Metastasis suppressors regulate multiple steps during the process of dissemination of tumor cells from primary sites to distant organs, while they do not affect the growth of the primary tumor. Previously, we identified NDRG1 (N-myc downstream regulated gene 1) as a tumor metastasis suppressor gene and found that it is negatively involved in metastatic progression of prostate and breast cancers. To elucidate the molecular mechanism of NDRG1 function, we used the yeast two-hybrid system to identify proteins interacting with NDRG1. In the first part of this project, we demonstrate that NDRG1, interacts with the Wnt receptor, LRP6, followed by blocking of the Wnt signaling, and therefore, orchestrates a cellular network that impairs the metastatic progression of tumor cells in vitro and in animal model. We also found that restoring NDRG1 expression by a small molecule compound significantly suppressed the capability of otherwise highly metastatic tumor cells to thrive in circulation and distant organs in animal models. In addition, our analysis of clinical cohorts data indicate that Wnt+/NDRG-/LRP+ signature has a strong predictable value for recurrence-free survival of cancer patients. Collectively, we have identified NDRG1 as a negative master regulator of Wnt signaling during the metastatic progression, and therefore revealed a novel control mechanism of Wnt signaling in tumor progression. Previously, we identified the metastasis promoting transcription factor, ATF3, as a downstream target of NDRG1. Further analysis revealed that the KAI1 promoter contained a consensus binding motif of ATF3, suggesting a possibility that NDRG1 suppresses metastasis through inhibition of ATF3 expression followed by activation of KAI1 gene. In the second part of this project, we examine a possible link between two metastasis suppressor genes, NDRG1 and KAI1, through ATF3. We demonstrated that ectopic expression of NDRG1 was able to augment endogenous KAI1gene expression in prostate cancer cell lines, while silencing NDRG1 accompanied with significant decrease in KAI1 expression in vitro and in vivo. In addition, our results of ChIP analysis indicate that ATF3 indeed bound to the promoter of KAI1 gene. Importantly, our promoter-based analysis revealed that ATF3 modulated KAI1 transcription through cooperation with other endogenous transcription factor as co-activator (ATF3-JunB) or co-repressor (ATF3-NFêB). Moreover, loss of KAI1 expression significantly abrogated NDRG1-mediated metastatic suppression in vitro as well as in a spontaneous metastasis animal model, indicating that KA11 is a functional down-stream target of NDRG1 pathway. Our result of immunohistochemical analysis showed that loss of NDRG1 and KAI1 occurs in parallel as prostate cancer progresses. We also found that a combined expression status of these two genes serves as a strong independent prognostic marker to predict metastasis-free survival of prostate cancer patients. Taken together, our result revealed a novel regulatory network of two metastasis suppressor genes, NDRG1 and KAI1, which together concerted metastasis-suppressive activities through intrinsic transcriptional cascade.

Salmonid alphaviruses (SAV) are a group of viruses that have recently emerged as a serious threat to the salmonid aquaculture industry in Europe. Over recent years, diseases caused by SAV have severely hampered the Scottish, Irish and Norwegian Atlantic salmon industry, and are considered to be among the major economically important viral diseases affecting the industry at present. Amongst the six subtypes characterised so far, Salmonid alphavirus 1 (SAV1) causes severe pathology in the heart, pancreas and the skeletal muscle of Atlantic salmon leading to death and growth retardation in the affected fish. The biochemical characteristics of the virus and the sequential pathology of the diseases caused by SAV have been described; however the mechanisms responsible for causing the disease and the host defence mechanisms against the virus are poorly defined. This thesis therefore examined the pathogenesis of SAV infection at the cellular and molecular level in vivo in salmon and in vitro in salmonid cells, with a special emphasis on host immune defence mechanisms against the virus. SAV was first isolated from Chinook salmon embryo-214 (CHSE-214) cells in 1995 in Ireland. Several cell lines have since been used to grow the virus. In the present study, three established salmonid cell lines, Chum salmon heart -1 (CHH-1), CHSE-214 and Salmon head kidney -1 (SHK-1) were evaluated for their ability to support the isolation of SAV-1 from infected fish tissue, with CHH-1 cells giving the fastest cytopathic effect (CPE) during primary isolation. The CPE appeared as localised cell-rounding on CHH-1 and CHSE-214 cells, although in SHK-1 cells, the cells were seen to slough off the monolayer relatively later than with the other two cell lines during the infection. The host response to SAV infection was evaluated by experimentally infecting Atlantic salmon parr using a cell culture-adapted virus isolate. A quantitative reverse transcription polymerase chain reaction (qRT-PCR) was developed to examine the virus load in the fish, from which it was found that the highest viral RNA copy number was detected at 5 day post infection (d.p.i), of the 90 day experimental infection period. Characteristic pathological lesions were only seen in the pancreas and the heart but not in the skeletal muscles of the infected fish. A gene expression study using qRT-PCR revealed the rapid induction of interferon (INF) and INF-associated genes in the head kidney of the infected fish compared to the control fish. The Mx protein was found to be highly expressed in the heart and the mucous membranes of infected fish by immunohistochemistry. Interestingly, the pathological changes that were seen occurred some time after the peak expression of genes associated with the INF-1-pathway. When the host-virus interaction of Atlantic salmon infected with SAV was examined using a microarray, a potent first line defence response was observed, together with the signatures of early activation of the adaptive immune response during the initial stages of the infection. Genes associated with transcription, translation and lipid metabolism were significantly differentially expressed in virus infected fish compared to control fish. A large array of antiviral genes was significantly expressed, amongst which were some of the genes also described in mammalian alphavirus infections. Genes associated with apoptosis and anti-apoptosis were also seen to be differentially regulated showing the complexity of the host-virus interaction. Collectively, all of these findings suggest that a non-specific antiviral immune response takes place providing rapid immune protection during the early stages of SAV infection in salmon. In the study on morphogenesis of SAV in salmonid cells using electron microscopy (EM), a rapid internalization of virus into the cells and generation of replication complexes using the secretory pathway of the cell, similar to mammalian alphavirus replication was observed. The mature viruses were released through surface projections, acquiring envelopes from the host cell membrane. From the ultrastructural studies of the salmonid cells infected with SAV, a progressive chromatin marginalisation and condensation could be seen, leading to cellular fragmentation, forming membrane bound apoptotic bodies, characteristic of progressive apoptosis. The activation of caspase-3 in the cytoplasm and genomic DNA damage were also seen in the infected fish cells, indicating that apoptosis is the main cause of cell death during SAV infection. The results of this study have increased our knowledge and understanding of the cellular and molecular mechanisms involved in the pathogenesis of SAV infection, emphasising the importance of the first line defence mechanisms against SAV infection in salmon. This has given an interesting insight into the host mechanisms used to combat the virus during infection, and will undoubtedly be useful for designing new vaccines and management strategies for prevention and control of this important disease

As displasias corticais focais constituem um grupo de malformações do desenvolvimento cortical cerebral. São consideradas a causa mais comum de epilepsia refratária na população pediátrica. A hemimegalencefalia faz parte deste grupo de malformação do desenvolvimento cortical e clinicamente devastadora em crianças, caracterizada pelo crescimento distorcido e anormal de um hemisfério cerebral. O mTOR (Mammalian Target of Rapamycin) é uma proteína quinase, que normalmente funciona como um regulador central de importantes funções fisiológicas, incluindo o crescimento e proliferação celular, metabolismo, autofagia, e sobrevivência e morte celular. O objetivo deste estudo foi identificar o defeito genético específico da hemimegalencefalia analisando os genes das vias de sinalização do mTOR. Foram selecionados 10 pacientes diagnosticados com hemimegalencefalia com faixa etária entre 0 á 18 anos de idade. Os pacientes submetidos ao procedimento cirúrgico foram designados para a coleta do material biológico (sangue e tecido encefálico) para análise genômica. Foram encontradas variantes somáticas de três genes relacionados a via mTOR com alto índice de patogenicidade, sendo elas; mutações missense na MTOR, HME 6584 (c.7255G> A, p.Glu2419Lys), HME 4146 (c.7498A> T, p.L7105f) mutações missense do gene PIK3CA, HME 4149 E542K (c.1624G> A), HME 4143 (c.1258T> C, p.C420R). A hipótese mediante esses resultados é que a mutação somática de genes que estão presentes na via mTOR podem ser uma das causas genéticas da HME. Essas observações sugeriram que a HME representa um espectro de distúrbios do neurodesenvolvimento resultando de distintas progenitoras que são determinados pelo tempo em que a mutação ocorreu durante o desenvolvimento cerebral. Pode-se esperar que uma mutação que ocorre precocemente durante o desenvolvimento afete um grande número de células e resulte em uma malformação maior, ao passo que a mesma mutação ocorrendo mais tarde no desenvolvimento poderia causar uma menor malformação. No futuro, numerosas mutações somáticas em genes conhecidos ou novos serão, sem dúvida, reveladas em amostras de cérebros ressecados e assim, possíveis correlações entre genótipos e fenótipos podem emergir, permitindo que o diagnóstico clínico genético ajude a prever o desfecho do paciente / Focal cortical dysplasias constitute a group of malformations of cerebral cortical development. They are considered the most common cause of refractory epilepsy in the pediatric population. Hemimegalencephaly is part of this group of malformation of cortical development and clinically devastating in children, characterized by the distorted and abnormal growth of a cerebral hemisphere. MTOR (Mammalian Target of Rapamycin) is a protein kinase, which normally functions as a central regulator of important physiological functions, including cell growth and proliferation, metabolism, autophagy, and cell death and survival. The aim of this study was to identify the specific genetic defect of hemimegalencephaly by analyzing the genes of the mTOR signaling pathways. Ten patients diagnosed with hemimegalencephaly with ages ranging from 0 to 18 years of age were selected. Patients submitted to the surgical procedure were assigned to the collection of biological material (blood and brain tissue) for genomic analysis. Somatic variants of three genes related to the mTOR pathway with high pathogenicity index were found; missense mutations in the MTOR, HME 6584 (c.7255G> A, p.Glu2419Lys), HME 4146 (c.7498A> T, p.Leu7105Phe) missense mutations of the PIK3CA gene, HME 4149 (c.1624G> A Glu542Lys), HME 4143 (c.1258 -> C, p.Cys420Arg). The hypothesis by these results is that the somatic mutation of genes that are present in the mTOR pathway may be one of the genetic causes of HME. These observations have suggested that HME represent a spectrum of neurodevelopmental disorders resulting from distinct progenitors that are determined by the time the mutation occurred during brain development. A mutation that occurs early in development may be expected to affect a large number of cells and result in a larger malformation, whereas the same mutation occurring later in development could cause a minor malformation. In the future, numerous somatic mutations in known or new genes will undoubtedly be revealed in samples of resected brains and thus, possible correlations between genotypes and phenotypes may emerge, allowing genetic clinical diagnosis to help predict the outcome of the patient

<p>A previous model of morphological pathogenesis assumed that cervical carcinoma is of monoclonal origin and progresses through multiple steps from normal epithelium via CINS into invasive carcinomas. The aim of this study was to investigate the molecular mechanism of pathogenesis of cervical neoplasia. </p><p>In the clonality study, we found that 75% (6/8) of informative cases of cervical carcinoma had identical patterns of loss of heterozygosity (LOH) in the multiple synchronous lesions, while the remaining cases had different LOU patterns. In an extensively studied "golden case", the multiple carcinoma and cervical intraepithelial neoplasia (CIN) lesions could be divided into several different clonal groups by the X-chromosome inactivation patterns, HPV 16 mutations and LOH patterns. The biggest clonal family included one CIN II, one CIN III and four carcinoma samples, while four other monoclonal families of carcinoma did not include CIN lesions. These results suggested that cervical carcinoma can be either monoclonal or polygonal and contains clones developing either directly or via multiple steps. In the study of HPV types and HPV16 variations, the results confirmed that specific HPV types are the cause of cervical carcinoma but failed to support the previous opinion that HPV16 E6 variants are more malignant than the prototype. We established a novel classification called oncogene lineage of HPV16, and found that additional variations of HPV 16 oncogenes might be a weak further risk factor for cervical carcinoma. In the study of LOH, we found that interstitial deletion of two common regions of chromosome 3p, i.e., 3p2l.1-3p2l.3, and 3p22, was an early event in the development of cervical carcinoma. The results showed that the hMLH1 gene, located in 3p22 and showing LOH in 43% of the studied cases, was not involved in the development of cervical carcinoma because neither the expression level of protein nor the gene sequence was altered in these cases. </p><p>In summary, a suggested model of molecular pathogenesis of cervical carcinoma is as follows. Specific types of HPV infect one or more committed stem cells in the basal layer of the epithelium. Fully efficient LOH events turn one (monoclonal origin) or more (polyclonal origin) HPV-infected stem cells into carcinoma cells without CIN steps. Less efficient LOH events would lead to CIN steps where some other unknown factors require to be added to facilitate the formation of carcinoma. In the absence of LOH events no carcinoma develops from the HPV-infected stem cells.</p>

A previous model of morphological pathogenesis assumed that cervical carcinoma is of monoclonal origin and progresses through multiple steps from normal epithelium via CINS into invasive carcinomas. The aim of this study was to investigate the molecular mechanism of pathogenesis of cervical neoplasia. In the clonality study, we found that 75% (6/8) of informative cases of cervical carcinoma had identical patterns of loss of heterozygosity (LOH) in the multiple synchronous lesions, while the remaining cases had different LOU patterns. In an extensively studied "golden case", the multiple carcinoma and cervical intraepithelial neoplasia (CIN) lesions could be divided into several different clonal groups by the X-chromosome inactivation patterns, HPV 16 mutations and LOH patterns. The biggest clonal family included one CIN II, one CIN III and four carcinoma samples, while four other monoclonal families of carcinoma did not include CIN lesions. These results suggested that cervical carcinoma can be either monoclonal or polygonal and contains clones developing either directly or via multiple steps. In the study of HPV types and HPV16 variations, the results confirmed that specific HPV types are the cause of cervical carcinoma but failed to support the previous opinion that HPV16 E6 variants are more malignant than the prototype. We established a novel classification called oncogene lineage of HPV16, and found that additional variations of HPV 16 oncogenes might be a weak further risk factor for cervical carcinoma. In the study of LOH, we found that interstitial deletion of two common regions of chromosome 3p, i.e., 3p2l.1-3p2l.3, and 3p22, was an early event in the development of cervical carcinoma. The results showed that the hMLH1 gene, located in 3p22 and showing LOH in 43% of the studied cases, was not involved in the development of cervical carcinoma because neither the expression level of protein nor the gene sequence was altered in these cases. In summary, a suggested model of molecular pathogenesis of cervical carcinoma is as follows. Specific types of HPV infect one or more committed stem cells in the basal layer of the epithelium. Fully efficient LOH events turn one (monoclonal origin) or more (polyclonal origin) HPV-infected stem cells into carcinoma cells without CIN steps. Less efficient LOH events would lead to CIN steps where some other unknown factors require to be added to facilitate the formation of carcinoma. In the absence of LOH events no carcinoma develops from the HPV-infected stem cells.

No description available.