Exploring the cytotoxicity, uptake, cellular response, and proteomics of mono- and dinuclear DNA light-switch complexes

Drug resistance to platinum chemotherapeutics targeting DNA often involves abrogation of apoptosis, and has emerged as a significant challenge in modern, non-targeted chemotherapy. Consequently, there is great interest in the anti-cancer properties of metal complexes - particularly those that interact with DNA - and mechanisms of consequent cell death. Herein we compare a parent cytotoxic complex [Ru(phen)2(tpphz)]2+ [phen = 1,10-phenanthroline, tpphz = tetrapyridyl [3,2-a:2',3'-c:3'',2''-h:2''',3'''-j] phenazine], with a mononuclear analogue with modified intercalating ligand, [Ru(phen)2(taptp)]2+,[taptp = 4,5,9,18-tetraazaphenanthreno[9,10-b] triphenylene], and two structurally related di-nuclear, tpphz-bridged, heterometallic complexes, RuRe and RuPt. These changes result in a switch from intercalation to groove binding DNA interaction, concomitant reduction in cytotoxic potency, but no significant change in relative cytotoxicity toward platinum-resistant A2780CIS cancer cells, indicating that DNA interaction mode is not critical for the mechanism of platinum resistance. All variants exhibited a light-switch effect, which for the first time, was exploited to investigate timing of cell death by live cell microscopy. Surprisingly, cell death occurred rapidly as a consequence of oncosis, characterized by loss of cytoplasmic volume control, absence of significant mitochondrial membrane potential loss, and lack of activation of apoptotic cell death markers. Importantly, a novel, quantitative proteomic analysis of the A2780 cell genome following exposure to either mononuclear complex reveals changes in protein expression associated with global cell responses to oxidative stress, and DNA replication/repair cellular pathways. This combination of a multiple targeting modality and induction of a non-apoptotic death mechanism makes these complexes highly promising chemotherapeutic cytotoxicity leads

Polysulfide-triggered fluorescent indicator suitable for super-resolution microscopy and application in imaging

A new physiologically benign and cell membrane permeable BODIPY based molecular probe, MB-Sn, specifically senses intracellular hydrogen polysulfides (H2Sn, n > 1) localized in the endoplasmic reticulum. This reagent is suitable for mapping the intracellular distribution of H2Sn by wide-field as well as super-resolution Structured Illumination Microscopy (SIM)

Tracking HOCl concentrations across cellular organelles in real time using a super resolution microscopy probe

BODIPY derivative, SF-1, exclusively shows a fluorescence ON response to HOCl and images endogenously generated HOCl in RAW 264.7 macrophages. Widefield and super resolution structured illumination microscopy images confirm localization in the Golgi complex and lysosomes, and hence specifically detects HOCl generated in these organelles. SF-1 is compatible with 3D-SIM imaging of individual cells