talaporfin and Glioblastoma

The study aim to demonstrate the therapeutic tissue depth of photodynamic therapy (PDT) using the photosensitizer talaporfin sodium and semiconductor laser for malignant glioma from an autopsy finding. Three patients diagnosed with glioblastoma by pre-operative imaging (1 newly diagnosed patient and 2 patients with recurrence) were treated with intra-operative additional PDT and adjuvant therapy such as post-operative radiotherapy or chemotherapy. All three patients died of brain stem dysfunction owing to cerebrospinal fluid dissemination or direct invasion of the tumor cells from 13, 18, or 20 months after PDT. Antemortem magnetic resonance images demonstrated no tumor recurrence in the site of PDT, and autopsy was performed for the pathological analysis. Macroscopic observation demonstrated no tumor recurrence in two patients, but one patient demonstrated tumor recurrence in the therapeutic depth of PDT. Microscopic analysis demonstrated histopathological changes reaching depths of 9, 11, and 18 mm (mean: 12.7 mm) from the surface of the cavity of tumor resection, suggesting the therapeutic tissue depth of PDT to be in this range. This region demonstrated glial scarring with infiltration of T lymphocytes and macrophages, with slight degeneration of small vessel walls. However, viable tumor tissues were observed beyond or around the therapeutic tissue depth of PDT in two patients. PDT for glioblastoma prevented early local recurrence, which suggests the possibility that activation of the immune mechanisms was involved. The therapeutic tissue depth was suggested to be 9-18 mm from the surface of the cavity of tumor resection; however, the viable tumor tissues were demonstrated beyond this therapeutic range.

Topics: Adult; Autopsy; Female; Glioblastoma; Glioma; Humans; Male; Middle Aged; Neoplasm Recurrence, Local; Photochemotherapy; Photosensitizing Agents; Porphyrins; Retrospective Studies; Treatment Outcome

Photodynamic therapy (PDT) using photosensitizer induces several types of cell death, such as apoptosis, necrosis, and autophagy, depending on the PDT procedure, photosensitizer type, and cell type. We previously demonstrated that PDT using the photosensitizer talaporfin sodium (mono-L-aspartyl chlorine e6, NPe6; NPe6-PDT) induces both mitochondrial apoptotic and necrotic cell death in human glioblastoma T98G cells. However, details regarding the mechanism of necrosis caused by NPe6-PDT are unclear. Here, we investigated whether or not necroptosis, a recently suggested form of programmed necrosis, is involved in the necrotic cell death of NPe6-PDT-treated T98G cells. Leakage of lactate dehydrogenase (LDH) from the cell layer into conditioned medium was significantly increased by NPe6 (25 and 50 μg/ml)-PDT, indicating that NPe6-PDT induces necrosis in these cells. NPe6 (25 μg/ml)-PDT treatment also induced conversion of microtubule-associated protein 1 light-chain 3 (LC3)-I into phosphatidylethanolamine-conjugated LC3-II accompanying autophagosome formation, indicators of autophagy; however, of note, NPe6 (50 μg/ml)-PDT did not induce such autophagic changes. In addition, both necrostatin-1 (a necroptosis inhibitor) and knockdown of necroptotic pathway-related proteins [e.g., receptor interacting serine-threonine kinase (RIP)-1, RIP-3, and mixed lineage kinase domain-like protein (MLKL)] inhibited leakage of LDH caused by NPe6 (25 μg/ml)-PDT. Taken together, the present findings revealed that NPe6-PDT-induced necrotic cell death is mediated in part by the necroptosis pathway in glioblastoma T98G cells.

Topics: Apoptosis; Autophagy; Cell Line, Tumor; Chlorophyllides; Glioblastoma; Humans; L-Lactate Dehydrogenase; Microtubule-Associated Proteins; Necrosis; Phagosomes; Photochemotherapy; Photosensitizing Agents; Porphyrins

While photodynamic therapy (PDT) is an effective treatment for glioma, induction of apoptotic cell death of glioma cells is important for ensuring efficacy and safety of PDT treatment in glioma patients, as necrotic cell death can induce late appearance of obstacles in treatment. Here, we investigated the relationship between type of cell death and PDT treatment conditions involved in laser and photosensitizer dosage in human glioblastoma T98G cells. Photosensitizer talaporfin sodium-mediated PDT (NPe6-PDT) treatment induced laser and NPe6 dose-dependent cell death in T98G cells, whereas almost all cells pretreated with NPe6 at ≥ 30 µg/mL were killed by laser irradiation, regardless of laser dose. Morphological analysis showed that combination of high doses of NPe6 and laser irradiation changes the dominant cell death process from apoptosis to necrosis. Biochemical analysis (detection of caspase-3 activity and staining of cell surface-exposed phosphatidylserine) also showed that increasing laser dose changes the type of cell death from apoptotic to necrotic cell death after high-dose treatment with NPe6. Lactate dehydrogenase leakage assay demonstrated that a laser dose of 5 J/cm(2) induced less leakage than 30 J/cm(2). Our results suggested that type of glioma cell death in NPe6-PDT changed with fluctuations in laser and NPe6 dose, and that combination of 30 µg/mL NPe6 with 5 J/cm(2) laser is the best treatment condition for inducing an increase in apoptotic cells while keeping rate of necrotic cell death low in this in vitro study.

Topics: Antineoplastic Agents; Cell Death; Glioblastoma; Humans; Lasers; Photochemotherapy; Photosensitizing Agents; Porphyrins; Radiation Dosage; Tumor Cells, Cultured