Introdução: DAX1 (NR0B1), SF1 (NR5A1) e a via Wnt controlam o desenvolvimento de células progenitoras/tronco adrenais. NANOG, OCT4, SOX2 e STAT3 estão envolvidos na manutenção de células-tronco e têm papel em vários cânceres de diferentes tecidos. Ainda não está claro se esses fatores de transcrição interagem para promover a tumorigênese adrenocortical. Objetivo: Nos tumores adrenocorticais (TAC): avaliar o ganho de material genômico e a expressão de RNAm e proteica de DAX1 e SF1; avaliar a expressão de RNAm e proteica de marcadores de células-tronco (NANOG, OCT4, SOX2 e STAT3). No desenvolvimento do córtex adrenal: avaliar a expressão proteica desses genes. In vitro: avaliar a interação entre a via Wnt/Beta-catenina e a expressão de NANOG. Pacientes e Métodos: Painel de 30 córtices adrenais fetais humanos (20-38 semanas de gestação) e 14 pós-natais. Pacientes com TAC: 96 crianças/adolescentes (81% do sexo feminino, idade mediana de 1,6 anos [0,4 a 15,6 anos]) e 18 adultos (10 adenomas e 8 carcinomas, 89% do sexo feminino e idade mediana de 42,5 anos [21-66 anos]). Tecidos adrenais normais (controles para qPCR e MLPA): 13 crianças (idade mediana de 3 anos) e 13 adultos (mediana de idade de 48 anos). A expressão proteica de SF1, DAX1, STAT3, NANOG e OCT4 foi avaliada por imunohistoquímica nos TAC e nos córtices adrenais fetais e pós-natais. A expressão de RNAm de NR0B1, NR5A1, STAT3, NANOG e POU5F1 (OCT4) foi avaliada por qPCR nos TAC. Ganho ou perda de material genômico de NR0B1 e NR5A1 foi avaliada por MLPA nos TAC. In vitro, a expressão de NANOG (qPCR) foi avaliada em células adrenais H295 antes e após inibição da via Wnt/Beta-catenina com a substância PNU-74654. Resultados: Em adrenais fetais com 20 e 25 semanas de gestação detectou-se marcação intensa de SF1, DAX1, SOX2 e OCT4 na região subcapsular e marcação leve a moderada e difusa de STAT3 e NANOG. Após as 31 semanas e no período pós-natal, a marcação intensa de SF1 persistiu, porém a marcação de DAX1, STAT3, NANOG e OCT4 diminuiu ou desapareceu. Nos TAC, a marcação nuclear de SF1 foi positiva em 67% das amostras pediátricas e em 19% das amostras de adultos. Ganho de material genômico do NR5A1 foi observado em 71% dos TAC pediátricos e 33% de TAC adultos. Porém observou-se hipoexpressão do RNAm do NR5A1 em 84% dos TAC pediátricos. Nenhum ganho de material genômico ou aumento da expressão do RNAm do NR0B1 foi observado nos TAC pediátricos. Porém em 45% desses tumores detectou-se marcação nuclear. Nos TAC de pacientes adultos, houve aumento da expressão de RNAm de NR0B1 em 89% das amostras. Não se observou marcação de STAT3 nos TAC pediátricos e adultos. Porém nos pacientes adultos, a expressão do RNAm de STAT3 foi significativamente maior nos adenomas do que nos carcinomas. Por sua vez, a marcação nuclear do OCT4 associou-se significativamente com a ocorrência de metástases nos pacientes pediátricos. Nos TAC com a mutação p.S45P no gene da Beta-catenina detectou-se expressão significativamente aumentada do RNAm do NANOG. Além disso, após a inibição in vitro da via Wnt/Beta-catenina nas células tumorais adrenais houve redução significativa na expressão do RNAm de NANOG. Conclusão: Existe um padrão temporal na expressão de SF1, DAX1, STAT3, NANOG e OCT4 durante o desenvolvimento do córtex adrenal fetal, porém apenas a expressão de SF1 permanece no final da gestação e após o nascimento. TAC pediátricos exibem ganho de material gênico, aumento da expressão proteica e aparentemente redução paradoxal do RNAm do SF1 (NR5A1). Marcação nuclear de OCT4 se associa a fenótipo tumoral mais agressivo nos pacientes pediátricos. Parece exisitir interação entre a via Wnt/Beta-catenina e células-tronco, por meio do fator de transcrição NANOG, na tumorigênese adrenocortical. / Background: DAX1 (NR0B1), SF1 (NR5A1) and the Wnt pathway control adrenal stem/progenitor cells development. NANOG, OCT4, SOX2 and STAT3 are involved in the maintenance of stem cells and have role in various types of cancers in different tissues. It is still unclear whether these transcription factors interact to promote adrenocortical tumorigenesis. Objective: In adrenocortical tumors (ACT): to evaluate the gain of genomic material and the expression of mRNA and protein of DAX1 and SF1; to evaluate the mRNA and protein expression of stem cell markers (NANOG, OCT4, SOX2 and STAT3). In the development of the adrenal cortex: to evaluate the protein expression of these genes. In vitro: to evaluate the interaction between the Wnt/Beta-catenin pathway and NANOG expression. Patients & Methods: Panel of 30 fetal human adrenal cortices (20-38 gestational weeks) and 14 postnatal human adrenal cortices. ACT Patients: 96 children/ teenagers (81% female; median age of 1.6 years; 0.4-15.6 years) and 18 adults (10 adenomas and 8 carcinomas; 89% female; median age of 42.5 years; 21-66 years). Normal adrenal tissues (qPCR and MLPA controls): 13 children (median age of 3 years) and 13 adults (median age of 48 years). Protein expression of SF1, DAX1, STAT3, NANOG and OCT4 was assessed by immunohistochemistry in ACT, fetal and postnatal adrenal cortices. The mRNA expression of NR0B1, NR5A1, STAT3, NANOG and POU5F1 (OCT4) was assessed by qPCR in ACT. Gain or loss of NR0B1 and NR5A1 genomic material was assessed by MLPA in ACT. In vitro, NANOG expression (qPCR) was evaluated in H295 adrenal cells before and after inhibition of the Wnt/Beta-catenin pathway with PNU-74654. Results: In the adrenal glands at 20 and 25 gestational weeks, intense staining of SF1, DAX1, SOX2 and OCT4 was detected in the subcapsular region and a diffuse pattern mild to moderate staining of STAT3 and NANOG. After 31 weeks and in the postnatal period, intense SF1 staining persisted, but the staining of DAX1, STAT3, NANOG and OCT4 decreased or disappeared. In the ACT, the nuclear staining of SF1 was positive in 67% of pediatric samples and in 19% of adult samples. Gain of NR5A1 genomic material was observed in 71% of pediatric ACT and 33% of adult ACT. However, hypoexpression of NR5A1 mRNA was observed in 84% of pediatric ACT. No gain of genomic material or increase in mRNA expression of NR0B1 was observed in pediatric ACT. However, in 45% of these tumors nuclear staining was detected. In adult ACT, there was an increase in NR0B1 mRNA expression in 89% of the samples. No STAT3 staining was found in pediatric and adult ACT. However, in adult ACT, the STAT3 mRNA expression was significantly higher in adenomas than in carcinomas. In turn, the nuclear marking of OCT4 was significantly associated with the occurrence of metastases in pediatric patients. In the TACs with the p.S45P mutation in the Beta-catenin gene significantly increased NANOG mRNA expression was detected. In addition, after in vitro inhibition of the Wnt / Beta-catenin pathway in adrenal tumor cells there was a significant reduction in NANOG mRNA expression. Conclusion: There is a temporal pattern in the expression of SF1, DAX1, STAT3, NANOG and OCT4 during the development of the fetal adrenal cortex, but only SF1 expression remains at the end of gestation and after birth. Pediatric ACT show gain in NR5A1 gene material, increase in its protein expression but an apparent paradoxical reduction of mRNA. Nuclear staining of OCT4 is associated with more aggressive tumor phenotype in pediatric patients. There appears to be an interaction between the Wnt/Beta-catenin pathway and stem cells via NANOG, in adrenocortical tumorigenesis.

Introdução: DAX1 (NR0B1), SF1 (NR5A1) e a via Wnt controlam o desenvolvimento de células progenitoras/tronco adrenais. NANOG, OCT4, SOX2 e STAT3 estão envolvidos na manutenção de células-tronco e têm papel em vários cânceres de diferentes tecidos. Ainda não está claro se esses fatores de transcrição interagem para promover a tumorigênese adrenocortical. Objetivo: Nos tumores adrenocorticais (TAC): avaliar o ganho de material genômico e a expressão de RNAm e proteica de DAX1 e SF1; avaliar a expressão de RNAm e proteica de marcadores de células-tronco (NANOG, OCT4, SOX2 e STAT3). No desenvolvimento do córtex adrenal: avaliar a expressão proteica desses genes. In vitro: avaliar a interação entre a via Wnt/Beta-catenina e a expressão de NANOG. Pacientes e Métodos: Painel de 30 córtices adrenais fetais humanos (20-38 semanas de gestação) e 14 pós-natais. Pacientes com TAC: 96 crianças/adolescentes (81% do sexo feminino, idade mediana de 1,6 anos [0,4 a 15,6 anos]) e 18 adultos (10 adenomas e 8 carcinomas, 89% do sexo feminino e idade mediana de 42,5 anos [21-66 anos]). Tecidos adrenais normais (controles para qPCR e MLPA): 13 crianças (idade mediana de 3 anos) e 13 adultos (mediana de idade de 48 anos). A expressão proteica de SF1, DAX1, STAT3, NANOG e OCT4 foi avaliada por imunohistoquímica nos TAC e nos córtices adrenais fetais e pós-natais. A expressão de RNAm de NR0B1, NR5A1, STAT3, NANOG e POU5F1 (OCT4) foi avaliada por qPCR nos TAC. Ganho ou perda de material genômico de NR0B1 e NR5A1 foi avaliada por MLPA nos TAC. In vitro, a expressão de NANOG (qPCR) foi avaliada em células adrenais H295 antes e após inibição da via Wnt/Beta-catenina com a substância PNU-74654. Resultados: Em adrenais fetais com 20 e 25 semanas de gestação detectou-se marcação intensa de SF1, DAX1, SOX2 e OCT4 na região subcapsular e marcação leve a moderada e difusa de STAT3 e NANOG. Após as 31 semanas e no período pós-natal, a marcação intensa de SF1 persistiu, porém a marcação de DAX1, STAT3, NANOG e OCT4 diminuiu ou desapareceu. Nos TAC, a marcação nuclear de SF1 foi positiva em 67% das amostras pediátricas e em 19% das amostras de adultos. Ganho de material genômico do NR5A1 foi observado em 71% dos TAC pediátricos e 33% de TAC adultos. Porém observou-se hipoexpressão do RNAm do NR5A1 em 84% dos TAC pediátricos. Nenhum ganho de material genômico ou aumento da expressão do RNAm do NR0B1 foi observado nos TAC pediátricos. Porém em 45% desses tumores detectou-se marcação nuclear. Nos TAC de pacientes adultos, houve aumento da expressão de RNAm de NR0B1 em 89% das amostras. Não se observou marcação de STAT3 nos TAC pediátricos e adultos. Porém nos pacientes adultos, a expressão do RNAm de STAT3 foi significativamente maior nos adenomas do que nos carcinomas. Por sua vez, a marcação nuclear do OCT4 associou-se significativamente com a ocorrência de metástases nos pacientes pediátricos. Nos TAC com a mutação p.S45P no gene da Beta-catenina detectou-se expressão significativamente aumentada do RNAm do NANOG. Além disso, após a inibição in vitro da via Wnt/Beta-catenina nas células tumorais adrenais houve redução significativa na expressão do RNAm de NANOG. Conclusão: Existe um padrão temporal na expressão de SF1, DAX1, STAT3, NANOG e OCT4 durante o desenvolvimento do córtex adrenal fetal, porém apenas a expressão de SF1 permanece no final da gestação e após o nascimento. TAC pediátricos exibem ganho de material gênico, aumento da expressão proteica e aparentemente redução paradoxal do RNAm do SF1 (NR5A1). Marcação nuclear de OCT4 se associa a fenótipo tumoral mais agressivo nos pacientes pediátricos. Parece exisitir interação entre a via Wnt/Beta-catenina e células-tronco, por meio do fator de transcrição NANOG, na tumorigênese adrenocortical. / Background: DAX1 (NR0B1), SF1 (NR5A1) and the Wnt pathway control adrenal stem/progenitor cells development. NANOG, OCT4, SOX2 and STAT3 are involved in the maintenance of stem cells and have role in various types of cancers in different tissues. It is still unclear whether these transcription factors interact to promote adrenocortical tumorigenesis. Objective: In adrenocortical tumors (ACT): to evaluate the gain of genomic material and the expression of mRNA and protein of DAX1 and SF1; to evaluate the mRNA and protein expression of stem cell markers (NANOG, OCT4, SOX2 and STAT3). In the development of the adrenal cortex: to evaluate the protein expression of these genes. In vitro: to evaluate the interaction between the Wnt/Beta-catenin pathway and NANOG expression. Patients & Methods: Panel of 30 fetal human adrenal cortices (20-38 gestational weeks) and 14 postnatal human adrenal cortices. ACT Patients: 96 children/ teenagers (81% female; median age of 1.6 years; 0.4-15.6 years) and 18 adults (10 adenomas and 8 carcinomas; 89% female; median age of 42.5 years; 21-66 years). Normal adrenal tissues (qPCR and MLPA controls): 13 children (median age of 3 years) and 13 adults (median age of 48 years). Protein expression of SF1, DAX1, STAT3, NANOG and OCT4 was assessed by immunohistochemistry in ACT, fetal and postnatal adrenal cortices. The mRNA expression of NR0B1, NR5A1, STAT3, NANOG and POU5F1 (OCT4) was assessed by qPCR in ACT. Gain or loss of NR0B1 and NR5A1 genomic material was assessed by MLPA in ACT. In vitro, NANOG expression (qPCR) was evaluated in H295 adrenal cells before and after inhibition of the Wnt/Beta-catenin pathway with PNU-74654. Results: In the adrenal glands at 20 and 25 gestational weeks, intense staining of SF1, DAX1, SOX2 and OCT4 was detected in the subcapsular region and a diffuse pattern mild to moderate staining of STAT3 and NANOG. After 31 weeks and in the postnatal period, intense SF1 staining persisted, but the staining of DAX1, STAT3, NANOG and OCT4 decreased or disappeared. In the ACT, the nuclear staining of SF1 was positive in 67% of pediatric samples and in 19% of adult samples. Gain of NR5A1 genomic material was observed in 71% of pediatric ACT and 33% of adult ACT. However, hypoexpression of NR5A1 mRNA was observed in 84% of pediatric ACT. No gain of genomic material or increase in mRNA expression of NR0B1 was observed in pediatric ACT. However, in 45% of these tumors nuclear staining was detected. In adult ACT, there was an increase in NR0B1 mRNA expression in 89% of the samples. No STAT3 staining was found in pediatric and adult ACT. However, in adult ACT, the STAT3 mRNA expression was significantly higher in adenomas than in carcinomas. In turn, the nuclear marking of OCT4 was significantly associated with the occurrence of metastases in pediatric patients. In the TACs with the p.S45P mutation in the Beta-catenin gene significantly increased NANOG mRNA expression was detected. In addition, after in vitro inhibition of the Wnt / Beta-catenin pathway in adrenal tumor cells there was a significant reduction in NANOG mRNA expression. Conclusion: There is a temporal pattern in the expression of SF1, DAX1, STAT3, NANOG and OCT4 during the development of the fetal adrenal cortex, but only SF1 expression remains at the end of gestation and after birth. Pediatric ACT show gain in NR5A1 gene material, increase in its protein expression but an apparent paradoxical reduction of mRNA. Nuclear staining of OCT4 is associated with more aggressive tumor phenotype in pediatric patients. There appears to be an interaction between the Wnt/Beta-catenin pathway and stem cells via NANOG, in adrenocortical tumorigenesis.

Der Wnt/β-catenin Signalweg reguliert zusammen mit anderen Signalkaskaden die Embryogenese sowie auch die Homöostase und die Proliferation der Stammzellen im adulten Organismus. Mutationen in Komponenten dieses Signaltransduktionsweges führen zu einer aberranten Aktivierung von β-catenin und wurden in vielen verschieden Krebsarten einschließlich Darmkrebs beobachtet. Die transkriptionelle Akivität von β-catenin wird von verschiedenen nukleären Kofaktoren beeinflusst. Hierzu zählen insbesondere die Proteine der Pygopus Familie, die in Drosophila eine essentielle Rolle im kanonischen Wnt-Signalweg spielen, in Vertebraten allerdings vielmehr Kontext abhängig agieren. Insbesondere Pygo2 ist hierbei vermutlich auch an der malignen Transformation verschiedener Zelltypen mit anschließender Ausbildung von Tumoren beteiligt. Auch wenn bereits gezeigt werden konnte, dass Pygo2 in Darmtumoren überexprimiert wird, ist bisher unbekannt, ob es tatsächlich eine Rolle bei der Entstehung von intestinalen Tumoren spielt. Anhand von genetischen Experimenten in der Maus zeigt diese Arbeit zum ersten Mal in vivo, dass Pygo2 für die normale Homöostase des Darms nicht essentiell ist, aber an der Ausbildung von Darmtumoren, welche durch eine Stabilisierung von β-catenin induziert werden, beteiligt ist. Weder im embryonalen noch im adulten Darm beeinflusste der konditionale Villin-Cre bedingte Knock-out von Pygo2 in epithelialen Zellen die normale embryonale Entwicklung oder die Homöostase im adulten Darm. Auch für die Regulation von Zielgenen des Wnt/β-catenin Signalweges unter physiologischen Bedingungen scheint Pygo2 funktionell redundant zu sein. Im Gegensatz dazu verhinderte der Verlust von Pygo2 die Entstehung von β-catenin induzierten intestinalen Tumoren und normalisierte die damit verbundene Hyperproliferation sowie die erhöhte Expression von Wnt/β-catenin Zielgenen und intestinalen Stammzellmarkern. Überraschenderweise konnte die Ausbildungen von Adenomen in ApcMin/+ Mäusen durch Deletion von Pygo2 nicht verhindert werden. Der Vergleich beider Mausmodelle ergab eine erhöhte Expression von BCL9-2 in den Adenomen der ApcMin/+ Mäuse aber nicht in den Hyperplasien, die durch aktiviertes β-catenin induziert wurden. Dies könnte darauf hinweisen, dass in Apc mutierten epithelialen Zellen BCL9-2 für die Tumorprogression verantwortlich ist. Weiterhin konnte gezeigt werden, dass sowohl der knock-down von Pygo2 als auch von BCL9-2 in human Kolonkarzinomzellen die Proliferation reduzierte. Anhand von immunohistochemischen Analysen des Phosphorylierungsstatus von ERK1/2, einem „downstream“ Effektor von K-ras, konnten außerdem pERK1/2 positive Zellen in den intestinalen Adenomen von ApcMin/+ Mäusen, nicht aber in hyperproliferierenden Zellen mit stabilisierten β-catenin nachgewiesen werden. Zusammenfassend weisen die Ergebnisse dieser Arbeit daraufhin, dass die Funktion von Pygo2 im Darm Kontext abhängig ist. Während in normalen epithelialen Zellen des Darms Pygo2 offensichtlich funktionell redundant ist, scheint es für die Ausbildung von intestinalen Tumoren, welche durch dereguliertes Wnt/β-catenin induziert werden, essentiell zu sein. Daher könnte Pygo2 ein idealer Angriffspunkt für die zielgerichtete Therapie von Darmtumoren mit β-catenin Mutation sein.

Glycogen synthase kinase-3 (GSK-3) alpha and beta are central regulators of key developmental pathways, including Wnt, Hedgehog and Notch, which control stem cell activities and cellular differentiation. Both forms of GSK-3 are also regulated by receptor tyrosine kinases via the PI3K/Akt growth-promoting pathway and are involved in feedback mechanisms that maintain signaling homeostasis. These signaling systems have critical functions in mammary gland development and aberrations in them have been implicated in breast cancer. However, the role of GSK-3 in breast oncogenesis is unclear. Here, I provide evidence that maintenance of appropriate GSK-3 activity is necessary for normal acinar morphogenesis of mammary cells in the ductal/alveolar epithelium. Inadequate GSK-3 levels result in enlarged structures that often lack hollow lumens and resemble early premalignant breast cancer lesions. A potential contribution for PI3K signaling to this phenotype was identified as a PI3K inhibitor partially reversed the observed morphological defects. Mammary epithelial cell (MEC) identity also requires modulation of signals through the Wnt/beta-catenin pathway. GSK-3-depleted mammary glands not only transdifferentiate into squamous epithelium but also develop highly proliferative adenosquamous carcinomas characterized by activated beta-catenin. Furthermore, beta-catenin appears to be required for both cell fate changes and tumorigenesis in the absence of GSK-3 function. Mammary tissues engineered to enable conditional deletion of beta-catenin in a GSK-3-null background also assumed an epidermoid cell fate with ensuing tumor formation albeit with a significantly longer latency and different histopathology. The metaplastic nature of tumors observed is similar to a rare yet aggressive form of human breast disease, metaplastic breast carcinomas (MBCs). Mammospheres (MS) generated from GSK-3 depleted MECs exhibited a less compact morphology compared to those with activated beta-catenin, which also exhibited an expansion of the CD24:CD49f double positive progenitor population and enhanced self-renewal. No MS were formed by MECs lacking GSK-3 and beta-catenin. ErbB2/Neu-mediated mammary tumor progression has been associated with Wnt/beta-catenin pathway activation. Loss of beta-catenin delayed tumor onset in a constitutively active ErbB2 mouse model but did not alter either the luminal characteristics of the ensuing tumors nor their metastatic potential. Collectively these studies indicate GSK-3 plays important roles in mammary gland function thereby suppressing mammary tumor formation.

Glycogen synthase kinase-3 (GSK-3) alpha and beta are central regulators of key developmental pathways, including Wnt, Hedgehog and Notch, which control stem cell activities and cellular differentiation. Both forms of GSK-3 are also regulated by receptor tyrosine kinases via the PI3K/Akt growth-promoting pathway and are involved in feedback mechanisms that maintain signaling homeostasis. These signaling systems have critical functions in mammary gland development and aberrations in them have been implicated in breast cancer. However, the role of GSK-3 in breast oncogenesis is unclear. Here, I provide evidence that maintenance of appropriate GSK-3 activity is necessary for normal acinar morphogenesis of mammary cells in the ductal/alveolar epithelium. Inadequate GSK-3 levels result in enlarged structures that often lack hollow lumens and resemble early premalignant breast cancer lesions. A potential contribution for PI3K signaling to this phenotype was identified as a PI3K inhibitor partially reversed the observed morphological defects. Mammary epithelial cell (MEC) identity also requires modulation of signals through the Wnt/beta-catenin pathway. GSK-3-depleted mammary glands not only transdifferentiate into squamous epithelium but also develop highly proliferative adenosquamous carcinomas characterized by activated beta-catenin. Furthermore, beta-catenin appears to be required for both cell fate changes and tumorigenesis in the absence of GSK-3 function. Mammary tissues engineered to enable conditional deletion of beta-catenin in a GSK-3-null background also assumed an epidermoid cell fate with ensuing tumor formation albeit with a significantly longer latency and different histopathology. The metaplastic nature of tumors observed is similar to a rare yet aggressive form of human breast disease, metaplastic breast carcinomas (MBCs). Mammospheres (MS) generated from GSK-3 depleted MECs exhibited a less compact morphology compared to those with activated beta-catenin, which also exhibited an expansion of the CD24:CD49f double positive progenitor population and enhanced self-renewal. No MS were formed by MECs lacking GSK-3 and beta-catenin. ErbB2/Neu-mediated mammary tumor progression has been associated with Wnt/beta-catenin pathway activation. Loss of beta-catenin delayed tumor onset in a constitutively active ErbB2 mouse model but did not alter either the luminal characteristics of the ensuing tumors nor their metastatic potential. Collectively these studies indicate GSK-3 plays important roles in mammary gland function thereby suppressing mammary tumor formation.

abstract: Small Cell Carcinoma of the Ovary Hypercalcemic Type (SCCOHT) is a rare and highly aggressive ovarian cancer that affects children and young women at a mean age of 24 years. Most SCCOHT patients are diagnosed at an advanced stage and do not respond to chemotherapy. As a result, more than 75% of patients succumb to their disease within 1-2 years. To provide insights into the biological, diagnostic, and therapeutic vulnerabilities of this deadly cancer, a comprehensive characterization of 22 SCCOHT cases and 2 SCCOHT cell lines using microarray and next-generation sequencing technologies was performed. Following histological examination, tumor DNA and RNA were extracted and used for array comparative genomic hybridization and gene expression microarray analyses. In agreement with previous reports, SCCOHT presented consistently diploid profiles with few copy number aberrations. Gene expression analysis showed SCCOHT tumors have a unique gene expression profile unlike that of most common epithelial ovarian carcinomas. Dysregulated cell cycle control, DNA repair, DNA damage-response, nucleosome assembly, neurogenesis and nervous system development were all characteristic of SCCOHT tumors. Sequencing of DNA from SCCOHT patients and cell lines revealed germline and somatic inactivating mutations in the SWI/SNF chromatin-remodeling gene SMARCA4 in 79% (19/24) of SCCOHT patients in addition to SMARCA4 protein loss in 84% (16/19) of SCCOHT tumors, but in only 0.4% (2/485) of other primary ovarian tumors. Ongoing studies are now focusing on identifying treatments for SCCOHT based on therapeutic vulnerabilities conferred by ubiquitous inactivating mutations in SMARCA4 in addition to gene and protein expression data. Our characterization of the molecular landscape of SCCOHT and the breakthrough identification of inactivating SMARCA4 mutations in almost all cases of SCCOHT offers the first significant insight into the molecular pathogenesis of this disease. The loss of SMARCA4 protein is a highly sensitive and specific marker of the disease, highlighting its potential role as a diagnostic marker, and offers the opportunity for genetic testing of family members at risk. Outstanding questions remain about the role of SMARCA4 loss in the biology, histogenesis, diagnosis, and treatment of SCCOHT. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2014

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / After the progressive telomere shortening in successive cell divisions, normal somatic cells undergo a growth arrest called cellular senescence that occurs due to incomplete DNA replication. Senescence can also be activated by various types of stressful stimuli, including aberrant oncogenic signaling, oxidative stress and DNA damage. Senescent cells have limited proliferative capacity and seems to play an important role in tumorigenesis. They are also involved in the inflammation associated with aging and cancer progression. The process of senescence vary significantly between cells, but the different paths for the aging, however, converge to p53 and pRB. The network simulation is based on the model proposed by Porath using a Boolean model to represent the state of activation of genes involved, including the p16-pRb and p53-p21 pathways. The simulation includes 23 nodes representing the genes of the regulatory network where one of them represents the activation of the senescent state as a result of network processing. Experiments with human fibroblasts indicate that inactivation of both genes, p53 and pRB is necessary to block senescence. The simulations confirms that these pathways are able to trigger senescence independently. The simulation shows that pRb is essential to maintain the senescent state even when p16 and p53 are switched off, but the simultaneous inactivation of both p53 and pRB blocks senescence. In addition, the simulation shows that inactivation of the p16-pRb pathway is not essential to preserve the senescent state, however when p53-p21 pathway is inactivated, the senescent state is preserved. / Após o progressivo encurtamento dos telômeros em sucessivas divisões celulares, as células somáticas normais se submetidas a uma parada do crescimento chamado senescência celular que ocorre devido à replicação incompleta do DNA. A senescência também pode ser ativada por diversos tipos de estímulos estressantes, incluindo sinalização oncogênica aberrante, estresse oxidativo e danos ao DNA. Células senescentes têm capacidade proliferativa limitada e parecem desempenhar um papel importante na tumorigênese. Elas também estão envolvidas na inflamação associada com o envelhecimento e progressão do câncer. As vias de senescência variam significativamente entre as células, mas os caminhos diversos para a senescência, no entanto, convergem para p53 e pRb. A simulação é baseada no modelo proposto por Porath usando um modelo booleano para representar o estado de ativação dos genes envolvidos, incluindo as vias p16-pRb e a p53-p21. A simulação inclui 23 nós representando os genes da rede regulatória onde um deles representa o estado celular senescente que pode assumir estados Verdadeiro ou Falso como resultado do processamento de rede Experiências com fibroblastos humanos indicam que a inativação de ambos os genes, p53 e pRb, é necessária para bloquear a senescência. As simulações confirmam que essas vias são capazes de acionar a senescência independentemente. A simulação mostra que pRb é essencial para a manutenção do estado senescente mesmo se p16 e p53 forem desligados, no entanto a inativação simultânea de ambos p53 e pRb bloqueia senescência. Além disso, a simulação mostra que a inativação da via p16-pRb não é essencial para preservar o estado senescente, no entanto, quando a via p53-p21 é inativada, o estado senescente é preservado.

Le gène TP63 fait partie de la famille du gène suppresseur de tumeur TP53. Il code plusieurs isoformes. L’une d’entre elles, tronquée dans la région amino-terminale et appelée ΔNp63, présente des propriétés oncogéniques. Elle est impliquée dans la progression tumorale et la chimiorésistance. Sa surexpression est fréquente dans certains types de cancers. La première partie de mes travaux a consisté à identifier les facteurs de transcription impliqués dans la régulation du promoteur de ΔNp63. J’ai montré que l’expression de cette isoforme est inhibée par p53 et activée par ΔNp63 elle-même et par la β-caténine, dans des lignées de carcinome hépatocellulaire et de carcinome épidermoïde de l’œsophage. Dans des conditions physiologiques, un des types cellulaires dans lequel ΔNp63 est exprimée est la cellule basale mammaire. Il est admis que les tumeurs mammaires dites basal-like sont issues des cellules basales. Certaines de ces tumeurs présentant une surexpression de ΔNp63, nous avons émis l’hypothèse que ΔNp63 serait impliquée dans la tumorigenèse des cellules basales. Dans la deuxième partie, j’ai montré que l’expression de ΔNp63 peut être augmentée en cultivant les cellules mammaires en présence de surnageant de fibroblastes embryonnaires humains. L’identification de facteurs solubles responsables est en cours. D’autre part, j’ai caractérisé les conséquences biologiques de cette augmentation en termes de prolifération, de motilité et de survie des cellules immatures mammaires normales et tumorales. Les plus grandes modifications observées concernent (i) l’état de différenciation, les cellules surexprimant ΔNp63 présentant un phénotype plus immature ; (ii) la balance entre migration et adhésion qui penche en faveur de cette dernière. ΔNp63 semble donc être au carrefour des mécanismes de prolifération, d’adhésion, de différenciation et de motilité, processus impliqués dans la formation et l’homéostasie des tissus, mais dont l’altération peut conduire à l’initiation et à la progression tumorale ainsi qu’à la dissémination métastatique. Mes travaux apportent des informations sur le rôle de cette protéine dans ces processus et devraient, à terme, permettre de mieux comprendre la genèse de certains cancers, en particulier les carcinomes basal-like / TP63 gene belongs to the TP53 tumor suppressor gene family. It encodes several isoforms. One of these, truncated in its amino-terminal end and called ΔNp63, displays oncogenic properties. It is involved in tumor progression and chemoresistance and is overexpressed in some tumor types. The first part of my work consisted of identifying the transcription factors involved in the regulation of the ΔNp63 promoter. I have shown that ΔNp63 expression is inhibited by p53 and activated by ΔNp63 itself and by β-catenin in hepatocellular carcinoma and esophageal squamous cell carcinoma cell lines. Under physiological conditions, one of the cell types in which ΔNp63 is expressed is the mammary basal cell. The “basal-like” mammary tumor sub-type seems to stem from basal cells. As some of these tumors exhibit overexpression of ΔNp63, we hypothesized that this isoform could be involved in the genesis of basal-like tumors. In the second part, I have shown that ΔNp63 expression can be increased in mammary cells cultivated in the presence of human embryonic fibroblast supernatant. Identifying the soluble factors responsible for this increase is in progress. In parallel, I have evaluated the biological consequences of ΔNp63 overexpression in terms of proliferation, cell motility and survival of normal and malignant immature mammary cells. The main modifications relate to (i) the differentiation status, ΔNp63-overexpressing cells exhibiting a more immature phenotype; (ii) the balance between migration and adhesion that is in favor of this latter. ΔNp63 seems to be at the crossroads of proliferation, adhesion, differentiation and motility, processes implicated in tissue formation and homeostasis, but whose alteration may lead to tumor initiation and progression and to metastatic dissemination. My work provides information on the role of this isoform in these processes and should allow better understanding of the genesis of some tumor types, in particular basal-like breast carcinomas

Les récepteurs à dépendance ont la particularité d’induire deux signalisations différentes en fonction de la disponibilité de leur ligand. En présence de leur ligand, ils initient une signalisation positive favorisant notamment la survie cellulaire tandis qu’en leur absence, ils induisent la mort de la cellule par apoptose. Ils créent donc un état de dépendance de la cellule vis-à-vis du ligand pour survivre. Cette dualité fonctionnelle leur confère un rôle central dans le maintien de l’homéostasie tissulaire chez l’adulte et particulièrement dans l’intestin et le colon. En ce sens, l’apoptose induite par les récepteurs à dépendance serait un mécanisme de sauvegarde limitant l’échappement tumoral en permettant l’élimination des cellules proliférant ou migrant dans un environnement dépourvu d’une quantité suffisante de ligand. Un avantage sélectif potentiel pour une cellule tumorale serait donc de perdre cette induction de la mort cellulaire, soit via l’altération des récepteurs soit via un gain excessif d’expression du ligand. Ainsi, les travaux présentés montrent qu’un gain d’expression du ligand netrine-1 par la cellule tumorale elle-même caractérisée une fraction des tumeurs colorectales dérivées de pathologies inflammatoires chroniques et que la perte de l’expression des récepteurs à dépendance fixant la nétrine- 1 est observée dans le reste des cancers colorectaux. En particulier, nous avons montré que l’expression du gène qui code pour le récepteur de la netrin-1 UNC5C est altérée par méthylation dans 70% des cancers colorectaux, et que ce gène comporte également des mutations ponctuelles germinales dans des formes familiales de cancer colorectal, chez lesquels aucune autre mutation n’avait été décrite. Nous avons ainsi montré que les récepteurs à dépendance agissent comme des suppresseurs de tumeur conditionnels à l’absence de nétrine-1 et que l’altération de leur signalisation apoptotique constitue un avantage sélectif qui favorise la progression des cancers colorectaux / Dependence receptors share the common property of inducing two types of signaling according to their ligand availability. In the presence of their ligand, they induce a positive signal allowing cell survival whereas in its absence, they induce cell death by apoptosis. These receptors thus create cellular states of dependence on the ligands. Dependence receptors dual functionality plays a major role both during the embryonic development and in the regulation of tissue homeostasis in adult, particularly in intestine and colon. Indeed, apoptosis induced by dependence receptors would be a safeguard mechanism that restricts tumor escape by eliminating cells that would proliferate or migrate in settings of limited ligand availability. A potential selective advantage for a tumor cell would then be to loose this apoptotic signaling, either through a loss of the receptor apoptotic function or through an autocrine gain of the ligand expression. We show here than an over-expression of the ligand netrin-1 by a tumoral cell characterize a fraction of colorectal tumor derived from chronic inflammatory pathology, while the others tumors have lost the expression of netrin-1 dependence receptors. In particular, we have shown that the expression of UNC5C gene is down-regulated due to methylation of the promoter in 70% of cases, and different variants of the gene are associated with a familial form of colorectal cancer. Dependence receptors behave as conditional tumor suppressors in absence of their ligand, and the alteration of their apoptotic signaling is a selective advantage for tumoral cells and favors cancer progression

L’établissement de l’identité cellulaire est un phénomène très complexe qui implique pléthore de signaux instructifs intrinsèques et extrinsèques. Cependant, malgré les progrès importants qui ont été faits pour l’identification des régulateurs clés, les liens mécanistiques entre facteurs de transcription, épigénome, et structure de la chromatine lors de la différenciation cellulaire, et de la transformation tumorigénique des cellules, sont peu connus. Pour résoudre ces problématiques nous avons utilisé deux modèles de transition de l’identité cellulaire : la différenciation neuronale et endodermique induites par un même morphogène, l’acide rétinoïque. Concernant la transformation tumorale des cellules nous avons utilisé un système de tumorigenèse par étape de cellules primaires humaines. Nous avons conduit des études intégratives incluant des données transcriptomiques, épigénomiques, et des données concernant l’architecture de la chromatine. Notre approche systématique pour caractériser l’acquisition de l’identité cellulaire, combinée à la modélisation de la transduction du signal, renforce donc nos connaissances sur les mécanismes responsables de la plasticité cellulaire. Une meilleure compréhension des mécanismes régulateurs de l’identité cellulaire non seulement nous éclaire sur les relations de cause à effet entre les différents niveaux de régulation dans la cellule, mais aussi ouvre de nouvelles possibilités en terme de transdifférenciation dirigée. / The cell fate acquisition is a highly complex phenomenon that involves a plethora of intrinsic and extrinsic instructive signals. However, despite the important progress in identification of key regulatory factors of this process, the mechanistic links between transcription factors, epigenome and chromatin structure which coordinate the regulation of cell differentiation and deregulation of gene networks during cell transformation are largely unknown. To address these questions for two model systems of cell fate transitions, namely the neuronal and endodermal cell differentiation induced by the morphogen retinoic acid and the stepwise tumorigenesis of primary human cells, we conducted integrative transcriptome, epigenome and chromatin architecture studies. Through extensive integration with thousands of available genomic data sets, we deciphered the gene regulatory networks of these processes and revealed new insights in the molecular circuitry of cell fate acquisition. The understanding of regulatory mechanisms that underlie the cell fate decision processes not only brings the fundamental understanding of cause-and-consequence relationships inside the cell, but also open the doors to the directed trans-differentiation.