Somatic Mutation In GNAQ Research Articles

Investigation of Somatic GNAQ, GNA11, BAP1 and SF3B1 Mutations in Ophthalmic Melanocytomas

Purpose: The aim of this study was to use massively parallel DNA sequencing to identify GNAQ/11, BAP1 and SF3B1 mutations in ophthalmic melanocytoma. Procedures: Six ophthalmic melanocytoma specimens (1 iridociliary and 5 optic nerve) were profiled for genomic alterations in GNAQ/11, BAP1 and SF3B1 using a custom deep sequencing assay. This assay uses solution phase hybridization-based exon capture and deep-coverage massively parallel DNA sequencing to interrogate all protein-coding exons and select introns. Results: The only iridociliary melanocytoma showed a mutation in GNAQ but not in BAP1. Of the 2 optic-nerve melanocytomas that developed into melanoma, one had a GNAQ mutation and both a BAP1 mutation and monosomy 3. The remaining 3 optic-nerve melanocytomas did not reveal mutations in GNAQ/11 or BAP1. SF3B1 mutations were not detected in any specimen. Conclusions: The presence of GNAQ mutation in some iridociliary and optic-nerve melanocytomas suggests a possible relationship between ophthalmic melanocytoma and other ophthalmic melanocytic neoplasms. BAP1 mutation may accompany the transformation of ophthalmic melanocytoma to melanoma.

The somatic GNAQ mutation (R183Q) is primarily located within the blood vessels of port wine stains

Author(s): Tan, Wenbin; Nadora, Dawnica Mercado; Gao, Lin; Wang, Gang; Mihm, Martin C; Nelson, J Stuart

Melanomas Associated With Blue Nevi or Mimicking Cellular Blue Nevi: Clinical, Pathologic, and Molecular Study of 11 Cases Displaying a High Frequency of GNA11 Mutations, BAP1 Expression Loss, and a Predilection for the Scalp.

Melanomas associated with blue nevi (MABN) or mimicking cellular blue nevi (MMCBN) represent exceptional variants of malignant cutaneous melanocytic tumors. Uveal and leptomeningeal melanomas frequently have somatic mutations of GNAQ or GNA11, which are believed to be early driver mutations. In uveal melanomas, monosomy 3, linked to the BAP1 gene, is an adverse prognostic factor. We have studied the clinical, histologic, BAP1 expression profile, and molecular data of 11 cases of MABN/MMCBN and 24 cellular blue nevi. Most of the cases of MABN/MMCBN occurred on the scalps of adult patients and presented as rapidly growing nodules, typically >1 cm, often arising at the site of a preexisting melanocytic lesion. The MABN/MMCBN were composed of dense nests of large dermal atypical melanocytes, in some cases lying adjacent to a blue nevus. Four patients developed metastatic disease, and 2 died from their disease. A GNA11 mutation was found in 8/11 cases and a GNAQ mutation in 1 case. Seven of 11 cases showed loss of nuclear BAP1 immunohistochemical (IHC) expression in the malignant component, sparing the adjacent nevus. Array comparative genomic hybridization revealed recurrent deletions of chromosomes 1p, 3p, 4q, 6q, 8p, 16q, and 17q and recurrent gains of chromosomes 6p, 8q, and 21q. The 24 cases of cellular blue nevi frequently occurred on the sacrum, had GNAQ mutations, and showed normal positive IHC staining for BAP1. These results underscore overlapping features in all blue-like malignant melanocytic tumors. Loss of BAP1 IHC expression was restricted to melanomas, including all metastatic cases.

Endothelial Cells from Capillary Malformations Are Enriched for Somatic GNAQ Mutations.

A somatic mutation in GNAQ (c.548G>A; p.R183Q), encoding Gαq, has been found in syndromic and sporadic capillary malformation tissue. However, the specific cell type containing the mutation is unknown. The purpose of this study was to determine which cells in capillary malformations have the GNAQ mutation. Human capillary malformation tissue was obtained from 13 patients during a clinically indicated procedure. Droplet digital polymerase chain reaction, capable of detecting mutant allelic frequencies as low as 0.1 percent, was used to quantify the abundance of GNAQ mutant cells in capillary malformation tissue. Six specimens were fractionated by fluorescence-activated cell sorting into hematopoietic, endothelial, perivascular, and stromal cells. The frequency of GNAQ mutant cells in these populations was quantified by droplet digital polymerase chain reaction. Eight capillary malformations contained GNAQ p.R183Q mutant cells, two lesions had novel GNAQ mutations (p.R183L and p.R183G), and three capillary malformations did not have a detectable GNAQ p.R183 mutation. Mutant allelic frequencies ranged from 2 to 11 percent. Following fluorescence-activated cell sorting, the GNAQ mutation was found in the endothelial but not the platelet-derived growth factor receptor-β-positive cell population; mutant allelic frequencies were 3 to 43 percent. Endothelial cells in capillary malformations are enriched for GNAQ mutations and are likely responsible for the pathophysiology underlying capillary malformation.

English

The Sturge-Weber syndrome is a sporadic congenital neurocutaneous disorder with port- wine stain affecting the facial skin in the distribution of the ophthalmic branch of the trigeminal nerve, abnormal capillary venous vessels in the leptomeninges of the brain and choroid resulting in glaucoma, seizures, stroke and intellectual disability. (1) Sturge-Weber syndrome and port-wine stains are believed to be caused by Somatic Mutation in GNAQ. (2) We present a case of 18 years old patient of SWS for its rarity of occurrance and the difficulties posed in the management of this condition. The aim of this article is to stress the importance of this condition that may be overlooked in the diagnosis.

Constitutive activation of the ERK pathway in melanoma and skin melanocytes in Grey horses.

BackgroundConstitutive activation of the ERK pathway, occurring in the vast majority of melanocytic neoplasms, has a pivotal role in melanoma development. Different mechanisms underlie this activation in different tumour settings. The Grey phenotype in horses, caused by a 4.6 kb duplication in intron 6 of Syntaxin 17 (STX17), is associated with a very high incidence of cutaneous melanoma, but the molecular mechanism behind the melanomagenesis remains unknown. Here, we investigated the involvement of the ERK pathway in melanoma development in Grey horses.MethodsGrey horse melanoma tumours, cell lines and normal skin melanocytes were analyzed with help of indirect immunofluorescence and immunoblotting for the expression of phospho-ERK1/2 in comparison to that in non-grey horse and human counterparts. The mutational status of BRAF, RAS, GNAQ, GNA11 and KIT genes in Grey horse melanomas was determined by direct sequencing. The effect of RAS, RAF and PI3K/AKT pathways on the activation of the ERK signaling in Grey horse melanoma cells was investigated with help of specific inhibitors and immunoblotting. Individual roles of RAF and RAS kinases on the ERK activation were examined using si-RNA based approach and immunoblotting.ResultsWe found that the ERK pathway is constitutively activated in Grey horse melanoma tumours and cell lines in the absence of somatic activating mutations in BRAF, RAS, GNAQ, GNA11 and KIT genes or alterations in the expression of the main components of the pathway. The pathway is mitogenic and is mediated by BRAF, CRAF and KRAS kinases. Importantly, we found high activation of the ERK pathway also in epidermal melanocytes, suggesting a general predisposition to melanomagenesis in these horses.ConclusionsThese findings demonstrate that the presence of the intronic 4.6 kb duplication in STX17 is strongly associated with constitutive activation of the ERK pathway in melanocytic cells in Grey horses in the absence of somatic mutations commonly linked to the activation of this pathway during melanomagenesis. These findings are consistent with the universal importance of the ERK pathway in melanomagenesis and may have valuable implications for human melanoma research.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-857) contains supplementary material, which is available to authorized users.

The somatic GNAQ mutation c.548G>A (p.R183Q) is consistently found in Sturge-Weber syndrome.

Sturge-Weber syndrome (SWS) is a neurocutaneous disorder characterized by capillary malformation (port-wine stains), and choroidal and leptomeningeal vascular malformations. Previously, the recurrent somatic mutation c.548G>A (p.R183Q) in the G-α q gene (GNAQ) was identified as causative in SWS and non-syndromic port-wine stain patients using whole-genome sequencing. In this study, we investigated somatic mutations in GNAQ by next-generation sequencing. We first performed targeted amplicon sequencing of 15 blood-brain-paired samples in sporadic SWS and identified the recurrent somatic c.548G>A mutation in 80% of patients (12 of 15). The percentage of mutant alleles in brain tissues of these 12 patients ranged from 3.6 to 8.9%. We found no other somatic mutations in any of the seven GNAQ exons in the remaining three patients without c.548G>A. These findings suggest that the recurrent somatic GNAQ mutation c.548G>A is the major determinant genetic factor for SWS and imply that other mutated candidate gene(s) may exist in SWS.

Chromosome 3 status combined with BAP1 and EIF1AX mutation profiles are associated with metastasis in uveal melanoma.

Somatic mutations in GNAQ, GNA11, SF3B1, EIF1AX, and BAP1 have been identified in uveal melanoma (UM). The aim of this study was to determine whether mutations in these genes in primary tumors were associated with metastases in individuals diagnosed with UM. A total of 63 UM cases who developed a metastasis within 48 months of primary treatment and 53 UM controls who were metastasis-free over a similar time period were selected for the study. Primary UM cases were screened for mutations in GNAQ, GNA11, SF3B1, EIF1AX, and BAP1. The association of these mutations with tumor characteristics, chromosome 3 copy number, and metastatic status was analyzed by logistic regression to estimate the odds of developing metastasis within 48 months. As expected, tumor diameter, thickness, cilio-choroidal location, and chromosome 3 monosomy were all significantly (P < 0.02) associated with the presence of metastasis. In univariate analysis, GNA11 (odds ratio [OR] 2.5, 95% confidence interval [CI] 1.1-5.5) and BAP1 (OR 6.3, 95% CI 2.7-14.4) mutations were positively associated and EIF1AX mutation (OR 0.13, 95% CI 0.034-0.47) was inversely associated with metastatic status at 48 months after UM treatment. After adjustment for covariates, a chromosome 3 monosomy/BAP1-mutation/EIF1AX-wild-type (WT) mutation profile was strongly associated (OR 37.5, 95% CI 4.3-414) with the presence of metastasis compared with a chromosome 3 disomy/BAP1-WT/EIF1AX mutation profile. The results suggest that knowledge of mutations in BAP1 and EIF1AX can enhance prognostication of UM beyond that determined by chromosome 3 and tumor characteristics. Tumors with chromosome 3 disomy/BAP1-WT/EIF1AX-WT have a 10-fold increased risk of metastasis at 48 months compared with disomy-3/BAP1-WT/EIF1AX mutant tumors.

Ocular melanoma and the BAP1 hereditary cancer syndrome: implications for the dermatologist

Ocular melanoma is a rare subtype of melanoma, which includes uveal melanoma (UM) and conjunctival melanoma. UM is associated with an increased risk of cutaneous melanoma (CM) in addition to mesothelioma, skin lesions such as epithelioid atypical Spitz tumors, and other internal malignancies due to a germline mutation of the BRCA1-associated protein 1 (BAP1) gene. Such familial risks are important for dermatologists to recognize when screening patients with a history of UM for CM and other malignancies. Molecular genetics further help to elucidate the connections between UM and CM by revealing similarities and differences in important mutations among the melanoma subtypes. Both UM and CM have been shown to harbor germline mutation of BAP1. However, somatic mutations in either GNAQ or GNA11 are unique to UM tumors and could be used as potential markers to differentiate UM from metastatic CM and act as direct therapeutic targets. However, CM-associated BRAF and CDKN2A mutations are rare in UM. This review addresses the clinical features, pathogenesis, and current treatment options of UM, focusing on UM and the BAP1 cancer syndrome to raise awareness of ocular melanoma and its greater role in the predisposition to a hereditary cancer syndrome.

Deciphering root causes of intrinsic BRAF inhibitor resistance in melanoma: ushering in a new genomics case reports feature for Annals of Oncology

Deciphering root causes of intrinsic BRAF inhibitor resistance in melanoma: ushering in a new genomics case reports feature for Annals of Oncology

Single-cell analysis: toward the clinic.

Single-cell analysis: toward the clinic.

Somatic GNAQ mutation

Somatic GNAQ mutation

Sturge–Weber Syndrome and Port-Wine Stains Caused by Somatic Mutation in GNAQ

BackgroundThe Sturge–Weber syndrome is a sporadic congenital neurocutaneous disorder characterized by a port-wine stain affecting the skin in the distribution of the ophthalmic branch of the trigeminal nerve, abnormal capillary venous vessels in the leptomeninges of the brain and choroid, glaucoma, seizures, stroke, and intellectual disability. It has been hypothesized that somatic mosaic mutations disrupting vascular development cause both the Sturge–Weber syndrome and port-wine stains, and the severity and extent of presentation are determined by the developmental time point at which the mutations occurred. To date, no such mutation has been identified.MethodsWe performed whole-genome sequencing of DNA from paired samples of visibly affected and normal tissue from 3 persons with the Sturge–Weber syndrome. We tested for the presence of a somatic mosaic mutation in 97 samples from 50 persons with the Sturge–Weber syndrome, a port-wine stain, or neither (controls), using amplicon sequencing and SNaPshot assays, and investigated the effects of the mutation on downstream signaling, using phosphorylation-specific antibodies for relevant effectors and a luciferase reporter assay.ResultsWe identified a nonsynonymous single-nucleotide variant (c.548G→A, p.Arg183Gln) in GNAQ in samples of affected tissue from 88% of the participants (23 of 26) with the Sturge–Weber syndrome and from 92% of the participants (12 of 13) with apparently nonsyndromic port-wine stains, but not in any of the samples of affected tissue from 4 participants with an unrelated cerebrovascular malformation or in any of the samples from the 6 controls. The prevalence of the mutant allele in affected tissues ranged from 1.0 to 18.1%. Extracellular signal-regulated kinase activity was modestly increased during transgenic expression of mutant Gαq.ConclusionsThe Sturge–Weber syndrome and port-wine stains are caused by a somatic activating mutation in GNAQ. This finding confirms a long-standing hypothesis. (Funded by the National Institutes of Health and Hunter's Dream for a Cure Foundation.)

Immunohistochemical and molecular pathology of ocular uveal melanocytoma: evidence for somatic GNAQ mutations

ObjectiveIntraocular melanocytoma is a rare naevus variant that can be located at the optic disc or within the uvea, and belongs to the group of non-epithelial-associated melanocytic lesions. We wanted...

Current advances and perspectives in the treatment of advanced melanoma

Melanoma has long been considered as an extremely therapy-resistant tumour. Recent developments in the area of immunotherapy as well as targeted therapy showed rapid development and excellent results. The anti-CTLA-4 antibody ipilimumab, which was approved in the USA and Europe in 2011, was the first substance in melanoma therapy to demonstrate an overall survival benefit. Another approval is expected in Europe for the specific BRAF-inhibitor vemurafenib, which has shown a significant impact on progression-free survival and overall survival in patients with the BRAF(V600E) mutation. In this review the relevant agents in the substance classes of immunomodulatory drugs and small molecules are presented and discussed, and future prospects for combination therapies and developments in melanoma treatment are outlined.

Molecular genetic testing of uveal melanoma from routinely processed and stained cytology specimens

In the following study we investigated the utility of molecular genetic testing of the DNA extracted from routinely stained and processed smears from uveal melanoma (UM). Smears from five uveal melanoma cell lines and 12 primary tumors were prepared and stained with Papanicolaou and Romanowsky stains. Genotyping was carried out utilizing 14 microsatellite markers on chromosomes 3, 6 and 8. Mutational screening for alterations in GNAQ and GNA11 genes was carried out by restriction fragment length polymorphism. The results were compared to those obtained through direct sequencing of frozen tumor tissues. High quality DNA was extracted from the stained slides with no difference in the efficiency of DNA extraction between the two staining techniques. The extracted DNA was of adequate quality for genotyping and mutational screening. DNA extracted from approximately 200 tumor cells is sufficient for reproducible testing of allelic imbalances and for studying the common somatic mutations in GNAQ and GNA11 genes. In conclusion, we presented the feasibility of utilizing routinely stained cytology smears from UM for molecular genetic testing. The DNA obtained is of sufficient quality to carry out genotyping for markers on chromosome 3, 6 and 8, as well as screening for somatic mutations in GNAQ and GNA11 genes.

Abstract 1127: Lack of MAPK activation in significant number of uveal melanomas with somatic mutation in GNAQ and GNA11

Abstract Purpose: The aims of this study were to investigate the correlation between MAPK activation and somatic mutation in GNAQ and GNA11 genes in uveal melanoma (UM) and to investigate the potential utility of MEK inhibition as a target for therapy of UM in tumors with GNAQ and GNA11 mutations. Methods: Sequencing and restriction fragment length polymorphism (RFLP) were utilized for detection of activating mutations in codon 209 of the GNAQ and GNA11 genes in 44 primary UMs. The expression of phospho p44/42 MAPK (pERK1/2) was assessed by immunohistochemistry in 44 UMs. In addition, the expression of pERK1/2 and pMEK 1/2 were studied using Western blot analysis in 17 primary UMs (14 with GNAQ or GNA11 mutations) and five UM cell lines (C918, 92.1, OCM3, MEL202, MEL270). Three of the UM cell lines (92.1, MEL202 and MEL270) have GNAQ codon 209 mutations. The effect of three different selective MEK inhibitors (U126, PD98059 and PD184352) on UM cell proliferation and apoptosis were studied. Results: The majority (30/44, 68.2%) of the primary UM tumors showed somatic mutation in codon 209 of either the GNAQ or the GNA11 genes. With the exception of one tumor, the mutations in either gene were mutually exclusive. Of the 30 UM primary tumors with GNAQ and/or GNA11 mutation, pERK1/2 expression was absent in 26.7%, weak in 33.3%, moderate in 23.3%, and high in only 16.7%. Western blot showed no pMEK1/2 expression in 6/14 (42.9%) of UM with either GNAQ or GNA11 mutations. Two of the UM cell lines with GNAQ mutation showed weak pERK1/2 expression. In addition one showed no pMEK1/2 expression while the other one showed very weak pMEK1/2 expression. Selective MEK inhibitors slowed UM cell proliferation but didn't induce significant apoptosis in UM cell lines regardless of GNAQ status. Conclusions: Our results indicate that a significant number of UM with somatic mutations in GNAQ or GNA11 showed no MAPK pathway activation. In UM, MEK inhibition is mostly cytostatic suggesting that selective MEK inhibitors alone may not be sufficient to control UM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1127. doi:10.1158/1538-7445.AM2011-1127

Mutations inGNA11in Uveal Melanoma

Uveal melanoma is the most common intraocular cancer. There are no effective therapies for metastatic disease. Mutations in GNAQ, the gene encoding an alpha subunit of heterotrimeric G proteins, are found in 40% of uveal melanomas. We sequenced exon 5 of GNAQ and GNA11, a paralogue of GNAQ, in 713 melanocytic neoplasms of different types (186 uveal melanomas, 139 blue nevi, 106 other nevi, and 282 other melanomas). We sequenced exon 4 of GNAQ and GNA11 in 453 of these samples and in all coding exons of GNAQ and GNA11 in 97 uveal melanomas and 45 blue nevi. We found somatic mutations in exon 5 (affecting Q209) and in exon 4 (affecting R183) in both GNA11 and GNAQ, in a mutually exclusive pattern. Mutations affecting Q209 in GNA11 were present in 7% of blue nevi, 32% of primary uveal melanomas, and 57% of uveal melanoma metastases. In contrast, we observed Q209 mutations in GNAQ in 55% of blue nevi, 45% of uveal melanomas, and 22% of uveal melanoma metastases. Mutations affecting R183 in either GNAQ or GNA11 were less prevalent (2% of blue nevi and 6% of uveal melanomas) than the Q209 mutations. Mutations in GNA11 induced spontaneously metastasizing tumors in a mouse model and activated the mitogen-activated protein kinase pathway. Of the uveal melanomas we analyzed, 83% had somatic mutations in GNAQ or GNA11. Constitutive activation of the pathway involving these two genes appears to be a major contributor to the development of uveal melanoma. (Funded by the National Institutes of Health and others.).

Lack of GNAQ germline mutations in uveal melanoma patients with high risk for hereditary cancer predisposition

A high frequency of somatic mutation in GNAQ has been reported in uveal melanoma (UM). GNAQ is located in the chromosomal band 9q21, the same chromosomal band that harbors a putative candidate gene for hereditary UM. We investigated the frequency of germline sequence alterations in the GNAQ gene in UM patients with increased predisposition to hereditary cancer. A total of 44 high risk UM patients were studied including three patients with a family history of UM, 15 patients with a family history of cutaneous melanoma (CM), three patients with early age at onset of their UM (<30years) and 23 patients with strong family history of cancer and/or personal history of multiple primary tumors. Mutational screening of the seven exons of GNAQ and nearby intronic sequence was carried out by direct sequencing. We identified two deep intronic variants but no potential pathogenic mutations in GNAQ. Our results exclude GNAQ as a candidate gene in UM patients with a high risk for hereditary cancer predisposition.

Somatic mutations in GNAQ in amelanotic/hypomelanotic blue nevi

A recent study indicates that somatic mutations in codon 209 of GNAQ, a gene encoding the signaling protein G-protein α subunit q, may be present in up to 80% of blue nevi. Given that mutations in GNAQ represent dominant dark skin (Dsk) mutations caused by increased dermal melanin, the primary aim of this study was to ascertain whether amelanotic/hypomelanotic blue nevi exhibited somatic mutations in GNAQ like their melanotic counterpart. Genomic DNA was isolated for genotyping per protocol using techniques including laser capture microdissection to isolate nevus cells from amelanotic/hypomelanotic blue nevi (n = 8). The positive control group comprised regular blue nevi (n = 10, all melanotic) and cellular blue nevi (n = 9, all melanotic), whereas the negative control group comprised other dermal-based nevomelanocytic proliferations such as intradermal melanocytic nevi (n = 9, 7 of which were amelanotic) and metastatic melanoma (n = 9, 5 of which were amelanotic). DNA sequencing analysis was performed on GNAQ spanning codon 209, BRAFV600E, NRAS1, NRAS2, and KRAS genes. Mutations in GNAQ were noted in 12.5% (1/8) of amelanotic/hypomelanotic blue nevi. In the control group 40% (4/10) of blue nevi and 44% (4/9) of cellular blue nevi demonstrated the GNAQ mutation, with no cases of metastatic melanoma or intradermal melanocytic nevi exhibiting the mutation. All GNAQ mutations were A/T point mutations, and statistically significant differences were not noted among the amelanotic/hypomelanotic blue nevi, blue nevi, and cellular blue nevi subgroups. Although additional mutations were not noted in cases of amelanotic/hypomelanotic blue nevi, one blue nevus exhibited a mutation in KRAS alone; one cellular blue nevus, a concurrent NRAS2 mutation; one cellular blue nevus, a concurrent KRAS mutation; and a third cellular blue nevus, a mutation in KRAS alone. The presence of GNAQ mutations in the amelanotic/hypomelanotic blue nevus indicates that mechanisms underlying pigment homeostasis in this variant appear to be similar to those of its melanotic counterparts, although it is not clear why activation of the q class of the G-protein α subunit should cause an abundance of dermal pigment in one variant and not in another. Given that dermal melanocytes are present since birth, one possible explanation is that their melanin-synthesizing pathway is usually in a dormant state. Activation of this pathway is a consequence of multiple triggers-one of which is a mutation in the GNAQ gene, whereas the other is yet to be identified.