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. 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-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 6457 proteins and 4199 acetylated peptides, revealing distinct pathway enrichments and acetylation changes after SIRT3 inhibition. A549 cells showed increased oxidative metabolism, while MCF7 cells exhibited metabolic reprogramming. These results indicate that the proteomic impact of SIRT3 modulation is strongly influenced by cellular metabolic context. All raw mass spectrometry data are publicly available in PXD063181.