Photodynamic therapy and cell death pathways

Smart SPIONs for Multimodal Cancer Theranostics: A Review

Despite significant advancements in anticancer research, the performance statistics of current therapeutic regimens yield unsatisfactory outcomes. Issues such as high metastasis rates, drug resistance, limited efficacy, and severe side effects underscore the urgent need for safer and more effective strategies for tumor mitigation. One promising approach lies in the use of superparamagnetic iron oxide nanoparticles (SPIONs) for hybridized cancer therapy, leveraging their unique properties and functional versatility to enhance treatment efficacy and safety. They can serve as platforms for various therapeutic as well as diagnostic applications, enhancing imaging techniques such as magnetic resonance imaging. This paper presents an in-depth compilation of the application of nanoparticulate SPIONs amalgamates for multimodal cancer therapeutics. Physical phenomena such as light, heat, sound, and magnetism can be coupled to nanoparticulate delivery systems for developing targeted, precision medicine against cancer. Integration of noninvasive and effective platforms technologies such as photodynamic therapy, photothermal therapy, magnetic hyperthermia, and sonodynamic therapy hold great promise in counteracting the daunting challenges within cancer therapeutics.

"Effects of Redox Status on Immediate Hypericin-Mediated Photodynamic Therapy in Human Glioblastoma T98G Cell Line"

Glioblastoma Multiforme (GBM) is one of the most aggressive types of brain tumor. GBM can modulate glutathione (GSH) levels and regulate cellular redox state, which can explain its high resistance to chemotherapeutic agents. Photodynamic therapy (PDT) is a selective, nontoxic, and minimally invasive treatment approved for many types of cancer. PDT leads to cell death mainly by promoting the generation of reactive oxygen species (ROS). Thus, in the current study, PDT with the photosensitizer hypericin (Hyp), formulated in mixed 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/biotinylated-pluronic F127 (F127-B) liposomes, in combination with the GSH synthesis inhibitor buthionine sulfoximine (BSO) were tested against T98G cell line of human glioblastoma. The mixed liposome was effective in delivering Hyp to the cells, leading to a dose relationship between Hyp and ROS levels. BSO potentiated Hyp cell uptake, decreased GSH levels regardless of Hyp concentration, and intensified ROS generation for 1.00 and 5.00 μmol L-1 Hyp. Nonetheless, cell death was more pronounced in the groups not treated with BSO, indicating that reduced GSH levels are not a decisive factor in achieving the PDT effects of Hyp. In conclusion, the mixed DPPC/F127-B liposomes were effective as a delivery system for Hyp. However, the combination of BSO and Hyp was not capable of optimizing PDT against T98G cells.

Photodynamic Therapy: Past, Current, and Future

The Greek roots of the word "photodynamic" are as follows: "phos" (φω~ς) means "light" and "dynamis" (δύναμις) means "force" or "power". Photodynamic therapy (PDT) is an innovative treatment method based on the ability of photosensitizers to produce reactive oxygen species after the exposure to light that corresponds to an absorbance wavelength of the photosensitizer, either in the visible or near-infrared range. This process results in damage to pathological cancer cells, while minimizing the impact on healthy tissues. PDT is a promising direction in the treatment of many diseases, with particular emphasis on the fight against cancer and other diseases associated with excessive cell growth. The power of light contributed to the creation of phototherapy, whose history dates back to ancient times. It was then noticed that some substances exposed to the sun have a negative effect on the body, while others have a therapeutic effect. This work provides a detailed review of photodynamic therapy, from its origins to the present day. It is surprising how a seemingly simple beam of light can have such a powerful healing effect, which is used not only in dermatology, but also in oncology, surgery, microbiology, virology, and even dentistry. However, despite promising results, photodynamic therapy still faces many challenges. Moreover, photodynamic therapy requires further research and improvement.

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.

Recent breakthroughs in graphene quantum dot-enhanced sonodynamic and photodynamic therapy

Water-soluble graphene quantum dots (GQDs) have recently exhibited considerable potential for diverse biomedical applications owing to their exceptional optical and chemical properties. However, the pronounced heterogeneity in the composition, size, and morphology of GQDs poses challenges for a comprehensive understanding of the intricate correlation between their structural attributes and functional properties. This variability also introduces complexities in scaling the production processes and addressing safety considerations. Light and sound have firmly established their role in clinical applications as pivotal energy sources for minimally invasive therapeutic interventions. Given the limited penetration depth of light, photodynamic therapy (PDT) predominantly targets superficial conditions such as dermatological disorders, head and neck malignancies, ocular ailments, and early-stage esophageal cancer. Conversely, ultrasound-based sonodynamic therapy (SDT) capitalizes on its superior ability to propagate and focus ultrasound within biological tissues, enabling a diverse range of therapeutic applications, including the management of gliomas, breast cancer, hematological tumors, and modulation of the blood-brain barrier (BBB). Considering the advancements in theranostic and precision therapies, reevaluating these conventional energy sources and their associated sensitizers is imperative. This review introduces three prevalent treatment modalities that harness light and sound stimuli: PDT, SDT, and a synergistic approach that integrates PDT and SDT. This study delineated the therapeutic dynamics and contemporary designs of sensitizers tailored to these modalities. By exploring the historical context of the field and elucidating the latest design strategies, this review underscores the pivotal role of GQDs in propelling the evolution of PDT and SDT. This aspires to stimulate researchers to develop "multimodal" therapies integrating both light and sound stimuli.

Nano-phototherapy: Favorable prospects for cancer treatment

Nanotechnology-based phototherapies have drawn interest in the fight against cancer because of its noninvasiveness, high flexibility, and precision in terms of cancer targeting and drug delivery based on its surface properties and size. Phototherapy has made remarkable development in recent decades. Approaches to phototherapy, which utilize nanomaterials or nanotechnology have emerged to contribute to advances around nanotechnologies in medicine, particularly for cancers. A brief overviews of the development of photodynamic therapy as well as its mechanism in cancer treatment is provided. We emphasize the design of novel nanoparticles utilized in photodynamic therapy while summarizing the representative progress during the recent years. Finally, to forecast important future research in this area, we examine the viability and promise of photodynamic therapy systems based on nanoparticles in clinical anticancer treatment applications and briefly make mention of the elimination of all reactive metabolites pertaining to nano formulations inside living organisms providing insight into clinical mechanistic processes. Future developments and therapeutic prospects for photodynamic treatments are anticipated. Our viewpoints might encourage scientists to create more potent phototherapy-based cancer therapeutic modalities. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

The upregulation of immune checkpoints after photodynamic therapy reducing immune effect for treating breast cancer

The immune effect induced by photodynamic therapy (PDT) has a limited effect on breast tumor. This study hypothesized that suppressive immune checkpoints on T cells might upregulate after PDT, which may reduce the antitumor effect of PDT for treating breast tumor. This study explored the alteration of immune checkpoint for the first time. A bilateral subcutaneous transplanted breast tumor mice model was established, and right tumors imitated primary tumors, and left tumors imitated distant tumors. Primary tumors were treated with PDT mediated by hematoporphyrin derivatives (HpD-PDT). Costimulatory molecules (ICOS, OX40, and 4-1BB) and immune checkpoints (PD1, LAG-3, CTLA-4, TIM-3, TIGIT) on tumor infiltrating T cells after HpD-PDT were analyzed by flow cytometry. Antitumor and immune effects were also assessed after HpD-PDT combined with anti-PD1 and LAG-3 antibodies. Primary tumors were suppressed, but distant tumors could not be inhibited after HpD-PDT. The number of T cells was increased, but function did not enhance after HpD-PDT. Additionally, costimulatory molecules (ICOS, OX40, and 4-1BB) were not elevated, but the suppressive immune checkpoints on tumor infiltrating T cells were upregulated after HpD-PDT. Notably, PD1+ LAG-3+ CD4+ T and PD1+ LAG-3+ CD8+ T cells were significantly increased. When PD1 and LAG-3 blockade combined with HpD-PDT, both primary and distant tumors were significantly suppressed, and antitumor immune effects were significantly enhanced. HpD-PDT could upregulate the PD1+ LAG-3+ CD4+ T and PD1+ LAG-3+ CD8+ T cells. Dual blockade of PD1 and LAG-3 immune checkpoints can enhance the antitumor effect of HpD-PDT.

Applications of photodynamic therapy in extramammary Paget's disease

Extramammary Paget's disease (EMPD) is a rare form of adenocarcinoma usually found in apocrine gland-containing cutaneous regions. EMPD affects the vulvar area most commonly, followed by the perianal area, scrotum, penis, and axillary region. In its initial form, EMPD presents as an erythematous plaque with well-defined edges, fine scaling, excoriations, exulcerations, and lichenification. Generally, a definitive diagnosis can be made through histopathological analysis. Importantly, associated malignancies should be investigated prior to treatment initiation. Photodynamic therapy (PDT) is a modern, noninvasive treatment strategy for non-oncological diseases as well as various cancers. In recent years, PDT has been widely used to treat EMPD. This present article presents a discussion of the diagnosis and treatment of EMPD as well as the usefulness of PDT in its management.

8-Hydroxyquinoline-modified ruthenium(II) polypyridyl complexes for JMJD inhibition and photodynamic antitumor therapy

As an ideal scaffold for metal ion chelation, 8-hydroxyquinoline (8HQ) can chelate different metal ions, such as Fe²⁺, Cu²⁺, Zn²⁺, etc. Here, by integrating 8HQ with a ruthenium(II) polypyridyl moiety, two Ru(II)-8HQ complexes (Ru1 and Ru2), [Ru(N-N)₂L](PF₆)₂ (L = 2-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)quinolin-8-ol; N-N: 2,2'-bipyridine (bpy, in Ru1), 1,10-phenanthroline (phen, in Ru2)) were designed and synthesized. In both complexes, ligand L is an 8HQ derivative designed to chelate the cofactor Fe²⁺ of jumonji C domain-containing demethylase (JMJD). As expected, Ru1 and Ru2 could inhibit the activity of JMJD by chelating the key cofactor Fe²⁺ of JMJD, resulting in the upregulation of histone-methylation levels in human lung cancer (A549) cells, and the upregulation was more pronounced under light conditions. In addition, MTT data showed that Ru1 and Ru2 exhibited lower dark toxicity, and light irradiation could significantly enhance their antitumor activity. The marked photodynamic activities of Ru1 and Ru2 could induce the elevation of reactive oxygen species (ROS), depolarization of mitochondrial membrane potential (MMP), and activation of caspases. These mechanistic studies indicated that Ru1 and Ru2 could induce apoptosis through the combination of JMJD inhibitory and PDT activities, thereby achieving dual antitumor effects.

Recent Advances in Near Infrared Upconverting Nanomaterials for Targeted Photodynamic Therapy of Cancer

Photodynamic therapy (PDT) is a well-established treatment of cancer that uses the toxic reactive oxygen species, including singlet oxygen (1O2), generated by photosensitiser drugs following irradiation of a specific wavelength to destroy the cancerous cells and tumours. Visible light is commonly used as the excitation source in PDT, which is not ideal for cancer treatment due to its reduced tissue penetration, and thus inefficiency to treat deep-lying tumours. Additionally, these wavelengths exhibit elevated autofluorescence background from the biological tissues which hinders optical biomedical imaging. An alternative to UV-Vis irradiation is the use of near infrared (NIR) excitation for PDT. This can be achieved using upconverting nanoparticles (UCNPs) functionalised with photosensitiser (PS) drugs where UCNPs can be used as an indirect excitation source for the activation of PS drugs yielding to the production of singlet 1O2 following NIR excitation. The use of nanoparticles for PDT is also beneficial due to their tumour targeting capability, either passively via the enhanced permeability and retention (EPR) effect or actively via stimuli-responsive targeting and ligand-mediated targeting (ie. using recognition units that can bind specific receptors only present or overexpressed on tumour cells). Here, we review recent advances in NIR upconverting nanomaterials for PDT of cancer with a clear distinction between those reported nanoparticles that could potentially target the tumour due to accumulation via the EPR effect (passive targeting) and nanoparticle-based systems that contain targeting agents with the aim of actively target the tumour via a molecular recognition process.

Photodynamic Methylene Blue-Embedded Intragastric Satiety-Inducing Device to Treat Obesity

Bariatric surgery is the most effective treatment for weight recidivism, and endoscopic bariatric treatment has been developed for a similar effect without anatomical modification. An intragastric satiety-inducing device (ISD) is a minimally invasive approach to induce satiety by continuously pressing the stomach and stimulating ghrelin-producing cells. To enhance the therapeutic effects of ISD, photodynamic therapy (PDT) can be combined by generating singlet oxygen under laser irradiation. Methylene blue (MB), as a photosensitizer (PS), was coated on the ISD surface for singlet oxygen production to stimulate or destroy cells. Ghrelin-producing cells effectively inhibited ghrelin secretion and induced gastrointestinal satiety signals compared with the MB-uncoated device via PDT. Herein, MB-embedded ISDs were developed, and their photoresponsive abilities were demonstrated in the device itself and in vitro. PDT with an MB-embedded ISD was successfully performed in a porcine model, which had 2-fold reduced body weight gain (12% in PDT vs 24% in control) and 2-fold reduced ghrelin levels (21.2 pg/mL in PDT vs 45.1 pg/mL in control) at the first week postprocedure. The simple and unique operation extends the point of view in PDT and is expected to be a novel endoscopic bariatric therapy.

Smart nanocomposite assemblies for multimodal cancer theranostics

Despite great strides in anticancer research, performance statistics of current treatment modalities remain dismal, highlighting the need for safe, efficacious strategies for tumour mitigation. Non-invasive fusion technology platforms combining photodynamic, photothermal and hyperthermia therapies have emerged as alternate strategies with potential to meet many of the unmet clinical demands in the domain of cancer. These therapies make use of metallic and magnetic nanoparticles with light absorbing properties, which are manipulated to generate either reactive cytotoxic oxygen species or heat for tumour ablation. Combination therapies integrating light, heat and magnetism-mediated nanoplatforms with the conventional approaches of chemotherapy, radiotherapy and surgery are emerging as precision medicine for targeted interventions against cancer. This article aims to compile recent developments of advanced nanocomposite assemblies that integrate multimodal therapeutics for cancer treatment. Amalgamation of various effective, non-invasive technological platforms such as photodynamic therapy (PDT), photothermal therapy (PTT), magnetic hyperthermia (MHT), and chemodynamic therapy (CDT) have tremendous potential in presenting safe and efficacious solutions to the formidable challenges in cancer therapeutics.

Hyaluronic acid carrier-based photodynamic therapy for head and neck squamous cell carcinoma

PURPOSE

Conventional photosensitizers for photodynamic therapy (PDT) typically have wide tissue distribution and poor water solubility. A hyaluronic acid (HA) polymeric nanoparticle with specific lymphatic uptake and highly water solubility was developed to deliver pyropheophorbide-a (PPa) for locally advanced head and neck squamous cell carcinoma (HNSCC) treatment.

METHODS AND RESULTS

PPa was chemically conjugated to the HA polymeric nanoparticle via an adipic acid dihydrazide (ADH) linker. The conjugates were injected subcutaneously in a region near the tumor. Near-infrared (NIR) imaging was used to monitor distribution, and diode laser was used to activate PPa. The singlet oxygen generation efficiency of PPa was not affected by conjugation to HA nanoparticles at a PPa loading degree of 1.89 w.t.%. HA-ADH-PPa inhibited human HNSCC MDA-1986 cell growth only when photo-irradiation was applied. After HA-ADH-PPa treatment and radiation, NU/NU mice bearing human HNSCC MDA-1986 tumors showed reduced tumor growth and significantly enhanced survival time compared with an untreated group (p < 0.05).

CONCLUSIONS

These results demonstrate that HA-ADH-PPa could be useful for in vivo locoregional photodynamic therapy of HNSCC.

Fototerapia – metoda wykorzystywana w leczeniu przewlekłych schorzeń dermatologicznych

Wykorzystanie energii świetlnej w terapii schorzeń o różnej etiologii towarzyszy człowiekowi od czasów starożytnych. Elementem decydującym o powodzeniu terapii jest dobranie odpowiedniej długości promieniowania (terapia NB-UVB, BB-UVB i UVA1) lub wystąpienie interakcji między substancją światłoczułą skumulowaną w zmienionej chorobowo tkance a zastosowanym promieniowaniem (terapia PUVA oraz terapia fotodynamiczna). Metody terapeutyczne wykorzystujące energię świetlną są klasyfikowane na podstawie wykorzystywanego zakresu promieniowania. Obecnie wyróżnia się fototerapię UV, wykorzystującą promieniowanie UVA lub UVB oraz terapię fotodynamiczną (PDT; photodynamic therapy), podczas której stosowane jest promieniowanie o długości fali 350-700 nm.

Fototerapia UV wykorzystywana jest do leczenia schorzeń dermatologicznych, takich jak łuszczyca, bielactwo oraz atopowe zapalenie skóry, ze względu na jej działanie immunosupresyjne i antyproliferacyjne. Jest dostępna w postaci terapii PUVA polegającej na wykorzystaniu synergicznego działania promieniowania ultrafioletowego (UVA) oraz związków o działaniu światłouczulającym (8-metoksypsolaren, 5-metoksypsolaren). Ponadto wyróżniono monoterapię promieniowaniem ultrafioletowym A1 (UVA1), szerokozakresowym UVB (BB-UVB) i wąskozakresowym UVB (NB-UVB). Terapia fotodynamiczna obok konwencjonalnych metod leczenia jest nowoczesną i nieinwazyjną alternatywą wykorzystywaną zarówno w diagnostyce, jak i terapii chorób o różnej etiologii. W 90% przypadków PDT jest stosowana w schorzeniach dermatologicznych, takich jak trądzik pospolity czy łuszczyca. Selektywna aktywność cytotoksyczna wykazywana w kierunku złośliwych komórek nowotworowych powoduje, że terapia fotodynamiczna stosowana jest także z powodzeniem w leczeniu zmian onkologicznych. Duży postęp, przejawiający się zarówno w opracowywaniu innowacyjnych substancji światłoczułych, jak i nowych źródeł promieniowania, sprawia, iż zakres stosowalności terapii fotodynamicznej ciągle się poszerza.

W artykule przedstawiono obecnie dostępne formy fototerapii poprzez opis mechanizmu ich działania, zastosowania oraz możliwości powstania skutków niepożądanych.

Photodynamic Therapy-Current Limitations and Novel Approaches

Photodynamic therapy (PDT) mostly relies on the generation of singlet oxygen, via the excitation of a photosensitizer, so that target tumor cells can be destroyed. PDT can be applied in the settings of several malignant diseases. In fact, the earliest preclinical applications date back to 1900’s. Dougherty reported the treatment of skin tumors by PDT in 1978. Several further studies around 1980 demonstrated the effectiveness of PDT. Thus, the technique has attracted the attention of numerous researchers since then. Hematoporphyrin derivative received the FDA approval as a clinical application of PDT in 1995. We have indeed witnessed a considerable progress in the field over the last century. Given the fact that PDT has a favorable adverse event profile and can enhance anti-tumor immune responses as well as demonstrating minimally invasive characteristics, it is disappointing that PDT is not broadly utilized in the clinical setting for the treatment of malignant and/or non-malignant diseases. Several issues still hinder the development of PDT, such as those related with light, tissue oxygenation and inherent properties of the photosensitizers. Various photosensitizers have been designed/synthesized in order to overcome the limitations. In this Review, we provide a general overview of the mechanisms of action in terms of PDT in cancer, including the effects on immune system and vasculature as well as mechanisms related with tumor cell destruction. We will also briefly mention the application of PDT for non-malignant diseases. The current limitations of PDT utilization in cancer will be reviewed, since identifying problems associated with design/synthesis of photosensitizers as well as application of light and tissue oxygenation might pave the way for more effective PDT approaches. Furthermore, novel promising approaches to improve outcome in PDT such as selectivity, bioengineering, subcellular/organelle targeting, etc. will also be discussed in detail, since the potential of pioneering and exceptional approaches that aim to overcome the limitations and reveal the full potential of PDT in terms of clinical translation are undoubtedly exciting. A better understanding of novel concepts in the field (e.g. enhanced, two-stage, fractional PDT) will most likely prove to be very useful for pursuing and improving effective PDT strategies.

From molecules to nanovectors: Current state of the art and applications of photosensitizers in photodynamic therapy

Photodynamic therapy (PDT) is a concept based on a selective activation by light of drugs called photosensitizers (PS) leading to reactive oxygen species production responsible for cell destruction. Mechanisms of photodynamic reaction and cell photo-destruction following direct or indirect mechanisms will be presented as well as PS classification, from first generation molecules developed in the 1960 s to third generation vectorized PS with improved affinity for tumor cells. Many clinical applications in dermatology, ophthalmology, urology, gastroenterology, gynecology, neurosurgery and pneumology reported encouraging results in human tumor management. However, this interesting technique needs improvements that are currently investigated in the field of PS excitation by the design of new PS intended for two-photon excitation or for X-ray excitation. The former excitation technique is allowing better light penetration and preservation of healthy tissues while the latter is combining PDT and radiotherapy so that external light sources are no longer needed to generate the photodynamic effect. Nanotechnology can also improve the PS to reach the tumor cells by grafting addressing molecule and by increasing its aqueous solubility and consequently its bioavailability by encapsulation in synthetic or biogenic nanovector systems, ensuring good drug protection and targeting. Co-internalization of PS with magnetic nanoparticles in multifunctional vectors or stealth nanoplatforms allows a theranostic anticancer approach. Finally, a new category of inorganic PS will be presented with promising results on cancer cell destruction.

Photodynamic Therapy as a Potent Radiosensitizer in Head and Neck Squamous Cell Carcinoma

Simple Summary

Despite the advances in multimodality treatment strategies, more than 30% of patients with advanced head and neck squamous cell carcinoma (HNSCC) experience recurrence of the disease that is usually derived from the residual tumor. The goal of our study is to understand the molecular basis underlying radiotherapy resistance in advanced HNSCC and to identify a mechanism-based radiosensitizer. We found that the autophagic cell survival pathway is upregulated in therapy-resistant HNSCC. Photodynamic therapy (PDT) directed at the endoplasmic reticulum (ER)/mitochondria induces programmed cell death such as paraptosis and apoptosis in an autophagic adaptor p62-dependent manner, promoting radiotoxicity.

Abstract

Despite recent advances in therapeutic modalities such as radiochemotherapy, the long-term prognosis for patients with advanced head and neck squamous cell carcinoma (HNSCC), especially nonviral HNSCC, remains very poor, while survival of patients with human papillomavirus (HPV)-associated HNSCC is greatly improved after radiotherapy. The goal of this study is to develop a mechanism-based treatment protocol for high-risk patients with HPV-negative HNSCC. To achieve our goal, we have investigated molecular mechanisms underlying differential radiation sensitivity between HPV-positive and -negative HNSCC cells. Here, we found that autophagy is associated with radioresistance in HPV-negative HNSCC, whereas apoptosis is associated with radiation sensitive HPV-positive HNSCC. Interestingly, we found that photodynamic therapy (PDT) directed at the endoplasmic reticulum (ER)/mitochondria initially induces paraptosis followed by apoptosis. This led to a substantial increase in radiation responsiveness in HPV-negative HNSCC, while the same PDT treatment had a minimal effect on HPV-positive cells. Here, we provide evidence that the autophagic adaptor p62 mediates signal relay for the induction of apoptosis, promoting ionizing radiation (XRT)-induced cell death in HPV-negative HNSCC. This work proposes that ER/mitochondria-targeted PDT can serve as a radiosensitizer in intrinsically radioresistant HNSCC that exhibits an increased autophagic flux.

Inorganic Nanoparticles Applied for Active Targeted Photodynamic Therapy of Breast Cancer

Photodynamic therapy (PDT) is an alternative modality to conventional cancer treatment, whereby a specific wavelength of light is applied to a targeted tumor, which has either a photosensitizer or photochemotherapeutic agent localized within it. This light activates the photosensitizer in the presence of molecular oxygen to produce phototoxic species, which in turn obliterate cancer cells. The incidence rate of breast cancer (BC) is regularly growing among women, which are currently being treated with methods, such as chemotherapy, radiotherapy, and surgery. These conventional treatment methods are invasive and often produce unwanted side effects, whereas PDT is more specific and localized method of cancer treatment. The utilization of nanoparticles in PDT has shown great advantages compared to free photosensitizers in terms of solubility, early degradation, and biodistribution, as well as far more effective intercellular penetration and uptake in targeted cancer cells. This review gives an overview of the use of inorganic nanoparticles (NPs), including: gold, magnetic, carbon-based, ceramic, and up-conversion NPs, as well as quantum dots in PDT over the last 10 years (2009 to 2019), with a particular focus on the active targeting strategies for the PDT treatment of BC.

NIX initiates mitochondrial fragmentation via DRP1 to drive epidermal differentiation

The epidermis regenerates continually to maintain a protective barrier at the body’s surface composed of differentiating keratinocytes. Maturation of this stratified tissue requires that keratinocytes undergo wholesale organelle degradation upon reaching the outermost tissue layers to form compacted, anucleate cells. Through live imaging of organotypic cultures of human epidermis, we find that regulated breakdown of mitochondria is critical for epidermal development. Keratinocytes in the upper layers initiate mitochondrial fragmentation, depolarization, and acidification upon upregulating the mitochondrion-tethered autophagy receptor NIX. Depleting NIX compromises epidermal maturation and impairs mitochondrial elimination, whereas ectopic NIX expression accelerates keratinocyte differentiation and induces premature mitochondrial fragmentation via the guanosine triphosphatase (GTPase) DRP1. We further demonstrate that inhibiting DRP1 blocks NIX-mediated mitochondrial breakdown and disrupts epidermal development. Our findings establish mitochondrial degradation as a key step in terminal keratinocyte differentiation and define a pathway operating via the mitophagy receptor NIX in concert with DRP1 to drive epidermal morphogenesis.

Using live microscopy of human organotypic epidermis, Simpson et al. demonstrate how keratinocytes degrade their mitochondria in the upper tissue layers during their final stage of differentiation. By upregulating expression of the mitophagy receptor NIX, keratinocytes initiate DRP1- dependent mitochondrial fragmentation, a process critical for epidermal tissue maturation.

The role of FOS-mediated autophagy activation in the indocyanine green-based photodynamic therapy for treating melanoma

The morbidity and mortality of melanoma which accounts for 90% of cutaneous neoplasm-related deaths is growing over the last few decades. Common treatments for melanoma are limited to poor tissue selectivity, high toxicity and drug resistance. Photodynamic therapy (PDT) is an effective adjuvant therapy and could be a promising therapy for melanoma. Multiple mechanisms are involved in PDT2 and programmed cell death (PCD) which comprises of autophagy and apoptosis is likely to be a critical one. Whereas, the molecular mechanism and subsequent effect of PDT-induced autophagy in melanoma are still unclear. In this study, we first analyzed gene expression data in the TCGA3 and GEO4 databases to clarify that PDT-induced-autophagy improved the prognosis of melanoma. The expression of FOS which generally defined as an immediate-early gene (IEG) and related to cell autophagy was found significantly elevated after PDT. To further investigate whether FOS played a key role in PDT-induced-autophagy of melanoma, we first determined the optimum concentration of ICG solution for autophagy observation. Then, relative FOS expression was detected at mRNA and protein level and cell autophagy was observed by western blot and flow cytometry. We found that ICG-PDT treatment could significantly elevate FOS expression in SKCM5 B16 cells, and FOS promoted ICG-PDT-induced cell autophagy. To sum up, our data indicated that FOS was involved in ICG-PDT-induced-autophagy in melanoma and furthermore improved the prognosis of melanoma.

Molecular interaction and cellular studies on combination photodynamic therapy with rutoside for melanoma A375 cancer cells: an in vitro study

Background

Melanoma as a type of skin cancer, is associated with a high mortality rate. Therefore, early diagnosis and efficient surgical treatment of this disease is very important. Photodynamic therapy (PDT) involves the activation of a photosensitizer by light at specific wavelength that interacts with oxygen and creates singlet oxygen molecules or reactive oxygen species (ROS), which can lead to tumor cell death. Furthermore, one of the main approches in the prevention and treatment of various cancers is plant compounds application. Phenolic compounds are essential class of natural antioxidants, which play crucial biological roles such as anticancer effects. It was previously suggested that flavonoid such as rutoside could acts as pro-oxidant or antioxidant. Hence, in this study, we aimed to investigate the effect of rutoside on the combination therapy with methylene blue (MB) assisted by photodynamic treatment (PDT) using red light source (660 nm; power density: 30 mW/cm²) on A375 human melanoma cancer cells.

Methods

For this purpose, the A375 human melanoma cancer cell lines were treated by MB-PDT and rutoside. Clonogenic cell survival, MTT assay, and cell death mechanisms were also determined after performing the treatment. Subsequently, after the rutoside treatment and photodynamic therapy (PDT), cell cycle and intracellular reactive oxygen species (ROS) generation were measured.

Results

The obtained results showed that, MB-PDT and rutoside had better cytotoxic and antiprolifrative effects on A375 melanoma cancer cells compared to each free drug, whereas the cytotoxic effect on HDF human dermal fibroblast cell was not significant. MB-PDT and rutoside combination induced apoptosis and cell cycle arrest in the human melanoma cancer cell line. Intracellular ROS increased in A375 cancer cell line after the treatment with MB-PDT and rutoside.

Conclusion

The results suggest that, MB-PDT and rutoside could be considered as novel approaches as the combination treatment of melanoma cancer.

5-Aminolevulinic acid-mediated photodynamic therapy has effective antifungal activity against Sporothrix globosa in vitro

BACKGROUND

An alternative therapy for sporotrichosis is necessary to reduce the treatment time and raise clinical efficacy. The 5-Aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) is a promising platform with which to treat mycoses. However, despite the worldwide prevalence of Sporothrix globosa, a causative agent of sporotrichosis, the effect of ALA-PDT on this pathogen has not been validated.

OBJECTIVES

The aim of this study was to evaluate the effect of ALA-PDT on S globosa and the protection of melanin through an in vitro study. The mechanisms involved were also investigated.

METHODS

To estimate the survival rate of S globosa treated with ALA-PDT and the protection offered by melanin, the conidia and yeast cells of wild-type S globosa (Mel+), other clinical strains, tricyclazole-treated Mel+ and an albino mutant strain (Mel-) were incubated with and without ALA or irradiation. Reactive oxygen species generation by Mel+ conidia induced by ALA-PDT was assayed. SEM and TEM were conducted to obverse ultrastructural changes in the conidia. A comet assay was performed to evaluate DNA damage.

RESULTS

The survival rate of S globosa conidia and yeast cells significantly decreased following incubation with 1.19M ALA and 162 J/cm² irradiation in vitro. Melanin was not only capable of protecting the conidia against ALA-PDT, but also against ALA or irradiation alone. After induction by ALA-PDT, alterations in reactive oxygen species generation, DNA damage and ultrastructural changes were observed.

CONCLUSIONS

ALA-PDT inhibits the survival of S globosa conidia in vitro and therefore has potential for the treatment of sporotrichosis.

The role of autofluorescence, photodynamic diagnosis and Photodynamic therapy in malignant tumors of the duodenum

This article presents the current state of knowledge and a review of the literature in terms of the prevalence, etiopathogenesis, differential diagnosis, management, prognosis, and treatment of malignant tumors of the duodenum. The role of autofluorescence and photodynamic diagnosis as an emerging treatment method for rarely o ccurring duodenal malignant neoplasms .. We selected publications which can be found in databases such as The National Center for Biotechnology Information, U.S. National Library of Medicine (PubMed), The American Chemical Society, The American Association of Pharmaceutical Sciences and The American Society for Photobiology and The Canada Institute for Scientific and Technical Information.

Analysis of the short-term effect of photodynamic therapy on primary bronchial lung cancer

To analyze the short-term clinical effect of photodynamic therapy on bronchial lung cancer and provide relevant practical experience for its better application in clinical practice. Twenty patients with bronchial lung cancer diagnosed by pathology were treated with photodynamic therapy or interventional tumor reduction combined with photodynamic therapy. Follow-up at 3 months after treatment, the chest CT and bronchoscopy were reexamined. The lesions were observed under a microscope, and the pathological specimens of living tissues were stained with HE and TUNEL to evaluate the short-term clinical effect. The volume of the tumor in the trachea or bronchus was smaller than before and the obstruction improved after the PDT from the chest CT. We could conclude that after PDT, the tumor volume was reduced and the pathological tissue appeared necrotic, the surface was pale, and the blood vessels were fewer while compared with before, and less likely to bleed when touched from the results of the bronchoscopy. HE staining showed that before treatment, there were a large number of tumor cells, closely arranged and disordered, or agglomerated and distributed unevenly. The cell morphology was not clear and the sizes were various with large and deeply stained nucleus, and the intercellular substance was less. After treatment, the number of tumor cells decreased significantly compared with before and the arrangement was relatively loose and orderly. The cells were roughly the same size; the intercellular substance increased obviously and showed uniform staining. The nuclei morphology was incomplete and fragmented, and tumor cells were evenly distributed among the intercellular substance. TUNEL staining showed that the number of cells was large and the nucleus morphology was regular before treatment; the nuclear membrane was clear and only a small number of apoptotic cells could be seen. However, the number of cells decreased and arranged loosely after treatment, with evenly stained cytoplasm. The nuclear morphology was irregular and the nuclear membrane cannot be seen clearly. Apoptotic cells with typical characteristics such as karyopyknosis, karyorrhexis, and karyolysis were common. Photodynamic therapy for bronchial lung cancer can achieve a satisfactory short-term clinical treatment effect and improve the life quality of patients, but the long-term clinical effect remains to be further studied.

Photodynamic Therapy and Immunity: An Update

Dr. Thomas Dougherty and his Oncology Foundation of Buffalo were the first to support my (S.O.G.) research into the effects of photodynamic therapy (PDT) on the host immune system. The small grant I was awarded in 2002 launched my career as an independent researcher; at the time, there were few studies on the importance of the immune response on the efficacy of PDT and no studies demonstrating the ability of PDT to enhance antitumor immunity. Over the last decades, the interest in PDT as an enhancer of antitumor immunity and our understanding of the mechanisms by which PDT enhances antitumor immunity have dramatically increased. In this review article, we look back on the studies that laid the foundation for our understanding and provide an update on current advances and therapies that take advantage of PDT enhancement of immunity.

Flow-induced Shear Stress Confers Resistance to Carboplatin in an Adherent Three-Dimensional Model for Ovarian Cancer: A Role for EGFR-Targeted Photoimmunotherapy Informed by Physical Stress

A key reason for the persistently grim statistics associated with metastatic ovarian cancer is resistance to conventional agents, including platinum-based chemotherapies. A major source of treatment failure is the high degree of genetic and molecular heterogeneity, which results from significant underlying genomic instability, as well as stromal and physical cues in the microenvironment. Ovarian cancer commonly disseminates via transcoelomic routes to distant sites, which is associated with the frequent production of malignant ascites, as well as the poorest prognosis. In addition to providing a cell and protein-rich environment for cancer growth and progression, ascitic fluid also confers physical stress on tumors. An understudied area in ovarian cancer research is the impact of fluid shear stress on treatment failure. Here, we investigate the effect of fluid shear stress on response to platinum-based chemotherapy and the modulation of molecular pathways associated with aggressive disease in a perfusion model for adherent 3D ovarian cancer nodules. Resistance to carboplatin is observed under flow with a concomitant increase in the expression and activation of the epidermal growth factor receptor (EGFR) as well as downstream signaling members mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) and extracellular signal-regulated kinase (ERK). The uptake of platinum by the 3D ovarian cancer nodules was significantly higher in flow cultures compared to static cultures. A downregulation of phospho-focal adhesion kinase (p-FAK), vinculin, and phospho-paxillin was observed following carboplatin treatment in both flow and static cultures. Interestingly, low-dose anti-EGFR photoimmunotherapy (PIT), a targeted photochemical modality, was found to be equally effective in ovarian tumors grown under flow and static conditions. These findings highlight the need to further develop PIT-based combinations that target the EGFR, and sensitize ovarian cancers to chemotherapy in the context of flow-induced shear stress.

Differential in vitro sensitivity of oral precancerous and squamous cell carcinoma cell lines to 5-aminolevulinic acid-mediated photodynamic therapy

OBJECTIVES

The clinical effect of 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) may be correlated with the degree of dysplasia of cancer tissues, but much is still unknown regarding the differences in its effectiveness, especially in oral cancer and precancerous lesions. The aim of this study is to compare the effects of ALA-PDT on a human oral precancerous cell line (DOK) and an oral squamous cell carcinoma cell line (CAL-27).

METHODS

First, we explored the dose- and time-dependent responses of DOK and CAL-27 cells to ALA-PDT. DOK and CAL-27 cells were incubated with various concentrations of ALA (from 0.25 to 2 mM), followed by PDT using laser irradiation at 635 nm. The resulting photocytotoxicity was assessed in both cell lines using MTT assays. Further, apoptosis was assessed using flow cytometry, reactive oxygen species (ROS) generation was evaluated with 2,7-dichlorofluorescein diacetate (DCFH2-DA), and the response to treatment was examined via RT-qPCR and Western blotting to measure the mRNA and protein expression levels of matrix metallopeptidase 2 (MMP-2) and MMP-9.

RESULTS

ALA-PDT inhibited the proliferation of DOK and CAL-27 cells in a dose- and time-dependent manner. Dose-effect and inhibition-time relationships were also found. The rates of DOK and CAL-27 cell apoptosis when the ALA dose was 1 mM were 30.66 ± 3.10% and 75.40 ± 1.29%, respectively (P < 0.01). Following PDT, compared with DOK cells, the ROS level in CAL-27 cells was significantly increased and was correlated with an increase in the ALA concentration. Mechanistically, both the mRNA and protein expression levels of MMP-2 and MMP-9 were found to be regulated in both cell types after ALA-PDT.

CONCLUSION

ALA-PDT effectively killed DOK and CAL-27 cells in a dose- and time-dependent manner in vitro. However, under the same conditions, the susceptibilities of these cell lines to ALA-PDT were different. Further studies are necessary to confirm whether this difference is present in clinical oral cancer and precancerous lesions.

Nanocarriers in photodynamic therapy-in vitro and in vivo studies

Photodynamic therapy (PDT) is a minimally invasive technique which has proven to be successful in the treatment of several types of tumors. This relatively simple method exploits three inseparable elements: phototoxic compound (photosensitizer [PS]), light source, and oxygen. Upon irradiation by light with specified wavelength, PS generates reactive oxygen species, which starts the cascade of reactions leading to cell death. The positive therapeutic outcome of PDT may be limited due to several aspects, including low water solubility of PSs, hampering their effective administration and blood circulation, as well as low tumor specificity, inefficient cellular uptake and activation energies requiring prolonged illumination times. One of the promising approaches to overcome these obstacles involves the use of carrier systems modulating pharmacokinetics and pharmacodynamics of the PSs. In the present review, we summarized current in vitro and in vivo studies regarding the use of nanoparticles as potential delivery devices for PSs to enhance their cellular uptake and cytotoxic properties, and thus-the therapeutic outcome of PDT. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

A Combination of Visudyne and a Lipid-anchored Liposomal Formulation of Benzoporphyrin Derivative Enhances Photodynamic Therapy Efficacy in a 3D Model for Ovarian Cancer

A major objective in developing new treatment approaches for lethal tumors is to reduce toxicity to normal tissues while maintaining therapeutic efficacy. Photodynamic therapy (PDT) provides a mechanistically distinct approach to treat tumors without the systemic toxicity of chemotherapy drugs. PDT involves the light-based activation of a small molecule, a photosensitizer (PS), to generate reactive molecular species (RMS) that are toxic to target tissue. Depending on the PS localization, various cellular and subcellular components can be targeted, causing selective photodamage. It has been shown that targeted lysosomal photodamage followed by, or simultaneous with, mitochondrial photodamage using two different PS results in a considerable enhancement in PDT efficacy. Here, two liposomal formulations of benzoporphyrin derivative (BPD): (1) Visudyne (clinically approved) and (2) an in-house formulation entrapping a lipid conjugate of BPD are used in combination with direct PS localization to mitochondria, endoplasmic reticulum and lysosomes, enabling simultaneous photodamage to all three organelles using a single wavelength of light. Building on findings by our group, and others, this study demonstrates, for the first time in a 3D model for ovarian cancer, that BPD-mediated photodestruction of lysosomes and mitochondria/ER significantly enhances PDT efficacy at lower light doses than treatment with either PS formulation alone.

In-Vitro Use of 5-ALA for Photodynamic Therapy in Pediatric Brain Tumors

BACKGROUND

Light irradiation (635 nm) of cells containing protoporphyrin IX (PPIX) after 5- aminolevulinic acid (5-ALA) pretreatment causes cell death via different pathways including apoptosis and necrosis, as previously demonstrated for malignant glioma cells.

OBJECTIVE

To elucidate whether various malignant pediatric brain tumors, which have been shown to accumulate PPIX, would also be susceptible to photodynamic therapy (PDT).

METHODS

Medulloblastoma (DAOY, UW228), pNET (PFSK-1), and rhabdoid tumor (BT16) cell lines were incubated with 5-ALA in variable concentrations for 4 h. Consequently, cells were irradiated by 635 nm diode laser light. After 12 h, cell viability was measured by WST-1 testing and these results were compared to control cells incubated with 5-ALA without irradiation or irradiation only without prior incubation with 5-ALA.

RESULTS

We demonstrated significant cell death in malignant pediatric tumor cells after incubation with 5-ALA and laser irradiation in comparison to control groups. In all cell lines, we noticed significant cell death above a 5-ALA concentration of 50 μg/ml (P < .05). Neither 5-ALA incubation alone nor irradiation alone caused cell death. DAOY and PFSK cell lines were more susceptible than UW228 and BT16 cells.

CONCLUSION

We conclude that PDT causes cell death with higher PPIX concentrations after exposure to 5-ALA in vitro in accordance to similar studies with glioma cells. This indicates that PDT might be feasible for eliminating brain tumor cells in malignant pediatric brain tumors. Additionally, we noticed a dependency between fluorescence intensity and death rates.

Evaluation of cell damage induced by irradiated Zinc-Phthalocyanine-gold dendrimeric nanoparticles in a breast cancer cell line

BACKGROUND

Cancer is a non-communicable disease that occurs following a mutation in the genes which control cell growth. Breast cancer is the most diagnosed cancer among South African women and a major cause of cancer-related deaths worldwide. Photodynamic therapy (PDT) is an alternative cancer therapy that uses photochemotherapeutic agents, known as photosensitizers. Drug-delivery nanoparticles are commonly used in nanomedicine to enhance drug-therapeutic efficiency. This study evaluated the photodynamic effects following treatment with 0.3 μM multiple particles delivery complex (MPDC) and irradiated with a laser fluence of 10 J/cm2 using a 680 nm diode laser in a breast cancer cell line (MCF-7).

METHODS

Cell damage was assessed by inverted light microscopy for cell morphology; the Apoptox-Glo triple assay was used for cell viability, caspase activity and identification of cytodamage markers; flow cytometric analysis for cell death pathways and mitochondrial membrane potential; the enzyme linked immunosorbent assay (ELISA) for cytochrome C release; and real-time reverse transcriptase polymerase chain reaction (RT-PCR) array for gene expression.

RESULTS

Laser activated-MPDC induced a significant change in morphology of PDT-treated cells, with the appearance of apoptotic like morphological features. An increase in cytotoxicity, caspase activity, cell depolarization and cytochrome C release were identified in PDT-treated cells. Finally, the upregulation of BAX, BCL-2, CASP-2 and ULK-1 genes was observed.

CONCLUSION

The MPDC yielded a successful and stable hybrid agent with potent photodynamic abilities.

Photodynamic therapy - mechanisms, photosensitizers and combinations

Photodynamic therapy (PDT) is a modern and non-invasive form of therapy, used in the treatment of non-oncological diseases as well as cancers of various types and locations. It is based on the local or systemic application of a photosensitive compound - the photosensitizer, which is accumulated in pathological tissues. The photosensitizer molecules absorb the light of the appropriate wavelength, initiating the activation processes leading to the selective destruction of the inappropriate cells. The photocytotoxic reactions occur only within the pathological tissues, in the area of photosensitizer distribution, enabling selective destruction. Over the last decade, a significant acceleration in the development of nanotechnology has been observed. The combination of photosensitizers with nanomaterials can improve the photodynamic therapy efficiency and eliminate its side effects as well. The use of nanoparticles enables achievement a targeted method which is focused on specific receptors, and, as a result, increases the selectivity of the photodynamic therapy. The object of this review is the anticancer application of PDT, its advantages and possible modifications to potentiate its effects.

Photodynamic therapy in 3D cancer models and the utilisation of nanodelivery systems

Photodynamic therapy (PDT) is the subject of considerable research in experimental cancer models mainly for the treatment of solid cancerous tumours. Recent studies on the use of nanoparticles as photosensitiser carriers have demonstrated improved PDT efficacy in experimental cancer therapy. Experiments typically employ conventional monolayer cell culture but there is increasing interest in testing PDT using three dimensional (3D) cancer models. 3D cancer models can better mimic in vivo models than 2D cultures by for example enabling cancer cell interactions with a surrounding extracellular matrix which should enable the treatment to be optimised prior to in vivo studies. The aim of this review is to discuss recent research using PDT in different types of 3D cancer models, from spheroids to nano-fibrous scaffolds, using a range of photosensitisers on their own or incorporated in nanoparticles and nanodelivery systems.

Transferrin-Modified Nanoparticles for Photodynamic Therapy Enhance the Antitumor Efficacy of Hypocrellin A

Photodynamic therapy (PDT) has emerged as a potent novel therapeutic modality that induces cell death through light-induced activation of photosensitizer. But some photosensitizers have characteristics of poor water-solubility and non-specific tissue distribution. These characteristics become main obstacles of PDT. In this paper, we synthesized a targeting drug delivery system (TDDS) to improve the water-solubility of photosensitizer and enhance the ability of targeted TFR positive tumor cells. TDDS is a transferrin-modified Poly(D,L-Lactide-co-glycolide (PLGA) and carboxymethyl chitosan (CMC) nanoparticle loaded with a photosensitizer hypocrellin A (HA), named TF-HA-CMC-PLGA NPs. Morphology, size distribution, Fourier transform infrared (FT-IR) spectra, encapsulation efficiency, and loading capacity of TF-HA-CMC-PLGA NPs were characterized. In vitro TF-HA-CMC-PLGA NPs presented weak dark cytotoxicity and significant photo-cytotoxicity with strong reactive oxygen species (ROS) generation and apoptotic cancer cell death. In vivo photodynamic antitumor efficacy of TF-HA-CMC-PLGA NPs was investigated with an A549 (TFR positive) tumor-bearing model in male athymic nude mice. TF-HA-CMC-PLGA NPs caused tumor delay with a remarkable tumor inhibition rate of 63% for 15 days. Extensive cell apoptosis in tumor tissue and slight side effects in normal organs were observed. The results indicated that TDDS has great potential to enhance PDT therapeutic efficacy.

A novel 5-FU/rGO/Bce hybrid hydrogel shell on a tumor cell: one-step synthesis and synergistic chemo/photo-thermal/photodynamic effect

A novel drug-loaded inorganic nanoparticle–biomolecule hybrid hydrogel shell on tumor cells was firstly prepared.

Nitric oxide-mediated resistance to photodynamic therapy in a human breast tumor xenograft model: Improved outcome with NOS2 inhibitors

Many malignant tumors employ iNOS-derived NO to resist eradication by chemotherapeutic agents or ionizing radiation. In this study, we determined whether human breast carcinoma MDA-MB-231 cells in vitro and in vivo as tumor xenografts would exploit endogenous iNOS/NO to resist the cytotoxic effects of 5-aminolevulinic acid (ALA)-based photodynamic therapy (PDT). Broad band visible irradiation of ALA-treated cells resulted in a marked after-light upregulation of iNOS protein which persisted for at least 24 h. Apoptotic killing of ALA/light-challenged cells was significantly enhanced by iNOS inhibitors (1400W, GW274150) and a NO trap (cPTIO), implying that stress-induced iNOS/NO was acting cytoprotectively. We found that cells surviving the photostress proliferated and migrated more rapidly than controls in 1400W- and cPTIO-inhibitable fashion, indicating iNOS/NO involvement. Female SCID mice bearing MDA-MB-231 tumors were used for animal model experiments. ALA-PDT with a 633 nm light source caused a significant reduction in post-irradiation tumor growth relative to light-only controls, which was further reduced by administration of 1400W or GW274150, whereas 1400W had little or no effect on controls. Immunoblot analyses of tumor samples revealed a progressive post-PDT upregulation of iNOS, which reached >5-times the control level after six days. Correspondingly, the nitrite/nitrate level in post-PDT tumor samples was substantially higher than that in controls. In addition, a 1400W-inhibitable upregulation of pro-survival/progression effector proteins such as Bcl-xL, Survivin, and S100A4 was observed after in vitro and in vivo ALA-PDT. This is the first known study to demonstrate iNOS/NO-induced resistance to PDT in an in vivo human tumor model.

Effects of HSP27 downregulation on PDT resistance through PDT-induced autophagy in head and neck cancer cells

We previously reported that photodynamic therapy (PDT) induces cell death in head and neck cancer through both autophagy and apoptosis. Regulation of cell death by autophagy and apoptosis is important to enhance the effects of PDT. Autophagy maintains a balance between cell death and PDT resistance. Downregulation of heat shock protein 27 (HSP27) induces PDT resistance in head and neck cancer cells. Furthermore, HSP70 regulates apoptosis during oxidative stress. However, the role of HSPs in PDT-induced cell death through autophagy and apoptosis is unclear. Therefore, in the present study, we investigated the effects of HSP27 and HSP70 on PDT-induced cell death of oral cancer cells through autophagy and apoptosis. Cancer cells were treated with hematoporphyrin at varying doses, followed by irradiation at 635 nm with an energy density of 5 mW/cm2. We determined the changes in HSP expression by determining the levels of PARP-1 and LC3II in PDT-resistant cells. Furthermore, we assessed cell death signaling after downregulating HSPs by transfecting specific siRNAs. We observed that PDT decreased HSP27 expression but increased HSP70 expression in the head and neck cancer cells. Treatment of cells with LC3II and PARP-1 inhibitors resulted in upregulation of HSP70 and HSP27 expression, respectively. Downregulation of HSP27 and HSP70 induced cell death and PDT resistance through autophagy and apoptosis. Moreover, downregulation of HSP27 in PDT-resistant cells resulted in enhanced survival. These results indicate that the regulation of HSP27 and HSP70 plays a principal role in increasing the effects of PDT by inducing autophagic and apoptotic cell death.

Photodynamic therapy as an effective therapeutic approach in MAME models of inflammatory breast cancer

Photodynamic therapy (PDT) is a minimally invasive, FDA-approved therapy for treatment of endobronchial and esophageal cancers that are accessible to light. Inflammatory breast cancer (IBC) is an aggressive and highly metastatic form of breast cancer that spreads to dermal lymphatics, a site that would be accessible to light. IBC patients have a relatively poor survival rate due to lack of targeted therapies. The use of PDT is underexplored for breast cancers but has been proposed for treatment of subtypes for which a targeted therapy is unavailable. We optimized and used a 3D mammary architecture and microenvironment engineering (MAME) model of IBC to examine the effects of PDT using two treatment protocols. The first protocol used benzoporphyrin derivative monoacid A (BPD) activated at doses ranging from 45 to 540 mJ/cm(2). The second PDT protocol used two photosensitizers: mono-L-aspartyl chlorin e6 (NPe6) and BPD that were sequentially activated. Photokilling by PDT was assessed by live-dead assays. Using a MAME model of IBC, we have shown a significant dose-response in photokilling by BPD-PDT. Sequential activation of NPe6 followed by BPD is more effective in photokilling of tumor cells than BPD alone. Sequential activation at light doses of 45 mJ/cm(2) for each agent resulted in >90 % cell death, a response only achieved by BPD-PDT at a dose of 360 mJ/cm(2). Our data also show that effects of PDT on a volumetric measurement of 3D MAME structures reflect efficacy of PDT treatment. Our study is the first to demonstrate the potential of PDT for treating IBC.

Photodynamic therapy: a review and its prospective role in the management of oral potentially malignant disorders

With the unreliability of epithelial dysplasia as a predictor to determine the risk of future malignant development, subjectivity associated in evaluating dysplasia by pathologists and paucity of biomarkers that could accurately predict the progression risks in oral potentially malignant disorders (PMDs), eradication of the lesions appears to be the most desirable approach to minimize the risk of invasive cancer formation. Interventions, such as surgery and chemoprevention, have not shown promising long-term results in the treatment of these lesions, and lack of guidelines and general consensus on their management has incited much anxiety and doubts in both patients and community clinicians. Topical photodynamic therapy (PDT) is a minimally invasive and minimally toxic technique that in recent years has shown great promise in the management of PMDs. In this review, we describe the historical developments in the field of PDT, its basic mechanisms, as well as related clinical studies, and its challenges in the management of oral PMDs. Based on its high efficacy and low side effects, its high patient acceptance/compliance, the simplicity of the procedure and its minimal pretreatment preparation, topical PDT is believed to have potential to play an important role in the management of PMDs, especially of the low-grade dysplasia.

Phthalocyanine derivatives possessing 2-(morpholin-4-yl)ethoxy groups as potential agents for photodynamic therapy

Three 2-(morpholin-4-yl)ethoxy substituted phthalocyanines were synthesized and characterized. Phthalocyanine derivatives revealed moderate to high quantum yields of singlet oxygen production depending on the solvent applied (e.g., in DMF ranging from 0.25 to 0.53). Their photosensitizing potential for photodynamic therapy was investigated in an in vitro model using cancer cell lines. Biological test results were found particularly encouraging for the zinc(II) phthalocyanine derivative possessing two 2-(morpholin-4-yl)ethoxy substituents in nonperipheral positions. Cells irradiated for 20 min at 2 mW/cm(2) revealed the lowest IC50 value at 0.25 μM for prostate cell line (PC3), whereas 1.47 μM was observed for human malignant melanoma (A375) cells. The cytotoxic activity in nonirradiated cells of novel phthalocyanine was found to be very low. Moreover, the cellular uptake, localization, cell cycle, apoptosis through an ELISA assay, and immunochemistry method were investigated in LNCaP cells. Our results showed that the tested photosensitizer possesses very interesting biological activity, depending on experimental conditions.

Targeting mitochondria by Zn(II)N-alkylpyridylporphyrins: the impact of compound sub-mitochondrial partition on cell respiration and overall photodynamic efficacy

Mitochondria play a key role in aerobic ATP production and redox control. They harness crucial metabolic pathways and control cell death mechanisms, properties that make these organelles essential for survival of most eukaryotic cells. Cancer cells have altered cell death pathways and typically show a shift towards anaerobic glycolysis for energy production, factors which point to mitochondria as potential culprits in cancer development. Targeting mitochondria is an attractive approach to tumor control, but design of pharmaceutical agents based on rational approaches is still not well established. The aim of this study was to investigate which structural features of specially designed Zn(II)N-alkylpyridylporphyrins would direct them to mitochondria and to particular mitochondrial targets. Since Zn(II)N-alkylpyridylporphyrins can act as highly efficient photosensitizers, their localization can be confirmed by photodamage to particular mitochondrial components. Using cultured LS174T adenocarcinoma cells, we found that subcellular distribution of Zn-porphyrins is directed by the nature of the substituents attached to the meso pyridyl nitrogens at the porphyrin ring. Increasing the length of the aliphatic chain from one carbon (methyl) to six carbons (hexyl) increased mitochondrial uptake of the compounds. Such modifications also affected sub-mitochondrial distribution of the Zn-porphyrins. The amphiphilic hexyl derivative (ZnTnHex-2-PyP) localized in the vicinity of cytochrome c oxidase complex, causing its inactivation during illumination. Photoinactivation of critical cellular targets explains the superior efficiency of the hexyl derivative in causing mitochondrial photodamage, and suppressing cellular respiration and survival. Design of potent photosensitizers and redox-active scavengers of free radicals should take into consideration not only selective organelle uptake and localization, but also selective targeting of critical macromolecular structures.

St John's Wort (Hypericum perforatum L.) photomedicine: hypericin-photodynamic therapy induces metastatic melanoma cell death

Hypericin, an extract from St John's Wort (Hypericum perforatum L.), is a promising photosensitizer in the context of clinical photodynamic therapy due to its excellent photosensitizing properties and tumoritropic characteristics. Hypericin-PDT induced cytotoxicity elicits tumor cell death by various mechanisms including apoptosis, necrosis and autophagy-related cell death. However, limited reports on the efficacy of this photomedicine for the treatment of melanoma have been published. Melanoma is a highly aggressive tumor due to its metastasizing potential and resistance to conventional cancer therapies. The aim of this study was to investigate the response mechanisms of melanoma cells to hypericin-PDT in an in vitro tissue culture model. Hypericin was taken up by all melanoma cells and partially co-localized to the endoplasmic reticulum, mitochondria, lysosomes and melanosomes, but not the nucleus. Light activation of hypericin induced a rapid, extensive modification of the tubular mitochondrial network into a beaded appearance, loss of structural details of the endoplasmic reticulum and concomitant loss of hypericin co-localization. Surprisingly the opposite was found for lysosomal-related organelles, suggesting that the melanoma cells may be using these intracellular organelles for hypericin-PDT resistance. In line with this speculation we found an increase in cellular granularity, suggesting an increase in pigmentation levels in response to hypericin-PDT. Pigmentation in melanoma is related to a melanocyte-specific organelle, the melanosome, which has recently been implicated in drug trapping, chemotherapy and hypericin-PDT resistance. However, hypericin-PDT was effective in killing both unpigmented (A375 and 501mel) and pigmented (UCT Mel-1) melanoma cells by specific mechanisms involving the externalization of phosphatidylserines, cell shrinkage and loss of cell membrane integrity. In addition, this treatment resulted in extrinsic (A375) and intrinsic (UCT Mel-1) caspase-dependent apoptotic modes of cell death, as well as a caspase-independent apoptotic mode that did not involve apoptosis-inducing factor (501 mel). Further research is needed to shed more light on these mechanisms.

Enhanced efficacy of photodynamic therapy via a sequential targeting protocol

This study was designed to examine determinants of the discovery that low-dose lysosomal photodamage (lyso-PDT) could potentiate the efficacy of subsequent low-dose mitochondrial photodamage (mito-PDT). The chlorin NPe6 and the benzoporphyrin derivative (BPD) were used to separately target lysosomes and mitochondria, respectively, in murine hepatoma cells. Lyso-PDT (LD(5) conditions) followed by mito-PDT (LD(15) conditions) enhanced the loss of the mitochondrial membrane potential, activation of procaspases-3/7 and photokilling. Reversing the sequence was less effective. The optimal sequence did not enhance reactive oxygen species formation above that obtained with low-dose mito-PDT. In contrast, alkalinization of lysosomes with bafilomycin also enhanced low-dose mito-PDT photokilling, but via a different pathway. This involves redistribution of iron from lysosomes to mitochondria leading to enhanced hydroxyl radical formation, effects not observed after the sequential procedure. Moreover, Ru360, an inhibitor of mitochondrial calcium and iron uptake, partially suppressed the ability of bafilomycin to enhance mito-PDT photokilling without affecting the enhanced efficacy of the sequential protocol. We conclude that sequential PDT protocol promotes PDT efficacy by a process not involving iron translocation, but via promotion of the pro-apoptotic signal that derives from mitochondrial photodamage.

Induced cell death pathway post photodynamic therapy using a metallophthalocyanine photosensitizer in breast cancer cells

OBJECTIVE

Zinc phthalocyanine (ZnPcSmix) was used as the photosensitizer (PS) in this study to investigate the cell death patterns as a result of photodynamic therapy (PDT) in a breast cancer cell line (MCF-7) in vitro using a 680 nm diode laser at a fluence of 5 J/cm(2).

BACKGROUND

PDT is a noninvasive form of cancer therapy, successfully applied for the treatment of various cancer types.

METHODS

Flow cytometry using Annexin V-fluorescein isothiocyanate (FITC), a cell death immunosorbent assay (ELISA), and gene expression analysis following ZnPcSmix mediated PDT were performed to determine the induced cell death pathways.

RESULTS

The apoptotic cells abounded after the treatment, nuclear fragmentation was seen as oligonucleosomal degradation and increased expression of the B-cell lymphoma 2 (Bcl-2), DNA fragmentation factor alpha (DFFA1), and caspase 2 (CASP2) genes, indicated that apoptosis is the main induced mode of cell death.

CONCLUSIONS

ZnPcSmix mediated PDT led to an apoptotic cell death pathway and the PS used showed its ability to stimulate and initiate programmed cell death.