A proteomic study of the dual oncogenic and tumor- suppressive roles of SIRT3 in lung and breast cancer cell lines

Mitochondria play a crucial role in metabolism and energy production by generating adenosine triphosphate (ATP) through oxidative phosphorylation. They also help maintain intracellular calcium levels, facilitate communication between the nucleus and cytoplasm, detoxify reactive oxygen species (ROS), and regulate apoptosis (programmed cell death). Reversible acetylation of mitochondrial proteins is a key post-translational modification influencing these processes, with the NAD⁺-dependent deacetylase SIRT3 being a major regulator. While SIRT3 has been described as a tumor suppressor in some contexts and as a tumor promoter in others, its role appears to be tissue- and metabolism-specific. Here, we compared the proteomic and acetylomic responses of lung adenocarcinoma (A549) and breast adenocarcinoma (MCF7) cell lines to SIRT3 inhibition by 3-(1H-1,2,3-triazol-4-yl)pyridine (3-TYP). The two lines were selected based on distinct metabolic phenotypes and reported differences in basal SIRT3 abundance. Total proteome and mitochondrial-enriched fractions were analyzed separately for each cell line to avoid cross-line normalization bias. We identified 6,457 proteins and 4,199 acetylated peptides, revealing divergent pathway enrichments and acetylation patterns following SIRT3 inhibition. A549 cells showed enrichment of oxidative metabolism pathways, whereas MCF7 cells exhibited features consistent with metabolic reprogramming. These findings suggest that the cellular context determines the proteomic consequences of SIRT3 modulation and highlight the importance of metabolism in shaping SIRT3-associated phenotypes.