Primary Uveal Melanoma Samples Research Articles

Novel prognostication biomarker adipophilin reveals a metabolic shift in uveal melanoma and new therapeutic opportunities.

Metastatic uveal melanoma remains incurable at present. We previously demonstrated that loss of BAP1 gene expression in tumour cells triggers molecular mechanisms of immunosuppression in the tumour microenvironment (TME) of metastatic uveal melanoma. Adipophilin is a structural protein of lipid droplets involved in fat storage within mammalian cells, and its expression has been identified in uveal melanoma. We comprehensively evaluated adipophilin expression at the RNA (PLIN2) and protein levels of 80 patients of the GDC-TCGA-UM study and in a local cohort of 43 primary uveal melanoma samples respectively. PLIN2 expression is a survival prognosticator biomarker in uveal melanoma. Loss of adipophilin expression is significantly associated with monosomy 3 status and nuclear BAP1 losses in uveal melanoma tumours. Integrative transcriptomic and secretome studies show a relationship between transient loss of adipophilin expression and increased levels of tumour-associated macrophages and hypoxia genes, suggesting PLIN2-dependent changes in oxygen and lipid metabolism in the TME of low and high-metastatic risk uveal melanoma. We designed four adipophilin-based multigene signatures for uveal melanoma prognostication using a transcriptomic and secretome survival-functional network approach. Adipophilin-based multigene signatures were validated in BAP1-positive and BAP1-negative uveal melanoma cell lines using a next-generation RNA sequencing approach. We identified existing small molecules, mostly adrenergic, retinoid, and glucocorticoid receptor agonists, MEK, and RAF inhibitors, with the potential to reverse this multigene signature expression in uveal melanoma. Some of these molecules were able to impact tumour cell viability, and carvedilol, an adrenergic receptor antagonist, restored PLIN2 levels, mimicking the expression of normoxia/lipid storage signatures and reversing the expression of hypoxia/lipolysis signatures in co-cultures of uveal melanoma cells with human macrophages. These findings open up a new research line for understanding the lipid metabolic regulation of immune responses, with implications for therapeutic innovation in uveal melanoma. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

1,4-dihydroxy quininib modulates the secretome of uveal melanoma tumour explants and a marker of oxidative phosphorylation in a metastatic xenograft model.

Uveal melanoma (UM) is an intraocular cancer with propensity for liver metastases. The median overall survival (OS) for metastatic UM (MUM) is 1.07 years, with a reported range of 0.84-1.34. In primary UM, high cysteinyl leukotriene receptor 1 (CysLT1) expression associates with poor outcomes. CysLT1 antagonists, quininib and 1,4-dihydroxy quininib, alter cancer hallmarks of primary and metastatic UM cell lines in vitro. Here, the clinical relevance of CysLT receptors and therapeutic potential of quininib analogs is elaborated in UM using preclinical in vivo orthotopic xenograft models and ex vivo patient samples. Immunohistochemical staining of an independent cohort (n = 64) of primary UM patients confirmed high CysLT1 expression significantly associates with death from metastatic disease (p = 0.02; HR 2.28; 95% CI 1.08-4.78), solidifying the disease relevance of CysLT1 in UM. In primary UM samples (n = 11) cultured as ex vivo explants, 1,4-dihydroxy quininib significantly alters the secretion of IL-13, IL-2, and TNF-α. In an orthotopic, cell line-derived xenograft model of MUM, 1,4-dihydroxy quininib administered intraperitoneally at 25 mg/kg significantly decreases ATP5B expression (p = 0.03), a marker of oxidative phosphorylation. In UM, high ATP5F1B is a poor prognostic indicator, whereas low ATP5F1B, in combination with disomy 3, correlates with an absence of metastatic disease in the TCGA-UM dataset. These preclinical data highlight the diagnostic potential of CysLT1 and ATP5F1B in UM, and the therapeutic potential of 1,4-dihydroxy quininib with ATP5F1B as a companion diagnostic to treat MUM.

Characterization of Uveal Melanoma Cell Lines and Primary Tumor Samples in 3D Culture.

PurposeUveal melanoma (UM) typically spreads to the liver, where it is incurable, as there are limited therapeutic interventions available. This study aimed to standardize laboratory methods for generating three-dimensional (3D) spheroids using UM cell lines and primary UM (PUM) samples for use in drug screening.MethodsSix UM cell lines and nine PUM, of differing genetic characteristics were cultured in two dimensions (2D) and three dimensions. 3D spheroid formation and growth were time monitored, and ImageJ software was used to calculate cross-sectional areas. PUM spheroids underwent immunohistochemistry for melanoma markers, nuclear BAP1, and cell proliferation. Chromosomal alterations in patient UM biopsies were compared with the corresponding 3D spheroid. In vitro drug assays testing doxorubicin and selumetinib assessed drug penetration and toxicity after 48 hours using imaging and the CellTiter-Glo 3D Cell Viability Assay.ResultsAll six UM cell lines formed spheroids of varying sizes and compactness; six of the nine PUM samples (67%) also formed spheroids, composed of MelanA+ proliferating melanocytes and admixed macrophages. PUM spheroids were genetically identical to the original sampled tumor. In vitro drug assays showed varying penetrations into UM cell line spheroids, with doxorubicin passing into the spheroid core and selumetinib having an effect largely on peripheral cells. Both drugs caused a dose-dependent reduction in viability of 3D spheroid cells.ConclusionsUM cell lines and PUM samples can successfully generate uniform 3D spheroids. PUM spheroids retain histological and genetic characteristics of the primary tumor. 3D spheroids are an important system for use in future high-throughput drug testing.Translational RelevanceThe use of 3D spheroids allows early-phase drug screening and is an important first step toward treatment personalization for UM patients.

Nestin expression in primary and metastatic uveal melanoma - possible biomarker for high-risk uveal melanoma.

Nestin, a member of the intermediate filament protein family, has been described as a putative cancer stem cell marker (CSC) in uveal melanoma and poor prognostic factor in a variety of tumours, including cutaneous melanoma. In this study, we examined the expression of nestin in primary (PUM) and metastatic uveal melanoma (MUM) samples, and correlated the findings with histological, clinical and survival data. Nestin expression was assessed by immunohistochemistry in 141 PUM and 26 MUM samples; 11 PUM cases were matched with their corresponding metastases. The percentage of tumour cells expressing nestin was scored by three independent observers. Statistical analysis of all data was performed with SPSS. Nestin expression was identified in both the cytoplasm and membrane of UM cells. Increased expression of nestin in PUM samples was associated with known poor prognostic parameters, including epithelioid cell morphology (p<0.001), closed loops (p=0.001), higher mitotic count (p<0.001), monosomy 3 (p=0.007) and chromosome 8q gain (p<0.001). Primary uveal melanoma (PUM) with nestin expression levels above a cut-off value of 10% [as determined by receiver operating characteristic (ROC) analysis] was associated with a significantly reduced survival time (Log-rank, p=0.002). In MUM, a higher percentage of nestin-positive tumour cells combined with poor prognostic markers in the PUM led to a shorter survival time following the development of metastases. In conclusion, increased nestin expression in PUM is a predictor of a tumour phenotype associated with metastatic progression and reduced survival time at onset of metastasis.

The DecisionDx-UM Gene Expression Profile Test Provides Risk Stratification and Individualized Patient Care in Uveal Melanoma.

Uveal melanoma (UM) is the most common primary cancer of the eye and has a strong propensity for metastasis. Although there have been many recent improvements in the diagnosis and treatment of UM, and only 2-4% of patients present with detectable metastasis, up to half of patients are at risk for dying of metastatic disease. Clinicopathologic factors are not accurate enough for individualized patient care. Chromosomal alterations have been used for prognostic purposes, but the routine clinical use of these methods is limited by their susceptibility to sampling error resulting from tumor heterogeneity, limited clinical validation, lack of standardized testing platforms, and high technical failure rates. In contrast, the DecisionDx-UM gene expression profile test is a stand-alone platform which requires no other information for maximal prognostic accuracy and which circumvents many of the drawbacks of chromosomal methods through the use of a highly sensitive microfluidics, PCR-based platform that simultaneously measures the expression of 15 carefully selected genes from primary uveal melanoma samples obtained by fine needle biopsy. Low metastatic risk is reported as Class 1, and high metastatic risk as Class 2. The test allows patients to be stratified into risk categories such that high-risk patients can be offered intensive metastatic surveillance and adjuvant therapy while low-risk patients can be spared these interventions. This test is now used as part of the standard of care in many ocular oncology centers.

Notch Signaling Promotes Growth and Invasion in Uveal Melanoma

To determine whether uveal melanoma, the most common primary intraocular malignancy in adults, requires Notch activity for growth and metastasis. Expression of Notch pathway members was characterized in primary tumor samples and in cell lines, along with the effects of Notch inhibition or activation on tumor growth and invasion. Notch receptors, ligands, and targets were expressed in all five cell lines examined and in 30 primary uveal melanoma samples. Interestingly, the three lines with high levels of baseline pathway activity (OCM1, OCM3, and OCM8) had their growth reduced by pharmacologic Notch blockade using the γ-secretase inhibitor (GSI) MRK003. In contrast, two uveal melanoma lines (Mel285 and Mel290) with very low expression of Notch targets were insensitive to the GSI. Constitutively active forms of Notch1 and Notch2 promoted growth of uveal melanoma cultures and were able to rescue the inhibitory effects of GSI. MRK003 treatment also inhibited anchorage-independent clonogenic growth and cell invasion and reduced phosphorylation levels of STAT3 and extracellular signal-regulated kinase (Erk)1/2. Suppression of canonical Notch activity using short hairpin RNA targeting Notch2 or CBF1 was also able to reduce tumor growth and invasion. Finally, intraocular xenograft growth was significantly decreased by GSI treatment. Our findings suggest that Notch plays an important role in inducing proliferation and invasion in uveal melanoma and that inhibiting this pathway may be effective in preventing tumor growth and metastasis.

Lack of OncogenicGNAQMutations in Melanocytic Lesions of the Conjunctiva as Compared to Uveal Melanoma

Somatic mutations in codon 209 of the GNAQ gene are the first initiating events to be identified in uveal melanoma. The purpose of this study was to search for GNAQ209 mutations in conjunctival melanocytic lesions. Forty archival samples of conjunctival melanocytic lesions (conjunctival nevi, primary acquired melanosis, and conjunctival melanoma), 27 samples of uveal melanoma, and 11 samples of uveal melanoma metastases to the liver (3 of which matched primary uveal melanoma samples)-a total of 78 samples from 75 patients- were examined for the presence of GNAQ209 mutations by using chip-based, matrix-assisted laser-desorption time-of-flight (MALDI-TOF) mass spectrometry. Direct sequencing was also performed. The GNAQ209 mutation was identified in 12 (44.5%) uveal melanoma samples and 4 (36.5%) of the 11 metastases of uveal melanoma. It was not detected in any of the other melanocytic lesions. The GNAQ209 mutation rate in uveal melanoma in this study is in line with the rate in other reports. The finding of the same genotype in the primary tumors and their metastases suggests that mutation in GNAQ is an early event in uveal melanoma tumorigenesis. The lack of GNAQ mutations in conjunctival melanocytic lesions suggests the involvement of a different tumorigenic pathway from that of uveal melanoma.

Epigenetic Regulation IdentifiesRASEFas a Tumor-Suppressor Gene in Uveal Melanoma

Recently, a segregation study in families with uveal and cutaneous melanoma identified 9q21 as a potential locus harboring a tumor-suppressor gene (TSG). One of the genes in this area, RASEF, was then analyzed as a candidate TSG, but lack of point mutations and copy number changes could not confirm this. In this study, the RASEF gene was investigated for potential mutations and gene silencing by promoter methylation in uveal melanoma. Eleven uveal melanoma cell lines and 35 primary uveal melanoma samples were screened for mutations in the RASEF gene by high-resolution melting-curve and digestion analysis. Expression of RASEF was determined by real-time RT-PCR in all cell lines and 16 primary uveal melanoma samples, and the methylation status of the promoter of the RASEF gene was analyzed and confirmed by direct sequencing. Mutation screening revealed a known polymorphism (R262C; C-->T) in exon 5 of the RASEF gene that displayed a normal frequency (54%). Of the primary uveal melanomas, 46% presented a heterozygous genotype, and 10 (91%) of 11 cell lines showed a homozygous genotype. Melting-curve analysis indicated loss of heterozygosity in at least two primary tumors. Low RASEF expression in the cell lines and primary tumors correlated with methylation of the RASEF promoter region. Homozygosity and methylation of the RASEF gene in primary tumors were associated with decreased survival (P = 0.019). Homozygosity, in combination with methylation, appears to be the mechanism targeting RASEF in uveal melanoma, and allelic imbalance at this locus supports a TSG role for RASEF.

Increased chondroitin sulphate proteoglycan expression (B5 immunoreactivity) in metastases of uveal melanoma

BackgroundMetastatic uveal melanoma has a poor prognosis and limited therapeutic options. Proteoglycans are involved in tumor cell invasion and metastatic behavior. The mAbB5 stains a chondroitin sulphate proteoglycan (CSPG) on cutaneous melanoma cells. Here, we compare the B5-staining of CSPG in primaries and metastases of uveal melanoma. Material and methodsImmunohistopathological staining was performed in 15 cutaneous and 39 uveal melanoma samples. A score for intracellular and surface staining was established. B5 staining was compared in primaries and metastases of uveal melanoma using Student's t-test. ResultsEight of 11 (73%) uveal melanoma metastases were positive for B5-staining whereas only 5 of 28 (18%) primary uveal melanoma samples were B5-positive (P < 0.001). Nine of 15 cutaneous melanoma samples (60%) were B5-positive without significant difference between primary and metastatic lesions. Surface staining was found both on uveal melanoma metastases and cutaneous melanomas. ConclusionsCSPG was expressed significantly more often in metastases than in primaries of uveal melanoma. It potentially may be one factor associated with metastatic spread. Further studies are needed to determine its use as prognostic factor. The mAbB5 may also be a promising tool for immunotherapy due to its strong staining of CSPG on the surface of cutaneous and metastatic uveal melanoma cells.

The RAS-BRAF kinase pathway is not involved in uveal melanoma.

An activating mutation has been recently observed in cutaneous melanoma in a downstream component of RAS-BRAF. The most common mutation, occurring in 80% of cutaneous melanoma samples, is a T-to-A transition resulting in a single amino acid substitution (V599E). Since cutaneous and uveal melanoma (UM) have a common origin, we aimed to establish whether activation of the BRAF proto-oncogene is also an important factor in the development of UM. Exons 11 through 18 of the BRAF gene were screened from 33 primary UMs and 11 UM cell lines. Genomic polymerase chain reaction products were evaluated using single-strand conformation polymorphism analysis, followed by sequencing of aberrant products. The most common mutation, T1796A in the kinase domain of BRAF, was not observed in any of the primary UM samples. This mutation was also absent in 10 of the 11 UM cell lines. In one of the UM cell lines, OCM1, the T1796A mutation was present. We conclude that, in contrast to cutaneous melanoma, BRAF does not appear to be involved in the pathogenesis of UM.