A basic study on hypericin-PDT in vitro

Photosensitizers for Photodynamic Therapy of Brain Cancers-A Review

On average, there are about 300,000 new cases of brain cancer each year. Studies have shown that brain and central nervous system tumors are among the top ten causes of death. Due to the extent of this problem and the percentage of patients suffering from brain tumors, innovative therapeutic treatment methods are constantly being sought. One such innovative therapeutic method is photodynamic therapy (PDT). Photodynamic therapy is an alternative and unique technique widely used in dermatology and other fields of medicine for the treatment of oncological and nononcological lesions. Photodynamic therapy consists of the destruction of cancer cells and inducing inflammatory changes by using laser light of a specific wavelength in combination with the application of a photosensitizer. The most commonly used photosensitizers include 5-aminolevulinic acid for the enzymatic generation of protoporphyrin IX, Temoporfin-THPC, Photofrin, Hypericin and Talaporfin. This paper reviews the photosensitizers commonly used in photodynamic therapy for brain tumors. An overview of all three generations of photosensitizers is presented. Along with an indication of the limitations of the treatment of brain tumors, intraoperative photodynamic therapy and its possibilities are described as an alternative therapeutic method.

Multifunctional Nanoparticles as High-Efficient Targeted Hypericin System for Theranostic Melanoma

Biotin, spermine, and folic acid were covalently linked to the F127 copolymer to obtain a new drug delivery system designed for HY-loaded PDT treatment against B₁₆F₁₀ cells. Chemical structures and binders quantification were performed by spectroscopy and spectrophotometric techniques (¹NMR, HABA/Avidin reagent, fluorescamine assay). Critical micelle concentration, critical micelle temperature, size, polydispersity, and zeta potential indicate the hydrophobicity of the binders can influence the physicochemical parameters. Spermine-modified micelles showed fewer changes in their physical and chemical parameters than the F127 micelles without modification. Furthermore, zeta potential measurements suggest an increase in the physical stability of these carrier systems. The phototherapeutic potential was demonstrated using hypericin-loaded formulation against B₁₆F₁₀ cells, which shows that the combination of the binders on F127 copolymer micelles enhances the photosensitizer uptake and potentializes the photodynamic activity.

Accumulation and penetration behavior of hypericin in glioma tumor spheroids studied by fluorescence microscopy and confocal fluorescence lifetime imaging microscopy

Glioblastoma WHO IV belongs to a group of brain tumors that are still incurable. A promising treatment approach applies photodynamic therapy (PDT) with hypericin as a photosensitizer. To generate a comprehensive understanding of the photosensitizer-tumor interactions, the first part of our study is focused on investigating the distribution and penetration behavior of hypericin in glioma cell spheroids by fluorescence microscopy. In the second part, fluorescence lifetime imaging microscopy (FLIM) was used to correlate fluorescence lifetime (FLT) changes of hypericin to environmental effects inside the spheroids. In this context, 3D tumor spheroids are an excellent model system since they consider 3D cell-cell interactions and the extracellular matrix is similar to tumors in vivo. Our analytical approach considers hypericin as probe molecule for FLIM and as photosensitizer for PDT at the same time, making it possible to directly draw conclusions of the state and location of the drug in a biological system. The knowledge of both state and location of hypericin makes a fundamental understanding of the impact of hypericin PDT in brain tumors possible. Following different incubation conditions, the hypericin distribution in peripheral and central cryosections of the spheroids were analyzed. Both fluorescence microscopy and FLIM revealed a hypericin gradient towards the spheroid core for short incubation periods or small concentrations. On the other hand, a homogeneous hypericin distribution is observed for long incubation times and high concentrations. Especially, the observed FLT change is crucial for the PDT efficiency, since the triplet yield, and hence the O₂ activation, is directly proportional to the FLT. Based on the FLT increase inside spheroids, an incubation time > 30 min is required to achieve most suitable conditions for an effective PDT.

Antimicrobial photodynamic therapy (aPDT) for biofilm treatments. Possible synergy between aPDT and pulsed electric fields

Currently, microbial biofilms have been the cause of a wide variety of infections in the human body, reaching 80% of all bacterial and fungal infections. The biofilms present specific properties that increase the resistance to antimicrobial treatments. Thus, the development of new approaches is urgent, and antimicrobial photodynamic therapy (aPDT) has been shown as a promising candidate. aPDT involves a synergic association of a photosensitizer (PS), molecular oxygen and visible light, producing highly reactive oxygen species (ROS) that cause the oxidation of several cellular components. This therapy attacks many components of the biofilm, including proteins, lipids, and nucleic acids present within the biofilm matrix; causing inhibition even in the cells that are inside the extracellular polymeric substance (EPS). Recent advances in designing new PSs to increase the production of ROS and the combination of aPDT with other therapies, especially pulsed electric fields (PEF), have contributed to enhanced biofilm inhibition. The PEF has proven to have antimicrobial effect once it is known that extensive chemical reactions occur when electric fields are applied. This type of treatment kills microorganisms not only due to membrane rupture but also due to the formation of reactive compounds including free oxygen, hydrogen, hydroxyl and hydroperoxyl radicals. So, this review aims to show the progress of aPDT and PEF against the biofilms, suggesting that the association of both methods can potentiate their effects and overcome biofilm infections.

The Effects of Photosensitizing Dyes Fagopyrin and Hypericin on Planktonic Growth and Multicellular Life in Budding Yeast

Naphthodianthrones such as fagopyrin and hypericin found mainly in buckwheat (Fagopyrum spp.) and St. John’s wort (SJW) (Hypericum perforatum L.) are natural photosensitizers inside the cell. The effect of photosensitizers was studied under dark conditions on growth, morphogenesis and induction of death in Saccharomyces cerevisiae. Fagopyrin and hypericin induced a biphasic and triphasic dose response in cellular growth, respectively, over a 10-fold concentration change. In fagopyrin-treated cells, disruptions in the normal cell cycle progression were evident by microscopy. DAPI staining revealed several cells that underwent premature mitosis without budding, a striking morphological abnormality. Flow Cytometric (FC) analysis using a concentration of 100 µM showed reduced cell viability by 41% in fagopyrin-treated cells and by 15% in hypericin-treated cells. FC revealed the development of a secondary population of G1 cells in photosensitizer-treated cultures characterized by small size and dense structures. Further, we show that fagopyrin and the closely related hypericin altered the shape and the associated fluorescence of biofilm-like structures. Colonies grown on solid medium containing photosensitizer had restricted growth, while cell-to-cell adherence within the colony was also affected. In conclusion, the photosensitizers under dark conditions affected culture growth, caused toxicity, and disrupted multicellular growth, albeit with different efficiencies.

Restoring the Immunity in the Tumor Microenvironment: Insights into Immunogenic Cell Death in Onco-Therapies

Immunogenic cell death (ICD) elicited by cancer therapy reshapes the tumor immune microenvironment. A long-term adaptative immune response can be initiated by modulating cell death by therapeutic approaches. Here, the major hallmarks of ICD, endoplasmic reticulum (ER) stress, and damage-associated molecular patterns (DAMPs) are correlated with ICD inducers used in clinical practice to enhance antitumoral activity by suppressing tumor immune evasion. Approaches to monitoring the ICD triggered by antitumoral therapeutics in the tumor microenvironment (TME) and novel perspective in this immune system strategy are also reviewed to give an overview of the relevance of ICD in cancer treatment.

Hypericin in photobiological assays: An overview

Hypericin is considered a potent photosensitizer for use in antitumor and antimicrobial photodynamic therapy (PDT). This review presents the primary biological results obtained with hypericin in photodynamic therapy applications, such as photodynamic cancer treatment, photoinactivation of microorganisms (PDI), tissue scarring, and photo diagnosis. We present a compilation of in vitro results that have been published thus far; for these studies, we highlight the hypericin concentration, light dose, and other experimental conditions to evaluate the efficiency of photodynamic treatment like cell death, cell viability, or cell proliferation. The results indicate that different hypericin phototoxicity levels can be observed according to the specific light dose and concentration. Furthermore, it was shown that cellular localization and cell death mechanisms (apoptosis and necrosis) are dependent on the cell type.

Hypericin-mediated photodynamic therapy inhibits growth of colorectal cancer cells via inducing S phase cell cycle arrest and apoptosis

Colorectal cancer (CRC) is one type of cancer with high morbidity and mortality worldwide. Photodynamic therapy (PDT), a promising new therapeutic approach for cancer, induces tumor damage through photosensitizer-mediated oxidative cytotoxicity. Hypericin is a powerful photosensitizer with pronounced tumor-localizing properties. In this study, we investigated the phototoxic effects of hypericin-mediated PDT (HYP-PDT) in HCT116 and SW620 cells. We validated that HYP-PDT inhibited cell proliferation, triggered intracellular reactive oxygen species generation, induced S phase cell cycle arrest and apoptosis of HCT116 and SW620 cells. Mechanistically, the results of western blot showed that HYP-PDT downregulated CDK2 expression through decreasing the CDC25A protein, which resulted in the decrease of CDK2/Cyclin A complex. Additionally, HYP-PDT induced DNA damage as evidenced by ATM activation and upregulation of p-H2AX. Further investigation showed that HYP-PDT significantly increased Bax expression and decreased Bcl-2 expression, and then, upregulated the expression of cleaved caspase-9, cleaved caspase-3 and cleaved PARP, thereby inducing apoptosis in HCT116 and SW620 cells. In conclusion, our results indicated that the CDC25A/CDK2/Cyclin A pathway and the mitochondrial apoptosis pathway were involved in HYP-PDT induced S phase cell cycle arrest and apoptosis in colorectal cancer cells, which shows HYP could be a probable candidate used for treating colorectal cancer.

Hypericin-mediated photodynamic therapy for the treatment of cancer: a review

OBJECTIVES

Hypericin is a polycyclic aromatic naphthodianthrone that occurs naturally. It is also an active ingredient in some species of the genus Hypericum. Emerging evidence suggests that hypericin has attracted great attention as a potential anticancer drug and exhibits remarkable antiproliferative effect upon irradiation on various tumour cells. This paper aims to summarise the anticancer effect and molecular mechanisms modulated by hypericin-medicated photodynamic therapy and its potential role in the cancer treatment.

KEY FINDINGS

Hypericin-medicated photodynamic therapy could inhibit the proliferation of various tumour cells including bladder, colon, breast, cervical, glioma, leukaemia, hepatic, melanoma, lymphoma and lung cancers. The effect is primarily mediated by p38 mitogen-activated protein kinase (MAPK), JNK, PI3K, CCAAT-enhancer-binding protein homologous protein (CHOP)/TRIB3/Akt/mTOR, TRAIL/TRAIL-receptor, c-Met and Ephrin-Eph, the mitochondria and extrinsic signalling pathways. Furthermore, hypericin-medicated photodynamic therapy in conjunction with chemotherapeutic agents or targeted therapies is more effective in inhibiting the growth of tumour cells.

SUMMARY

During the past few decades, the anticancer properties of photoactivated hypericin have been extensively investigated. Hypericin-medicated photodynamic therapy can modulate a variety of proteins and genes and exhibit a great potential to be used as a therapeutic agent for various types of cancer.

Selective photodynamic effects on cervical cancer cells provided by P123 Pluronic®-based nanoparticles modulating hypericin delivery

At present, cervical cancer is the fourth leading cause of cancer among women worldwide with no effective treatment options. In this study we aimed to evaluate the efficacy of hypericin (HYP) encapsulated on Pluronic® P123 (HYP/P123) photodynamic therapy (PDT) in a comprehensive panel of human cervical cancer-derived cell lines, including HeLa (HPV 18-positive), SiHa (HPV 16-positive), CaSki (HPV 16 and 18-positive), and C33A (HPV-negative), compared to a nontumorigenic human epithelial cell line (HaCaT). Were investigated: (i) cell cytotoxicity and phototoxicity, cellular uptake and subcellular distribution; (ii) cell death pathway and cellular oxidative stress; (iii) migration and invasion. Our results showed that HYP/P123 micelles had effective and selective time- and dose-dependent phototoxic effects on cervical cancer cells but not in HaCaT. Moreover, HYP/P123 micelles accumulated in endoplasmic reticulum, mitochondria and lysosomes, resulting in photodynamic cell death mainly by necrosis. HYP/P123 induced cellular oxidative stress mainly via type II mechanism of PDT and inhibited cancer cell migration and invasion mainly via MMP-2 inhibition. Taken together, our results indicate a potentially useful role of HYP/P123 micelles as a platform for HYP delivery to more specifically and effectively treat cervical cancers through PDT, suggesting they are worthy for in vivo preclinical evaluations.

New planar light source for the induction and monitoring of photodynamic processes in vitro

We recently developed a new light source that allows for the continuous monitoring of light-induced changes using common spectrophotometric devices adapted for microplate analyses. This source was designed primarily to induce photodynamic processes in cell models. Modern light components, such as LED chips, were used to improve the irradiance homogeneity. In addition, this source forms a small hermetic chamber and thus allows for the regulation of the surrounding atmosphere, which plays a significant role in these light-dependent reactions. The efficacy of the new light source was proven via kinetic measurements of reactive oxygen species generated during the photodynamic reaction of chloroaluminium phthalocyanine disulfonate (ClAlPcS₂) in three cell lines: human melanoma cells (G361), human breast adenocarcinoma cells (MCF7), and human fibroblasts (BJ).

Physicochemical stability of bioadhesive thermoresponsive platforms for methylene blue and hypericin delivery in photodynamic therapy

Hypericin (Hyp), a natural hydrophobic and photoactive pigment, and methylene blue (MB), a hydrophilic cationic dye, are utilized as photosensitizer (PS) for photodynamic therapy of cancer. Bioadhesive and thermoresponsive polymeric systems can improve the drug availability by increasing the contact time between the system and the mucosa and also controlling the drug release. In this work, an accelerated physicochemical stability study of binary polymeric systems composed of poloxamer 407 (Polox) and Carbopol 934 P (Carb) for MB or Hyp release was performed. Formulations were prepared containing Polox (20%, w/w), Carb (0.15%, w/w) and MB (0.25%, w/w) or Hyp (0.01%, W/W) and submitted to different stress conditions (5 ± 3 °C, 25 ± 2 °C and 40 ± 2 °C with relative humidity of 75 ± 5%) during 180 days. The samples were analyzed as macroscopic characteristics, photosensitizer content and mechanical properties by texture profile analysis. Both systems displayed decrease of photosensitizer content less than 5% during 180 days. MB-system showed an undefined reaction model, while Hyp-system displayed PS decay following a pseudo first-order reaction. Systems also displayed stable mechanical characteristics. The pharmaceutical analyses showed the good physicochemical stability of the bioadhesive platform for delivery Hyp and MB in photodynamic therapy.

Selective Photodynamic Effects on Breast Cancer Cells Provided by p123 Pluronic®- Based Nanoparticles Modulating Hypericin Delivery

BACKGROUND

Breast cancer is the most relevant type of cancer and the second cause of cancer- related deaths among women in general. Currently, there is no effective treatment for breast cancer although advances in its initial diagnosis and treatment are available. Therefore, the value of novel anti-tumor therapeutic modalities remains an immediate unmet need in clinical practice. Following our previous work regarding the properties of the Pluronics with different photosensitizers (PS) for photodynamic therapy (PDT), in this study we aimed to evaluate the efficacy of supersaturated hypericin (HYP) encapsulated on Pluronic® P123 (HYP/P123) against breast cancer cells (MCF-7) and non-tumorigenic breast cells (MCF-10A).

METHODS

Cell internalization and subcellular distribution of HYP/P123 was confirmed by fluorescence microscopy. The phototoxicity and citototoxicity of HYP/P123 was assessed by trypan blue exclusion assay in the presence and absence of light. Long-term cytotoxicity was performed by clonogenic assay. Cell migration was determined by the wound-healing assay. Apoptosis and necrosis assays were performed by annexin VFITC/ propidium Iodide (PI) by fluorescence microscopy.

RESULTS

Our results showed that HYP/P123 micelles had high stability and high rates of binding to cells, which resulted in the selective internalization in MCF-7, indicating their potential to permeate the membrane of these cells. Moreover, HYP/P123 micelles accumulated in mitochondria and endoplasmic reticulum organelles, resulting in the photodynamic cell death by necrosis. Additionally, HYP/P123 micelles showed effective and selective time- and dose dependent phototoxic effects on MCF-7 cells but little damage to MCF-10A cells. HYP/P123 micelles inhibited the generation of cellular colonies, indicating a possible capability to prevent the recurrence of breast cancer. We also demonstrated that HYP/P123 micelles inhibit the migration of tumor cells, possibly by decreasing their ability to form metastases.

CONCLUSION

Taken together, the results presented here indicate a potentially useful role of HYP/P123 micelles as a platform for HYP delivery to more specifically and effectively treat human breast cancers through photodynamic therapy, suggesting they are worthy for in vivo preclinical evaluations.

Wild-type and mutant p53 differentially modulate miR-124/iASPP feedback following pohotodynamic therapy in human colon cancer cell line

Colorectal cancer (CRC) is a most common digestive system malignant tumor. p53 mutation has essential role in cancers and is frequently observed in CRC and presents a huge challenge. p53 mutation has been reported to attenuate the inhibitory effect of photofrin-based photodynamic therapy (PDT). p53 mutation-induced gain of function brings up the dysfunction of carcinogenic factors, including miRNAs. Our research found that PDT suppressed CRC cell viability, reduced the tumor size and prolonged the survival time, all of which could be attenuated by p53 mutation or deletion. After p53 mutation or deletion, several miRNA expression levels were downregulated, among which miR-124 was the most strongly downregulated, whereas iASPP expression was upregulated. p53 binds to the promoter of miR-124 to promote its expression and then inhibited iASPP expression, so as to amplify the inhibitory effect of PDT on wild-type p53 cells. In p53-mutant or -deleted cells, this binding no longer worked to promote miR-124 expression, and iASPP expression increased, finally resulted in promoted CRC cell viability upon PDT. The interactive modulation among miR and iASPP in p53-mutant or -deleted cells may serve as a crucial pathway, which mediates therapy resistance when p53 is mutated or deleted, in the process of PDT treatment of CRC.

Comparative in vitro study of photodynamic activity of hypericin and hypericinates in MCF-7 cells

In this work we present a comparative in vitro study of photodynamic activity between hypericin (HYP) and some hypericinates (hypericin ionic pair with lysine or N-methylglucamine) in human mammary adenocarcinoma cells (MCF-7). The toxicity and phototoxicity of hypericin and hypericinates were compared, as well as their cellular uptake and localization and mutagenic, genotoxic and clonogenic capacity. Our results demonstrate that different cationic moieties promote differences in the hypericinate solubility in a biological environment, and can influence the cellular localization and the phototoxicity of the photosensitizer. It was verified that hypericinates have better efficiency to generate singlet oxygen than HYP, and a lower aggregation in biological medium. In vitro assays have shown that HYP and the hypericinates are able to permeate the MCF-7 cell membrane and accumulated in organelles near the nucleus. The difference in location, however, was not determinant to the cell death mechanism, and a higher prevalence of apoptosis for all studied compounds occurred. The photodynamic studies indicated that hypericinates were more effective than HYP and were able to inhibit the formation of cellular colonies, suggesting a possible ability to prevent the recurrence of tumors. It also appears that all compounds have relative safety for mutagenicity and genotoxicity, which opens up a further safe route for application in in vivo studies.

Hypericin-mediated photodynamic therapy induces apoptosis in K562 human leukemia cells through JNK pathway modulation

Hypericin (Hyp) is traditionally used as an antidepressant and antiviral agent. It selectively accumulates in spheroids and is also used as a photosensitizer in the photodynamic therapy of cancer. The present study aimed to investigate the cytotoxic effect of Hyp-mediated photodynamic therapy (Hyp-PDT) on cell growth and apoptosis of K562 leukemia cells, and to examine the underlying mechanisms. Hyp-PDT was performed with different light intensities (0.1, 0.3 and 0.5 mW/cm²), different concentrations of Hyp (0, 0.2, 0.4 and 0.8 µg/ml) and different durations of irradiation (0, 2, 4 and 8 min) in order to select the optimal conditions for subsequent experiments. A concentration of 0.4 µg/ml Hyp with a 5 h drug-light interval and 4 min irradiation at 0.3 mW/cm² light intensity was selected as the optimal conditions. The effects of Hyp-PDT on apoptosis were determined by detecting morphological changes under microscopy and by performing western blot analysis. The results revealed that Hyp-PDT suppressed cell viability in a light intensity-, dose- and irradiation duration-dependent manner. The expression levels of cleaved caspase-9, cleaved caspase-3 and phosphorylated-C-Jun N terminal kinase (JNK) l were significantly upregulated following Hyp-PDT. These results indicated that Hyp-PDT decreased cell viability and induced mitochondria-caspase-dependent apoptosis in the K562 cells through regulation of the JNK pathway. These findings suggest that Hyp-PDT may be developed as an effective treatment for leukemia.