Colorectal cancer (CRC) is the third leading cause of death from cancer in North America. The KRAS gene is mutated in approximately 40-50% of all CRC, and this mutation precludes treatment with promising targeted therapeutics. c-MET is a receptor tyrosine kinase that is overexpressed in ~70% of CRCs, and expression is correlated with disease progression. We hypothesized that high c-MET plus mutant KRAS would result poor survival of CRC patients, by activating unique signalling pathways that may be targeted for therapeutic purposes. To this end, we used phosphoproteomics in a KRAS mutant cell line, and identified proteins phosphorylated on tyrosine in response to HGF stimulation, including a subset of those that contain SRC family kinase consensus motifs. Small molecule inhibitors of either SRC or c-MET reduced tyrosine phosphorylation of both proteins, indicating reciprocal signalling. We chose the c-MET target p190RhoGAP for future study, as it is often ubiquitously bound to p120RasGAP via phosphorylated tyrosine. We found that RasGAP expression is mediated in part by KRAS signalling, and that expression of RasGAP could partly rescue tumourigenicity of a CRC cell line where the mutant KRAS allele has been inactivated, indicating the requirement of both mutant KRAS and RasGAP expression in this model. We then conclude by looking at CRC patient samples to determine the role of KRAS mutation in the progression and survival of CRC. We found that both KRAS and c-MET copy number are correlated to KRAS mutation status, and that c-MET polysomy plus KRAS mutation leads to worse overall survival than KRAS mutation alone. Overall, we identified novel targets of c-MET and KRAS oncogenic signaling, and identify a population which may derive the most benefit from treatments targeting both of these lesions.

Colorectal cancer (CRC) is the third leading cause of death from cancer in North America. The KRAS gene is mutated in approximately 40-50% of all CRC, and this mutation precludes treatment with promising targeted therapeutics. c-MET is a receptor tyrosine kinase that is overexpressed in ~70% of CRCs, and expression is correlated with disease progression. We hypothesized that high c-MET plus mutant KRAS would result poor survival of CRC patients, by activating unique signalling pathways that may be targeted for therapeutic purposes. To this end, we used phosphoproteomics in a KRAS mutant cell line, and identified proteins phosphorylated on tyrosine in response to HGF stimulation, including a subset of those that contain SRC family kinase consensus motifs. Small molecule inhibitors of either SRC or c-MET reduced tyrosine phosphorylation of both proteins, indicating reciprocal signalling. We chose the c-MET target p190RhoGAP for future study, as it is often ubiquitously bound to p120RasGAP via phosphorylated tyrosine. We found that RasGAP expression is mediated in part by KRAS signalling, and that expression of RasGAP could partly rescue tumourigenicity of a CRC cell line where the mutant KRAS allele has been inactivated, indicating the requirement of both mutant KRAS and RasGAP expression in this model. We then conclude by looking at CRC patient samples to determine the role of KRAS mutation in the progression and survival of CRC. We found that both KRAS and c-MET copy number are correlated to KRAS mutation status, and that c-MET polysomy plus KRAS mutation leads to worse overall survival than KRAS mutation alone. Overall, we identified novel targets of c-MET and KRAS oncogenic signaling, and identify a population which may derive the most benefit from treatments targeting both of these lesions.

c-Met is a tyrosine receptor kinase which is activated by its only ligand, the hepatocyte growth factor (HGF). Activation of c-Met leads to a wide spectrum of biological activities such as motility, angiogenesis, morphogenesis, cell survival and cell regeneration. c-Met and HGF knock-out mice are embryonic lethal. During embryogenesis, c-Met is required for liver, kidney and skeletal muscles development. In adult tissues, c-Met is involved in wound healing and hepatocyte regeneration. c-Met is abnormally activated in many tumours types. Aberrant c-Met activation was found to induce tumour development, tumour cell migration and invasion, and the worst and final step in cancer progression, metastasis. In addition, c-Met activation in cells was also shown to confer resistance to apoptosis induced by UV damage or chemotherapeutic drugs. c-Met is thus an attractive target for drug development. This study describes the development of monoclonal antibodies against c-Met as therapeutic molecules in cancer treatment/diagnostics. Antibodies were raised against the a-chain of c-Met. 21 hybridoma clones were single-cell cloned and subjected to preliminary monoclonal antibody characterisation. 11 monoclonal antibodies were finally selected for ascites production and antibody purification. These purified antibodies were characterised by Western blotting, immunofluorescence staining, functional assays (ERK phosphorylation and cell scatter) and for their ability to recognise native c-Met by flow cytometry. Some of the anti-a-chain c-Met antibodies perform better in Western blotting and immunofluorescence staining than the presently-available commercial antibodies. The Mab 2.1 and 13.1 bind strongly to native c-Met in flow cytometry and may be potential candidates for antibody therapy and cancer diagnostics.

Zugl.: Tübingen, Universiẗat, Diss., 2008.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Introduction: Basal-like (BL) breast cancer is an aggressive sub-type of breast cancer for which there is no targeted systemic therapy. C-Met is a receptor tyrosine kinase implicated in breast cancer. Clinical trials assessing the efficacy of anti-c-Met therapy are underway, yet few studies have analysed the clinical significance of c-Met expression and/or activation in breast cancer, in particular whether there is a correlation with molecular sub-type. The aims of this study are: 1) to establish the clinical significance of c-Met expression in invasive breast cancer, 2) evaluate the novel proximity ligation assay (PLA) as a method of measuring c-Met activation and 3) address the effect of hepatocyte growth factor (HGF)-mediated c-Met phosphorylation on migration and protein expression in cell lines representative of the BL sub-type. Methods: Immunohistochemistry for c-Met was performed on 1455 cases of breast cancer using tissue microarray (TMA) technology. The PLA was performed on TMAs constructed from 181 breast cancers. C-Met expression and the PLA product were correlated with clinico-pathological parameters and survival. The effects of HGF on cell migration and protein expression were assessed using migration assays, western blots and immunofluorescent studies. Results: C-Met expression was independently associated with BL breast cancer (odds ratio = 6.44, 95% confidence interval (CI) = 1.74-23.78, p = 0.005) and reduced overall survival (hazard ratio = 1.81, 95% CI = 1.07-3.06), p = 0.026). The PLA signal was not associated with molecular sub-type or survival. HGF stimulation was associated with a significant increase in BL cell migration (p < 0.01) but no evidence of epithelial-mesenchymal transition was observed. Conclusion: My findings suggest BL breast cancer patients should be included in future trials of anti-c-Met therapy. Further work is necessary to establish the prognostic utility of the PLA as a measure of c-Met activation and the mechanisms driving HGF-mediated cell migration.

El sarcoma de Kaposi (SK) es una enfermedad angioproliferativa con cuatro formas clínico-epidemiológicas: clásica (SK-C), africana endémica, relacionada con fármacos inmunosupresores y relacionada con el síndrome de inmunodeficiencia adquirida (SK-SIDA). La afectación del SK es generalmente cutánea, pero en los casos agresivos puede diseminarse a localizaciones extracutáneas. En la piel, las lesiones se clasifican clínicopatológicamente en máculas, placas y tumores de acuerdo con su progresión y severidad. El SK parece iniciarse como una proliferación vascular reactiva debida a una red de citocinas alterada, mientras que en estadios avanzados, se comporta como una neoplasia multifocal.El diferente comportamiento biológico del SK de acuerdo con sus presentaciones epidemiológicas y estadios puede estar relacionado con la presencia de alteraciones específicas en los mecanismos que controlan el crecimiento y desarrollo tumoral, como la sobreestimulación de citocinas y de factores de crecimiento angiogénicos o alteraciones en las oncoproteínas que controlan la proliferación celular y la apoptosis. Estas alteraciones podrían ofrecer los estímulos neoplásicos necesarios para el desarrollo, progresión y, en definitiva, un comportamiento más agresivo del SK.El factor de crecimiento hepatocitario (HGF) es una citocina angiogénica pleiotrópica que está sobreexpresada en cánceres humanos invasivos y puede actuar como factor de progresión tumoral, estimulando la angiogénesis y la invasividad de las células tumorales. Estas respuestas son transducidas a través del receptor c-Met. El HGF estimula la proliferación de las células fusiformes cultivadas de lesiones humanas de SK, y además las células del SK sintetizan y secretan HGF y expresan c-Met, creando un rizo de retroalimentación para la proliferación tumoral y la neovascularización. Hemos estudiado la expresión del c-Met en diferentes estadios histológicos de lesiones de SK-C y SK-SIDA, observando que la intensidad de tinción de c-Met fue mayor en los tumores que en las placas, de forma que el HGF se comporta como un factor de progresión en el SK.EL HHV-8, el factor etiológico del SK, codifica la v-ciclina, que formando complejo con la cinasa dependiente de ciclina (CDK) 6, contribuye a la fosforilación y degradación mediada por proteasoma del inhibidor de las cinasas dependientes de ciclina p27KIP1. La p27KIP1 regula negativamente la proliferación celular uniéndose e inhibiendo a los complejos ciclina-CDK de fase G1. Por otro lado, la infrarregulación de la expresión de la p27KIP1 parece facilitar el desarrollo tumoral y la diseminación metastásica; por ello la p27KIP1 ha sido considerada como un factor pronóstico independiente en una gran variedad de neoplasias humanas. Aunque la naturaleza neoplásica del SK todavía es controvertida, se ha demostrado repetidas veces que en algunos pacientes el SK puede comportarse como una neoplasia maligna y seguir un curso ominoso. Para determinar si la disminución de los niveles de la p27KIP1 está también relacionada con un comportamiento más agresivo del SK, decidimos investigar la inmunoreactividad de la p27KIP1 en biopsias de SK. De este modo, intentamos determinar si la disminución de los niveles de expresión de la p27KIP1 está relacionada con la afectación extracutánea en el SK, como ocurre en otras neoplasias cuando metastatizan. La media de porcentajes de células positivas para p27KIP1 era significativamente mayor en las biopsias de lesiones cutáneas y en las máculas-placas que en las lesiones extracutáneas y en los tumores respectivamente. Estos resultados apoyan la hipótesis de que la disminución de los niveles de la p27KIP1, que pueden ser producidos por la infección por el HHV-8, facilitan la progresión del SK a través de sus estadios histopatológicos y su eventual extensión extracutáneaEstudios recientes han demostrado que la degradación de la p27KIP1 a través de la vía ubicuitin-proteasoma está mediada por el complejo SCF/ p45SKP2 y por su receptor específico de sustrato F-box p45SKP2. La p45SKP2 está frecuentemente sobreexpresada en células transformadas, induce la fase S en células quiescentes y se sospecha que es un protooncogen en tumores humanos. De hecho, se ha determinado una asociación entre el incremento de los niveles de la p45SKP2 y la disminución de los niveles de la p27KIP1 en neoplasias epiteliales. Hemos estudiado si la expresión de la p45SKP2 está alterada en las lesiones agresivas del SK y su relación con la infrarregulación de la p27KIP1, sexo e infección por el VIH. La sobreexpresión nuclear de la p45SKP2 estaba presente en todos los estadios del SK, estando significativamente incrementada en los tumores cutáneos y en las lesiones extracutáneas en comparación con la máculas y placas. No se identificaron diferencias estadísticamente significativas en relación con el sexo y estatus VIH de los pacientes, y el análisis de regresión no mostró correlación entre la p45SKP2 y la p27KIP1. Estos hallazgos sugieren que la p45SKP2 está involucrada en el SK, no sólo promoviendo la degradación de la p27KIP1, sino también a través de otros mecanismos todavía desconocidos. / Kaposi's sarcoma (KS) is an angioproliferative disease with four clinical-epidemiological forms: classic (C-KS), African-endemic, immunosuppressive drug-related and acquired immune deficiency syndrome-related (AIDS-KS). KS involvement is usually limited to the skin, but in aggressive cases it may disseminate to extracutaneous locations. In the skin, lesions are clinicopathologically classified into macules, plaques and tumours in agreement with their progression in severity. KS seems to begin as a reactive vascular proliferation due to an unbalanced cytokine network, whereas in advanced stages, it behaves as a multifocal neoplasm.The different biological behavior of KS according to its epidemiological presentations and stages might be related to the presence of specific alterations in the mechanisms controlling tumor growth and development, such as cytokine or angiogenic growth factor overstimulation or alterations of the oncoprotein networks that control cell proliferation and apoptosis. These alterations would provide neoplastic stimuli for the development, progression, and aggressive behaviour of KS. Hepatocyte growth factor (HGF) is a pleiotropic angiogenic cytokine that is overexpressed in invasive human cancers and may function as a tumor progression factor, stimulating tumour cell invasiveness and angiogenesis. These responses are transduced through the c-Met receptor. HGF stimulates proliferation of spindle cells cultured from human KS lesions, and KS cells synthesize and secrete HGF and express c-Met, thus providing an autocrine loop for tumour proliferation and neovascularization. We have studied the expression of c-Met in different histological stages of AIDS-associated and classic KS lesions. The staining intensity of c-Met was stronger in tumours than in plaques showing that HGF would be a progression factor in KS. HHV-8, the KS'etiologic factor, encoded v-cyclin, through its complexing with cyclin-dependent kinase (CDK) 6, contributes to the phosphorylation and proteasome-mediated degradation of p27KIP1, a cyclin-dependent kinase inhibitor. P27KIP1 regulates negatively cell proliferation by binding and inhibiting G1 cyclin-CDK complexes. On the other hand, down-regulation of p27KIP1 expression seems to facilitate tumour development and metastatic dissemination; then p27KIP1 has been considerated as an independent prognostic factor in a variety of human neoplasms. Although the neoplastic nature of KS remains controversial, it has been repeatedly demonstrated that in some patients KS may behave as a malignant neoplasm and follow an ominous course. To determine whether decreased p27KIP1 levels are also related to more aggressive behaviour in KS, it was decided to investigate p27KIP1 immunoreactivity in KS biopsy specimens. Thereby, we sought to determine whether the decrease in p27KIP1 expression levels is related to extracutaneous involvement in KS, as is the case in several other types of neoplasms when they metastasize. The mean percentages of p27KIP1-positive cells were significantly higher in biopsy specimens from skin lesions and in macules-plaques than in those from extracutaneous locations and tumours respectively. These results lend support to the hypothesis that decreased levels of p27KIP1, which may have been brought about by HHV-8 infection, play a role in KS progression through its various histopathological stages, to its eventual extracutaneous spread.Recent studies have demonstrated that p27KIP1 degradation through the ubiquitin-proteasome pathway is mediated by the SCF/p45SKP2 complex and by the substrate-specific receptor of this complex, the F-Box protein p45SKP2. P45SKP2 is frequently over-expressed in transformed cells, induces S phase in quiescent cells and is a suspected proto-oncogene in human tumours. In fact, there are recent reports of increased levels of p45SKP2 in association with reduced p27KIP1 levels in epithelial neoplasms. We have studied of whether p45SKP2 expression is altered in aggressive lesions of KS and its relation to p27KIP1 down-regulation, gender and HIV infection. P45SKP2 nuclear over-expression was present in all KS stages, being significantly increased in skin tumours and extracutaneous lesions as compared with macules and plaques. No statistically significant differences were found in regard to patients´ sex and HIV status and regression analysis failed to show a correlation among p45SKP2 and p27KIP1. These findings suggest that p45SKP2 is involved in KS, not only by promoting the degradation of p27KIP1 but also through other mechanisms still unknown.

Yes / It has been shown previously that cancer cells with an activated oncogenic pathway, including Met activation, require Ran for growth and survival. Here, we show that knockdown of Ran leads to a reduction of Met receptor expression in several breast and lung cancer cell lines. This, in turn suppressed HGF expression and the Met-mediated activation of the Akt pathway, as well as cell adhesion, migration, and invasion. In a cell line model where Met amplification has previously been shown to contribute to gefitinib resistance, Ran knockdown sensitized cells to gefitinib-mediated inhibition of Akt and ERK1/2 phosphorylation and consequently reduced cell proliferation. We further demonstrate that Met reductionmediated by knockdown of Ran, occurs at the post-transcriptional level, probably via a matrix metalloproteinase. Moreover, the level of immunoreactive Ran and Met are positively associated in human breast cancer specimens, suggesting that a high level of Ran may be a prerequisite for Met overexpression. Interestingly, a high level of immunoreactive Ran dictates the prognostic significance of Met, indicating that the co-overexpression of Met and Ran may be associated with cancer progression and could be used in combination as a prognostic indicator. / The authors would like to thank Cancer Research UK for the post-doctoral fellowship to H.F.Y.

Orientadores: Laura Sterian Ward, Antônio Hugo José Fróes Marques Campos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T01:02:11Z (GMT). No. of bitstreams: 1 Rocha_AngelicaGomes_M.pdf: 1644333 bytes, checksum: e3503fb6e2c8209f7a6696df111d6a78 (MD5) Previous issue date: 2014 / Resumo: Marcadores de malignidade, especialmente capazes de distinguir lesões de padrão folicular, que sejam de fácil implantação na rotina do diagnóstico de nódulos tireoidianos, continuam sendo extremamente necessários, dado o crescente aumento de nódulos tireoidianos diagnosticados nos últimos anos. A via HGF/c-Met/STAT3 está relacionada com desenvolvimento e progressão tumoral, sendo que a expressão de c-Met, HGF e de STAT3 foram descritas em grande parte dos carcinomas papilíferos de tireoide (CPT), mas não em tecido tireoidiano normal, sugerindo sua relação com o desenvolvimento e progressão do CPT. Para avaliar a utilidade da expressão proteica de c-Met, HGF, STAT3, e de sua proteína fosforilada (pSTAT3) no diagnóstico e no prognóstico de pacientes com nódulos tireoidianos, analisamos 356 tecidos tireoidianos, sendo 153 carcinomas papilíferos (CPT), dos quais 95 eram clássicos (CPC), 47 carcinomas papilíferos variante folicular (CPVF), e 11 carcinomas papilíferos de células altas (CPCA); 34 carcinomas foliculares (CFT), 34 adenomas foliculares (AF), 124 bócios e 11 tecidos normais. Todos os pacientes foram tratados e acompanhados de acordo com um mesmo protocolo padrão por 1-10 anos (Mo=5 anos). Áreas representativas do tecido foram selecionadas para a construção de uma lâmina de tissue microarray (TMA) que foi submetida à técnica de imunoistoquímica e analisada pelo score de Allred. A expressão citoplasmática de c-Met foi capaz de diferenciar nódulos malignos de benignos (p<0,0001, sensibilidade 86%, especificidade 76%, VPP 77%, VPN 86%); CPT de CF (p=0,0003, sensibilidade 96%, especificidade 31%, VPP 87%, VPN 63%); variante folicular de CPT de CF (p=0,0232 sensibilidade 93%, especificidade 31%, VPP 66%, VPN 77%); assim como variante folicular de CPT de AF (p=0,0003, sensibilidade 93%, especificidade 50%, VPP 68%, VPN 87%). Além disso, a expressão de c-Met se correlacionou com tireoidite (p<0,0001) e multifocalidade (p=0,0028), mas não com presença de cápsula, invasão, tamanho do tumor, estadiamento TNM, e presença de metástase no diagnóstico e na evolução. A expressão nuclear de STAT3 diferenciou os nódulos benignos dos malignos (p<0,0001, sensibilidade 83%, especificidade 74%, VPP 75%, VPN 83%); CF de AF (p=0,0457, sensibilidade 80%, especificidade 52%, VPP 65%, VPN 71%); bócios de CPT variante folicular (p<0,001, sensibilidade 89%, especificidade 65%, VPP 91%, VPN 60%); bócio de CF (p<0,0001, sensibilidade 89%, especificidade 80%, VPP 95%, VPN 60%); bócio de AF (p=0,0005, sensibilidade 89%, especificidade 80%, VPP 95%, VPN 60%). Além disso, a expressão de STAT3 se correlacionou com tireoidite (p=0,0095) e multifocalidade (p<0,0001), mas não com presença de cápsula, invasão, tamanho do tumor, estadiamento TNM, e presença de metástase no diagnóstico e na evolução. A expressão de pSTAT3 e HGF não auxiliou no diagnóstico dos nódulos, e tampouco se correlacionou com características de agressividade dos tumores. Conclui-se que as proteínas c-Met e STAT3 podem ser consideradas marcadores clínicos úteis na rotina de laboratórios, uma vez que foram capazes de diferenciar os nódulos malignos dos benignos, alguns tipos histológicos dos nódulos, além de se correlacionarem com fatores de agressividade dos tumores / Abstract: Malignancy markers, especially the ones that are capable of distinguishing follicular lesions and with easy deployment in the routine diagnosis of thyroid nodules are much needed, given the increasing number of thyroid nodules in recent years. The HGF/c-Met/STAT3 pathway is related to the development and progression of many types of cancers, and c-Met, HGF and STAT3 expression were described in most papillary thyroid carcinomas (PTC), but not in normal thyroid tissue, suggesting it is related with the development and progression of PTC. To evaluate the usefulness of c-Met, HGF, STAT3, and its phosphorylated form (pSTAT3) protein expression in the diagnosis and prognosis of patients with thyroid nodules, we analyzed 356 thyroid tissues, including 153 papillary carcinomas (PTC), 95 classical type, 47 follicular variants of papillary carcinoma, and 11 tall cells carcinomas; 34 follicular carcinomas (FC), 34 follicular adenomas (FA), 124 goiters and 11 normal tissues. All patients were treated and monitored according to the same standard protocol for 1-10 years (Mo = 5 years). Representative tissue areas were selected for the construction of a tissue microarray (TMA) which was subjected to immunohistochemistry and analyzed by the Allred score. The cytoplasmic expression of c-Met was able to differentiate malignant from benign nodules (p <0.0001, sensitivity 86%, specificity 76%, PPV 77%, 86% NPV); PTC from FCT (p = 0.0003, sensitivity 96%, specificity 31%, PPV 87%, 63% NPV); follicular variant of PTC from FCT (p = 0.0232 sensitivity 93%, specificity 31%, PPV 66%, NPV 77%); as well as follicular variant of CPT from FA (p = 0.0003, sensitivity 93%, specificity 50%, PPV 68%, 87% NPV). Furthermore, c-Met expression was correlated to the presence of thyroiditis (p<0.0001) and multifocality (p=0.0028), but not with the presence of capsule, invasion, tumour size, TNM staging, and metastasis at diagnosis or evolution of the disease. The nuclear expression of STAT3 differentiated benign from malignant nodules (p <0.0001, sensitivity 83%, specificity 74%, PPV 75%, NPV 83%); FCT from FA (p = 0.0457, sensitivity 80%, specificity 52%, PPV 65%, NPV 71%); goiter follicular variant of PTC (p <0.001, sensitivity 89%, specificity 65%, PPV 91%, 60% NPV); goiter from FCT (p <0.0001, sensitivity 89%, specificity 80%, PPV 95%, NPV 60%); goiter from FA (p = 0.0005, sensitivity 89%, specificity 80%, PPV 95%, NPV 60%). In addition, STAT3 expression was associated with thyroiditis (p=0.0095) and multifocality (p<0.0001), but not with the presence of capsule, invasion, tumour size, TNM staging, and metastasis at diagnosis or evolution of the disease. The expression of pSTAT3 and HGF did not help the diagnostic of nodules and was not correlated with any tumour characteristic of aggressiveness. We concluded that c-Met and STAT3 could be useful as molecular markers in laboratory routine, helping to differentiate malignant from benign nodules, and some histological types of nodules, and was also associated with some tumour characteristics of aggressiveness / Mestrado / Ensino em Saúde / Mestra em Clínica Médica