Mohamed H. Abdel-Rahman

Germline BAP1 mutation predisposes to uveal melanoma, lung adenocarcinoma, meningioma, and other cancers.

Objective To investigate the potential contribution of germline sequence alterations in the BAP1 gene in uveal melanoma (UM) patients with possible predisposition to hereditary cancer. Design A total of 53 unrelated UM patients with high risk for hereditary cancer and five additional family members of one proband were studied. Mutational screening was carried out by direct sequencing. Results Of the 53 UM patients studied, a single patient was identified with a germline BAP1 truncating mutation, c. 799 C→T (p.Q267X), which segregated in several family members and was associated with UM and other cancers. Biallelic inactivation of BAP1 and decreased BAP1 expression were identified in the UM, lung adenocarcinoma and meningioma tumours from three family members with this germline BAP1 mutation. Germline BAP1 variants of uncertain significance, likely non-pathogenic, were also identified in two additional UM patients. Conclusion This study reports a novel hereditary cancer syndrome caused by a germline BAP1 mutation that predisposes patients to UM, lung carcinoma, meningioma, and possibly other cancers. The results indicate that BAP1 is the candidate gene in only a small subset of hereditary UM, suggesting the contribution of other candidate genes.

High Frequency of Submicroscopic Hemizygous Deletion Is a Major Mechanism of Loss of Expression of PTEN in Uveal Melanoma

PURPOSEnAlthough cytogenetic aberrations at 10q have been reported in up to 27% of uveal melanomas, the role of PTEN in the pathogenesis of uveal melanoma is largely unknown. Our aim was to determine the frequency and clinical significance of PTEN alterations in uveal melanomas.nnnPATIENTS AND METHODSnWe examined PTEN expression using immunohistochemistry in 75 sporadic uveal melanomas, with an average follow-up of 89 months. Molecular cytogenetic alterations were studied using comparative genomic hybridization (CGH). Genotyping was carried out using an intragenic PTEN marker and two flanking markers. Mutational analysis of PTEN was also carried out.nnnRESULTSnOf the 75 tumors, 12 (16%) showed no PTEN immunostaining, 32 (42.7%) showed weak to moderate staining and the remaining 31 (38.2%) showed staining similar to the normal internal controls. Using CGH, only two (15.4%) of 13 samples showed any loss of 10q. However, in the 38 tumors with informative genotyping, we found that 29 (76.3%) had loss of heterozygosity (LOH) of at least one PTEN marker, and 15 (39.5%) showed LOH of at least two markers. Mutations in the coding region of PTEN were identified in four (11.4%) of 35 tumors. Further, loss of cytoplasmic PTEN expression by immunohistochemistry was associated with shortened disease-free survival (P = .029).nnnCONCLUSIONnThis is the first demonstration that PTEN is a tumor suppressor involved in uveal melanoma pathogenesis and may be associated with clinical outcome. Our data also suggest that submicroscopic deletion, but not large deletions, is the major mechanism of loss of PTEN expression in uveal melanomas.

Expanding the clinical phenotype of hereditary BAP1 cancer predisposition syndrome, reporting three new cases

The clinical phenotype of BAP1 hereditary cancer predisposition syndrome (MIM 614327) includes uveal melanoma (UM), cutaneous melanoma (CM), renal cell carcinoma (RCC), and mesothelioma. However, the frequency of the syndrome in patients with UM and the association with other cancers are still not clear. In this study, we screened 46 previously untested, unrelated UM patients with high risk for hereditary cancer for germline mutation in BAP1. We also studied four additional patients with a personal or family history suggestive of BAP1 hereditary cancer syndrome. We identified three patients with germline pathogenic mutations (c.2050 C>T, pGln684*; c.1182C>G, p.Tyr394*, and c.1882_1885delTCAC, p. Ser628Profs*8) in BAP1. Two of these three patients presented with UM and the third with a metastatic adenocarcinoma likely from a hepatic cholangiocarcinoma. Reported family histories included UM, mesothelioma, RCC, CM, and several other internal malignancies. The results of this study confirm the association between germline BAP1 mutation and predisposition to UM, mesothelioma, CM and RCC. However, other cancers, such as cholangiocarcinoma and breast carcinoma may be part of the phenotype of this hereditary cancer predisposition syndrome. In addition, the results support the existence of other candidate genes in addition to BAP1 contributing to hereditary predisposition to UM.

Comprehensive review of BAP1 tumor predisposition syndrome with report of two new cases

The BRCA1‐associated protein‐1 (BAP1) tumor predisposition syndrome (BAP1‐TPDS) is a recently identified hereditary cancer syndrome. Germline mutations in this tumor suppressor gene predispose families to the development of various malignancies. The molecular functions of the gene as well as the clinical phenotype of the syndrome are still being clarified. We sought to conduct a comprehensive review of published research into BAP1‐TPDS to more thoroughly delineate the clinical implications of germline BAP1 mutations. We also report two additional families with germline BAP1 mutations. Current evidence demonstrates that germline BAP1 mutations predispose families to uveal melanoma, renal cell carcinoma, malignant mesothelioma, cutaneous melanoma, and possibly to a range of other cancers as well. Some of these cancers tend to be more aggressive, have a propensity to metastasize, and onset earlier in life in patients with BAP1 mutations as compared to non‐predisposed patients with equivalent cancers. Although further research is necessary, this information can aid in the management, diagnosis, and therapy of these patients and their families, and highlights the importance of genetic counseling.

Monosomy 3 status of uveal melanoma metastases is associated with rapidly progressive tumors and short survival.

The aim of the study was to investigate the molecular genetics of uveal melanoma (UM) metastases and correlate it with disease progression. Twelve pathologically confirmed UM metastases from 11 patients were included. Molecular genetic alterations in chromosomes 3 (including the BAP1 region), 8q, 6p, and 1p were investigated by microsatellite genotyping. Mutations in codon 209 of GNAQ and GNA11 genes were studied by restriction-fragment length polymorphism (RFLP). We identified monosomy of chromosome 3 in tumors from four patients with an average survival of 5 months (range 1-8 months) from time of diagnosis of metastatic disease. In contrast, tumors with either disomy or partial chromosome 3 alterations showed significantly slower metastatic disease progression with an average survival of 69 months (range 40-123 months, p = 0.003). Alterations in chromosomal arms 1p, 6p, and 8q and mutations in either GNAQ or GNA11 showed no association with disease progression. Prominent mononuclear inflammatory infiltrate was observed in tumors from patients with slowly progressive disease. In conclusion, in UM metastases, monosomy 3 is associated with highly aggressive, rapidly progressive disease while disomy or partial change of 3 and prominent mononuclear inflammatory infiltrate in the tumor is associated with better prognosis. These findings should be considered when designing clinical trials testing effectiveness of various therapies of metastatic UM.

Cancer family history characterization in an unselected cohort of 121 patients with uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. The extent of the contribution of familial/hereditary predisposition to the development of uveal melanoma is largely unknown. Thus we sought to ascertain the frequency of cancers in patients with UM and their family members to identify the prevalence of hereditary/familial predisposition to cancer in these patients. An unselected series of 121 patients with UM seen in a university-based tertiary referral program were consented to the study. Cancer histories (site and age of diagnosis) were obtained for all first- and second-degree relatives. Patients/families were classified as being potentially at high risk for hereditary predisposition if they met any of the following criteria: (1) Diagnosis of UM at age 30 or under, (2) Two or more cases of UM in the family, (3) UM plus at least one other primary cancer in the same patient (excluding non-melanoma skin and cervix cancers due to their strong environmental etiological link). (4) Family history meeting high risk criteria for a known hereditary cancer predisposition syndrome as defined by Hampel et al. (J Med Genet 41(2): 81–91, 2004). One patient had a family history of UM (0.8%). Ten patients (8.3%) had a personal and/or family history consistent with predisposition to a known hereditary cancer syndrome including six with possible hereditary breast, two with hereditary colon and two with hereditary melanomas. Twenty three patients (19%) had a personal history of a second cancer after exclusion of non-melanoma skin and cervical cancers. The frequency of cutaneous melanomas was significantly higher in UM patients than the general population (RR: 2.97, 95% CI: 1.00–6.94). Patients with a family history suggestive of a high risk predisposition to a known cancer syndrome had a significantly higher risk for having a second cancer than the remaining UM patients (Pxa0=xa00.02). Our results indicate that the frequency of UM patients with high risk for a hereditary cancer predisposition is much higher than earlier estimates (0.6%) and that it could be as high as 11.6%. Our results suggest that cancer phenotypes in these patients are diverse and include cancers other than UM. Thus, alerting ophthalmologists to the need for expanding their cancer family history intake to include other cancers is warranted. It also suggests that patients with a hereditary predisposition to UM have a higher risk for the development of other cancers and that characterization of the germline genetic alterations in these patients is highly warranted.

MET oncogene inhibition as a potential target of therapy for uveal melanomas.

PURPOSE. The purposes of this study were to investigate the frequency of MET activation in uveal melanomas (UMs), to study the potential molecular mechanism for its activation, and to assess the utility of MET inhibition as a potential therapy for UM. METHODS. The frequency of MET activation in UMs was studied by using immunohistochemistry and Western blot analysis in 46 primary UMs and six UM cell lines. Sequencing was used for detection of activating mutations in the MET gene, and the effect of selective MET inhibition was assessed by cell proliferation and migration assays. RESULTS. The results showed that the majority (82.5%) of the 46 UMs expressed activated MET protein. Three of the UM cell lines, C918, 92.1, and MEL202, showed strong MET and pMET expression, whereas the other three showed weaker expression. Sequence analysis identified no activating mutations in MET in any of the 22 tumors or in the six UM cell lines. Selective MET blocking showed inhibition of tumor cell proliferation at an IC(50) ranging from 2.5 to 5.2 microM. A significant inhibition of UM cell migration was also observed starting at 1.25 microM. CONCLUSIONS. The results indicate that MET is activated in a significant number of UMs and also that MET activation in UMs is most likely through indirect gene activation rather than copy number alteration or mutation involving the MET gene. MET inhibition could be a target of therapy for UM.

Frequency, molecular pathology and potential clinical significance of partial chromosome 3 aberrations in uveal melanoma

The clinical significance of partial chromosome 3 alteration in uveal melanoma is still not clear. Also, the reported frequencies vary considerably in the published literature from 0 to 48%. The aims of the following study were to identify the frequency, molecular pathology and potential clinical significance of partial chromosome 3 alteration in uveal melanoma. We studied 47 uveal melanomas with an average follow-up of 36 months. Of these, 14 had confirmed metastasis. Allelic imbalance/loss of heterozygosity was studied using microsatellite markers on chromosome 3 enriched in markers located in the previously reported smallest regions of deletion overlap. Chromosomal alterations were assessed by conventional cytogenetics or comparative genomic hybridization (CGH) in a subset of patients. Utilizing genotyping, partial chromosome 3 alteration was detected in 14/47 tumors (30%). In the 23 tumors with available cytogenetic/CGH, partial chromosome 3 alteration was detected in 8/23 (38%) and was caused by both gains (4/8) and losses (4/8) of chromosome 3 with high frequency of complex chromosome 3 aberrations detected by cytogenetics. Out of the 14 tumors with confirmed metastasis, only 1 showed partial chromosome 3 alteration and the remaining showed monosomy 3. By limiting the aggressive disease marker to monosomy 3, genotyping showed 93% sensitivity and 67% specificity for detection of aggressive uveal melanoma. In conclusion, partial chromosome 3 alterations are common in uveal melanoma and mostly caused by complex cytogenetic changes leading to partial gains and/or partial losses of chromosome 3. Partial chromosome 3 alteration is not likely to be associated with highly aggressive uveal melanoma that metastasizes within the first 3 years after treatment. Microsatellite-based genotyping of chromosome 3 is highly sensitive for detection of aggressive uveal melanoma.

Analysis of BAP1 Germline Gene Mutation in Young Uveal Melanoma Patients

Abstract Background: To evaluate the prevalence of BAP1 germline mutations in a series of young patients with uveal melanoma (UM), diagnosed before age 30. Materials and Methods: The study was carried out on 14 young uveal melanoma patients (average age 21.4 years, range 3 months to 29 years). Germline DNA was extracted from peripheral blood. BAP1 sequencing was carried out using direct sequencing of all exons and adjacent intronic sequences. We also tested for germline mutations in additional melanoma-associated candidate genes CDKN2A and CDK4 (exon 4). Results: We identified one patient with a pathogenic mutation (c. 1717delC, p.L573fs*3) in BAP1. This patient was diagnosed with UM at age 18 years and had a family history of a father with UM and a paternal grandfather with cancer of unknown origin. One additional patient had an intronic variant of uncertain significance (c.123-48Tu2009>u2009G) in BAP1 while the remaining 12 patients had no alteration. None of the patients had CDKN2A or CDK4 (Exon 4) mutations. Family history was positive for a number of additional malignancies in this series, in particular for cutaneous melanoma, prostate, breast and colon cancers. There were no families with a history of mesothelioma or renal cell carcinoma. Conclusions: This study suggests that a small subset of patients with early onset UM has germline mutation in BAP1. While young patients with UM should be screened for germline BAP1 mutations, our results suggest that there is a need to identify other candidate genes which are responsible for UM in young patients.

In vitro anti-uveal melanoma activity of phenolic compounds from the Egyptian medicinal plant Acacia nilotica

Anti-uveal melanoma activity-guided fractionation of the MeOH extract of Acacia nilotica pods resulted in the isolation of the new compound gallocatechin 5-O-gallate in addition to methyl gallate, gallic acid, catechin, catechin 5-O-gallate, 1-O-galloyl-β-D-glucose, 1,6-di-O-galloyl-β-D-glucose and digallic acid. The structures of the isolated compounds were elucidated on the basis of HRESIMS, NMR spectroscopy and CD data. In addition to uveal melanoma, the antiproliferative activities of the isolated compounds and the related compound epigallocatechin 3-O-gallate (EGCG) were evaluated against cutaneous melanoma, ovarian cancer, glioblastoma and normal retinal pigmented cells.