Publicação
Establishment of a Glioblastoma Zebrafish Xenograft Model
| Resumo: | Glioblastoma multiforme (GBM) is the most common and lethal primary brain tumor. Despite years of research, patients’ prognosis is still very poor. The current therapeutic options are scarce and consist of surgery, radiotherapy and chemotherapy with Temozolomide (TMZ). Immunotherapy holds promise in treating GBM, however the particular immunosuppressive microenvironment of GBM constitutes a major challenge. Not only is it urgent to find new approaches but also to predict which patients will benefit or not from the available therapies. Recently, my host laboratory has shown that zebrafish xenografts can reveal different therapeutic responses and are suited to study cancer hallmarks such as angiogenesis, metastasis and the innate tumor microenvironment (TME). The present project had the major goal of developing a glioblastoma zebrafish xenograft model, as a first step towards a future personalized approach in glioblastoma. Using a human glioblastoma cell line, U87MG, I generated subcutaneous (PVS) and orthotopic (brain) zebrafish xenografts. Tumor hallmarks and treatment response were analyzed by single-cell confocal imaging. We also screened the major therapeutic options present in the guidelines and showed that U87MG-GBM orthotopic xenografts show sensitivity to all therapies. However, the combination of radiotherapy and TMZ was the most efficient. Characterization of the TME revealed a prevalence of a pro-tumoral environment (M2-like macrophages) and reduced infiltration of neutrophils in the brain. Finally, we challenged our model with pembrolizumab immunotherapy and showed a significant induction of cell death and tumor shrinkage in a non-cell autonomous manner. Pembrolizumab treatment led to drastic decrease in macrophage recruitment. Since macrophages have been shown to be crucial for tumor survival and maintenance, we suggest that pembrolizumab mechanism of action can rely on impairment on macrophage infiltration. |
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| Autores principais: | Fontes, Márcia Catarina Oliveira |
| Assunto: | glioblastoma xenógrafos de peixe-zebra microambiente tumoral quimioterapia pembrolizumab Teses de mestrado - 2022 |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Glioblastoma multiforme (GBM) is the most common and lethal primary brain tumor. Despite years of research, patients’ prognosis is still very poor. The current therapeutic options are scarce and consist of surgery, radiotherapy and chemotherapy with Temozolomide (TMZ). Immunotherapy holds promise in treating GBM, however the particular immunosuppressive microenvironment of GBM constitutes a major challenge. Not only is it urgent to find new approaches but also to predict which patients will benefit or not from the available therapies. Recently, my host laboratory has shown that zebrafish xenografts can reveal different therapeutic responses and are suited to study cancer hallmarks such as angiogenesis, metastasis and the innate tumor microenvironment (TME). The present project had the major goal of developing a glioblastoma zebrafish xenograft model, as a first step towards a future personalized approach in glioblastoma. Using a human glioblastoma cell line, U87MG, I generated subcutaneous (PVS) and orthotopic (brain) zebrafish xenografts. Tumor hallmarks and treatment response were analyzed by single-cell confocal imaging. We also screened the major therapeutic options present in the guidelines and showed that U87MG-GBM orthotopic xenografts show sensitivity to all therapies. However, the combination of radiotherapy and TMZ was the most efficient. Characterization of the TME revealed a prevalence of a pro-tumoral environment (M2-like macrophages) and reduced infiltration of neutrophils in the brain. Finally, we challenged our model with pembrolizumab immunotherapy and showed a significant induction of cell death and tumor shrinkage in a non-cell autonomous manner. Pembrolizumab treatment led to drastic decrease in macrophage recruitment. Since macrophages have been shown to be crucial for tumor survival and maintenance, we suggest that pembrolizumab mechanism of action can rely on impairment on macrophage infiltration. |
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