Page 71 - SDIR5 Abstract book 21 12 2021.

POSTER PRESENTATIONS

P31

Combination of sirtuin 3 and hyperoxia diminishes tumorigenic properties of MDA-MB-231
cells

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Iva I. Podgorski , Marija Pinterić , Dora Marčinko , Marijana Popović Hadžija , Vedrana Filić , Ivan
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Ciganek , Denis Pleše , Tihomir Balog , Sandra Sobočanec
1 Division of Molecular Medicine, Ruđer Bošković Institute, Zagreb, Croatia
2 Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia

Background: Since the role of the major mitochondrial NAD+-dependent deacetylase, sirtuin 3 (Sirt3), is
differential in cancer, opposite to the well-known tumor-suppressing effect of hyperoxia, this study aimed
to investigate the role of Sirt3 in triple-negative breast cancer (TNBC) cell line MDA-MB-231 upon hyperoxic
(95% O2) conditions. Material and methods: MDA-MB-231 cells were stably transfected with Flag-tagged
Sirt-3 or empty plasmid. Western blot and real-time PCR were used to monitor the expression of proteins
or genes involved in mitochondrial biogenesis, metabolic regulation and antioxidant defense.
Immunocytochemistry and confocal microscopy were used to confirm the cellular localization and
abundance of proteins. Flow cytometry was used to analyze mitochondrial mass, potential and ROS
production, and MTT test as a measure of metabolic activity. Mitotic index analysis, colony-forming unit
assay, DNA damage and Annexin V-FITC analyses were used to assess the differences in the growth and
apoptosis rate. Results: Although Sirt3 seemed to improve mitochondrial properties by increasing
mitochondrial mass and potential, metabolic activity (Warburg effect) and antioxidative defence (SOD2,
Cat), it also increased mitochondrial ROS, induced DNA damage, timp-1 expression, formation of
multinucleated cells and apoptosis, and finally markedly reduced the proliferation of MDA-MB-231 cells.
All these effects were even more evident upon the hyperoxic treatment, thus pointing towards combined
negative effect of Sirt3 and hyperoxia on MDA-MB-231 cells. Conclusion: Both Sirt3 and hyperoxia, alone
or in combination, have the potential to negatively affect the malignant properties of the MDA-MB-231
cells and should be further explored as a possible therapy for TNBC.
Keywords: breast cancer, hyperoxia, MDA-MB-231, oxidative stress, sirtuin 3

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