Modeling of the sensitization effect using ruthenium complexes in 2D versus 3D cell cultures under normoxic and hypoxic conditions. Cytotoxic evaluation by light irradiation, X-rays and ¿-rays

• Grant number: 25/10422-7
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2025
• End date: September 30, 2028
• Field of knowledge: Health Sciences - Pharmacy
• Principal Investigator: Roberto Santana da Silva
• Grantee: Roberto Santana da Silva
• Host Institution: Faculdade de Ciências Farmacêuticas de Ribeirão Preto (FCFRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Global mortality data indicate that cancer is the second leading cause of death worldwide. Therefore, there is an urgent need for innovation in effective treatments to address this significant clinical and social challenge. Conventional photodynamic therapy (PDT) has proven effective in treating primary tumors and individual metastases, although it is ineffective against multiple disseminated metastases. The latter have thus become the main therapeutic target in oncology, and X-ray and/or ¿-ray-induced photodynamic therapy may offer an excellent alternative for the treatment of deep-seated tumors and dispersed metastases, provided the PDT principle is properly adapted to these forms of radiation. Essentially, the excitation of certain compounds by X-rays and/or ¿-rays results in luminescence, which can be captured by photosensitizers (PSs), consequently leading to the production of radical species. In this project, we propose to evaluate the anticancer effects of a synergistic approach using compounds that produce reactive oxygen and nitrogen species (RONS) when excited by light irradiation, X-rays, or ¿-rays. Photochemical, photophysical, and photobiological aspects will be examined in terms of ROS and NO generation. The cytotoxicity of the photosensitizers will be assessed both in the absence and presence of light and ionizing irradiation, against various cancer cell types and "normal" cells. The cytoprotective effect on normal cells, mediated by NO generated from the stimulation of ruthenium-nitrogen oxide complexes - previously observed in studies by our group (e.g., Negri et al., 2025) - will also be evaluated in this project. It is also noteworthy that different biological models will be employed to assess the cytotoxicity of inorganic compounds in cancer cells, which represents an innovative approach within the field of bioinorganic chemistry. Although many PSs are promising, challenges such as low selectivity, high toxicity, and reliance on in vitro models - which fail to accurately reproduce the complexity of primary tumors - have hindered their successful transition to clinical practice. To overcome these limitations, three-dimensional (3D) models are increasingly being used as preclinical platforms to enhance translational research and, consequently, clinical outcomes. In this context, bioprinted spheroids in hydrogels allow the creation of a more controlled microenvironment, improving spheroid arrangement and physiological relevance as we have recently described in our manuscript submitted to publication (da Silva, R.S. et al, Biofabrication, 2025). This system will be developed and explored in the present project. The biochemical mechanisms of cell death in different cancer cell lines, triggered by the three proposed excitation methods, will be investigated, allowing the analysis of protein expression and the elucidation of the underlying mechanisms of cell death. The synergistic effect of NO observed in the excitation processes will be studied by assessing cell recurrence using the Scratch Wound assay, as well as the regulation of survival mechanisms related to the expression of the anti-apoptotic transcription factor NF-¿B. (AU)