phytochlorin and Glioblastoma

Glioblastoma (GBM) is a deadly brain tumor with poor prognosis and high mortality in patients. Given the low efficacy and serious side effects of current GBM therapy compared to those of conventional surgery, chemotherapy and radiation therapy, the development of a novel method for GBM management is very urgent. Sonodynamic therapy (SDT) has gained considerable attention in GBM therapy due to the advantages of deep tissue penetration and high biosafety. However, the low reactive oxygen species (ROS) generation efficacy of SDT has generally limited further applications and clinical translation. In this work, we report the simultaneous application of focused ultrasound-induced moderate thermal treatment (42 °C) and SDT for synergistic enhancement against GBM. Manganese ion (Mn2+)-chelated human serum albumin (HSA)-chlorin e6 (Ce6) nanoassemblies (HCM NAs) as targeting nanosonosensitizers were prepared using an assembly strategy. Our studies indicated that the HCM NAs had excellent T1-weighted contrast performance (12.2 mM-1 s-1) compared to that of clinically used Magnevist (4.3 mM-1 s-1) and achieved highly selective in vitro cell recognition and in vivo tumor-targeting magnetic resonance (MR) and fluorescence (FL) imaging with a signal-to-background ratio of 13.5 at 24 h post injection. Upon imaging-guided focused ultrasound irradiation, the temperature and reactive oxygen species (ROS) content of the tumor region increased simultaneously over time, achieving synergistic effects. The brain tumors were completely suppressed in subcutaneous mouse models of glioma, and the antitumor effect was greatly improved in orthotopic mouse models of glioma. It suggest that the synergistic treatment with moderate temperature and SDT induced by imaging-guided focused ultrasound is a promising platform against GMB, holds great potential in clinical settings.

Topics: Animals; Biological Transport; Cell Line, Tumor; Chlorophyllides; Combined Modality Therapy; Glioblastoma; Humans; Magnetic Resonance Imaging; Male; Mice; Nanostructures; Porphyrins; Serum Albumin, Human; Temperature; Ultrasonic Therapy

Photodynamic therapy (PDT) of malignant brain tumors is a promising adjunct to standard treatment, especially if tumor stem cells thought to be responsible for tumor progression and therapy resistance were also susceptible to this kind of treatment. However, some photosensitizers have been reported to be substrates of ABCG2, one of the membrane transporters mediating resistance to chemotherapy. Here we investigate, whether inhibition of ABCG2 can restore sensitivity to photosensitizer chlorin e6-mediated PDT.. Accumulation of chlorin e6 in wild type U87 and doxycycline-inducible U251 glioblastoma cells with or without induction of ABCG2 expression or ABCG2 inhibition by KO143 was analyzed using flow cytometry. In U251 cells, ABCG2 was inducible by doxycycline after stable transfection with a tet-on expression plasmid. Tumor sphere cultivation under low attachment conditions was used to enrich for cells with stem cell-like properties. PDT was done on monolayer cell cultures by irradiation with laser light at 665nm.. Elevated levels of ABCG2 in U87 cells grown as tumor spheres or in U251 cells after ABCG2 induction led to a 6-fold lower accumulation of chlorin e6 and the light dose needed to reduce cell viability by 50% (LD50) was 2.5 to 4-fold higher. Both accumulation and PDT response can be restored by KO143, an efficient non-toxic inhibitor of ABCG2.. Glioblastoma stem cells might escape phototoxic destruction by ABCG2-mediated reduction of photosensitizer accumulation. Inhibition of ABCG2 during photosensitizer accumulation and irradiation promises to restore full susceptibility of this crucial tumor cell population to photodynamic treatment.

Topics: ATP Binding Cassette Transporter, Subfamily G, Member 2; Cell Line, Tumor; Cell Survival; Chlorophyllides; Diketopiperazines; Doxycycline; Gene Expression; Glioblastoma; Heterocyclic Compounds, 4 or More Rings; Humans; Light; Niacinamide; Phenylurea Compounds; Photosensitizing Agents; Porphyrins; Sorafenib

Paclitaxel (PTX) can bind to human serum albumin (HSA) via hydrophobic interaction, forming Abraxane, which is a U.S. Food and Drug Administration (FDA) approved effective antitumor nanomedicine drug. Herein, the effective antitumor drug PTX is used to induce the self-assembly of HSA modified with either a photosensitizer chlorin e6 (Ce6), which at the same time serves as a chelating agent for Mn(2+) to enable magnetic resonance imaging, or acyclic Arg-Gly-Asp (cRGDyK) peptide that targets αvβ3-integrin overexpressed on tumor angiogenic endothelium. Two types of tumor-targeting theranostic nanoparticles are constructed, either by coassembly of both HSA-Ce6 and HSA-RGD simultaneously or by forming an HSA-Ce6@HSA-RGD core-shell structure, with the assistance of PTX-induced albumin aggregation. Such albumin-based nanoparticles on one hand could targetαvβ3-integrin, as evidenced by both in vitro and in vivo experiments, and on the other hand enable combined photodynamic/chemotherapy, which offers remarkably improved therapeutic efficacy to kill cancer in comparison to the respective monotherapies. Our work presents a new type of tumor-targeted multifunctional albumin-based nanoparticles by drug-induced self-assembly, which is a rather simple method without any sophisticated chemistry or materials engineering and is promising for multimodel imaging-guided combination therapy of cancer.

Topics: Animals; Cell Line, Tumor; Cell Transformation, Neoplastic; Chlorophyllides; Combined Modality Therapy; Female; Glioblastoma; Humans; Hydrophobic and Hydrophilic Interactions; Mice; Models, Molecular; Molecular Targeted Therapy; Oligopeptides; Paclitaxel; Porphyrins; Protein Aggregates; Protein Conformation; Serum Albumin; Theranostic Nanomedicine

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