Publicação
The influence of cancer cell metabolism and microenvironment on tumour progression and drug resistance
| Resumo: | In the last years a new revival interest has been demonstrated in the reprogrammed metabolism of cancer cells. Described by Otto Warburg, the altered metabolism characterized mainly by a high dependence on lactic acid fermentation, even in the presence of oxygen, is an emergent hallmark of cancer cells. The increase of the glycolytic flux induces a high acidity of the extracellular space, maintained by overexpression of different pH regulators at the plasma membrane, and enhances the more aggressive characteristics of tumour cells, such as increased migration and invasion abilities and resistance to therapy. Therefore, the altered metabolism can be an excellent target for the development of new therapies in cancer field. The reverse pH gradient establish an interplay between cancer metabolism and the surrounding environment. Furthermore, the ablation of pH regulation on cancer cells can be a second way to overcome the major obstacle in antitumour therapy, the multidrug resistance. This phenotype is identified in other cell population that reside inside a tumour mass, beside the tumour parenchymal cells, the cancer stem cells (CSCs), the main responsible for tumour relapse. Recently, it has been described that the reprogrammed metabolism is an emergent target to eliminate this tumour population and to increase the survival rates in many different types of cancer. However, new efforts are needed to improve the knowledge obtained until now on this cancer hallmark. For that reason, this work aims to study and characterize the role of reprogrammed metabolism in different types of cancer, gliomas and pancreatic ductal adenocarcinoma (PDAC) cells and the derived CSCs. Additionally, we aimed to study how this altered phenotype can be modulated, using bioenergetic modulators (BMs), combined or not with conventional drugs. The metabolic profile of the different cell lines was analysed through quantification of lactate production, glucose consumption and intracellular ATP. Concerning the inhibition of the main energetic pathways, it was performed using the glycolytic inhibitors dichloroacetate (DCA), 2-deoxy-D-glucose (2-DG) and the OXPHOS inhibitor and antidiabetic drug, phenformin. All BMs induced a decrease in tumour cell proliferation, and when combined with the conventional antitumour drugs, temozolomide (TMZ) in case of glioma cells, and paclitaxel albumin nanoparticles (NAB-PTX) for pancreatic cancer cells, an increase of drug cytotoxicity was found. Furthermore, when using an in vivo glioma model, the chicken chorioallantoic membrane, all BMs showed an elevated specificity targeting only tumour cells. Additionally, all BMs, namely the glycolytic inhibitors, induced an altered metabolic profile and decrease in migration and invasion abilities in glioma cells. Regarding pancreatic cancer cells, we observed a higher dependence on glycolysis for both cell lines in 2D cell culture. In CSCs, this metabolic profile was more evident in 3D conditions, when an extracellular matrix with higher percentage of collagen was used. Additionally, we verified that the BMs affected the metabolic behaviour of both cell lines. For the parenchymal cells, glycolysis and OXPHOS were important in PANC-1 cell proliferation, but the effect was dependent of the growth substrate. CSCs presented a very complex pattern, showing metabolic plasticity, where inhibition of one pathway can be compensated by others. For instance, it was verified that the CSCs redirected their metabolism to glycolysis as the main energy source, when OXPHOS was inhibited by phenformin. The combination of NAB-PTX with BMs decreased cell proliferation and increased cell death, namely for phenformin in CSCs. The second objective was to unravel the role of the pH regulators, in cancer characteristics. The hyper-glycolytic acid-resistant phenotype has been described in many type of cancers, namely in breast cancer, the other model used in this work. For that, the expression of pH regulators was evaluated both in breast cancer clinical samples and breast cancer cell lines. We observed an overexpression of these proteins, indicating that they can be used as predictive biomarkers in breast cancer diagnosis. Specific inhibitors for these proteins were used and the main characteristics of tumour cells were evaluated. All the compounds decreased cell viability as well as, the migration and invasion abilities of cancer cells. Furthermore, when combined with the conventional drug, doxorubicin, one of the first line drugs used in breast cancer chemotherapeutic regimens, a synergistic effect we observed. To conclude, this study suggests that tumour metabolism behaves as a mediator between tumour cells and the tumour microenvironment, being an important player in tumourigenesis and in the aggressive phenotype of cancer cells. Thus, blockage of the main players involved in this relationship, can disrupt the mechanism responsible for treatment failure in these three types of cancers and improve the existent therapeutic options used in clinical practice. |
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| Autores principais: | Valente, Diana Maria Tavares |
| Assunto: | Tumour metabolism Tumour microenvironment Bioenergetic modulators pH regulators Metabolismo do cancro Microambiente tumoral Moduladores bioenergéticos Reguladores de pH |
| Ano: | 2018 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | In the last years a new revival interest has been demonstrated in the reprogrammed metabolism of cancer cells. Described by Otto Warburg, the altered metabolism characterized mainly by a high dependence on lactic acid fermentation, even in the presence of oxygen, is an emergent hallmark of cancer cells. The increase of the glycolytic flux induces a high acidity of the extracellular space, maintained by overexpression of different pH regulators at the plasma membrane, and enhances the more aggressive characteristics of tumour cells, such as increased migration and invasion abilities and resistance to therapy. Therefore, the altered metabolism can be an excellent target for the development of new therapies in cancer field. The reverse pH gradient establish an interplay between cancer metabolism and the surrounding environment. Furthermore, the ablation of pH regulation on cancer cells can be a second way to overcome the major obstacle in antitumour therapy, the multidrug resistance. This phenotype is identified in other cell population that reside inside a tumour mass, beside the tumour parenchymal cells, the cancer stem cells (CSCs), the main responsible for tumour relapse. Recently, it has been described that the reprogrammed metabolism is an emergent target to eliminate this tumour population and to increase the survival rates in many different types of cancer. However, new efforts are needed to improve the knowledge obtained until now on this cancer hallmark. For that reason, this work aims to study and characterize the role of reprogrammed metabolism in different types of cancer, gliomas and pancreatic ductal adenocarcinoma (PDAC) cells and the derived CSCs. Additionally, we aimed to study how this altered phenotype can be modulated, using bioenergetic modulators (BMs), combined or not with conventional drugs. The metabolic profile of the different cell lines was analysed through quantification of lactate production, glucose consumption and intracellular ATP. Concerning the inhibition of the main energetic pathways, it was performed using the glycolytic inhibitors dichloroacetate (DCA), 2-deoxy-D-glucose (2-DG) and the OXPHOS inhibitor and antidiabetic drug, phenformin. All BMs induced a decrease in tumour cell proliferation, and when combined with the conventional antitumour drugs, temozolomide (TMZ) in case of glioma cells, and paclitaxel albumin nanoparticles (NAB-PTX) for pancreatic cancer cells, an increase of drug cytotoxicity was found. Furthermore, when using an in vivo glioma model, the chicken chorioallantoic membrane, all BMs showed an elevated specificity targeting only tumour cells. Additionally, all BMs, namely the glycolytic inhibitors, induced an altered metabolic profile and decrease in migration and invasion abilities in glioma cells. Regarding pancreatic cancer cells, we observed a higher dependence on glycolysis for both cell lines in 2D cell culture. In CSCs, this metabolic profile was more evident in 3D conditions, when an extracellular matrix with higher percentage of collagen was used. Additionally, we verified that the BMs affected the metabolic behaviour of both cell lines. For the parenchymal cells, glycolysis and OXPHOS were important in PANC-1 cell proliferation, but the effect was dependent of the growth substrate. CSCs presented a very complex pattern, showing metabolic plasticity, where inhibition of one pathway can be compensated by others. For instance, it was verified that the CSCs redirected their metabolism to glycolysis as the main energy source, when OXPHOS was inhibited by phenformin. The combination of NAB-PTX with BMs decreased cell proliferation and increased cell death, namely for phenformin in CSCs. The second objective was to unravel the role of the pH regulators, in cancer characteristics. The hyper-glycolytic acid-resistant phenotype has been described in many type of cancers, namely in breast cancer, the other model used in this work. For that, the expression of pH regulators was evaluated both in breast cancer clinical samples and breast cancer cell lines. We observed an overexpression of these proteins, indicating that they can be used as predictive biomarkers in breast cancer diagnosis. Specific inhibitors for these proteins were used and the main characteristics of tumour cells were evaluated. All the compounds decreased cell viability as well as, the migration and invasion abilities of cancer cells. Furthermore, when combined with the conventional drug, doxorubicin, one of the first line drugs used in breast cancer chemotherapeutic regimens, a synergistic effect we observed. To conclude, this study suggests that tumour metabolism behaves as a mediator between tumour cells and the tumour microenvironment, being an important player in tumourigenesis and in the aggressive phenotype of cancer cells. Thus, blockage of the main players involved in this relationship, can disrupt the mechanism responsible for treatment failure in these three types of cancers and improve the existent therapeutic options used in clinical practice. |
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