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.

Epidemiological and histopathological aspects of ocular melanomas in Northeastern Romania.

Ocular melanoma is a rare but complex disease in current medical practice. Our retrospective study spans over a period of 28 years and analyzed uveal and conjunctival melanomas that were consecutively admitted, diagnosed, and treated in the 2nd Ophthalmology Clinic of Prof. Dr. Nicolae Oblu Emergency Clinical Hospital, Iasi, Romania. The patients were selected from the records of the Department of Pathology of our Hospital, being diagnosed by standard histopathological techniques. The aim of this study was to summarize the epidemiological and pathological aspects of uveal and conjunctival melanomas in Northeastern region of Romania. In our study, we did not notice a predilection of uveal and conjunctival melanoma to one particular gender. The most common histological subtypes of ocular melanomas were the heavily pigmented spindle cell subtype, followed by the epithelioid subtype. Our patients sought medical help in a timely manner, before the systemic invasion of the disease could develop.

The multiple roles of autophagy in uveal melanoma and the microenvironment.

PURPOSE: Uveal melanoma (UM) is the most common primary malignant intraocular tumor in adults, and effective clinical treatment strategies are still lacking. Autophagy is a lysosome-dependent degradation system that can encapsulate abnormal proteins, damaged organelles. However, dysfunctional autophagy has multiple types and plays a complex role in tumorigenicity depending on many factors, such as tumor stage, microenvironment, signaling pathway activation, and application of autophagic drugs. METHODS: A systematic review of the literature was conducted to analyze the role of autophagy in UM, as well as describing the development of autophagic drugs and the link between autophagy and the tumor microenvironment. RESULTS: In this review, we summarize current research advances regarding the types of autophagy, the mechanisms of autophagy, the application of autophagy inhibitors or agonists, autophagy and the tumor microenvironment. Finally, we also discuss the relationship between autophagy and UM. CONCLUSION: Understanding the molecular mechanisms of how autophagy differentially affects tumor progression may help to design better therapeutic regimens to prevent and treat UM.

What matters most to people with metastatic uveal melanoma? A qualitative study to inform future measurement of health-related quality of life.

Metastatic uveal melanoma (mUM) is a rare cancer with poor prognosis, but novel treatments are emerging. Currently, there are no mUM-specific health-related quality of life (HRQL) questionnaires available for clinical research. We aimed to explore how mUM and its treatment affect HRQL and assess the content validity of existing questionnaires. Participants were patients with mUM and healthcare professionals involved in their care. Qualitative data were collected using semi-structured interviews and focus groups. Data collection and analysis used an integrative approach involving inductive questions/coding to elicit new concepts and deductive questions/coding based on domains of existing HRQL questionnaires. Initial interviews/focus groups focussed on HRQL questionnaires designed for patients with uveal melanoma or liver metastases. As new concepts were elicited, domains and items from other questionnaires were subsequently added. Seventeen patients and 16 clinicians participated. HRQL concerns assessed by uveal melanoma-specific questionnaires were largely resolved by the time of metastasis. The Functional Assessment of Cancer Therapy - Immunotherapy Module (FACT-ICM) adequately captured most immunotherapy-related side effects during initial treatment cycles. However, most patients emphasised emotional impacts over physical ones, focussing on the existential threat posed by disease amidst uncertainty about treatment accessibility and effectiveness. Patients were also concerned with treatment burden, including time commitment, travel, need for hospitalisation, and expenses. The relative importance of HRQL issues varied over time and across treatment modalities, with no single questionnaire being sufficient. Pending further development and psychometric testing, clinical researchers may need to take a modular approach to measuring the HRQL impacts of mUM.

Machine Learning Methods for Gene Selection in Uveal Melanoma.

Uveal melanoma (UM) is the most common primary intraocular malignancy with a limited five-year survival for metastatic patients. Limited therapeutic treatments are currently available for metastatic disease, even if the genomics of this tumor has been deeply studied using next-generation sequencing (NGS) and functional experiments. The profound knowledge of the molecular features that characterize this tumor has not led to the development of efficacious therapies, and the survival of metastatic patients has not changed for decades. Several bioinformatics methods have been applied to mine NGS tumor data in order to unveil tumor biology and detect possible molecular targets for new therapies. Each application can be single domain based while others are more focused on data integration from multiple genomics domains (as gene expression and methylation data). Examples of single domain approaches include differentially expressed gene (DEG) analysis on gene expression data with statistical methods such as SAM (significance analysis of microarray) or gene prioritization with complex algorithms such as deep learning. Data fusion or integration methods merge multiple domains of information to define new clusters of patients or to detect relevant genes, according to multiple NGS data. In this work, we compare different strategies to detect relevant genes for metastatic disease prediction in the TCGA uveal melanoma (UVM) dataset. Detected targets are validated with multi-gene score analysis on a larger UM microarray dataset.

Mass Spectrometry-Based Profiling of Histone Post-Translational Modifications in Uveal Melanoma Tissues, Human Melanocytes, and Uveal Melanoma Cell Lines - A Pilot Study.

Purpose: Epigenetic alterations in uveal melanoma (UM) are still neither well characterized, nor understood. In this pilot study, we sought to provide a deeper insight into the possible role of epigenetic alterations in the pathogenesis of UM and their potential prognostic relevance. To this aim, we comprehensively profiled histone post-translational modifications (PTMs), which represent epigenetic features regulating chromatin accessibility and gene transcription, in UM formalin-fixed paraffin-embedded (FFPE) tissues, control tissues, UM cell lines, and healthy melanocytes. Methods: FFPE tissues of UM (n = 24), normal choroid (n = 4), human UM cell lines (n = 7), skin melanocytes (n = 6), and uveal melanocytes (n = 2) were analyzed through a quantitative liquid chromatography-mass spectrometry (LC-MS) approach. Results: Hierarchical clustering showed a clear separation with several histone PTMs that changed significantly in a tumor compared to normal samples, in both tissues and cell lines. In addition, several acetylations and H4K20me1 showed lower levels in BAP1 mutant tumors. Some of these changes were also observed when we compared GNA11 mutant tumors with GNAQ tumors. The epigenetic profiling of cell lines revealed that the UM cell lines MP65 and UPMM1 have a histone PTM pattern closer to the primary tissues than the other cell lines analyzed. Conclusions: Our results suggest the existence of different histone PTM patterns that may be important for diagnosis and prognosis in UM. However, further analyses are needed to confirm these findings in a larger cohort. The epigenetic characterization of a panel of UM cell lines suggested which cellular models are more suitable for epigenetic investigations.

New immunotherapy approaches as the most effective treatment for uveal melanoma.

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Conventional methods of UM treatment are based on chemotherapy and radiotherapy, which have been able to control tumor growth in a limited way. But due to the inadequacy and many side effects of these treatments, many UM patients die during treatment, and approximately 50% of patients develop metastasis. Meanwhile, the 2-year survival rate of these patients from the time of metastasis is 8%. Since immunotherapy has the potential to be the most specific and efficient method in the treatment of tumors, it is considered an attractive and promising research field in the treatment of UM. This review highlights recent advances in UM immunotherapy and provides new immunological approaches on how to overcome the challenges of UM immunotherapy.

Prognostic Value of BAP1 Protein Expression in Uveal Melanoma.

The prognostic value of the traditional pathologic parameters that form part of the American Joint Committee on Cancer staging system and genetic classifications using monosomy chromosome 3 and structural alterations in chromosome 8 are well established and are part of the diagnostic workup of uveal melanoma (UM). However, it has not been fully clarified whether nuclear protein expression of the tumor suppressor gene BAP1 (nBAP1) by immunohistochemistry alone is as powerful a predictor of overall survival (OS) and/or disease-specific survival (DSS) as chromosome analysis. The protein expression of nBAP1 was evaluated in a retrospective cohort study of 308 consecutive patients treated by primary enucleation between January 1974 and December 2022. We correlated clinical, pathologic, and cytogenetic characteristics to identify the best prognostic indicators for OS and DSS. Loss of nBAP1 was detected in 144/308 (47%) of patients. Loss of nBAP1 expression was significantly associated with poor survival. In patients with disomy chromosome 3, nBAP1 negative is significantly associated with poorer OS but not DSS. We observed that older age (>63 years), presence of metastasis, and nBAP1 negative remained independent prognostic factors in multivariate analysis. nBAP1 protein expression proved to be a more reliable prognostic indicator for OS than the American Joint Committee on Cancer staging, M3 status, or The Cancer Genome Atlas classification in this cohort. This study provides support for accurate prognostication of UM patients in routine histology laboratories by immunohistochemistry for nBAP1 alone.

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.

The Cancer Genome Atlas for uveal melanoma is predictive of patient outcomes.

Uveal melanoma (UM) is the most common primary eye malignancy. Despite excellent local tumor rates, UM is a life-threatening disease with moderate systemic metastatic rates. In the past, certain clinical features were shown to be predictive of patient prognosis, including tumor thickness, tumor diameter, ciliary body involvement, and histopathologic factors. Genetic markers have lately been used to predict patient outcomes. The Cancer Genome Atlas (TCGA) is a worldwide effort developed by the National Cancer Institute and the National Human Genome Research Institute to study numerous mutations in various cancer types. TCGA has explored chromosome copy number alterations in UM, messenger RNA, micro-RNA, and long noncoding RNA expression levels and established four prognostic classes: group A (chromosome 3 and 8 disomy), group B (chromosome 3 disomy and 8q gain), group C (chromosome 3 monosomy and/or 8q gain), and group D (chromosome 3 monosomy and multiple 8q gains). Multiple studies have validated TCGA classification and have reported that it has been highly predictive of UM metastasis and patient survival.

Importance of multimodal imaging diagnostics in acute angle closure glaucoma: Case report.

To describe the natural history and management of an acute angle closure secondary to choroidal melanoma. A 70-year-old female presented with pain, elevated intraocular pressure, mature cataract, and angle closure in right eye. With further studies she was found to have a choroidal melanoma causing the acute angle closure. Enucleation was performed and the patient is currently in close postoperative surveillance by ophthalmology and oncology. The importance of early identification and treatment of intraocular tumors to decrease incidence of metastasis. In secondary acute angle-closure glaucoma treatment should be targeted towards resolving the triggering factor of glaucoma.

Iris melanoma: Review of clinical features, risks, management, and outcomes.

Primary uveal melanoma is rare and affects approximately 8,000 persons per year worldwide. This malignancy can involve the iris, ciliary body, and choroid. Of these three structures, the iris is the least commonly affected site, representing only 4% of all uveal melanomas. Iris melanoma can arise from iris melanocytic nevus, iris melanocytosis, or de novo. In a longitudinal study of 1,611 patients with iris nevus, transformation into melanoma, using Kaplan-Meier estimates, was found in 2.6% by five years and in 4.1% by 10 years. The factors that predicted growth of iris melanocytic nevus into melanoma are denoted by a letter (ABCDEF) guide: A for age ≤40 years old at presentation (hazard ratio [HR] = 3, P = .01), B for blood (hyphema) (HR = 9, P < .0004), C for clock hour of tumor inferiorly (tumor location) (HR = 9, P = .03), D for diffuse flat tumor configuration (HR = 14, P = .02), E for ectropion uveae (HR = 4, P = .002), and F for feathery ill-defined margins (HR = 3, P = .02). At diagnosis, iris melanoma has a mean cross-sectional diameter of 5.5 mm and thickness of 2.1 mm, often with tumor seeding (28%) and secondary glaucoma (35%). We provide a comprehensive review of iris nevus and melanoma to explore relevant demographic and clinical data, risk factors for tumor growth, management, and prognosis, with the hope that clinicians will be more comfortable in understanding this rare malignant condition.

Association of Fitzpatrick Skin Type with metastatic risk from uveal melanoma in 854 consecutive patients at a single center.

OBJECTIVE: To assess the association of skin color using Fitzpatrick Skin Type (FST) with metastatic risk of uveal melanoma. SUBJECTS: 854 consecutive patients with uveal melanoma and documented FST. METHODS: Retrospective detailed review of patient charts was performed for FST (type I- white, II-fair, III-average, IV-light brown, V-brown, VI-black), clinical details of the patient and the uveal melanoma, tumor cytogenetic classification according to The Cancer Genome Atlas (TCGA), and outcome of melanoma-related metastasis and death. RESULTS: The FST classification was type I (n = 97 patients), type II (n = 665), type III (n = 79), type IV (n = 11), type V (n = 2), type VI (n = 0). A comparison of patient FST (type I vs. II vs. III-V) revealed significant differences in mean age at presentation (64.1 vs. 58.5 vs. 49.8 years, p < 0.001), race white (100% vs. 98% vs. 75%, p < 0.001), presence of ocular melanocytosis (3% vs. 3% vs. 10%, p = 0.01), visual acuity <20/200 at presentation (6% vs. 7% vs. 13%, p = 0.03), genetic results showing TCGA group B tumors (11% vs. 14% vs. 26%, p = 0.01) or TCGA group D tumors (22% vs. 11% vs. 9%, p = 0.01), 10-year incidence of melanoma-related metastasis (25% vs. 15% vs. 14%, p = 0.02) and 10-year incidence of melanoma-related death (9% vs. 3% vs. 4%, p = 0.04). FST was a significant predictor of melanoma-related metastasis (p = 0.02, Hazard ratio 2.3). CONCLUSIONS: Fitzpatrick skin type may be a predictor of melanoma-related metastasis, with metastasis and TCGA Group D tumors being more common in patients with FST I.

B-scan measurements of intraocular tumor heights intraoperatively, before and after radioactive plaque application: A comparative prospective study.

PURPOSE: To assess the difference in intraocular tumors height measurements intraoperatively before and after radioactive plaque application. METHODOLOGY: Twenty-four eyes of 24 patients with intraocular tumors, candidates for radioactive therapy, were included. Each tumor was measured at the same setting before and after plaque application independently by 3 sonographers, using a 20-MHz B-scan transducer. Mean pre-plaque and post-plaque measurements were calculated and recorded. An A-scan vector aided in identification of the inner and outer tumor surfaces. RESULTS: Each patient was examined independently three times by three experienced ultrasonographers within the same setting to assess interobserver variability. There was no statistically significant difference between the 3 examiners' readings, with P-value 0.99 for pre-plaque height and 0.97 for post-plaque height. Mean pre-plaque height was 5.16±2.11mm, while post-plaque height was 5.51±2.1mm (P-value 0.001). The Spearman correlation test showed that initial tumor height was negatively correlated with the difference between both heights, but with no statistical significance. CONCLUSION: Intraocular tumor height measurement differs significantly before and after plaque application. Use of the pre-plaque height is advised until further studies are performed to assess the effect of this difference on treatment outcomes.

Autophagy and vesicular trafficking in human uveal melanoma: A histopathological study.

Uveal melanoma is an ocular tumor with a high risk of developing metastases. The endo-lysosomal system can affect the melanoma progression by accelerating and facilitating invasion or metastasis. This study aims to conduct comparative analysis of normal choroidal melanocytes and uveal melanoma cells ultrastructure with a focus on intracellular transport system, and to examine the patterns of autophagy- and vesicular trafficking-related proteins expression in a case series of uveal melanomas. Transmission electron microscopy was used to assess the ultrastructure of normal choroidal melanocytes and uveal melanoma cells. The expression levels of autophagy- and vesicular trafficking-related proteins in three histological types of uveal melanoma were analyzed by immunofluorescence staining. Electron microscopy results showed that the autophagic vacuoles were more abundant in normal choroidal melanocytes, than in uveal melanoma cells. The normal choroidal melanocytes were characterized by active intracellular vesicular trafficking; however, the proportion of caveolae was higher in uveal melanoma cells. The spindle type of tumor was characterized by a high expression levels of LC3 beta, while Rab7 and Rab11 proteins expression was significantly up-regulated in the mixed-type tumor cells. The results indicate that uveal melanoma cells probably have lower basal levels of autophagy and higher receptor-mediated endocytic trafficking-associated with caveolae than normal choroidal melanocytes. RESEARCH HIGHLIGHTS: The autophagic vacuoles are abundant in normal choroidal melanocytes. Uveal melanoma cells are characterized by a high proportion of caveolae. The high expression levels of LC3 beta were revealed in a spindle type of tumor, while Rab7 and Rab11 proteins expression was up-regulated in the mixed-type tumor cells.

STING promotes invasion and migration of uveal melanoma through p38­MAPK signaling.

Uveal melanoma (UM) is the most common intraocular malignant tumor in adults, with a lack of effective treatment for metastasis and a poor prognosis. Stimulator of interferon genes (STING, also known as TMEM173) plays an important role in tumor development by regulating cell proliferation, metastasis and other cellular processes. However, the function of STING in UM remains unclear and requires further investigation. The present study analyzed the expression status of STING to elucidate the mechanisms underlying UM. The correlation between STING and the prognosis of UM was evaluated based on UM RNA­seq data and clinical information extracted from The Cancer Genome Atlas database. Quantification of STING in UM cell lines and tissues was performed using the Wes Separation protein immunoassay. The effects of STING on the proliferation, migration and invasion of UM cells were investigated using Cell Counting Kit­8, Transwell and wound healing experiments. Survival analysis demonstrated that high levels of STING in UM tissues indicated a poor prognosis. The expression of STING in UM tissues was higher than that in the choroid membranes. Furthermore, it was found that downregulation of STING expression in UM cells suppressed migration and invasion, whereas overexpression of STING significantly promoted migration and invasion. Notably, STING had no significant effect on UM cell proliferation. It was also identified that STING positively upregulated the phosphorylation of p38 mitogen­activated protein kinase (p38­MAPK) in UM cells, enhancing cell migration and invasion, which the p38­MAPK inhibitor SB203580 reversed. Finally, the results of the present study demonstrated that high STING expression in UM indicates a poor prognosis. STING was revealed to promote the migration and invasion of UM cells through p38­MAPK signaling.

Multifocal choroidal melanoma: a clinicohistopathological correlation.

A woman in her late 50s presented with on-and-off redness and diminution of vision in her left eye for 6 months. Her best corrected visual acuity was 20/40 in the right eye and hand motion in the left eye. Anterior segment examination revealed a greyish-white lesion extending from 3 to 6 o'clock hours posterior to the iris and protruding into the anterior chamber. Left eye B-scan ultrasonography showed a multifocal choroidal lesion, a smaller one involving the posterior pole, and a larger lesion involving the complete nasal quadrant and anteriorly extending to the ciliary body and iris. Fine-needle aspiration biopsy performed from the anterior lesion showed a possible neoplastic aetiology of melanocytic origin of the cells. Finally, the patient underwent left eye enucleation with a ball implant. Histopathological examination of the enucleated eye confirmed the final diagnosis of multifocal choroidal melanoma involving the adjacent ciliary body and iris.

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.

Interdependence of Molecular Lesions That Drive Uveal Melanoma Metastasis.

The metastatic risk of uveal melanoma (UM) is defined by a limited number of molecular lesions, somatic mutations (SF3B1 and BAP1), and copy number alterations (CNA): monosomy of chromosome 3 (M3), chr8q gain (8q), chr6p gain (6p), yet the sequence of events is not clear. We analyzed data from three datasets (TCGA-UVM, GSE27831, GSE51880) with information regarding M3, 8q, 6p, SF3B1, and BAP1 status. We confirm that BAP1 mutations are always associated with M3 in high-risk patients. All other features (6p, 8q, M3, SF3B1 mutation) were present independently from each other. Chr8q gain was frequently associated with chr3 disomy. Hierarchical clustering of gene expression data of samples with different binary combinations of aggressivity factors shows that patients with 8q|M3, BAP1|M3 form one cluster enriched in samples that developed metastases. Patients with 6p combined with either 8q or SF3B1 are mainly represented in the other, low-risk cluster. Several gene expression events that show a non-significant association with outcome when considering single features become significant when analyzing combinations of risk features indicating additive action. The independence of risk factors is consistent with a random risk model of UM metastasis without an obligatory sequence.

LKB1-SIK2 loss drives uveal melanoma proliferation and hypersensitivity to SLC8A1 and ROS inhibition.

Metastatic uveal melanomas are highly resistant to all existing treatments. To address this critical issue, we performed a kinome-wide CRISPR-Cas9 knockout screen, which revealed the LKB1-SIK2 module in restraining uveal melanoma tumorigenesis. Functionally, LKB1 loss enhances proliferation and survival through SIK2 inhibition and upregulation of the sodium/calcium (Na+ /Ca2+ ) exchanger SLC8A1. This signaling cascade promotes increased levels of intracellular calcium and mitochondrial reactive oxygen species, two hallmarks of cancer. We further demonstrate that combination of an SLC8A1 inhibitor and a mitochondria-targeted antioxidant promotes enhanced cell death efficacy in LKB1- and SIK2-negative uveal melanoma cells compared to control cells. Our study also identified an LKB1-loss gene signature for the survival prognostic of patients with uveal melanoma that may be also predictive of response to the therapy combination. Our data thus identify not only metabolic vulnerabilities but also new prognostic markers, thereby providing a therapeutic strategy for particular subtypes of metastatic uveal melanoma.