Photodynamic therapy with photofrin in combination with Buthionine Sulfoximine (BSO) of human glioma in the nude rat

An ultrasound-activated nanoplatform remodels tumor microenvironment through diverse cell death induction for improved immunotherapy

Although nanomaterial-based nanomedicine provides many powerful tools to treat cancer, most focus on the "immunosilent" apoptosis process. In contrast, ferroptosis and immunogenic cell death, two non-apoptotic forms of programmed cell death (PCD), have been shown to enhance or alter the activity of the immune system. Therefore, there is a need to design and develop nanoplatforms that can induce multiple modes of cell death other than apoptosis to stimulate antitumor immunity and remodel the immunosuppressive tumor microenvironment for cancer therapy. In this study, a new type of multifunctional nanocomposite mainly consisting of HMME, Fe3+ and Tannic acid, denoted HFT NPs, was designed and synthesized to induce multiple modes of cell death and prime the tumor microenvironment (TME). The HFT NPs consolidate two functions into one nano-system: HMME as a sonosensitizer for the generation of reactive oxygen species (ROS) 1O2 upon ultrasound irradiation, and Fe3+ as a GSH scavenger for the induction of ferroptosis and the production of ROS ·OH through inorganic catalytic reactions. The administration of HFT NPs and subsequent ultrasound treatment caused cell death through the consumption of GSH, the generation of ROS, ultimately inducing apoptosis, ferroptosis, and immunogenic cell death (ICD). More importantly, the combination of HFT NPs and ultrasound irradiation could reshape the TME and recruit more T cell infiltration, and its combination with immune checkpoint blockade anti-PD-1 antibody could eradicate tumors with low immunogenicity and a cold TME. This new nano-system integrates sonodynamic and chemodynamic properties to achieve outstanding therapeutic outcomes when combined with immunotherapy. Collectively, this study demonstrates that it is possible to potentiate cancer immunotherapy through the rational and innovative design of relatively simple materials.

Effects of redox modulation on quiescin/sulfhydryl oxidase activity of melanoma cells

Secreted quiescin/sulfhydryl oxidase (QSOX) is overexpressed in many tumor cell lines, including melanoma, and is usually associated with a pro-invasive phenotype. Our previous work described that B16-F10 cells enter in a quiescent state as a protective mechanism against damage generated by reactive oxygen species (ROS) during melanogenesis stimulation. Our present results show that QSOX activity was two-fold higher in cells with stimulated melanogenesis when compared to control cells. Considering that glutathione (GSH) is one of the main factor responsible for controlling redox homeostasis in cells, this work also aimed to investigate the relationship between QSOX activity, GSH levels and melanogenesis stimulation in B16-F10 murine melanoma cell line. The redox homeostasis was impaired by treating cells with GSH in excess or depleting its intracellular levels through BSO treatment. Interestingly, GSH-depleted cells without stimulation of melanogenesis kept high levels of viability, suggesting a possible adaptive mechanism of survival even under low GSH levels. They also showed lower extracellular activity of QSOX, and higher QSOX intracellular immunostaining, suggesting that this enzyme was less excreted from cells and corroborating with a diminished extracellular QSOX activity. On the other hand, cells under melanogenesis stimulation showed a lower GSH/GSSG ratio (8:1) in comparison with control (non-stimulated) cells (20:1), indicating a pro-oxidative state after stimulation. This was accompanied by decreased cell viability after GSH-depletion, no alterations in QSOX extracellular activity, but higher QSOX nucleic immunostaining. We suggest that melanogenesis stimulation and redox impairment caused by GSH-depletion enhanced the oxidative stress in these cells, contributing to additional alterations of its metabolic adaptive response.

Current Photodynamic Therapy for Glioma Treatment: An Update

Research on the development of photodynamic therapy for the treatment of brain tumors has shown promise in the treatment of this highly aggressive form of brain cancer. Analysis of both in vivo studies and clinical studies shows that photodynamic therapy can provide significant benefits, such as an improved median rate of survival. The use of photodynamic therapy is characterized by relatively few side effects, which is a significant advantage compared to conventional treatment methods such as often-used brain tumor surgery, advanced radiotherapy, and classic chemotherapy. Continued research in this area could bring significant advances, influencing future standards of treatment for this difficult and deadly disease.

Mn-Si-based nanoparticles-enhanced inhibitory effect on tumor growth and metastasis in photo-immunotherapy

The anticancer effect of phototherapy has been limited by some factors, including the easy degradation of photo agents, the complex tumor microenvironment, and the limited immune activation capacity, which impedes its efficiency in inhibiting tumor growth and tumor metastasis. Herein, Mn-doped mesoporous silica nanoparticles were synthesized to load the photo agent of IR 780, which were further coated with Mn (IMM). Notably, the combination of IMM and an 808 nm laser irradiation simultaneously inhibited the growth of primary tumors and distant untreated tumors in a bilateral animal model, which could be attributed to the protection of IMM to IR 780, the regulation functions to the tumor microenvironment, as well as the enhanced immune activation capacity. This work highlighted an alternative strategy for enhancing the inhibitory effect on both tumor growth and tumor metastasis in the combinational anticancer therapy of phototherapy and immunotherapy (photo-immunotherapy).

Photocatalytic Generation of Hydrogen Radical (H⋅) with GSH for Photodynamic Therapy

As a reactive hydrogen species, the hydrogen radical (H⋅) scarcely sees applications in tumor biological therapy due to the very limited bio-friendly sources of H⋅. In this work, we report that TAF can act as an organic photosensitizer as well as an efficient photocatalytic H⋅ generator with reduced glutathione (GSH) as a fuel. The photoactivation of TAF leads to cell death in two ways including triple amplification of oxidative stress via ferroptosis-apoptosis under normoxia and apoptosis through biological reductions under hypoxia. TAF presents excellent biosafety with ultrahigh photocytotoxicity index at an order of magnitude of 10² -10³ on both normoxic and hypoxic cells. The in vitro data suggest that H⋅ therapy is promising to overcome the challenge of tumor hypoxia at low doses of both photocatalyst and light. In addition, the capability of near-infrared two-photon excitation would benefit broad biological applications.

Photodynamic therapy: Innovative approaches for antibacterial and anticancer treatments

Photodynamic therapy is an alternative treatment mainly for cancer but also for bacterial infections. This treatment dates back to 1900 when a German medical school graduate Oscar Raab found a photodynamic effect while doing research for his doctoral dissertation with Professor Hermann von Tappeiner. Unexpectedly, Raab revealed that the toxicity of acridine on paramecium depends on the intensity of light in his laboratory. Photodynamic therapy is therefore based on the administration of a photosensitizer with subsequent light irradiation within the absorption maxima of this substance followed by reactive oxygen species formation and finally cell death. Although this treatment is not a novelty, there is an endeavor for various modifications to the therapy. For example, selectivity and efficiency of the photosensitizer, as well as irradiation with various types of light sources are still being modified to improve final results of the photodynamic therapy. The main aim of this review is to summarize anticancer and antibacterial modifications, namely various compounds, approaches, and techniques, to enhance the effectiveness of photodynamic therapy.

Accelerating skin regeneration and wound healing by controlled ROS from photodynamic treatment

Cellular metabolisms produce reactive oxygen species (ROS) which are essential for cellular signaling pathways and physiological functions. Nevertheless, ROS act as “double-edged swords” that have an unstable redox balance between ROS production and removal. A little raise of ROS results in cell proliferation enhancement, survival, and soft immune responses, while a high level of ROS could lead to cellular damage consequently protein, nucleic acid, and lipid damages and finally cell death. ROS play an important role in various pathological circumstances. On the contrary, ROS can show selective toxicity which is used against cancer cells and pathogens. Photodynamic therapy (PDT) is based on three important components including a photosensitizer (PS), oxygen, and light. Upon excitation of the PS at a specific wavelength, the PDT process begins which leads to ROS generation. ROS produced during PDT could induce two different pathways. If PDT produces control and low ROS, it can lead to cell proliferation and differentiation. However, excess production of ROS by PDT causes cellular photo damage which is the main mechanism used in cancer treatment. This review summarizes the functions of ROS in living systems and describes role of PDT in production of controllable ROS and finally a special focus on current ROS-generating therapeutic protocols for regeneration and wound healing.

Unraveling of Functional Activity of Primary Hippocampal Neuron-Glial Networks in Photodynamic Therapy Based on Tetracyanotetra(aryl)porphyrazines

The current efforts in photodynamic therapy (PDT) of brain cancer are focused on the development of novel photosensitizers with improved photodynamic properties, targeted specific localization, and sensitivity to the irradiation dose, ensuring the effectiveness of PDT with fewer side effects for normal nerve tissue. Here, we characterize the effects of four photosensitizers of the tetracyanotetra(aryl)porphyrazine group (pz I–IV) on the functional activity of neuron-glial networks in primary hippocampal cultures in their application in normal conditions and under PDT. The data revealed that the application of pz I–IV leads to a significant decrease in the main parameters of the functional calcium activity of neuron-glial networks and pronounced changes in the network characteristics. The observed negative effects of pz I–IV were aggravated under PDT. Considering the significant restructuring of the functional architectonics of neuron-glial networks that can lead to severe impairments in synaptic transmission and loss of brain functions, and the feasibility of direct application of PDT based on pz I–IV in the therapy of brain tumors is highly controversial. Nevertheless, the unique properties of pz I–IV retain a great prospect of their use in the therapy of tumors of another origin and cellular metabolism.

In vitro assessment of synergistic effects in combinations of a temoporfin-based photodynamic therapy with glutathione peroxidase 1 inhibitors

BACKGROUND

Due to an increased elimination of reactive oxygen species (ROS), in particular hydrogen peroxide (H₂O₂), overexpression of glutathione peroxidase 1 (GP_X1) can lead to an attenuation of apoptosis and development of resistance in cancer cells, thereby promoting tumor cell survival. Consequently, GP_X1 inhibitors have the potential to be used in cancer therapy as they support oxidative stress in cancer cells. Similarly, photodynamic therapy (PDT) induces oxidative stress in cancer cells by the formation of ROS upon illumination. Thus, both methods of treatment might act in synergy when used in combination.

METHODS

To investigate this hypothesis, combinations of the known GP_X1 inhibitors 9-chloro-6-ethyl-6H-[1,2,3,4,5]pentathiepino[6,7-b]indole (CEPI) or mercaptosuccinic acid (MSA) with PDT induced by the photosensitizer (PS) temoporfin (5,10,15,20-tetra(m-hydroxyphenyl)chlorin, mTHPC) were studied in vitro. This new combinatory approach was intended to accumulate ROS formed during PDT via blockage of GP_X1-catalyzed H₂O₂ degradation, and thus to enhance PDT-induced phototoxicity. Five human cancer cell lines from tumor origins treatable with PDT were utilized to investigate ROS generation, apoptosis induction, and cell cycle distribution.

RESULTS

Synergy was identified with both GP_X1 inhibitors, but not in all cell lines. ROS levels were increased after combined treatment with mTHPC and CEPI, but not MSA, in some cell lines, indicating that oxidative stress and ROS accumulation were enhanced by CEPI. Surprisingly, enhanced apoptosis induction was also observed with MSA afterwards, suggesting that other pathways contributed to the initiation of apoptosis. Cell cycle analysis confirmed apoptosis induction via the detection of DNA fragmentation.

CONCLUSION

A combination of GP_X1 inhibitors with mTHPC-PDT has the potential to generate synergistic effects and to increase overall phototoxicity, but the success of this combination approach was dependent on cancer type, and even antagonistic effects can occur.

One-Pot Synthesis of Multifunctional Carbon-Based Nanoparticle-Supported Dispersed Cu2+ Disrupts Redox Homeostasis to Enhance CDT

In chemodynamic therapy (CDT), the levels of reactive oxygen species (ROS) production plays an important role for evaluating the therapeutic efficacy. However, the high levels of glutathione (GSH) in tumor cells consume the ROS, directly reducing the therapeutic efficiency. Herein, we synthesized carbon-based nanoparticle (Cu-cys CBNPs) using one-pot strategy, which consume GSH via redox reactions to produce Cu⁺ that catalyze H₂ O₂ to produce ^. OH, thus the ROS level was observably increased through this synergistic effect. In vivo experiments further revealed that Cu-cys CBNPs could effectively inhibit tumor growth. Additionally, Cu-cys CBNPs can affect the activity of some protein sulfhydryl groups in cells, which was assessed by rdTOP-ABPP assay. In general, this study not only provides a potential CDT drug, but also provides a strategy for one-pot synthesis of multifunctional nanomaterials.

Janus -faced oxidant and antioxidant profiles of organo diselenides

To date, organoseleniums are pre-eminent for peroxide decomposition and radical quenching antioxidant activities. On the contrary, here, a series of Janus-faced aminophenolic diselenides have been prepared from substituted 2-iodoaniline and selenium powder using copper-catalyzed methodology. Subsequently, condensation with substituted salicylaldehyde afforded the Schiff base, which on reduction, yielded the desired substituted aminophenolic diselenides in 72%-88% yields. The generation of reactive oxygen species (ROS) from oxygen gas by the synthesized aminophenolic diselenides was studied by analyzing the oxidation of dichlorofluorescein diacetate (DCFDA) dye and para-nitro-thiophenol by fluorescence and UV-Visible spectroscopic methods. Furthermore, density functional theory calculations and crystal structure analysis revealed the role of functional amine and hydroxyl sites present in the Janus-faced organoselenium catalyst for the activation of molecular oxygen, where NH and phenolic groups bring the oxygen molecule close to the catalyst by N-H⋯O and O-H⋯O intermolecular interactions. Additionally, these functionalities stabilize the selenium-centered radical in the formed transition states. Antioxidant activities of the synthesized diselenides have been explored as the catalyst for the decomposition of hydrogen peroxide using benzenethiol sacrificial co-reductant by a well-established thiol assay. Radical quenching antioxidant activity was studied by the quenching of DPPH radicals at 516 nm by UV-Visible spectroscopy. The structure activity correlation suggests that the electron-rich phenol and electron-rich and sterically hindered selenium center enhance the oxidizing property of the aminophenolic diselenides. Janus-faced diselenides were also evaluated for their cytotoxic effect on HeLa cancer cells via MTT assay, which suggests that the compounds are effective at 15-18 μM concentration against cancer cells. Moreover, the combination with therapeutic anticancer drugs Erlotinib and Doxorubicin showed promising cytotoxicity at the nanomolar concentration (8-28 nM), which is sufficient to suppress the growth of the cancer cells.

Sulfasalazine Sensitizes Polyhematoporphyrin-Mediated Photodynamic Therapy in Cholangiocarcinoma by Targeting xCT

Cholangiocarcinoma (CCA), which is highly malignant, shows a relatively poor prognosis, due to the insensitivity of the tumour to chemotherapy and radiotherapy. Photodynamic therapy (PDT) has become a promising palliative therapeutic option for patients with unresectable cholangiocarcinoma (CCA), while the functional amount of ROS is limited by intracellular redox systemen. Sulfasalazine (SASP), a well-known anti-inflammatory agent, which also acts as an inhibitor of the amino acid transport system xc (xCT), decreases the intracellular glutathione (GSH) level, thus weakening the antioxidant defence of the cell by inhibition of the antiporter. However, the combination of SASP and PDT remains unexplored. We have reported that polyhematoporphyrin (PHP)-mediated PDT inhibits the cell viability of CCA cells and organoids. Furthermore, in PHP-enriched HCCC-9810 and TFK-1CCA cells, SASP enhances the sensitivity to PHP-mediated PDT through a GSH-dependent mechanism. We found that PHP-PDT can up-regulate xCT expression to promote cells against overloaded ROS, while SASP reduces GSH levels. After the combination of SASP and PHP-PDT, cell viability and GSH levels were significantly inhibited. xCT was also observed to be inhibited by SASP in human organoid samples. Our findings suggest that, in combination with PDT, SASP has potential as a promising approach against CCA.

Engineering nanomedicine for glutathione depletion-augmented cancer therapy

Glutathione (GSH), the main redox buffer, has long been recognized as a pivotal modulator of tumor initiation, progression and metastasis. It is also implicated in the resistance of platinum-based chemotherapy and radiation therapy. Therefore, depleting intracellular GSH was considered a potent solution to combating cancer. However, reducing GSH within cancer cells alone always failed to yield desirable therapeutic effects. In this regard, the convergence of GSH-scavenging agents with therapeutic drugs has thus been pursued in clinical practice. Unfortunately, the therapeutic outcomes are still unsatisfactory due to untargeted drug delivery. Advanced nanomedicine of synergistic GSH depletion and cancer treatment has attracted tremendous interest because they promise to deliver superior therapeutic benefits while alleviating life-threatening side effects. In the past five years, the authors and others have demonstrated that numerous nanomedicines, by simultaneously delivering GSH-depleting agents and therapeutic components, boost not only traditional chemotherapy and radiotherapy but also multifarious emerging treatment modalities, including photodynamic therapy, sonodynamic therapy, chemodynamic therapy, ferroptosis, and immunotherapy, to name a few, and achieved decent treatment outcomes in a large number of rodent tumor models. In this review, we summarize the most recent progress in engineering nanomedicine for GSH depletion-enhanced cancer therapies. Biosynthesis of GSH and various types of GSH-consuming strategies will be briefly introduced. The challenges and perspectives of leveraging nanomedicine for GSH consumption-augmented cancer therapies will be discussed at the end.

Gold nanoclusters as a GSH activated mitochondrial targeting photosensitizer for efficient treatment of malignant tumors

Gold nanoclusters (Au NCs), which have the characteristics of small size, near infrared (NIR) absorption and long triplet excited lifetime, have been used as a new type of photosensitizer for deep tissue photodynamic therapy (PDT). However, the therapeutic efficiency of the nano-system based on Au NCs still needs to be improved. Herein, we proposed a strategy using Mito-Au₂₅@MnO₂ nanocomposites to achieve enhanced PDT. Au₂₅(Capt)₁₈⁻ nanoclusters were applied as photosensitizers and further modified with peptides to target mitochondrial and MnO₂ nanosheets to consume glutathione (GSH). In the presence of GSH, Mito-Au₂₅@MnO₂ dis-integrated and Mito-Au₂₅ nanoparticles realized accurate mitochondrial targeting. Under the irradiation of 808 nm light, the nanocomposite ensured highly efficient PDT both in vitro and in vivo via oxidation pressure elevation and mitochondrial targeting in cancer cells.

This is the first example of mitochondrial targeting Au NCs capable of improving the efficiency of photodynamic therapy. Mito-Au₂₅@MnO₂ can be activated by consuming GSH and elevating oxidation pressure in cancer cells.

Glutathione-Depleting Nanomedicines for Synergistic Cancer Therapy

Cancer cells frequently exhibit resistance to various molecular and nanoscale drugs, which inevitably affects the drugs' therapeutic outcomes. Overexpression of glutathione (GSH) has been observed in many cancer cells, and solid evidence has corroborated the resulting tumor resistance to a variety of anticancer therapies, suggesting that this biochemical characteristic of cancer cells can be developed as a potential target for cancer treatments. The single treatment of GSH-depleting agents can potentiate the responses of the cancer cells to different cell death stimuli; therefore, as an adjunctive strategy, GSH depletion is usually combined with mainstream cancer therapies for enhancing the therapeutic outcomes. Propelled by the rapid development of nanotechnology, GSH-depleting agents can be readily constructed into anticancer nanomedicines, which have shown a steep rise over the past decade. Here, we review the common GSH-depleting nanomedicines which have been widely applied in synergistic cancer treatments in recent years. Some current challenges and future perspectives for GSH depletion-based cancer therapies are also presented. With the understanding of the structure-property relationship and action mechanisms of these biomaterials, we hope that the GSH-depleting nanotechnology will be further developed to realize more effective disease treatments and even achieve successful clinical translations.

Nano-assembly of ruthenium(II) photosensitizers for endogenous glutathione depletion and enhanced two-photon photodynamic therapy

Photodynamic therapy (PDT) is a promising noninvasive cancer treatment. PDT in the clinic faces several hurdles due to the unique tumor environment, a feature of which is high levels of glutathione (GSH). An excess amount of GSH consumes reactive oxygen species (ROS) generated by photosensitizers (PSs), reducing PDT efficiency. Herein, nano-photosensitizers (RuS1 NPs and RuS2 NPs) are reported. These consist of ruthenium complexes joined by disulfide bonds forming GSH sensitive polymer nanoparticles. The NPs achieve enhanced uptake compared to their constituent monomers. Inside cancer cells, high levels of GSH break the S-S bonds releasing PS molecules in the cell. The level of GSH is also then reduced leading to excellent PDT activity. Furthermore, RuS2 NPs functionalized with tumor targeting hyaluronic acid (HA@RuS2 NPs) assessed in vivo were highly effective with minimal side effects. To the best of our knowledge, RuS NPs are the first metal complex-based nano-assembled photosensitizers which exhibit enhanced specificity and consume endogenous GSH simultaneously, thus achieving excellent two-photon PDT efficiency in vitro and in vivo.

Terbium-Based AGuIX-Design Nanoparticle to Mediate X-ray-Induced Photodynamic Therapy

X-ray-induced photodynamic therapy is based on the energy transfer from a nanoscintillator to a photosensitizer molecule, whose activation leads to singlet oxygen and radical species generation, triggering cancer cells to cell death. Herein, we synthesized ultra-small nanoparticle chelated with Terbium (Tb) as a nanoscintillator and 5-(4-carboxyphenyl succinimide ester)-10,15,20-triphenyl porphyrin (P1) as a photosensitizer (AGuIX@Tb-P1). The synthesis was based on the AGuIX@ platform design. AGuIX@Tb-P1 was characterised for its photo-physical and physico-chemical properties. The effect of the nanoparticles was studied using human glioblastoma U-251 MG cells and was compared to treatment with AGuIX@ nanoparticles doped with Gadolinium (Gd) and P1 (AGuIX@Gd-P1). We demonstrated that the AGuIX@Tb-P1 design was consistent with X-ray photon energy transfer from Terbium to P1. Both nanoparticles had similar dark cytotoxicity and they were absorbed in a similar rate within the cells. Pre-treated cells exposure to X-rays was related to reactive species production. Using clonogenic assays, establishment of survival curves allowed discrimination of the impact of radiation treatment from X-ray-induced photodynamic effect. We showed that cell growth arrest was increased (35%-increase) when cells were treated with AGuIX@Tb-P1 compared to the nanoparticle doped with Gd.

Cell membranes targeted unimolecular prodrug for programmatic photodynamic-chemo therapy

Photodynamic therapy (PDT) has emerged as one of the most up-and-coming non-invasive therapeutic modalities for cancer therapy in rencent years. However, its therapeutic effect was still hampered by the short life span, limited diffusion distance and ineluctable depletion of singlet oxygen (1O2), as well as the hypoxic microenvironment in the tumor tissue. Such problems have limited the application of PDT and appropriate solutions are highly demand. Methods: Herein, a programmatic treatment strategy is proposed for the development of a smart molecular prodrug (D-bpy), which comprise a two-photon photosensitizer and a hypoxia-activated chemotherapeutic prodrug. A rhodamine dye was designed to connect them and track the drug release by the fluorescent signal generated through azo bond cleavage. Results: The prodrug (D-bpy) can stay on the cell membrane and enrich at the tumor site. Upon light irradiation, the therapeutic effect was enhanced by a stepwise treatment: (i) direct generation of 1O2 on the cell membrane induced membrane destruction and promoted the D-bpy uptake; (ii) deep tumor hypoxia caused by two-photon PDT process further triggered the activation of the chemotherapy prodrug. Both in vitro and in vivo experiments, D-bpy have exhabited excellent tumor treatment effect. Conclusion: The innovative programmatic treatment strategy provides new strategy for the design of follow-up anticancer drugs.

Enhancement of tumor lethality of ROS in photodynamic therapy

In the process of photodynamic therapy (PDT) treatment of tumors, reactive oxygen species (ROS) plays a key role in destroying tumor tissues. However, traditional PDT often has limited ROS killing capacity due to hypoxia in the tumor microenvironment (TME) or obstruction by the ROS defense system, resulting in poor efficacy. Therefore, enhancing the killing effect of ROS on tumors is the core of enhancing the anti-tumor effect of PDT. In recent years, many studies have developed a series of strategies to enhance the ability of ROS to kill tumors in view of the limitations of the TME on PDT. This article summarizes the commonly used or innovative strategies in recent years, including not only frequently used methods for hypoxia in the TME but also innovative strategies to inhibit the ROS defense system.

Understanding the glioblastoma tumor biology to optimize photodynamic therapy: From molecular to cellular events

Photodynamic therapy (PDT) has recently gained attention as an alternative treatment of malignant gliomas. Glioblastoma (GBM) is the most prevalent within tumors of the central nervous system (CNS). Conventional treatments for this CNS tumor include surgery, radiation, and chemotherapy. Surgery is still being considered as the treatment of choice. Even so, the poor prognosis and/or recurrence of the disease after applying any of these treatments highlight the urgency of exploring new therapies and/or improving existing ones to achieve the definitive eradication of tumor masses and remaining cells. PDT is a therapeutic modality that involves the destruction of tumor cells by reactive oxygen species induced by light, which were previously treated with a photosensitizing agent. However, in recent years, its experimental application has expanded to other effects that could improve overall performance against GBM. In the current review, we revisit the main advances of PDT for GBM management and also, the recent mechanistic insights about cellular and molecular aspects related to tumoral resistance to PDT of GBM.

Synthesis and characterization of ester-diol based polyurethane: a potentiality check for hypopharyngeal tissue engineering application

Abstract

Hypopharyngeal tissue engineering is increasing rapidly in this developing world. Tissue damage or loss needs the replacement by another biological or synthesized membrane using tissue engineering. Tissue engineering research is emerging to provide an effective solution for damaged tissue replacement. Polyurethane in tissue engineering has successfully been used to repair and restore the function of damaged tissues. In this context, Can polyurethane be a useful material to deal with hypopharyngeal tissue defects? To explore this, here ester diol based polyurethane (PU) was synthesized in two steps: firstly, polyethylene glycol 400 (PEG 400) was reacted with lactic acid to prepare ester diol, and then it was polymerized with hexamethylene diisocyanate. The physical, mechanical, and biological testing was done to testify the characterization of the membrane. The morphology of the synthesized membrane was investigated by using field emission scanning electron microscopy. Functional groups of the obtained membrane were characterized by fourier transform infrared spectroscopy spectroscopy. Several tests were performed to check the in vitro and in vivo biocompatibility of the membrane. A highly connected homogeneous network was obtained due to the appropriate orientation of a hard segment and soft segment in the synthesized membrane. Mechanical property analysis indicates the membrane has a strength of 5.15 MPa and strain 124%. The membrane showed high hemocompatibility, no cytotoxicity on peripheral blood mononuclear cell, and susceptible to degradation in simulated body fluid solution. Antimicrobial activity assessment has shown promising results against clinically significant bacteria. Primary hypopharyngeal cell growth on the PU membrane revealed the cytocompatibility and subcutaneous implantation on the back of Wistar rats were given in vivo biocompatibility of the membrane. Therefore, the synthesized material can be considered as a potential candidate for a hypopharyngeal tissue engineering application.

Graphic abstract

Surface-Charge-Switchable Nanoclusters for Magnetic Resonance Imaging-Guided and Glutathione Depletion-Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) is an effective noninvasive therapeutic method that employs photosensitizers (PSs) converting oxygen to highly cytotoxic singlet oxygen (¹O₂) under light irradiation. The conventional PDT efficacy is, however, compromised by the nonspecific delivery of PSs to tumor tissue, the hypoxic tumor microenvironment, and the reduction of generated ¹O₂ by the intracellular antioxidant glutathione (GSH). Herein, an intelligent multifunctional synergistic nanoplatform (CMGCC) for T₁-weighted magnetic resonance (MR) imaging-guided enhanced PDT is presented, which consists of nanoparticles composed of catalase (CAT) and manganese dioxide (MnO₂) that are integrated within chlorin-e6-modified glycol chitosan (GC) polymeric micelles. In this system, (1) GC polymers with pH-sensitive surface charge switchability from neutral to positive could improve the PS accumulation within the tumor region, (2) CAT could effectively reoxygenate the hypoxic tumor via catalyzing endogenous hydrogen peroxide to O₂, and (3) MnO₂ could consume the intracellular GSH while simultaneously producing Mn²⁺ as a contrast agent for T₁-weighted MR imaging. The CMGCC particles possess uniform size distribution, well-defined structure, favorable enzyme activity, and superior ¹O₂ generation ability. Both in vitro and in vivo experiments demonstrate that the CMGCC exhibit significantly enhanced PDT efficacy toward HeLa cells and subcutaneous HeLa tumors. Our study thereby demonstrates this to be a promising synergistic theranostic nanoplatform with highly efficient PDT performance for cancer therapy.

A phase Ι study to evaluate the application of photocyanine using pharmacokinetic and pharmacodynamic analysis in patients with malignancy

PURPOSE

Photodynamic therapy (PDT) schedules are based on sensitiser dose, light dose, and drug-light interval. The aim of the phase Ι study was to choose optimal dose and drug-light interval for PDT with photocyanine using pharmacokinetics (PK) and pharmacodynamics (PD).

METHODS

Twenty-eight cancer patients were enrolled. In trial A, 12 patients received one of four ascending doses of photocyanine intravenously 24 h prior to 180-270 J/cm² illumination. 0.2 mg/kg dose was infused to ten patients 12-48 h prior to 120 J/cm² illumination in trial B. In trial C, 0.1 mg/kg dose was infused to six patients 6 or 12 h prior to 180-270 J/cm² illumination. Serum concentrations of photocyanine were measured, and simulations were performed to assess the effect of drug exposure in tissue on responses.

RESULTS

Analysis of photocyanine levels of patients indicated that the two-compartment model best fit the data. Simulations showed that the rates of the drug entering tissues and leaving tissues were equal at 8-12 h after injection. Patients experienced pain which was related to photocyanine serum levels, especially with serum levels above 2500 ng/ml. Fewer non-responders were observed at serum levels higher than 1000 ng/ml for illumination at least 12 h after administration.

CONCLUSION

It is the first report of human trials of photocyanine, and the results suggested that patients receive 180 J/cm² illumination about 20-30 min at serum concentrations of photocyanine between 1000 and 2500 ng/ml at least 10 h after administration.

Biomedical application of manganese dioxide nanomaterials

Manganese dioxide nanomaterial is a new type of inorganic nanomaterial offering numerous advantages: simple preparation, low cost, and environmental friendliness. This review summarizes the traditional and novel synthetic methods for manganese dioxide nanomaterials and mainly discusses their potential in biomedical applications. Manganese dioxide nanomaterials are mainly used as drug carriers in tumor therapy. In recent years, the construction of multifunctional nano-platforms using manganese dioxide has gradually improved. The main mechanism is that manganese dioxide nanomaterials can combine with reactive oxygen species in the tumor microenvironment to alleviate tumor hypoxia. Manganese dioxide has also been used to quench fluorescent carbon dots in fluorescent probes. Based on the oxidation ability and catalytic activity of MnO₂, MnO₂ nanosheets are widely used to build biosensors. New research shows that manganese dioxide nanomaterials also have great potential in gene therapy and nuclear magnetic imaging.

Advances in nanomaterials for photodynamic therapy applications: Status and challenges

Photodynamic therapy (PDT), as a non-invasive therapeutic modality that is alternative to radiotherapy and chemotherapy, is extensively investigated for cancer treatments. Although conventional organic photosensitizers (PSs) are still widely used and have achieved great progresses in PDT, the disadvantages such as hydrophobicity, poor stability within PDT environment and low cell/tissue specificity largely limit their clinical applications. Consequently, nano-agents with promising physicochemical and optical properties have emerged as an attractive alternative to overcome these drawbacks of traditional PSs. Herein, the up-to-date advances in the fabrication and fascinating applications of various nanomaterials in PDT have been summarized, including various types of nanoparticles, carbon-based nanomaterials, and two-dimensional nanomaterials, etc. In addition, the current challenges for the clinical use of PDT, and the corresponding strategies to address these issues, as well as future perspectives on further improvement of PDT have also been discussed.

Cell death in photodynamic therapy: From oxidative stress to anti-tumor immunity

Photodynamic therapy is a promising approach for cancer treatment that relies on the administration of a photosensitizer followed by tumor illumination. The generated oxidative stress may activate multiple mechanisms of cell death which are counteracted by cells through adaptive stress responses that target homeostasis rescue. The present renaissance of PDT was leveraged by the acknowledgment that this therapy has an immediate impact locally, in the illumination volume, but that subsequently it may also elicit immune responses with systemic impact. The investigation of the mechanisms of cell death under the oxidative stress of PDT is of paramount importance to understand how the immune system is activated and, ultimately, to make PDT a more appealing/relevant therapeutic option.

Potentiating photodynamic therapy of ICG-loaded nanoparticles by depleting GSH with PEITC

Photodynamic therapy (PDT) is a clinically approved cancer treatment which utilizes reactive oxygen species (ROS) to eradicate cancer cells. But the high concentration of GSH inside tumor cells can neutralize the generated ROS during PDT, resulting in an insufficient therapeutic effect. To address this issue, we combined ICG-loaded nanoparticles with PEITC for potent PDT. ICG encapsulated in novel hydroxyethyl starch-oleic acid conjugate (HES-OA) nanoparticles (∼50 nm) exhibited excellent stability and efficient singlet oxygen generation under laser irradiation, promoted cellular uptake, and enhanced tumor accumulation, whilst PEITC depleted intracellular GSH significantly. As a result, PDT based on ICG-loaded NPs combined with PEITC synergistically suppressed cancer cells both in vitro and in vivo. Potentiating ICG-loaded NPs with PEITC represents a novel and efficient strategy to enhance PDT efficacy.

Graphene-Based Smart Platforms for Combined Cancer Therapy

The extensive research of graphene and its derivatives in biomedical applications during the past few years has witnessed its significance in the field of nanomedicine. Starting from simple drug delivery systems, the application of graphene and its derivatives has been extended to a versatile platform of multiple therapeutic modalities, including photothermal therapy, photodynamic therapy, magnetic hyperthermia therapy, and sonodynamic therapy. In addition to monotherapy, graphene-based materials are widely applied in combined therapies for enhanced anticancer activity and reduced side effects. In particular, graphene-based materials are often designed and fabricated as "smart" platforms for stimuli-responsive nanocarriers, whose therapeutic effects can be activated by the tumor microenvironment, such as acidic pH and elevated glutathione (termed as "endogenous stimuli"), or light, magnetic, or ultrasonic stimuli (termed as "exogenous stimuli"). Herein, the recent advances of smart graphene platforms for combined therapy applications are presented, starting with the principle for the design of graphene-based smart platforms in combined therapy applications. Next, recent advances of combined therapies contributed by graphene-based materials, including chemotherapy-based, photothermal-therapy-based, and ultrasound-therapy-based synergistic therapy, are outlined. In addition, current challenges and future prospects regarding this promising field are discussed.

The intracellular redox environment modulates the cytotoxic efficacy of single and combination chemotherapy in breast cancer cells using photochemical internalisation

The redox environment modulates photochemical internalization of an entrapped cytotoxic agent. Administration of light depicted by jagged arrow.

Self-Assembled Minimalist Multifunctional Theranostic Nanoplatform for Magnetic Resonance Imaging-Guided Tumor Photodynamic Therapy

Minimalist multifunctional platforms for delivering diagnostic and therapeutic agents effectively and safely into tumor sites are highly desired in nanomedicine. Herein, we describe the fabrication of a supramolecular nanoplatform via the amphiphilic amino acid (9-fluorenylmethyloxycarbonyl-l-leucine, Fmoc-l-L)-modulated self-assembly of a magnetic resonance imaging (MRI) contrast agent (ionic manganese, Mn²⁺) and photosensitive drug (chlorin e6, Ce6). Coordination drives the coassembly of Fmoc-l-L and Mn²⁺ to generate a nanoscale supramolecular network to adaptively encapsulate Ce6. The obtained biometal-organic nanoparticles exhibit a high drug loading capability, inherent good biocompatibility, robust stability, and smart disassembly in response to glutathione (GSH). The cooperative assembly of the multiple components is synchronously dynamic in nature and enables enhanced photodynamic therapy (PDT) to damage tumor cells and tissue by efficiently delivering the photosensitizer and improving the reductive tumor microenvironment via the competitive coordination of GSH with Mn²⁺. The antitumor effect can also be monitored and evaluated in vivo by MRI through the long-term intracellular biochelation of Mn²⁺. Therefore, this work presents a one-pot and robust method for the self-assembly of a multifunctional theranostic nanoplatform capable of MRI-guided PDT starting from minimalist biological building blocks.

Mechanistic Insight into the Light-Irradiated Carbon Capsules as an Antibacterial Agent

Infections caused by bacteria are a growing global challenge for public health as bacteria develop resistance, which will cause the failure of anti-infective treatment eventually. An effective alternative strategy to traditional antibacterial therapy is utilizing reactive oxygen species (ROS) to kill bacteria. Here, we report a simple route to prepare PEGylated nitrogen-doped carbon capsules (PEG-N-CCs) as an antibacterial agent. The PEG-N-CCs can translate near-infrared light (NIR) into heat and produce a high concentration of ROS triggered by NIR irradiation. Both heating and ROS are critical to destroy the outer membranes and rupture cell bodies, causing DNA fragmentation and glutathione oxidation both in Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and their multidrug-resistant strains. Moreover, PEG-N-CCs plus NIR irradiation can efficiently scavenge the existing biofilms and prevent the formation of new biofilms, killing planktonic bacteria as well as those within the biofilm. Our studies prove that the PEG-N-CCs plus NIR irradiation can provide a simple and effective platform for combating bacteria, employing carbon nanomaterials as an antibacterial alternative for treatment of infectious diseases.

5-FU resistant EMT-like pancreatic cancer cells are hypersensitive to photochemical internalization of the novel endoglin-targeting immunotoxin CD105-saporin

BACKGROUND

Development of resistance to 5-fluorouracil (5-FU) is a major problem in treatment of various cancers including pancreatic cancer. In this study, we reveal important resistance mechanisms and photochemical strategies to overcome 5-FU resistance in pancreatic adenocarcinoma.

METHODS

5-FU resistant (5-FUR), epithelial-to-mesenchymal-like sub-clones of the wild type pancreatic cancer cell line Panc03.27 were previously generated in our lab. We investigated the cytotoxic effect of the endosomal/lysosomal-localizing photosensitizer TPCS2a (fimaporfin) combined with light (photochemical treatment, PCT) using MTS viability assay, and used fluorescence microscopy to show localization of TPCS2a and to investigate the effect of photodamage of lysosomes. Flow cytometric analysis was performed to investigate uptake of photosensitizer and to assess intracellular ROS levels. Expression and localization of LAMP1 was assessed using RT-qPCR, western blotting, and structured illumination microscopy. MTS viability assay was used to assess the effect of combinations of 5-FU, chloroquine (CQ), and photochemical treatment. Expression of CD105 was investigated using RT-qPCR, western blotting, flow cytometry, and fluorescence microscopy, and co-localization of TPCS2a and anti-CD105-saporin was assessed using microscopy. Lastly, the MTS assay was used to investigate cytotoxic effects of photochemical internalization (PCI) of the anti-CD105-immunotoxin.

RESULTS

The 5-FUR cell lines display hypersensitivity to PCT, which was linked to increased uptake of TPCS2a, altered lysosomal distribution, lysosomal photodamage and increased expression of the lysosomal marker LAMP-1 in the 5-FUR cells. We show that inhibition of autophagy induced by either chloroquine or lysosomal photodamage increases the sensitivity to 5-FU in the resistant cells. The three 5-FUR sub-clones overexpress Endoglin (CD105). Treatment with the immunotoxin anti-CD105-saporin alone significantly reduced the viability of the CD105-expressing 5-FUR cells, whereas little effect was seen in the CD105-negative non-resistant parental cancer cell lines. Strikingly, using the intracellular drug delivery method photochemical internalization (PCI) by combining light-controlled activation of the TPCS2a with nanomolar levels of CD105-saporin resulted in strong cytotoxic effects in the 5-FUR cell population.

CONCLUSION

Our findings suggested that autophagy is an important resistance mechanism against the chemotherapeutic drug 5-FU in pancreatic cancer cells, and that inhibition of the autophagy process, either by CQ or lysosomal photodamage, can contribute to increased sensitivity to 5-FU. For the first time, we demonstrate the promise of PCI-based targeting of CD105 in site-specific elimination of 5-FU resistant pancreatic cancer cells in vitro. In conclusion, PCI-based targeting of CD105 may represent a potent anticancer strategy and should be further evaluated in pre-clinical models.

The diverse roles of glutathione-associated cell resistance against hypericin photodynamic therapy

The diverse responses of different cancers to treatments such as photodynamic therapy of cancer (PDT) have fueled a growing need for reliable predictive markers for treatment outcome. In the present work we have studied the differential response of two phenotypically and genotypically different breast adenocarcinoma cell lines, MCF7 and MDA-MB-231, to hypericin PDT (HYP-PDT). MDA-MB-231 cells were 70% more sensitive to HYP PDT than MCF7 cells at LD50. MCF7 were found to express a substantially higher level of glutathione peroxidase (GPX4) than MDA-MB-231, while MDA-MB-231 differentially expressed glutathione-S-transferase (GSTP1), mainly used for xenobiotic detoxification. Eighty % reduction of intracellular glutathione (GSH) by buthionine sulfoximine (BSO), largely enhanced the sensitivity of the GSTP1 expressing MDA-MB-231 cells to HYP-PDT, but not in MCF7 cells. Further inhibition of the GSH reduction however by carmustine (BCNU) resulted in an enhanced sensitivity of MCF7 to HYP-PDT. HYP loading studies suggested that HYP can be a substrate of GSTP for GSH conjugation as BSO enhanced the cellular HYP accumulation by 20% in MDA-MB-231 cells, but not in MCF7 cells. Studies in solutions showed that L-cysteine can bind the GSTP substrate CDNB in the absence of GSTP. This means that the GSTP-lacking MCF7 may use L-cysteine for xenobiotic detoxification, especially during GSH synthesis inhibition, which leads to L-cysteine build-up. This was confirmed by the lowered accumulation of HYP in both cell lines in the presence of BSO and the L-cysteine source NAC. NAC reduced the sensitivity of MCF7, but not MDA-MB-231, cells to HYP PDT which is in accordance with the antioxidant effects of L-cysteine and its potential as a GSTP substrate. As a conclusion we have herein shown that the different GSH based cell defense mechanisms can be utilized as predictive markers for the outcome of PDT and as a guide for selecting optimal combination strategies.

A Smart Photosensitizer-Manganese Dioxide Nanosystem for Enhanced Photodynamic Therapy by Reducing Glutathione Levels in Cancer Cells

Photodynamic therapy (PDT) has been applied in cancer treatment by utilizing reactive oxygen species to kill cancer cells. However, a high concentration of glutathione (GSH) is present in cancer cells and can consume reactive oxygen species. To address this problem, we report the development of a photosensitizer-MnO2 nanosystem for highly efficient PDT. In our design, MnO2 nanosheets adsorb photosensitizer chlorin e6 (Ce6), protect it from self-destruction upon light irradiation, and efficiently deliver it into cells. The nanosystem also inhibits extracellular singlet oxygen generation by Ce6, leading to fewer side effects. Once endocytosed, the MnO2 nanosheets are reduced by intracellular GSH. As a result, the nanosystem is disintegrated, simultaneously releasing Ce6 and decreasing the level of GSH for highly efficient PDT. Moreover, fluorescence recovery, accompanied by the dissolution of MnO2 nanosheets, can provide a fluorescence signal for monitoring the efficacy of delivery.

Vitamin D in cancer chemoprevention

CONTEXT

There is increasing evidence that Vitamin D (Vit D) and its metabolites, besides their well-known calcium-related functions, may also exert antiproliferative, pro-differentiating, and immune modulatory effects on tumor cells in vitro and may also delay tumor growth in vivo.

OBJECTIVE

The aim of this review is to provide fresh insight into the most recent advances on the role of Vit D and its analogues as chemopreventive drugs in cancer therapy.

METHODS

A systematic review of experimental and clinical studies on Vit D and cancer was undertaken by using the major electronic health database including ISI Web of Science, Medline, PubMed, Scopus and Google Scholar.

RESULTS AND CONCLUSION

Experimental and clinical observations suggest that Vit D and its analogues may be effective in preventing the malignant transformation and/or the progression of various types of human tumors including breast cancer, prostate cancer, colorectal cancer, and some hematological malignances. These findings suggest the possibility of the clinical use of these molecules as novel potential chemopreventive and anticancer agents.

MicroRNAs associated with the efficacy of photodynamic therapy in biliary tract cancer cell lines

Photodynamic therapy (PDT) is a palliative treatment option for unresectable hilar biliary tract cancer (BTC) showing a considerable benefit for survival and quality of life with few side effects. Currently, factors determining the cellular response of BTC cells towards PDT are unknown. Due to their multifaceted nature, microRNAs (miRs) are a promising analyte to investigate the cellular mechanisms following PDT. For two photosensitizers, Photofrin® and Foscan®, the phototoxicity was investigated in eight BTC cell lines. Each cell line (untreated) was profiled for expression of n=754 miRs using TaqMan® Array Human MicroRNA Cards. Statistical analysis and bioinformatic tools were used to identify miRs associated with PDT efficiency and their putative targets, respectively. Twenty miRs correlated significantly with either high or low PDT efficiency. PDT was particularly effective in cells with high levels of clustered miRs 25-93*-106b and (in case of miR-106b) a phenotype characterized by high expression of the mesenchymal marker vimentin and high proliferation (cyclinD1 and Ki67 expression). Insensitivity towards PDT was associated with high miR-200 family expression and (for miR-cluster 200a/b-429) expression of differentiation markers Ck19 and Ck8/18. Predicted and validated downstream targets indicate plausible involvement of miRs 20a*, 25, 93*, 130a, 141, 200a, 200c and 203 in response mechanisms to PDT, suggesting that targeting these miRs could improve susceptibility to PDT in insensitive cell lines. Taken together, the miRNome pattern may provide a novel tool for predicting the efficiency of PDT and-following appropriate functional verification-may subsequently allow for optimization of the PDT protocol.

Role of glutamate transporters in redox homeostasis of the brain

Redox homeostasis is especially important in the brain where high oxygen consumption produces an abundance of harmful oxidative by-products. Glutathione (GSH) is a tripeptide non-protein thiol. It is the central nervous system's most abundant antioxidant and the master controller of brain redox homeostasis. The glutamate transporters, System xc(-) (SXC) and the Excitatory Amino Acid Transporters (EAAT), play important, synergistic roles in the synthesis of GSH. In glial cells, SXC mediates the uptake of cystine, which after intracellular reduction to cysteine, reacts with glutamate during the rate-limiting step of GSH synthesis. EAAT3 mediates direct cysteine uptake for neuronal GSH synthesis. SXC and EAAT work in concert in glial cells to provide two intracellular substrates for GSH synthesis, cystine and glutamate. Their cyclical basal function also prevents a buildup of extracellular glutamate, which SXC releases extracellularly in exchange for cystine uptake. Maintaining extracellular glutamate homeostasis is critical to prevent neuronal toxicity, as well as glutamate-mediated SXC inhibition, which could lead to a depletion of intracellular GSH and loss of cellular redox control. Many neurological diseases show evidence of GSH dysfunction, and increased GSH has been widely associated with chemotherapy and radiotherapy resistance of gliomas. We present evidence suggesting that gliomas expressing elevated levels of SXC are more reliant on GSH for growth and survival. They have an increased inherent radiation resistance, however, inhibition of SXC can increase tumor sensitivity at low radiation doses. GSH depletion through SXC inhibition may be a viable mechanism to enhance current glioma treatment strategies and make tumors more sensitive to radiation and chemotherapy protocols.