and CD11b⁺ CD11c⁺ (dendritic cells) cells was performed. Based on the levels of inflammation- and tumor progression-related factors, MHC class II⁺ antigen-presenting cells showed polarization towards M1, while CD163⁺ macrophages, towards M2. CD80⁺ and CD11c⁺ myeloid cells did not show clear functional polarization. Our results provide novel information on tumor-associated myeloid cells in amelanotic melanoma, and may become useful in further research on melanoma immunity.

Primary Tr1 cells from metastatic melanoma eliminate tumor-promoting macrophages through granzyme B- and perforin-dependent mechanisms

In malignant melanoma, tumor-associated macrophages play multiple roles in promoting tumor growth, such as inducing the transformation of melanocytes under ultraviolet irradiation, increasing angiogenesis in melanomas, and suppressing antitumor immunity. Because granzyme B- and perforin-expressing Tr1 cells could specifically eliminate antigen-presenting cells of myeloid origin, we examined whether Tr1 cells in melanoma could eliminate tumor-promoting macrophages and how the interaction between Tr1 cells and macrophages could affect the growth of melanoma cells. Tr1 cells were characterized by high interleukin 10 secretion and low Foxp3 expression and were enriched in the CD4⁺CD49b⁺LAG-3⁺ T-cell fraction. Macrophages derived from peripheral blood monocytes in the presence of modified melanoma-conditioned media demonstrated tumor-promoting capacity, exemplified by improving the proliferation of cocultured A375 malignant melanoma cells. But when primary Tr1 cells were present in the macrophage-A375 coculture, the growth of A375 cells was abrogated. The conventional CD25⁺ Treg cells, however, were unable to inhibit macrophage-mediated increase in tumor cell growth. Further analyses showed that Tr1 cells did not directly eliminate A375 cells, but mediated the killing of tumor-promoting macrophages through the secretion of granzyme B and perforin. The tumor-infiltrating interleukin 10⁺Foxp3^-CD4⁺ T cells expressed very low levels of granzyme B and perforin, possibly suggested the downregulation of Tr1 cytotoxic capacity in melanoma tumors. Together, these data demonstrated an antitumor function of Tr1 cells through the elimination of tumor-promoting macrophages, which was not shared by conventional Tregs.

Downregulation of sphingosine kinase-1 induces protective tumor immunity by promoting M1 macrophage response in melanoma

The infiltration of melanoma tumors by macrophages is often correlated with poor prognosis. However, the molecular signals that regulate the dialogue between malignant cells and the inflammatory microenvironment remain poorly understood. We previously reported an increased expression of sphingosine kinase-1 (SK1), which produces the bioactive lipid sphingosine 1-phosphate (S1P), in melanoma. The present study aimed at defining the role of tumor SK1 in the recruitment and differentiation of macrophages in melanoma. Herein, we show that downregulation of SK1 in melanoma cells causes a reduction in the percentage of CD206highMHCIIlow M2 macrophages in favor of an increased proportion of CD206lowMHCIIhigh M1 macrophages into the tumor. This macrophage differentiation orchestrates T lymphocyte recruitment as well as tumor rejection through the expression of Th1 cytokines and chemokines. In vitro experiments indicated that macrophage migration is triggered by the binding of tumor S1P to S1PR1 receptors present on macrophages whereas macrophage differentiation is stimulated by SK1-induced secretion of TGF-β1. Finally, RNA-seq analysis of human melanoma tumors revealed a positive correlation between SK1 and TGF-β1 expression. Altogether, our findings demonstrate that melanoma SK1 plays a key role in the recruitment and phenotypic shift of the tumor macrophages that promote melanoma growth.

Golgi-Related Proteins GOLPH2 (GP73/GOLM1) and GOLPH3 (GOPP1/MIDAS) in Cutaneous Melanoma: Patterns of Expression and Prognostic Significance

GOLPH2 and GOLPH3 are Golgi-related proteins associated with aggressiveness and progression of a number of cancers. Their prognostic significance in melanoma has not yet been analyzed. We performed immunohistochemical analysis for GOLPH2 and GOLPH3 in 20 normal skin, 30 benign nevi and 100 primary melanoma tissue samples and evaluated their expression in three compartments: cancer cells, tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs). High levels of both proteins in melanoma cells were associated with characteristics of aggressive disease, and shorter disease-free survival (DFS) and cancer-specific overall survival (CSOS). On the contrary, increased numbers of GOLPH2-positive and GOLPH3-positive TAMs were observed in thinner, non-ulcerated tumors, with brisk lymphocytic reaction and absent lymphangioinvasion. Distant metastases were not observed among patients with high numbers of GOLPH2-positive TAMs. Increased expression of either protein in TAMs was related to prolonged CSOS and DFS. Similarly, GOLPH3-expressing CAFs were more frequent in thin melanomas with low mitotic rate, without ulceration and lymphangioinvasion. Moreover, increased GOLPH3-positive CAFs correlated with the absence of regional or distant metastases, and with longer CSOS and DFS. GOLPH2 expression was not observed in CAFs. Our results suggest that GOLPH2 and GOLPH3 play a role in melanoma progression and are potential targets for molecular-based therapies.

IgG subclass switching and clonal expansion in cutaneous melanoma and normal skin

B cells participate in immune surveillance in human circulation and tissues, including tumors such as melanoma. By contrast, the role of humoral responses in cutaneous immunity is underappreciated. We report circulating skin-homing CD22+CLA+B cells in healthy volunteers and melanoma patients (n = 73) and CD22+ cells in melanoma and normal skin samples (n = 189). Normal and malignant skin featured mature IgG and CD22 mRNA, alongside mRNA for the transiently-expressed enzyme Activation-induced cytidine Deaminase (AID). Gene expression analyses of publically-available data (n = 234 GEO, n = 384 TCGA) confirmed heightened humoral responses (CD20, CD22, AID) in melanoma. Analyses of 51 melanoma-associated and 29 normal skin-derived IgG sequence repertoires revealed lower IgG1/IgG_total representation compared with antibodies from circulating B cells. Consistent with AID, comparable somatic hypermutation frequencies and class-switching indicated affinity-matured antibodies in normal and malignant skin. A melanoma-associated antibody subset featured shorter complementarity-determining (CDR3) regions relative to those from circulating B cells. Clonal amplification in melanoma-associated antibodies and homology modeling indicated differential potential antigen recognition profiles between normal skin and melanoma sequences, suggesting distinct antibody repertoires. Evidence for IgG-expressing B cells, class switching and antibody maturation in normal and malignant skin and clonally-expanded antibodies in melanoma, support the involvement of mature B cells in cutaneous immunity.

The inextricable axis of targeted diagnostic imaging and therapy: An immunological natural history approach

In considering the challenges of approaches to clinical imaging, we are faced with choices that sometimes are impacted by rather dogmatic notions about what is a better or worse technology to achieve the most useful diagnostic image for the patient. For example, is PET or SPECT most useful in imaging any particular disease dissemination? The dictatorial approach would be to choose PET, all other matters being equal. But is such a totalitarian attitude toward imaging selection still valid? In the face of new receptor targeted SPECT agents one must consider the remarkable specificity and sensitivity of these agents. (99m)Tc-Tilmanocept is one of the newest of these agents, now approved for guiding sentinel node biopsy (SLNB) in several solid tumors. Tilmanocept has a Kd of 3×10(-11)M, and it specificity for the CD206 receptor is unlike any other agent to date. This coupled with a number of facts, that specific disease-associated macrophages express this receptor (100 to 150 thousand receptors), that the receptor has multiple binding sites for tilmanocept (>2 sites per receptor) and that these receptors are recycled every 15 min to bind more tilmanocept (acting as intracellular "drug compilers" of tilmanocept into non-degraded vesicles), gives serious pause as to how we select our approaches to diagnostic imaging. Clinically, the size of SLNs varies greatly, some, anatomically, below the machine resolution of SPECT. Yet, with tilmanocept targeting, the SLNs are highly visible with macrophages stably accruing adequate (99m)Tc-tilmanocept counting statistics, as high target-to-background ratios can compensate for spatial resolution blurring. Importantly, it may be targeted imaging agents per se, again such as tilmanocept, which may significantly shrink any perceived chasm between the imaging technologies and anchor the diagnostic considerations in the targeting and specificity of the agent rather than any lingering dogma about the hardware as the basis for imaging approaches. Beyond the elements of imaging applications of these agents is their evolution to therapeutic agents as well, and even in the neo-logical realm of theranostics. Characteristics of agents such as tilmanocept that exploit the natural history of diseases with remarkably high specificity are the expectations for the future of patient- and disease-centered diagnosis and therapy.

Drug-induced skin reactions: a pathologist viewpoint

Cutaneous drug reactions are common adverse effects that occur in about 2-3% of the hospitalized patients. They have both immunologic and non-immunologic underlying mechanisms. These reactions are clinically and histologically similar to dermatoses. Their significant clinical indicators include: history of drug intake, atypical clinical features and improvement after cessation of the offending drugs. Their diagnostic histological clues include the presence of mixed histological patterns, apoptotic keratinocytes, eosinophils (dermis and epidermis), papillary dermal edema and extravasations of erythrocytes. However, no single clinical or histological feature is specific of drug eruptions. This work attempts to classify the histomorphologic reactions to various drugs in defined categories for assistance in morphologic diagnosis.

B-1 cells promote immunosurveillance against murine melanoma in host absence of CCR5: new perspective in autologous vaccination therapy

Autologous vaccination with tumor-primed dendritic cells increases immune response against tumor, which seems to be improved in host absence of CCR5. Because B-1 lymphocytes modulate the activity of different immune cells, we decided to study their influence in the resistance against murine B16F10 melanoma in a CCR5 deprived environment. Adoptive transfer of peritoneal B-1 CCR5(+/+) lymphocytes to CCR5(-/-) animals inhibited the establishment of lung metastasis and melanoma cell growth, in comparison to saline-treated CCR5(-/-) mice. In loco cell analysis demonstrated that the adoptive transfer of B-1 CCR5(+/+) lymphocytes to CCR5 deficient host was associated with a more intense influx of T CD8(+) to tumor site, indicating that the presence of CCR5(+/+) B-1 cells in the tumor environment induces the migration of T CD8 CCR5(-/-) cells to the implantation site. To corroborate this idea, CCR5(-/-) mice were injected with non B-1 peritoneal cells from wild type (WT) mice before B16F10 inoculation. In this regimen, CCR5(-/-) mice were not protected from tumor growth reinforcing the idea that, in host absence of CCR5, B-1 cells are essential to confer tumor resistance. This work indicates that, in the host absence of CCR5, naive B-1 cells may activate CD8T lymphocytes thereby promoting tumor resistance. Our results strongly suggest that autologous vaccination with B-1 lymphocytes in combination with CCR5 antagonists can be an alternative approach to tumor therapy.

Oxidative stress in malignant melanoma enhances tumor necrosis factor-α secretion of tumor-associated macrophages that promote cancer cell invasion

AIMS

Malignant melanoma is well known for abundant reactive oxygen species (ROS) that exist in the primary tumor environment. Within this microenvironment, tumor-associated macrophages (TAMs) play substantial roles in multiple steps of tumor development in terms of tumor growth, invasion, and metastasis. We therefore aimed to determine whether this high-level ROS in primary melanoma is capable to promote tumor invasiveness by influencing TAM properties. Moreover, we wanted to further investigate probable underlying mechanisms.

RESULTS

We characterized malignant melanoma TAMs as a heterogeneous phenotype, which possesses both M1 and M2 markers. We also revealed a role for high-level intracellular ROS in enhancing proinvasion signature of TAMs by strongly increasing their tumor necrosis factor α secretion, which is possibly attributed to ROS-enhanced peroxisome proliferator-activated receptor γ (PPARγ) translocation mediated by MAPK/ERK kinase 1.

INNOVATION

This is the first study demonstrating that high levels of ROS in the primary melanoma environment can influence TAM behaviors. Furthermore, we are also the first to indentify that nucleus-to-cytoplasm translocation of PPARγ is significantly upregulated by ROS and responsible for the proinvasiveness capacity of melanoma TAMs.

CONCLUSION

Taken together, our data describe how a high level of ROS plays a critical role in enhancing the proinvasion characteristic of TAMs in malignant melanoma.

Immunomics in Skin Cancer - Improvement in Diagnosis, Prognosis and Therapy Monitoring

This review will focus on the elements of the skin’s immune system, immune cells and/or non-immune cells that support immune mechanisms, molecules with immune origin and/or immune functions that are involved in skin carcinogenesis. All these immune elements are compulsory in the development of skin tumors and/or sustainability of the neoplastic process. In this light, recent data gathered in this review will acknowledge all immune elements that contribute to skin tumorigenesis; moreover, they can serve as immune biomarkers. These immune markers can contribute to the diagnostic improvement, prognosis forecast, therapy monitoring, and even personalized therapeutical approach in skin cancer. Immune processes that sustain tumorigenesis in non-melanoma and melanoma skin cancers are described in the framework of recent data.

Crosstalk between B16 melanoma cells and B-1 lymphocytes induces global changes in tumor cell gene expression

The analysis of gene expression patterns in cancers has improved the understanding of the mechanisms underlying the process of metastatic progression. However, the acquisition of invasive behavior in melanoma is poorly understood. In melanoma, components of the immune system can contribute to tumor progression, and inflammatory cells can influence almost all aspects of cancer progression, including metastasis. Recent studies have attributed an important role to B-1 cells, a subset of B lymphocytes, in melanoma progression. In vitro interactions between B16 melanoma cells and B-1 lymphocytes lead to increased B16 cell metastatic potential, but the molecular changes induced by B-1 lymphocytes on B16 cells have not yet been elucidated. In this study, we used a microarray approach to assess the gene expression profile of B16 melanoma cells following contact with B-1 lymphocytes (B16B1). The microarray analysis identified upregulation in genes involved with metastatic progression, such as ctss, ccl5, cxcl2 and stat3. RT-qPCR confirmed this increase in mRNA expression in B16B1 samples. As previous studies have indicated that the ERK1/2 MAPK cascade is activated in melanoma cells following contact with B-1 lymphocytes, RT-qPCR was performed with RNA from melanoma cells before and after contacting B-1 cells and untreated or treated with ERK phosphorylation inhibitors. The results showed that the expression of stat3, ctss and cxcl2 increased in B16B1 but decreased following ERK1/2 MAPK inhibition. Ccl5 gene expression increased after contacting B-1 cells and was maintained at the same level following inhibitor treatment. Stat3 was verified and validated at the protein level by Western blot analysis. STAT3 expression was also significantly increased in B16B1, suggesting that this pathway can also contribute to the increased metastatic phenotype observed in our model. These results indicated that B-1 cells induce important global gene expression changes in B16 melanoma cells. We also evaluated the relationship of some of the genes identified as differentially expressed and the ERK1/2 MAPK cascade. This work may have important implications for understanding the role of B-1 lymphocytes and the ERK/MAPK cascade in the metastatic process.

Extravillous trophoblast and decidual natural killer cells: a remodelling partnership

BACKGROUND

During pregnancy, maternal uterine spiral arteries (SAs) are remodelled from minimal-flow, high-resistance vessels into larger diameter vessels with low resistance and high flow. Fetal extravillous trophoblasts (EVT) have important roles in this process. Decidual natural killer cells (dNK cells) are the major maternal immune component of the decidua and accumulate around SAs before trophoblast invasion. A role for dNK cells in vessel remodelling is beginning to be elucidated. This review examines the overlapping and dissimilar mechanisms used by EVT and dNK cells in this process and how this may mirror another example of tissue remodelling, namely cancer development.

METHODS

The published literature was searched using Pubmed focusing on EVT, dNK cells and SA remodelling. Additional papers discussing cancer development are also included.

RESULTS

Similarities exist between actions carried out by dNK cells and EVT. Both interact with vascular cells lining the SA, as well as with each other, to promote transformation of the SA. EVT differentiation has previously been likened to the epithelial-mesenchymal transition in cancer cells, and we discuss how dNK-EVT interactions at the maternal-fetal interface can also be compared with the roles of immune cells in cancer.

CONCLUSIONS

The combined role that dNK cells and EVT play in SA remodelling suggests that these interactions could be described as a partnership. The investigation of pregnancy as a multicellular system involving both fetal and maternal components, as well as comparisons to similar examples of tissue remodelling, will further identify the key mechanisms in SA remodelling that are required for a successful pregnancy.

Multiwalled carbon nanotubes interact with macrophages and influence tumor progression and metastasis

Macrophages are one of the most important types of immune effector cells and are closely associated with tumor progression and metastasis. In this work, we investigated the influences of oxidized multiwalled carbon nanotubes (o-MWCNT) on macrophages that are resting in the normal subcutis tissue or in the tumor microenvironment in vivo as well as on the macrophage cell line of RAW 264.7 treated with combination of IL4, IL10 and IL13 in vitro. The o-MWCNT were characterized with SEM, DLS, FTIR, TGA, and UV-vis-NIR spectroscopy, and their effects on the RWA 264.7 cell line and breast cancer tumor-bearing mice were analyzed using the MTS assay, flow cytometry analysis, and histological and immunohistochemical observations. Our experimental results showed that subcutaneously injected o-MWCNT not only induced phagocytosis of the local resident macrophages, but also competitively recruited macrophages from other tissues. These interactions resulted in macrophage reduction and decreased vessel density around the tumor mass, which together inhibited tumor progression and metastasis in the lung. In the cell line model, the o-MWCNT inhibited the ability of the interleukin treated RAW macrophages to promote tumor cell migration as well as decreased their proliferation rate.

Emerging roles of cathepsin E in host defense mechanisms

Cathepsin E is an intracellular aspartic proteinase of the pepsin superfamily, which is predominantly expressed in certain cell types, including the immune system cells and rapidly regenerating gastric mucosal and epidermal keratinocytes. The intracellular localization of this protein varies with different cell types. The endosomal localization is primarily found in antigen-presenting cells and gastric cells. The membrane association is observed with certain cell types such as erythrocytes, osteoclasts, gastric parietal cells and renal proximal tubule cells. This enzyme is also found in the endoplasmic reticulum, Golgi complex and cytosolic compartments in various cell types. In addition to its intracellular localization, cathepsin E occurs in the culture medium of activated phagocytes and cancer cells as the catalytically active enzyme. Its strategic expression and localization thus suggests the association of this enzyme with specific biological functions of the individual cell types. Recent genetic and pharmacological studies have particularly suggested that cathepsin E plays an important role in host defense against cancer cells and invading microorganisms. This review focuses emerging roles of cathepsin E in immune system cells and skin keratinocytes, and in host defense against cancer cells. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome.

Elevated expression of tumor necrosis factor-alpha signaling molecules in colonic tumors of Zucker obese (fa/fa) rats

Zucker obese rats are highly sensitive to colon cancer and possess a plethora of metabolic abnormalities including elevated levels of cytokine tumor necrosis factor-alpha (TNF-alpha). The main objective of this study was to determine if physiologically elevated TNF-alpha affects colonic tumor phenotype with regard to an altered TNF-alpha signaling pathway. Zucker obese (fa/fa, homozygous recessive for dysfunctional leptin receptors), Zucker lean (Fa/fa, Fa/Fa) and Sprague-Dawley (SD) rats were injected twice with azoxymethane (10 mg/kg) over 2 weeks. After 30 weeks, the animals were terminated and physiological and tumor parameters were assessed. Obese rats had notably higher body and organ weights as well as plasma TNF-alpha, insulin and leptin levels than lean or SD animals. A 100% tumor incidence and significantly higher tumor size, multiplicity and burden were found in obese rats compared to the lean group that had 47.8% tumor incidence. The SD group had the lowest tumor incidence (20.0%). Tumors from obese animals had higher protein levels of TNF-alpha, TNF-alpha-receptor-2 (TNFR2), nuclear transcription factor-kappaB (NF-kappaB) and IkappaB-kinasebeta (IKKbeta) compared to lean animals. In both obese and lean groups, expression levels of these proteins were higher in tumors than in surrounding, normal-appearing colonic mucosae. These findings support an important role for TNF-alpha signaling in tumorigenesis and demonstrate that tumors growing in an obese state had significantly different expression levels of TNFR2 and NF-kappaB, proteins known to play a critical role in growth and survival, than those growing in the lean state. It is concluded that the physiological state of the host intricately affects tumor phenotype.

The effect of monotherapy and combined therapy with NSC-631570 (ukrain) on growth of low- and high-metastasizing B16 melanoma in mice

BACKGROUND

NSC-631570 (ukrain) is a semisynthetic derivative of the Chelidonium majus alcaloids and the alkylans thiotepa. It exerts a selective cytotoxic effect on tumor cells in vitro and in vivo and shows the ability to modulate immunocyte functions. Purpose. The aim of our work was to carry out a comparative investigation of the effects of NSC-631570 alone or in combination with pathogen-associated molecules (PAM) on the growth of low- and high-metastasizing melanoma B16 in mice.

METHODS

NSC-631570 was administered intravenously and PAM intramuscularly to tumor-bearing mice seven times every third day, starting from the second day after the transplantation of tumor cells. The effect of monotherapy and combined therapy on tumor growth was evaluated by the indices of tumor growth inhibition in experimental animals. Cell cycle distribution of cancer cells was determined by flow cytometry. TAP1 and TAP2 expression was evaluated by RT-PCR. The metabolic activity of phagocytes was determined by NBT-test, phagocytosis was tested by flow cytometry, and arginase activity was estimated by colorimetric determination of urea.

RESULTS

Combined therapy and monotherapy with NSC-631570 resulted in significant inhibition of tumor growth in melanoma-bearing mice. Monotherapy with Ukrain was more effective in mice with high-metastasizing tumors. The therapeutic efficacy of NSC-631570 used in combination with PAM was more expressed in mice with low-metastasizing melanoma.

CONCLUSION

The effectiveness of monotherapy and combined therapy with NSC-631570 in the treatment of melanoma B16 depends on the biological properties of the tumor and the immune state of the organism.