Made available in DSpace on 2016-06-02T19:22:10Z (GMT). No. of bitstreams: 1 5684.pdf: 2471155 bytes, checksum: f035dbceafb88325d3cb0d3fb8280603 (MD5) Previous issue date: 2013-12-10 / Financiadora de Estudos e Projetos / Matrix metalloproteinases (MMPs) are key factors in tumor progression that allow tumor cells to modify the extracellular matrix (ECM) and to release cytokines, growth factors being activated by cell surface molecules such as the integrins. Integrins are major adhesion receptors of cell surface that connect the cells to the external environment enabling its movement. Integrins activate signaling cascades that influence the adhesion, survival and cell proliferation. Important inhibitors of these molecules were found in snake venoms called disintegrins. Alternagin-C (ALT-C) a disintegrin from Rhinocerophis alternatus snake venom has affinity with α2β1 integrin therfore modulating cell adhesion, migration and proliferation. However, the effect of ALT-C on MMP activity has not been described yet. Here, we have found that, ALT-C increased cell migration in MDA-MB-231 at lower concentration (10 nM) and it decreased cell migration at higher concentrations (40, 100 and 1000 nM). ALT-C was able to inhibit MMP-9 activity in human breast cancer (MDA-MB-231) conditioned medium and MMP-2 activity in fibroblastas and human microvascular endothelial cells (HMEC-1) conditioned medium. ALT-C also modulated the expression of angiogenic genes such as VEGF, c-MYC, MMP-2 and MMP-9 and it was able to inhibit transendothelial migration of MDA-MB-231 cells at all concentrations (10, 40, 100 and 1000 nM). In conclusion, ALT-C affects the extracellular matrix remodeling by modulating the activity of MMPs and expression of angiogenic genes essential for tumor growth as well as decreased cell migration. / As metaloproteinases de matriz (MMPs) são fatores chave na progressão tumoral, pois participam do remodelamento da matriz extracelular (ECM), liberam citocinas, fatores de crescimento e são reguladas por moléculas da superfície celular (integrinas). As integrinas são os principais receptores de adesão da superfície celular. Elas interagem com proteínas presentes na matriz extracelular conectando as células ao meio no qual estão inseridas possibilitando sua locomoção e a participação em cascatas de sinalização que influenciam a adesão, sobrevivência e a proliferação celular. Importantes inibidores dessas moléculas foram encontrados em venenos de serpentes denominados de desintegrinas. Alternagina-C (ALT-C), uma desintegrina de veneno da serpente Rhinocerophis alternatus, tem afinidade para a integrina α2β1, modula a adesão, migração e a proliferação celular mas não há nenhum estudo publicado sobre sua influência na atividade das MMPs. Nesse estudo, a ALT-C foi capaz de aumentar a migração celular em MDA-MB-231 em baixa concentração (10 nM) e diminuir a migração em concentrações mais elevadas (40, 100 e 1000 nM). ALT-C também inibiu a atividade de MMP-9 em meio condicionado de células de carcinoma de mama (MDAMB- 231) e atividade de MMP-2 em meio condicionado de fibroblastos e células endoteliais microvasculares humanas (HMEC-1). A desintegrina também foi capaz de modular a expressão de genes angiogênicos como VEGF, c-MYC, MMP-2 e MMP-9 e inibir a transmigração das células tumorais através das células endoteliais. Conclui-se que a ALT-C atua no remodelamento da matriz extracelular do microambiente tumoral por modular a atividade de MMPs e a expressão de genes angiogênicos essenciais no crescimento tumoral, bem como diminuindo a migração celular.

<p>The PRLs are a subfamily of dual specificity phosphatases that appear to play important roles in oncogenesis. Much of the current understanding of PRL function has been either correlative, and deduced from observed PRL overexpression in pathological conditions, or from in vitro analysis of signaling pathways following PRL deletion or overexpression. Such studies, necessitated by the general lack of synthetic inhibitors or compounds to probe the substrate specificity and biological interactions of the PRLs, are nonetheless now providing critical insight into potential biological substrates and roles of the PRL phosphatases. The recent identification of PTEN as a substrate for PRL2 provided the foundation for studies to further define the role of PRL2 in oncogenesis and, by analogy, the normal physiological function of PRL2. In the studies described herein, a novel PRL2 conditional knock-out animal was generated and used to validate the PRL2/PTEN interaction in a leukemic phenotype, and further demonstrated that PRL2 inhibition can restore dysregulated PTEN/AKT pathways to significantly attenuate disease progression. Inhibition of PRL2 therefore represents a novel potential therapeutic strategy in the management and treatment of AML. This thesis project also sought to further examine the role of the PRLs in oncogenesis through their regulation and interaction of targets within the TME. Functional analyses revealed that PRL3 was the only PRL to have a prominent role in host response to TME development, and that previously proposed roles for PRL3 in angiogenesis and immune cell recruitment is dependent upon PRL3 expression and activity in cells external to the TME. The study also revealed a previously unrecognized synergism between VEGF and PRL3 in the host in promoting TME angiogenesis. The studies of PRL3 in the TME suggest the potential physiological role of PRL3 in wound healing.</p>

<p>  </p> <p>The phosphatases of regenerating liver are a subfamily of protein tyrosine phosphatases that consist of PRL1, PRL2 and PRL3. The overexpression of PRLs promote cell proliferation, migration and invasion and contribute to tumorigenesis and metastasis to aggravate survival outcome. Although there is increasing interest in understanding the implication of these phosphatases in tumor development, currently, limited knowledge is available about their mechanism of action and the efficacy of PRL inhibition in <em>in vivo</em> tumor models, the tumor extrinsic role of PRLs that allow them to impact tumor development, as well as <em>in vivo</em> physiological function of PRLs that could implicate them in diseases other than cancer. The work presented here aims to address these limitations.</p> <p><br></p>