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No description available.

Glucose transporter 3 (GLUT3), while first found in human fetal muscle, is predominantly expressed in brain and neural tissue. By several independent techniques we have previously shown that GLUT3 is expressed in human skeletal muscle cells. The structure of the human GLUT3 gene has not been previously reported nor has there been any evaluation of the 5′-untranslated region (UTR). To this end, we have cloned and sequenced the human GLUT3 gene. Insulin-like growth factor-1 (IGF-1) increased endogenous Glut3 protein in cultured L6 myotubes, and similarly stimulated luciferase activity in a construct of the human GLUT3 5′-UTR linked to a luciferase reporter gene. Actinomycin D, an inhibitor of mRNA synthesis, prevented IGF-1 stimulation of Glut3 protein. Transfection of L6 cells with Sp1 increased Glut3 and augmented IGF-1 stimulation of Glut3 expression. Knockdown of Glut3 expression in cultured L6 muscle cells using small interference RNA (siRNA) specific for Glut3 significantly reduced myocyte glucose uptake. DNAse footprinting and gel shift assays showed Sp1 specifically bound to the human GLUT3 5′-UTR. Substitution mutants of the human GLUT3 5′-UTR luciferase construct indicated that only one of three Sp1 site clusters was involved in IGF-1 action. These data, using both a human GLUT3 5′-UTR construct and L6 cells' endogenous promoter, suggest that IGF-1 plays a role in maintaining muscle GLUT3 expression and basal glucose uptake via the transcriptional factor Sp1.

Spinal Muscular Atrophy (SMA) is a debilitating neurodegenerative disease resulting in death of the lower motor neurons, muscle atrophy, and in severe cases death. Due to mutations or deletions in the Survival Motor Neuron 1 (SMN1) gene, levels of functional SMN protein product are decreased. While SMA was previously described as a motor neuron exclusive disorder, recent evidence suggests that many tissue and cell types throughout the body are affected. The objective of our study was to outline the effects of varying levels of SMN depletion on two genes of interest, namely Insulin-like growth factor 1 (Igf-1) and Tumor suppressor protein 53 (Trp53) in multiple tissues throughout disease course. The severe Smn2B/- and mild Smn2B/-; SMN2+/- mouse models of SMA were utilized in our studies to determine the levels of mRNA expression and subsequent protein output for these two genes. We employed RT-qPCR, western blot, and ELISA experimental methods. In Smn2B/- mice, Igf-1 mRNA was substantially decreased in symptomatic liver tissue. This was accompanied by widespread decrease in IGF-1 protein in peripheral tissues. Interestingly, this depletion effect on Igf-1 was not observed in the mild mouse model. Our analysis also showed that Trp53 mRNA was dramatically increased within tibialis anterior skeletal muscle of symptomatic Smn2B/- mice, alongside an upregulation of factors involved in p53 mediated apoptosis. Once again, this effect was not observed in the mild Smn2B/-; SMN2+/- mouse model. Overall, we have demonstrated that the extent of SMN depletion, determines whether the expression of Igf-1 and Trp53 is perturbed, suggesting that disease severity is an important factor in what pathways are affected. Finally, we show that alterations in gene expression patterns or subsequent protein levels act in a tissue-specific fashion. More investigation is encouraged to highlight IGF-1’s role as a potential SMN-independent therapeutic for SMA.

O Diabetes mellitus é um distúrbio metabólico de etiologia múltipla que leva a uma hiperglicemia, podendo ocasionar inúmeras disfunções e falências de alguns órgãos e também alterações em cavidade oral. Estudos demonstraram diminuição da glicemia de ratas diabéticas com o uso de laser de baixa potência (LBP) em glândulas salivares. Como o insulin-like growth factor 1 (IGF-1) tem uma estrutura semelhante a da insulina, podendo mimetizar algumas de suas funções, o objetivo do presente trabalho foi analisar o efeito da irradiação com LBP na concentração de IGF-1, nas glândulas parótidas (GP) e submandibulares (GSM), e o efeito na glicemia de ratas diabéticas induzidas por estreptozotocina. Ratas da raça Wistar foram utilizadas e receberam uma injeção intraperitoneal de estreptozotocina ou de tampão conforme o grupo ao qual pertenciam, C (controle) ou D (diabético). Posteriormente, as ratas foram divididas em 4 subgrupos (C0, D0, C5 e D5), de acordo com a dose de irradiação recebida (0 ou 5 J/cm²). O estado diabético dos animais foi confirmado através da glicemia e, após 29 dias, os animais foram submetidos à simulação ou irradiação. O LBP utilizado foi o Photon Lase III (DMC Equipamentos LTDA®). Vinte e quatro horas após o procedimento os animais foram sacrificados para coleta de sangue e das glândulas salivares para as análises da glicemia (método da glicose oxidase e do glicosímetro) e concentração de IGF-1, respectivamente. Os resultados foram analisados pelo teste estatístico de Análise de Variância (ANOVA) e teste de contraste de Tukey, admitindo-se significância de 5%. A glicemia do dia do sacrifício, dos animais diabéticos que receberam irradiação, estava diminuída quando comparada com a glicemia de sacrifício dos animais diabéticos que não receberam o laser (p0,05). Além disso, a glicemia de sacrifício dos animais diabéticos irradiados foi menor que a aferida no dia do diagnóstico, quando foi utilizado o método do glicosímetro (p0,05). A concentração de IGF-1, entretanto, não sofreu influência da doença e nem da irradiação, se mostrando alterada somente quando comparada a GP e GSM. Com base nestes resultados podemos concluir que o LBP pode alterar a glicemia dos animais diabéticos, no entanto, este efeito parece não estar relacionado com a concentração de IGF-1. / Diabetes mellitus is a metabolic disorder of multiple etiologies that leads to hyperglycemia and can cause numerous dysfunctions and failures of some organs and also changes in the oral cavity. Studies have shown a decrease on glucose blood concentration in diabetic rats when low-power laser was used upom salivary glands. As insulin-like growth factor 1 (IGF-1) has a structure similar to insulin, the aim of this study was to analyze the effect of low-power laser irradiation on IGF-1 concentration of the parotid and submandibular glands as well as on glycemia of diabetic rats induced by streptozotocin. Wistar rats were used and received an intraperitoneal injection of streptozotocin or buffer, depending on the group to which they belonged, being C (control) or D (diabetic). Subsequently, the rats were divided into 4 subgroups (C0, D0, C5 and D5) according to the irradiation dose received (0 or 5 J / cm ²). The diabetic state of the animals was confirmed by blood glucose concentration and, after 29 days, the animals were subjected to irradiation or simulation, depending on the group to which they belonged. The laser used was the Photon Lase III (DMC Equipamentos LTDA®). Twenty-four hours after the procedure, the animals were sacrificed and blood and the salivary glands were collected to analyse the glycemia and IGF-1 concentration, respectively. The results were analyzed by Analysis of Variance statistical test (ANOVA) and Tukey\'s contrast test, assuming a significance of 5%. The sacrifice day glycemia of diabetic animals that received irradiation was decreased in comparison with the sacrifice day glycemia of non-irradiated diabetic animals as well as was lower than that measured on the day of diagnosis of irradiated animals (p0,05). The concentration of IGF-1, however, was not affected by diabetes or irradiation. However, IGF-1 concentration was increased on parotid than submandibular glands. Based on these results of the present study, we conclude that LBP can decrease blood glucose concentration of diabetic animals, however, this effect does not appear to be related to the concentration of IGF-1.

Malnutrition, when it is chronic disease in childhood, causes a reduction in growth and endocrine adaptive changes to ensure the maintenance of life. In this regard, the IGF-1 and cortisol have been identified as markers of nutritional status of children with growth deficiency. These high levels of cortisol and low levels of IGF-1 favor gliconoegenese and release of fatty acids by adipose tissue and inhibit the action of GH-dependent somatomedin-C on the growth. For these reasons, it is also important to investigate levels of total cholesterol, and triglycerides. Associated with energy deficiency, observed in these malnourished children, there is a lack of vitamins and minerals. Anemia due to iron deficiency is currently the most common nutritional deficiency in the world, followed by vitamin A deficiency. The iron and vitamin A are essential for normal growth and development. In addition to inadequate food intake, intestinal parasites have been considered important factors in the etiology of the anemia and the malnutrition. In this context, this study found a population with a poor and homogeneous socio-economic status, where the number of children was associated with the degree of malnutrition presented by the children studied (p = 0.03). Most of the children had between 12 and 36 months, was poly-infected (79.7%) and anemic (44.3%), the latter also highly associated with the degree of malnutrition (p = 0.01). For the levels of cortisol, the majority of children were in normal limits. Moreover, most of the levels of IGF-1 was next to the lower limit, showing its fall during the chronic malnutrition and its association with the same (p = 0.02). The results of lipid profile revealed that the vast majority of children had at least one type of dyslipidemia (98.9%) and low levels of HDL was associated with the degree of malnutrition (p = 0.02). It is, therefore, that chronic malnutrition presented by the children studied generates endocrine adaptations that cause permanent changes in lipid profile. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A desnutrição, quando ocorre de forma crônica na infância, causa redução no crescimento e alterações endócrinas adaptativas para garantir a manutenção da vida. Neste sentido, o IGF-1 e o cortisol têm sido indicados como marcadores do estado nutricional dessas crianças com déficit de estatura. Os altos níveis de cortisol e os baixos níveis de IGF-1 favorecem a gliconoegênese e a liberação de ácidos graxos pelo tecido adiposo e inibem a ação do GH dependentes de IGF-1 no crescimento. Por estes motivos, é importante investigar também o perfil lipídico. Associada a deficiência energética, verificada nessas crianças desnutridas, observa-se a carência de vitaminas e minerais. A anemia por carência de ferro é, atualmente, a deficiência nutricional mais freqüente no mundo, seguida pela hipovitaminose A. O ferro e a vitamina A são essenciais para o crescimento e desenvolvimento normais. Além da inadequada ingestão de alimentos, as parasitoses intestinais têm sido consideradas importantes fatores na etiologia das anemias carênciais e da DEP. Dentro deste contexto, o presente estudo objetivou estudar o perfil sócio-econômico, nutricional e bioquímico de crianças atendidas no Centro de Recuperação e Educação Nutricional (CREN/AL). Para tal foram selecionadas 79 crianças com idades entre 12 e 71 meses. Os dados sócio-econômicos e a avaliação antropométrica foram realizados em consulta nutricional. As dosagens bioquímicas foram realizadas entre os meses de junho e julho de 2008. Nesta época, foi coletada uma amostra de 10 ml de sangue em jejum de 12 horas, para dosagens de IGF-1, vitamina A sérica, hemograma e lipidograma completos. A dosagem do cortisol salivar foi realizada em um segundo momento para que o estresse da retirada do sangue não interferisse no resultado do mesmo. A presente pesquisa encontrou uma população com uma condição sócio-econômica precária e homogênea, onde o número de filhos encontrou-se associado ao grau de desnutrição apresentado pelas crianças estudadas (p= 0,03). A maior parte das crianças tinha entre 12 e 36 meses, encontrava-se poliparasitada (79,7%) e apresentaram anemia (44,3%), esta última altamente associada também ao grau de desnutrição (p= 0,01). As dosagens de vitamina A demonstraram um resultado surpreendente, pois não foi encontrado nenhum caso de hipovitaminose A, revelando que a suplementação de vitamina A implementada pelo Governo Federal tem sido eficiente. Com relação aos níveis de cortisol, a maioria das crianças encontrava-se dentro da normalidade. Por outro lado, a maior parte dos níveis de IGF-1 permearam o limite inferior, revelando sua queda durante a desnutrição crônica e sua forte associação com a mesma (p= 0,02). Os resultados do lipidograma revelaram que quase a totalidade das crianças apresentou pelo menos um tipo de dislipidemia (98,9%), sendo os níveis baixos de HDL associados ao grau de desnutrição (p= 0,02). Conclui-se, portanto, que a desnutrição crônica apresentada pelas crianças estudadas gera adaptações endócrinas que provocam modificações permanentes no perfil lipídico.

O Diabetes mellitus é um distúrbio metabólico de etiologia múltipla que leva a uma hiperglicemia, podendo ocasionar inúmeras disfunções e falências de alguns órgãos e também alterações em cavidade oral. Estudos demonstraram diminuição da glicemia de ratas diabéticas com o uso de laser de baixa potência (LBP) em glândulas salivares. Como o insulin-like growth factor 1 (IGF-1) tem uma estrutura semelhante a da insulina, podendo mimetizar algumas de suas funções, o objetivo do presente trabalho foi analisar o efeito da irradiação com LBP na concentração de IGF-1, nas glândulas parótidas (GP) e submandibulares (GSM), e o efeito na glicemia de ratas diabéticas induzidas por estreptozotocina. Ratas da raça Wistar foram utilizadas e receberam uma injeção intraperitoneal de estreptozotocina ou de tampão conforme o grupo ao qual pertenciam, C (controle) ou D (diabético). Posteriormente, as ratas foram divididas em 4 subgrupos (C0, D0, C5 e D5), de acordo com a dose de irradiação recebida (0 ou 5 J/cm²). O estado diabético dos animais foi confirmado através da glicemia e, após 29 dias, os animais foram submetidos à simulação ou irradiação. O LBP utilizado foi o Photon Lase III (DMC Equipamentos LTDA®). Vinte e quatro horas após o procedimento os animais foram sacrificados para coleta de sangue e das glândulas salivares para as análises da glicemia (método da glicose oxidase e do glicosímetro) e concentração de IGF-1, respectivamente. Os resultados foram analisados pelo teste estatístico de Análise de Variância (ANOVA) e teste de contraste de Tukey, admitindo-se significância de 5%. A glicemia do dia do sacrifício, dos animais diabéticos que receberam irradiação, estava diminuída quando comparada com a glicemia de sacrifício dos animais diabéticos que não receberam o laser (p0,05). Além disso, a glicemia de sacrifício dos animais diabéticos irradiados foi menor que a aferida no dia do diagnóstico, quando foi utilizado o método do glicosímetro (p0,05). A concentração de IGF-1, entretanto, não sofreu influência da doença e nem da irradiação, se mostrando alterada somente quando comparada a GP e GSM. Com base nestes resultados podemos concluir que o LBP pode alterar a glicemia dos animais diabéticos, no entanto, este efeito parece não estar relacionado com a concentração de IGF-1. / Diabetes mellitus is a metabolic disorder of multiple etiologies that leads to hyperglycemia and can cause numerous dysfunctions and failures of some organs and also changes in the oral cavity. Studies have shown a decrease on glucose blood concentration in diabetic rats when low-power laser was used upom salivary glands. As insulin-like growth factor 1 (IGF-1) has a structure similar to insulin, the aim of this study was to analyze the effect of low-power laser irradiation on IGF-1 concentration of the parotid and submandibular glands as well as on glycemia of diabetic rats induced by streptozotocin. Wistar rats were used and received an intraperitoneal injection of streptozotocin or buffer, depending on the group to which they belonged, being C (control) or D (diabetic). Subsequently, the rats were divided into 4 subgroups (C0, D0, C5 and D5) according to the irradiation dose received (0 or 5 J / cm ²). The diabetic state of the animals was confirmed by blood glucose concentration and, after 29 days, the animals were subjected to irradiation or simulation, depending on the group to which they belonged. The laser used was the Photon Lase III (DMC Equipamentos LTDA®). Twenty-four hours after the procedure, the animals were sacrificed and blood and the salivary glands were collected to analyse the glycemia and IGF-1 concentration, respectively. The results were analyzed by Analysis of Variance statistical test (ANOVA) and Tukey\'s contrast test, assuming a significance of 5%. The sacrifice day glycemia of diabetic animals that received irradiation was decreased in comparison with the sacrifice day glycemia of non-irradiated diabetic animals as well as was lower than that measured on the day of diagnosis of irradiated animals (p0,05). The concentration of IGF-1, however, was not affected by diabetes or irradiation. However, IGF-1 concentration was increased on parotid than submandibular glands. Based on these results of the present study, we conclude that LBP can decrease blood glucose concentration of diabetic animals, however, this effect does not appear to be related to the concentration of IGF-1.

As Distrofias Musculares Progressivas constituem um grupo de doenças genéticas caracterizadas por uma degeneração progressiva e irreversível da musculatura esquelética. As diferentes abordagens terapêuticas propostas para esse grupo de doenças têm como enfoque restaurar a proteína muscular deficiente por meio da terapia celular ou terapia gênica, ou o tratamento dos sinais e sintomas patológicos do músculo pela administração de fármacos e/ou fatores de crescimento. A combinação de diferentes estratégias pode aumentar a eficiência do reparo muscular. Deste modo, este trabalho tem como objetivo principal avaliar o potencial terapêutico das célulastronco mesenquimais (MSCs) associadas ao fator de crescimento semelhante à insulina (IGF-1) para diferentes tipos de distrofias musculares. Inicialmente avaliamos o potencial miogênico de MSCs humanas de cordão umbilical in vitro. Nossos resultados demonstraram que os fatores solúveis liberados pelo músculo distrófico de camundongos mdx foram capazes de induzir a diferenciação miogênica terminal das células-tronco. Além disso, verificamos que o IGF-1, por si só, é capaz de promover a miogênese de MSCs, com mais eficiência que os protocolos de indução padrões. Ainda nos estudos in vitro, demonstramos que MSCs são capazes de interagir com células musculares de pacientes com Distrofia Muscular de Duchenne (DMD) e restaurar a expressão de distrofina, quando cultivadas em meios suplementados com IGF-1. Frente a estes resultados, prosseguimos com os estudos em modelos animais, in vivo, e demonstramos que as MSCs humanas de cordão umbilical e IGF-1, quando administrados conjuntamente por via sistêmica, são capazes de modular a inflamação, reduzir a fibrose, aumentar o reparo muscular e, consequentemente, promover uma melhora clínica significativa do músculo de camundongos LAMA2dy/2j - modelo murino de Distrofia Muscular Congênita. Cabe ressaltar que as células humanas não foram rejeitadas após administração sistêmica em modelos animais não imunossuprimidos. Esses resultados suportam o potencial uso combinado de MSCs de cordão umbilical humano e IGF-1 no tratamento de distrofias musculares. Contudo, a confirmação destes dados em um modelo animal de grande porte, como os modelos caninos de distrofia muscular, é de extrema importância visando o entendimento dos mecanismos envolvidos no reparo muscular e avaliação de eventuais efeitos adversos, o que pode representar um passo importante para o início dos testes clínicos em pacientes / Progressive muscular dystrophies are a clinically and genetically heterogeneous group of disorders caused by the deficiency or abnormal muscle proteins, resulting in progressive degeneration and loss of skeletal muscle function. Strategies for the development of a muscular dystrophy therapy have focused on the possibility of restoring the defective muscle protein by cell therapy or on delivery of growth factors to treat or ameliorate muscular pathology symptoms. Combining both strategies could be a very useful approach to enhance the efficiency of muscle repair. The aim of this study is to evaluate the therapeutic potential of human mesenchymal stem cells (MSCs) from umbilical cord tissue combined with IGF-1 for muscle regeneration. Firstly, we verified the myogenic potential of these cells in vitro. Our results demonstrated that the soluble factors released from mdx dystrophic muscle were able to promote the myogenic differentiation of MSCs. Moreover, we showed that IGF-1 is capable of enhancing considerably the myogenesis of human MSCs from UC in vitro. More interestingly, we showed that IGF-1 enhances the interaction of MSCs and DMD muscle cells in coculture and the restoration of dystrophin expression. Subsequently, our in vivo studies revealed that the association of IGF-1 and MSCs markedly reduced muscle inflammation and fibrosis, and significantly improved muscle strength in LAMA2dy/2j mice, a murine model for congenital muscular dystrophy. It is important to point out that human cells are not rejected even in xenotransplants without immunosuppression. In summary, our results suggest that a combinatorial strategy of both IGF-1 and MSCs could enhance the efficiency of muscle repair and, therefore, should be further tested as a potential therapeutic approach in muscular dystrophies. However it is important to repeat the experiments on canine dystrophic model (GRMD; Golden Retriever Muscular Dystrophy) - in order to enhance our knowledge about the mechanism involved in muscle repair and monitor any eventual long-term side effects, which could represent an important point to start the clinical trial in patients

As Distrofias Musculares Progressivas constituem um grupo de doenças genéticas caracterizadas por uma degeneração progressiva e irreversível da musculatura esquelética. As diferentes abordagens terapêuticas propostas para esse grupo de doenças têm como enfoque restaurar a proteína muscular deficiente por meio da terapia celular ou terapia gênica, ou o tratamento dos sinais e sintomas patológicos do músculo pela administração de fármacos e/ou fatores de crescimento. A combinação de diferentes estratégias pode aumentar a eficiência do reparo muscular. Deste modo, este trabalho tem como objetivo principal avaliar o potencial terapêutico das célulastronco mesenquimais (MSCs) associadas ao fator de crescimento semelhante à insulina (IGF-1) para diferentes tipos de distrofias musculares. Inicialmente avaliamos o potencial miogênico de MSCs humanas de cordão umbilical in vitro. Nossos resultados demonstraram que os fatores solúveis liberados pelo músculo distrófico de camundongos mdx foram capazes de induzir a diferenciação miogênica terminal das células-tronco. Além disso, verificamos que o IGF-1, por si só, é capaz de promover a miogênese de MSCs, com mais eficiência que os protocolos de indução padrões. Ainda nos estudos in vitro, demonstramos que MSCs são capazes de interagir com células musculares de pacientes com Distrofia Muscular de Duchenne (DMD) e restaurar a expressão de distrofina, quando cultivadas em meios suplementados com IGF-1. Frente a estes resultados, prosseguimos com os estudos em modelos animais, in vivo, e demonstramos que as MSCs humanas de cordão umbilical e IGF-1, quando administrados conjuntamente por via sistêmica, são capazes de modular a inflamação, reduzir a fibrose, aumentar o reparo muscular e, consequentemente, promover uma melhora clínica significativa do músculo de camundongos LAMA2dy/2j - modelo murino de Distrofia Muscular Congênita. Cabe ressaltar que as células humanas não foram rejeitadas após administração sistêmica em modelos animais não imunossuprimidos. Esses resultados suportam o potencial uso combinado de MSCs de cordão umbilical humano e IGF-1 no tratamento de distrofias musculares. Contudo, a confirmação destes dados em um modelo animal de grande porte, como os modelos caninos de distrofia muscular, é de extrema importância visando o entendimento dos mecanismos envolvidos no reparo muscular e avaliação de eventuais efeitos adversos, o que pode representar um passo importante para o início dos testes clínicos em pacientes / Progressive muscular dystrophies are a clinically and genetically heterogeneous group of disorders caused by the deficiency or abnormal muscle proteins, resulting in progressive degeneration and loss of skeletal muscle function. Strategies for the development of a muscular dystrophy therapy have focused on the possibility of restoring the defective muscle protein by cell therapy or on delivery of growth factors to treat or ameliorate muscular pathology symptoms. Combining both strategies could be a very useful approach to enhance the efficiency of muscle repair. The aim of this study is to evaluate the therapeutic potential of human mesenchymal stem cells (MSCs) from umbilical cord tissue combined with IGF-1 for muscle regeneration. Firstly, we verified the myogenic potential of these cells in vitro. Our results demonstrated that the soluble factors released from mdx dystrophic muscle were able to promote the myogenic differentiation of MSCs. Moreover, we showed that IGF-1 is capable of enhancing considerably the myogenesis of human MSCs from UC in vitro. More interestingly, we showed that IGF-1 enhances the interaction of MSCs and DMD muscle cells in coculture and the restoration of dystrophin expression. Subsequently, our in vivo studies revealed that the association of IGF-1 and MSCs markedly reduced muscle inflammation and fibrosis, and significantly improved muscle strength in LAMA2dy/2j mice, a murine model for congenital muscular dystrophy. It is important to point out that human cells are not rejected even in xenotransplants without immunosuppression. In summary, our results suggest that a combinatorial strategy of both IGF-1 and MSCs could enhance the efficiency of muscle repair and, therefore, should be further tested as a potential therapeutic approach in muscular dystrophies. However it is important to repeat the experiments on canine dystrophic model (GRMD; Golden Retriever Muscular Dystrophy) - in order to enhance our knowledge about the mechanism involved in muscle repair and monitor any eventual long-term side effects, which could represent an important point to start the clinical trial in patients

Bone metastases are a frequent clinical complication associated with cancer. The aim of this PhD thesis was to set up a model system for the study of tumour cell – bone cell interactions in vitro, ex vivo and in vivo and to use this system to test the efficacy of a novel therapeutic agent for the treatment of osteolytic bone disease. Co-culture or conditioned medium studies using human or mouse cancer cell lines were used to develop an in vitro model system of tumour cell – bone cell interactions. This showed that osteolytic tumour cells enhance osteoclast formation, fusion and resorption through the production of various factors that act directly on osteoclasts and their precursors. And in addition, that osteolytic tumour cells also enhance osteoclastogenesis indirectly via increasing the production of RANKL in osteoblasts. Other effects on osteoblasts included reductions in differentiation, migration and adhesion. Successful ex vivo and in vivo models for the study of tumour – induced osteolysis were created using adapted organ cultures and intratibial injection techniques respectively. IGF-1 and its receptor are known to play important roles in both bone metabolism and breast cancer. Therefore a study of the effects of IGF-1 receptor inhibition on tumour cell – bone cell interactions was performed. In vitro studies showed that the novel IGF-1 receptor tyrosine kinase inhibitor PQIP significantly inhibited IGF-1 and breast cancer enhanced osteoclast formation. Western blot analysis suggested this may be due to the inhibition of both IGF-1 and cancer conditioned medium induced PI3k/Akt activation. Moreover, treatment of osteoblasts with PQIP inhibited cancer cell conditioned medium induced increases in RANKL production. Ex vivo studies using human MDA-MB-231 – mouse calvarial organ co-cultures demonstrated that MDA-MB-231 cells caused osteolysis and this was completely prevented by PQIP without affecting cancer cell viability. Furthermore, once daily oral administration of PQIP significantly decreased trabecular bone loss and reduced the size of osteolytic bone lesions following mouse 4T1 breast cancer cell intratibial injection in mice. Quantitative histomorphometry showed a significant reduction in breast cancer-induced osteoclast number and activity. Consistent with the significant inhibition of osteoblast differentiation, spreading, migration and bone nodule formation observed in vitro, PQIP also inhibited osteoblast number and bone formation in vivo. No inhibition of in vivo tumour volume was observed. These findings clearly suggest that oral PQIP treatment reduced the rate of cancer associated bone turnover. In conclusion, this thesis successfully demonstrates a model system for investigating tumour cell-bone cell interactions in vitro, ex vivo and in vivo. Using this model system I showed that pharmacologic inhibition of IGF-1 receptor kinase activity using PQIP inhibits osteoclast and osteoblast changes induced by breast cancer cells in vitro and in vivo and prevents osteolysis ex vivo and in vivo. This indicates that PQIP and its novel derivatives which are now in advanced clinical development may be of value in the treatment of osteolytic bone disease associated with breast cancer.