Mutational analysis of selected genes in the TGFbeta,Wnt, pRb,and p53 pathways in primary uveal melanoma

PURPOSE: It is known that the pRb pathway cell-cycle inhibitor p16(INK4A) plays a significant role in cutaneous melanoma and that alteration of p16(INK4A), which resides within the 9p21-22 locus that also contains p15(INK4B) and p14(ARF), may occur in up to one third of uveal melanomas. The absence of TGFbeta responsiveness noted in cultured uveal melanoma cells also suggests that the TGFbeta pathway plays a role in the formation of this tumor. Therefore, mutational screening was performed in several key genes in tumor-suppressor pathways that are known to be altered in some uveal melanomas. METHODS: Using denaturing high-performance liquid chromatography (DHPLC) analysis and DNA sequencing, a series of 67 uveal melanomas were screened for inactivating mutations in the TGFbeta pathway members Smad4 and TGFbeta receptor type 2 (TGFbetaR2), the downstream cell-cycle inhibitor p15(INK4B), and the cell-cycle inhibitors p14(ARF) and p16(INK4A). p16(INK4A) was also investigated for promoter hypermethylation. Mutational analysis was also performed on the Wnt pathway gene beta-catenin, known to be mutated in approximately one quarter of cutaneous melanoma cell lines. RESULTS: Polymorphisms in p16(INK4A) were detected in 3 of 50 samples, but no inactivating mutations were detected in any of the genes screened. Promoter hypermethylation of p16(INK4A) was detected in 5 of 55 tumors, and loss of heterozygosity of the p16(INK4A) locus was detected in 5 of 16 tumors. CONCLUSIONS: Most primary uveal melanomas do not appear to contain somatic mutations in Smad4, TGFbetaR2, p14(ARF), p15(INK4B), p16(INK4A), or beta-catenin. However, methylation of the p16(INK4A) promoter and loss of heterozygosity of the p14(ARF)-p16(INK4A) locus occurs in some tumors.     

Pyrophosphorolysis detects B-RAF mutations in primary uveal melanoma

PURPOSE: Mutations in the genes that control cell proliferation in cutaneous melanoma are generally uncommon in uveal melanoma. Despite the absence of known activating mutations, the RAF-MEK-ERK, or mitogen-activated protein kinase (MAPK), pathway is usually activated in uveal melanoma. An assay with increased potential to identify mutations is now available, and this study was therefore conducted to reanalyze uveal melanoma cell lines and primary tumors for this mutation. METHODS: Eleven uveal melanoma cell lines and 45 primary uveal melanomas were analyzed for mutations in exon 15 of the B-RAF gene by using pyrophosphorolysis-activated polymerization (PAP). Mutations were validated by sequencing of the PAP product. RESULTS: B-RAF mutations were detected in cell lines OCM-1 and -3 (V600E) and in six primary uveal melanomas. The V600K mutation was detected in one primary uveal melanoma, for which the V600E assay turned out to be sensitive as well. Direct sequencing of the exon 15 PCR product did not reveal the mutations found with the PAP-assay, indicating a low frequency of the mutant allele in primary samples. CONCLUSIONS: Because of the very sensitive PAP technology, B-RAF mutations were found in cell lines and primary uveal melanomas, which suggests that they may occasionally play a role in the activation of the MAPK pathway in uveal melanoma and indicates a higher prevalence of B-RAF mutations in uveal melanoma than was reported earlier. However, the relative scarcity of the B-RAF mutation excludes an elemental role for this mutation in uveal melanoma.     

Analysis of p16 (CDKN2/MTS-1/INK4A) alterations in primary sporadic uveal melanoma

PURPOSE: To define more clearly the role of the tumor suppressor gene p16 in uveal melanoma by determining the relative contribution of all known mechanisms of p16 inactivation in this tumor. METHODS: A comprehensive genetic analysis of the p16 gene was performed in 33 primary sporadic ciliochoroidal and choroidal melanomas. Fourteen highly polymorphic microsatellite markers surrounding the p16 locus on chromosome 9p21 were used for the microsatellite analysis. Sequence analysis of the p16 gene was performed on those tumors with 9p21 loss of heterozygosity. To investigate methylation as an alternative mechanism of inactivation of p16, methylation-specific polymerase chain reaction was performed on all tumor DNA samples. RESULTS: Loss of heterozygosity (LOH) was found in 8 of 33 (24%) uveal melanomas. No evidence of a second region of LOH that did not include the p16 locus was found. Four cases had hemizygous losses including markers both distal and proximal to p16. Homozygous deletion of the p16 gene was detected in the 4 remaining cases by microsatellite analysis. Sequence analysis revealed no p16 mutations in the tumors with hemizygous loss of p16. Methylation of the 5' CpG island of p16 was found in one tumor with 9p21 LOH and in another without LOH. CONCLUSIONS: p16 inactivation by HD or methylation occurs in 27% of uveal melanomas, representing the most common molecular genetic alteration identified thus far in uveal melanoma.     

Uveal and cutaneous melanoma: shared expression characteristics of melanoma-associated antigens

PURPOSE: Downregulation of melanoma-associated antigens (MAAs), against which natural cytolytic T lymphocytes (CTLs) exist in humans, is one of the mechanisms that aids in evasion of immune surveillance. In view of putative re-expression strategies for MAAs during immunotherapy, this study was conducted to investigate MAA silencing in malignant melanoma. METHODS: The expression of the MAA Melan-A/MART-1 was analyzed in 10 uveal and 10 cutaneous patient-derived melanoma cell lines by Western blot analysis and RT-PCR. Expression characteristics of four other MAAs-Tyr, Tyrp1, Dct, and gp100/Pmel17-were analyzed by RT-PCR. DNA methylation patterns at the Melan-A/MART-1 promoter region were investigated by methylation-sensitive restriction enzyme digestion and subsequent Southern blot analysis. Exogenous promoter activity was assessed in all 20 melanoma cell lines to correlate the DNA methylation patterns with Melan-A/MART-1 expression. RESULTS: MAA expression was observed in 15 of the 20 melanoma cell lines. Furthermore, there is a direct correlation between DNA methylation patterns at the Melan-A/MART-1 promoter region, exogenous Melan-A/MART-1 promoter activity, and Melan-A/MART-1 protein expression. These data reveal the division of patient-derived melanoma cell lines into two distinct subsets, which are identical for both uveal and cutaneous tumor types. CONCLUSIONS: The authors propose a categorization of melanoma cell lines into two different panels based on shared MAA-expression characteristics: panel I, MAA-expressing cell lines, and panel II, MAA-deficient cell lines. This categorization can be used to obtain knowledge about the regulation of MAA-expression and for further research concerning MAA-based immunotherapy.     

Promoter methylation status of multiple genes in uveal melanoma

PURPOSE: Aberrant promoter hypermethylation of CpG islands is thought to play an important role in the inactivation of tumor-suppressor genes (TSGs) in cancer. Studies of cutaneous melanoma have reported a high methylation rate for MGMT, DAPK, RAR-b2, and RASSF1A. In colon cancer, SOCS-1, IGF-2, RUNX3, NEUROG1, and CACNA1G are commonly inactivated. The concomitant methylation of at least three of these genes may represent a distinct trait, the CpG island methylator phenotype (CIMP). The purpose of the present study was to investigate the role of epigenetic inactivation of multiple genes in uveal melanoma. METHODS: Twenty samples of uveal melanoma were analyzed for the methylation status of nine candidate cancer-related genes: MGMT, DAPK, RAR-b2, RASSF1A, SOCS-1, IGF-2, RUNX3, NEUROG1, and CACNA1G, using real-time quantitative methylation-specific polymerase chain reaction after sodium bisulfite modification. RESULTS: Methylation rates of the genes commonly inactivated in cutaneous melanoma were 70% for RASSFIA, 5% for MGMT and DAPK, and 0 for RAR-b2. The rates for the CIMP-related genes were 25% for RUNX3, 5% for NEUROG1 and CACNA1G, and 0 for SOCS-1 and IGF-2. None of the samples was CIMP-positive. CONCLUSIONS: In this study uveal melanoma was negative for CIMP, with hypermethylation of RASSF1A. The negative CIMP phenotype and frequent RASSF1A methylation in uveal melanoma is in accord with its known lack of BRAF mutations. Given that mutations in genes of the RAS pathway are rarely observed in uveal melanoma, epigenetic inactivation of RASSF1A may be an alternative mechanism of tumorigenesis. The low frequency of promoter methylation of TSGs commonly inactivated in cutaneous melanoma further stratifies the different tumorigenesis pathway in cutaneous and uveal melanoma.     

Functional analysis of the p53 pathway in response to ionizing radiation in uveal melanoma

PURPOSE: Uveal melanomas are notoriously radioresistant and thus necessitate treatment with extremely high radiation doses that often cause ocular complications. The p53 tumor suppressor pathway is a major mediator of the cellular response to radiation-induced DNA damage, suggesting that this pathway may be defective in uveal melanoma. The current study was conducted to analyze the functional integrity of the p53 pathway in primary uveal melanoma cells. METHODS: The p53 gene was sequenced in three primary uveal melanoma cells lines. Cultured primary uveal melanoma cells (MM28, MM50, Mel202, Mel270, and Mel290), MCF7 breast carcinoma cells, normal uveal melanocytes (UM47), and normal human diploid fibroblasts (NHDFs) were irradiated at 250 kVp and 12 mA at a dose rate of 1.08 Gy/min for a total dose of up to 20 Gy. Cell viability was analyzed with trypan blue exclusion. Western blot analysis was used to analyze the expression of p53, p53-phospho-Ser15, p21, Bax, PUMA, and Bcl-x(L). RESULTS: No p53 gene mutations were found in MM28, MM50, or Mel270 cells. Upstream signaling to p53 was intact, with normal induction of p53 and phosphorylation of p53-Ser15, in all five cell lines. Radiation-induced downstream activation of p21 was defective in MM28 and MM50 cells, and activation of Bax was defective in MM50 and Mel290 cells. MM28, MM50, and Mel202 cells failed to deamidate Bcl-x(L) in response to radiation-induced DNA damage. Overall, four of the five uveal melanoma cell lines exhibited at least one downstream defect in the p53 pathway. CONCLUSIONS: Expression of p53 and upstream signaling to p53 in response to radiation-induced DNA damage appear to be intact in most uveal melanomas. In contrast, functional defects in the p53 pathway downstream of p53 activation appear to be common. Further elucidation of p53 pathway abnormalities in uveal melanoma may allow therapeutic interventions to increase the radiosensitivity of the tumors.     

c-Kit-dependent growth of uveal melanoma cells: a potential therapeutic target?

PURPOSE: This study was conducted to investigate the expression and functional impact of the proto-oncogene c-kit in uveal melanoma. METHODS: Based on immunohistochemical (IHC) study of paraffin-embedded specimens from 134 uveal melanomas and Western blot analysis on eight fresh-frozen samples the expression of c-kit in uveal melanoma was studied. Furthermore, the phosphorylation of c-kit and the impact of the tyrosine kinase inhibitor STI571 was examined in the three uveal melanoma cell lines OCM-1, OCM-3, and 92-1. RESULTS: Eighty-four of 134 paraffin-embedded samples and six of eight fresh-frozen samples expressed c-kit. c-Kit was strongly expressed and tyrosine phosphorylated in cultured uveal melanoma cells compared with cutaneous melanoma cells. Moreover, in contrast to cutaneous melanoma cell lines c-kit maintained a high phosphorylation level in serum-depleted uveal melanoma cells. No activation-related mutations in exon 11 of the KIT gene were found. On the contrary, expression of the stem cell growth factor (c-kit ligand) was detected in all three uveal melanoma cell lines, suggesting the presence of autocrine (paracrine) stimulation pathways. Treatment of uveal melanoma cell lines with STI571, which blocks c-kit autophosphorylation, resulted in cell death. The IC(50) of the inhibitory effects on c-kit phosphorylation and cell proliferation was of equal size and less than 2.5 microM. CONCLUSIONS: The results confirm that c-kit is vastly expressed in uveal melanoma, suggest that the c-kit molecular pathway may be important in uveal melanoma growth, and point to its use as a target for therapy with STI571.     

Lack of BRAF mutation in primary uveal melanoma

PURPOSE: BRAF T1796A activating mutations have been found in a high proportion of cutaneous melanomas, cutaneous nevi, and papillary thyroid carcinoma and in a small fraction of other cancers. This study was designed to investigate the incidence of BRAF T1796A mutation in uveal melanoma. METHODS: Twenty-nine formalin-fixed, paraffin-embedded posterior uveal melanomas were included in the study. DNA was extracted from the paraffin sections followed by PCR amplification of exon 15 and detection of the common BRAF missense mutation (T-->A transversion at nucleotide 1796) using restriction enzyme analysis. RESULTS: Although positive cutaneous melanoma control cell lines harbored the T1796A BRAF mutation, none of the 29 uveal melanomas harbored the mutation. CONCLUSIONS: These data suggest that BRAF T1796A activating mutation is not common in primary uveal melanoma. These findings are in accord with known differences in tumorigenesis between uveal and cutaneous melanomas.     

葡萄膜黑色素瘤分子机制及靶向治疗新进展

葡萄膜黑色素瘤是成人眼内最常见的肿瘤。半数以上的原发性葡萄膜黑色素瘤会发生转移。但目前对于转移性葡萄膜黑色素瘤还没有有效的治疗方法。研究葡萄膜黑色素瘤转移、生长、增殖、存活相关的基因突变可以更好地了解其发病机理及转移机制,并基于此开展有效的治疗。本综述对葡萄膜黑色素瘤的分子机制、相应的治疗策略及研究前景进行了总结。     

PD-L1: PD-1 interaction contributes to the functional suppression of T-cell responses to human uveal melanoma cells in vitro

PURPOSE: To assess the expression of PD-L1 on human uveal melanomas and its potential to suppress T-cell function. METHODS: A panel of primary and metastatic uveal melanoma cell lines was evaluated for PD-L1 expression by RT-PCR and flow cytometric analysis. Uveal melanoma-containing eyes were examined for PD-L1 expression by immunohistochemistry. PD-L1 function was tested by coculturing IFN-gamma-pretreated uveal melanoma cells with activated Jurkat T cells for 48 hours and assessing T-cell production of IL-2 by ELISA. RESULTS: Five of the nine primary and one of the five metastatic uveal melanoma cell lines tested constitutively expressed PD-L1 protein at various levels. However, all primary and metastatic uveal melanoma cell lines upregulated PD-L1 expression after stimulation with IFN-gamma. Immunohistochemistry demonstrated that PD-L1 was not expressed by primary uveal melanomas in situ. IL-2 production by activated Jurkat T cells was decreased significantly when the cells were cocultured with IFN-gamma-pretreated uveal melanoma cells. More than 70% of IL-2 production was restored by addition of either anti-PD-L1 or anti-PD-1 antibody to the coculture assays (P < 0.01). CONCLUSIONS: Expression of PD-L1 by uveal melanoma cells regulates T-cell function by suppressing IL-2 production. The results imply that the presence of IFN-gamma in the tumor local microenvironment promotes upregulation of PD-L1 expression by uveal melanoma, which may, in part, promote immune escape by impairing T-cell function. The selective blockade of PD-L1 is a potential strategy in T-cell-based immunotherapy for uveal melanoma.     

Brn-2在人脉络膜黑色素瘤细胞系中的表达及其对MART-1基因启动子活性的影响

目的　探讨黑色素抗原转录子Brn-2在人脉络膜黑色素瘤细胞系中的表达及其对T细胞可识别抗原-1（melanoma antigen recognized by T cells 1,MART-1）启动子活性的影响。方法　采用RT-PCR和Western blot检测人脉络膜黑色素瘤细胞系92-1、92-2、Me1285和Ocm3 细胞中Brn-2的mRNA和蛋白表达水平。将含不同长度MART-1基因启动子序列和荧光素酶报告基因的表达质粒pGL3-Luc构建成融合表达载体pGL3-p286-Luc及pGL3-p2956-Luc,与pEV-Brn-2融合表达质粒共转染脉络膜黑色素瘤细胞系细胞。分别测量四种细胞系中p286组、p2956组、p286+Brn-2组、p2956+Brn-2组细胞荧光素酶表达变化,并观察Brn-2对上述细胞MART-1基因启动子活性的影响。结果　人脉络膜黑色素瘤细胞系92-1、92-2、Me1285、Ocm3细胞系均可检测到Brn-2 mRNA和蛋白的表达,Brn-2蛋白电泳带大致在相对分子质量47 000处。pGL3-p2956-Luc及pGL3-p286-Luc重组质粒经ApaI和NheI双酶切可切出2956 bp和286 bp 2个条带,pEV-Brn-2重组质粒经EcoRI和BamHI双酶切可切出1329 bp条带。pEV-Brn-2重组质粒分别对人脉络膜黑色素瘤细胞系Ocm3、Mel285、92-2、92-1进行磷酸钙法转染,Western blot检测可见四种细胞系均表达Brn-2蛋白。缺乏Brn-2时,所有细胞的MART-1的p286均显示出活性,MART-1阳性细胞系（92-1、92-2、Ocm3）p286活性高于阴性细胞系（Mel285）。p2956活性不同细胞系表现不同,92-1、92-2中较高,Ocm3中其活性与细胞密度相关,MART-1阴性细胞系中p2956近乎无活性。共转染Brn-2后明显下调92-1、92-2、Ocm3中启动子p286及p2956活性（P<0.05）;阴性细胞系Mel285中,Brn-2对启动子活性无影响（P>0.05）。结论　Brn-2表达于人脉络膜黑色素瘤细胞,并下调阳性细胞系MART-1启动子活性。     

Insulin-like growth factor-1 receptor in uveal melanoma: a predictor for metastatic disease and a potential therapeutic target.

PURPOSE: To investigate the expression of the insulin-like growth factor-1 receptor (IGF-1R) with special focus on its role in cell growth in uveal melanoma. METHODS: Paraffin material from 36 clinicopathologically well characterized cases of primary uveal melanomas (18 of which had metastasized to the liver) with more than 15 years' follow-up was used for immunohistochemical analysis. In the experimental studies, three uveal melanoma cell lines (OCM-1, OCM-3, and 92-1) were used. The expression level of IGF-1R in the cell lines was modulated by glycosylation inhibitors, and the IGF-1R was neutralized with the antibody alphaIR-3. Expression of IGF-1R was assayed by Western blot analysis and immunohistochemistry. Cell growth and survival were analyzed by cell counting, thymidine incorporation, and viability assays. RESULTS: Western blot analysis and immunohistochemistry confirmed that IGF-1R is expressed in uveal melanoma. Although 10 of 18 patients who died of metastasizing disease showed high IGF-1R expression, only 5 of 18 tumors from patients who survived for 15 years or more after enucleation exhibited a high IGF-1R expression. Kaplan-Meier analysis showed a significant association (P = 0.035) between a high IGF-1R expression and death due to metastatic uveal melanoma. Using in vitro experimental models, we found that inhibition of the IGF-1R activity (tyrosine phosphorylation) was associated with a drastic decrease in uveal melanoma cell viability. CONCLUSIONS: These data suggest an important role of IGF-1R in uveal melanoma. The significant association between high IGF-1R expression and death due to metastatic disease may be explained by the fact that IGF-1 is mainly produced in the liver, which is the preferential site for uveal melanoma metastases. These data also point to the possibility of therapeutically interfering with IGF-1R, which appears to be expressed preferentially in uveal melanomas that appear to follow an aggressive clinical course.     

Cripto-1 expression in uveal melanoma: an immunohistochemical study

Human Cripto, the founder member of the epidermal growth factor-Cripto-FRL1-Cryptic (EGF-CFC) family, plays an important role during early embryonic development and in particular in carcinogenesis and the development of cancer metastases. Cripto-1 is over-expressed in most cancers, but is absent or only weakly expressed in normal cells. For this reason, Cripto-1 could be of potential value in the targeted treatment. There is no information on the expression of Cripto-1 in human uveal melanoma. Cripto-1 reactivity was evaluated by immunohistochemistry on 36 archival uveal melanomas using the polyclonal antibody to Cripto-1. The tumors were divided in to 2 groups. There were 18 uveal melanomas with no intrascleral or extrascleral extension and 18 uveal melanomas with intrascleral/extrascleral extension/liver metastasis. Cripto-1 reactivity was correlated with tumor aggressiveness and cell type. Furthermore, we studied the immunolocalization of Cripto-1 in 4 uveal melanoma cell lines OCM-1, OCM-8, and 92-1, and OMM-1 and in 2 primary uveal melanocyte cultures. Cripto-1 was expressed in both the non-invasive and aggressive uveal melanomas. Cripto-1 was positive in the 4 uveal melanoma cell lines and absent in the primary uveal melanocyte cultures. Retinal tissue did not express Cripto-1. The results suggest that Cripto-1 is expressed in uveal melanoma, negative in the non-neoplastic ocular tissue and point to its use as a target for therapy.     

Angiogenic profile of uveal melanoma

Uveal melanoma develops in one of the most capillary-rich tissues of the body and is disseminated hematogenously. Knowledge of the nature and the spatiotemporal expression of angiogenic factors in uveal melanoma is essential to the development of new treatment strategies, especially with regard to improving survival. In this study, we measured the angiogenic potential of several angiogenic factors in different uveal melanoma cell lines, in an in vivo model, and in primary tumor material from patients with melanoma. Most uveal melanoma cell lines expressed vascular endothelial growth factor (VEGF)-A (isoforms 121, 165, 189), VEGF-B, VEGF-C, VEGF-D, and basic fibroblastic growth factor (b-FGF) to various extents. The expression of VEGF-A 121 was always higher than that of the other VEGF-A isoforms, suggesting that VEGF-A 121 is the most abundant VEGF-A isoform. All experimentally induced tumors expressed VEGF-A, VEGF-B, VEGF-C, VEGF-D, and basic fibroblastic growth factor (b-FGF). Similarly, significant amounts of mRNA for VEGF-B, VEGF-C, VEGF-D, and b-FGF were detected in uveal melanoma material from patients. In contrast, VEGF-A mRNA (121, 165, 189) was low (9/28) or not detectable in the tumor samples. The synthesis of VEGF-A 165 and b-FGF protein by various cell lines was measured by enzyme-linked immunosorbent assay (ELISA). Most uveal melanoma cell lines, but not normal melanocytes, strongly synthesized and secreted VEGF-A 165 and b-FGF during cell culture. Our data suggest that the expression of (lymph) angiogenic factors may play a causal role in the angiogenesis and progression of uveal melanoma and distant metastasis.     

Genetics of primary intraocular tumors

Primary intraocular neoplasms are tumors that originate within the eye. The most common malignant primary intraocular tumor in adults is uveal melanoma and the second is primary intraocular lymphoma or vitreoretinal (intraocular) lymphoma. The most common malignant intraocular tumor in children is retinoblastoma. Genetics plays a vital role in the diagnosis and detection of ocular tumors. In uveal melanoma, monosomy 3 is the most common genetic alteration and somatic mutations of BAP1, a tumor suppressor gene, have been reported in nearly 50% of primary uveal melanomas. The retinoblastoma gene RB1 is the prototype tumor suppressor gene-mutations in RB1 alleles lead to inactivated RB protein and the development of retinoblastoma. Immunoglobulin heavy chain (IgH) or T-cell receptor (TCR) gene rearrangement is observed in B-cell or T-cell primary vitreoretinal lymphoma, respectively. Other factors related to the genetics of these three common malignancies in the eye are discussed and reviewed.     

Uveal melanoma expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors and susceptibility to TRAIL-induced apoptosis

PURPOSE: The study had two purposes: to examine the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors on uveal melanoma cells and metastases arising from uveal melanoma and to determine the susceptibility of uveal melanoma cells to TRAIL-induced apoptosis. METHODS: Nine human uveal melanoma cell lines and three cell lines derived from uveal melanoma metastases were examined for TRAIL receptor expression by flow cytometry. In vitro apoptosis assays were performed to determine the relative susceptibility of uveal melanoma cells to TRAIL-induced apoptosis. Annexin V staining was also used to determine the capacity of either cycloheximide or interferon-beta to enhance TRAIL-induced apoptosis. RESULTS: Five of the nine uveal melanoma cell lines expressed TRAIL-R2 on more than 60% of the cells. All three of the cell lines derived from uveal melanoma metastases expressed TRAIL-R2 on more than 50% of the cells. Cycloheximide exerted a profound effect in enhancing TRAIL-induced apoptosis in all but two of the uveal melanoma cell lines and in all three of the metastases cell lines. Interferon-beta produced a similar enhancement of TRAIL-induced apoptosis, even in cell lines that were previously shown to be resistant. CONCLUSIONS: TRAIL is a potentially useful therapeutic modality for the management of uveal melanomas and their metastases. Moreover, pharmacological agents and biological response modifiers that independently display antineoplastic properties can enhance TRAIL-induced apoptosis in resistant uveal melanoma cells.