Ribosome-inactivating proteins and their immunotoxins for cancer therapy: insights into the mechanism of cell death

Ribosome-inactivating proteins (RIPs) are a family of plant toxic enzymes that permanently damage ribosomes and possibly other cellular substrates, thus causing cell death involving different and still not completely understood pathways. The high cytotoxic activity showed by many RIPs makes them ideal candidates for the production of immunotoxins (ITs), chimeric proteins designed for the selective elimination of unwanted or malignant cells. Saporin-S6, a type 1 RIP extracted from Saponaria officinalis L. seeds, has been extensively employed to construct anticancer conjugates because of its high enzymatic activity, stability and resistance to conjugation procedures, resulting in the efficient killing of target cells. Here we investigated the anticancer properties of two saporin-based ITs, anti-CD20 RTX/S6 and anti-CD22 OM124/S6, designed for the experimental treatment of B-cell NHLs. Both ITs showed high cytotoxicity towards CD20-positive B-cells, and their antitumor efficacy was enhanced synergistically by a combined treatment with proteasome inhibitors or fludarabine. Furthermore, the two ITs showed differencies in potency and ability to activate effector caspases, and a different behavior in the presence of the ROS scavenger catalase. Taken together, these results suggest that the different carriers employed to target saporin might influence saporin intracellular routing and saporin-induced cell death mechanisms. We also investigated the early cellular response to stenodactylin, a recently discovered highly toxic type 2 RIP representing an interesting candidate for the design and production of a new IT for the experimental treatment of cancer.

Modelling, diagnostics and experimental analysis of plasma assisted processes for material treatment

This work presents results from experimental investigations of several different atmospheric pressure plasmas applications, such as Metal Inert Gas (MIG) welding and Plasma Arc Cutting (PAC) and Welding (PAW) sources, as well as Inductively Coupled Plasma (ICP) torches. The main diagnostic tool that has been used is High Speed Imaging (HSI), often assisted by Schlieren imaging to analyse non-visible phenomena. Furthermore, starting from thermo-fluid-dynamic models developed by the University of Bologna group, such plasma processes have been studied also with new advanced models, focusing for instance on the interaction between a melting metal wire and a plasma, or considering non-equilibrium phenomena for diagnostics of plasma arcs. Additionally, the experimental diagnostic tools that have been developed for industrial thermal plasmas have been used also for the characterization of innovative low temperature atmospheric pressure non equilibrium plasmas, such as dielectric barrier discharges (DBD) and Plasma Jets. These sources are controlled by few kV voltage pulses with pulse rise time of few nanoseconds to avoid the formation of a plasma arc, with interesting applications in surface functionalization of thermosensitive materials. In order to investigate also bio-medical applications of thermal plasma, a self-developed quenching device has been connected to an ICP torch. Such device has allowed inactivation of several kinds of bacteria spread on petri dishes, by keeping the substrate temperature lower than 40 degrees, which is a strict requirement in order to allow the treatment of living tissues.