Genetic markers of pigmentation are novel risk loci for uveal melanoma

Estimation of genetic variation in vitiligo associated genes: Population genomics perspective

BACKGROUND

Vitiligo is an auto-immune progressive depigmentation disorder of the skin due to loss of melanocytes. Genetic risk is one of the important factors for development of vitiligo. Preponderance of vitiligo in certain ethnicities is known which can be analysed by understanding the distribution of allele frequencies across normal populations. Earlier GWAS identified 108 risk alleles for vitiligo in Europeans and East Asians. In this study, 64 of these risk alleles were used for analysing their enrichment and depletion across populations (1000 Genomes Project and IndiGen) with reference to 1000 Genomes dataset. Genetic risk scores were calculated and Fisher's exact test was performed to understand statistical significance of their variation in each population with respect to 1000 Genomes dataset as reference. In addition to SNPs reported in GWAS, significant variation in allele frequencies of 1079 vitiligo-related genes were also analysed. Two-tailed Chi-square test and Bonferroni's multiple adjustment values along with fixation index (≥ 0.5) and minimum allele frequency (≥ 0.05) were calculated and used to prioritise the variants based on pairwise comparison across populations.

RESULTS

Risk alleles rs1043101 and rs10768122 belong to 3 prime UTR of glutamate receptor gene SLC1A2 are found to be highly enriched in the South Asian population when compared with the 'global normal' population. Intron variant rs4766578 (ATXN2) was found to be deleted in SAS, EAS and AFR and enriched in EUR and AMR1. This risk allele is found to be under positive selection in SAS, AMR1 and EUR. From the ancillary vitiligo gene list, nonsynonymous variant rs16891982 was found to be enriched in the European and the Admixed American populations and depleted in all others. rs2279238 and rs11039155 belonging to the LXR-α gene involved in regulation of metalloproteinase 2 and 9 (melanocyte precursors) were found to be associated with vitiligo in the North Indian population (in earlier study).

CONCLUSION

The differential enrichment/depletion profile of the risk alleles provides insight into the underlying inter-population variations. This would provide clues towards prioritisation of SNPs associated with vitiligo thereby elucidating its preponderance in different ethnic groups.

Uveal melanoma: Current evidence on prognosis, treatment and potential developments

Uveal Melanoma (UM) is a rare disease, yet it is the most common primary intraocular malignancy in adult patients. Despite continuous advancements and research, the risk of metastasis remains high. It is possible to stratify patients according to their risk of metastases using a variety of known risk factors. Even though there is no gold standard for the prognostication of patients with uveal melanoma, it is becoming increasingly clear that combining histo-pathological, patient-related and molecular prognostic markers allows a more accurate prediction of the metastatic risk than by using one parameter. Primary UM in the eye are treated very effectively with eye-sparing radiation-based techniques or enucleation. However, it is not yet possible to prevent or treat metastases with the current therapeutic options. Nonetheless, the efforts to find new therapeutic targets continue and progress is being made, especially in the field of targeted therapy, as exemplified by the anti-gp100 bispecific molecule Tebentafusp. This review delves into the history of uveal melanoma, its incidence, presentation and diagnosis, the known prognostic factors and the treatment options, both for the primary tumour and for metastases. We show that different populations may have different risks for developing UM, and that each country should evaluate their own patients.

Worldwide Incidence of Ocular Melanoma and Correlation With Pigmentation-Related Risk Factors

Purpose

The worldwide incidence of ocular melanoma (OM), uveal melanoma (UM), and conjunctival melanoma has last been reported on 15 years ago. Recently, light iris color and four specific single-nucleotide-polymorphisms (SNPs) have been identified as a UM-risk factor. Furthermore, six iris color predicting SNPs have been discovered (IrisPlex). Interestingly, two of these (rs129138329 and rs12203592) are also UM-risk factors. We collected worldwide incidence data of OM and investigated its correlations with iris color, IrisPlex SNPs, and UM-risk SNPs.

Methods

Cases of OM, as defined by the International Classification of Diseases Oncology C69 (eye), 8720/3 to 8790/3 (malignant melanoma), and 8000 to 8005 (malignant neoplasm), between 1988 and 2012, were extracted from the Cancer Incidence in Five Continents. Incidence rates were age-standardized and their trends were analyzed with joinpoint regression and age period cohort modeling. Frequencies for each country of iris color, IrisPlex SNPs, and UM-risk SNPs were collected from the literature.

Results

Incidence rates were generally ≥8.0 cases per million person-years in Northern Europe, Western Europe, and Oceania; 2.0 to 7.9 in North America, Eastern Europe, and Southern Europe; and <2.0 in South America, Asia, and Africa. OM incidence correlated with latitude (r = 0.77, P ≤ 0.001) and is expressed as a north-to-south decreasing gradient in Europe. SNP rs12913832 correlated with OM incidence (r = 0.83, P ≤ 0.001), blue iris color (r = 0.56, P ≤ 0.05), green iris color (r = 0.51, P ≤ 0.05), and brown iris color (r = -0.64, P ≤ 0.01). Trends were stable for most countries (28/35).

Conclusions

OM incidence is highest in populations of European ancestry and lowest in populations of Asian and African ancestry. Overall, trends are stable, and the spatial correlation among OM incidence, iris color, and rs12913832 may support the role of pigmentation-related risk factors in OM development.

Prognostic significance of melanogenesis pathway and its association with the ultrastructural characterisation of melanosomes in uveal melanoma

BACKGROUND

Pigmentation could be a relevant prognostic factor in uveal melanoma (UM) development. Microphthalmia-associated transcription factor (MITF) regulates melanin synthesis by activating tyrosinase-related protein 2 (TYRP2) and silver protein (SILV) that induce the melanogenesis pathway. Although their oncogenic potential has been observed in various malignancies but has not been investigated in UM Asian population. Our aim is to study the ultrastructure of melanosomes and the prognostic significance of pigmentation markers such as TYRP2, MITF and SILV in UM.

METHODS

Transmission electron microscopy was performed to compare the ultrastructure of melanosomes in the normal choroid and UM cases. Immunoexpression of TYRP2, SILV and MITF was analysed in 82 UM samples. The mRNA expression level of all genes was measured in 70 UM cases. A statistical correlation was performed to determine the prognostic significance of all markers.

RESULTS

Premelanosomes and mature melanosomes undergoing dedifferentiation were observed in high-pigmented UM cases as compared with low-pigmented UM cases. Seventy per cent of UM cases showed high SILV expression while TYRP2 and MITF expression was present in 58% and 56% of cases, respectively. At the mRNA level, upregulation of TYRP2, SILV and MITF markers was seen in around 50% of UM cases, which was statistically significant with high pigmentation. Reduced metastatic-free survival was statistically significant with the MITF protein expression.

CONCLUSION

Our results demonstrated that ultrastructural changes in melanosomes and high expression of TYRP2, MITF and SILV could dysregulate the melanogenesis pathway and might be responsible for the aggressive behaviour of UM.

Analysis of uveal melanomas and paired constitutional DNA for exclusion of a BAP1-tumor predisposition syndrome

Uveal melanoma (UM) is a rare tumor originating from melanocytic cells in the eye. Familial aggregation of UM is rare and can occur as part of the tumor predisposition syndrome BAP1-TPDS. However, family history alone will only identify a subset of patients with BAP1-TPDS. In the present study, we used sequential testing of tumor and blood DNA from UM patients for differential diagnosis of BAP1-TPDS. The study group was an unselected prospective cohort of patients from whom UM tissue was available. First, chromosome 3 status in tumor DNA was determined in all 140 patients who consented to participate. As tumors with disomy 3 rarely show BAP1 alterations, sequence analysis of this gene was performed in the 72 tumors with monosomy 3 (M3) or partial M3 only. We identified oncogenic BAP1 alterations in 52 of these tumors (72%). Targeted sequencing of DNA from matched peripheral blood showed pathogenic variants in two patients (3.8%) thus proving BAP1-TPDS. Only one of these two patients also had a medical history suggestive of this syndrome. Conversely, in three patients known to have had additional tumors before diagnosis of UM, constitutional heterozygosity for a BAP1 mutation was excluded. Altogether, in 50 patients we could exclude BAP1-TPDS with high diagnostic certainty. The results of our study support that genetic testing for BAP1-TPDS should be offered to all patients with UM. Moreover, as genetic information from the tumor can help exclude heritable risk, the strategy for analysis should include efforts to obtain tumor samples for testing.

Increased histological tumour pigmentation in Uveal Melanoma is related to eye colour and loss of chromosome 3/BAP1

Purpose

Heavy pigmentation is known to be a prognostic risk factor in uveal melanoma (UM). We analyzed whether genetic tumor parameters were associated with tumor pigmentation and whether pigmentation should be included in prognostic tests.

Design

Retrospective comparison of clinical, histopathological, and genetic features and survival in UM with different pigmentation.

Participants

A total of 1058 patients with UM from a White European population with diverse eye colors enucleated between 1972 and 2021.

Methods

Cox regression and log-rank tests were used for survival analysis; the chi-square test and Mann-Whitney U test were used for correlation analysis.

Main Outcome Measures

Uveal melanoma-related survival based on tumor pigmentation and chromosome status, correlation of tumor pigmentation with prognostic factors.

Results

The 5-year UM-related mortality was 8% in patients with nonpigmented tumors (n = 54), 25% with lightly pigmented tumors (n = 489), 41% with moderately pigmented tumors (n = 333), and 33% with dark tumors (n = 178) (P < 0.001). The percentage of tumors with monosomy 3 (M3) or 8q gain increased with increasing pigmentation (31%, 46%, 62%, and 70% having M3 [P < 0.001], and 19%, 43%, 61%, and 63% having 8q gain [P < 0.001] in the 4 increasing pigment groups, respectively). BRCA-associated protein 1 (BAP1) loss (known for 204 cases) was associated with increased tumor pigmentation (P = 0.001). Cox regression analysis on survival showed that when chromosome status and pigmentation were both included, pigmentation was not an independent prognostic indicator. Preferentially expressed antigen in melanoma (PRAME) expression was a significant prognostic marker in light tumors (P = 0.02) but not in dark tumors (P = 0.85).

Conclusions

Patients with moderately and heavily pigmented tumors showed a significantly higher UM-related mortality than patients with unpigmented and light tumors (P < 0.001), supporting prior reports on the relation between increased tumor pigmentation and a worse prognosis. Although we previously showed that a dark eye color was associated with tumor pigmentation, we now show that the tumor's genetic status (chromosome 3 and 8q/BAP1 status) is also related to tumor pigmentation. When pigmentation and chromosome 3 status are both included in a Cox regression analysis, pigmentation is not an independent prognostic factor. However, evidence from this and previous studies shows that chromosome changes and PRAME expression have a stronger association with survival when they occur in light tumors than in dark ones. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references.

MITF in Normal Melanocytes, Cutaneous and Uveal Melanoma: A Delicate Balance

Microphthalmia-associated transcription factor (MITF) is an important regulator of melanogenesis and melanocyte development. Although it has been studied extensively in cutaneous melanoma, the role of MITF in uveal melanoma (UM) has not been explored in much detail. We review the literature about the role of MITF in normal melanocytes, in cutaneous melanoma, and in UM. In normal melanocytes, MITF regulates melanocyte development, melanin synthesis, and melanocyte survival. The expression profile and the behaviour of MITF-expressing cells suggest that MITF promotes local proliferation and inhibits invasion, inflammation, and epithelial-to-mesenchymal (EMT) transition. Loss of MITF expression leads to increased invasion and inflammation and is more prevalent in malignant cells. Cutaneous melanoma cells switch between MITF-high and MITF-low states in different phases of tumour development. In UM, MITF loss is associated with loss of BAP1 protein expression, which is a marker of poor prognosis. These data indicate a dual role for MITF in benign and malignant melanocytic cells.

Different Pigmentation Risk Loci for High-Risk Monosomy 3 and Low-Risk Disomy 3 Uveal Melanomas

BACKGROUND

Uveal melanoma (UM), a rare malignant tumor of the eye, is predominantly observed in populations of European ancestry. UMs carrying a monosomy 3 (M3) frequently relapse mainly in the liver, whereas UMs with disomy 3 (D3) are associated with more favorable outcome. Here, we explored the UM genetic predisposition factors in a large genome-wide association study (GWAS) of 1142 European UM patients and 882 healthy controls .

METHODS

We combined 2 independent datasets (Global Screening Array) with the dataset described in a previously published GWAS in UM (Omni5 array), which were imputed separately and subsequently merged. Patients were stratified according to their chromosome 3 status, and identified UM risk loci were tested for differential association with M3 or D3 subgroups. All statistical tests were 2-sided.

RESULTS

We recapitulated the previously identified risk locus on chromosome 5 on CLPTM1L (rs421284: odds ratio [OR] =1.58, 95% confidence interval [CI] = 1.35 to 1.86; P = 1.98 × 10-8) and identified 2 additional risk loci involved in eye pigmentation: IRF4 locus on chromosome 6 (rs12203592: OR = 1.76, 95% CI = 1.44 to 2.16; P = 3.55 × 10-8) and HERC2 locus on chromosome 15 (rs12913832: OR= 0.57, 95% CI = 0.48 to 0.67; P = 1.88 × 10-11). The IRF4 rs12203592 single-nucleotide polymorphism was found to be exclusively associated with risk for the D3 UM subtype (ORD3 = 2.73, 95% CI = 1.87 to 3.97; P = 1.78 × 10-7), and the HERC2 rs12913832 single-nucleotide polymorphism was exclusively associated with risk for the M3 UM subtype (ORM3 = 2.43, 95% CI = 1.79 to 3.29; P = 1.13 × 10-8). However, the CLPTM1L risk locus was equally statistically significant in both subgroups.

CONCLUSIONS

This work identified 2 additional UM risk loci known for their role in pigmentation. Importantly, we demonstrate that UM tumor biology and metastatic potential are influenced by patients' genetic backgrounds.

Uveal Melanoma Metastasis

Uveal melanoma (UM) is characterized by relatively few, highly incident molecular alterations and their association with metastatic risk is deeply understood. Nevertheless, this knowledge has so far not led to innovative therapies for the successful treatment of UM metastases or for adjuvant therapy, leaving survival after diagnosis of metastatic UM almost unaltered in decades. The driver mutations of UM, mainly in the G-protein genes GNAQ and GNA11, activate the MAP-kinase pathway as well as the YAP/TAZ pathway. At present, there are no drugs that target the latter and this likely explains the failure of mitogen activated kinase kinase inhibitors. Immune checkpoint blockers, despite the game changing effect in cutaneous melanoma (CM), show only limited effects in UM probably because of the low mutational burden of 0.5 per megabase and the unavailability of antibodies targeting the main immune checkpoint active in UM. The highly pro-tumorigenic microenvironment of UM also contributes to therapy resistance. However, T-cell redirection by a soluble T-cell receptor that is fused to an anti-CD3 single-chain variable fragment, local, liver specific therapy, new immune checkpoint blockers, and YAP/TAZ specific drugs give new hope to repeating the success of innovative therapy obtained for CM.

Chromosome 3 and 8q aberrations in Uveal Melanoma show greater impact on survival in patients with light iris versus dark iris color

PURPOSE

Individuals with gray, blue, or green iris have a higher chance of developing uveal melanoma (UM) than those with brown eyes. We wondered whether iris pigmentation might not only be related to predisposition to UM, but also to its behavior and therefore compared clinical, histopathologic, and genetic characteristics of UM between eyes with different iris colors.

DESIGN

We determined iris color in a large cohort of patients who had undergone an enucleation for UM. Clinical and histopathological tumor characteristics, chromosome status, and survival were compared between three groups, based on iris color.

PARTICIPANTS

412 patients with choroidal/ciliary body UM, who had undergone primary enucleation at the Leiden University Medical Center (LUMC), Leiden, The Netherlands, between 1993 and 2019, divided into three groups, based on iris color (gray/blue, green/hazel, and brown). Validation cohort: 934 choroidal/ciliary body UM patients treated at Wills Eye Hospital (WEH), Philadelphia, United States.

METHODS

Comparison of clinical, histopathologic, and genetic characteristics of UM in patients with different iris colors.

MAIN OUTCOME MEASURES

Melanoma-related survival in UM patients, divided over three iris color groups, in relation to the tumor's chromosome 3 and 8q status.

RESULTS

Moderate and heavy tumor pigmentation was especially seen in eyes with brown iris (p < 0.001). Survival did not differ between patients with different iris colors (p = 0.28). However, in patients with a light iris, copy number changes in chromosome 3 and 8q had a greater influence on survival than in patients with a dark iris. Similarly, chromosome 3 and chromosome 8q status affected survival more among patients with lightly-pigmented tumors than in patients with heavily-pigmented tumors. The WEH cohort similarly showed a greater influence of chromosome aberrations in light-eyed individuals.

CONCLUSIONS

While iris color by itself did not relate to survival of UM patients, chromosome 3 and 8q aberrations had a much larger influence on survival in patients with light iris compared to those with brown iris. This suggests a synergistic effect of iris pigmentation and chromosome status in the regulation of oncogenic behavior of UM. Iris color should be taken into consideration when calculating the risk for developing metastases.

Iris Colour and the Risk of Developing Uveal Melanoma

Uveal melanoma (UM) is a global disease which especially occurs in elderly people. Its incidence varies widely between populations, with the highest incidence among Caucasians, and a South-to-North increase in Europe. As northern Europeans often have blond hair and light eyes, we wondered whether iris colour may be a predisposing factor for UM and if so, why. We compared the distribution of iris colour between Dutch UM patients and healthy Dutch controls, using data from the Rotterdam Study (RS), and reviewed the literature regarding iris colour. We describe molecular mechanisms that might explain the observed associations. When comparing a group of Dutch UM patients with controls, we observed that individuals from Caucasian ancestry with a green/hazel iris colour (Odds Ratio (OR) = 3.64, 95% Confidence Interval (CI) 2.57-5.14) and individuals with a blue/grey iris colour (OR = 1.38, 95% CI 1.04-1.82) had a significantly higher crude risk of UM than those with brown eyes. According to the literature, this may be due to a difference in the function of pheomelanin (associated with a light iris colour) and eumelanin (associated with a brown iris colour). The combination of light-induced stress and aging may affect pheomelanin-carrying melanocytes in a different way than eumelanin-carrying melanocytes, increasing the risk of developing a malignancy.

Prognostic impact of HERC2 protein and pink-eyed dilution protein in uveal melanoma

Biological understanding of pigmentation and its association with clinicopathological implications in uveal melanoma (UM) risk is still unexplored. HECT and RLD Domain Containing E3 Ubiquitin Protein Ligase 2 (HERC2) and Pink-eyed dilution protein (P-protein) are the important markers that regulate pigmentation in eye. Therefore, our aim of the study was to investigate the expression of HERC2 and P-protein in the UM patients and correlate with patient outcome. Fifty-two formalin-fixed paraffin-embedded UM tissue samples were included to detect the expression of HERC2 and P-protein by immunohistochemistry and validated by western blot. Cox proportional hazard model and log-rank test were used to determine the prognostic potential of these proteins. High pigmentation was seen in 67% of the UM cases. The expression of HERC2 and P-protein was present in 44% and 71% cases, respectively. On statistical analysis, increased pigmentation, epithelioid cell type, and ciliary body invasion were significant with the protein expressions (p < 0.05). Metastasis-free survival was reduced in UM cases which expressed HERC2 and P-protein. On multivariate analysis, P-protein expression was found to be an independent prognostic factor. Our findings suggest that HERC2 and P-protein could be used as novel predictors of high pigmentation in UM cases which have high metastatic potential.

HERC Ubiquitin Ligases in Cancer

HERC proteins are ubiquitin E3 ligases of the HECT family. The HERC subfamily is composed of six members classified by size into large (HERC1 and HERC2) and small (HERC3-HERC6). HERC family ubiquitin ligases regulate important cellular processes, such as neurodevelopment, DNA damage response, cell proliferation, cell migration, and immune responses. Accumulating evidence also shows that this family plays critical roles in cancer. In this review, we provide an integrated view of the role of these ligases in cancer, highlighting their bivalent functions as either oncogenes or tumor suppressors, depending on the tumor type. We include a discussion of both the molecular mechanisms involved and the potential therapeutic strategies.

Uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. UMs are usually initiated by a mutation in GNAQ or GNA11, unlike cutaneous melanomas, which usually harbour a BRAF or NRAS mutation. The annual incidence in Europe and the USA is ~6 per million population per year. Risk factors include fair skin, light-coloured eyes, congenital ocular melanocytosis, ocular melanocytoma and the BAP1-tumour predisposition syndrome. Ocular treatment aims at preserving the eye and useful vision and, if possible, preventing metastases. Enucleation has largely been superseded by various forms of radiotherapy, phototherapy and local tumour resection, often administered in combination. Ocular outcomes are best with small tumours not extending close to the optic disc and/or fovea. Almost 50% of patients develop metastatic disease, which usually involves the liver, and is usually fatal within 1 year. Although UM metastases are less responsive than cutaneous melanoma to chemotherapy or immune checkpoint inhibitors, encouraging results have been reported with partial hepatectomy for solitary metastases, with percutaneous hepatic perfusion with melphalan or with tebentafusp. Better insight into tumour immunology and metabolism may lead to new treatments.

Regulation of the MDM2-p53 pathway by the ubiquitin ligase HERC2

The p53 tumor suppressor protein is a transcription factor that plays a prominent role in protecting cells from malignant transformation. Protein levels of p53 and its transcriptional activity are tightly regulated by the ubiquitin E3 ligase MDM2, the gene expression of which is transcriptionally regulated by p53 in a negative feedback loop. The p53 protein is transcriptionally active as a tetramer, and this oligomerization state is modulated by a complex formed by NEURL4 and the ubiquitin E3 ligase HERC2. Here, we report that MDM2 forms a complex with oligomeric p53, HERC2, and NEURL4. HERC2 knockdown results in a decline in MDM2 protein levels without affecting its protein stability, as it reduces its mRNA expression by inhibition of its promoter activation. DNA damage induced by bleomycin dissociates MDM2 from the p53/HERC2/NEURL4 complex and increases the phosphorylation and acetylation of oligomeric p53 bound to HERC2 and NEURL4. Moreover, the MDM2 promoter, which contains p53-response elements, competes with HERC2 for binding of oligomeric, phosphorylated and acetylated p53. We integrate these findings in a model showing the pivotal role of HERC2 in p53-MDM2 loop regulation. Altogether, these new insights in p53 pathway regulation are of great interest in cancer and may provide new therapeutic targets.

Advanced choroidal melanoma with a desirable aesthetic outcome after enucleation: A case report

Choroidal melanoma is a rare ocular tumor. The present study reports the case of a 66-year-old male who presented with chronic headache and progressive visual loss. Physical eye examination and combined A- and B-mode ultrasonography detected choroidal melanoma. Due to tumor characteristics the eye was enucleated restoring the orbital volume with a 22 mm intraorbital bioceramic sphere implant. The eye was subjected to histopathological examination that confirmed the choroidal melanoma, 2 cm in diameter and 0.8 cm in elevation, occupying almost half of the globe. Microscopically, the neoplasm comprises mostly of epithelioid cells and fewer Type B spindle cells, with intense pigmentation. AJCC staging for the melanoma was T4b. The patient was fitted with an artificial eye after enucleation. Thirteen months after initial diagnosis, liver metastases were confirmed during his scheduled follow-up.

Characteristics of melanoma in Japan: a nationwide registry analysis 2011-2013

The distribution and incidence of melanoma vary among different races and ethnic groups. This study aimed to investigate the characteristics of cutaneous melanoma, mucosal melanoma, uveal melanoma, and melanoma of unknown primary (MUP) origin in a Japanese population. We studied these four types of melanoma in patients registered in Hospital Based Cancer Registries in Japan from 2011 to 2013. A total of 5566 patients with melanoma were identified. The distribution of sex, age, primary site, and clinical stage was analyzed. The number of patients, proportion in comparison with all melanoma cases, and crude incidence rate per 100 000 person-year of each melanoma type were 4481, 80.5%, and 1.24 in invasive cutaneous; 821, 14.8%, and 0.32 in mucosal; 163, 2.9%, and 0.064 in uveal; and 101, 1.8%, and 0.039 in MUP origin, respectively. Including the patients with in-situ cutaneous melanoma and stage unknown cutaneous melanoma, the crude incidence rate of cutaneous melanoma increased at 1.75. Almost half of the cutaneous melanomas were located in the lower limb. Cutaneous melanoma was the most common, but less frequent than that in western countries. Mucosal melanoma was quite rare, but its proportion and crude incidence rate were higher than those in western countries. Uveal melanoma was particularly rare, and its crude incidence rate was lower than that in western countries. MUP origin was also particularly rare, but it had almost the same incidence rate as that in other countries. Melanoma in Japan was heterogeneous among the four melanoma types and shares some attributes with that in western countries.

Genes and genetics in eye diseases: a genomic medicine approach for investigating hereditary and inflammatory ocular disorders

Past 25y have witnessed an exponential increase in knowledge and understanding of ocular diseases and their respective genetic underpinnings. As a result, scientists have mapped many genes and their variants that can influence vision and health of our eyes. Based on these findings, it is becoming clear that an early diagnosis employing genetic testing can help evaluate patients' conditions for instituting treatment plan(s) and follow-up care to avoid vision complications later. For example, knowing family history becomes crucial for inherited eye diseases as it can benefit members in family who may have similar eye diseases or predispositions. Therefore, gathering information from an elaborate examination along with complete assessment of past medical illness by ophthalmologists followed by consultation with geneticists can help create a roadmap for making diagnosis and treatment precise and beneficial. In this review, we present an update on ocular genomic medicine that we believe has tremendous potential towards unraveling genetic implications in ocular diseases and patients' susceptibilities. We also discuss translational aspects of genetic ophthalmology and genome engineering that may help advance molecular diagnostics and therapeutics.

Focus on cutaneous and uveal melanoma specificities

Cutaneous melanoma (CM) and uveal melanoma (UM) derive from cutaneous and uveal melanocytes that share the same embryonic origin and display the same cellular function. However, the etiopathogenesis and biological behaviors of these melanomas are very different. CM and UM display distinct landscapes of genetic alterations and show different metastatic routes and tropisms. Hence, therapeutic improvements achieved in the last few years for the treatment of CM have failed to ameliorate the clinical outcomes of patients with UM. The scope of this review is to discuss the differences in tumorigenic processes (etiologic factors and genetic alterations) and tumor biology (gene expression and signaling pathways) between CM and UM. We develop hypotheses to explain these differences, which might provide important clues for research avenues and the identification of actionable vulnerabilities suitable for the development of new therapeutic strategies for metastatic UM.

A GWAS in uveal melanoma identifies risk polymorphisms in the CLPTM1L locus

Uveal melanoma, a rare malignant tumor of the eye, is predominantly observed in populations of European ancestry. A genome-wide association study of 259 uveal melanoma patients compared to 401 controls all of European ancestry revealed a candidate locus at chromosome 5p15.33 (region rs421284: OR = 1.7, CI 1.43-2.05). This locus was replicated in an independent set of 276 cases and 184 controls. In addition, risk variants from this region were positively associated with higher expression of CLPTM1L. In conclusion, the CLPTM1L region contains risk alleles for uveal melanoma susceptibility, suggesting that CLPTM1L could play a role in uveal melanoma oncogenesis.

Uveal Melanoma: Identifying Immunological and Chemotherapeutic Targets to Treat Metastases

Uveal melanoma is an intraocular malignancy that, depending on its size and genetic make-up, may lead to metastases in up to 50% of cases. Currently, no therapy has been proven to improve survival. However, new therapies exploiting immune responses against metastases are being developed. The primary tumor is well characterized: tumors at high risk of developing metastases often contain macrophages and lymphocytes. However, these lymphocytes are often regulatory T cells that may suppress immune response. Currently, immune checkpoint inhibitors have shown marked efficacy in multiple cancers (eg, cutaneous melanoma) but do not yet improve survival in uveal melanoma patients. More knowledge needs to be acquired regarding the function of T cells in uveal melanoma. Other therapeutic options are related to the biochemical pathways. Targeting the RAF-MEK-ERK pathway with small molecule MEK inhibitors abrogates the growth of UM cells harboring GNAQ/GNA11 Q209 mutations, suggesting that these aberrant G-protein oncogenes mediate, at least in part, their effect through this hallmark proliferation pathway. Other pathways are also implicated, such as those involving c-Jun and YAP. Further studies may show how interference in the different pathways may affect survival.

The biology of uveal melanoma

Uveal melanoma (UM), a rare cancer of the eye, is distinct from cutaneous melanoma by its etiology, the mutation frequency and profile, and its clinical behavior including resistance to targeted therapy and immune checkpoint blockers. Primary disease is efficiently controlled by surgery or radiation therapy, but about half of UMs develop distant metastasis mostly to the liver. Survival of patients with metastasis is below 1 year and has not improved in decades. Recent years have brought a deep understanding of UM biology characterized by initiating mutations in the G proteins GNAQ and GNA11. Cytogenetic alterations, in particular monosomy of chromosome 3 and amplification of the long arm of chromosome 8, and mutation of the BRCA1-associated protein 1, BAP1, a tumor suppressor gene, or the splicing factor SF3B1 determine UM metastasis. Cytogenetic and molecular profiling allow for a very precise prognostication that is still not matched by efficacious adjuvant therapies. G protein signaling has been shown to activate the YAP/TAZ pathway independent of HIPPO, and conventional signaling via the mitogen-activated kinase pathway probably also contributes to UM development and progression. Several lines of evidence indicate that inflammation and macrophages play a pro-tumor role in UM and in its hepatic metastases. UM cells benefit from the immune privilege in the eye and may adopt several mechanisms involved in this privilege for tumor escape that act even after leaving the niche. Here, we review the current knowledge of the biology of UM and discuss recent approaches to UM treatment.