Multifaceted anticancer mechanisms of tribenzyltin carboxylates: DNA minor groove targeting and inhibition of key enzymes in DNA replication, nucleotide synthesis, and redox homeostasis

Tribenzyltin carboxylates complexes, namely tri(4-fluorobenzyl)tin[(N,N-diisopropylcarbamothioyl)sulfanyl]acetate (C1) and tribenzyltin isonicotinate (C9), have been reported to exhibit significant anticancer activity via the death receptor and mitochondrial apoptotic pathway. However, understanding their upstream mechanism remains crucial. This study utilized both in silico and in vitro approaches to elucidate their mechanism of action. Molecular docking analysis indicated that C1 and C9 interacted with the minor groove of DNA. Fluorescence displacement assays confirmed their interaction with DNA through the minor groove. In enzyme inhibition assays, C1 showed significant inhibition of thioredoxin reductase (TrxR) activity, while C9 exhibited a dose-dependent effect, consistent with their docking affinities (- 4.1 and - 4.3 kcal/mol, respectively). Both compounds strongly inhibited human DNA topoisomerase I (TopI), supported by docking energies of - 7.0 and - 6.6 kcal/mol, respectively. The nearly complete inhibition of TopI across all treatment groups highlights it as a key molecular target. Additionally, C1 and C9 bound to thymidylate synthase (TS) with docking energies of - 7.2 and - 7.7 kcal/mol, respectively, leading to a marked reduction in TS levels. Molecular dynamics simulations of the TopI, TS, and TrxR complexes revealed that both C1 and C9 maintained stable binding within their respective active sites throughout the 100 ns trajectories. In summary, C1 and C9 primarily target the DNA minor groove and inhibit key enzymes such as TopI, TrxR, and TS, shedding light on their intricate mechanisms of action. These findings underscore the potential of C1 and C9 as promising multitarget metal-based anticancer agents.