Ovarian cancer accounts for more deaths than all other gynaecological cancers taken together. The 5 year survival rate can be as high as 80% for cases diagnosed early, but the asymptomatic nature of the disease means that it is most frequently detected in the later stages. By this time, disease has invariably spread beyond the ovaries and the survival rate drops to around 30%. Treatment of ovarian cancer often fails due to a high rate of chemoresistance and novel methods of treatment and detection are required to increase the survival chances of patients. This study sought to determine whether gene therapy for sporadic ovarian cancer could offer a novel and more successful treatment option for the disease. Mutation or abnormal expression of the p53 gene has already been shown to be the most common genetic even in ovarian cancer, being involved in up to 70% of cases. Wild-type p53 was delivered, using liposomes, into p53 mutant ovarian cancer cell lines and this resulted in a restoration of the wild-type functions of the gene, namely cell cycle arrest and apoptosis. The results from the cell line studies suggested that restoration of the wild-type p53 function limit or reduce tumour progression and increase the sensitivity of the tumour to chemotherapy. A mouse model of human peritoneal ovarian cancer was then constructed and the wild-type p53 gene was administered in liposomes into the peritoneum. The results suggested that p53 gene therapy prevents tumours from growing in the mice, when compared to a control gene. It is now known that p53 gene therapy for humans is being clinically assessed. There are a proportion of tumours that do not harbour an abnormal p53 gene, raising the possibility that other tumour suppressor gene mutations may play a role in the molecular genetic control of growth arrest and apoptosis. P53-dependent, apoptosis-regulating family members bcl-2 and bax were analysed immunohistochemically to determine their involvement in ovarian cancer. Both proteins were significantly associated with malignancy and also with overall length of survival, but not associated with the various prognostic factors such as stage and differentiation of tumour. It is unlikely that these genes will become targets for gene therapy in ovarian cancer. Mutation, deletion and hypermethylation of the p53-independent pi6 gene, alter its function, resulting in loss of G1 cell cycle arrest control. The status of methylation of the pi 6 promoter in ovarian tumours was determined and combined with mutation data, resulting in the conclusion that abnormal pi 6 was not a common event in ovarian cancer and is therefore not a likely candidate for gene therapy. This study has contributed to the evergrowing wealth of knowledge on the molecular genetic events of ovarian cancer, and has shown that gene therapy for sporadic ovarian cancer as a clinical application is feasible.

Ovarian cancer (OC) is the deadliest gynecologic malignancy with a substantial proportion of hereditary cases and a frequent association with breast cancer (BC). Genetic testing facilitates preventive management for carriers of mutations in OC-susceptibility genes. However, the prevalence of germline mutations varies among populations and many rarely mutated OC predisposition genes remain to be identified. We analyzed 219 genes in 1333 Czech OC patients and 2278 population-matched controls (PMC) using next-generation sequencing. Altogether, 427/1333 (32%) patients and 58 /2278 (2,5%) PMC carried pathogenic mutations in 18 known/anticipated OC predisposition genes. Mutations in BRCA1, BRCA2, RAD51C, RAD51D, BARD1 and mismatch repair genes conferred a high OC risk (with OR>5). Mutations in BRIP1 and NBN were associated with moderate risk (both OR ≥2 - <5). BRCA1/2 mutations dominated in almost all clinicopathological subgroups including sporadic borderline tumors of ovary (BTO). Analysis of remaining 201 genes revealed somatic mosaics in PPM1D and germline mutations in SHPRH and NAT1 associating with a high/moderate OC risk significantly; however, further studies are warranted to delineate their contribution to OC development in other populations. Results of this study demonstrate the high proportion...

A maioria dos casos de puberdade precoce central (PPC) em meninas permanece idiopática. A hipótese de uma causa genética vem se fortalecendo após a descoberta de alguns genes associados a este fenótipo, sobretudo aqueles implicados com o sistema kisspeptina (KISS1 e KISS1R). Entretanto, apenas casos isolados de PPC foram relacionados à mutação na kisspeptina ou em seu receptor. Até recentemente, a maioria dos estudos genéticos em PPC buscava genes candidatos selecionados com base em modelos animais, análise genética de pacientes com hipogonadismo hipogonadotrófico, ou ainda, nos estudos de associação ampla do genoma. Neste trabalho, foi utilizado o sequenciamento exômico global, uma metodologia mais moderna de sequenciamento, para identificar variantes associadas ao fenótipo de PPC. Trinta e seis indivíduos com a forma de PPC familial (19 famílias) e 213 casos aparentemente esporádicos foram inicialmente selecionados. A forma familial foi definida pela presença de mais de um membro afetado na família. DNA genômico foi extraído dos leucócitos do sangue periférico de todos os pacientes. O estudo de sequenciamento exômico global realizado pela técnica ILLUMINA, em 40 membros de 15 famílias com PPC, identificou mutações inativadoras em um único gene, MKRN3, em cinco dessas famílias. Pesquisa de mutação no MKRN3 realizada por sequenciamento direto em duas famílias adicionais (quatro pacientes) identificou duas novas variantes nesse gene. O MKRN3 é um gene de um único éxon, localizado no cromossomo 15 em uma região crítica para a síndrome de Prader Willi. O gene MKRN3 sofre imprinting materno, sendo expresso apenas pelo alelo paterno. A descoberta de mutações em pacientes com PPC familial despertou o interesse para a pesquisa de mutações nesse gene em 213 pacientes com PPC aparentemente esporádica por meio de reação em cadeia de polimerase seguida de purificação enzimática e sequenciamento automático direto (Sanger). Três novas mutações e duas já anteriormente identificadas, incluindo quatro frameshifts e uma variante missense, foram encontradas, em heterozigose, em seis meninas não relacionadas. Todas as novas variantes identificadas estavam ausentes nos bancos de dados (1000 Genomes e Exome Variant Server). O estudo de segregação familial em três dessas meninas com PPC aparentemente esporádica e mutação no MKRN3 confirmou o padrão de herança autossômica dominante com penetrância completa e transmissão exclusiva pelo alelo paterno, demonstrando que esses casos eram, na verdade, também familiares. A maioria das mutações encontradas no MKRN3 era do tipo frameshift ou nonsense, levando a stop códons prematuros e proteínas truncadas e, portanto, confirmando a associação com o fenótipo. As duas mutações missenses (p.Arg365Ser e p.Phe417Ile) identificadas estavam localizadas em regiões de dedo ou anel de zinco, importantes para a função da proteína. Além disso, os estudos in silico dessas duas variantes demonstraram patogenicidade. Todos os pacientes com mutação no MKRN3 apresentavam características clínicas e hormonais típicas de ativação prematura do eixo reprodutivo. A mediana de idade de início da puberdade foi de 6 anos nas meninas (variando de 3 a 6,5) e 8 anos nos meninos (variando de 5,9 a 8,5). Tendo em vista o fenômeno de imprinting, análise de metilação foi também realizada em um subgrupo de 52 pacientes com PPC pela técnica de MS-MLPA, mas não foram encontradas alterações no padrão de metilação. Em conclusão, este trabalho identificou um novo gene associado ao fenótipo de PPC. Atualmente, mutações inativadoras no MKRN3 representam a causa genética mais comum de PPC familial (33%). O MKRN3 é o primeiro gene imprintado associado a distúrbios puberais em humanos. O mecanismo preciso de ação desse gene na regulação da secreção de GnRH necessita de estudos adicionais / Most cases of central precocious puberty (CPP) in girls remain idiopathic. The hypothesis of a genetic cause has been strengthened after the discovery of some genes associated with this phenotype, particularly those involved with the kisspeptin system (KISS1 and KISS1R). However, genetic defects in KISS1 and its receptor are rare and have been identified in only a few patients with CPP.over the past years. To date, most genetic studies in CPP was based mainly on a candidate gene approach, including genes selected in animal studies, human models of patients with hypogonadotropic hypogonadism or in genome wide association studies. In the present study, we used whole exome sequencing, a more advanced method of sequencing, to identify variants associated with CPP. Thirty-six patients with the familial form of CPP (19 families) and 213 apparently sporadic cases were initially selected. The familial form was defined by the presence of more than one member affected in the family. Genomic DNA was extracted from peripheral blood leukocytes in all patients. Whole exome sequencing performed by ILLUMINA technique in 40 members of 15 families with CPP, identified inactivating mutations in a single gene, MKRN3, in five out of these families. Analysis of MKRN3 mutations performed by automatic sequencing in two additional families (four patients) identified two novel mutations. MKRN3 is an introless gene located on chromosome 15, in the Prader Willi syndrome critical region, and it is expressed only by the paternal allele due to the maternal imprinting. Following the initial findings, we searched for MKRN3 mutations in 213 patients with apparently sporadic CPP using polymerase chain reaction followed by direct enzymatic purification and automated sequencing (Sanger). Three new mutations and two previously reported, including four frameshifts and one missense variant was identified in six unrelated girls with CPP. All variants were not described in the two databases (1000 Genomes and Exome Variant Server). The familial segregation analysis performed in three out of these girls with apparently sporadic CPP and MKRN3 mutations confirmed the autosomal dominant inheritance with complete penetrance and exclusive transmission through the paternal allele, revealing familial inheritance in apparently sporadic cases. Most of these MKRN3 mutations were frameshifts or nonsense, leading to premature stop codons and truncated proteins, thus demonstrating positive genotype- phenotype correlation. The two missense mutations (p.Arg365Ser and p.Phe417Ile) identified were located within zinc finger motifs, regions predicted to be essential for the protein function. Besides that, all missense mutations were predicted to be pathogenic by in silico analysis. All patients carrying MKRN3 mutations exhibited typical clinical and hormonal features of premature activation of the reproductive axis. The median age of puberty onset was 6.0 years in girls (ranging from 3.0 to 6.5) and 8.0 years in boys (ranging from 5.9 to 8.5). In view of the imprinting phenomenon, methylation analysis was also performed in a subgroup of 52 patients with CPP by MSMLPA technique, but no methylation abnormalities were detected. In conclusion, our work has identified a new gene associated with CPP. Currently, inactivating mutations in MKRN3 represent the most common genetic cause of familial CPP (33%). MKRN3 is the first imprinted gene associated with pubertal disorders in humans. However, its precise mechanism of action in the regulation of GnRH secretion needs further studies

A maioria dos casos de puberdade precoce central (PPC) em meninas permanece idiopática. A hipótese de uma causa genética vem se fortalecendo após a descoberta de alguns genes associados a este fenótipo, sobretudo aqueles implicados com o sistema kisspeptina (KISS1 e KISS1R). Entretanto, apenas casos isolados de PPC foram relacionados à mutação na kisspeptina ou em seu receptor. Até recentemente, a maioria dos estudos genéticos em PPC buscava genes candidatos selecionados com base em modelos animais, análise genética de pacientes com hipogonadismo hipogonadotrófico, ou ainda, nos estudos de associação ampla do genoma. Neste trabalho, foi utilizado o sequenciamento exômico global, uma metodologia mais moderna de sequenciamento, para identificar variantes associadas ao fenótipo de PPC. Trinta e seis indivíduos com a forma de PPC familial (19 famílias) e 213 casos aparentemente esporádicos foram inicialmente selecionados. A forma familial foi definida pela presença de mais de um membro afetado na família. DNA genômico foi extraído dos leucócitos do sangue periférico de todos os pacientes. O estudo de sequenciamento exômico global realizado pela técnica ILLUMINA, em 40 membros de 15 famílias com PPC, identificou mutações inativadoras em um único gene, MKRN3, em cinco dessas famílias. Pesquisa de mutação no MKRN3 realizada por sequenciamento direto em duas famílias adicionais (quatro pacientes) identificou duas novas variantes nesse gene. O MKRN3 é um gene de um único éxon, localizado no cromossomo 15 em uma região crítica para a síndrome de Prader Willi. O gene MKRN3 sofre imprinting materno, sendo expresso apenas pelo alelo paterno. A descoberta de mutações em pacientes com PPC familial despertou o interesse para a pesquisa de mutações nesse gene em 213 pacientes com PPC aparentemente esporádica por meio de reação em cadeia de polimerase seguida de purificação enzimática e sequenciamento automático direto (Sanger). Três novas mutações e duas já anteriormente identificadas, incluindo quatro frameshifts e uma variante missense, foram encontradas, em heterozigose, em seis meninas não relacionadas. Todas as novas variantes identificadas estavam ausentes nos bancos de dados (1000 Genomes e Exome Variant Server). O estudo de segregação familial em três dessas meninas com PPC aparentemente esporádica e mutação no MKRN3 confirmou o padrão de herança autossômica dominante com penetrância completa e transmissão exclusiva pelo alelo paterno, demonstrando que esses casos eram, na verdade, também familiares. A maioria das mutações encontradas no MKRN3 era do tipo frameshift ou nonsense, levando a stop códons prematuros e proteínas truncadas e, portanto, confirmando a associação com o fenótipo. As duas mutações missenses (p.Arg365Ser e p.Phe417Ile) identificadas estavam localizadas em regiões de dedo ou anel de zinco, importantes para a função da proteína. Além disso, os estudos in silico dessas duas variantes demonstraram patogenicidade. Todos os pacientes com mutação no MKRN3 apresentavam características clínicas e hormonais típicas de ativação prematura do eixo reprodutivo. A mediana de idade de início da puberdade foi de 6 anos nas meninas (variando de 3 a 6,5) e 8 anos nos meninos (variando de 5,9 a 8,5). Tendo em vista o fenômeno de imprinting, análise de metilação foi também realizada em um subgrupo de 52 pacientes com PPC pela técnica de MS-MLPA, mas não foram encontradas alterações no padrão de metilação. Em conclusão, este trabalho identificou um novo gene associado ao fenótipo de PPC. Atualmente, mutações inativadoras no MKRN3 representam a causa genética mais comum de PPC familial (33%). O MKRN3 é o primeiro gene imprintado associado a distúrbios puberais em humanos. O mecanismo preciso de ação desse gene na regulação da secreção de GnRH necessita de estudos adicionais / Most cases of central precocious puberty (CPP) in girls remain idiopathic. The hypothesis of a genetic cause has been strengthened after the discovery of some genes associated with this phenotype, particularly those involved with the kisspeptin system (KISS1 and KISS1R). However, genetic defects in KISS1 and its receptor are rare and have been identified in only a few patients with CPP.over the past years. To date, most genetic studies in CPP was based mainly on a candidate gene approach, including genes selected in animal studies, human models of patients with hypogonadotropic hypogonadism or in genome wide association studies. In the present study, we used whole exome sequencing, a more advanced method of sequencing, to identify variants associated with CPP. Thirty-six patients with the familial form of CPP (19 families) and 213 apparently sporadic cases were initially selected. The familial form was defined by the presence of more than one member affected in the family. Genomic DNA was extracted from peripheral blood leukocytes in all patients. Whole exome sequencing performed by ILLUMINA technique in 40 members of 15 families with CPP, identified inactivating mutations in a single gene, MKRN3, in five out of these families. Analysis of MKRN3 mutations performed by automatic sequencing in two additional families (four patients) identified two novel mutations. MKRN3 is an introless gene located on chromosome 15, in the Prader Willi syndrome critical region, and it is expressed only by the paternal allele due to the maternal imprinting. Following the initial findings, we searched for MKRN3 mutations in 213 patients with apparently sporadic CPP using polymerase chain reaction followed by direct enzymatic purification and automated sequencing (Sanger). Three new mutations and two previously reported, including four frameshifts and one missense variant was identified in six unrelated girls with CPP. All variants were not described in the two databases (1000 Genomes and Exome Variant Server). The familial segregation analysis performed in three out of these girls with apparently sporadic CPP and MKRN3 mutations confirmed the autosomal dominant inheritance with complete penetrance and exclusive transmission through the paternal allele, revealing familial inheritance in apparently sporadic cases. Most of these MKRN3 mutations were frameshifts or nonsense, leading to premature stop codons and truncated proteins, thus demonstrating positive genotype- phenotype correlation. The two missense mutations (p.Arg365Ser and p.Phe417Ile) identified were located within zinc finger motifs, regions predicted to be essential for the protein function. Besides that, all missense mutations were predicted to be pathogenic by in silico analysis. All patients carrying MKRN3 mutations exhibited typical clinical and hormonal features of premature activation of the reproductive axis. The median age of puberty onset was 6.0 years in girls (ranging from 3.0 to 6.5) and 8.0 years in boys (ranging from 5.9 to 8.5). In view of the imprinting phenomenon, methylation analysis was also performed in a subgroup of 52 patients with CPP by MSMLPA technique, but no methylation abnormalities were detected. In conclusion, our work has identified a new gene associated with CPP. Currently, inactivating mutations in MKRN3 represent the most common genetic cause of familial CPP (33%). MKRN3 is the first imprinted gene associated with pubertal disorders in humans. However, its precise mechanism of action in the regulation of GnRH secretion needs further studies

A neoplasia endócrina múltipla tipo 2 (NEM-2) é uma síndrome tumoral herdada por mutações germinativas no proto-oncogene RET (RET) e transmitida por herança autossômica dominante. Atualmente, a indicação de tireoidectomia total preventiva é recomendada a indivíduos portadores de mutações no RET. Analisamos a aplicação do método Eletroforese em Gel Sensível à Conformação (CSGE) no rastreamento de mutações hot-spots do RET. Sete famílias com NEM-2 foram rastreadas pelo CSGE, seqüenciamento gênico e análise do Polimorfismo Conformacional de Cadeia Simples (SSCP). Usando o CSGE e SSCP, identificamos cinco das seis (83,3%) mutações verificadas pelo seqüenciamento: Cys620Arg, Cys634Arg, Cys634Tyr, Val648Ile e Met918Thr. Foram analisados 128 amplicons englobando mutações hot-spots do RET e 116 dentre 128 (90.6%) concordaram com o seqüenciamento genético. Os polimorfismos 691 e 769 também foram documentados pelo CSGE e SSCP. Os dados obtidos por CSGE e SSCP foram totalmente (100%) concordantes. O CSGE revelou ser metodologia sensível, rápida, fácil de ser executada e de baixo custo na detecção de mutações nos códons 620, 634, 648, e 918, as quais constituem grande maioria (~95%) dos pacientes com NEM-2. Quanto à mutação Val804Met (prevalência na população inferior a 3%), o método necessita ser otimizado. Concluímos que o CSGE é uma metodologia efetiva para o rastreamento de mutações que mais freqüentemente ocorrem no RET como causadora de NEM-2. / Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited tumor syndrome caused by activating germline mutations in RET proto-oncogene (RET). Presently, the prophylactic total thyroidectomy is recommended to all RET mutations carriers. Here we tested the Conformation Sensitive Gel Electrophoresis (CSGE) as a screening method for the RET hot-spot mutations. Seven MEN2 families were studied by CSGE, as well as by Single Strand Conformational Polymorphism (SSCP) and direct sequencing analysis. Using CSGE and SSCP, we were able to detect five out of the six (83.3%) RET mutations verified by direct sequencing analysis: Cys620Arg, Cys634Arg, Cys634Tyr, Val648Ile and Met918Thr. RET polymorphisms 691 and 769 were verified by CSGE and SSCP. In our sample, data obtained using CSGE were fully concordant (100%) with SSCP findings. Thus, CSGE showed to be a sensitive, fast, low-cost, and ease procedure to detect RET mutations in codons 620, 634, 648, and 918 which are reported as the most prevalent RET variants (~95%) in large MEN2 series. As to the Val804Met mutation (prevalence in the population lower than 3%), this method still needs to be optimized. We concluded that CSGE is an effective screening method for the most frequent RET hot-spot disease-causing mutations.

A neoplasia endócrina múltipla tipo 2 (NEM-2) é uma síndrome tumoral herdada por mutações germinativas no proto-oncogene RET (RET) e transmitida por herança autossômica dominante. Atualmente, a indicação de tireoidectomia total preventiva é recomendada a indivíduos portadores de mutações no RET. Analisamos a aplicação do método Eletroforese em Gel Sensível à Conformação (CSGE) no rastreamento de mutações hot-spots do RET. Sete famílias com NEM-2 foram rastreadas pelo CSGE, seqüenciamento gênico e análise do Polimorfismo Conformacional de Cadeia Simples (SSCP). Usando o CSGE e SSCP, identificamos cinco das seis (83,3%) mutações verificadas pelo seqüenciamento: Cys620Arg, Cys634Arg, Cys634Tyr, Val648Ile e Met918Thr. Foram analisados 128 amplicons englobando mutações hot-spots do RET e 116 dentre 128 (90.6%) concordaram com o seqüenciamento genético. Os polimorfismos 691 e 769 também foram documentados pelo CSGE e SSCP. Os dados obtidos por CSGE e SSCP foram totalmente (100%) concordantes. O CSGE revelou ser metodologia sensível, rápida, fácil de ser executada e de baixo custo na detecção de mutações nos códons 620, 634, 648, e 918, as quais constituem grande maioria (~95%) dos pacientes com NEM-2. Quanto à mutação Val804Met (prevalência na população inferior a 3%), o método necessita ser otimizado. Concluímos que o CSGE é uma metodologia efetiva para o rastreamento de mutações que mais freqüentemente ocorrem no RET como causadora de NEM-2. / Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited tumor syndrome caused by activating germline mutations in RET proto-oncogene (RET). Presently, the prophylactic total thyroidectomy is recommended to all RET mutations carriers. Here we tested the Conformation Sensitive Gel Electrophoresis (CSGE) as a screening method for the RET hot-spot mutations. Seven MEN2 families were studied by CSGE, as well as by Single Strand Conformational Polymorphism (SSCP) and direct sequencing analysis. Using CSGE and SSCP, we were able to detect five out of the six (83.3%) RET mutations verified by direct sequencing analysis: Cys620Arg, Cys634Arg, Cys634Tyr, Val648Ile and Met918Thr. RET polymorphisms 691 and 769 were verified by CSGE and SSCP. In our sample, data obtained using CSGE were fully concordant (100%) with SSCP findings. Thus, CSGE showed to be a sensitive, fast, low-cost, and ease procedure to detect RET mutations in codons 620, 634, 648, and 918 which are reported as the most prevalent RET variants (~95%) in large MEN2 series. As to the Val804Met mutation (prevalence in the population lower than 3%), this method still needs to be optimized. We concluded that CSGE is an effective screening method for the most frequent RET hot-spot disease-causing mutations.