Amoedo 2013 Abstract MiP2013
|Amoêdo ND, Rodrigues MF, Pereira S, Melo F, Jasiulionis M, Galina A, Rumjanek FD(2013) Comparative biochemistry of tumorigenesis: role of mitochondria in the metastatic process. Mitochondr Physiol Network 18.08.|
The classic bioenergetic phenotype of cancer cells of enhanced glycolysis was described by Otto Warburg approximately 90 years ago. However, the Warburg hypothesis does not necessarily imply mitochondrial dysfunction. Current thinking envisages tumor cells as compliant to an oxygen gradient within the tumor mass. Those cells on the periphery utilize oxygen whereas those found in hypoxic regions display metabolic symbiosis with the adjacent stromal cells . Essentially metabolic reprograming means up-regulation of pathways that increase the rate of ATP production, synthesis of lipids and redox balance. The process of carcinogenesis is guided by gene expression regulation that promote these metabolic changes in a different and complex way for each cancer cell, thus, the energy metabolism of cancer cells is very heterogeneous. For example, not all tumor cells display a high glycolytic flux as proposed by Warburg. Progression to metastasis appears to require mitochondrial function, a hypothesis that is compatible with the results obtained by our group.
In order to show this we resorted an experimental model of murine melanoma cells. A melanocyte cell line was subjected to several cycles of adhesion impediment, producing stable cell lines exhibiting phenotypes representing a progression from non-tumorigenic to metastatic cells. These were: non-tumorigenic cells melan-a (ma); non-tumorigenic cell line 4C (obtained after 4 cycles of adherence abrogation); non-metastatic 4C11- and metastatic 4C11+ melanoma cell lines. The metabolic profile of each of these different cell lines was investigated by evaluating enzyme activities and expression of members of the glycolytic and oxidative pathways .
Our results showed that only metastatic cell line (4C11+) released the highest amounts of lactate and exhibited high LDH activity related to glutamine catabolism. In contrast, high-resolution respirometry (HRR) showed that 4C11+ intact cells had increased (2.8-fold) oxidative metabolism, with enhanced (2.6-fold) oxygen flux coupled to ATP synthesis when compared to the other pre-malignant stages. Moreover, in 4C11+ cells, we observed an increase in succinate dehydrogenase (Complex II) activity confirmed by HRR in permeabilized cells. We did not observe an increase in mitochondrial content, mitochondrial biogenesis, but we observed an increase (2-fold) in fission process. These results suggest enhanced OXPHOS. This was thought to be associated to metastasis, a condition which would benefit from unrestricted supply of oxygen.
Detailed analysis of patterns in this and other models of tumor progression may reveal whether the modulation of the oxidative metabolism is a feature of the metastatic process. To test this hypothesis we produced 4C11+ Rho 0 cells. Preliminary results showed a decreased in proliferation.
• Keywords: Melanocyte, Melanoma
Labels: MiParea: Respiration, mt-Biogenesis;mt-density, mt-Structure;fission;fusion, mtDNA;mt-genetics Pathology: Cancer Stress:Ischemia-reperfusion Organism: Mouse Tissue;cell: Endothelial;epithelial;mesothelial cell, Other cell lines Preparation: Intact cells, Permeabilized cells, Enzyme Enzyme: Complex I, Complex II;succinate dehydrogenase, TCA cycle and matrix dehydrogenases Regulation: Aerobic glycolysis Coupling state: LEAK, ROUTINE, OXPHOS, ET Pathway: N, S, ROX HRR: Oxygraph-2k
1 - Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Brazil; 2 - Dept de Farmacologia, Universidade Federal de São Paulo, Brazil. - Email: email@example.com
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