Photosensitizers in prostate cancer therapy

A biochemistry-oriented drug design: synthesis, anticancer activity, enzymes inhibition, molecular docking studies of novel 1,2,4-triazole derivatives

In this study, we researched the reactions of 5-(5-bromofuran-2-yl)-4-methyl-1,2,4-triazole-3-thiol and 5-thiophene-(3-ylmethyl)-4R-1,2,4-triazole-3-thiols with some halogen-containing compounds, a number of new compounds were synthesized (1.1-1.5 and 2.1-2.8). These compounds showed excellent to good inhibitory activities on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. For obtaining the effects of these compounds on AChE and BChE enzymes were determined spectrophotometrically according to Ellman. IC50 values of these enzymes were ranging between 1.63 and 17.68 nM for AChE and 8.71 and 84.02 nM for BChE. After, prostate cancer is the second leading cause of cancer-related mortality for men over the age of 65 in developed countries. Current treatment options remain limited in the treatment of advanced-stage prostate cancer leading to biochemical recurrence in almost 40% of the patients. Therefore, there is an urgent need for development of novel therapeutic tools for treatment of prostate cancer patients. In this study, we aimed at analyzing the potential of all compounds against prostate cancer cells. We found that, of the tested compounds, 2.1, 2.2 and 2.3 showed significant cytotoxic activities against PC3 prostate cancer cells, although their effect on the viability of normal prostate cells was limited. These findings suggest their selective targeting potential for prostate cancer cells and offer them as candidate therapeutic agents against prostate cancer. The inhibitory activities of some chemical compounds, such as (1.1-1.5 and 2.1-2.8) were assessed by performing the molecular docking study in the presence of AChE, BChE and prostate cancer protein. MM/GBSA methods are calculated binding free energy. Finally, ADME/T analysis was performed to examine the drug properties of the 13 studied molecules.Communicated by Ramaswamy H. Sarma.

Cellular Mechanisms of Singlet Oxygen in Photodynamic Therapy

In this review, we delve into the realm of photodynamic therapy (PDT), an established method for combating cancer. The foundation of PDT lies in the activation of a photosensitizing agent using specific wavelengths of light, resulting in the generation of reactive oxygen species (ROS), notably singlet oxygen (1O2). We explore PDT's intricacies, emphasizing its precise targeting of cancer cells while sparing healthy tissue. We examine the pivotal role of singlet oxygen in initiating apoptosis and other cell death pathways, highlighting its potential for minimally invasive cancer treatment. Additionally, we delve into the complex interplay of cellular components, including catalase and NOX1, in defending cancer cells against PDT-induced oxidative and nitrative stress. We unveil an intriguing auto-amplifying mechanism involving secondary singlet oxygen production and catalase inactivation, offering promising avenues for enhancing PDT's effectiveness. In conclusion, our review unravels PDT's inner workings and underscores the importance of selective illumination and photosensitizer properties for achieving precision in cancer therapy. The exploration of cellular responses and interactions reveals opportunities for refining and optimizing PDT, which holds significant potential in the ongoing fight against cancer.

Adventures in Photodynamic Therapy: Location, Location, Location

In the context of photodynamic therapy, reports periodically turn up in journals where reviewers are apparently unacquainted with the essentials. Bizarre procedures and results can thereby appear. This appears to be a byproduct of the publishing industry, especially for some of the "pay to play" options.

Cancer phototherapy with nano-bacteria biohybrids

The utilization of light for therapeutic interventions, also known as phototherapy, has been extensively employed in the treatment of a wide range of illnesses, including cancer. Despite the benefits of its non-invasive nature, phototherapy still faces challenges pertaining to the delivery of phototherapeutic agents, phototoxicity, and light delivery. The incorporation of nanomaterials and bacteria in phototherapy has emerged as a promising approach that leverages the unique properties of each component. The resulting nano-bacteria biohybrids exhibit enhanced therapeutic efficacy when compared to either component individually. In this review, we summarize and discuss the various strategies for assembling nano-bacteria biohybrids and their applications in phototherapy. We provide a comprehensive overview of the properties and functionalities of nanomaterials and cells in the biohybrids. Notably, we highlight the roles of bacteria beyond their function as drug vehicles, particularly their capacity to produce bioactive molecules. Despite being in its early stage, the integration of photoelectric nanomaterials and genetically engineered bacteria holds promise as an effective biosystem for antitumor phototherapy. The utilization of nano-bacteria biohybrids in phototherapy is a promising avenue for future investigation, with the potential to enhance treatment outcomes for cancer patients.

Photodynamic Therapy-Adjunctive Therapy in the Treatment of Prostate Cancer

The alarming increase in the number of advanced-stage prostate cancer cases with poor prognosis has led to a search for innovative methods of treatment. In response to the need for implementation of new and innovative methods of cancer tissue therapy, we studied photodynamic action in excised prostate tissue in vitro as a model for photodynamic therapy. To ascertain the effects of photodynamic action in prostate tissue, Rose Bengal (0.01 to 0.05 mM) was used as a photosensitizer in the presence of oxygen and light to generate singlet oxygen in tissues in vitro. Five preset concentrations of Rose Bengal were chosen and injected into prostate tissue samples (60 samples with 12 replications for each RB concentration) that were subsequently exposed to 532 nm light. The effects of irradiation of the Rose Bengal infused tissue samples were determined by histopathological analysis. Histopathological examination of prostate samples subjected to photodynamic action revealed numerous changes in the morphology of the neoplastic cells and the surrounding tissues. We conclude that the morphological changes observed in the prostate cancer tissues were a result of the photogeneration of cytotoxic singlet oxygen. The tissue damage observed post photodynamic action offers an incentive for continued in vitro investigations and future in vivo clinical trials.

5-Aminolevulinic acid overcomes hypoxia-induced radiation resistance by enhancing mitochondrial reactive oxygen species production in prostate cancer cells

Background

The naturally occurring amino acid 5-aminolevulinic acid (5-ALA) is a precursor of protoporphyrin IX (PpIX) biosynthesised in the mitochondria. When accumulated PpIX is excited by light (wavelength of 625–635 nm), reactive oxygen species (ROS) are generated. Here, we investigated whether 5-ALA may increase the sensitisation of prostate cancer (PCA) cells to radiotherapy through the generation of ROS via its metabolite, PpIX.

Methods

Effect of 5-ALA on PC-3 and DU-145 PCA cell lines treated with ionising radiation (IR) was examined in vitro and in vivo with assessment by clonogenic assay, mitochondrial function and ROS production under normoxia or hypoxia condition.

Results

5-ALA enhanced intra-mitochondrial ROS production immediately after exposure to IR and decreased mitochondrial membrane potential via increase of intra-cellular PpIX. IR with 5-ALA induced mitochondrial dysfunction and increased ATP production, switching energy metabolism to the quiescence. Under hypoxic condition, ROS burst and mitochondrial dysfunction were induced by IR with 5-ALA resulting reducing cancer stemness and radiation resistance.

Conclusion

These results suggest that combined therapy with 5-ALA and radiation therapy is a novel strategy to improve the anti-cancer effects of radiation therapy for PCA.

Targeting Mitochondria for Cancer Photodynamic Therapy

Cancer remains a health-related concern globally from the ancient times till to date. The application of light to be used as therapeutic potential/agent has been used for several thousands of years. Photodynamic therapy (PDT) is a modern, non-invasive therapeutic modality for the treatment of various infections by bacteria, fungi, and viruses. Mitochondria are subcellular, double-membrane organelles that have the role in cancer and anticancer therapy. Mitochondria play a key role in regulation of apoptosis and these organelles produce most of the cell's energy which enhance its targeting objective. The role of mitochondria in anticancer approach is achieved by targeting its metabolism (glycolysis and TCA cycle) and apoptotic and ROS homeostasis. The role of mitochondria-targeted cancer therapies in photodynamic therapy have proven to be more effective than other similar non-targeting techniques. Particularly in PDT, mitochondria-targeting sensitizers are important as they have a crucial role in overcoming the hypoxia factor, resulting in high efficacy. IR-730 and IR-Pyr are the indocyine derivatives photosensitizers that play a crucial role in targeting mitochondria because of their better photostability during laser irradiation. Clinical and pre-clinical trials are going on this approach to target different solid tumors using mitochondrial targeted photodynamic therapy.

The emerging role of photoacoustic imaging in clinical oncology

Clinical oncology can benefit substantially from imaging technologies that reveal physiological characteristics with multiscale observations. Complementing conventional imaging modalities, photoacoustic imaging (PAI) offers rapid imaging (for example, cross-sectional imaging in real time or whole-breast scanning in 10-15 s), scalably high levels of spatial resolution, safe operation and adaptable configurations. Most importantly, this novel imaging modality provides informative optical contrast that reveals details on anatomical, functional, molecular and histological features. In this Review, we describe the current state of development of PAI and the emerging roles of this technology in cancer screening, diagnosis and therapy. We comment on the performance of cutting-edge photoacoustic platforms, and discuss their clinical applications and utility in various clinical studies. Notably, the clinical translation of PAI is accelerating in the areas of macroscopic and mesoscopic imaging for patients with breast or skin cancers, as well as in microscopic imaging for histopathology. We also highlight the potential of future developments in technological capabilities and their clinical implications, which we anticipate will lead to PAI becoming a desirable and widely used imaging modality in oncological research and practice.

Lanthanide-Doped Upconversion Luminescent Nanoparticles-Evolving Role in Bioimaging, Biosensing, and Drug Delivery

Upconverting luminescent nanoparticles (UCNPs) are "new generation fluorophores" with an evolving landscape of applications in diverse industries, especially life sciences and healthcare. The anti-Stokes emission accompanied by long luminescence lifetimes, multiple absorptions, emission bands, and good photostability, enables background-free and multiplexed detection in deep tissues for enhanced imaging contrast. Their properties such as high color purity, high resistance to photobleaching, less photodamage to biological samples, attractive physical and chemical stability, and low toxicity are affected by the chemical composition; nanoparticle crystal structure, size, shape and the route; reagents; and procedure used in their synthesis. A wide range of hosts and lanthanide ion (Ln³⁺) types have been used to control the luminescent properties of nanosystems. By modification of these properties, the performance of UCNPs can be designed for anticipated end-use applications such as photodynamic therapy (PDT), high-resolution displays, bioimaging, biosensors, and drug delivery. The application landscape of inorganic nanomaterials in biological environments can be expanded by bridging the gap between nanoparticles and biomolecules via surface modifications and appropriate functionalization. This review highlights the synthesis, surface modification, and biomedical applications of UCNPs, such as bioimaging and drug delivery, and presents the scope and future perspective on Ln-doped UCNPs in biomedical applications.

Combination of phototherapy with immune checkpoint blockade: Theory and practice in cancer

Immune checkpoint blockade (ICB) therapy has evolved as a revolutionized therapeutic modality to eradicate tumor cells by releasing the brake of the antitumor immune response. However, only a subset of patients could benefit from ICB treatment currently. Phototherapy usually includes photothermal therapy (PTT) and photodynamic therapy (PDT). PTT exerts a local therapeutic effect by using photothermal agents to generate heat upon laser irradiation. PDT utilizes irradiated photosensitizers with a laser to produce reactive oxygen species to kill the target cells. Both PTT and PDT can induce immunogenic cell death in tumors to activate antigen-presenting cells and promote T cell infiltration. Therefore, combining ICB treatment with PTT/PDT can enhance the antitumor immune response and prevent tumor metastases and recurrence. In this review, we summarized the mechanism of phototherapy in cancer immunotherapy and discussed the recent advances in the development of phototherapy combined with ICB therapy to treat malignant tumors. Moreover, we also outlined the significant progress of phototherapy combined with targeted therapy or chemotherapy to improve ICB in preclinical and clinical studies. Finally, we analyzed the current challenges of this novel combination treatment regimen. We believe that the next-generation technology breakthrough in cancer treatment may come from this combinational win-win strategy of photoimmunotherapy.

Synthesis of N-aryl-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridin-7-amines and their photodynamic properties in the human skin melanoma cell line G361

A small series of N-aryl-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridin-7-amines was synthesized from easily accessible 1-phenyl-1H-pyrazol-3-ol via 7-iodo-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridine and 7-iodo-4-methyl-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridine intermediates and their subsequent use in palladium catalyzed Buchwald-Hartwig cross-coupling reaction with various anilines. Majority of the compounds were not significantly cytotoxic to melanoma G361 cells in the dark up to 10 µM concentration, but their activity could be increased by irradiation with visible blue light (414 nm). The most active compound 10 possessed EC₅₀ values of 3.5, 1.6 and 0.9 µM in cells irradiated with 1, 5 and 10 J/cm², respectively. The treatment caused generation of reactive oxygen species in cells and extensive DNA damage, documented by the comet assay and by detection of phosphorylated histone H2A.X, followed by apoptotic cell death. Our results suggest that N-aryl-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridin-7-amines could serve as a potential source of photosensitizing compounds with anticancer activities.

Clinical Development of Metal Complexes as Photosensitizers for Photodynamic Therapy of Cancer

Cancer has emerged over the last decades as one of the deadliest diseases in the world. Among the most commonly used techniques (i.e. surgery, immunotherapy, radiotherapy or chemotherapy), increasing attention has been devoted towards photodynamic therapy. However, the vast majority of clinically applied photosensitizers are not ideal and associated with several limitations including poor aqueous solubility, poor photostability and slow clearance from the body, causing photosensitivity. In an effort to overcome these drawbacks, much attention has been devoted towards the incorporation of a metal ion. Herein, the clinical development of metal-containing compounds including Purlytin^® , Lutrin^® /Antrin^® , Photosens^® , TOOKAD^® soluble or TLD-1433 is critically reviewed.

Near infrared light activated upconversion nanoparticles (UCNP) based photodynamic therapy of prostate cancers: An in vitro study

Photodynamic therapy (PDT), has a potential to cure cancerous prostate tissue with minimal side effects. Traditional PDT, however, mostly utilized visible (VIS) light range with direct application of hydrophobic photosensitizers which may not be adequate in clinical practice for especially deep-seated cancer cells because of poor penetration of VIS wavelengths. Here, we report near infrared light (NIR) induced and dual photosensitizers (PS) encapsulated PDT strategy to reduce prostate cancer cells - PC3. The designed nanoplatform (MC540/ZnPc-UCNP@Au), in this study, include upconversion nanoparticles (UCNP) synthesis to convert NIR light into multiple VIS wavelengths, porous silica coating to upload dual photosensitizers (MC540/ZnPc), and gold (Au) functionalization to enhance PDT treatment. High chemical stabilization provided MC540/ZnPc-UCNP@Au show excellent biocompatibility, and efficient PDT treatment for prostate cancer cells. In fact, the fluorescence of the synthesized nanoplatforms, upon NIR light excitation, can produce considerable amount of ROS in 5 min, as it is well matched with the absorption of MC540, ZnPc and Au nanoparticles (np). In addition, the easy visualization of cellular internalized/adsorbed nanoplatforms reveal the in situ cell imaging possibility for diagnosis. Based on the evidence of the results, NIR light activated MC540/ZnPc-UCNP@Au may offer a PDT technique for the treatment of prostate cancer.

Minimally invasive magnetic resonance image-guided prostate interventions

Whole gland prostate cancer treatment, i.e. radical prostatectomy or radiation therapy, is highly effective but also comes with a significant impact on quality of life and possible overtreatment in males with low to intermediate risk disease. Minimal-invasive treatment strategies are emerging techniques. Different sources of energy are used to aim for targeted treatment in order to reduce treatment-related complications and morbidity. Imaging plays an important role in targeting and monitoring of treatment approaches preserving parts of the prostatic tissue. Multiparametric magnetic resonance imaging (mpMRI) is widely used during image-guided interventions due to the multiplanar and real-time anatomical imaging while providing an improved treatment accuracy. This review evaluates the available image-guided prostate cancer treatment options using MRI or magnetic resonance imaging/transrectal ultrasound (MRI/TRUS)-fusion guided imaging. The discussed minimal invasive image-guided prostate interventions may be considered as safe and feasible partial gland ablation in patients with (recurrent) prostate cancer. However, most studies focusing on minimally invasive prostate cancer treatments only report early stages of research and subsequent high-level evidence is still needed. Ensuring a safe and appropriate utilization in patients that will benefit the most, and applied by physicians with relevant training, has become the main challenge in minimally invasive prostate cancer treatments.

Photodynamic therapy of prostate cancer using porphyrinic formulations

Prostate cancer (PCa) is the second most frequent cancer diagnosed in men worldwide. Among the common treatment options, photodynamic therapy (PDT) is being considered a promising local therapy to treat this cancer. Although PDT is an established treatment modality approved for several types of cancer, the low solubility, the reduced tumor selectivity, the absorption in the therapeutic window and the poor clearance from the body of the currently approved photosensitizers (PS) hampers its wide clinical application. In this regard, herein we synthesized three fluorinated porphyrinoid derivatives and entrapped them into polyvinylpyrrolidone (PVP) to prevent their aggregation and preserve their desirable photophysical properties under the physiological environment. In vitro studies revealed the negligible dark cytotoxicity of all PVP formulations (PS1@PVP, PS2@PVP and PS3@PVP) at the tested concentrations (5.0 to 20 μM), but also confirmed the significant photodynamic effect of PS2@PVP and PS3@PVP towards the PCa cell line PC-3, upon red light irradiation at an irradiance of 17.6 mW.cm^-2. To provide insight into the underlying mechanisms of cell death under PDT treatment induced by PS2@PVP and PS3@PVP, their intracellular localization in PC-3 cells was firstly investigated by confocal microscopy. Since both PS2@PVP and PS3@PVP nanoparticles were mainly localized in mitochondria, the involvement of this organelle in PDT-induced apoptosis mediated by both formulations was further explored. Western blot analysis revealed that PDT treatment of PC-3 cells with either PS2@PVP or PS3@PVP resulted in the reduction of the expression level of the anti-apoptotic protein Bcl-2. As the photodamage to Bcl-2 after PDT with PS2@PVP and PS3@PVP was accompanied by the further activation of pro-caspase-3, we assumed that upon irradiation the photogenerated reactive oxygen species (ROS) were able to activate a caspase-dependent apoptotic response as a consequence of a post-mitochondrial event. Taken together, these findings demonstrate that among the tested fluorinated porphyrinoids, PS2@PVP and, particularly, PS3@PVP, are significantly more effective in overall PC-3 cell killing than PS1@PVP, thus highlighting their great potential as therapeutic agents for PCa.

Novel amphiphilic fluorine-containing nanocarriers for oxygen self-sufficiency "AND" GSH depletion sequentially to enhance photodynamic therapy

In order to maximize the retention of the photodynamic therapy (PDT) efficacy, while avoiding the dilemma of hypoxia and high reducing substances in tumor tissue, fluoropolymers were synthesized in a simple and effective methods. Fluorous effect with good oxygen carrying capacity was endowed by the fluorine-containing section in fluoropolymers and the perfluorodecalin (PFD) together, the reaction site with GSH was provided by the disulfide bond, which enhanced PDT efficiency through the sequential "AND" logic gate design. Two kind of fluorine-containing nanocarriers (M-Ce6 and E-Ce6) were obtained by solvent evaporation or ultrasound emulsification with PFD, respectively. In vitro, both of them showed promising high ROS generation under photoirradiation. Benefiting by cavitation effects, E-Ce6 had a more significant statistical difference in cellular uptake. Furthermore, the cells incubating with E-Ce6 hardly were noticed that the hypoxia signal appeared under hypoxia, while reducing the intracellular GSH content by more than 15%. Through the sequential "AND" logic gate design, ROS production even under hypoxia and GSH conditions of E-Ce6 was also almost 1.5 times that of Ce6 under normoxia. Enhancing effect of E-Ce6 was 13.47 times and 6.85 times, while selectivity ratio reached 5.13 times and 4.81 times compared with Ce6 and M-Ce6. The two-pronged strategy showed a high potential for delivering the Ce6 to deep inside of cancer cells and killing it in the simulated tumor by PDT. These above results demonstrated the potential of E-Ce6, as oxygen self-sufficiency and GSH depletion nanocarriers for combined enhancement of photodynamic therapy.

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.

Prostate minimally invasive procedures: complications and normal vs. abnormal findings on multiparametric magnetic resonance imaging (mpMRI)

Minimally invasive alternatives to traditional prostate surgery are increasingly utilized to treat benign prostatic hyperplasia and localized prostate cancer in select patients. Advantages of these treatments over prostatectomy include lower risk of complication, shorter length of hospital stay, and a more favorable safety profile. Multiparametric magnetic resonance imaging (mpMRI) has become a widely accepted imaging modality for evaluation of the prostate gland and provides both anatomical and functional information. As prostate mpMRI and minimally invasive prostate procedure volumes increase, it is important for radiologists to be familiar with normal post-procedure imaging findings and potential complications. This paper reviews the indications, procedural concepts, common post-procedure imaging findings, and potential complications of prostatic artery embolization, prostatic urethral lift, irreversible electroporation, photodynamic therapy, high-intensity focused ultrasound, focal cryotherapy, and focal laser ablation.

Focal therapy for primary and salvage prostate cancer treatment: a narrative review

Despite innovations in surgical technology and advancements in radiation therapy, radical treatments for clinically localized prostate cancer are associated with significant patient morbidity, including both urinary and sexual dysfunction. This has created a vital need for therapies and management strategies that provide an acceptable degree of oncologic efficacy while mitigating these undesirable side effects. Successful developments in screening approaches and advances in prostate imaging have allowed clinicians to identify, localize, and more precisely target early cancers. This has afforded urologists with an important opportunity to develop and employ focal ablation techniques that selectively destroy tumors while preserving the remainder of the gland, thus avoiding detrimental treatment effects to surrounding sensitive structures. A lack of high-level evidence supporting such an approach had previously hindered widespread adoption of focal treatments, but there are now numerous published clinical trials which have sought to establish benchmarks for safety and efficacy. As the clinical evidence supporting a potential role in prostate cancer treatment begins to accumulate, there has been a growing acceptance of focal therapy in the urologic oncology community. In this narrative review article, we describe the techniques, advantages, and side effect profiles of the most commonly utilized focal ablative techniques and analyze published clinical trial data supporting their evolving role in the prostate cancer treatment paradigm.

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.

Insights on the polypyrrole based nanoformulations for photodynamic therapy

This review is written to endow updated information on polypyrrole based photosensitizers for the treatment of deadly diseases such as cancer and microbial infection. Tetrapyrrolic macromolecules such as porphyrins and phthalocyanines hold unique photophysical properties which make them very useful compounds for various biomedical applications. Besides their properties, they also have some limitations such as low water solubility, bioavailability, biocompatibility and lack of specificity, etc. Researchers are trying to overcome these limitations by incorporating photosensitizers into the different types of nanoparticles and improve the quality of photodynamic therapy. We have contributed to this field by synthesizing and developing polypyrrolic photosensitizer based nanoparticles for potential applications in antimicrobial and anticancer photodynamic activity. Throughout this review, newly synthesized and existing PSs conjugated/encapsulated/doped/incorporated with nanoparticles are emphasized, which are essential for current and future research themes. Also in this review, we briefly summarized the research work carried over the past few years by considering the porphyrin based photosensitizers as alternative therapeutic entities for the treatment of microbial infections, cancers, and many other diseases.

Considerations and Technical Pitfalls in the Employment of the MTT Assay to Evaluate Photosensitizers for Photodynamic Therapy

Photodynamic therapy (PDT) combines light, a photosensitizing chemical substance, and molecular oxygen to elicit cell death and is employed in the treatment of a variety of diseases, including cancer. The development of PDT treatment strategies requires in vitro assays to develop new photosensitizers. One such assay is the MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide developed in 1983 and widely used in PDT studies. Despite the exponential growth in the number of publications, a uniform MTT protocol for use in the PDT area is lacking. Herein, we list and standardize the conditions to evaluate the photosensitizer methylene blue (MB) in glioblastoma and neuroblastoma cell lines. In addition, we review technical pitfalls and identify several variables that must be taken into consideration in order to provide accurate results with MTT. We conclude that for each cell line we must have a dose-response curve using the MTT assay and good controls for the standardization. Additionally, the optimal values of the time and cell density must be in the linear range of the curve to avoid errors. We describe all relevant points and outline the best normalization techniques to observe the differences between treatments.

Photodynamic therapy with a new bacteriochlorin derivative: Characterization and in vitro studies

Photodynamic therapy presents a therapeutic choice that can be utilized to treat diverse neoplasms. In this technique, the critical element is a photosensitive molecule that absorbs light energy and transfers it to molecular oxygen or biological molecules to form reactive oxygen species, thus inducing irreversible damage to target cells and ultimately leading to cell death. Bacteriochlorin derivatives are employed as photosensitizers (PSs), possessing light-absorbing capacity in the near-infrared region. The objective of this study was to prepare a semi-synthetic bacteriochlorin from Rhodopseudomonas faecalis and adding Trizma® to improve solubility. Cell viability tests, flow cytometry (apoptotic and necrotic cells were identified by Annexin V and propidium iodide), and confocal microscopy were used to evaluate the photoactivity of bacteriochlorin-Trizma (Bchl-T) in fibroblast (HFF-1-control cells) and breast cancer (MCF-7 cells-target cells) cells. At concentrations above 0.5 μM, Bchl-T demonstrated 80 % cell death, presenting the highest PS interaction (via fluorescence microscopy) with lysosomes, mitochondria, and the endoplasmic reticulum; the cell death type was revealed as apoptosis (via cytometry). Our findings indicated the suitability of Bchl-T for future application in photodynamic therapy against cancer cells by inducing apoptosis.

FAP-Targeted Photodynamic Therapy Mediated by Ferritin Nanoparticles Elicits an Immune Response against Cancer Cells and Cancer Associated Fibroblasts

Cancer-associated fibroblasts (CAFs) are present in many types of tumors and play a pivotal role in tumor progression and immunosuppression. Fibroblast-activation protein (FAP), which is overexpressed on CAFs, has been indicated as a universal tumor target. However, FAP expression is not restricted to tumors, and systemic treatment against FAP often causes severe side effects. To solve this problem, a photodynamic therapy (PDT) approach was developed based on ZnF₁₆Pc (a photosensitizer)-loaded and FAP-specific single chain variable fragment (scFv)-conjugated apoferritin nanoparticles, or αFAP-Z@FRT. αFAP-Z@FRT PDT efficiently eradicates CAFs in tumors without inducing systemic toxicity. When tested in murine 4T1 models, the PDT treatment elicits anti-cancer immunity, causing suppression of both primary and distant tumors, i.e. abscopal effect. Treatment efficacy is enhanced when αFAP-Z@FRT PDT is used in combination with anti-PD1 antibodies. Interestingly, it is found that the PDT treatment not only elicits a cellular immunity against cancer cells, but also stimulates an anti-CAFs immunity. This is supported by an adoptive cell transfer study, where T cells taken from 4T1-tumor-bearing animals treated with αFAP PDT retard the growth of A549 tumors established on nude mice. Overall, our approach is unique for permitting site-specific eradication of CAFs and inducing a broad spectrum anti-cancer immunity.

Pathological and Pharmacological Roles of Mitochondrial Reactive Oxygen Species in Malignant Neoplasms: Therapies Involving Chemical Compounds, Natural Products, and Photosensitizers

Oxidative stress plays an important role in cellular processes. Consequently, oxidative stress also affects etiology, progression, and response to therapeutics in various pathological conditions including malignant tumors. Oxidative stress and associated outcomes are often brought about by excessive generation of reactive oxygen species (ROS). Accumulation of ROS occurs due to dysregulation of homeostasis in an otherwise strictly controlled physiological condition. In fact, intracellular ROS levels are closely associated with the pathological status and outcome of numerous diseases. Notably, mitochondria are recognized as the critical regulator and primary source of ROS. Damage to mitochondria increases mitochondrial ROS (mROS) production, which leads to an increased level of total intracellular ROS. However, intracellular ROS level may not always reflect mROS levels, as ROS is not only produced by mitochondria but also by other organelles such as endoplasmic reticulum and peroxisomes. Thus, an evaluation of mROS would help us to recognize the biological and pathological characteristics and predictive markers of malignant tumors and develop efficient treatment strategies. In this review, we describe the pathological significance of mROS in malignant neoplasms. In particular, we show the association of mROS-related signaling in the molecular mechanisms of chemically synthesized and natural chemotherapeutic agents and photodynamic therapy.

Photodynamic therapy induces autophagy-mediated cell death in human colorectal cancer cells via activation of the ROS/JNK signaling pathway

Evidence has shown that m-THPC and verteporfin (VP) are promising sensitizers in photodynamic therapy (PDT). In addition, autophagy can act as a tumor suppressor or a tumor promoter depending on the photosensitizer (PS) and the cancer cell type. However, the role of autophagy in m-THPC- and VP-mediated PDT in in vitro and in vivo models of human colorectal cancer (CRC) has not been reported. In this study, m-THPC-PDT or VP-PDT exhibited significant phototoxicity, inhibited proliferation, and induced the generation of large amounts of reactive oxygen species (ROS) in CRC cells. From immunoblotting, fluorescence image analysis, and transmission electron microscopy, we found extensive autophagic activation induced by ROS in cells. In addition, m-THPC-PDT or VP-PDT treatment significantly induced apoptosis in CRC cells. Interestingly, the inhibition of m-THPC-PDT-induced autophagy by knockdown of ATG5 or ATG7 substantially inhibited the apoptosis of CRC cells. Moreover, m-THPC-PDT treatment inhibited tumorigenesis of subcutaneous HCT116 xenografts. Meanwhile, antioxidant treatment markedly inhibited autophagy and apoptosis induced by PDT in CRC cells by inactivating JNK signaling. In conclusion, inhibition of autophagy can remarkably alleviate PDT-mediated anticancer efficiency in CRC cells via inactivation of the ROS/JNK signaling pathway. Our study provides evidence for the therapeutic application of m-THPC and VP in CRC.

Atorvastatin Enhances Effects of Radiotherapy on Prostate Cancer Cells and Xenograft Tumor Mice Through Triggering Interaction Between Bcl-2 and MSH2

BACKGROUND Prostate cancer (PCa) is considered to be the 4th most common cancer in males in the world. This study aimed to explore effects of atorvastatin on colony formation of PCa cells and radio-resistance of xenograft tumor models. MATERIAL AND METHODS PCa cell lines, including PC3, DU145, and Lncap, were treated with irradiation (4 Gy) and/or atorvastatin (6 μg/mL). Cells were divided into tumor cell group, irradiation treatment group (IR group) and irradiation+atorvastatin treatment group (IR-AS group). Xenograft tumor mouse model was established. Plate clone formation assay (multi-target/single-hit model) was conducted to evaluate colony formation. Flow cytometry analysis was employed to detect apoptosis. Interaction between Bcl-2 and MSH2 was evaluated with immuno-fluorescence assay. RESULTS According to the plate colony formation assay and multi-target/single-hit model, IR-treatment significantly suppressed colony formation in PCa cells (including PC3, DU145, and Lncap cells) compared to no-IR treated cells (P<0.05). Atorvastatin remarkably enhanced inhibitive effects of irradiation on colony formation of PCa cells (P<0.05), however, the IR+AS group demonstrated no effects on apoptosis, comparing to IR group (P>0.05). Atorvastatin administration (IR+AS group) significantly reduced tumor size of IR-treated PCa cells-induced xenograft tumor mice (P<0.05). Bcl-2 interacted with MSH2 both in tumor tissues of xenograft tumor mice. CONCLUSIONS Atorvastatin administration inhibited colony formation in PCa cells and enhanced effects of radiotherapy on tumor growth of xenograft tumor mice, which might be associated with interaction between Bcl-2 and MSH2 molecule.

Oxime-based 19-nortestosterone-pheophorbide a conjugate: bimodal controlled release concept for PDT

Photodynamic therapy has become a feasible direction for the treatment of both malignant and non-malignant diseases. It has been in the spotlight since FDA regulatory approval was granted to several photosensitizers worldwide. Nevertheless, there are still strong limitations in the targeting specificity that is vital to prevent systemic toxicity. Here, we report the synthesis and biological evaluation of a novel bimodal oxime conjugate composed of a photosensitizing drug, red-emitting pheophorbide a, and nandrolone (NT), a steroid specifically binding the androgen receptor (AR) commonly overexpressed in various tumors. We characterized the physico-chemical properties of the NT-pheophorbide a conjugate (NT-Pba) and singlet oxygen generation. Because light-triggered therapies have the potential to provide important advances in the treatment of hormone-sensitive cancer, the biological potential of this novel specifically-targeted photosensitizer was assessed in prostatic cancer cell lines in vitro using an AR-positive (LNCaP) and an AR-negative/positive cell line (PC-3). U-2 OS cells, both with and without stable AR expression, were used as a second cell line model. Interestingly, we found that the NT-Pba conjugate was not only photodynamically active and AR-specific, but also that its phototoxic effect was more pronounced compared to pristine pheophorbide a. We also examined the intracellular localization of NT-Pba. Live-cell fluorescence microscopy provided clear evidence that the NT-Pba conjugate localized in the endoplasmic reticulum and mitochondria. Moreover, we performed a competitive localization study with the excess of nonfluorescent NT, which was able to displace fluorescent NT-Pba from the cell interior, thereby further confirming the binding specificity. The oxime ether bond degradation was assayed in living cells by both real-time microscopy and a steroid receptor reporter assay using AR U-2 OS cells. Thus, NT-Pba is a promising candidate for both the selective targeting and eradication of AR-positive malignant cells by photodynamic therapy.

SP1-mediated upregulation of lncRNA SNHG4 functions as a ceRNA for miR-377 to facilitate prostate cancer progression through regulation of ZIC5

BACKGROUND/AIMS

Long noncoding RNAs (lncRNAs) have been demonstrated to serve distinct roles in human tumorigenesis. Previous studies have found that lncRNA small nucleolar RNA host gene 4 (SNHG4) was dysregulated in several tumors. However, the expression, clinical significances, and action mechanisms of SNHG4 in prostate cancer (PCa) are still unclear.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to detect SNHG4 expression in tissue samples and PCa cells. Cell counting kit-8, 5-ethynyl-2'-deoxyuridine, clonogenic formation, wound-healing, and transwell invasion assays were, respectively, used to evaluate cell proliferation, colony formation ability, migration, and invasion. Flow cytometric analysis was applied to assess cell apoptosis. Chromatin immunoprecipitation assays were conducted to determine the binding between SP1 and SNHG4 promoter. Luciferase reporter assay, qRT-PCR, and western blot analysis were carried out to explore and confirm the interaction among SNHG4, miR-377, and ZIC5.

RESULTS

SNHG4 was highly expressed in PCa and its upregulation was induced by transcription factor SP1. The high levels of SNHG4 were distinctly associated with tumor stage, lymph node metastasis, and reduced overall survival of patients with PCa. SNHG4 knockdown inhibited the growth, migration, and invasion of PCa cells. In addition, miR-377 was a target of SNHG4 and ZIC5 was a target gene of miR-377 in PCa. SNHG4 promoted ZIC5-mediated growth and metastasis through modulating miR-377.

CONCLUSION

Our findings illuminate how SNHG4 formed a regulatory network to display a tumor-promotive effect in PCa and revealed that SNHG4 may be a novel therapeutic target and prognostic marker for patients with PCa.

X-ray tomography of cryopreserved human prostate cancer cells: mitochondrial targeting by an organoiridium photosensitiser

Abstract

The organoiridium complex Ir[(C,N)₂(O,O)] (1) where C, N = 1-phenylisoquinoline and O,O = 2,2,6,6-tetramethyl-3,5-heptanedionate is a promising photosensitiser for Photo-Dynamic Therapy (PDT). 1 is not toxic to cells in the dark. However, irradiation of the compound with one-photon blue or two-photon red light generates high levels of singlet oxygen (¹O₂) (in Zhang et al. Angew Chem Int Ed Engl 56 (47):14898-14902 10.1002/anie.201709082,2017), both within cell monolayers and in tumour models. Moreover, photo-excited 1 oxidises key proteins, causing metabolic alterations in cancer cells with potent antiproliferative activity. Here, the tomograms obtained by cryo-Soft X-ray Tomography (cryo-SXT) of human PC3 prostate cancer cells treated with 1, irradiated with blue light, and cryopreserved to maintain them in their native state, reveal that irradiation causes extensive and specific alterations to mitochondria, but not other cellular components. Such new insights into the effect of ¹O₂ generation during PDT using iridium photosensitisers on cells contribute to a detailed understanding of their cellular mode of action.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s00775-020-01761-8) contains supplementary material, which is available to authorized users.

Synthesis and Photodynamic Activity of Vitamin-Chlorin Conjugates at Nanomolar Concentrations against Prostate Cancer Cells

Phototoxicity response of synthesized vitamin-chlorin conjugates and their zinc and indium complexes was determined in the human PC-3 prostate cancer cell line, which was previously demonstrated to overexpress vitamin receptors on the cell surface. Pantothenic acid (Vit B5) and lipoic acid (or thioctic acid) were covalently linked to methyl pheophorbide (a chlorophyll derivative) and subsequently metallated with zinc and indium. Cell survival assay indicated that the vitamin-chlorin conjugates have better photodynamic activity against the PC-3 prostate cancer line at the nanomolar concentration range than the commercially available starting precursor methyl pheophorbide. Fluorescence and transmission electron microscopy studies indicated some formation of apoptotic cells and cytoplasmic vacuoles of photosensitized prostatic cells. Targeting vitamin receptors in prostatic cancer cells can be utilized to enhance specificity of photosensitizers for photodynamic therapy applications.

Polyphotosensitizer nanogels for GSH-responsive histone deacetylase inhibitors delivery and enhanced cancer photodynamic therapy

Photodynamic therapy (PDT) is one of the non-invasive and selective treatment methodologies for cancer. However, many highly efficient photosensitizers (PSs) are usually low physiological solubility, limited bioavailability and tending aggregation, impeding the effectiveness of PDT, as well as cancer resistance of PDT further reduce its therapeutic effect. Though some smart delivery systems have been developed, the problem of photosensitizer leakage/release has not been completely solved. Herein, we developed a smart therapeutic nanoplatform based on polyphotosensitizer nanogel as novel nanophotosensitizers and drug carriers. Moreover, by loading of histone deacetylase inhibitors (SAHA), it allows for enhanced synergistic therapy strategy of prostate cancer via inhibiting HIF-1α and VEGF pathways of cancer cells involved in PDT resistance. Our study presents the well-designed nanoplatform of nanogel-Ce6, which could serve as a photodynamic agent without Ce6 molecules release in the responsive environment, offering the potential to encapsulate diverse functional components for smart drug release and imaging-guided combination therapy in vitro and in vivo.

Metal-based photosensitizers for photodynamic therapy: the future of multimodal oncology?

Photodynamic therapy (PDT) is an approved medical technique to treat certain forms of cancer. It has been used to complement traditional anticancer modalities such as surgery, chemotherapy or radiotherapy, and in certain cases, to replace these treatments. One critical parameter of PDT is the photosensitizer (PS); historically, a purely organic macrocyclic tetrapyrrole-based structure. This short review surveys two recent clinical examples of metal complexes, namely TOOKAD®-Soluble and TLD-1433, which have ideal photophysical properties to act as PDT PSs. We highlight the important role played by the metal ions in the PS for PDT activity.

Light-Induced Therapies for Prostate Cancer Treatment

Prostate cancer (PC) is one of the most widespread tumors affecting the urinary system and the fifth-leading cause from cancer death in men worldwide. Despite PC mortality rates have been decreasing during the last years, most likely due to an intensification of early diagnosis, still more than 300,000 men die each year because of this disease. In this view, researchers in all countries are engaged in finding new ways to tackle PC, including the design and synthesis of novel molecular and macromolecular entities able to challenge different PC biological targets, while limiting the extent of unwanted side effects that significantly limit men's life quality. Among this field of research, photo-induced therapies, such as photodynamic and photothermal therapies (PDT and PTT), might represent an important advancement in PC treatment due to their extremely localized and controlled cytotoxic effect, as well as their low incidence of side effects and tumor resistance occurrence. Based on these considerations, this review aims to gather and discuss the last 5-years literature reports dealing with the synthesis and biological activity of molecular conjugates and nano-platforms for photo-induced therapies as co-adjuvant or combined therapeutic modalities for the treatment of localized PC.

Comparison of Cellular Death Pathways after mTHPC-mediated Photodynamic Therapy (PDT) in Five Human Cancer Cell Lines

One of the most promising photosensitizers (PS) used in photodynamic therapy (PDT) is the porphyrin derivative 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC, temoporfin), marketed in Europe under the trade name Foscan^®. A set of five human cancer cell lines from head and neck and other PDT-relevant tissues was used to investigate oxidative stress and underlying cell death mechanisms of mTHPC-mediated PDT in vitro. Cells were treated with mTHPC in equitoxic concentrations and illuminated with light doses of 1.8-7.0 J/cm² and harvested immediately, 6, 24, or 48 h post illumination for analyses. Our results confirm the induction of oxidative stress after mTHPC-based PDT by detecting a total loss of mitochondrial membrane potential (Δψ_m) and increased formation of ROS. However, lipid peroxidation (LPO) and loss of cell membrane integrity play only a minor role in cell death in most cell lines. Based on our results, apoptosis is the predominant death mechanism following mTHPC-mediated PDT. Autophagy can occur in parallel to apoptosis or the former can be dominant first, yet ultimately leading to autophagy-associated apoptosis. The death of the cells is in some cases accompanied by DNA fragmentation and a G₂/M phase arrest. In general, the overall phototoxic effects and the concentrations as well as the time to establish these effects varies between cell lines, suggesting that the cancer cells are not all dying by one defined mechanism, but rather succumb to an individual interplay of different cell death mechanisms. Besides the evaluation of the underlying cell death mechanisms, we focused on the comparison of results in a set of five identically treated cell lines in this study. Although cells were treated under equitoxic conditions and PDT acts via a rather unspecific ROS formation, very heterogeneous results were obtained with different cell lines. This study shows that general conclusions after PDT in vitro require testing on several cell lines to be reliable, which has too often been ignored in the past.

Photodynamic therapy by lysosomal-targeted drug delivery using talaporfin sodium incorporated into inactivated virus particles

Background

Photodynamic therapy (PDT), a minimally invasive cancer treatment involving the activation of photosensitizer by a specific wavelength of light, is considered to be a promising treatment option for drug-resistant prostate cancer. Hemagglutinating virus of Japan envelope (HVJ-E) has the potential to serve as a highly effective cancer therapy through selective drug delivery and enhancement of the anti-tumor immune response.

Objectives

To improve therapeutic efficacy and selective accumulation of photosensitizer into tumor cells, we developed a novel photosensitizer, Laserphyrin^®-HVJ-E (L-HVJ-E), by incorporating talaporfin sodium (Laserphyrin^®, Meiji Seika Pharma) into HVJ-E.

Materials and Methods

The therapeutic effect of PDT with Laserphyrin^® or L-HVJ-E was evaluated in the human prostate cancer cell line PC-3 in vitro. The subcellular localizations of Laserphyrin^® and L-HVJ-E were observed by confocal microscopy. Apoptosis or necrosis following PDT was detected by annexin V-fluorescein/propidium iodide double staining.

Results

The cytotoxic effect of Laserphyrin^®- and L-HVJ-E-mediated PDT were determined by evaluating cell survival rate and production of reactive oxygen species. The cytotoxicity of L-HVJ-E-mediated PDT was dependent on drug concentration and light dose. Laserphyrin^® and L-HVJ-E gradually entered cells as incubation time increased, and both agents tended to be distributed in lysosomes rather than mitochondria. Time and dose dependent increase in ROS production was observed, and induction of both apoptotic and necrotic cell death was confirmed.

Conclusions

Laserphyrin^® and L-HVJ-E were distributed mainly in lysosomes and induced cell death by both apoptosis and necrosis. Furthermore, L-HVJ-E-mediated PDT effectively killed cultured PC-3 cells and exerted higher photocytotoxicity than Laserphyrin^®-mediated PDT.

Photodynamic therapy for prostate cancer: a systematic review and meta-analysis

Purpose

Photodynamic therapy (PDT) is an emerging focal treatment modality for prostate cancer. However, the efficacy, safety, and functional outcomes of PDT are not clear. We performed a meta-analysis of available single-arm studies and control trials which used PDT for prostate cancer.

Materials and methods

We searched Pubmed, Embase, Ovid and the Cochrane library (until March,2018) for studies about PDT in patients with prostate cancer. The negative biopsy rate after PDT, PSA decreasing rate, pooled rate of functional outcome (IPSS or IIEF-5), and adverse events were analyzed.

Results

14 studies containing 654 patients were included. Nine of the 14 included studies had evaluated a negative biopsy rate after PDT. The pooled rate was 55.0% (95.0% CI: 0.44–0.66, I² = 85.7%). Twelve of the 14 included studies which evaluated PSA decreasing rate with the pooled rate of 35.0% (95.0% CI: 0.24–0.47, I² = 88.7%). Six of the included studies evaluated IPSS with decreasing rate of 29.1% (95.0 % CI: 2.7%–55.5%, I² = 96.9%). Five of the included studies evaluated IIEF-5 with decreasing rate of 14.9% (95.0% CI: 6.8%–23.0%, I² = 44.2%). The most common adverse events were haematuria (28.1%, 95.0% CI: 17.1%–39.2%, I² = 79.8%), erectile dysfunction (23.1%, 95.0% CI: 9.7%–36.5%, I² = 87.7%), and dysuria (18.6%, 95.0% CI: 12.1%–25.0 %, I² = 53.4 %).

Conclusions

The meta-analysis results shows that PDT for patients with prostate cancer can be considered as effective based on single-arm clinical trials. Meanwhile, this study reveals that there are not only low levels of side effect rates but also insignificant effect on both urinary and erectile function. However, more high-quality RCTs are needed to evaluate the comparative efficacy, safety, and functional outcomes of PDT for patients with prostate cancer.

Cyclodextrin-based delivery systems for cancer treatment

Cyclodextrins, one of safe excipients, are able to form host-guest complexes with fitted molecules given the unique nature imparted by their structure in result of a number of pharmaceutical applications. On the other hand, targeted or responsive materials are appealing therapeutic platforms for the development of next-generation precision medications. Meanwhile, cyclodextrin-based polymers or assemblies can condense DNA and RNA in result to be used as genetic therapeutic agents. Armed with a better understanding of various pharmaceutical mechanisms, especially for cancer treatment, researchers have made lots of works about cyclodextrin-based drug delivery systems in materials chemistry and pharmaceutical science. This Review highlights recent advances in cyclodextrin-based delivery systems for cancer treatment capable of targeting or responding to the physiological environment. Key design principles, challenges and future directions, including clinical translation, of cyclodextrin-based delivery systems are also discussed.

Measurement of Cyanine Dye Photobleaching in Photosensitizer Cyanine Dye Conjugates Could Help in Optimizing Light Dosimetry for Improved Photodynamic Therapy of Cancer

Photodynamic therapy (PDT) of cancer is dependent on three primary components: photosensitizer (PS), light and oxygen. Because these components are interdependent and vary during the dynamic process of PDT, assessing PDT efficacy may not be trivial. Therefore, it has become necessary to develop pre-treatment planning, on-line monitoring and dosimetry strategies during PDT, which become more critical for two or more chromophore systems, for example, PS-CD (Photosensitizer-Cyanine dye) conjugates developed in our laboratory for fluorescence-imaging and PDT of cancer. In this study, we observed a significant impact of variable light dosimetry; (i) high light fluence and fluence rate (light dose: 135 J/cm², fluence rate: 75 mW/cm²) and (ii) low light fluence and fluence rate (128 J/cm² and 14 mW/cm² and 128 J/cm² and 7 mW/cm²) in photobleaching of the individual chromophores of PS-CD conjugates and their long-term tumor response. The fluorescence at the near-infrared (NIR) region of the PS-NIR fluorophore conjugate was assessed intermittently via fluorescence imaging. The loss of fluorescence, photobleaching, caused by singlet oxygen from the PS was mapped continuously during PDT. The tumor responses (BALB/c mice bearing Colon26 tumors) were assessed after PDT by measuring tumor sizes daily. Our results showed distinctive photobleaching kinetics rates between the PS and CD. Interestingly, compared to higher light fluence, the tumors exposed at low light fluence showed reduced photobleaching and enhanced long-term PDT efficacy. The presence of NIR fluorophore in PS-CD conjugates provides an opportunity of fluorescence imaging and monitoring the photobleaching rate of the CD moiety for large and deeply seated tumors and assessing PDT tumor response in real-time.

Immune consequences induced by photodynamic therapy in non-melanoma skin cancers: a review

Photodynamic therapy (PDT) is widely used in dermatology to treat precancerous skin lesions and superficial non-melanoma skin cancers (NMSCs), including premalignant actinic keratosis, cutaneous squamous cell carcinoma in situ, and superficial basal cell carcinoma. The long-term cure rates of PDT range from 70 to 90% in NMSC patients, with excellent cosmetic results and good tolerance. However, the mechanism of action of PDT on tumors is complex. PDT not only kills tumor cells directly but also rapidly recruits immune cells to release inflammatory mediators to activate antitumor immunity. PDT-induced tumor death, also called immunogenic cell death, can trigger both innate and adaptive immune response, further enhancing the antitumor effect. For instance, inoculation of tumor cells killed via PDT to animals triggered a stronger antitumor immunity in vivo than tumor cell lysates produced by other treatments. More importantly, many immunotherapy regimens based on the immune effect of PDT have been developed and demonstrated to be a promising therapeutic method for cancer in pre-clinical trials. Therefore, increasing efforts have been undertaken to investigate the immune responses associated with PDT. In the present review, we first introduce the antitumor effect and the associated mechanisms of PDT in cancers. Then, we summarize studies on the immune responses induced by PDT in NMSCs. We also discuss the potential mechanisms underlying the process.

Proteomic analysis reveals that pheophorbide a-mediated photodynamic treatment inhibits prostate cancer growth by hampering GDP-GTP exchange of ras-family proteins

BACKGROUND

We previously reported that pheophorbide a (PhA), excited by 630 nm light, significantly inhibited the growth of prostate cancer cells. In this study, we employed whole-cell proteomics to investigate photodynamic treatment (PDT)-related proteins.

METHODS

Two-dimensional gel electrophoresis (2-DE) coupled with tandem mass spectrometry was employed to reveal the proteins involved in PhA-mediated PDT in LNCaP and PC-3 prostate cancer cells.

RESULTS

After PhA-PDT treatment, decreased expression of translationally-controlled tumor protein (TCTP) was found in both PC-3 and LNCaP whole-cell proteomes. In contrast, human rab GDP dissociation inhibitor (GDI) in LNCaP cells and ras-related homologs GDI in PC-3 cells were up-regulated.

CONCLUSIONS

GDP-GTP exchange is an underlying target of photodynamic treatment in prostate cancer cells.

Gendermetrics of cancer research: results from a global analysis on prostate cancer

BACKGROUND

The present study aims to elucidate the success concerning gender equality in cancer research in the last decade (from 2008 to 2017) with prostate cancer as the target parameter.

RESULTS

31.7% of all authorships and 36.3% of the first, 32.5% of the co- and 22.6% of the last authorships were held by women. The corresponding female-to-male odds ratio is 1.26 (CI: 1.22-1.30) for first, 1.15 (CI: 1.12-1.18) for co- and 0.59 (CI: 0.57-0.62) for last authorships. The annual growth rates are 0.6% overall and 0.9% for first, 0.2% for co-authorships, and 2.8% for last authorships. Women are slightly underrepresented at prestigious authorships compared to men. The female underrepresentation accentuates in articles with many authors that attract the highest citation rates. Multi-author articles with male key authors are more frequently cited. Men publish more articles compared to women (61.8% male authors are responsible for 68.3% of the authorships) and are overrepresented at productivity levels of more than 1 article per author. Major regional differences were found with best female odds in Sweden, Brazil, and Austria. The prognosis for the next decade forecasts a harmonization of authorship odds.

CONCLUSION

Prostate cancer research is characterized by a career dichotomy with few women in academic leadership positions and many female early career researchers. This career dichotomy has been narrowed in the last decade and will likely be further reduced in the future.

METHODS

On the basis of the Gendermetrics Platform, a total of 26,234 articles related to prostate cancer research were analyzed.