Update on Metastatic Uveal Melanoma: Progress and Challenges

tRNA-derived fragments: Key determinants of cancer metastasis with emerging therapeutic and diagnostic potentials

Metastasis is a significant clinical challenge responsible for cancer mortality and non-response to treatment. However, the molecular mechanisms driving metastasis remain unclear, limiting the development of efficient diagnostic and therapeutic approaches. Recent breakthroughs in cancer biology have discovered a group of small non-coding RNAs called tRNA-derived fragments (tRFs), which play a critical role in the metastatic behavior of various tumors. tRFs are produced from cleavage modifications of tRNAs and have different functional classes based on the pattern of these modifications. They perform post-transcriptional regulation through microRNA-like functions, displacing RNA-binding proteins, and play a role in translational regulation by inducing ribosome synthesis, translation initiation, and epigenetic regulation. Tumor cells manipulate tRFs to develop and survive the tumor mass, primarily by inducing metastasis. Multiple studies have demonstrated the potential of tRFs as therapeutic, diagnostic, and prognostic targets for tumor metastasis. This review discusses the production and function of tRFs in cells, their aberrant molecular contributions to the metastatic environment, and their potential as promising targets for anti-metastasis treatment strategies.

Immunogenic profiling of metastatic uveal melanoma discerns a potential signature related to prognosis

BACKGROUND

Uveal melanoma (UM) is an aggressive intraocular malignant tumor. The present study aimed to identify the key genes associated with UM metastasis and established a gene signature to analyze the relationship between the signature and prognosis and immune cell infiltration. Later, a predictive model combined with clinical variables was developed and validated.

METHODS

Two UM gene expression profile chip datasets were downloaded from TCGA and GEO databases. Immune-related genes (IRGs) were obtained from IMPORT database. First, these mRNAs were intersected with IRGs, and weighted gene co-expression network analysis (WGCNA) was used to identify the co-expression of genes primarily associated with metastasis of UM. Univariate Cox regression analysis screened the genes related to prognosis. LASSO-Cox established a risk score to distinguish high-risk group and low-risk group. Then the GSEA enrichment pathway and immune cell infiltration of the two groups were compared. And combined with clinical variables, a predictive model was constructed. The time-dependent receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) curve were used to verify the stability and accuracy of the final predictive model, and a nomogram was then drawn.

RESULTS

The MEblack, MEpurple, and MEblue modules were significantly associated with the metastasis of UM patients (P value < 0.001, = 0.001, = 0.022, respectively). Four genes (UBXN2B, OTUD3, KAT8, LAMTOR2) were obtained by Pearson correlation analysis, weighted gene correlation network analysis (WGCNA), univariate Cox, and LASSO-Cox. And a novel prognostic risk score was established. Immune-related prognostic signature can well classify UM patients into high-risk and low-risk groups. Kaplan-Meier curve showed that the OS of high-risk patients was worse than that of low-risk patients. In addition, the risk score played an important role in evaluating the signaling pathway and immune cell infiltration of UM patients in high-risk and low-risk groups. Both the training set and validation set of the model showed good predictive accuracy in the degree of differentiation and calibration (e.g., 1-year overall survival: AUC = 0.930 (0.857-1.003)). Finally, a nomogram was established to serve in clinical practice.

SIGNIFICANCE

UM key gene signature and prognosis predictive model might provide insights for further investigation of the pathogenesis and development of UM at the molecular level, and provide theoretical basis for determining new prognostic markers of UM and immunotherapy.

Identification of a prognostic six-immune-gene signature and a nomogram model for uveal melanoma

BACKGROUND

To identify an immune-related prognostic signature and find potential therapeutic targets for uveal melanoma.

METHODS

The RNA-sequencing data obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. The prognostic six-immune-gene signature was constructed through least absolute shrinkage and selection operator and multi-variate Cox regression analyses. Functional enrichment analysis and single sample GSEA were carried out. In addition, a nomogram model established by integrating clinical variables and this signature risk score was also constructed and evaluated.

RESULTS

We obtained 130 prognostic immune genes, and six of them were selected to construct a prognostic signature in the TCGA uveal melanoma dataset. Patients were classified into high-risk and low-risk groups according to a median risk score of this signature. High-risk group patients had poorer overall survival in comparison to the patients in the low-risk group (p < 0.001). These findings were further validated in two external GEO datasets. A nomogram model proved to be a good classifier for uveal melanoma by combining this signature. Both functional enrichment analysis and single sample GSEA analysis verified that this signature was truly correlated with immune system. In addition, in vitro cell experiments results demonstrated the consistent trend of our computational findings.

CONCLUSION

Our newly identified six-immune-gene signature and a nomogram model could be used as meaningful prognostic biomarkers, which might provide uveal melanoma patients with individualized clinical prognosis prediction and potential novel treatment targets.

Metastatic uveal melanoma: The final frontier

Treatment of primary intraocular uveal melanoma has developed considerably, its driver genes are largely unraveled, and the ways to assess its risk for metastases are very precise, being based on an international staging system and genetic data. Unfortunately, the risk of distant metastases, which emerge in approximately one half of all patients, is unaltered. Metastases are the leading single cause of death after uveal melanoma is diagnosed, yet no consensus exists regarding surveillance, staging, and treatment of disseminated disease, and survival has not improved until recently. The final frontier in conquering uveal melanoma lies in solving these issues to cure metastatic disease. Most studies on metastatic uveal melanoma are small, uncontrolled, retrospective, and do not report staging. Meta-analyses confirm a median overall survival of 10-13 months, and a cure rate that approaches nil, although survival exceeding 5 years is possible, estimated 2% either with first-line treatment or with best supportive care. Hepatic ultrasonography and magnetic resonance imaging as surveillance methods have a sensitivity of 95-100% and 83-100%, respectively, to detect metastases without radiation hazard according to prevailing evidence, but computed tomography is necessary for staging. No blood-based tests additional to liver function tests are generally accepted. Three validated staging systems predict, each in defined situations, overall survival after metastasis. Their essential components include measures of tumor burden, liver function, and performance status or metastasis free interval. Age and gender may additionally influence survival. Exceptional mutational events in metastases may make them susceptible to checkpoint inhibitors. In a large meta-analysis, surgical treatment was associated with 6 months longer median overall survival as compared to conventional chemotherapy and, recently, tebentafusp as first-line treatment at the first interim analysis of a randomized phase III trial likewise provided a 6 months longer median overall survival compared to investigator's choice, mostly pembrolizumab; these treatments currently apply to selected patients. Promoting dormancy of micrometastases, harmonizing surveillance protocols, promoting staging, identifying predictive factors, initiating controlled clinical trials, and standardizing reporting will be critical steppingstones in reaching the final frontier of curing metastatic uveal melanoma.

SUMOylation regulates Rb hyperphosphorylation and inactivation in uveal melanoma

Small ubiquitin‐like modifier (SUMO)ylation is one of the posttranslational modifications and is implicated in many tumor types. Modulation of SUMOylation can affect tumor progression, but the underlying mechanisms remain unclear. Here, we show that, for the first time, in uveal melanoma (UM), the most common intraocular malignancy in adults, global SUMOylation is upregulated and participates in tumor growth. Inhibition of SUMOylation in UM is sufficient to reduce tumor growth both in vitro and in vivo. Furthermore, we found that retinoblastoma protein (Rb) is a target protein and a critical downstream effector of the upregulated SUMOylation activity in UM. Increased SUMOylation of the Rb protein leads to its hyperphosphorylation and inactivation in UM cells, promoting UM cell proliferation. In summary, our results provide novel insight into the mechanism underlying SUMOylation‐regulated tumor growth in UM.

Molecular Genetics of Intraocular Tumors

PURPOSE

To explore the value of molecular technologies in the pathologic evaluation, diagnosis, and treatment of retinoblastoma and uveal melanoma.

METHODS

Review of the peer-reviewed literature on the molecular pathology of primary intraocular tumors.

CONCLUSION

Molecular tests are playing an increasingly important role in the diagnosis of intraocular tumors. They provide information valuable for diagnosis, prognosis, screening regimens, genetic counselling, and treatment. These technologies are becoming easier, faster, and with higher sensitivity and accuracy.

IsomiRs and tRNA-derived fragments are associated with metastasis and patient survival in uveal melanoma

Uveal melanoma (UVM) is the most common primary intraocular malignancy in adults. With over 50% of patients developing metastatic disease, there is an unmet need for improved diagnostic and therapeutic options. Efforts to understand the molecular biology of the disease have revealed several markers that correlate with patient prognosis, including the copy number of chromosome 3, genetic alterations in the BAP1, EIF1AX and SF3B1 genes, and other transcriptional features. Here, we expand upon previous reports by comprehensively characterizing the short RNA-ome in 80 primary UVM tumor samples. In particular, we describe a previously unseen complex network involving numerous regulatory molecules that comprise microRNA (miRNAs), novel UVM-specific miRNA loci, miRNA isoforms (isomiRs), and tRNA-derived fragments (tRFs). Importantly, we show that the abundance profiles of isomiRs and tRFs associate with various molecular phenotypes, metastatic disease, and patient survival. Our findings suggest deep involvement of isomiRs and tRFs in the disease etiology of UVM. We posit that further study and characterization of these novel molecules will improve understanding of the mechanisms underlying UVM, and lead to the development of new diagnostic and therapeutic approaches.

Immunological Backbone of Uveal Melanoma: Is There a Rationale for Immunotherapy?

No standard treatment has been established for metastatic uveal melanoma (mUM). Immunotherapy is commonly used for this disease even though UM has not been included in phase III clinical trials with checkpoint inhibitors. Unfortunately, only a minority of patients obtain a clinical benefit with immunotherapy. The immunological features of mUM were reviewed in order to understand if immunotherapy could still play a role for this disease.

A novel four‑snoRNA signature for predicting the survival of patients with uveal melanoma

Uveal melanoma (UM), the predominant histological subtype of intraocular malignant tumors in adults, often results in high rates of mortality; effective prognostic signatures used to predict the survival of patients with UM are limited. Small nucleolar RNAs (snoRNAs) are emerging as important regulators in the processes of carcinogenesis and tumor progression, but knowledge of their application as prognostic markers in UM is limited. In the present study, the expression profiles of snoRNAs in UM were determined; a total of 60 snoRNAs were notably associated with the overall survival of patients with UM via univariate Cox survival analysis. Subsequently, a prognostic signature based on four snoRNAs was proposed, which retained their prognostic significance determined by a multivariate Cox survival analysis. The formula is as follows: ACA17 * (‑1.602) + ACA45 * 0.803 + HBII‑276 * 0.603 + SNORD12 * 1.348. Furthermore, the results of in silico analysis indicated that perturbation of the phototransduction, GABAergic synapse and amphetamine addiction pathways may be the potential molecular mechanisms underlying the poor prognosis of patients with UM. Collectively, the present study proposed a potential prognostic signature for patients with UM and the prospective mechanisms at the genome‑wide level were determined.

The risk of dermatological toxicities of combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma patients: a systematic review and meta-analysis

BACKGROUND

This meta-analysis was conducted to assess the risk of dermatological toxicities of combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma patients.

METHODS

We considered relevant prospective randomized phase I, II, and III trials of melanoma patients on the combined BRAF and MEK inhibition versus BRAF inhibition, describing events of rash, photosensitivity reaction (PR), hyperkeratosis (HK), alopecia, cutaneous squamous-cell carcinom(cSCC), skin papilloma(SP), pruritus, and hand-foot syndrome(HFS), as eligible for inclusion.

RESULTS

Eight trials comprising 3163 patients were included in the meta-analysis. The relative risks(RRs) of developing all-grade rash with combined BRAF and MEK inhibition versus BRAF inhibition was 1.59 (95%CI, 1.35-1.86, p < 0.00001), HK 0.33(95%CI, 0.16-0.66, p = 0.002), SP 0.09(95%CI, 0.04-0.24, p < 0.00001), alopecia 0.30(95%CI, 0.19-0.48, p < 0.00001), cSCC 0.23(95%CI, 0.17-0.31, p < 0.00001), HFS 0.18(95%CI, 0.13-0.26, p < 0.00001) and PR 0.40(95%CI, 0.26-0.61, p < 0.0001), while the RRs of high-grade dermatological toxicities from all included trials were: rash 0.54(95%CI, 0.20-1.43, p = 0.21), HK 0.18(95%CI, 0.06-0.53, p = 0.002), SP 0.14(95%CI, 0.02-1.16, p = 0.07), alopecia 0.72(95%CI, 0.14-3.62, p = 0.69), cSCC 0.23(95%CI, 0.17-0.33, p < 0.00001), HFS 0.40(95%CI, 0.08-2.06, p = 0.27), and PR 0.14(95%CI, 0.04-0.51, p = 0.003), respectly.

CONCLUSION

Our analysis of data has demonstrated that combined BRAF and MEK inhibitor-based treatment is associated with an increased risk of all-grade rash and a decreased risk of all-grade and high-grade HK, SP, alopecia, cSCC, HFS, and PR compared with single BRAF inhibitor alone in melanoma patients. Appropriate prevention and management are recommended.

Abnormally expressed JunB transactivated by IL-6/STAT3 signaling promotes uveal melanoma aggressiveness via epithelial-mesenchymal transition

Uveal melanoma (UM) is the most common primary intraocular tumor in adults, and it carries a high risk of metastasis and mortality. Various proinflammatory cytokines have been found to be significantly increased in the aqueous humor or vitreous fluid of UM patients; however, the role of these cytokines in UM metastasis remains elusive. In the present study, we found that long-term interleukin (IL)-6 exposure promoted the migration and invasion of UM cells, diminished cell–cell adhesion, and enhanced focal adhesion. Moreover, IL-6 treatment decreased the membranous epithelial marker TJP1 and increased the cytoplasmic mesenchymal marker Vimentin. Further investigation demonstrated that JunB played a critical role in IL-6-induced UM epithelial–mesenchymal transition (EMT). In UM cells, the expression of JunB was significantly up-regulated during the IL-6-driven EMT process. Additionally, JunB induction occurred at the transcriptional level in a manner dependent on phosphorylated STAT3, during which activated STAT3 directly bound to the JunB promoter. Importantly, the knockdown of STAT3 prevented the IL-6-induced EMT phenotype as well as cell migration and invasion, whereas JunB overexpression recovered the attenuated aggressiveness of UM cells. Similarly, with IL-6 stimulation, the stable overexpression of JunB strengthened the migratory and invasive capabilities of UM cells and induced the EMT-promoting factors (Snail, Twist1, matrix metalloproteinase (MMP)-2, MMP-14, and MMP-19). Analysis of The Cancer Genome Atlas (TCGA) database indicated that JunB was positively correlated with IL-6 and STAT3 in UM tissues. The present study proposes an IL-6/STAT3/JunB axis leading to UM aggressiveness by EMT, which illustrates the negative side of inflammatory response in UM metastasis.

ZEB1 Regulates Multiple Oncogenic Components Involved in Uveal Melanoma Progression

Human uveal melanoma (UM) is a major ocular malignant tumor with high risk of metastasis and requires multiple oncogenic factors for progression. ZEB1 is a zinc finger E-box binding transcription factor known for participating epithelial-mesenchymal transition (EMT), a critical cellular event for metastasis of malignant tumors of epithelium origin. ZEB1 is also expressed in UM and high expression of ZEB1 correlates with UM advancement, but has little effect on cell morphology. We show that spindle UM cells can become epithelioid but not vice versa; and ZEB1 exerts its tumorigenic effects by promoting cell dedifferentiation, proliferation, invasiveness, and dissemination. We provide evidence that ZEB1 binds not only to repress critical genes involving in pigment synthesis, mitosis, adherent junctions, but also to transactivate genes involving in matrix degradation and cellular locomotion to propel UM progression towards metastasis. We conclude that ZEB1 is a major oncogenic factor required for UM progression and could be a potential therapeutic target for treating UM in the clinic.