AbstractsBiology & Animal Science

Metastasis represents the most life-threatening aspect of tumorigenesis and is the leading cause of death by cancer. Intensive research in this field has shed light on some of the molecular strategies employed by the heterogeneous cancer cell populations to leave the primary tumor, disseminate and grow new colonies in distant organs. In any given tumor, one important functional category of cancer cells is represented by cancer stem cells (CSCs), endowed with self-renewal and tumor-initiating potentials. Moreover, the epithelial-mesenchymal transition (EMT) program represents a process of fundamental importance conducive to tumor dissemination and metastatic spread of cancer cells. Some studies have pointed out that the EMT is responsible for the acquisition of the CSC-like state whereas others have shown that both cell entities can exist separately and cooperate to accelerate the process of metastasis. Here, we propose the combined use of metabolomics and fluxomics strategies to shed light on the metabolic reprogramming and vulnerabilities accompanying specific cancer cell phenotypes that differs in their metastatic and invasive capacities. The main objective of this thesis is focused on the characterization of the metabolic reprogramming and vulnerabilities of uncoupled CSC and EMT phenotypes present in a dual-cell prostate cancer cell model and represented by the highly related cell subpopulations PC-3M and PC-3S cells, respectively. Our results indicated that epithelial PC-3M cells, displaying CSC features and a high metastatic potential, preferentially rely on aerobic glycolysis (Warburg effect) for bioenergetics. Although these cells show low coupling between glycolysis and oxidative phosphorylation (OXPHOS) because of low pyruvate dehydrogenase activity, they display an increased metabolic flexibility to utilize different carbon sources, such as fatty acids, glutamine and other amino acids, that offset the decreased diversion of glucose-derived carbons into the tricarboxylic acid cycle and OXPHOS. The characterization of the non-CSC mesenchymal PC-3S cells expressing the EMT program and endowed with a high invasive capacity, showed a strong coupling between aerobic glycolysis and OXPHOS and a strong dependence on the mitochondrial metabolism for bioenergetics, which leads to higher levels of ROS that require increased levels of glutathione to provide an adequate antioxidant defense system. PC-3M and PC-3S cells differentially reprogram the use of the oxidative and non-oxidative branches of the pentose phosphate pathway to sustain their distinct metabolic needs. Glycolytic intermediates are preferentially directed to ribose synthesis in PC-3M cells to build up nucleotides whereas the generation of NADPH is more crucial for PC-3S cells to counteract their higher oxidative stress and sustain their increased fatty acid synthesis. Glutamine metabolism substantially contributes to TCA reactions in PC-3. For PC-3S cells, both glucose and glutamine are necessary to display a proper mitochondrial function. PC-3M…