Activin A Sustains the Metastatic Phenotype of Tumor-Associated Macrophages and Is a Prognostic Marker in Human Cutaneous Melanoma

Multiple Endocrine Neoplasia Type 1 Regulates TGFβ-Mediated Suppression of Tumor Formation and Metastasis in Melanoma

Over the past few decades, the worldwide incidence of cutaneous melanoma, a malignant neoplasm arising from melanocytes, has been increasing markedly, leading to the highest rate of skin cancer-related deaths. While localized tumors are easily removed by excision surgery, late-stage metastatic melanomas are refractory to treatment and exhibit a poor prognosis. Consequently, unraveling the molecular mechanisms underlying melanoma tumorigenesis and metastasis is crucial for developing novel targeted therapies. We found that the multiple endocrine neoplasia type 1 (MEN1) gene product Menin is required for the transforming growth factor beta (TGFβ) signaling pathway to induce cell growth arrest and apoptosis in vitro and prevent tumorigenesis in vivo in preclinical xenograft models of melanoma. We further identified point mutations in two MEN1 family members affected by melanoma that led to proteasomal degradation of the MEN1 gene product and to a loss of TGFβ signaling. Interestingly, blocking the proteasome degradation pathway using an FDA-approved drug and RNAi targeting could efficiently restore MEN1 expression and TGFβ transcriptional responses. Together, these results provide new potential therapeutic strategies and patient stratification for the treatment of cutaneous melanoma.

Immune Regulation and Immune Therapy in Melanoma: Review with Emphasis on CD155 Signalling

Melanoma is commonly diagnosed in a younger population than most other solid malignancies and, in Australia and most of the world, is the leading cause of skin-cancer-related death. Melanoma is a cancer type with high immunogenicity; thus, immunotherapies are used as first-line treatment for advanced melanoma patients. Although immunotherapies are working well, not all the patients are benefitting from them. A lack of a comprehensive understanding of immune regulation in the melanoma tumour microenvironment is a major challenge of patient stratification. Overexpression of CD155 has been reported as a key factor in melanoma immune regulation for the development of therapy resistance. A more thorough understanding of the actions of current immunotherapy strategies, their effects on immune cell subsets, and the roles that CD155 plays are essential for a rational design of novel targets of anti-cancer immunotherapies. In this review, we comprehensively discuss current anti-melanoma immunotherapy strategies and the immune response contribution of different cell lineages, including tumour endothelial cells, myeloid-derived suppressor cells, cytotoxic T cells, cancer-associated fibroblast, and nature killer cells. Finally, we explore the impact of CD155 and its receptors DNAM-1, TIGIT, and CD96 on immune cells, especially in the context of the melanoma tumour microenvironment and anti-cancer immunotherapies.

Chemokine profiling of melanoma-macrophage crosstalk identifies CCL8 and CCL15 as prognostic factors in cutaneous melanoma

During cancer evolution, tumor cells attract and dynamically interact with monocytes/macrophages. To find biomarkers of disease progression in human melanoma, we used unbiased RNA sequencing and secretome analyses of tumor-macrophage co-cultures. Pathway analysis of genes differentially modulated in human macrophages exposed to melanoma cells revealed a general upregulation of inflammatory hallmark gene sets, particularly chemokines. A selective group of chemokines, including CCL8, CCL15, and CCL20, was actively secreted upon melanoma-macrophage co-culture. Because we previously described the role of CCL20 in melanoma, we focused our study on CCL8 and CCL15 and confirmed that in vitro both chemokines contributed to melanoma survival, proliferation, and 3D invasion through CCR1 signaling. In vivo, both chemokines enhanced primary tumor growth, spontaneous lung metastasis, and circulating tumor cell survival and lung colonization in mouse xenograft models. Finally, we explored the clinical significance of CCL8 and CCL15 expression in human skin melanoma, screening a collection of 67 primary melanoma samples, using multicolor fluorescence and quantitative image analysis of chemokine-chemokine receptor content at the single-cell level. Primary skin melanomas displayed high CCR1 expression, but there was no difference in its level of expression between metastatic and nonmetastatic cases. By contrast, comparative analysis of these two clinically divergent groups showed a highly significant difference in the cancer cell content of CCL8 (p = 0.025) and CCL15 (p < 0.0001). Kaplan-Meier curves showed that a high content of CCL8 or CCL15 in cancer cells correlated with shorter disease-free and overall survival (log-rank test, p < 0.001). Our results highlight the role of CCL8 and CCL15, which are highly induced by melanoma-macrophage interactions in biologically aggressive primary melanomas and could be clinically applicable biomarkers for patient profiling. © 2024 The Pathological Society of Great Britain and Ireland.

Targeting tumor-associated macrophages: Novel insights into immunotherapy of skin cancer

BACKGROUND

The incidence of skin cancer is currently increasing, and conventional treatment options inadequately address the demands of disease management. Fortunately, the recent rapid advancement of immunotherapy, particularly immune checkpoint inhibitors (ICIs), has ushered in a new era for numerous cancer patients. However, the efficacy of immunotherapy remains suboptimal due to the impact of the tumor microenvironment (TME). Tumor-associated macrophages (TAMs), a major component of the TME, play crucial roles in tumor invasion, metastasis, angiogenesis, and immune evasion, significantly impacting tumor development. Consequently, TAMs have gained considerable attention in recent years, and their roles have been extensively studied in various tumors. However, the specific roles of TAMs and their regulatory mechanisms in skin cancer remain unclear.

AIM OF REVIEW

This paper aims to elucidate the origin and classification of TAMs, investigate the interactions between TAMs and various immune cells, comprehensively understand the precise mechanisms by which TAMs contribute to the pathogenesis of different types of skin cancer, and finally discuss current strategies for targeting TAMs in the treatment of skin cancer.

KEY SCIENTIFIC CONCEPTS OF OVERVIEW

With a specific emphasis on the interrelationship between TAMs and skin cancer, this paper posits that therapeutic modalities centered on TAMs hold promise in augmenting and harmonizing with prevailing clinical interventions for skin cancer, thereby charting a novel trajectory for advancing the landscape of immunotherapeutic approaches for skin cancer.

Organogermanium THGP Induces Differentiation into M1 Macrophages and Suppresses the Proliferation of Melanoma Cells via Phagocytosis

M1 macrophages are an important cell type related to tumor immunology and are known to phagocytose cancer cells. In previous studies, the organogermanium compound poly-trans-[(2-carboxyethyl)germasesquioxane] (Ge-132) and its hydrolysate, 3-(trihydroxygermyl) propanoic acid (THGP), have been reported to exert antitumor effects by activating NK cells and macrophages through the induction of IFN-γ activity in vivo. However, the detailed molecular mechanism has not been clarified. In this study, we found that macrophages differentiate into the M1 phenotype via NF-κB activation under long-term culture in the presence of THGP in vitro and in vivo. Furthermore, long-term culture with THGP increases the ability of RAW 264.7 cells to suppress B16 4A5 melanoma cell proliferation. These mechanisms indicate that THGP promotes the M1 polarization of macrophages and suppresses the expression of signal-regulatory protein alpha (SIRP-α) in macrophages and CD47 in cancers. Based on these results, THGP may be considered a new regulatory reagent that suppresses tumor immunity.

Dual-labeled nanoparticles based on small extracellular vesicles for tumor detection

Background

Small extracellular vesicles (sEVs) are emerging natural nanoplatforms in cancer diagnosis and therapy, through the incorporation of signal components or drugs in their structure. However, for their translation into the clinical field, there is still a lack of tools that enable a deeper understanding of their in vivo pharmacokinetics or their interactions with the cells of the tumor microenvironment. In this study, we have designed a dual-sEV probe based on radioactive and fluorescent labeling of goat milk sEVs.

Results

The imaging nanoprobe was tested in vitro and in vivo in a model of glioblastoma. In vitro assessment of the uptake of the dual probe in different cell populations (RAW 264.7, U87, and HeLa) by optical and nuclear techniques (gamma counter, confocal imaging, and flow cytometry) revealed the highest uptake in inflammatory cells (RAW 264.7), followed by glioblastoma U87 cells. In vivo evaluation of the pharmacokinetic properties of nanoparticles confirmed a blood circulation time of ~ 8 h and primarily hepatobiliary elimination. The diagnostic capability of the dual nanoprobe was confirmed in vivo in a glioblastoma xenograft model, which showed intense in vivo uptake of the SEV-based probe in tumor tissue. Histological assessment by confocal imaging enabled quantification of tumor populations and confirmed uptake in tumor cells and tumor-associated macrophages, followed by cancer-associated fibroblasts and endothelial cells.

Conclusions

We have developed a chemical approach for dual radioactive and fluorescent labeling of sEVs. This methodology enables in vivo and in vitro study of these vesicles after exogenous administration. The dual nanoprobe would be a promising technology for cancer diagnosis and a powerful tool for studying the biological behavior of these nanosystems for use in drug delivery.

Graphical Abstract

Different Immunoregulation Roles of Activin A Compared With TGF-β

Activin A, a critical member of the transforming growth factor-β (TGF-β) superfamily, is a pluripotent factor involved in allergies, autoimmune diseases, cancers and other diseases with immune disorder. Similar to its family member, TGF-β, activin A also transmits signals through SMAD2/SMAD3, however, they bind to distinct receptors. Recent studies have uncovered that activin A plays a pivotal role in both innate and adaptive immune systems. Here we mainly focus its effects on activation, differentiation, proliferation and function of cells which are indispensable in the immune system and meanwhile make some comparisons with those of TGF-β.