Intertumoral heterogeneity in Glioblastoma dictates different cellular redox status and susceptibility to Photodynamic therapy with doped conjugated polymer nanoparticles

CAVERZÁN, MATÍAS DANIEL; BEAUGÉ, LUCÍA; CHESTA, CARLOS ALBERTO; PALACIOS, RODRIGO EMILIANO; IBARRA, LUIS EXEQUIEL

Mar del Plata

Congreso; REUNIÓN DE SOCIEDADES DE BIOCIENCIAS 2020; 2020

SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA

Glioblastoma (GBM) is the most aggressive malignant tumor of the CNS. It presents high recurrence and resistance to treatments. This leads to the search for new therapies that improve the prognosis of GBM. Conjugated polymer nanoparticles (CPNs) have been shown to be excellent photosensitizers (PS) in Photodynamic therapy (PDT). We have developed metallated porphyrin-doped CPNs for PDT. GBM presents inter and intratumoral cellular and genetic heterogeneity which include the adaptation to reactive oxygen species (ROS) and could be expressed as different basal levels of oxidative stress and antioxidant enzymes. The tumor heterogeneity and their associated difference in sensitivity to ROS-producing therapeutic agents must be taken into account in designing PDT protocols. Catalase (CAT), glutathione reductase (GSR) and superoxide dismutase 2 (SOD2) mRNA expressions in GBM samples were remarkably higher than that in normal tissues (GEPIA database). These expression patterns were used as biomarkers to predict the performance of CPN-PDT. CPN-PDT efficacy was compared in different GBM cell lines with different initial redox status. Basal mRNA expression levels of GSR, CAT and SOD2 were similar between U-87 MG and MO59K. However, T98G showed the highest levels for the 3 antioxidant enzymes. The inherent ROS level, quantified by DCFDA probe, was the lowest in T98G compared to the other two GBM cell lines. Cells were incubated with CPNs at various concentrations and subsequently irradiated with a MultiLED system. Cells not incubated with CPN were viable at all light doses, while a significant toxic effect was found in all cell lines after PDT. MO59K and U-87 MG cells died at a CPN concentration and light dose-dependent manner with very similar IC50 values. However, T98G cells were significantly more resistant to CNP-PDT. The superior resistance of T98G cells could be attributed to their higher antioxidant enzyme genes expression levels before and immediately after PDT.