Novel 1,4-Dihydropyridines as Specific Binders and Activators of SIRT3 Impair Cell Viability and Clonogenicity and Downregulate Hypoxia-Induced Targets in Cancer Cells

The mitochondrial
SIRT3 modulates several biological
pathways such
as cancer, metabolism, and hypoxia-related diseases. Recently, we
discovered new 1,4-dihydropyridines, compounds 2 and 3, the latter being a SIRT3-specific activator. In the present
work, a novel 2- and 3-related small series
of compounds have been developed, with 3c displaying
the strongest SIRT3 binding and activation, with a KD of 29 μM and 387% of enzyme activation. Differently, 3d was the best in enhancing glutamate dehydrogenase activity
and deacetylating K68- and K122-acMnSOD in triple-negative MDA-MB-231
breast cancer cells. Tested in CAL-62 thyroid cancer and MDA-MB-231
cells, 3d displayed the strongest time- and dose-dependent
reduction of cell viability and clonogenicity at a single-digit micromolar
level, along with cell death, in both normoxia and hypoxia conditions.
Moreover, 3d downregulated not only hypoxia-induced factors,
such as HIF-1α, EPAS-1, and CA-IX, but also epithelial–mesenchymal
transition master regulators and extracellular matrix components such
as SNAIL1, ZEB1, SLUG, COL1A2, MMP2, and MMP9, markedly hampering
MDA-MB-231 cell migration.