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 mitochondrialSIRT3 modulates several biologicalpathways suchas cancer, metabolism, and hypoxia-related diseases. Recently, wediscovered new 1,4-dihydropyridines, compounds 2 and 3, the latter being a SIRT3-specific activator. In the presentwork, a novel 2- and 3-related small seriesof compounds have been developed, with 3c displayingthe strongest SIRT3 binding and activation, with a K (D) of 29 & mu;M and 387% of enzyme activation. Differently, 3d was the best in enhancing glutamate dehydrogenase activityand deacetylating K68- and K122-acMnSOD in triple-negative MDA-MB-231breast cancer cells. Tested in CAL-62 thyroid cancer and MDA-MB-231cells, 3d displayed the strongest time- and dose-dependentreduction of cell viability and clonogenicity at a single-digit micromolarlevel, along with cell death, in both normoxia and hypoxia conditions.Moreover, 3d downregulated not only hypoxia-induced factors,such as HIF-1 & alpha;, EPAS-1, and CA-IX, but also epithelial-mesenchymaltransition master regulators and extracellular matrix components suchas SNAIL1, ZEB1, SLUG, COL1A2, MMP2, and MMP9, markedly hamperingMDA-MB-231 cell migration.