Metronomic photodynamic therapy in vitro evaluation for malignant gliomas

OLIVEDA P.M.; CAVERZAN M.D.; BEAUGE L.; PALACIOS R.E.; CHESTA C.A.; IBARRA L.E.

Mar del Plata

Congreso; Reunion Anual de Sociedades de Biociencias; 2022

SAIC

Glioblastoma (GBM) is the most aggressive brain tumor. New therapies are proposed such as Photodynamic Therapy (PDT) that combines light, oxygen and photosensitizers (PTs) to overcome conventional treatment issues. An important disadvantage of PDT using high light flux rates (PDTc) is the abrupt oxygen consumption, which leads to resistance to the treatment. PDT metronomic regimens (PDTm) administering light at low irradiation intensity could be an alternative to validate PDT for GBM. The main objective of the present work was to compare PDT effectiveness with conjugated polymer nanoparticles (CPN) in two modalities: PDTc or PDTm based on cell viability, impact in tumor microenvironment modulation and HIF-1α activation as indicator of oxygen consumption. To accomplish this, GBM cell lines U87MG y T98G and THP-1 macrophages were used. PDT efficacy was assayed in GBM mono-culture and co-culture with macrophages using 10 and 40 J/cm2 with 84 mW/cm2 and 17 mW/cm2 for PDTc and PDTm respectively. In order to determine the activation of HIF-1α, GBM MO59K cells genetically-modified to overexpress a GFP-associated with the hypoxia response element, where HIF binds, was used. GBM were incubated with CPN (3 and 6 ug/mL), then irradiated until reaching 10 J/cm2 in both modalities, and GFP expression was measured by flow cytometry. At 6 and 24 h after PDT, PDTc increased HIF-1α activation regarding PDTm. Cell viability was also dissimilar between PDTc and PDTm at the same CPN concentration and light doses (10 and 40 J/cm2). T98G cells were more resistant in both modalities and cell viability decreased significantly using PDTm (16,1;13,8;15,6; and 31,40 % with 47,5, 23,75, 11,875 y 5,93 ug/mL CPN) compared to PDTc (19,4, 35,8, 36,9% y 72,3% corresponding to CPN concentrations of 47,5, 23,75, 11,875 y 5,93 ug/mL) in U87MG. PDTm resulted in a more pronounce cell death with less HIF-1 activation as a main resistant molecular mechanism triggered proposing this modality as most suitable for GBM treatment.