STAT6/LINC01637 axis regulates tumor growth via autophagy and pharmacological targeting STAT6 as a novel strategy for uveal melanoma

Compelling evidence has revealed a novel function of the STAT pathway in the pathophysiology of uveal melanoma (UM); however, its regulatory mechanisms remain unclear. Here, we analyzed the clinical prognostic value of STAT family genes in UM patients using bioinformatics approaches and found that high STAT6 expression is associated with poor prognosis. Furthermore, cellular experiments and a nude mouse model demonstrated that STAT6 promotes UM progression through the autophagy pathway both in vivo and in vitro. Next, RIP-PCR revealed that STAT6 protein binds to LINC01637 mRNA, which in turn regulates STAT6 expression to promote UM growth. Finally, molecular docking indicated that STAT6 is a target of Zoledronic Acid, which can delay UM tumorigenicity by inhibiting STAT6 expression. Taken together, our results indicate that the STAT6/LINC01637 axis promotes UM progression via autophagy and may serve as a potential therapeutic target for UM.

Expression of Markers Associated with Epithelial-Mesenchymal Transition and Extracellular Matrix Degradation in Human Uveal Melanoma

The expression of markers associated with epithelial-mesenchymal transition (EMT) and extracellular matrix degradation in human uveal melanoma tissue samples and postequatorial zone of the choroid was assessed by immunohistochemical staining. Increased expression of EMT markers E-cadherin and vimentin was observed in the tumor. The ratio of MMP-9 to TIMP-1 proteins related to the extracellular matrix degradation was higher in the tumor. These results may indicate activation of EMT-like process in the uveal melanoma cells and degradation of the extracellular matrix, which can contribute to the development of collective invasion in uveal melanoma.

Single-cell characterization of macrophages in uveal melanoma uncovers transcriptionally heterogeneous subsets conferring poor prognosis and aggressive behavior

Uveal melanoma (UM) is the most frequent primary intraocular malignancy with high metastatic potential and poor prognosis. Macrophages represent one of the most abundant infiltrating immune cells with diverse functions in cancers. However, the cellular heterogeneity and functional diversity of macrophages in UM remain largely unexplored. In this study, we analyzed 63,264 single-cell transcriptomes from 11 UM patients and identified four transcriptionally distinct macrophage subsets (termed MΦ-C1 to MΦ-C4). Among them, we found that MΦ-C4 exhibited relatively low expression of both M1 and M2 signature genes, loss of inflammatory pathways and antigen presentation, instead demonstrating enhanced signaling for proliferation, mitochondrial functions and metabolism. We quantified the infiltration abundance of MΦ-C4 from single-cell and bulk transcriptomes across five cohorts and found that increased MΦ-C4 infiltration was relevant to aggressive behaviors and may serve as an independent prognostic indicator for poor outcomes. We propose a novel subtyping scheme based on macrophages by integrating the transcriptional signatures of MΦ-C4 and machine learning to stratify patients into MΦ-C4-enriched or MΦ-C4-depleted subtypes. These two subtypes showed significantly different clinical outcomes and were validated through bulk RNA sequencing and immunofluorescence assays in both public multicenter cohorts and our in-house cohort. Following further translational investigation, our findings highlight a potential therapeutic strategy of targeting macrophage subsets to control metastatic disease and consistently improve the outcome of patients with UM.

Ultrasound-enhanced nano catalyst with ferroptosis-apoptosis combined anticancer strategy for metastatic uveal melanoma

Uveal melanoma is the most common primary ocular tumor owing to its highly invasive and metastatic characteristics. Currently, standard clinical treatment has an unsatisfied curative effect due to the lack of an effective approach to inhibit the tumor metastasis. Therefore, it is necessary to develop a new strategy that can both restraint local tumors and suppress the ocular tumor metastasis. Herein, we developed ultrasound-responsive nanoparticles (FeP NPs) that can both hinder the growth of in situ ocular tumor and prevent the tumor metastasis through the ferroptosis-apoptosis combined-anticancer strategy. The FeP NPs were assembling by stimulating gallic acid-Fe (III) and paclitaxel, then could be internalized into tumor cells under the cooperative effect of ultrasound, which further activates the intracellular Fenton reaction and generates high reactive oxygen species levels, ultimately leading to mitochondrial damage, lipid per-oxidation, and apoptosis. The FeP NPs can efficiently inhibit the tumor growth in an orthotopic uveal melanoma model. More importantly, the level of the promoting-metastatic factor nerve growth factor receptor (NGFR) secreted by cancer cells is significantly reduced, further limits cancer metastasis to the cervical lymph node and finally inhibits lung metastasis of uveal melanoma. We believe that these designed ultrasound-enhanced nanoparticles possess potential clinical application for preventing the regeneration and metastasis of uveal melanoma.

High-throughput chemogenetic drug screening reveals PKC-RhoA/PKN as a targetable signaling vulnerability in GNAQ-driven uveal melanoma

Uveal melanoma (UM) is the most prevalent cancer of the eye in adults, driven by activating mutation of GNAQ/GNA11; however, there are limited therapies against UM and metastatic UM (mUM). Here, we perform a high-throughput chemogenetic drug screen in GNAQ-mutant UM contrasted with BRAF-mutant cutaneous melanoma, defining the druggable landscape of these distinct melanoma subtypes. Across all compounds, darovasertib demonstrates the highest preferential activity against UM. Our investigation reveals that darovasertib potently inhibits PKC as well as PKN/PRK, an AGC kinase family that is part of the "dark kinome." We find that downstream of the Gαq-RhoA signaling axis, PKN converges with ROCK to control FAK, a mediator of non-canonical Gαq-driven signaling. Strikingly, darovasertib synergizes with FAK inhibitors to halt UM growth and promote cytotoxic cell death in vitro and in preclinical metastatic mouse models, thus exposing a signaling vulnerability that can be exploited as a multimodal precision therapy against mUM.

Design, synthesis and evaluation of quinazoline derivatives as Gαq/11 proteins inhibitors against uveal melanoma

Uveal melanoma (UM) represents the predominant ocular malignancy among adults, exhibiting high malignancy and proclivity for liver metastasis. GNAQ and GNA11 encoding Gαq and Gα11 proteins are key genes to drive UM, making the selective inhibition of Gαq/11 proteins to be a potential therapeutic approach for combating UM. In this study, forty-six quinazoline derivatives were designed, synthesized, and assessed for their ability to inhibit Gαq/11 proteins and UM cells. Compound F33 emerged as the most favorable candidate, and displayed moderate inhibitory activity against Gαq/11 proteins (IC50 = 9.4 μM) and two UM cell lines MP41 (IC50 = 6.7 μM) and 92.1 (IC50 = 3.7 μM). Being a small molecule inhibitor of Gαq/11 proteins, F33 could effectively suppress the activation of downstream signaling pathways in a dose-dependent manner, and significantly inhibits UM in vitro.F33 represents a promising lead compound for developing therapeutics for UM by targeting Gαq/11 proteins.

Systems modeling of oncogenic G-protein and GPCR signaling reveals unexpected differences in downstream pathway activation

Mathematical models of biochemical reaction networks are an important and emerging tool for the study of cell signaling networks involved in disease processes. One promising potential application of such mathematical models is the study of how disease-causing mutations promote the signaling phenotype that contributes to the disease. It is commonly assumed that one must have a thorough characterization of the network readily available for mathematical modeling to be useful, but we hypothesized that mathematical modeling could be useful when there is incomplete knowledge and that it could be a tool for discovery that opens new areas for further exploration. In the present study, we first develop a mechanistic mathematical model of a G-protein coupled receptor signaling network that is mutated in almost all cases of uveal melanoma and use model-driven explorations to uncover and explore multiple new areas for investigating this disease. Modeling the two major, mutually-exclusive, oncogenic mutations (Gαq/11 and CysLT2R) revealed the potential for previously unknown qualitative differences between seemingly interchangeable disease-promoting mutations, and our experiments confirmed oncogenic CysLT2R was impaired at activating the FAK/YAP/TAZ pathway relative to Gαq/11. This led us to hypothesize that CYSLTR2 mutations in UM must co-occur with other mutations to activate FAK/YAP/TAZ signaling, and our bioinformatic analysis uncovers a role for co-occurring mutations involving the plexin/semaphorin pathway, which has been shown capable of activating this pathway. Overall, this work highlights the power of mechanism-based computational systems biology as a discovery tool that can leverage available information to open new research areas.

Structure prediction of novel isoforms from uveal melanoma by AlphaFold

Alternative splicing is an important mechanism that enhances protein functional diversity. To date, our understanding of alternative splicing variants has been based on mRNA transcript data, but due to the difficulty in predicting protein structures, protein tertiary structures have been largely unexplored. However, with the release of AlphaFold, which predicts three-dimensional models of proteins, this challenge is rapidly being overcome. Here, we present a dataset of 315 predicted structures of abnormal isoforms in 18 uveal melanoma patients based on second- and third-generation transcriptome-sequencing data. This information comprises a high-quality set of structural data on recurrent aberrant isoforms that can be used in multiple types of studies, from those aimed at revealing potential therapeutic targets to those aimed at recognizing of cancer neoantigens at the atomic level.

Phenotypic Biomarkers of Aqueous Extracellular Vesicles from Retinoblastoma Eyes

Recent advancements in aqueous humor (AH) cell-free DNA (cfDNA) genomics have opened new avenues for ex vivo molecular profiling of retinoblastoma (RB), the most common pediatric intraocular malignancy, where biopsy is typically prohibited. While these insights offer a genetic blueprint of the tumor, they lack multi-omic molecular phenotyping, which is essential for understanding the functional state. Extracellular vesicles (EVs), naturally present in AH, are promising by offering time-resolved phenotypic information. We employed multiplex bead-based flow cytometry and Single Extracellular Vesicle Nanoscopy (SEVEN) to analyze EV phenotypes in AH from a cohort of five RB, with three uveal melanoma (UM) and two age-matched glaucoma (GLC) samples serving as controls. The studies identified CD133-enriched EVs uniquely in RB AH, absent in both GLC and UM AH. This was corroborated by further analysis of five RB cell lines, including two commercial (Y79, Weri) and three in-house developed lines, confirming CD133 enrichment and supporting its role as an RB-specific EV marker. Single-vesicle analysis demonstrated a strong association of CD133 with CD81 and CD63, with minimal CD9 presence. These results, validated through complementary techniques, position CD133 as a critical marker in RB-derived EVs, paving the way for enhanced multi-omic RB characterization and potential advancements in clinical diagnostics.

Comparative analysis of proliferating cell nuclear antigen, bromodeoxyuridine, and mitotic index in uveal melanoma

PURPOSE

Recent production of a monoclonal antibody, PC10, against proliferating cell nuclear antigen (PCNA) makes it possible to evaluate cell cycling in formalin-fixed tissues. In this study, the authors quantitatively evaluated the relationship between PCNA expression and two other measures of cell cycling, bromodeoxyuridine labeling index (BrdU LI) and mitotic index (MI), in archival uveal melanomas. The authors also examined the relative prognostic importance of each measure.

METHODS

Serial sections from 35 formalin-fixed, paraffin-embedded uveal melanomas were immunostained with PC10 and BrdU antibody using a standard avidin-biotin-peroxidase method. A quantitative scoring system was used to evaluate the fraction of cells that were positive for PCNA, BrdU, and mitotic figures in the regions of high cycling. The LIs of the different markers were compared, and their prognostic importance was evaluated.

RESULTS

The median PCNA LI was 3.05% compared to the median BrdU LI of 0.94% and the median MI of 0.034%. The PCNA LI was more variable in replicate sections than either the MI or the BrdU LI. The correlation between PCNA LI and BrdU LI was 0.58, between PCNA LI and MI it was 0.46, and between BrdU LI and MI it was 0.81. The relative risk of tumor-related mortality per doubling of BrdU LI was 2.35, and of MI it was 2.34. Although these were significant, PCNA LI of 1.08 was not.

CONCLUSIONS

Proliferating cell nuclear antigen immunostaining did not demonstrate a strong relationship with either BrdU LI or MI. Unlike MI and BrdU LI, PCNA LI was not correlated with tumor-related mortality. Caution is warranted in the interpretation of PCNA immunostaining in uveal melanomas.

Expression of Caveolin-1 in Human Cutaneous and Uveal Melanoma Cells

Caveolin-1 can act as a tumour promoter or suppressor depending on the cancer type and stage. In melanoma, information available concerning its expression is ambiguous. In this study, we investigated caveolin-1 mRNA and protein expression levels in human melanoma cell lines of different origin and progression stages. Metastatic cutaneous (WM-266-4, A375), primary cutaneous (WM- 115, IGR-39) and primary uveal (mel-202, 92-1) cells were used for quantitative RT-PCR, Western blotting and confocal microscopy. We observed significantly higher expression of caveolin-I mRNA in cutaneous than in uveal melanoma cells. In accordance, immunostaining of caveolin-I was stronger in cutaneous cell extracts, while protein bands of uveal origin displayed weak signals. Finally, we detected differences in the caveolin-I subcellular pattern of distribution between primary and metastatic cells. Overall, this is the first demonstration of caveolin-1 expression in human primary uveal melanoma cell lines and observation that the origin of cells (uveal/cutaneous) has an impact when considering the utility of caveolin-I as a melanoma cell marker.

[Clinicopathological significance of expression of IGF-1R in uveal melanoma and its association with expression of p-AKT Thr308]

OBJECTIVE

To investigate the clinicopathological significance of expression of insulin-like growth factor-1 receptor (IGF-1R) and its association with the expression of p-AKT Thr308 in uveal melanoma.

METHODS

Experimental study. Twenty-four patients with uveal melanoma were included from January 2000 to December 2008. The levels of IGF-1R and p-AKT Thr308 were detected by immunohistochemical methods, and their association with clinicopathological parameters including localization of tumor, tumor size, largest tumor diameters, cell type, necrosis, degree of pigmentation, lymphocyte infiltration, mitosis rate, scleral invasion and liver metastasis were statistically analyzed. The relationship of expression of IGF-1R with clinicopathological parameters or with the expression of p-AKT Thr308 was analyzed by chi-square test.

RESULTS

The positive rate of expression of IGF-1R in 24 cases of uveal melanoma was 75%. The expression of IGF-1R were associated with the largest tumor diameters, degree of pigmentation, liver metastasis and lymphocyte infiltration (χ(2) = 15.569, P = 0.016; χ(2) = 11.348, P = 0.010; χ(2) = 8.738, P = 0.033; χ(2) = 8.362, P = 0.039). The positive rate of expression of p-AKT Thr308 was 58%. The expression of IGF-1R and p-AKT Thr308 was positively correlated (χ(2) = 17.108, P = 0.009).

CONCLUSION

IGF-1R plays a role in the development of uveal melanoma which may be induced by activation in PI3K/AKT pathway.

Evaluation of the effects of vitamin D analogs, bevacizumab, and radiotherapy in uveal melanoma cells

Due to the lack of a definitive effective treatment method that provides a complete cure and increases survival rates in uveal melanoma, the search for alternative treatments at the molecular level continues. In this context, we aimed to comparatively analyze the therapeutic effects of 25-hydroxyvitamin D3 (D2), 1a, 25-dihydroxyvitamin D3 (D3), bevacizumab and radiotherapy (RT) in a uveal melanoma cell line (MP41). Cytotoxicity was evaluated using XTT cell proliferation kit and Xcelligence cell analyzer system. RT dose was determined after a clonogenic assay. Annexin V/PI staining and Western blot analyses for caspase-3, -8, and -9 were performed to analyze apoptosis. Additionally, cell cycle analyses were also conducted. As a result, we found that D2 and D3 did not show cytotoxic effects, while bevacizumab and RT showed time and dose-dependent cytotoxicity. IC50 concentration of bevacizumab was 6.945 mg/mL. Radiotherapy and bevacizumab significantly reduced cell survival and induced apoptosis when administered both as monotherapy and in combination. A significant increase in caspase proteins was detected at high bevacizumab concentrations. However, the combination of bevacizumab and radiotherapy caused a substantial decrease in caspase-3, -8 and -9 expressions. No significant difference in cell cycle distribution was detected in any treatment. Our results showed that bevacizumab inhibited MP41 cell proliferation and had an additive effect when administered with RT. In conclusion, our study offers a different perspective on the treatment of uveal melanoma, and these results, when supported by animal experiments and clinical studies in the future, might be a new step in the treatment of this challenging ocular tumor.

Integration of Bulk RNA Sequencing and Single-Cell RNA Sequencing to Reveal Uveal Melanoma Tumor Heterogeneity and Cells Related to Survival

Molecular classification based on transcriptional characteristics is often used to study tumor heterogeneity. Human cancer has different cell populations with distinct transcription in tumors, and their heterogeneity is the focus of tumor therapy. Our purpose was to explore the tumor heterogeneity of uveal melanoma (UM) through RNA sequencing (RNA-seq) and single-cell RNA sequencing (scRNA-seq). Based on the consensus clustering assays of the prognosis-related immune gene set, the immune subtype (IS) of UM and its corresponding immune characteristics were comprehensively analyzed. The heterogeneous cell groups and corresponding marker genes of UM were identified from GSE138433 using scRNA-seq analysis. Pseudotime trajectory analysis and SCENIC analysis were conducted to explore the trajectory of cell differentiation and the regulatory network of single-cell transcription factors (TFs). Based on 37 immune gene sets, UM was divided into two different immune subtypes (IS1 and IS2). The two kinds of ISs have different characteristics in prognosis, immune-related molecules, immune score, and immune cell infiltration. According to 11,988 cells of scRNA-seq data from six UM samples, 11 cell clusters and 10 cell types were identified. The subsets of C1, C4, C5, C8, and C9 were related to the prognosis of UM, and different TF–target gene regulatory networks were involved. These five cell subsets differentiated into 3 different states. Our results provided valuable information about the heterogeneity of UM tumors and the expression patterns of TFs in different cell types.

ZNF197-AS1/miR-425/GABARAPL1 axis: a novel regulatory mechanism in uveal melanoma

This study investigates the role of the long noncoding RNA (lncRNA) ZNF197-AS1 in uveal melanoma (UM), focusing on its function within a competing endogenous RNA (ceRNA) network. Using the UM-related TCGA (The Cancer Genome Atlas) dataset, we analyzed the expression levels of ZNF197-AS1 and its correlation with miR-425 and GABARAPL1, an essential autophagy-related gene. Our analysis revealed that ZNF197-AS1 acts as a ceRNA by competitively binding to miR-425, resulting in the upregulation of GABARAPL1. This interaction plays a crucial role in the growth and metastasis of UM. The expression of GABARAPL1 showed a strong correlation with the clinical outcomes of patients with UM. Furthermore, in vitro assays confirmed that ZNF197-AS1 impedes UM cell proliferation, migration, and invasion by modulating the miR-425/GABARAPL1 axis. These findings suggest that ZNF197-AS1 can effectively inhibit UM progression through this ceRNA regulatory network. This study provides valuable insights into the molecular mechanisms underlying UM and highlights the potential of targeting the ZNF197-AS1/miR-425/GABARAPL1 axis as a therapeutic strategy for UM.NEW & NOTEWORTHY This study identifies the ZNF197-AS1/miR-425/GABARAPL1 axis as a novel regulatory mechanism in uveal melanoma. ZNF197-AS1 upregulates GABARAPL1 by sponging miR-425, inhibiting UM cell proliferation, migration, and invasion. This discovery highlights a potential therapeutic target, providing new insights into UM progression and patient outcomes.

Slow proliferation of BAP1-deficient uveal melanoma cells is associated with reduced S6 signaling and resistance to nutrient stress

Uveal melanoma (UM) is the deadliest form of eye cancer in adults. Inactivating mutations and/or loss of expression of the gene encoding BRCA1-associated protein 1 (BAP1) in UM tumors are associated with an increased risk of metastasis. To investigate the mechanisms underlying this risk, we explored the functional consequences of BAP1 deficiency. UM cell lines expressing mutant BAP1 grew more slowly than those expressing wild-type BAP1 in culture and in vivo. The ability of BAP1 reconstitution to restore cell proliferation in BAP1-deficient cells required its deubiquitylase activity. Proteomic analysis showed that BAP1-deficient cells had decreased phosphorylation of ribosomal S6 and its upstream regulator, p70S6K1, compared with both wild-type and BAP1 reconstituted cells. In turn, expression of p70S6K1 increased S6 phosphorylation and proliferation of BAP1-deficient UM cells. Consistent with these findings, BAP1 mutant primary UM tumors expressed lower amounts of p70S6K1 target genes, and S6 phosphorylation was decreased in BAP1 mutant patient-derived xenografts (PDXs), which grew more slowly than wild-type PDXs in the liver (the main metastatic site of UM) in mice. BAP1-deficient UM cells were also more resistant to amino acid starvation, which was associated with diminished phosphorylation of S6. These studies demonstrate that BAP1 deficiency slows the proliferation of UM cells through regulation of S6 phosphorylation. These characteristics may be associated with metastasis by ensuring survival during amino acid starvation.

Immunohistochemical staining techniques of intraocular tumors

The peroxidase-antiperoxidase staining technique for the antigens S-100, neuron-specific enolase, and alpha 1-antichymotrypsin (alpha 1ACT) was applied to 57 intraocular tumors: 46 malignant melanomas of the uvea, seven retinoblastomas, and four tumors metastasizing to the eye. The staining characteristics of the different intraocular tumors were compared. Staining for S-100 in a fine-needle aspiration biopsy sample taken from a malignant melanoma of the choroid before enucleation of the globe was attempted. The positive staining of a few cells thus obtained suggested that this technique may be helpful in the diagnosis of melanomas. The alpha 1ACT stain used in this study has not been used previously in ophthalmology to our knowledge. We found 60% of malignant melanomas of the choroid stained positively. Another finding was the staining of the retinal pigment epithelium with alpha 1ACT in 30% of eyes with malignant melanoma of the uvea.

Prediction of metastasis of uveal melanoma: comparison of morphometric determination of nucleolar size and spectrophotometric determination of DNA

We studied 95 cases of uveal melanoma using cytomorphometry to measure the standard deviation of nucleolar area (SD-NA) based on 200 cells per tumor and microspectrophotometry to determine the quantity of DNA in the nucleus of 100 cells per tumor. The 95 cases of uveal melanoma, in which the eye was enucleated between 1970 and 1973, were selected from the files of the REgistry of Ophthalmic Pathology. Forty-nine patients survived with a median follow-up of 15 years without evidence of metastasis at the time of the last follow-up, and 46 patients died of metastatic melanoma. Statistical analysis indicated that SD-NA was a better predictor of metastasis than DNA determination in this data set.

Effect of melanocyte stimulating hormone on human cultured choroidal melanocytes, uveal melanoma cells, and retinal epithelial cells

PURPOSE

To establish methodology for the culture of human choroidal melanocytes to compare their responsiveness to melanocyte stimulating hormone (MSH) with that of their transformed melanoma counterparts and with that of the retinal epithelial cell.

METHODS

Choroidal melanocytes from the choroid of eyes enucleated for the presence of malignant melanoma were cultured in MCDB 153 medium supplemented with insulin, transferrin, hydrocortisone, glutamine, nystatin, vitamin E, phorbol myristate acetate, bovine hypothalamic extract, cholera toxin, and chelexed fetal calf serum.

RESULTS

High yields of pure spindle-shaped bipolar melanocytes were obtained with a doubling time of 3 to 4 days in nine consecutive eyes. Cells continued to divide after 4 months in culture. In contrast, uveal malignant melanoma cells grew rapidly in a relatively simple medium of Ham's F12:DMEM (1:1) supplemented with fetal calf serum, insulin, transferrin and glutamine. This medium was unable to support choroidal melanocytes. Choroidal melanocytes were DOPA-positive with appreciable tyrosinase activity that significantly increased with treatment with MSH. MSH also significantly altered the size, local density, and distribution of primary and mature melanosomes of ocular melanocytes. In contrast, uveal melanoma cells had a low level of tyrosinase activity and failed to respond to MSH with either an increase in enzyme activity or melanosome size. Retinal epithelial cells failed to show significant tyrosinase activity under the conditions studied or any increase in melanosome size in response to MSH.

CONCLUSION

Ocular melanocytes show evidence of regulation by MSH and a range of mitogenic stimuli unlike the transformed melanoma cells, implying a loss of regulatory control in the latter.

CYSLTR1 antagonism displays potent anti-tumor effects in uveal melanoma

Uveal Melanoma (UM) is the most common primary intraocular malignancy in adults. Although rare, it is a deadly tumor, with a long-term prognosis of death occurring in more than 50% of the cases. It is characterized by frequent (∼80%) driver mutations in GNAQ and GNA11 genes, both of which are activated by cysteinyl leukotriene receptors (CYSLTRs). CYSLTR1 is upregulated and participated in the progression of several cancers. In the present study, we sought to determine the expression levels of CYSLTR1 in 31 human UM specimens and cell lines (3 primary and 1 metastatic), and its role in the proliferation and viability of these cells by analyzing cell metabolic activity, cell confluence and apoptosis levels. We show that all analyzed UM specimens and cells expressed CYSLTR1 at high levels. Notably, the pharmacological blockage of this receptor, using the inverse agonist MK571, reduced the growth and metabolic activity, and increased the apoptotic cell death of all analyzed UM cell lines. We provide evidence that CYSLTR1 is expressed in human UM and plays a significant role in UM progression behavior. Our data highlight the potential beneficial effects of targeting CYSLTR1 in the control of UM progression.

Modulating DNA damage response in uveal melanoma through embryonic stem cell microenvironment

BACKGROUND

Uveal melanoma (UVM) is the most common primary intraocular tumor in adults, with a median survival of 4-5 months following metastasis. DNA damage response (DDR) upregulation in UVM, which could be linked to its frequent activation of the PI3K/AKT pathway, contributes to its treatment resistance. We have reported that embryonic stem cell microenvironments (ESCMe) can revert cancer cells to less aggressive states through downregulation of the PI3K signaling, showing promise in modulating the DDR of UVM.

METHODS

Since nonhomologous end joining (NHEJ) is the main DNA repair mechanism in UVM, this study utilized gene expression analysis and survival prognosis analysis to investigate the role of NHEJ-related genes in UVM based on public databases. Xenograft mouse models were established to assess the therapeutic potential of ESC transplantation and exposure to ESC-conditioned medium (ESC-CM) on key DNA repair pathways in UVM. Quantitative PCR and immunohistochemistry were used to analyze NHEJ pathway-related gene expression in UVM and surrounding normal tissues. Apoptosis in UVM tissues was evaluated using the TUNEL assay.

RESULTS

PRKDC, KU70, XRCC5, LIG4 and PARP1 showed significant correlations with UM progression. High expression of PRKDC and XRCC5 predicted poorer overall survival, while low PARP1 and XRCC6 expression predicted better disease-free survival in UVM patients. ESCMe treatment significantly inhibited the NHEJ pathway transcriptionally and translationally and promoted apoptosis in tumor tissues in mice bearing UVM. Furthermore, ESC transplantation enhanced DDR activities in surrounding normal cells, potentially mitigating the side effects of cancer therapy. Notably, direct cell-to-cell contact with ESCs was more effective than their secreted factors in regulating the NHEJ pathway.

CONCLUSIONS

Our results suggest that NHEJ-related genes might serve as prognostic markers and therapeutic targets in UVM. These findings support the therapeutic potential of ESC-based therapy in enhancing UVM sensitivity to radiochemotherapy and improving treatment outcomes while minimizing damage to healthy cells.

Systematic drug screening and target analysis identify digitoxin as a potential therapy for uveal melanoma

BACKGROUND AND PURPOSE

Cardiac glycosides (CGs), traditionally prescribed for heart failure and arrhythmias, show anticancer potential. However, their mechanisms for preferential inhibition of tumour tissue and constituent malignant cells are not fully elucidated. This study aims to elucidate the therapeutic benefits of CGs in targeting specific tumours and dissect their multi-targeting mechanisms that confer their cytotoxicity against malignant cells.

EXPERIMENTAL APPROACH

We designed an integrated workflow to identify therapeutic CGs with high toxicity to certain cancers, investigating their multi-target effects, assessing their toxicity to malignant cells and analysing the prognostic relevance of CGs' target genes. The computational findings were confirmed through gene knockdown, cell viability assays, reactive oxygen species (ROS) measurements and so forth.

KEY RESULTS

CGs modulate multiple genes crucial for ion homeostasis, oxidative stress and apoptosis, with a particularly strong inhibitory effects on uveal melanoma (UVM). Notably, digitoxin suppresses UVM cell proliferation and induces ROS levels by simultaneously targeting STAT3 and KLF5. Single-cell transcriptomic analysis revealed that malignant cells are likely more vulnerable to CGs due to their higher expression of CG target genes compared with surrounding cells in the UVM microenvironment.

CONCLUSIONS AND IMPLICATIONS

Given UVM's limited options, our study highlights the potential of digitoxin as a promising novel therapeutic agent for this aggressive and rare ocular cancer. Our comprehensive approach is effective in identifying the potent, cancer-specific therapeutic agents from herbal plants.

18F-FDG PET/CT assessment of metabolic tumor burden predicts survival in patients with metastatic posterior uveal melanoma

The prognostic value of metabolic tumor burden parameters obtained from 18F-FDG PET/CT imaging was evaluated in this retrospective national multicenter study of patients with metastatic posterior uveal melanoma (PUM) and compared to the largest diameter of the largest metastatic lesion (LDLM) and the American Joint Committee on Cancer (AJCC) staging system. The Maximal Standard Uptake Value (SUVmax), Metabolic Tumor Volume (MTV), and Total Lesion Glycolysis (TLG) were obtained in 106 patients. Higher values of SUVmax (p = 0.007, log-rank), MTV (p < 0.001, log-rank), and TLG (p < 0.001, long-rank) were associated with shorter survival. The three parameters were also independent predictors in the multivariate Cox model, while the AJCC staging turned insignificant. Time-dependent positive predictive value (PPV) analysis and Receiver Operating Characteristics (ROC) curves showed that MTV (Area Under the Curve (AUC) = 0.78), TLG (AUC = 0.78), and LDLM (AUC = 0.76) were good predictors of 1-year survival. For the subset of 97 patients with liver metastases, the corresponding regional measurements in the liver tended to be even better predictors. In conclusion, MTV and TLG were found to be better predictors of survival in metastatic PUM than the AJCC staging system, but when LDLM was used as a continuous variable it showed an equally good prediction of 1-year survival.

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.