Ferroptosis with Contributions from Apoptosis and Necroptosis in Porphyrazine III-Based Photodynamic Therapy of Primary Human Gliomas

Background: Photodynamic therapy (PDT) leading to immunogenic cell death (ICD) may serve as a promising basis for the development of antitumor therapeutic strategies. However, the mechanisms of action of photoinduced ICD in primary tumor cultures, including human glioma, remain unexplored. Methods: In the present study, the features of regulated cell death induced by photodynamic therapy using a previously described ICD inducer, porphyrazine III (pz III), were investigated. Cell death was studied in 7 primary cultures of high-grade human gliomas (astrocytomas, oligodendrogliomas, and glioblastomas). Results: Accumulation of porphyrazine III was observed in the endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and mitochondria; however, the distribution of the photosensitizer varied across different cultures. A narrow concentration window of porphyrazine III was established to effectively reach IC85, primarily inducing ferroptosis with contributions from apoptosis and necroptosis accompanied by superoxide anion generation and mitochondrial dysfunction. Conclusions: Given the immunogenic potential of ferroptosis, apoptosis and necroptosis we hypothesize that the induction of PDT using porphyrazine III in glioma will trigger immunogenic cell death.