Computational evidence for structural consequences of kiteplatin damage on DNA

A minimal structural variation can overcome tumour resistance of oxaliplatin: the case of 4,5-dehydrogenation of the cyclohexane ring

A new family of anticancer compounds has been derived from oxaliplatin by inserting a double-bond between carbons 4 and 5 of the 1,2-diaminocyclohexane ring. Testing against a panel of human tumour cell lines including cervical (A431), ovarian (2008), and colon carcinomas (HCT-15 and LoVo), and two oxaliplatin-resistant clones (LoVo OXP and LoVo MDR) has shown that the new compounds have, in general, equal if not better cytotoxic activity and are able to overcome the oxaliplatin-resistance. Moreover, the oxalato derivative induced lipid droplets increase in LoVo OXP cells thus suggesting the involvement of metabolism stress in its mechanism of action.

A new family of anticancer compounds has been derived from oxaliplatin by inserting a double-bond between carbons 4 and 5 of the 1,2-diaminocyclohexane ring.

Encapsulation of lipophilic kiteplatin Pt(iv) prodrugs in PLGA-PEG micelles

Biodegradable, PEG-coated, nanoparticles (NPs) have gained therapeutic application as injectable colloidal systems for the controlled and site-specific release of drugs. In this paper, encapsulation in PLGA-PEG polymer NPs has been exploited to lower the toxicity and to increase the antitumor activity of kiteplatin ([PtCl2(cis-1,4-DACH)]). Kiteplatin contains an isomeric form of the diamine ligand present in oxaliplatin and proved to be particularly active against ovarian and colon cancers. To favor encapsulation of the platinum drug in the hydrophobic core of the polymeric micelles, Pt(iv) prodrugs having hydrophobic carboxylic ligands at the axial positions were used in place of hydrophilic Pt(ii) complexes (compounds 1-4). The size, size distribution, and zeta potential (ZP) were measured by dynamic light scattering (DLS) and laser Doppler velocimetry (LDV), and drug encapsulation efficiency (EE) correlated to the alkyl chain length of the different Pt(iv) prodrugs. The number of the Pt atoms per NP (in the range of 1.3-2.4 × 10(6)) is comparable to that of polysilsesquioxane-based NPs and higher than that found for other nanoparticle platforms. The platinum-loaded PLGA-PEG NPs, tested in vivo in a syngeneic murine solid tumor (LLC), had a higher antitumor effect and, most importantly, were markedly less toxic than kiteplatin.

Combining the platinum(ii) drug candidate kiteplatin with 1,10-phenanthroline analogues

Drug candidate kiteplatin has been combined with analogues of 1,10-phenanthroline, and the DNA affinity and cytotoxicity have been assessed.

Cisplatin, Oxaliplatin, and Kiteplatin Subcellular Effects Compared in a Plant Model

The immediate visual comparison of platinum chemotherapeutics’ effects in eukaryotic cells using accessible plant models of transgenic Arabidopsis thaliana is reported. The leading anticancer drug cisplatin, a third generation drug used for colon cancer, oxaliplatin and kiteplatin, promising Pt-based anticancer drugs effective against resistant lines, were administered to transgenic A. thaliana plants monitoring their effects on cells from different tissues. The transgenic plants’ cell cytoskeletons were labelled by the green fluorescent protein (GFP)-tagged microtubule-protein TUA6 (TUA6-GFP), while the vacuolar organization was evidenced by two soluble chimerical GFPs (GFPChi and AleuGFP) and one transmembrane GFP-tagged tonoplast intrinsic protein 1-1 (TIP1.1-GFP). The three drugs showed easily recognizable effects on plant subcellular organization, thereby providing evidence for a differentiated drug targeting. Genetically modified A. thaliana are confirmed as a possible rapid and low-cost screening tool for better understanding the mechanism of action of human anticancer drugs.

Hydrogen abstraction by photoexcited benzophenone: consequences for DNA photosensitization

We report a computational investigation of the hydrogen abstraction (H-abstraction) induced by triplet benzophenone (³BP) on thymine nucleobase and backbone sugar.

Understanding DNA under oxidative stress and sensitization: the role of molecular modeling

DNA is constantly exposed to damaging threats coming from oxidative stress, i.e., from the presence of free radicals and reactive oxygen species. Sensitization from exogenous and endogenous compounds that strongly enhance the frequency of light-induced lesions also plays an important role. The experimental determination of DNA lesions, though a difficult subject, is somehow well established and allows to elucidate even extremely rare DNA lesions. In parallel, molecular modeling has become fundamental to clearly understand the fine mechanisms related to DNA defects induction. Indeed, it offers an unprecedented possibility to get access to an atomistic or even electronic resolution. Ab initio molecular dynamics may also describe the time-evolution of the molecular system and its reactivity. Yet the modeling of DNA (photo-)reactions does necessitate elaborate multi-scale methodologies to tackle a damage induction reactivity that takes place in a complex environment. The double-stranded DNA environment is first characterized by a very high flexibility, but also a strongly inhomogeneous electrostatic embedding. Additionally, one aims at capturing more subtle effects, such as the sequence selectivity which is of critical important for DNA damage. The structure and dynamics of the DNA/sensitizers complexes, as well as the photo-induced electron- and energy-transfer phenomena taking place upon sensitization, should be carefully modeled. Finally the factors inducing different repair ratios for different lesions should also be rationalized. In this review we will critically analyze the different computational strategies used to model DNA lesions. A clear picture of the complex interplay between reactivity and structural factors will be sketched. The use of proper multi-scale modeling leads to the in-depth comprehension of DNA lesions mechanisms and also to the rational design of new chemo-therapeutic agents.