Association of TYRP1 with hypoxia and its correlation with patient outcome in uveal melanoma

Prognostic significance of melanogenesis pathway and its association with the ultrastructural characterisation of melanosomes in uveal melanoma

BACKGROUND

Pigmentation could be a relevant prognostic factor in uveal melanoma (UM) development. Microphthalmia-associated transcription factor (MITF) regulates melanin synthesis by activating tyrosinase-related protein 2 (TYRP2) and silver protein (SILV) that induce the melanogenesis pathway. Although their oncogenic potential has been observed in various malignancies but has not been investigated in UM Asian population. Our aim is to study the ultrastructure of melanosomes and the prognostic significance of pigmentation markers such as TYRP2, MITF and SILV in UM.

METHODS

Transmission electron microscopy was performed to compare the ultrastructure of melanosomes in the normal choroid and UM cases. Immunoexpression of TYRP2, SILV and MITF was analysed in 82 UM samples. The mRNA expression level of all genes was measured in 70 UM cases. A statistical correlation was performed to determine the prognostic significance of all markers.

RESULTS

Premelanosomes and mature melanosomes undergoing dedifferentiation were observed in high-pigmented UM cases as compared with low-pigmented UM cases. Seventy per cent of UM cases showed high SILV expression while TYRP2 and MITF expression was present in 58% and 56% of cases, respectively. At the mRNA level, upregulation of TYRP2, SILV and MITF markers was seen in around 50% of UM cases, which was statistically significant with high pigmentation. Reduced metastatic-free survival was statistically significant with the MITF protein expression.

CONCLUSION

Our results demonstrated that ultrastructural changes in melanosomes and high expression of TYRP2, MITF and SILV could dysregulate the melanogenesis pathway and might be responsible for the aggressive behaviour of UM.

Integrated analyses of prognostic and immunotherapeutic significance of EZH2 in uveal melanoma

The EZH2 expression shows significantly associated with immunotherapeutic resistance in several tumors. A comprehensive analysis of the predictive values of EZH2 for immune checkpoint blockade (ICB) effectiveness in uveal melanoma (UM) remains unclear. We analyzed UM data from The Cancer Genome Atlas (TCGA) database, identified 888 differentially expressed genes (DEGs) associated with EZH2 expression, then conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses to elucidate biological features of EZH2 in UM assays. The correlation of the expression of EZH2 with tumor immunity related factors such as immune-related pathways, infiltration of various immune cells, immune score and immune checkpoints were explored. The evaluation of EZH2's capability to predict immune therapy outcomes in UM was assessed by incorporating the Tumor Immune Dysfunction and Exclusion (TIDE) score. Lastly, programmed death-ligand 1 (PD-L1) expression was detected in an independent UM patient cohort by immunohistochemical analyses, the correlation of EZH2 with PD-L1 was evaluated. Results highlighted that the EZH2 expression was correlated with immune-related pathways, infiltration of various immune cells, immune score, the expression of immune checkpoints and immunotherapy sensitivity. Collectively, we suggested that EZH2 might be considered as predictor on the therapeutic effects of ICBs on UM patients, and a potential target for combined immunotherapy.

[Choroidal neovascularization associated with choroidal nevi]

Choroidal neovascularization (CNV) is a pathological angiogenic process observed in various fundus diseases, including choroidal nevi. This article reviews key information on the pathogenesis of CNV associated with choroidal nevi, examines diagnostic methods using optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A), including modern classifications and criteria for assessing disease activity. The article also discusses approaches to the differential diagnosis of nevi combined with neovascular age-related macular degeneration, progressive nevi, and melanomas, and analyzes the features of treatment with antiangiogenic agents and their effects on pigmented choroidal lesions.

UBE2G2 inhibits vasculogenic mimicry and metastasis of uveal melanoma by promoting ubiquitination of LGALS3BP

Uveal melanoma (UM) poses a significant lethality, with approximately 50% of those developing metastases surviving less than one year. In the progression of UM, vasculogenic mimicry (VM) induced by hypoxia plays a pivotal role, which also partially explains the resistance of UM to anti-angiogenic therapies. Nevertheless, the crucial molecular mechanisms underlying VM in the progression of UM remain unclear. We identified ubiquitin conjugating enzyme E2 G2 (UBE2G2) as a critical suppressor through transcriptomic sequencing and metastasis correlation screening. In UM, hypoxia-induced VM and metastasis are markedly exacerbated by UBE2G2 knockdown and significantly alleviated by its overexpression. Mechanistically, UBE2G2 directly binds to galectin 3 binding protein (LGALS3BP) and forms a complex with the E3 ubiquitin ligase tripartite motif containing 38 (TRIM38), facilitating ubiquitination-mediated degradation of LGALS3BP at the K104 residue. Furthermore, UBE2G2 inhibits oncogenic phenotypes by inactivating intracellular PI3K/AKT signaling and reprogramming the tumor microenvironment. Therefore, targeting intercellular and intracellular molecular mechanisms of the hypoxia-UBE2G2-LGALS3BP axis may contribute to developing various therapeutic strategies for UM.

Deciphering the Intricate Relationship Between Macrophages, Pigmentation, and Prognosis in Uveal Melanoma

High pigmentation and the abundance of M2 macrophages have been identified as negative predictors in uveal melanoma (UM). Risk factors associated with UM that are prevalent in high-risk White populations are still present, although less common, in relatively low-risk Asian populations. Research indicates that proangiogenic M2 macrophages and monosomy 3 play significant roles in UM progression. Our aim was to investigate the impact of tumor-associated macrophages in UM and examine their correlation with monosomy 3 and pigmentation. Transmission electron microscopy was used to analyze the morphology of macrophages in UM. Forty UM samples underwent fluorescent in situ hybridization for monosomy 3 identification. Immunohistochemistry was done to assess M2/M1 macrophages on 82 UM tissue samples. IL-10 and IL-12 expressions were quantified in UM serum samples by enzyme-linked immunosorbent assay. The expression of all markers was correlated with pigmentation markers (tyrosinase-related protein 1, tyrosinase-related protein 2, silver protein, and microphthalmia-associated transcription factor). Prognostic outcomes were determined using the Cox proportional hazard model and log-rank tests. Increased expression of M2/M1 macrophages was observed in 31 UM cases, which correlated with the high expression of pigmentation markers. IL-10 concentration was high in UM cases. Monosomy 3 was evident in 50% of UM cases and significantly associated with increased immunoexpression of M2/M1 macrophages and pigmentation markers. Reduced metastasis-free survival was observed in patients with UM with high M2/M1 macrophage expression (P = .001). High pigmentation and increased M2 macrophage density could impact the tumor microenvironment in UM. This could contribute to ineffective antitumor immune responses in patients with UM. Our findings suggest avenues for developing novel therapeutic approaches to counteract these immunosuppressive effects in UM.

Complex Inhibitory Activity of Pentacyclic Triterpenoids against Cutaneous Melanoma In Vitro and In Vivo: A Literature Review and Reconstruction of Their Melanoma-Related Protein Interactome

Pentacyclic triterpenoids (PTs) are a class of plant metabolites with a wide range of pharmacological activities, including strong antitumor potential against skin malignancies. By acting on multiple signaling pathways that control key cellular processes, PTs are able to exert complex effects on melanoma progression in vitro and in vivo. In this review, we have analyzed the works published in the past decade and devoted to the effects of PTs, both natural and semisynthetic, on cutaneous melanoma pathogenesis, including not only their direct action on melanoma cells but also their influence on the tumor microenvironment and abberant melanogenesis, often associated with melanoma aggressiveness. Special attention will be paid to the molecular basis of the pronounced antimelanoma potency of PTs, including a detailed consideration of the pathways sensitive to PTs in melanoma cells, as well as the reconstruction of the melanoma-related protein interactome of PTs using a network pharmacology approach based on previously published experimentally verified protein targets of PTs. The information collected on the primary targets of PTs was compiled in the Protein Interactome of PTs (PIPTs) database, freely available at http://www.pipts-db.ru/, which can be used to further optimize the mechanistic studies of PTs in the context of melanoma and other malignancies. By summarizing recent research findings, this review provides valuable information to scientists working in the fields related to the evaluation of melanoma pathogenesis and development of PTs-based drug candidates.

Epidemiology and tumor microenvironment of ocular surface and orbital tumors on growth and malignant transformation

The ocular surface and orbit constitute unique microenvironments in the human body. Current advances in molecular research have deepened our understanding of tumor development in these regions. Tumors exhibit greater heterogeneity compared to normal tissues, as revealed by pathological and histological examinations. The tumor microenvironment (TME) plays a crucial role in the proliferation and progression of cancer cells. Factors from the external environment or the body's own inflammation and microcirculation interact within the TME, maintaining a delicate balance. Disruption of this balance, through uncontrolled signal pathway activation, can transform normal or benign tissues into malignant ones. In recent years, various systemic immunotherapies have been developed for cancer treatment. This study reviews the epidemiology of ocular surface and orbital tumors include squamous cell carcinoma, basal cell carcinoma, sebaceous carcinoma and lymphoma in conjunction with their occurrence, growth, and underlying mechanisms. We propose that by examining clinical histopathological images, we can identify specific and shared microscopic features of tumors. By collecting, classifying, and analyzing data from these clinical histopathological images, we can pinpoint independent diagnostic factors characteristic of tumors. We hope this study provides a basis for future exploration of the mechanisms underlying different ocular diseases.

Phase 1, first-in-human study of TYRP1-TCB (RO7293583), a novel TYRP1-targeting CD3 T-cell engager, in metastatic melanoma: active drug monitoring to assess the impact of immune response on drug exposure

Introduction

Although checkpoint inhibitors (CPIs) have improved outcomes for patients with metastatic melanoma, those progressing on CPIs have limited therapeutic options. To address this unmet need and overcome CPI resistance mechanisms, novel immunotherapies, such as T-cell engaging agents, are being developed. The use of these agents has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs), which is challenging to predict preclinically and can lead to neutralization of the drug and loss of efficacy.

Methods

TYRP1-TCB (RO7293583; RG6232) is a T-cell engaging bispecific (TCB) antibody that targets tyrosinase-related protein 1 (TYRP1), which is expressed in many melanomas, thereby directing T cells to kill TYRP1-expressing tumor cells. Preclinical studies show TYRP1-TCB to have potent anti-tumor activity. This first-in-human (FIH) phase 1 dose-escalation study characterized the safety, tolerability, maximum tolerated dose/optimal biological dose, and pharmacokinetics (PK) of TYRP1-TCB in patients with metastatic melanoma (NCT04551352).

Results

Twenty participants with cutaneous, uveal, or mucosal TYRP1-positive melanoma received TYRP1-TCB in escalating doses (0.045 to 0.4 mg). All participants experienced ≥1 treatment-related adverse event (TRAE); two participants experienced grade 3 TRAEs. The most common toxicities were grade 1-2 cytokine release syndrome (CRS) and rash. Fractionated dosing mitigated CRS and was associated with lower levels of interleukin-6 and tumor necrosis factor-alpha. Measurement of active drug (dual TYPR1- and CD3-binding) PK rapidly identified loss of active drug exposure in all participants treated with 0.4 mg in a flat dosing schedule for ≥3 cycles. Loss of exposure was associated with development of ADAs towards both the TYRP1 and CD3 domains. A total drug PK assay, measuring free and ADA-bound forms, demonstrated that TYRP1-TCB-ADA immune complexes were present in participant samples, but showed no drug activity in vitro.

Discussion

This study provides important insights into how the use of active drug PK assays, coupled with mechanistic follow-up, can inform and enable ongoing benefit/risk assessment for individuals participating in FIH dose-escalation trials. Translational studies that lead to a better understanding of the underlying biology of cognate T- and B-cell interactions, ultimately resulting in ADA development to novel biotherapeutics, are needed.

The development and experimental validation of hypoxia-related long noncoding RNAs prognostic signature in predicting prognosis and immunotherapy of cutaneous melanoma

Cutaneous melanoma (CM) is widely acknowledged as a highly aggressive form of malignancy that is associated with a considerable degree of morbidity and poor prognosis. Despite this recognition, the precise role of hypoxia-related long noncoding RNAs (HRLs) in the pathogenesis of CM remains an area of active research. This study sought to elucidate the contribution of HRLs in CM by conducting a thorough screening and extraction of hypoxia-related genes (HRGs). In particular, we conducted univariate and multivariate Cox regression analyses to assess the independence of the prognostic signature of HRLs. Our results demonstrated that a novel risk model could be established based on five prognostic HRLs. Remarkably, patients with low-risk scores exhibited significantly higher overall survival rates compared to their high-risk counterparts, as confirmed by Kaplan-Meier survival analysis. Furthermore, we utilized consensus clustering analysis to categorize CM patients into two distinct subtypes, which revealed marked differences in their prognosis and immune infiltration landscapes. Our nomogram results confirmed that the HRLs prognostic signature served as an independent prognostic indicator, offering an accurate evaluation of the survival probability of CM patients. Notably, our findings from ESTIMATE and ssGSEA analyses highlighted significant disparities in the immune infiltration landscape between low- and high-risk groups of CM patients. Additionally, IPS and TIDE results suggested that CM patients in different risk subtypes may exhibit favorable responses to immunotherapy. Enrichment analysis and GSVA results indicated that immune-related signaling pathways may mediate the role of HRLs in CM. Finally, our tumor mutation burden (TMB) results indicated that patients with low-risk scores had a higher TMB status. In summary, the establishment of a risk model based on HRLs in this study provided an accurate prognostic prediction and correlated with the immune infiltration landscape of CM, thereby providing novel insights for the future clinical management of this disease.

Immuno-oncology approaches in uveal melanoma: tebentafusp and beyond

Uveal melanoma (UM) is the most common ocular malignancy in adults, associated with the poorest prognosis, with metastatic disease occurring in up to 50% of patients. In contrast to metastatic cutaneous melanoma, the use of immune checkpoint inhibitors is associated with poor outcomes in metastatic uveal melanoma (mUM). Tebentafusp, a bispecific molecule, has recently become the first treatment in decades to improve overall survival for mUM. This review summarises the existing and emerging immuno-oncology approaches for the treatment of mUM, and biomarkers of response and resistance to the same. Finally, we propose future research directions that could maximise treatment benefit to a wider pool of patients with UM.

TYRP1 Protects Against the Apoptosis and Oxidative Stress of Retinal Ganglion Cells by Binding to PMEL

OBJECTIVES

This research aimed to dissect the function of TYRP1 and PMEL in glaucomatous animal and cell models.

METHODS

A chronic ocular hypertension (COH) rat model was induced in the right eyes of rats through the electrocoagulation of superficial iris veins. In addition, an oxygen-glucose deprivation (OGD)-retinal ganglion cell (RGC) model was constructed through OGD. TYRP1 and PMEL expression was altered in the animal and cell models to explore their effects.

RESULTS

TYRP1 and PMEL expression was poor in glaucoma patients, COH rats, and OGD-RGCs. Mechanistically, TYRP1 interacted with PMEL to upregulate PMEL in OGD-RGCs. TYRP1 overexpression enhanced viability and diminished apoptosis and oxidative stress of OGD-RGCs, which was abolished by PMEL knockdown. TYRP1 upregulation reduced intraocular pressure, RGC apoptosis, and oxidative stress in COH rats, which was reversed by PMEL knockdown.

CONCLUSIONS

TYRP1 elevates PMEL expression to reduce RGC apoptosis and oxidative stress in vivo and in vitro.

Using the Chick Embryo Model to Examine the Effects of Hypoxia Pre-conditioning of Uveal Melanoma Cells on Tumor Growth and Metastasis

PURPOSE

Highly dynamic oxygen gradients occur within tumors that can result in a hypoxic response, contributing to tumor progression and metastasis. Evidence in uveal melanoma (UM) suggests an upregulated hypoxia response in some poor prognosis UM characterized by HIF1α signaling. We aimed to investigate the effects of exposure to hypoxia on tumor growth and dissemination in the chick embryo chorioallantoic membrane (CAM) model.

METHODS

UM cell lines (MP41, 92.1, MP46, and OMM1) were grown in two-dimensional culture and pre-exposed to hypoxic (1% O₂) conditions for 72 h. The effects of this hypoxia pre-conditioning on cell number and clonogenicity as compared with 21% O₂ ("normoxia") were investigated prior to transplantation of the cells onto the CAM. Nodule-forming efficiency (NFE), nodule size, and the presence/absence of tumor cell dissemination were determined macroscopically and histologically.

RESULTS

Exposure of UM cell lines to hypoxia upregulated HIF1α expression compared to cells cultured in normoxia. A 72-h pre-exposure to hypoxia significantly reduced cell number and clonogenicity in the MP41 and OMM1 cell lines while it had little effect in 92.1 and MP46 cells. When 72-h hypoxia pre-conditioned cells were grown in three-dimensions on the CAM, a reduction in NFE and nodule size was observed when compared with normoxic UM cells. All nodules were composed of proliferating (Ki-67+) Melan-A + cells and displayed chick blood vessel recruitment. Spread of UM cells into the adjacent CAM was observed; however, dissemination to the chick liver was only seen with 92.1 cells grown under normoxia.

CONCLUSIONS

Hypoxia pre-conditioning does not appear to drive a metastatic phenotype in UM; however, further understanding of how oxygen dynamics within the tumor microenvironment regulates HIF1 signaling is needed to determine whether inhibitors of HIF signaling represent a therapeutic option in metastatic UM.

The potential impact of melanosomal pH and metabolism on melanoma

Melanin is synthesized in melanocytes and is transferred into keratinocytes to block the effects of ultraviolet (UV) radiation and is important for preventing skin cancers including melanoma. However, it is known that after melanomagenesis and melanoma invasion or metastases, melanin synthesis still occurs. Since melanoma cells are no longer involved in the sun tanning process, it is unclear why melanocytes would maintain melanin synthesis after melanomagenesis has occurred. Aside from blocking UV-induced DNA mutation, melanin may provide other metabolic functions that could benefit melanoma. In addition, studies have suggested that there may be a selective advantage to melanin synthesis in melanoma; however, mechanisms regulating melanin synthesis outside the epidermis or hair follicle is unknown. We will discuss how melanosomal pH controls melanin synthesis in melanocytes and how melanosomal pH control of melanin synthesis might function in melanoma. We will also discuss potential reasons why melanin synthesis might be beneficial for melanoma cellular metabolism and provide a rationale for why melanin synthesis is not limited to benign melanocytes.