An update in clinical utilization of photodynamic therapy for lung cancer

Novel tris-bipyridine based Ru(II) complexes as type-I/-II photosensitizers for antitumor photodynamic therapy through ferroptosis and immunogenic cell death

Ru(II) complexes have attracted attention as photosensitizers for their promising photodynamic properties. Herein, novel tris-bipyridine based Ru(II) complexes (6a-e) were synthesized by introducing saturated heterocycles to improve photodynamic properties and lipid-water partition coefficients. Among them, 6d demonstrated significant phototoxicity towards three cancer cells, with IC50 values of 5.66-7.17 μM, exceeding values in dark (IC50s > 100 μM). Under hypoxic conditions, 6d maintained excellent photodynamic activity in A549 cells, with PI values exceeding 24, highlighting its potential for highly effective type-I/-II photodynamic therapy by inducing ROS generation, oxidative stress, and mitochondrial damage. Additionally, it induced ferroptosis and immunogenic cell death of A549 cells by regulating the expression of relevant markers. Finally, 6d remarkably inhibited the growth of A549 transplanted tumor growth by 95.4 %. This Ru(II) complex shows great potential for cancer treatment with its potent photodynamic activity and diverse mechanisms of tumor cell death.

Photoactivated Anticancer Activity of Cobalt(III) Complexes with Naturally Occurring Flavonoids Chrysin and Silibinin

Photoactive metal complexes of bioessential transition metal ions with natural chelators are gaining interest as photocytotoxic agents for cancer photodynamic therapy (PDT). We report six new cobalt(III) complexes with a mixed-ligand formulation [Co(B)2(L)](ClO4)2 (Co1-Co6), where B represents a N,N-donor α-diimine ligand, namely, phenanthroline (phen; Co1, Co2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq; Co3, Co4), and dipyrido[3,2-a:2',3'-c]phenazine (dppz; Co5, Co6), and L is the monoanionic form of the naturally occurring flavonoids chrysin (chry; Co1, Co3, Co5) and silibinin (sili; Co2, Co4, Co6). Complexes displayed a d-d absorption band within 500-700 nm and exhibited excellent dark and photostability in solution. Cytotoxicity studies indicated significant activity of Co5 and Co6 against cervical (HeLa) and lung (A549) cancer cells under visible light (400-700 nm) irradiation giving low micromolar IC50 values (2.3-3.4 μM, phototoxicity index~15-30). The complexes demonstrated notably low toxicity against normal HPL1D lung epithelial cells. Flow cytometry assay revealed an apoptotic mode of cell damage triggered by the complexes when irradiated. ROS generation assay indicated the involvement of singlet oxygen species in the cell death mechanism when irradiated with light. Overall, complexes Co5 and Co6 with coordinated dipyridophenazine and flavonoid ligands are potential candidates for cancer PDT applications.

Micelles of poly[oligo(ethylene glycol) methacrylate] as delivery vehicles for zinc phthalocyanine photosensitizers

Drug-loaded polymeric micelles have proven to be highly effective carrier systems for the efficient delivery of hydrophobic photosensitizers (PSs) in photodynamic therapy (PDT). This study introduces the micellization potential of poly(oligoethylene glycol methyl ether methacrylate) (pOEGMA) as a novel approach, utilizing the hydrophobic methacrylate segments of pOEGMA to interact with highly hydrophobic zinc phthalocyanine (ZnPc), thereby forming a potential micellar drug carrier system. The ZnPc molecule was synthesized from phthalonitrile derivatives and its fluorescence, photodegradation, and singlet oxygen quantum yields were determined in various solvents. In solvents such as tetrahydrofuran, dimethyl sulfoxide, and N,N-dimethylformamide, the ZnPc compound exhibited the requisite photophysical and photochemical properties for PDT applications. The pOEGMA homopolymer was synthesized via reversible addition-fragmentation chain-transfer polymerization, while ZnPc-loaded pOEGMA micelles were prepared using the nanoprecipitation method. Characterization of the pOEGMA, ZnPc, and micelles was conducted using FTIR,1H-NMR, dynamic light scattering, matrix-assisted laser desorption/ionization time-of-flight mass spectrometries, gel permeation chromatography, and transmission electron microscopy. The critical micelle concentration was determined to be 0.027 mg ml-1using fluorescence spectrometry. The drug loading and encapsulation efficiencies of the ZnPc-loaded micelles were calculated to be 0.67% and 0.47%, respectively. Additionally, the release performance of ZnPc from pOEGMA micelles was monitored over a period of nearly 10 d, while the lyophilized micelles exhibited stability for 3 months. Lastly, the ZnPc-loaded micelles were more biocompatible than ZnPc on L929 cell line. The results suggest that the pOEGMA homopolymer possesses the capability to micellize through its methacrylate segments when interacting with highly hydrophobic molecules, presenting a promising avenue for enhancing the delivery efficiency of hydrophobic PSs in PDT. Moreover, it was also deciphered that obtained formulations were highly biocompatible according to cytotoxicity results and could be safely employed as drug delivery systems in further applications.

Advances in Medicine: Photodynamic Therapy

Over the past decades, medicine has made enormous progress, revolutionized by modern technologies and innovative therapeutic approaches. One of the most exciting branches of these developments is photodynamic therapy (PDT). Using a combination of light of a specific wavelength and specially designed photosensitizing substances, PDT offers new perspectives in the fight against cancer, bacterial infections, and other diseases that are resistant to traditional treatment methods. In today's world, where there is a growing problem of drug resistance, the search for alternative therapies is becoming more and more urgent. Imagine that we could destroy cancer cells or bacteria using light, without the need to use strong chemicals or antibiotics. This is what PDT promises. By activating photosensitizers using appropriately adjusted light, this therapy can induce the death of cancer or bacterial cells while minimizing damage to surrounding healthy tissues. In this work, we will explore this fascinating method, discovering its mechanisms of action, clinical applications, and development prospects. We will also analyze the latest research and patient testimonies to understand the potential of PDT for the future of medicine.

Uncovering Porphyrin Accumulation in the Tumor Microenvironment

Heme, an iron-containing tetrapyrrole, is essential in almost all organisms. Heme biosynthesis needs to be precisely regulated particularly given the potential cytotoxicity of protoporphyrin IX, the intermediate preceding heme formation. Here, we report on the porphyrin intermediate accumulation within the tumor microenvironment (TME), which we propose to result from dysregulation of heme biosynthesis concomitant with an enhanced cancer survival dependence on mid-step genes, a process we recently termed "Porphyrin Overdrive". Specifically, porphyrins build up in both lung cancer cells and stromal cells in the TME. Within the TME's stromal cells, evidence supports cancer-associated fibroblasts (CAFs) actively producing porphyrins through an imbalanced pathway. Conversely, normal tissues exhibit no porphyrin accumulation, and CAFs deprived of tumor cease porphyrin overproduction, indicating that both cancer and tumor-stromal porphyrin overproduction is confined to the cancer-specific tissue niche. The clinical relevance of our findings is implied by establishing a correlation between imbalanced porphyrin production and overall poorer survival in more aggressive cancers. These findings illuminate the anomalous porphyrin dynamics specifically within the tumor microenvironment, suggesting a potential target for therapeutic intervention.

Photodynamic therapy for cancer: mechanisms, photosensitizers, nanocarriers, and clinical studies

Photodynamic therapy (PDT) is a temporally and spatially precisely controllable, noninvasive, and potentially highly efficient method of phototherapy. The three components of PDT primarily include photosensitizers, oxygen, and light. PDT employs specific wavelengths of light to active photosensitizers at the tumor site, generating reactive oxygen species that are fatal to tumor cells. Nevertheless, traditional photosensitizers have disadvantages such as poor water solubility, severe oxygen-dependency, and low targetability, and the light is difficult to penetrate the deep tumor tissue, which remains the toughest task in the application of PDT in the clinic. Here, we systematically summarize the development and the molecular mechanisms of photosensitizers, and the challenges of PDT in tumor management, highlighting the advantages of nanocarriers-based PDT against cancer. The development of third generation photosensitizers has opened up new horizons in PDT, and the cooperation between nanocarriers and PDT has attained satisfactory achievements. Finally, the clinical studies of PDT are discussed. Overall, we present an overview and our perspective of PDT in the field of tumor management, and we believe this work will provide a new insight into tumor-based PDT.

Sequence-dependent effects of hematoporphyrin derivatives (HPD) photodynamic therapy and cisplatin on lung adenocarcinoma cells

BACKGROUND

Hematoporphyrin derivatives (HPD)-Photodynamic therapy (PDT) in combination with cisplatin (DDP) is an effective anticancer strategy. However, whether the order of combination affects efficacy has not been studied.

METHODS

The human lung adenocarcinoma (LUAD) A549 cells were used as the study subjects. After A549 cells were treated with a single medication (PDT/DDP) or a sequential combination (PDT + DDP / DDP + PDT), the cell viability was assayed using the cell counting kit-8 method. Hoechst staining, Annexin-V/propidium iodide (PI) double staining, western blotting, and a real-time quantitative polymerase chain reaction (RT-qPCR) were performed to examine the mechanisms behind the combined effects.

RESULTS

A synergistic impact between HPD-PDT and DDP was found. The cell viability in the PDT+DDP group was significantly lower than in the DDP+PDT group. A significant apoptotic profile and a high apoptotic rate were seen in the PDT + DDP group. The western blot showed that the expression levels of Bcl2-associated x(Bax) and cleaved-poly ADP-ribose polymerase (PARP) increased, and those of B-cell lymphoma-2 (Bcl-2) and Caspase-9 decreased in the PDT + DDP group. At the same time, the RT-qPCR revealed the upregulation of Bax and PARP mRNA and the downregulation of Bcl-2 and Caspase-9 mRNA.

CONCLUSION

The order of the combination therapy (PDT + DDP / DDP + PDT) was important. The HPD-PDT followed by DDP significantly inhibited LUAD cell viability, which may be related to the mitochondrial apoptotic pathway.

Enhanced systemic antitumor efficacy of PD-1/PD-L1 blockade with immunological response induced by photodynamic therapy

BACKGROUND

Photodynamic therapy (PDT) is an antitumor therapy and has traditionally been regarded as a localized therapy in itself. However, recent reports have shown that it not only exerts a direct cytotoxic effect on cancer cells but also enhances body's tumor immunity. We hypothesized that the immunological response induced by PDT could potentially enhance the efficacy of programmed death-1 (PD-1) / programmed death-ligand 1 (PD-L1) blockade.

METHODS

The cytotoxic effects of PDT on colon 26 cells were investigated in vitro using the WST assay. We investigated whether the antitumor effect of anti-PD-1 antibodies could be amplified by the addition of PDT. We performed combination therapy by randomly allocating tumor-bearing mice to four treatment groups: control, anti-PD-1 antibodies, PDT, and a combination of anti-PD-1 antibodies and PDT. To analyze the tumor microenvironment after treatment, the tumors were resected and pathologically evaluated.

RESULTS

The viability rate of colon 26 cells decreased proportionally with the laser dose. In vivo experiments for combined PDT and anti-PD-1 antibody treatment, combination therapy showed an enhanced antitumor effect compared with the control. Immunohistochemical findings of the tumor microenvironment 10 days after PDT indicated that the number of CD8+ cells, the area of Iba-1+ cells and the area expressing PD-L1 were significantly higher in tumors treated with combination therapy than in tumors treated with anti-PD-1 antibody alone, PDT alone, or the control.

CONCLUSIONS

PDT increased immune cell infiltration into the tumor microenvironment. The immunological response induced by PDT may enhance the efficacy of PD-1/PD-L1 blockade.

Long-term outcomes of PDT for centrally-located early lung cancers with tumor diameters > 2.0 cm

BACKGROUND

Photodynamic therapy (PDT) is used for the treatment of centrally-located early lung cancers (CLELCs) and is recommended for tumors ≤ 1.0 cm in diameter. We previously reported that PDT using talaporfin sodium, second-generation photosensitizer, for tumors > 1.0 cm but ≤ 2.0 cm in diameter was able to achieve a therapeutic outcome comparable to that of tumors with a diameter of ≤ 1.0 cm. However, the effectiveness of PDT using talaporfin sodium for tumors > 2.0 cm in diameter remains unclear. We conducted a retrospective analysis of cases in which PDT was performed for flat-type CLELCs with tumor diameters of > 2.0 cm.

METHODS

We retrospectively analyzed seven cases (eight lesions) with tumor diameters > 2.0 cm and no evidence of extracartilaginous invasion or lymph node metastasis.

RESULTS

All the patients underwent multiple PDT sessions. The PDT treatment results over the study period were partial response in one case (14.3 %), stable disease (SD) in three cases (42.9 %), and progressive disease (PD) in three cases (42.9 %). At the time of writing this report, five of seven cases (71.4 %) are still undergoing treatment. The duration of SD-the time from the start of treatment until the criteria for PD were met (SD or better maintained)-ranged from 7 to 52 months (mean, 25.3 months).

CONCLUSIONS

"Maintenance PDT" for CLELCs > 2.0 cm in diameter has the potential to inhibit tumor progression in the long term while maintaining quality of life, rather than simply aiming only for a quick radical cure.

Research progress of fullerenes and their derivatives in the field of PDT

In contemporary studies, the predominant utilization of C60 derivatives pertains to their role as photosensitizers or agents that scavenge free radicals. The intriguing coexistence of these divergent functionalities has prompted extensive investigation into water-soluble fullerenes. The photodynamic properties of these compounds find practical applications in DNA cleavage, antitumor interventions, and antibacterial endeavors. Consequently, photodynamic therapy is progressively emerging as a pivotal therapeutic modality within the biomedical domain, owing to its notable levels of safety and efficacy. The essential components of photodynamic therapy encompass light of the suitable wavelength, oxygen, and a photosensitizer, wherein the reactive oxygen species generated by the photosensitizer play a pivotal role in the therapeutic mechanism. The remarkable ability of fullerenes to generate singlet oxygen has garnered significant attention from scholars worldwide. Nevertheless, the limited permeability of fullerenes across cell membranes owing to their low water solubility necessitates their modification to enhance their efficacy and utilization. This paper reviews the applications of fullerene derivatives as photosensitizers in antitumor and antibacterial fields for the recent years.

Evaluating the photodynamic efficacy of nebulized curcumin-loaded liposomes prepared by thin-film hydration and dual centrifugation: In vitro and in ovo studies

Lung cancer, one of the most common causes of high mortality worldwide, still lacks appropriate and convenient treatment options. Photodynamic therapy (PDT) has shown promising results against cancer, especially in recent years. However, pulmonary drug delivery of the predominantly hydrophobic photosensitizers still represents a significant obstacle. Nebulizing DPPC/Cholesterol liposomes loaded with the photosensitizer curcumin via a vibrating mesh nebulizer might overcome current restrictions. In this study, the liposomes were prepared by conventional thin-film hydration and two other methods based on dual centrifugation. The liposomes' physicochemical properties were determined before and after nebulization, showing that liposomes do not undergo any changes. However, morphological characterization of the differently prepared liposomes revealed structural differences between the methods in terms of lamellarity. Internalization of curcumin in lung adenocarcinoma (A549) cells was visualized and quantified. The generation of reactive oxygen species because of the photoreaction was also proven. The photodynamic efficacy of the liposomal formulations was tested against A549 cells. They revealed different phototoxic responses at different radiant exposures. Furthermore, the photodynamic efficacy was investigated after nebulizing curcumin-loaded liposomes onto xenografted tumors on the CAM, followed by irradiation, and evaluated using positron emission tomography/computed tomography and histological analysis. A decrease in tumor metabolism could be observed. Based on the efficacy of curcumin-loaded liposomes in 2D and 3D models, liposomes, especially with prior film formation, can be considered a promising approach for PDT against lung cancer.

Three-dimensional printing of the human lung pleural cavity model for PDT malignant mesothelioma

OBJECTIVE

The primary aim was to investigate emerging 3D printing and optical acquisition technologies to refine and enhance photodynamic therapy (PDT) dosimetry in the management of malignant pleural mesothelioma (MPM).

MATERIALS AND METHODS

A rigorous digital reconstruction of the pleural lung cavity was conducted utilizing 3D printing and optical scanning methodologies. These reconstructions were systematically assessed against CT-derived data to ascertain their accuracy in representing critical anatomic features and post-resection topographical variations.

RESULTS

The resulting reconstructions excelled in their anatomical precision, proving instrumental translation for precise dosimetry calculations for PDT. Validation against CT data confirmed the utility of these models not only for enhancing therapeutic planning but also as critical tools for educational and calibration purposes.

CONCLUSION

The research outlined a successful protocol for the precise calculation of light distribution within the complex environment of the pleural cavity, marking a substantive advance in the application of PDT for MPM. This work holds significant promise for individualizing patient care, minimizing collateral radiation exposure, and improving the overall efficiency of MPM treatments.

Cutting-Edge Therapies for Lung Cancer

Lung cancer remains a formidable global health challenge that necessitates inventive strategies to improve its therapeutic outcomes. The conventional treatments, including surgery, chemotherapy, and radiation, have demonstrated limitations in achieving sustained responses. Therefore, exploring novel approaches encompasses a range of interventions that show promise in enhancing the outcomes for patients with advanced or refractory cases of lung cancer. These groundbreaking interventions can potentially overcome cancer resistance and offer personalized solutions. Despite the rapid evolution of emerging lung cancer therapies, persistent challenges such as resistance, toxicity, and patient selection underscore the need for continued development. Consequently, the landscape of lung cancer therapy is transforming with the introduction of precision medicine, immunotherapy, and innovative therapeutic modalities. Additionally, a multifaceted approach involving combination therapies integrating targeted agents, immunotherapies, or traditional cytotoxic treatments addresses the heterogeneity of lung cancer while minimizing its adverse effects. This review provides a brief overview of the latest emerging therapies that are reshaping the landscape of lung cancer treatment. As these novel treatments progress through clinical trials are integrated into standard care, the potential for more effective, targeted, and personalized lung cancer therapies comes into focus, instilling renewed hope for patients facing challenging diagnoses.

Clinical Practice of Photodynamic Therapy for Non-Small Cell Lung Cancer in Different Scenarios: Who Is the Better Candidate?

BACKGROUND

Photodynamic therapy (PDT) is a relatively safe and highly selectivity antitumor treatment, which might be increasingly used as a supplement to conventional therapies. A clinical overview and detailed comparison of how to select patients and lesions for PDT in different scenarios are urgently needed to provide a basis for clinical treatment.

SUMMARY

This review demonstrates the highlights and obstacles of applying PDT for lung cancer and underlines points worth considering when planning to initiate PDT. The aim was to make out the appropriate selection and help PDT develop efficacy and precision through a better understanding of its clinical use.

KEY MESSAGES

Increasing evidence supports the feasibility and safety of PDT in the treatment of non-small cell lung cancer. It is important to recognize the factors that influence the efficacy of PDT to develop individualized management strategies and implement well-designed procedures. These important issues should be worth considering in the present and further research.

Simulating photodynamic therapy for the treatment of glioblastoma using Monte Carlo radiative transport

Significance

Glioblastoma (GBM) is a rare but deadly form of brain tumor with a low median survival rate of 14.6 months, due to its resistance to treatment. An independent simulation of the INtraoperative photoDYnamic therapy for GliOblastoma (INDYGO) trial, a clinical trial aiming to treat the GBM resection cavity with photodynamic therapy (PDT) via a laser coupled balloon device, is demonstrated.

Aim

To develop a framework providing increased understanding for the PDT treatment, its parameters, and their impact on the clinical outcome.

Approach

We use Monte Carlo radiative transport techniques within a computational brain model containing a GBM to simulate light path and PDT effects. Treatment parameters (laser power, photosensitizer concentration, and irradiation time) are considered, as well as PDT's impact on brain tissue temperature.

Results

The simulation suggests that 39% of post-resection GBM cells are killed at the end of treatment when using the standard INDYGO trial protocol (light fluence = 200    J / cm 2 at balloon wall) and assuming an initial photosensitizer concentration of 5    μ M . Increases in treatment time and light power (light fluence = 400    J / cm 2 at balloon wall) result in further cell kill but increase brain cell temperature, which potentially affects treatment safety. Increasing the p hotosensitizer concentration produces the most significant increase in cell kill, with 61% of GBM cells killed when doubling concentration to 10    μ M and keeping the treatment time and power the same. According to these simulations, the standard trial protocol is reasonably well optimized with improvements in cell kill difficult to achieve without potentially dangerous increases in temperature. To improve treatment outcome, focus should be placed on improving the photosensitizer.

Conclusions

With further development and optimization, the simulation could have potential clinical benefit and be used to help plan and optimize intraoperative PDT treatment for GBM.

Current Advances in Photodynamic Therapy (PDT) and the Future Potential of PDT-Combinatorial Cancer Therapies

Photodynamic therapy (PDT) is a two-stage treatment that implies the use of light energy, oxygen, and light-activated compounds (photosensitizers) to elicit cancerous and precancerous cell death after light activation (phototoxicity). The biophysical, bioengineering aspects and its combinations with other strategies are highlighted in this review, both conceptually and as they are currently applied clinically. We further explore the recent advancements of PDT with the use of nanotechnology, including quantum dots as innovative photosensitizers or energy donors as well as the combination of PDT with radiotherapy and immunotherapy as future promising cancer treatments. Finally, we emphasize the potential significance of organoids as physiologically relevant models for PDT.

Phytosphingosine inhibits the growth of lung adenocarcinoma cells by inducing G2/M-phase arrest, apoptosis, and mitochondria-dependent pathway cell death in vitro and in vivo

In order to search for novel antitumor drugs with high efficiency and low toxicity, the anti-lung cancer activity of phytosphingosine was studied. Phytosphingosine is widely distributed in fungi, plants, animals, and has several biological activities, including anti-inflammation and anti-tumor. However, its anti-lung cancer activity needs to be further investigated. The effects and pharmacological mechanisms of phytosphingosine on lung cancer treatment were investigated both in vitro and in vivo. The results showed that phytosphingosine inhibited the growth of lung cancer cell lines. Phytosphingosine induced apoptosis through a mitochondria-mediated pathway, phytosphingosine arrested the cell cycle at the G2/M phase and induced apoptosis in a dose-dependent manner by increasing Bax/Bcl-2 ratio, which caused the decrease of mitochondrial membrane potential to promote the release of cytochrome C, caspase 9 and 3, and degrade PARP in A549 cells. The results showed that phytosphingosine could damage the mitochondrial functions, increase ROS levels, and arrest the cell cycle at the G2/M stages. Finally, phytosphingosine also inhibited the growth of tumor in mice. Taken together, phytosphingosine suppressed the growth of lung cancer cells both in vitro and in vivo and had potential application in the research and development of antitumor drugs. The aim of the present study was to explain the theoretical basis of phytosphingosine therapy for lung cancer and providing new possibilities for lung cancer treatment.

Dual-wavelength responsive CuS@COF nanosheets for high-performance photothermal/photodynamic combination treatments

Photothermal therapy (PTT) makes it difficult to achieve good performance on tumor treatments due to insufficient photothermal conversion efficiency, etc. Combining PTT with photodynamic therapy (PDT) and other therapeutic tools can significantly enhance the tumor-killing ability and has been widely used in the development of therapeutic platforms. Copper sulfide nanoparticle (CuS NP) photothermal reagents have the advantages of low toxicity and simple synthesis; therefore, combining CuS NPs with PDT photosensitizers is an effective strategy to construct a PTT/PDT combination therapeutic platform. However, PDT photosensitizers and photothermal agents generally assembled through hydrophobic interaction, suffer from low coating efficiency or the risk of drug leakage, thus seriously restricting their applications. To address these challenges, CuS NPs with excellent photothermal conversion performance were selected as the core material to prepare CuS@COF nanosheets through a dual-ligand assistant strategy with 4,7-bis(4-aminophenyl)-2,1,3-benzothiadiazole (BTD) and 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (TP). As a PTT/PDT combination therapeutic platform, CuS@COF nanosheets possess a porous TP-BDT-based COF shell, and it can sufficiently contact oxygen to provide high singlet oxygen (1O2) yield under 505 nm laser irradiation. Upon illumination with a 1064 nm laser, CuS@COF nanosheets can effectively convert the photon energy into thermal energy with a photothermal conversion efficiency of 63.4%. The results of the CCK8 experiment showed that the phototoxicity of the PTT/PDT combination treatment reached 85.1%, which was much higher than the effect of a single treatment. It was also confirmed in vivo that the tumor inhibition effect of the PDT/PTT combination treatment group was much greater than that of the single treatment group.

Exploring Thioxanthone Derivatives as Singlet Oxygen Photosensitizers for Photodynamic Therapy at the Near-IR Region

In the lowest excited triplet state, the excited photosensitizer reacts with tissue oxygen and forms reactive oxygen species (ROS), which kills tissue cells in photodynamic therapy (PDT). Metal-free thio-based pure organic molecules and analogous nucleobases can be used as photosensitizers for PDT applications. Using quantum chemical methods, we studied one- and two-photon optical absorptions, fluorescence, and other excited-state properties of substituted thioxanthone derivatives for their potential as photosensitizers for PDT. Our calculated values were compared with the available experimental data. The calculation of the intersystem crossing rate constant for these photosensitizers explains the high quantum yield of the formation of ROS, as reported experimentally. The excited triplet-state population of the photosensitizer occurs through the 1π-π* → 3n-π* channel of intersystem crossing and increases in the presence of halogen substitution.

Recent advances in fluorescence imaging-guided photothermal therapy and photodynamic therapy for cancer: From near-infrared-I to near-infrared-II

Phototherapy (including photothermal therapy, PTT; and photodynamic therapy, PDT) has been widely used for cancer treatment, but conventional PTT/PDT show limited therapeutic effects due to the lack of disease recognition ability. The integration of fluorescence imaging with PTT/PDT can reveal tumor locations in a real-time manner, holding great potential in early diagnosis and precision treatment of cancers. However, the traditional fluorescence imaging in the visible and near-infrared-I regions (VIS/NIR-I, 400-900 nm) might be interfered by the scattering and autofluorescence from tissues, leading to a low imaging resolution and high false positive rate. The deeper near-infrared-II (NIR-II, 1000-1700 nm) fluorescence imaging can address these interferences. Combining NIR-II fluorescence imaging with PTT/PDT can significantly improve the accuracy of tumor theranostics and minimize damages to normal tissues. This review summarized recent advances in tumor PTT/PDT and NIR-II fluorophores, especially discussed achievements, challenges and prospects around NIR-II fluorescence imaging-guided PTT/PDT for cancers.

Antileukemic potential of Nile blue-mediated photodynamic therapy on HL60 human myeloid leukemia cells

Background/aim

Photodynamic therapy (PDT) has received great attention over the past decade in the treatment of diseases such as leukemia which is a cancer of the blood and bone marrow cells that causes a significant number of deaths worldwide. In this study, it was aimed to investigate the effects of Nile blue-mediated PDT (NB-mediated PDT) on HL60 cells.

Materials and methods

The effect of NB-mediated PDT on cell proliferation was evaluated with cell volume analysis using flow cytometry at 24 h. Cell apoptosis, ROS production, mitochondrial membrane potential, and cell cycle analysis were evaluated using annexin V-FITC, H2DCFDA, JC-1, and PI staining, respectively, by flow cytometry and fluorescence microscopy. The morphological and ultrastructural analyses were examined by Giemsa staining and SEM. CD11b staining is used to determine the differentiation of leukemia cells.

Results

NB-mediated PDT induced an apoptotic response at 12.5 μM in HL60 cells. When Giemsa staining and SEM images were evaluated, apoptotic bodies, holes, and occasional folds were detected on the surfaces of cells in the NB-mediated PDT group.

Conclusion

The NB-mediated PDT had no effect on the differentiation of leukemia cells, but this therapy affects the growth of HL60 cells in vitro, which may provide a new idea for removing leukemic cells from bone marrow intended for autologous transplant.

Intraoperative photodynamic therapy for tracheal mass in non-small cell lung cancer: A case report

BACKGROUND

Tracheal neoplasms represent less than 0.1% of all malignancies and have no established treatment guidelines. Surgical resection with reconstruction is the primary treatment. This study demonstrates successful treatment of concurrent lung and tracheal tumors using surgical excision and intraoperative photodynamic therapy (PDT), highlighting the effectiveness and safety of this approach.

CASE SUMMARY

A 74-year-old male with a history of smoking and chronic obstructive pulmonary disease was diagnosed with tracheal squamous cell carcinoma and right lower lobe adenocarcinoma. A multidisciplinary team created a treatment plan involving tumor resection and PDT. The tracheal tumor was removed through a tracheal incision and this was followed by intraluminal PDT. The trachea was repaired and a right lower lobectomy was performed. The patient received a second PDT treatment postoperatively and was discharged 10 d after the tracheal surgery, without complications. He then underwent platinum-based chemotherapy for lymphovascular invasion of lung cancer. Three-month postoperative bronchoscopy revealed normal tracheal mucosa with a scar at the resection site and no evidence of tumor recurrence in the trachea or lung.

CONCLUSION

Our case of concurrent tracheal and lung cancers was successfully treated with surgical excision and intraoperative PDT which proved safe and effective in this patient.

Innovative Invasive Loco-Regional Techniques for the Treatment of Lung Cancer

Surgical resection is still the standard treatment for early-stage lung cancer. A multimodal treatment consisting of chemotherapy, radiotherapy and/or immunotherapy is advised for more advanced disease stages (stages IIb, III and IV). The role of surgery in these stages is limited to very specific indications. Regional treatment techniques are being introduced at a high speed because of improved technology and their possible advantages over traditional surgery. This review includes an overview of established and promising innovative invasive loco-regional techniques stratified based on the route of administration, including endobronchial, endovascular and transthoracic routes, a discussion of the results for each method, and an overview of their implementation and effectiveness.

Recent Advances in Green Metallic Nanoparticles for Enhanced Drug Delivery in Photodynamic Therapy: A Therapeutic Approach

Globally, cancer is one of the leading causes of death among men and women, it is characterized by the unregulated proliferation of tumor cells. Some of the common risk factors associated with cancer development include the consistent exposure of body cells to carcinogenic agents such as alcohol, tobacco, toxins, gamma rays and alpha particles. Besides the above-mentioned risk factors, conventional therapies such as radiotherapy, and chemotherapy have also been linked to the development of cancer. Over the past decade, tremendous efforts have been invested in the synthesis of eco-friendly green metallic nanoparticles (NPs), and their medical application. Comparatively, metallic NPs have greater advantages over conventional therapies. Additionally, metallic NPs can be functionalized with different targeting moieties e.g., liposomes, antibodies, folic acid, transferrin, and carbohydrates. Herein, we review and discuss the synthesis, and therapeutic potential of green synthesized metallic NPs for enhanced cancer photodynamic therapy (PDT). Finally, the advantages of green hybridized activatable NPs over conventional photosensitizers (PSs) and the future perspectives of nanotechnology in cancer research are discussed in the review. Furthermore, we anticipate that the insights offered in this review will inspire the design and development of green nano-formulations for enhanced image-guided PDT in cancer treatment.

Recent advances in the identification of biosynthetic genes and gene clusters of the polyketide-derived pathways for anthraquinone biosynthesis and biotechnological applications

Natural anthraquinones are represented by a large group of compounds. Some of them are widespread across the kingdoms, especially in bacteria, fungi and plants, while the others are restricted to certain groups of organisms. Despite the significant pharmacological potential of several anthraquinones (hypericin, skyrin and emodin), their biosynthetic pathways and candidate genes coding for key enzymes have not been experimentally validated. Understanding the genetic and epigenetic regulation of the anthraquinone biosynthetic gene clusters in fungal endophytes would help not only understand their pathways in plants, which ensure their commercial availability, but also favor them as promising systems for prospective biotechnological production.

Development of a new minimally invasive phototherapy for lung cancer using antibody-toxin conjugate

BACKGROUND

Photodynamic therapy (PDT) is a cancer-targeted treatment that uses a photosensitizer (PS) and laser irradiation. The effectiveness of current PDT using red light for advanced cancers is limited, because red light can only reach depths within a few millimeters. To enhance the antitumor effect for lung cancers, we developed a new phototherapy, intelligent targeted antibody phototherapy (iTAP). This treatment uses a combination of immunotoxin and a PS, mono-L-aspartyl chlorin e6 (NPe6).

METHODS

We examined whether cetuximab encapsulated in endosomes was released into the cytosol by PS in PDT under light irradiation. A431 cells were treated with fluorescein isothiocyanate-labeled cetuximab, NPe6, and light irradiation and were observed with fluorescence microscopy. We analyzed the cytotoxicity of saporin-conjugated cetuximab (IT-cetuximab) in A431, A549, and MCF7 cells and the antitumor effect in model A549-bearing mice in vivo using the iTAP method.

RESULTS

Fluorescent microscopy analysis showed that the photodynamic effect of NPe6 (20 μM) and light irradiation (37.6 J/cm² ) caused the release of cetuximab from the endosome into the cytosol. In vitro analysis demonstrated that the iTAP method enhanced the cytotoxicity of IT-cetuximab by the photodynamic effect. In in vivo experiments, compared with IT-cetuximab alone or PDT alone, the iTAP method using a low dose of IT-cetuximab showed the greatest enhancement of the antitumor effect.

CONCLUSIONS

Our study is the first report of the iTAP method using NPe6 for lung cancer cells. The iTAP method may become a new, minimally invasive treatment superior to current PDT methods.

Effect of Solubilizing Group on the Antibacterial Activity of Heptamethine Cyanine Photosensitizers

Antibiotic resistance of pathogenic bacteria dictates the development of novel treatment modalities such as antimicrobial photodynamic therapy (APDT) utilizing organic dyes termed photosensitizers that exhibit a high cytotoxicity upon light irradiation. Most of the clinically approved photosensitizers are porphyrins that are poorly excitable in the therapeutic near-IR spectral range. In contrast, cyanine dyes function well in the near-IR region, but their phototoxicity, in general, is very low. The introduction of iodine atoms in the cyanine molecules was recently demonstrated to greatly increase their phototoxicity. Herein, we synthesized a series of the new iodinated heptamethine cyanine dyes (ICy7) containing various solubilizing moieties, i.e., negatively charged carboxylic (ICy7COOH) and sulfonic (ICy7SO₃H) groups, positively charged triphenylphosphonium (ICy7PPh₃), triethylammonium (ICy7NEt₃) and amino (ICy7NH₂) groups, and neutral amide (ICy7CONHPr) group. The effect of these substituents on the photodynamic eradication of Gram-positive (S. aureus) and Gram-negative (E. coli and P. aeruginosa) pathogens was studied. Cyanine dyes containing the amide and triphenylphosphonium groups were found to be the most efficient for eradication of the investigated bacteria. These dyes are effective at low concentrations of 0.05 µM (33 J/cm²) for S. aureus, 50 µM (200 J/cm²) for E. coli, and 5 µM (100 J/cm²) for P. aeruginosa and considered, therefore, promising photosensitizers for APDT applications. The innovation of the new photosensitizers consisted of a combination of the heavy-atom effect that increases singlet oxygen generation with the solubilizing group's effect improving cell uptake, and with effective near-IR excitation. Such a combination helped to noticeably increase the APDT efficacy and should pave the way for the development of more advanced photosensitizers for clinical use.

Multifunctional AuPd-cluster nanotheranostic agents with a cascade self-regulating redox tumor-microenvironment for dual-photodynamic synergized enzyme catalytic therapy

Photodynamic therapy (PDT) has emerged as a promising strategy with higher selectivity and spatiotemporal control than conventional therapies. However, deep hypoxia in tumours has hampered the clinical use of PDT. In this study, a novel multifunctional cluster nanotheranostic agent (AuPd-BSA CN) was fabricated to generate a high amount of reactive oxygen species, regardless of oxygen dependence under 660 nm laser irradiation. The structure and properties of the AuPd-BSA CN were characterised using various technologies. The synthesised AuPd-BSA CN with high biocompatibility served as a superior photodynamic agent, showing prominent antitumour properties under laser irradiation. Additionally, the glucose oxidase-like activity of the AuPd-BSA CN synergistically enhanced the therapeutic performance. Notably, the intrinsic characteristics of the AuPd-BSA CN include dual-modal second near-infrared window fluorescence/photoacoustic imaging capabilities for monitoring and tracking the in vivo tumour therapeutic process. This work provides innovative insights into the AuPd-BSA CN as an "all-in-one" nanoplatform for cancer therapy.

Reaction mechanism of nanomedicine based on porphyrin skeleton and its application prospects

Research on porphyrin-based photosensitizing drugs is becoming increasingly popular. They possess unique diagnostic capabilities and therapeutic effects that have gained wide recognition in oncology drug development. In recent years, the rapid growth of nanotechnology has brought great hope for nanopharmaceutical formulations. By combining porphyrins with various nanomaterials, people have improved the properties of porphyrin compounds, making drug delivery easier. Porphyrin-based nanoparticles can enhance the effect of photodynamic therapy for cancer treatment, providing opportunities for achieving complex targeting strategies and versatility with promising applications in drug carriers, tumor imaging, and treatment. This paper reviews recent porphyrin nanodrugs, including inorganic-organic hybrid nanoparticles, nanomicelles, self-assembled nanoparticles, and combination therapeutic nanodrugs, and their actions and effects on cancer cells when performing photodynamic therapy. It also discusses the drawbacks as well as the prospects for development.

Terminalia chebula Polyphenol and Near-Infrared Dye-Loaded Poly(lactic acid) Nanoparticles for Imaging and Photothermal Therapy of Cancer Cells

Photothermal/photodynamic therapies (PTT/PDT) are multimodal approaches employing near-infrared (NIR) light-responsive photosensitizers for cancer treatment. In the current study, IR-775, a hydrophobic photosensitizer, was used in combination with a polyphenols (p)-rich ethyl acetate extract from Terminalia chebula to treat cancer. IR-775 dye and polyphenols were encapsulated in a poly(lactic acid) polymeric nanosystem (PpIR NPs) to increase the cell bioavailability. The hydrodynamic diameter of PpIR NPs is 142.6 ± 2 nm and exhibited physical stability. The nanosystem showed enhanced cellular uptake in a lung cancer cell line (A549). Cell cytotoxicity results indicate that PpIR NPs showed more than 82.46 ± 3% cell death upon NIR light treatment compared to the control groups. Both PDT and PTT generate reactive oxygen species (ROS) and cause hyperthermia, thereby enhancing cancer cell death. Qualitative and quantitative analyses have depicted that PpIR NPs with NIR light irradiation have decreased protein expression of HSP70 and PARP, and increased γ-H2AX, which collectively lead to cell death. After NIR light irradiation, the relative gene expression patterns of HSP70 and CDK2Na were also downregulated. Further, PpIR NPs uptake has been studied in 3D cells and in ovo bioimaging in zebrafish models. In conclusion, the PpIR NPs show good cancer cell cytotoxicity and present a potential nanosystem for bioimaging.

Photodynamic therapy of lung cancer, where are we?

Lung cancer remains the leading threat of death globally, killing more people than colon, breast, and prostate cancers combined. Novel lung cancer treatments are being researched because of the ineffectiveness of conventional cancer treatments and the failure of remission. Photodynamic therapy (PDT), a cancer treatment method that is still underutilized, is a sophisticated cancer treatment that shows selective destruction of malignant cells via reactive oxygen species production. PDT has been extensively studied in vitro and clinically. Various PDT strategies have been shown to be effective in the treatment of lung cancer. PDT has been shown in clinical trials to considerably enhance the quality of life and survival in individuals with incurable malignancies. Furthermore, PDT, in conjunction with the use of nanoparticles, is currently being researched for use as an effective cancer treatment, with promising results. PDT and the new avenue of nanoPDT, which are novel treatment options for lung cancer with such promising results, should be tested in clinical trials to determine their efficacy and side effects. In this review, we examine the status and future potentials of nanoPDT in lung cancer treatment.

Plasma Membrane-Targeted Photooxidant for Chemotherapy-Enhanced Lipid Peroxidation

Although photodynamic therapy (PDT) is a promising antitumor strategy for tumor treatment, the short half-life and the limited diffusion distance of reactive oxygen species (ROS) greatly hamper its antitumor efficacy. Moreover, tumor cells develop antioxidative microenvironments to weaken the oxidative damage caused by PDT. Herein, a plasma membrane-targeted photooxidant (designated as SCPP) is prepared by the self-assembly of a chimeric peptide (Pal-K(PpIX)-R4) and sorafenib. Plasma membrane-targeted SCPP could enhance lipid peroxidation (LPO) through in situ PDT upon light irradiation. Moreover, sorafenib-mediated chemotherapy could block cystine/glutamate antiporter xCT (SLC7A11) to inhibit the syntheses of intracellular GSH and glutathione peroxidase 4 (GPX4), which would destroy the antioxidant defense system of tumors. As a consequence, SCPP achieves a highly efficient tumor inhibition through enhanced PDT and ferroptosis therapy. This study might provide guidance for multisynergistic tumor therapy with a sophisticated mechanism under unfavorable conditions.

Targeting mitochondria in cancer therapy: Insight into photodynamic and photothermal therapies

Mitochondria are critical multifunctional organelles in cells that generate power, produce reactive oxygen species, and regulate cell survival. Mitochondria that are dysfunctional are eliminated via mitophagy as a way to protect cells under moderate stress and physiological conditions. However, mitophagy is a double-edged sword and can trigger cell death under severe stresses. By targeting mitochondria, photodynamic (PD) and photothermal (PT) therapies may play a role in treating cancer. These therapeutic modalities alter mitochondrial membrane potential, thereby affecting respiratory chain function and generation of reactive oxygen species promotes signaling pathways for cell death. In this regard, PDT, PTT, various mitochondrion-targeting agents and therapeutic methods could have exploited the vital role of mitochondria as the doorway to regulated cell death. Targeted mitochondrial therapies would provide an excellent opportunity for effective mitochondrial injury and accurate tumor erosion. Herein, we summarize the recent progress on the roles of PD and PT treatments in regulating cancerous cell death in relation to mitochondrial targeting and the signaling pathways involved.

YAP knockdown in combination with ferroptosis induction increases the sensitivity of HOS human osteosarcoma cells to Pyropheophorbide-α methyl ester-mediated photodynamic therapy

BACKGROUND AND AIMS

This study was designed to explore the effects of Yes-associated protein (YAP) knockdown on human osteosarcoma (HOS) cell sensitivity to Pyropheophorbide-α methyl ester-mediated photodynamic therapy (MPPa-PDT), and to assess how YAP silencing in combination with treatment with the ferroptosis inducer Erastin improves HOS cell sensitivity to MPPa-PDT in an effort to better clarify the molecular mechanisms underlying these phenotypes.

METHODS

At 12 h post-MPPa-PDT, Hoechst staining and flow cytometry were conducted to evaluate the apoptotic death of HOS cells. The expression of YAP in these cells at 12 h post-MPPa-PDT treatment was assessed via Western blotting and immunofluorescent staining. BODIPY^581/591-C11 was used to evaluate lipid peroxidation. Following shYAP lentiviral transduction, Western blotting was conducted to assess the expression of proteins associated with proliferation, apoptosis, and ferroptosis. EdU assays and clonogenic assays were performed to analyze cellular proliferation. Erastin-treated HOS cells were used to establish a ferroptosis model. Western blotting was used to measure ferroptosis-associated protein levels following shYAP and erastin treatment, while changes in proliferation and MDA levels in each group were examined using an MDA kit.

RESULTS

At 12 h post-MPPa-PDT, HOS cells exhibited apoptotic characteristics including nuclear fragmentation and pyknosis, with concomitant increases in apoptosis-associated proteins as detected via Western blotting and apoptotic induction as measured via flow cytometry. Phosphorylated YAP levels fell and non-phosphorylated YAP levels rose following such treatment. Transfection with shYAP was successful as a means of generating stable HOS cell lines, and Western blotting analyses of these cells revealed reductions in proteins associated with cellular proliferation together with the upregulation of apoptosis-related proteins.  MDA assays indicated that erastin combined with YAP knockdown enhanced the sensitivity of HOS cells to MPPa-PDT treatment.

CONCLUSIONS

These data indicate that ferroptosis and YAP knockdown can enhance osteosarcoma cell sensitivity to MPPa-PDT therapy.

Craft of Co-encapsulation in Nanomedicine: A Struggle To Achieve Synergy through Reciprocity

Achieving synergism, often by combination therapy via codelivery of chemotherapeutic agents, remains the mainstay of treating multidrug-resistance cases in cancer and microbial strains. With a typical core-shell architecture and surface functionalization to ensure facilitated targeting of tissues, nanocarriers are emerging as a promising platform toward gaining such synergism. Co-encapsulation of disparate theranostic agents in nanocarriers-from chemotherapeutic molecules to imaging or photothermal modalities-can not only address the issue of protecting the labile drug payload from a hostile biochemical environment but may also ensure optimized drug release as a mainstay of synergistic effect. However, the fate of co-encapsulated molecules, influenced by temporospatial proximity, remains unpredictable and marred with events with deleterious impact on therapeutic efficacy, including molecular rearrangement, aggregation, and denaturation. Thus, more than just an art of confining multiple therapeutics into a 3D nanoscale space, a co-encapsulated nanocarrier, while aiming for synergism, should strive toward achieving a harmonious cohabitation of the encapsulated molecules that, despite proximity and opportunities for interaction, remain innocuous toward each other and ensure molecular integrity. This account will inspect the current progress in co-encapsulation in nanocarriers and distill out the key points toward accomplishing such synergism through reciprocity.

Recent advances in noble metal complex based photodynamic therapy

Photodynamic therapy (PDT) utilizes light-activated photosensitizers (PSs) to generate toxic species for therapeutics. It has become an emerging solution for cancer treatment because of its specific spatiotemporal selectivity and minimal invasiveness. Noble metal (Ru, Ir and Pt) complexes are of increasing interest as photosensitizers for their excellent photophysical, photochemical, and photobiological properties. In this review, we highlight recent advancements in the development of noble metal complex photosensitizers for PDT during the last 5 years. We will summarize the design strategies of noble metal complexes for efficient and precise PDT, including increasing the light penetration depth, reducing the oxygen-dependent nature and improving target ability. Finally, we summarize recent efforts for the development of noble-based PSs and discuss the limitations of such PSs in clinical application and future perspectives in this field, such as the combination of PDT with other treatment modalities.

Tumor-responsive nanomedicine based on Ce3+-modulated up-/downconversion dual-mode emission for NIR-II imaging-guided dynamic therapy

Chemodynamic therapy (CDT) and photodynamic therapy (PDT) based on intratumoral generation of reactive oxygen species (ROS) have been playing crucial roles in conquering tumors. However, the above therapeutic methods are still constrained by the overexpressed tumor glutathione (GSH) and intrinsic tumor resistance to conventional organic photosensitizers. Herein, lanthanide-doped nanoparticles (LDNPs) were coated with inorganic bimetallic copper and manganese silicate nanospheres (CMSNs) and modified with sodium alginate (SA) for second near-infrared (NIR-II, 1000-1700 nm) imaging-guided CDT and PDT. Interestingly, cross-relaxation (CR) pathways between Ce³⁺ and Ho³⁺ and CR between Ce³⁺ and Er³⁺ are fully exploited to enable dual-mode upconversion (UC) and NIR-II downconversion (DC) emissions of LDNPs under 980 nm laser excitation. UC emission can induce CMSNs to produce toxic singlet oxygen (¹O₂) for PDT, and the released Mn²⁺ and Cu⁺ ions caused by GSH-induced degradation of CMSNs can react with endogenous H₂O₂ to produce hydroxyl radical (˙OH) for CDT. Significantly, the ultrabright NIR-II DC emission endows the systems with exceptional optical imaging capabilities. All results affirm the potency of such an "all in one" theranostic nanomedicine integrating PDT, CDT and remarkable NIR-II imaging abilities accompanied by the function of modulating tumor microenvironment in cancer theranostics.

Nanomaterials-based photosensitizers and delivery systems for photodynamic cancer therapy

The increasing cancer morbidity and mortality requires the development of high-efficiency and low-toxicity anticancer approaches. In recent years, photodynamic therapy (PDT) has attracted much attention in cancer therapy due to its non-invasive features and low side effects. Photosensitizer (PS) is one of the key factors of PDT, and its successful delivery largely determines the outcome of PDT. Although a few PS molecules have been approved for clinical use, PDT is still limited by the low stability and poor tumor targeting capacity of PSs. Various nanomaterial systems have shown great potentials in improving PDT, such as metal nanoparticles, graphene-based nanomaterials, liposomes, ROS-sensitive nanocarriers and supramolecular nanomaterials. The small molecular PSs can be loaded in functional nanomaterials to enhance the PS stability and tumor targeted delivery, and some functionalized nanomaterials themselves can be directly used as PSs. Herein, we aim to provide a comprehensive understanding of PDT, and summarize the recent progress of nanomaterials-based PSs and delivery systems in anticancer PDT. In addition, the concerns of nanomaterials-based PDT including low tumor targeting capacity, limited light penetration, hypoxia and nonspecific protein corona formation are discussed. The possible solutions to these concerns are also discussed.

Some Natural Photosensitizers and Their Medicinal Properties for Use in Photodynamic Therapy

Despite significant advances in early diagnosis and treatment, cancer is one of the leading causes of death. Photodynamic therapy (PDT) is a therapy for the treatment of many diseases, including cancer. This therapy uses a combination of a photosensitizer (PS), light irradiation of appropriate length and molecular oxygen. The photodynamic effect kills cancer cells through apoptosis, necrosis, or autophagy of tumor cells. PDT is a promising approach for eliminating various cancers but is not yet as widely applied in therapy as conventional chemotherapy. Currently, natural compounds with photosensitizing properties are being discovered and identified. A reduced toxicity to healthy tissues and a lower incidence of side effects inspires scientists to seek natural PS for PDT. In this review, several groups of compounds with photoactive properties are presented. The use of natural products has been shown to be a fruitful approach in the discovery of novel pharmaceuticals. This review focused on the anticancer activity of furanocoumarins, polyacetylenes, thiophenes, tolyporphins, curcumins, alkaloid and anthraquinones in relation to the light-absorbing properties. Attention will be paid to their phototoxic and anti-cancer effects on various types of cancer.

Ferroptosis triggered by dihydroartemisinin facilitates chlorin e6 induced photodynamic therapy by inhibiting GPX4 and enhancing ROS

Photodynamic therapy (PDT) is noninvasive, low toxicity, and photo-selective, but may be resisted by malignant cells. A previous study found chlorin e6 (Ce6) mediated PDT showed drug resistance in lung cancer cells (LLC), which may be associated with PDT-induced DNA damage response (DDR). DDR may up-regulate glutathione peroxidase 4 (GPX4), which in turn degrade ROS induced by PDT. However, dihydroartemisinin (DHA) was found to down-regulate GPX4. Accordingly, the DHA was hypothesized to improve the resistance to PDT. The present work explores the mechanism of Ce6 mediated drug resistance and reveals whether DHA can enhance the efficacy of PDT by suppressing GPX4. The in vitro experiments found Ce6 treatment did not inhibit the viability of LLC within 6 hr without inducing significant apoptosis, suggesting LLC were resistant to PDT. Further investigation demonstrated PDT could damage DNA and up-regulate GPX4, thus degrading the generated ROS. DHA effectively inhibited the viability of LLC and induced apoptosis. Importantly, DHA displayed a prominent inhibitory effect on the GPX4 expression and thereby triggered ferroptosis. Combining DHA with Ce6 for treatment of LLC resulted in the suppressed GPX4 and elevated ROS. Finally, the findings showed DHA combined with Ce6 exhibited superb anti-lung cancer efficacy. In summary, Ce6 PDT damages DNA, up-regulates GPX4 to degrade ROS, thereby inducing drug resistance. Down-regulation of GPX4 by DHA-triggered ferroptosis significantly enhances the efficacy of PDT. This study provides an outstanding theoretical basis for the regulation of the intratumoral redox system and improving PDT efficacy against lung cancer by herbal monomer DHA.

Platycodon D-induced A549 cell apoptosis through RRM1-regulated p53/VEGF/MMP2 pathway

BACKGROUND

Lung cancer is one of the leading causes of cancer-related deaths worldwide. Platycodin D (PD), a major pharmacological constituent from the Chinese medicinal herb named Platycodonis Radix, has shown potent anti-tumor activity. Also, it is also reported that PD could inhibit cellular growth in the non-small-cell lung carcinoma (NSCLC) A549 cell line. However, the underlying mechanism is not fully clarified.

METHODS

Cell proliferation was measured by MTT assay. Annexin V and propidium iodide (PI) assay were employed to study the apoptosis effects of PD on A549 cells. Western blot analysis was used to evaluate protein expression. Also, we used a siRNA against p53, as well as a plasmid-based RRM1 over-expression to investigate their functions.

RESULTS

It demonstrated PD inhibited A549 cell proliferation in a dose- and time-dependent manner. Further investigations showed that PD induced cell apoptosis, which was supported by dose-dependent and time-dependent caspase-3 activation and p53/VEGF/MMP2 pathway regulation. Also, PD demonstrated the inhibition effect of ribonucleotide reductase M1 (RRM1), whose role in various tumors is contradictory. Remarkably, in this work, RRM1 overexpression in A549 cells could have a negative impact on the regulation of the p53/VEGF/MMP2 pathway induced by PD treatment. Note as well that RRM1 overexpression also attenuated cell apoptosis and inhibition of cell proliferation of A549 treated with PD.

CONCLUSION

The results suggested that PD could inhibit A549 cell proliferation and induce cell apoptosis by regulating p53/VEGF/MMP2 pathway, in which RRM1 plays an important role directly.

Photodynamic Theranostics of Central Lung Cancer: Capabilities of Early Diagnosis and Minimally Invasive Therapy (Review)

The aim of the study was to assess the prospects for central lung cancer (CLC) screening using fluorescent diagnostics and its treatment by endobronchial photodynamic therapy (PDT). Bronchoscopic fluorescent diagnostics using chlorin e6 photosensitizers and a developed instrumental system enable to reveal tumor changes in large bronchi mucosa at early stages, and a developed PDT technique performed under fluorescent control helps achieve personalized treatment. Such an approach is considered as a theranostic technique - photodynamic theranostics. central lung cancer screening requires a fluorescent dye characterized by availability and can be used directly within the examination. Indocyanine green can be used as a dye, its peculiarity is the necessity to excite and record fluorescence in the near-infrared (NIR) wavelength band. First experiments using NIR bands to diagnose a bronchoscopic system showed the detectability of tumor areas using on-site bronchoscopic photodynamic theranostics, which consists in NIR imaging of tumor foci when a standard dose of indocyanine green is administered during the examination.

Conclusion

Further progress of early diagnostics and minimally invasive CLC therapy will be determined by the development of new photosensitizers, which should be characterized by a high absorption band in NIR area, quick accumulation in a tumor, high yield of single oxygen in NIR illumination, bright fluorescence, high potential in terms of the induction of an anti-tumor immune response.

Chlorin e6 mediated photodynamic therapy triggers resistance through ATM-related DNA damage response in lung cancer cells

OBJECTIVE

Photodynamic therapy (PDT) has emerged as a promising strategy in the treatment of malignant tumors due to its high selectivity, non-toxicity, and non-invasiveness. However, PDT can also induce DNA damage and subsequent repair response, which may reduce the efficacy of PDT. In the present study, we sought to explore the effect of chlorin e6 (Ce6)-mediated PDT on DNA damage and DNA damage response (DDR) in lung cancer cells. In addition, the effect of PDT combined with ATM inhibitor on molecules of DDR and the possibility of improving the efficacy of PDT were further investigated.

MATERIALS AND METHODS

In the in vitro study, lewis cells were submitted to Ce6 treatment (2, 4, 8, 16, 32 μg/mL). To determine the concentration of Ce6, uptake and toxicity of Ce6 mediated PDT were detected using flow cytometry (FACS), Confocal microscopy, and CCK-8. In the subsequent research, 8 μg/mL of Ce6 was the treatment condition for inducing PDT. The different post-irradiation placement times were further grouped under this condition (2, 4, 6, 12 h). Cellular reactive oxygen species (ROS), damage of DNA were measured by DCFH-DA probe, comet assay respectively. Then the expression of p-ATM, p53, and γ-H2A.X proteins related to DNA damage response, was detected by WB. The efficacy of Ce6 induced PDT was also demonstrated by Annexin-V/PI staining as well as the expression of PCNA, cleaved-caspase-3. On this basis, ATM inhibitor was applied to treat lewis cells combined with Ce6 (2, 4 h) to investigate whether the efficacy of PDT induced by Ce6 can be improved after the ATM-related DDR was blocked. The cell viability, apoptosis, and expression of associated proteins were assayed.

RESULTS

At 2-4 h after PDT treatment, ROS was dramatically elevated in lewis cells, DNA double-strand breaks (DDSB) occurred, as well as up-regulation of DDR proteins γ-H2A.X, p-ATM, and p53. At the same time, lewis cells did not undergo significant apoptosis. After ATM inhibition, the DDR was significantly blocked within 2-4 hours after Ce6 induced PDT, along with a pronounced decrease in cell viability followed by a prominent increase of apoptosis.

CONCLUSION

Ce6-mediated PDT generates ROS in a short period time, thus inducing DNA damage, ATM-related DDR as well as promoting resistance of lung cancer cells to PDT. Combining ATM inhibitor with PDT could effectively inhibit the DDR induced by PDT, thereby enhancing the efficacy. This study reveals a new resistance mechanism of PDT and proposes an intervention strategy.

Zinc pthalocyanine loaded poly (lactic acid) nanoparticles by double emulsion methodology for photodynamic therapy against 9 L/LacZ gliosarcoma cells

Development delivery systems, such as nanoparticles, represent a growing area in biomedical research. Nanoparticles (NP) were prepared using a double-emulsion method to load zinc(II) phthalocyanine (ZnPc). NP were obtained using poly (lactic acid) (PLA). ZnPc is a second generation of photosensitizer used in photodynamic therapy (PDT). ZnPc loaded PLA nanoparticles (NPLA-ZnPc) were prepared by double-emulsion method, characterized and available in cellular culture. The mean nanoparticle size presented particle size was 384.7 ± 84.2 nm with polydispersity index (PDI) of 0.150 ± 0.015, and the encapsulation efficiency was of 83%. The nanoparticle formulations presented negative zeta potential values (-27.5 ± 1.0 mV), explaining their colloidal stability. ZnPc loaded nanoparticles maintain its photophysical behavior after encapsulation. Photosensitizer release from nanoparticles was sustained over 168 h with a biphasic ZnPc release profile. An in vitro phototoxic effect in range of 80% was observed in 9 L/LacZ gliosarcoma cells at laser light doses (10 J cm^-2) with 3.0 µg mL^-1 of NPLA-ZnPc. All the physical-chemical, photophysical and photobiological measurements performed allow us to conclude that ZnPc loaded PLGA nanoparticles is a promising drug delivery system for PDT.

Photodynamic Therapy: A Compendium of Latest Reviews

Photodynamic therapy (PDT) is a promising therapy against cancer. Even though it has been investigated for more than 100 years, scientific publications have grown exponentially in the last two decades. For this reason, we present a brief compendium of reviews of the last two decades classified under different topics, namely, overviews, reviews about specific cancers, and meta-analyses of photosensitisers, PDT mechanisms, dosimetry, and light sources. The key issues and main conclusions are summarized, including ways and means to improve therapy and outcomes. Due to the broad scope of this work and it being the first time that a compendium of the latest reviews has been performed for PDT, it may be of interest to a wide audience.

MnO2-capped silk fibroin (SF) nanoparticles with chlorin e6 (Ce6) encapsulation for augmented photo-driven therapy by modulating the tumor microenvironment

Silk fibroin (SF), derived from Bombyx mori, is a category of fibrous protein with outstanding potential for applications in the biomedical and biotechnological fields. In spite of its many advantageous properties, the exploration of SF as a versatile nanodrug precursor for tumor therapy has still been restricted in recent years. Herein, a multifunctional SF-derived nanoplatform was facilely developed via encapsulating the photosensitizer chlorin e6 (Ce6) into MnO2-capped SF nanoparticles (NPs). SF@MnO2 nanocarriers were synthesized through a surface crystallization technique, using SF as a reductant and sacrificial template. Afterwards, Ce6 was covalently incorporated into the loose structure of the SF@MnO2 nanocarrier on the basis of adsorption to abundant peptide-binding sites. To modulate the tumor microenvironment (TME), SF@MnO2/Ce6 (SMC) NPs were capable of catalyzing the decomposition of H2O2 into O2, which can be converted into cytotoxic reactive oxygen species (ROS) during photodynamic therapy (PDT). Moreover, the MnO2 component was able to oxidize intracellular glutathione (GSH) into non-reducing glutathione disulfide (GSSG), and the consumption of GSH could significantly protect the local ROS from being reduced, which further augmented the therapeutic outcome of PDT. Via another angle, SMC NPs can produce strong hyperthermia under near-infrared (NIR) light activation, which was highly desirable for efficient photothermal therapy (PTT). Both in vitro and in vivo studies demonstrated the intense tumor inhibitory effects as a result of augmented PTT/PDT mediated by SMC NPs. We believe that this study may provide useful insights for employing SF-based nanocomposites for more medical applications in the near future.

Photodynamic Therapy for the Treatment and Diagnosis of Cancer-A Review of the Current Clinical Status

Photodynamic therapy (PDT) has been used as an anti-tumor treatment method for a long time and photosensitizers (PS) can be used in various types of tumors. Originally, light is an effective tool that has been used in the treatment of diseases for ages. The effects of combination of specific dyes with light illumination was demonstrated at the beginning of 20th century and novel PDT approaches have been developed ever since. Main strategies of current studies are to reduce off-target effects and improve pharmacokinetic properties. Given the high interest and vast literature about the topic, approval of PDT as the first drug/device combination by the FDA should come as no surprise. PDT consists of two stages of treatment, combining light energy with a PS in order to destruct tumor cells after activation by light. In general, PDT has fewer side effects and toxicity than chemotherapy and/or radiotherapy. In addition to the purpose of treatment, several types of PSs can be used for diagnostic purposes for tumors. Such approaches are called photodynamic diagnosis (PDD). In this Review, we provide a general overview of the clinical applications of PDT in cancer, including the diagnostic and therapeutic approaches. Assessment of PDT therapeutic efficacy in the clinic will be discussed, since identifying predictors to determine the response to treatment is crucial. In addition, examples of PDT in various types of tumors will be discussed. Furthermore, combination of PDT with other therapy modalities such as chemotherapy, radiotherapy, surgery and immunotherapy will be emphasized, since such approaches seem to be promising in terms of enhancing effectiveness against tumor. The combination of PDT with other treatments may yield better results than by single treatments. Moreover, the utilization of lower doses in a combination therapy setting may cause less side effects and better results than single therapy. A better understanding of the effectiveness of PDT in a combination setting in the clinic as well as the optimization of such complex multimodal treatments may expand the clinical applications of PDT.

Light Technology for Efficient and Effective Photodynamic Therapy: A Critical Review

Photodynamic therapy (PDT) is a cancer treatment with strong potential over well-established standard therapies in certain cases. Non-ionising radiation, localisation, possible repeated treatments, and stimulation of immunological response are some of the main beneficial features of PDT. Despite the great potential, its application remains challenging. Limited light penetration depth, non-ideal photosensitisers, complex dosimetry, and complicated implementations in the clinic are some limiting factors hindering the extended use of PDT. To surpass actual technological paradigms, radically new sources, light-based devices, advanced photosensitisers, measurement devices, and innovative application strategies are under extensive investigation. The main aim of this review is to highlight the advantages/pitfalls, technical challenges and opportunities of PDT, with a focus on technologies for light activation of photosensitisers, such as light sources, delivery devices, and systems. In this vein, a broad overview of the current status of superficial, interstitial, and deep PDT modalities-and a critical review of light sources and their effects on the PDT process-are presented. Insight into the technical advancements and remaining challenges of optical sources and light devices is provided from a physical and bioengineering perspective.

Overcoming barriers in photodynamic therapy harnessing nano-formulation strategies

Photodynamic therapy (PDT) has been extensively investigated for decades for tumor treatment because of its non-invasiveness, spatiotemporal selectivity, lower side-effects, and immune activation ability. It can be a promising treatment modality in several medical fields, including oncology, immunology, urology, dermatology, ophthalmology, cardiology, pneumology, and dentistry. Nevertheless, the clinical application of PDT is largely restricted by the drawbacks of traditional photosensitizers, limited tissue penetrability of light, inefficient induction of tumor cell death, tumor resistance to the therapy, and the severe pain induced by the therapy. Recently, various photosensitizer formulations and therapy strategies have been developed to overcome these barriers. Significantly, the introduction of nanomaterials in PDT, as carriers or photosensitizers, may overcome the drawbacks of traditional photosensitizers. Based on this, nanocomposites excited by various light sources are applied in the PDT of deep-seated tumors. Modulation of cell death pathways with co-delivered reagents promotes PDT induced tumor cell death. Relief of tumor resistance to PDT with combined therapy strategies further promotes tumor inhibition. Also, the optimization of photosensitizer formulations and therapy procedures reduces pain in PDT. Here, a systematic summary of recent advances in the fabrication of photosensitizers and the design of therapy strategies to overcome barriers in PDT is presented. Several aspects important for the clinical application of PDT in cancer treatment are also discussed.