ACYL-COA SYNTHETASE 4 MODULATES MITOCHONDRIAL FUNCTION AND METABOLISM IN BREAST CANCER CELLS.

BENZO, YANINA; PRADA, JESICA G.; DATTILO, MELINA A.; LOPEZ, PAULA F.; CASTILLO, ANA F.; MORI SEQUEIROS GARCIA, M. MERCEDES; RINGELMAN SANCHEZ, PAOLA; PODEROSO, CECILIA; MALOBERTI, PAULA M.

Congreso; LVIII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2022

Acyl- CoA synthetase 4 (ACSL4) is an enzyme that catalyzes acyl-CoA synthesis from long chain fatty acid, being arachidonic acid its preferred substrate. In breast cancer, ACSL4 promotes tumor aggressiveness by increasing migration, proliferation and invasion. In this context, there is evidence of dysregulation of mitochondrial function, mitochondrial mass and subcellular spatial organization in cancer. Also, it is known that alteration of energy metabolism allows tumor cells to survive and spread even in challenging conditions. In MCF-7 breast cancer cells, a previous bioinformatic analysis showed that ACSL4 overexpression could modulate mitochondrial master regulatory genes involved in energy and respiratory metabolism. The aim of this work is to determine whether mitochondrial function and metabolism are modulated by ACSL4 in breast cancer cells. For this purpose, mRNA levels of genes related to mitochondrial function such as NRF-1/2, UCP2 and ANT1 were evaluated in MCF-7 overexpressing ACSL4 cells by qPCR. mRNA levels of these genes were significantly increased by ACSL4 overexpression related to control cells.Moreover, protein levels of mitochondrial complex III, VDAC1 and nuclear NRF-1 were significantly increased by ACSL4 overexpression in MCF-7 cells with respect to control cells. Respiratory and glycolytic function were studied using the Seahorse XF Cell Mito Stress Test and GlycoStress Test respectively. We observed a significant increase in oxygen consumption rate and basal respiration, maximal respiration, proton leak and respiratory reserve capacity in MCF-7 cells overexpressing ACSL4.Glycolytic function analysis demonstrated a significant increase in several parameters induced by ACSL4 such as extra acidification rate, non-glycolytic acidification, glycolysis and glycolytic capacity. On the other hand, results showed a significant decrease in the percentage of glycolytic reserve in MCF-7 overexpressing ACSL4. These results are consistent with the increase in mitochondrial activity induced by ACSL4 in this cellular model observed by MitotrackerRed staining. Mitochondrial mass was measured by MitotrackerGreen staining and analyzed by flow cytometry. Results showed a significant decrease of this parameter in MCF-7 cells that overexpress ACSL4 related to control cells. These results suggest that ACSL4 stimulates a greater mitochondrial turnover and a better response to high energy demand situations which in turn provides to the cells a greater capacity for invasion migration and proliferation. Thus, ACSL4 could not only confer an adaptive advantage to tumor cells by inducing glycolytic metabolism that favors tumor development but also could protect mitochondria against oxidative stress increasing antioxidant factors and promoting the expression of genes involved in mitochondrial biogenesis. Altogether, the results of this work extend the knowledge about the role of ACSL4 in respiration and mitochondrial function in breast cancer cells.