Ruthenium complexes and treatment based on electronic excitation: a mechanistic approach focused on cytotoxic assessment by light irradiation, X-rays and ultrasound in 2D and 3D cancer cell lines

Abstract

Light irradiation has long been used in several countries as an approved therapy against cancer, in a technique called Photodynamic Therapy (PDT). Essentially, the process uses light, oxygen and a photosensitizer (PS) to produce reactive oxygen species (ROS). However, PDT has proven to be more effective for early stages of cancer, as many more advanced tumors are hypoxic. In this project, we present a new class of PSs based on ruthenium-phthalocyanine (Ru-Pc) and ruthenium-porphyrin complexes as agents for the production of ROS and reactive oxygen and nitrogen species (RONS) by electronic excitation. The cancer selectivity of these compounds can be achieved by targeting the complexes by inserting "L" axial ligands, generating [RuLL'(macrocycle)] species. All species described in the project produce ROS and para L as a ligand derived from nitrogen oxide, it is also capable of generating nitric oxide (NO), which has been evaluated as an anticancer agent depending on its concentration. In this context, synergistic effect between NO and reactive oxygen species (ROS) will be applied in the modulation of cell death in cancer cells. These studies aim to "advance" PDT and develop a new class of metal based-drugs. In this context, the project proposed here contributes to this development. The project focuses on the study of the biological effects of the presence of nitric oxide, as well as the effect of the presence of singlet oxygen on the regulation of signaling pathways in tumor cells with a special focus on the induction of death. In anticipation of in vivo application, results in two-dimensional and three-dimensional (3D) cell models will be used. Three-dimensional culture systems are an important tool for understanding molecular and cellular processes of compound/drug-induced cytotoxicity. 3D culture is being developed as one of the most advanced in vitro models for cellular organization capable of modulating the molecular gradients of living tissues such as oxygen, nutrients, metabolites and signaling molecules with the special advantage of reducing the need for animals for this analysis . The compounds used in this study absorb irradiation in the therapeutic window region and provide photoinduced electron transfer, which in the presence of ruthenium nitrosyl complexes release NO. The use of X-ray irradiation (X-PDT) and ultrasound (TSD), also described as one of the objectives of the project, has similar application to that by light irradiation. The biochemical mechanisms related to the ruthenium-cell complex interaction, as well as the identification, activation and regulation of cell death signaling pathways will be evaluated. For this purpose, the following analysis tools will be used: proteomics, Western blotting, confocal microscopy, flow cytometry and gene manipulation techniques, that is, silencing/exclusion of genes of interest. This study is expected to more briefly predict the role of ruthenium-nitrosyl complexes as a potential drug in the three-dimensional cancer cell lineage system. (AU)