Pre-treatment With Ranibizumab Aggravates PDT Injury and Alleviates Inflammatory Response in Choroid-Retinal Endothelial Cells

Necroptosis as a consequence of photodynamic therapy in tumor cells

Photodynamic therapy (PDT) is an alternative to cancer treatment, demonstrating selectivity and significant cytotoxicity on malignant tissues. Such therapy involves two nontoxic components: photosensitizer (PS) and non-ionizing radiation. In optimal dosage combinations, PDT causes cellular and tissue effects by oxygen-dependent processes, leading tumor cells to regulated cell death pathways. Regulated necrosis, called necroptosis, can be triggered by PDT and is characterized by caspase-8 inhibition and RIPK1, RIPK3, and MLKL activities, leading to plasma membrane pores formation with subsequent cellular content release into the extracellular space. For this review, studies accessed by PubMed describing the relation between necroptosis and PDT were summarized. The results showed that PDT can trigger necroptosis mechanisms in different tumor cells. Moreover, a mix of different cell death types can co-occur. It is also important to highlight that necroptosis triggered by PDT is related to damage-associated molecular patterns (DAMPs) release, involving immunogenic cell death and vaccination. The cell death response is directly related to the photosensitizer chemical characteristics, concentration, incubation time, cellular location, and irradiation parameters. The synergism among all cell death types is an excellent advantage for avowing tumor resistance mechanisms and developing new solutions.

Glycolysis-non-canonical glutamine dual-metabolism regulation nanodrug enhanced the phototherapy effect for pancreatic ductal adenocarcinoma treatment

Clinical pancreatic ductal adenocarcinoma (PDAC) treatment is severely limited by lack of effective KRAS suppression strategies. To address this dilemma, a reactive oxygen species (ROS)-responsive and PDAC-targeted nanodrug named Z/B-PLS was constructed to confront KRAS through dual-blockade of its downstream PI3K/AKT/mTOR and RAF/MEK/ERK for enhanced PDAC treatment. Specifically, photosensitizer zinc phthalocyanine (ZnPc) and PI3K/mTOR inhibitor BEZ235 (BEZ) were co-loaded into PLS which was constructed by click chemistry conjugating MEK inhibitor selumetinib (SEL) to low molecular weight heparin with ROS-responsive oxalate bond. The BEZ and SEL blocked PI3K/AKT/mTOR and RAF/MEK/ERK respectively to remodel glycolysis and non-canonical glutamine metabolism. ZnPc mediated photodynamic therapy (PDT) could enhance drug release through ROS generation, further facilitating KRAS downstream dual-blockade to create treatment-promoting drug delivery-therapeutic positive feedback. Benefiting from this broad metabolic modulation cascade, the metabolic symbiosis between normoxic and hypoxic tumor cells was also cut off simultaneously and effective tumor vascular normalization effects could be achieved. As a result, PDT was dramatically promoted through glycolysis-non-canonical glutamine dual-metabolism regulation, achieving complete elimination of tumors in vivo. Above all, this study achieved effective multidimensional metabolic modulation based on integrated smart nanodrug delivery, helping overcome the therapeutic challenges posed by KRAS mutations of PDAC.

Photodynamic therapy reduces cell viability, migration and triggers necroptosis in prostate tumor cells

Prostate cancer is the most common cancer in American men, aside from skin cancer. As an alternative cancer treatment, photodynamic laser therapy (PDT) can be used to induce cell death. We evaluated the PDT effect, using methylene blue as a photosensitizer, in human prostate tumor cells (PC3). PC3 were subjected to four different conditions: DMEM (control); laser treatment (L-660 nm, 100 mW, 100 J.cm^-2); methylene blue treatment (MB-25 μM, 30 min), and MB treatment followed by low-level red laser irradiation (MB-PDT). Groups were evaluated after 24 h. MB-PDT treatment reduced cell viability and migration. However, because MB-PDT did not significantly increase the levels of active caspase-3 and BCL-2, apoptosis was not the primary mode of cell death. MB-PDT, on the other hand, increased the acid compartment by 100% and the LC3 immunofluorescence (an autophagy marker) by 254%. Active MLKL level, a necroptosis marker, was higher in PC3 cells after MB-PDT treatment. Furthermore, MB-PDT resulted in oxidative stress due to a decrease in total antioxidant potential, catalase levels, and increased lipid peroxidation. According to these findings, MB-PDT therapy is effective at inducing oxidative stress and reducing PC3 cell viability. In such therapy, necroptosis is also an important mechanism of cell death triggered by autophagy.

Manipulate tumor hypoxia for improved photodynamic therapy using nanomaterials

Due to its low adverse effects, minimal invasiveness, and outstanding patient compliance, photodynamic therapy (PDT) has drawn a great deal of interest, which is achieved through incomplete reduction of O₂ by a photosensitizer under light illumination that produces amounts of reactive oxygen species (ROS). However, tumor hypoxia significantly hinders the therapeutic effect of PDT so that tumor cells cannot be eliminated, which results in tumor cells proliferating, invading, and metastasizing. Additionally, O₂ consumption during PDT exacerbates hypoxia in tumors, leading to several adverse events after PDT treatment. In recent years, various investigations have focused on conquering or using tumor hypoxia by nanomaterials to amplify PDT efficacy, which is summarized in this review. This comprehensive review's objective is to present novel viewpoints on the advancement of oxygenation nanomaterials in this promising field, which is motivated by hypoxia-associated anti-tumor therapy.

Overexpression of Rhodopsin or Its Mutants Leads to Energy Metabolism Dysfunction in 661w Cells

Purpose

Retinitis pigmentosa (RP) is a heterogeneous group of inherited disorders characterized by photoreceptor degeneration. The rhodopsin gene (RHO) is the most frequent cause of autosomal dominant RP (ADRP), yet it remains unclear how RHO mutations cause heterogeneous phenotypes. Energy failure is a main cause of the secondary cone death during RP progression; however, its role in primary rod death induced by ADRP RHO mutants is unknown.

Methods

Three RHO missense mutations were chosen from different clinical classes. Wild-type (WT) RHO and its mutants, P23H (class B1), R135L (class A), and G188R (class B2), were overexpressed in 661w cells, a mouse photoreceptor cell line, and their effects on oxidative phosphorylation (OXPHOS) and aerobic glycolysis were compared separately.

Results

Here, we report that energy failure is an early event in the cell death caused by overexpression of WT RHO and its mutants. RHO overexpression leads to OXPHOS deficiency, which might be a result of mitochondrial loss. Nonetheless, only in WT RHO and P23H groups, energy stress triggers AMP-activated protein kinase activation and metabolic reprogramming to increase glycolysis. Metabolic reprogramming impairment in R135L and G188R groups might be the reason why energy failure and cell injury are much more severe in those groups.

Conclusions

Our results imply that overexpression of RHO missense mutants have distinct impacts on the two energy metabolic pathways, which might be related to their heterogeneous phenotypes.

LS-HB-Mediated Photodynamic Therapy Inhibits Proliferation and Induces Cell Apoptosis in Melanoma

Chlorin e6-C-15-ethyl ester (LS-HB), a newly identified photosensitizer, was isolated from chlorin e6. The mechanism of tumor cell death induced by photodynamic therapy with LS-HB (LS-HB-PDT) is still unknown. Here, we investigated the photophysical properties of LS-HB, evaluated the antitumor effect on melanoma in vitro and in vivo, and explored its possible mechanisms. LS-HB not only has an optimal spectral band of red wavelength (660 nm) for photosensitization but also has favorable photostability. More importantly, LS-HB-PDT elicited a potent dose-dependent phototoxic effect in vitro. We discovered that LS-HB located in the mitochondria of B16F10 cells was able to generate excess reactive oxygen species, which subsequently resulted in mitochondrial membrane potential loss and induced apoptosis via caspase-9 and caspase-3 pathways. Moreover, PDT with LS-HB markedly inhibited the growth of melanoma in vivo. Therefore, LS-HB is expected to be an effective potential photosensitizer in antitumor therapy.