The latency of peroxisomal catalase in terms of effectiveness factor for pancreatic and glioblastoma cancer cell lines in the presence of high concentrations of H2O2: Implications for the use of pharmacological ascorbate in cancer therapy

Pharmacological ascorbate combined with rucosopasem selectively radio-chemo-sensitizes NSCLC via generation of H2O2

Differences in cancer and normal cell oxidative metabolism provide a unique therapeutic opportunity for developing combined modality approaches with redox-active small molecules as radio-chemosensitizers that are well-tolerated by normal tissues. Pentaazamacrocyclic Mn (II)-containing (MnPAM) superoxide dismutase (SOD) mimetics and pharmacological ascorbate given IV to achieve [mM] plasma levels (pharmacological ascorbate: P-AscH‾) have been shown to act individually as cancer cell radio- and chemosensitizers via the generation of H2O2in vivo. The current study shows that the combination of newly developed MnPAM dismutase mimetic, rucosopasem manganese (RUC) with P-AscH‾ radio-sensitizes non-small cell lung cancer cells (NSCLC) and increases steady state levels of intracellular H2O2 with no additional toxicity to normal human bronchial epithelial cells (HBECs). Conditional over expression of catalase (CAT) in H1299T CATc15 cells demonstrates that the combination of RUC and P-AscH‾ causes radio-sensitization through an H2O2-dependent mechanism. Interestingly, RUC combined with P-AscH‾ demonstrates more than additive cytotoxicity in both H1299T and A549 NSCLC cells, but conditional over-expression of ferritin heavy chain (FtH) protected only the H1299T, and not the A549, from this toxicity. Most importantly, the combination of RUC + P-AscH‾ was found to sensitize both H1299T and A549 cell types to radio-chemotherapy with cisplatin (CIS) + etoposide (ETOP). Finally, in H1299T NSCLC xenografts the combination of RUC + P-AscH‾ with CIS + ETOP and 12 × 2 Gy radiation significantly inhibits tumor growth and increased median overall over survival. These results support the hypothesis that selective MnPAM dismutase mimetic + P-AscH‾ enhances the efficacy of radio-chemotherapy in NSCLC through a mechanism governed by redox active metals and H2O2 production.

Relevant Membrane Transport Proteins as Possible Gatekeepers for Effective Pharmacological Ascorbate Treatment in Cancer

Despite the increasing number of newly diagnosed malignancies worldwide, therapeutic options for some tumor diseases are unfortunately still limited. Interestingly, preclinical but also some clinical data suggest that the administration of pharmacological ascorbate seems to respond well, especially in some aggressively growing tumor entities. The membrane transport and channel proteins are highly relevant for the use of pharmacological ascorbate in cancer therapy and are involved in the transfer of active substances such as ascorbate, hydrogen peroxide, and iron that predominantly must enter malignant cells to induce antiproliferative effects and especially ferroptosis. In this review, the relevant conveying proteins from cellular surfaces are presented as an integral part of the efficacy of pharmacological ascorbate, considering the already known genetic and functional features in tumor tissues. Accordingly, candidates for diagnostic markers and therapeutic targets are mentioned.

Catalytic Oxygen Activation over the Defective CuO Nanoparticles for Ultrafast Dehalogenation

The nucleophilic superoxide radical (O₂^•-)-based dehalogenation reaction shows great potential to degrade the toxic halogenated organic compounds (HOCs). But such an O₂^•--mediated reductive reaction often suffers from the competition of the secondary oxidative species (e.g., •OH), leading to inferior electron efficiency and possible disinfection byproduct formation. Here, an O₂^•--dominant ultrafast dehalogenation system is developed via molecular O₂ activation by the oxygen vacancy (OV)-rich CuO nanoparticles (nCuO). The nCuO delivers a remarkable dechlorination rate constant of 3.92 × 10^-2 L min^-1 m^-2 for 2,4-dichlorophenol, much higher than that of the conventional zerovalent (bi)metals. The absorbed O₂ on the nCuO surface is exclusively responsible for O₂^•- generation, and its reactivity increases with the elevated OV content because of the enhanced orbital hybridization between the O p- and Cu d-orbitals. More importantly, the ubiquitous carbonate species firmly bound to the surface OVs block the formation of the secondary oxidative species via H₂O₂ activation, assuring the dominant role of the in situ generated O₂^•- for the selective HOC dehalogenation. The carbonate-deactivated OVs of the nCuO can be feasibly recovered via air annealing for sustainable dehalogenation. This work provides a new opportunity for selective O₂^•- generation via interfacial defect engineering for dehalogenation and other environmental applications.

The Quest to Quantify Selective and Synergistic Effects of Plasma for Cancer Treatment: Insights from Mathematical Modeling

Cold atmospheric plasma (CAP) and plasma-treated liquids (PTLs) have recently become a promising option for cancer treatment, but the underlying mechanisms of the anti-cancer effect are still to a large extent unknown. Although hydrogen peroxide (H2O2) has been recognized as the major anti-cancer agent of PTL and may enable selectivity in a certain concentration regime, the co-existence of nitrite can create a synergistic effect. We develop a mathematical model to describe the key species and features of the cellular response toward PTL. From the numerical solutions, we define a number of dependent variables, which represent feasible measures to quantify cell susceptibility in terms of the H2O2 membrane diffusion rate constant and the intracellular catalase concentration. For each of these dependent variables, we investigate the regimes of selective versus non-selective, and of synergistic versus non-synergistic effect to evaluate their potential role as a measure of cell susceptibility. Our results suggest that the maximal intracellular H2O2 concentration, which in the selective regime is almost four times greater for the most susceptible cells compared to the most resistant cells, could be used to quantify the cell susceptibility toward exogenous H2O2. We believe our theoretical approach brings novelty to the field of plasma oncology, and more broadly, to the field of redox biology, by proposing new ways to quantify the selective and synergistic anti-cancer effect of PTL in terms of inherent cell features.