RESUMO
Protein kinase A (PKA) hyperactivation causes hereditary endocrine neoplasias; however, its role in sporadic epithelial cancers is unknown. Here, we show that heightened PKA activity in the mammary epithelium generates tumors. Mammary-restricted biallelic ablation of Prkar1a, which encodes for the critical type-I PKA regulatory subunit, induced spontaneous breast tumors characterized by enhanced type-II PKA activity. Downstream of this, Src phosphorylation occurs at residues serine-17 and tyrosine-416 and mammary cell transformation is driven through a mechanism involving Src signaling. The phenotypic consequences of these alterations consisted of increased cell proliferation and, accordingly, expansion of both luminal and basal epithelial cell populations. In human breast cancer, low PRKAR1A/high SRC expression defines basal-like and HER2 breast tumors associated with poor clinical outcome. Together, the results of this study define a novel molecular mechanism altered in breast carcinogenesis and highlight the potential strategy of inhibiting SRC signaling in treating this cancer subtype in humans.
Assuntos
Transformação Celular Neoplásica/metabolismo , Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico/metabolismo , Glândulas Mamárias Animais/patologia , Neoplasias Mamárias Experimentais/patologia , Quinases da Família src/metabolismo , Androstadienos/farmacologia , Animais , Linhagem Celular , Proliferação de Células , Transformação Celular Neoplásica/patologia , Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico/genética , Dasatinibe , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Feminino , Humanos , Glândulas Mamárias Animais/metabolismo , Neoplasias Mamárias Experimentais/metabolismo , Camundongos , Fosforilação , Pirimidinas/farmacologia , Transdução de Sinais , Tiazóis/farmacologia , Wortmanina , Quinases da Família src/genéticaRESUMO
Schwannomas are peripheral nerve sheath tumors that often occur in the setting of an inherited tumor predisposition syndrome, including neurofibromatosis types 1 (NF1) and 2 (NF2), familial schwannomatosis and Carney complex. Loss of the NF2 tumor suppressor (encoding NF2, or Merlin) is associated with upregulation of the Rac1 small GTPase, which is thought to have a key role in mediating tumor formation. In prior studies, we generated a mouse model of schwannomas by performing tissue-specific knockout (KO) of the Carney complex gene Prkar1a, which encodes the type 1A regulatory subunit of protein kinase A. These tumors exhibited down-regulation of Nf2 protein and an increase in activated Rac1. To assess the requirement for Rac1 in schwannoma formation, we generated a double KO (DKO) of Prkar1a and Rac1 in Schwann cells and monitored tumor formation. Loss of Rac1 reduced tumor formation by reducing proliferation and enhancing apoptosis. Surprisingly, the reduction of tumor formation was accompanied by re-expression of the Nf2 protein. Furthermore, activated Rac1 was able to downregulate Nf2 in vitro in a Pak-dependent manner. These in vivo data indicate that activation of Rac1 is responsible for suppression of Nf2 protein production; deficiency of Nf2 in Schwann cells leads to loss of cellular growth control and tumor formation. Further, PKA activation through mutation in Prkar1a is sufficient to initiate Rac1 signaling, with subsequent reduction of Nf2 and schwannomagenesis. Although in vitro evidence has shown that loss of Nf2 activates Rac1, our data indicate that signaling between Nf2 and Rac1 occurs in a bidirectional fashion, and these interactions are modulated by PKA.
Assuntos
Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico/fisiologia , Genes da Neurofibromatose 2 , Neurilemoma/genética , Neuropeptídeos/fisiologia , Proteínas rac de Ligação ao GTP/fisiologia , Animais , Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico/genética , Regulação para Baixo/genética , Camundongos , Camundongos Knockout , Neurilemoma/patologia , Neuropeptídeos/genética , Células de Schwann/patologia , Proteínas rac de Ligação ao GTP/genética , Proteínas rac1 de Ligação ao GTPRESUMO
Carney complex (CNC) is an autosomal dominant, multiple endocrine neoplasia syndrome comprised of spotty skin pigmentation, myxomatosis, endocrine tumours and schwannomas. The majority of cases are due to inactivating mutations in PRKAR1A, the gene encoding the type 1A regulatory subunit of the 3',5'-cyclic adenosine monophosphate (cAMP)-dependent protein kinase, PKA (protein kinase A). In order to understand the molecular basis for tumorigenesis associated with PRKAR1A mutations, we have developed conventional and conditional Prkar1a knockout (KO) mice as well as primary cell culture models corresponding to these genetic manipulations. At the biochemical level, removal of Prkar1a from cells causes enhanced PKA activity, the same effect which has been observed in tumours isolated from CNC patients. Mice heterozygous for Prkar1a mutations (the exact genetic model for CNC patients) are born at expected frequencies and are tumour prone, developing neoplasms in cAMP-responsive cell types such as Schwann cells, osteoblasts and thyrocytes. In order to understand the basis of tissue-specific tumour formation, we have created tissue-specific KOs of the gene from three different tissues: the neural crest (Schwann cells), the pituitary gland and the heart. In the neural crest and the pituitary, ablation of Prkar1a leads to excess proliferation and tumorigenesis, whereas the same manipulation in developing cardiomyocytes leads to reduced proliferation and embryonic demise. The KO hearts also exhibit myxomatous changes suggesting a connection between PKA activation and myxomagenesis, although the nature of this relationship has not yet been determined. This work confirms the role of Prkar1a as a tissue-specific tumour suppressor, and ongoing work is focused on identifying the key downstream signalling targets affected by dysregulation of PKA.
Assuntos
Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico/genética , Modelos Animais de Doenças , Neoplasia Endócrina Múltipla/genética , Animais , Transformação Celular Neoplásica/genética , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Camundongos , Camundongos Knockout , MutaçãoRESUMO
BACKGROUND: Inactivation of the human type Ialpha regulatory subunit (RIalpha) of cyclic AMP dependent protein kinase (PKA) (PRKAR1A) leads to altered kinase activity, primary pigmented nodular adrenocortical disease (PPNAD), and sporadic adrenal and other tumours. METHODS AND RESULTS: A transgenic mouse carrying an antisense transgene for Prkar1a exon 2 (X2AS) under the control of a tetracycline responsive promoter (the Tg(Prkar1a*x2as)1Stra, Tg(tTAhCMV)3Uh or tTA/X2AS line) developed thyroid follicular hyperplasia and adenomas, adrenocortical hyperplasia and other features reminiscent of PPNAD, including late onset weight gain, visceral adiposity, and non-dexamethasone suppressible hypercorticosteronaemia, with histiocytic, epithelial hyperplasias, lymphomas, and other mesenchymal tumours. These lesions were associated with allelic losses of the mouse chromosome 11 Prkar1a locus, an increase in total type II PKA activity, and higher RIIbeta protein levels; the latter biochemical and protein changes were also documented in Carney complex tumours associated with PRKAR1A inactivating mutations and chromosome 17 PRKAR1A locus changes. CONCLUSION: We conclude that the tTA/X2AS mouse line with a downregulated Prkar1a gene replicates several of the findings in Carney complex patients and their affected tissues, supporting the role of RIalpha as a candidate tumour suppressor gene.
Assuntos
Neoplasias das Glândulas Endócrinas/enzimologia , Proteínas/fisiologia , Doenças do Córtex Suprarrenal/enzimologia , Doenças do Córtex Suprarrenal/genética , Neoplasias das Glândulas Suprarrenais/enzimologia , Neoplasias das Glândulas Suprarrenais/genética , Alelos , Animais , Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico , Proteína Quinase Tipo II Dependente de AMP Cíclico , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Regulação para Baixo , Neoplasias das Glândulas Endócrinas/genética , Deleção de Genes , Genes Supressores de Tumor , Humanos , Perda de Heterozigosidade , Camundongos , Camundongos Transgênicos , Mutação , Síndromes Neoplásicas Hereditárias/enzimologia , Síndromes Neoplásicas Hereditárias/genética , Fenótipo , Proteínas/genética , Neoplasias da Glândula Tireoide/enzimologia , Neoplasias da Glândula Tireoide/genéticaRESUMO
Carney complex (CNC) is an autosomal dominant multiple endocrine neoplasia and lentiginosis syndrome characterised by spotty skin pigmentation, cardiac, skin, and breast myxomas, and a variety of endocrine and other tumours. The disease is genetically heterogeneous; two loci have been mapped to chromosomes 17q22-24 (the CNC1 locus) and 2p16 (CNC2). Mutations in the PRKAR1A tumour suppressor gene were recently found in CNC1 mapping kindreds, while the CNC2 and perhaps other genes remain unidentified. Analysis of tumour chromosome rearrangements is a useful tool for uncovering genes with a role in tumorigenesis and/or tumour progression. CGH analysis showed a low level 2p amplification recurrently in four of eight CNC tumours; one tumour showed specific amplification of the 2p16-p23 region only. To define more precisely the 2p amplicon in these and other tumours, we completed the genomic mapping of the CNC2 region, and analysed 46 tumour samples from CNC patients with and without PRKAR1A mutations by fluorescence in situ hybridisation (FISH) using bacterial artificial chromosomes (BACs). Consistent cytogenetic changes of the region were detected in 40 (87%) of the samples analysed. Twenty-four samples (60%) showed amplification of the region represented as homogeneously stained regions (HSRs). The size of the amplicon varied from case to case, and frequently from cell to cell in the same tumour. Three tumours (8%) showed both amplification and deletion of the region in their cells. Thirteen tumours (32%) showed deletions only. These molecular cytogenetic changes included the region that is covered by BACs 400-P-14 and 514-O-11 and, in the genetic map, corresponds to an area flanked by polymorphic markers D2S2251 and D2S2292; other BACs on the centromeric and telomeric end of this region were included in varying degrees. We conclude that cytogenetic changes of the 2p16 chromosomal region that harbours the CNC2 locus are frequently observed in tumours from CNC patients, including those with germline, inactivating PRKAR1A mutations. These changes are mostly amplifications of the 2p16 region, that overlap with a previously identified amplicon in sporadic thyroid cancer, and an area often deleted in sporadic adrenal tumours. Both thyroid and adrenal tumours constitute part of CNC indicating that the responsible gene(s) in this area may indeed be involved in both inherited and sporadic endocrine tumour pathogenesis and/or progression.
Assuntos
Anormalidades Múltiplas/genética , Aberrações Cromossômicas , Cromossomos Humanos Par 2/genética , Neoplasia Endócrina Múltipla/patologia , Mixoma/patologia , Transtornos da Pigmentação/patologia , Anormalidades Múltiplas/patologia , Deleção Cromossômica , Cromossomos Artificiais Bacterianos/genética , Mapeamento de Sequências Contíguas , Feminino , Humanos , Hibridização in Situ Fluorescente , Masculino , Repetições de Microssatélites , Hibridização de Ácido Nucleico/métodos , Transtornos da Pigmentação/genética , Síndrome , Células Tumorais CultivadasAssuntos
Proteínas Quinases Dependentes de AMP Cíclico/genética , Mutação/genética , Neoplasias Hipofisárias/genética , Cromatografia Líquida de Alta Pressão , Cromossomos Humanos Par 17/genética , Análise Mutacional de DNA , Humanos , Repetições de Microssatélites/genética , Desnaturação de Ácido NucleicoRESUMO
Familial glucocorticoid deficiency due to corticotropin (ACTH) resistance consists of two distinct genetic syndromes that are both inherited as autosomal recessive traits: isolated ACTH resistance (iACTHR), which may be caused by inactivating mutations of the ACTH receptor (the MC2R gene) or mutations in an as yet unknown gene(s), and Allgrove syndrome (AS). The latter is also known as triple-A syndrome (MIM 231550). In three large cohorts of AS kindreds, the disease has been mapped to chromosome 12; most recently, mutations in the AAAS gene on 12q13 were found in these AS families. AAAS codes for the WD-repeat containing ALADIN (for alacrima-achalasia-adrenal insufficiency-neurologic disorder) protein. We investigated families with iACTHR (n = 4) and AS (n = 6) and a Bedouin family with ACTHR and a known defect of the TSH receptor. Four AS families were of mixed extraction from Puerto Rico (PR); most of the remaining six families were Caucasian families from North America (NA). Sequencing analysis found no MC2R genetic defects in any of the kindreds. No iACTHR kindreds, but all of AS families, had AAAS mutations. The previously reported IVS14+1G-->A splice donor mutation was found in all PR families, apparently due to a founder effect; one NA kindred was heterozygous for this mutation. In the latter family, long-range PCR failed to identify a deletion or other rearrangements of the AAAS gene. No other heterozygote or transmitting parent had any phenotype that could be considered part of AS. The IVS14+1G-->A mutation results in a premature termination of the predicted protein; although it was present in all PR families (in the homozygote state in three of them), there was substantial clinical variation between them. One PR family also carried a novel splice donor mutation of the AAAS gene in exon 11, IVS11+1G-->A; the proband was a compound heterozygote. A novel point mutation, 43C-->A(Gln15Lys), in exon 1 of the AAAS gene was identified in the homozygote state in a Canadian AS kindred with a milder AS phenotype. The predicted amino acid substitution in this family is located in a sequence that may participate in the preservation of stability of ALADIN beta-strands, whereas the splicing mutation in exon 11 may interfere with the formation of WD repeats in this molecule. We conclude that 1) AAAS does not appear to be frequently mutated in families with iACTHR; 2) AAAS is mutated in AS families from PR (that had previously been mapped to 12q13) and NA; and, 3) there is significant clinical variability between patients with the same AAAS defect.
Assuntos
Hormônio Adrenocorticotrópico/sangue , Hormônio Adrenocorticotrópico/fisiologia , Glucocorticoides/deficiência , Mutação/genética , Proteínas/genética , DNA/genética , DNA/isolamento & purificação , Éxons/genética , Genótipo , Humanos , Íntrons/genética , Proteínas do Tecido Nervoso , Complexo de Proteínas Formadoras de Poros Nucleares , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Síndrome , Tireotropina/fisiologiaRESUMO
Carney complex is a multiple neoplasia syndrome featuring cardiac, endocrine, cutaneous, and neural tumors, as well as a variety of pigmented lesions of the skin and mucosae. Carney complex is inherited as an autosomal dominant trait and may simultaneously involve multiple endocrine glands, as in the classic multiple endocrine neoplasia syndromes 1 and 2. Carney complex also has some similarities to McCuneAlbright syndrome, a sporadic condition that is also characterized by multiple endocrine and nonendocrine tumors. Carney complex shares skin abnormalities and some nonendocrine tumors with the lentiginoses and certain of the hamartomatoses, particularly Peutz-Jeghers syndrome, with which it shares mucosal lentiginosis and an unusual gonadal tumor, large-cell calcifying Sertoli cell tumor. Careful clinical analysis has enabled positional cloning efforts to identify two chromosomal loci harboring potential candidate genes for Carney complex. Most recently, at the 17q22-24 locus, the tumor suppressor gene PRKAR1A, coding for the type 1alpha regulatory subunit of PKA, was found to be mutated in approximately half of the known Carney complex kindreds. PRKAR1A acts a classic tumor suppressor gene as demonstrated by loss of heterozygosity at the 17q22-24 locus in tumors associated with the complex. The second locus, at chromosome 2p16, to which most (but not all) of the remaining kindreds map, is also involved in the molecular pathogenesis of Carney complex tumors, as demonstrated by multiple genetic changes at this locus, including loss of heterozygosity and copy number gain. Despite the known genetic heterogeneity in the disease, clinical analysis has not detected any corresponding phenotypic differences between patients with PRKAR1A mutations and those without. This article summarizes the clinical manifestations of Carney complex from a worldwide collection of affected patients and also presents revised diagnostic criteria for Carney complex. In light of the recent identification of mutations in the PRKAR1A gene, an estimate of penetrance and recommendations for genetic screening are provided.
Assuntos
Neoplasias do Córtex Suprarrenal/diagnóstico , Neoplasias do Córtex Suprarrenal/genética , Neoplasia Endócrina Múltipla/diagnóstico , Neoplasia Endócrina Múltipla/genética , Neoplasias do Córtex Suprarrenal/epidemiologia , Humanos , Neoplasia Endócrina Múltipla/epidemiologia , SíndromeRESUMO
Carney complex (CNC) is an autosomal dominant multiple neoplasia syndrome, which has been linked to loci on 2p16 and 17q22-24. We recently reported that PRKAR1A, which codes for the type 1A regulatory subunit of protein kinase A (PKA), is a tumor suppressor gene on chromosome 17 that is mutated in some CNC families. To evaluate the spectrum of PRKAR1A mutations, we identified its genomic structure and screened for mutations in 54 CNC kindreds (34 families and 20 patients with sporadic disease). Fourteen families were informative for linkage analysis: four of four families that mapped to 17q had PRKAR1A mutations, whereas there were no mutations found in seven families exhibiting at least one recombination with 17q. In six of the latter, CNC mapped to 2p16. PRKAR1A mutations were also found in 12 of 20 non-informative families and 7 of 20 sporadic cases. Altogether, 15 distinct PRKAR1A mutations were identified in 22 of 54 kindreds (40.7%). In 14 mutations, the sequence change was predicted to lead to a premature stop codon; one altered the initiator ATG codon. Mutant mRNAs containing a premature stop codon were unstable, as a result of nonsense-mediated mRNA decay. Accordingly, the predicted truncated PRKAR1A protein products were absent in these cells. We conclude that (i) genetic heterogeneity exists in CNC; and (ii) all of the CNC alleles on 17q are functionally null mutations of PRKAR1A. CNC is the first human disease recognized to be caused by mutations of the PKA holoenzyme, a critical component of cellular signaling.
Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/genética , Mixoma/genética , Sequência de Aminoácidos , Sequência de Bases , Linhagem Celular Transformada , Cromossomos Humanos Par 17 , Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Éxons , Genes Supressores de Tumor , Heterogeneidade Genética , Genótipo , Humanos , Dados de Sequência Molecular , Mutação , Mixoma/metabolismo , Linhagem , Fenótipo , RNA Mensageiro/metabolismoRESUMO
Carney complex (CNC) is a familial multiple neoplasia and lentiginosis syndrome (OMIM 160980, http://www.ncbi.nlm.nih.gov/omim) with features overlapping those of other multiple endocrine neoplasias and hamartomatoses, Peutz-Jeghers syndrome (PJS) in particular. Although a number of patients with CNC and ovarian tumors have been described in individual patient reports, it is unclear whether ovarian lesions constitute a component of the syndrome or are coincidental events. We investigated 18 women with CNC [age at first evaluation, 31.3+/-12.1 yr (mean +/- SD)] prospectively for the development of ovarian tumors over a period of 35.7+/-30.6 months by physical examination and pelvic ultrasonography. They were compared with 11 women (age at first evaluation, 32.9+/-17 yr) who were enrolled under the same protocol (follow up, 32.3+/-25.1 months) and served as a control group. In addition, a registry of 178 women from among a total of 309 patients with CNC was searched retrospectively for any having ovarian tumors. Seven available histological specimens were rereviewed. None of the CNC patients had ovarian tumors analogous to those of PJS. Two patients with CNC in the prospective group developed ovarian tumors and were operated upon. One had bilateral oophorectomy for asynchronous serous cystadenomas. The second patient had a unilateral serous cystadenoma. Resected tumor tissue from both patients was tested for genetic abnormalities of the chromosomal regions to which CNC genetic loci have been mapped. Both showed genomic amplification of chromosomal region 2p16. An additional 10 patients had at least 1 sonogram positive for ovarian cysts. Only 1 of the patients in the control group was found to have a persistent, simple ovarian cyst by ultrasonography. The registry of 178 CNC patients included 4 who had undergone surgery for ovarian tumors. The diagnoses included endometrioid adenocarcinoma (1 patient) and metastatic mucinous adenocarcinoma (the primary site was probably ovarian; 1 patient). In addition, 7 of 12 patients (58%) with CNC, who died of other causes, had ovarian lesions at autopsy. In conclusion, although the same stromal tumor, large-cell calcifying Sertoli cell tumor, affects the testes in CNC and PJS, we did not find such tumors in a small population of CNC patients that was studied prospectively or a larger group of CNC patients that was studied retrospectively. The results of our study also suggested that women with CNC commonly develop ovarian cysts and may be at risk for ovarian carcinoma. The chromosome 2p16 CNC locus was involved in ovarian pathology with apparent copy number gain, suggesting that at least molecularly there is some involvement of the CNC gene(s) in these lesions. Although ovarian tumors do not seem to be a major manifestation of CNC, sonography of the ovaries may be part of the initial evaluation for this genetic syndrome in women with CNC; follow-up of any identified lesion is recommended because of the possible risk for malignancy.
Assuntos
Predisposição Genética para Doença , Síndromes Neoplásicas Hereditárias/genética , Neoplasias Ovarianas/genética , Ovário/patologia , Adolescente , Adulto , Idade de Início , Carcinoma Endometrioide/genética , Carcinoma Endometrioide/patologia , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Neoplasia Endócrina Múltipla , Neoplasias Ovarianas/diagnóstico por imagem , Neoplasias Ovarianas/patologia , Estudos Prospectivos , Fatores de Tempo , Ultrassonografia , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/patologia , Neoplasias do Colo do Útero/cirurgiaRESUMO
Carney complex (CNC) is a familial multiple neoplasia and lentiginosis syndrome with features overlapping those of McCune-Albright syndrome (MAS) and other multiple endocrine neoplasia (MEN) syndromes, MEN type 1 (MEN 1), in particular. GH-producing pituitary tumors have been described in individual reports and in at least two large CNC patient series. It has been suggested that the evolution of acromegaly in CNC resembles that of the other endocrine manifestations of CNC in its chronic, often indolent, progressive nature. However, histologic and molecular evidence has not been presented in support of this hypothesis. In this investigation, the pituitary glands of eight patients with CNC and acromegaly [age, 22.9+/-11.6 yr (mean +/- SD)] were studied histologically. Tumor DNA was used for comparative genomic hybridization (CGH) (four tumors). All tumors stained for both GH and prolactin PRL (eight of eight), and some for other hormones, including alpha-subunit. Evidence for somatomammotroph hyperplasia was present in five of the eight patients in proximity to adenoma tissue; in the remaining three only adenoma tissue was available for study. CGH showed multiple changes involving losses of chromosomal regions 6q, 7q, 11p, and 11q, and gains of 1pter-p32, 2q35-qter, 9q33-qter, 12q24-qter, 16, 17, 19p, 20p, 20q, 22p and 22q in the most aggressive tumor, an invasive macroadenoma; no chromosomal changes were seen in the microadenomas diagnosed prospectively (3 tumors). We conclude that, in at least some patients with CNC, the pituitary gland is characterized by somatotroph hyperplasia, which precedes GH-producing tumor formation, in a pathway similar to that suggested for MAS-related pituitary tumors. Three GH-producing microadenomas showed no genetic changes by CGH, whereas a macroadenoma in a patient, whose advanced acromegaly was not cured by surgery, showed extensive CGH changes. We speculate that these changes represent secondary and tertiary genetic "hits" involved in pituitary oncogenesis. The data (1) underline the need for early investigation for acromegaly in patients with CNC; (2) provide a molecular hypothesis for its clinical progression; and (3) suggest a model for MAS- and, perhaps, MEN 1-related GH-producing tumor formation.
Assuntos
Adenoma/metabolismo , Adenoma/patologia , Hormônio do Crescimento Humano/metabolismo , Neoplasias Hipofisárias/metabolismo , Neoplasias Hipofisárias/patologia , Acromegalia/genética , Acromegalia/metabolismo , Acromegalia/cirurgia , Adenoma/genética , Adolescente , Adulto , DNA de Neoplasias/genética , Doenças do Sistema Endócrino/genética , Doenças do Sistema Endócrino/metabolismo , Doenças do Sistema Endócrino/patologia , Feminino , Humanos , Hibridização In Situ , Masculino , Mixoma/genética , Mixoma/metabolismo , Mixoma/patologia , Neurilemoma/genética , Neurilemoma/metabolismo , Neurilemoma/patologia , Transtornos da Pigmentação/genética , Transtornos da Pigmentação/metabolismo , Transtornos da Pigmentação/patologia , Hormônios Hipofisários/sangue , Neoplasias Hipofisárias/genética , SíndromeRESUMO
Carney complex (CNC) is a multiple neoplasia syndrome characterized by spotty skin pigmentation, cardiac and other myxomas, endocrine tumours and psammomatous melanotic schwannomas. CNC is inherited as an autosomal dominant trait and the genes responsible have been mapped to 2p16 and 17q22-24 (refs 6, 7). Because of its similarities to the McCune-Albright syndrome and other features, such as paradoxical responses to endocrine signals, genes implicated in cyclic nucleotide-dependent signalling have been considered candidates for causing CNC (ref. 10). In CNC families mapping to 17q, we detected loss of heterozygosity (LOH) in the vicinity of the gene (PRKAR1A) encoding protein kinase A regulatory subunit 1-alpha (RIalpha), including a polymorphic site within its 5' region. We subsequently identified three unrelated kindreds with an identical mutation in the coding region of PRKAR1A. Analysis of additional cases revealed the same mutation in a sporadic case of CNC, and different mutations in three other families, including one with isolated inherited cardiac myxomas. Analysis of PKA activity in CNC tumours demonstrated a decreased basal activity, but an increase in cAMP-stimulated activity compared with non-CNC tumours. We conclude that germline mutations in PRKAR1A, an apparent tumour-suppressor gene, are responsible for the CNC phenotype in a subset of patients with this disease.
Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/genética , Neoplasias das Glândulas Endócrinas/genética , Mutação , Mixoma/genética , Neoplasias/genética , Neurilemoma/genética , Pigmentação da Pele/genética , Acromegalia/genética , Alelos , Western Blotting , Cromatografia Líquida de Alta Pressão , Cromossomos Humanos Par 17 , Cromossomos Humanos Par 2 , AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Análise Mutacional de DNA , DNA Complementar/metabolismo , Éxons , Etiquetas de Sequências Expressas , Saúde da Família , Feminino , Genótipo , Mutação em Linhagem Germinativa , Homozigoto , Humanos , Íntrons , Perda de Heterozigosidade , Masculino , Repetições de Microssatélites , Dados de Sequência Molecular , Ácidos Nucleicos Heteroduplexes , Linhagem , Fenótipo , Polimorfismo GenéticoRESUMO
Ubiquitin is a highly conserved 76 amino acid protein that is generated in the cell by proteolysis of larger proteins containing either polyubiquitin chains or ubiquitin fused to carboxyl extension proteins (CEPs). In humans, the two human ubiquitin-CEP genes are Uba80 and Uba52, which code for ubiquitin fused to ribosomal protein S27a and L40, respectively. Working from a recently generated physical map of human chromosome 2p16, we determined the genetic and physical location and the genomic structure of the Uba80 gene in its entirety. A comparison of Uba80 to Uba52 revealed that the two genes share a conserved 5'-end structure, but that the structure of the ubiquitin coding regions was not conserved. Analysis of 400 bp of the promoter of Uba80 revealed strong similarity not only to the Uba52 promoter, but also to the other known human ribosomal gene promoters that have been identified to date. Homology searches also detected the presence of a pseudogene for Uba80, and the structure of this sequence feature is also reported.
Assuntos
Cromossomos Humanos Par 17 , Cromossomos Humanos Par 2 , Pseudogenes , Proteínas Ribossômicas , Ubiquitinas/genética , Sequência de Aminoácidos , Sequência de Bases , Mapeamento Cromossômico , Genes , Humanos , Dados de Sequência Molecular , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase Tipo II , Regiões Promotoras Genéticas , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido NucleicoRESUMO
OBJECT: The authors present their neurosurgical experience with Carney complex. Carney complex, characterized by spotty skin pigmentation, cardiac myxomas, primary pigmented nodular adrenocortical disease, pituitary tumors, and nerve sheath tumors (NSTs), is a recently described, rare, autosomal-dominant familial syndrome that is relatively unknown to neurosurgeons. Neurosurgery is required to treat pituitary adenomas and a rare NST, the psammomatous melanotic schwannoma (PMS), in patients with Carney complex. Cushing's syndrome, a common component of the complex, is caused by primary pigmented nodular adrenocortical disease and is not secondary to an adrenocorticotropic hormone-secreting pituitary adenoma. METHODS: The authors reviewed 14 cases of Carney complex, five from the literature and nine from their own experience. Of the 14 pituitary adenomas recognized in association with Carney complex, 12 developed growth hormone (GH) hypersecretion (producing gigantism in two patients and acromegaly in 10), and results of immunohistochemical studies in one of the other two were positive for GH. The association of PMSs with Carney complex was established in 1990. Of the reported tumors, 28% were associated with spinal nerve sheaths. The spinal tumors occurred in adults (mean age 32 years, range 18-49 years) who presented with pain and radiculopathy. These NSTs may be malignant (10%) and, as with the cardiac myxomas, are associated with significant rates of morbidity and mortality. CONCLUSIONS: Because of the surgical comorbidity associated with cardiac myxoma and/or Cushing's syndrome, recognition of Carney complex has important implications for perisurgical patient management and family screening. Study of the genetics of Carney complex and of the biological abnormalities associated with the tumors may provide insight into the general pathobiological abnormalities associated with the tumors may provide insight into the general pathobiological features of pituitary adenomas and NSTs.
Assuntos
Adenoma/cirurgia , Síndromes Neoplásicas Hereditárias/cirurgia , Neurilemoma/cirurgia , Neoplasias do Sistema Nervoso Periférico/cirurgia , Neoplasias Hipofisárias/cirurgia , Raízes Nervosas Espinhais/cirurgia , Acromegalia/diagnóstico , Acromegalia/genética , Acromegalia/cirurgia , Adenoma/diagnóstico , Adenoma/genética , Adolescente , Adulto , Aberrações Cromossômicas/genética , Transtornos Cromossômicos , Síndrome de Cushing/diagnóstico , Síndrome de Cushing/genética , Síndrome de Cushing/cirurgia , Feminino , Genes Dominantes/genética , Humanos , Masculino , Pessoa de Meia-Idade , Síndromes Neoplásicas Hereditárias/diagnóstico , Síndromes Neoplásicas Hereditárias/genética , Neurilemoma/diagnóstico , Neurilemoma/genética , Neoplasias do Sistema Nervoso Periférico/diagnóstico , Neoplasias do Sistema Nervoso Periférico/genética , Neoplasias Hipofisárias/diagnóstico , Neoplasias Hipofisárias/genética , Raízes Nervosas Espinhais/patologia , SíndromeRESUMO
The region of chromosome 2 encompassed by the polymorphic markers D2S378 (centromeric) and D2S391 (telomeric) spans an approximately 10-cM distance in cytogenetic bands 2p15-p21. This area is frequently involved in cytogenetic alterations in human cancers. It also harbors the genes for several genetic disorders, including Type I hereditary nonpolyposis colorectal cancer (HNPCC), familial male precocious puberty (FMPP), Carney complex (CNC), Doyne's honeycomb retinal dystrophy (DHRD), and one form of familial dyslexia (DYX-3). Only a handful of known genes have been mapped to 2p16. These include MSH2, which is responsible for HNPCC, FSHR, the gene responsible for FMPP, EFEMP-1, the gene mutated in DHRD, GTBP, a DNA repair gene, and SPTBN1, nonerythryocytic beta-spectrin. The genes for CNC and DYX-3 remain unknown, due to lack of a contig of this region and its underrepresentation in the existing maps. This report presents a yeast- and bacterial-artificial chromosome (YAC and BAC, respectively) resource for the construction of a sequence-ready map of 2p15-p21 between the markers D2S378 and D2S391 at the centromeric and telomeric ends, respectively. The recently published Genemap'98 lists 146 expressed sequence tags (ESTs) in this region; we have used our YAC-BAC map to place each of these ESTs within a framework of 40 known and 3 newly cloned polymorphic markers and 37 new sequence-tagged sites. This map provides an integration of genetic, radiation hybrid, and physical mapping information for the region corresponding to cytogenetic bands 2p15-p21 and is expected to facilitate the identification of disease genes from the area.
Assuntos
Mapeamento Cromossômico , Cromossomos Humanos Par 2/genética , Doenças Genéticas Inatas/genética , Mapeamento Cromossômico/métodos , Passeio de Cromossomo , Cromossomos Artificiais de Levedura , Cromossomos Bacterianos , Neoplasias Colorretais Hereditárias sem Polipose/genética , DNA Recombinante/genética , Dislexia/genética , Etiquetas de Sequências Expressas , Marcadores Genéticos , Doenças dos Genitais Masculinos/genética , Humanos , Hibridização in Situ Fluorescente , Masculino , Síndromes Neoplásicas Hereditárias/genética , Doenças Retinianas/genéticaRESUMO
BACKGROUND: Primary pigmented nodular adrenocortical disease causes the Cushing syndrome in children and young adults and is most frequently associated with the Carney complex. OBJECTIVE: To evaluate diagnostic tests for primary pigmented nodular adrenocortical disease. DESIGN: Retrospective cohort study. SETTING: Tertiary care center. PATIENTS: 21 patients with primary pigmented nodular adrenocortical disease. The control groups consisted of 9 patients with macronodular adrenocortical disease and 15 patients with primary unilateral adrenocortical disease (single adenomas). MEASUREMENTS: Clinical characteristics, radiologic imaging, and a 6-day Liddle test with determination of urinary free cortisol and 17-hydroxycorticosteroid excretion. RESULTS: Adrenal imaging and other tests were of limited value for the diagnosis of primary pigmented nodular adrenocortical disease. The Liddle test, however, distinguished patients with this disorder from those with other primary adrenocortical lesions. An increase of 50% or more in urinary free cortisol levels on day 6 of the Liddle test identified 9 of 13 patients (69.2% [95% CI, 46.6% to 91.8%]) with primary pigmented nodular adrenocortical disease, excluded all patients with macronodular adrenocortical disease, and was present in only 3 of the 15 patients with single adrenocortical adenomas (20% [CI, 0% to 40.2%]). An increase in urinary free cortisol excretion of 100% or more on day 6 of the Liddle test identified only patients with primary pigmented nodular adrenocortical disease. CONCLUSIONS: Patients with primary pigmented nodular adrenocortical disease responded to dexamethasone with a paradoxical increase in glucocorticoid excretion during the Liddle test. This feature distinguishes such patients from those who have the Cushing syndrome caused by other primary adrenal disorders and may lead to timely detection of the Carney complex (a potentially fatal disorder) in asymptomatic patients.
Assuntos
Doenças do Córtex Suprarrenal/diagnóstico , Dexametasona , Glucocorticoides , Testes de Função Adreno-Hipofisária , 17-Hidroxicorticosteroides/urina , Hormônio Adrenocorticotrópico/sangue , Adulto , Estudos de Coortes , Feminino , Humanos , Hidrocortisona/urina , Masculino , Curva ROC , Estudos Retrospectivos , Estatísticas não ParamétricasRESUMO
We report the identification and characterisation of a novel human orphan G-protein-coupled receptor (GPR) which maps to chromosome 2p16. We have determined the full-length coding sequence and genomic structure of a gene corresponding to the anonymous expressed sequenced tag, WI-31133. This gene encodes a novel protein that is 540 amino acids in length. Protein sequence analysis predicts the presence of seven transmembrane domains, a characteristic feature of GPRs. In situ hybridisation to human retina and Northern blot analysis of human retinal pigment epithelium (RPE) showed localisation of this transcript to the RPE and cells surrounding retinal arterioles. In contrast, the transcript was localised to the photoreceptor inner segments and the outer plexiform layer in mouse sections. Northern blot analysis demonstrated a 7 kb transcript highly expressed in the brain. No mutations were identified during a screen of patients suffering from Doyne's honeycomb retinal dystrophy (DHRD), an inherited retinal degeneration which maps to chromosome 2p16.