Cytotoxicity Of Photodynamic Therapy Research Articles

The contradictory role of febuxostat in ABCG2 expression and potentiating hypericin-mediated photodynamic therapy in colorectal cancers.

Photodynamic Therapy (PDT) is an emerging method to treat colorectal cancers (CRC). Hypericin (HYP) is an effective mediator of PDT and the ABCG2 inhibitor, Febuxostat (FBX) could augment PDT. HT29 and HEK293 cells showed light dependant cytotoxic response to PDT in both 2D and 3D cell models. FBX co-treatment was not found to improve PDT cytotoxicity. Next, ABCG2 protein expression was observed in HT29 but not in HEK293 cells. However, ABCG2 gene expression analysis did not support protein expression results as ABCG2 gene expression results were found to be higher in HEK293 cells. Although HYP treatment was found to significantly reduce ABCG2 gene expression levels in both cell lines, FBX treatment partially restored ABCG2 gene expression. Our findings indicate that FBX co-treatment may not be suitable for augmenting HYP-mediated PDT in CRC but could potentially be useful for other applications.

Mechanistic investigation of photodynamic therapy using Visudyne in human KB carcinoma cells

Photodynamic therapy is a therapy that utilizes a specialized drug, a photosensitizer, which is not toxic by itself, but upon activation with light, is activated and leads to the production of singlet oxygen species. This production of singlet oxygen species starts a cascade that leads to cell death. Photodynamic therapy is a potential treatment for cancer patients, and it might be helpful to promote human health by providing alternative treatment to cancer. In-vitro study with Visudyne (VD) in KB carcinoma cells unveiled the mechanism of cell injury to cell death upon photodynamic therapy (PDT). In this study, we investigated real time monitoring of the production of singlet oxygen (SO), reactive oxygen species (ROS), mitochondria integrity and chromatin integrity in VD treated live cells by irradiating with a mercury lamp light source and 665–675 nm and 480–560 nm emission filter. Upon PDT we also observed cytoskeleton remodeling and cytochrome –C release using immunofluorescence techniques. We investigate the cytotoxicity of PDT and performed quantitative analysis for SO, ROS and mitochondrial potential change using colocalization analysis between VD and mitochondria.

The effectiveness of antimicrobial photodynamic therapy with prodigiosin against reference strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.

Prodigiosin (PG) is a secondary metabolite of bacterial origin that is able to absorb the visible light and plays a role as a photosensitizer in photodynamic therapy (PDT). This in vitro study aimed to investigate the cytotoxicity of PG-mediated PDT against the reference strains of Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PG were determined. Each strain was then allocated into four groups as follows: G1: control (no treatment), G2: PG-treated groups that received different PG concentrations (1000-1.95μM), G3: laser-treated group (wavelength: 520nm, radiation dose: 187J/cm2), and G4: PG-mediated PDT groups that were initially treated with different concentrations of PG and were then exposed to laser irradiation in the same way as the previous group. Finally, the number of colony-forming units per milliliter (CFU/mL) was calculated and analyzed using the SPSS software. PG had both bacteriostatic and bactericidal activities on the tested bacteria, with the maximum antibacterial effect being observed against S. aureus. In all bacterial strains, the maximum number of CFUs was observed in the control group followed by the laser-irradiated and PG-treated groups, but the differences were not statistically significant (p > 0.05). However, the utilization of PG-mediated PDT resulted in a significant decrease in the mean number of CFUs in all the tested bacteria (p < 0.0001). PG-mediated PDT had the potential to kill some bacterial strains in the laboratory. Yet, further studies are warranted to confirm its efficacy and safety to be applied in clinical settings.

Brain extracellular matrix attenuates photodynamic cytotoxicity of glioma cells

Glioma is the most common tumor in the central nervous system, which is often accompanied by poor prognosis. Brain extracellular matrix (ECM) plays an important role in regulating the growth and migration of glioma. Photodynamic therapy (PDT) has been an effective method for the treatment of solid tumors by oxidative modifications in recent years, and ECM may have an impact on the cytotoxicity of photodynamic therapy. In this work, we prepared decellularized brain ECM by chemical method to investigate the influence of the photodynamic effect of glioma C6 cells. Compared with decellularized liver ECM, brain ECM reduces PDT cytotoxicity. By observing the content of reactive oxygen species produced by near-infrared light active indocyanine green in cells, it was found that ECM did not affect the production of reactive oxygen species. Therefore, it is speculated that brain ECM may enhance the oxidative stress adaptability of glioma cells through potential signal regulation, or protect photodynamic targeting biomolecules (such as proteins and other cellular components) from oxidation in PDT mediated by indocyanine green and 808 nm laser in glioma cells.

Acetic acid enhances the effect of photodynamic therapy in gastric cancer cells via the production of reactive oxygen species.

Acetic acid is a major component of vinegar and is reported to have beneficial health effects. Notably, it causes oxidative stress and enhances the production of reactive oxygen species (ROS) in gastric cancer cells. ROS play important roles in cellular signal transduction, resulting in the regulation of protein expression and apoptosis. We previously reported that ROS upregulate heme carrier protein 1 (HCP1). Moreover, ROS increase the cellular uptake of porphyrins, which are precursors of heme and substrates for uptake by HCP1. Therefore, we hypothesized that photodynamic therapy (PDT) for cancer treatment using laser irradiation and photosensitizers, such as porphyrin, is enhanced via ROS produced by acetic acid. Herein, we used the rat gastric mucosal cells, RGM1, its cancer-like mutated cells, RGK1, and a manganese superoxide dismutase (MnSOD)-overexpressing RGK cell line, RGK-MnSOD. We confirmed that cancer-specific cellular uptake of porphyrin is increased upon acetic acid treatment and enhances the PDT cytotoxicity in RGK-1, not in RGM-1 and RGK-MnSOD. We believe that this occurs because of the overproduction of ROS and subsequent upregulation of HCP1 in cancerous cells. In conclusion, acetic acid can elevate the effect of PDT by inducing cancer-specific HCP1 expression via ROS production.

Assessment of natural antioxidants' effect on PDT cytotoxicity through fluorescence microscopy image analysis.

Photodynamic therapy (PDT) is a cancer treatment modality mediated by reactive oxygen species (ROS). However, the intracellular antioxidant defense system antagonizes PDT-generated ROS, impeding PDT efficacy. This study aimed to evaluate the enhancement of PDT cytotoxicity by its combination with natural antioxidants in pro-oxidant concentrations. A rich natural antioxidant mixture originating from Pinus halepensis bark extract was studied for its potential to enhance the efficacy of m-tetrahydroxyphenylchlorin (m-THPC)-PDT on LNCaP prostate cancer cells, in vitro. Various P. halepensis concentrations, at two different incubation times, were used in combination with m-THPC-PDT. Assessment of cellular viability and intracellular ROS levels evaluated the treatments' outcome. A novel method was developed for the assessment of the intracellular ROS levels, based on image analysis and data extraction from fluorescence microscopy images. P. halepensis bark extract increased the intracellular ROS levels in a concentration-dependent but not in an incubation-dependent manner. The higher concentrations used (≥50 μg/ml) reduced cellular viability even by 50%. One hour pretreatment with 30 μg/ml P. halepensis before m-THPC-PDT exceeded the levels of cellular death by approximately 15%. The results provided evidence of the cytotoxic effect of P. halepensis bark extract on LNCaP cells, showing the potential of P. halepensis to be used as an anticancer agent in prostate cancer treatment. The results also provided evidence of enhancement of m-THPC-PDT by P. halepensisbark extract showed the potential to be used as a supplementary agent to improve prostate cancer PDT treatment.

Porphylipoprotein Accumulation and Porphylipoprotein Photodynamic Therapy Effects Involving Cancer Cell-Specific Cytotoxicity.

In photodynamic therapy (PDT) for neoplasms, photosensitizers selectively accumulate in cancer tissue. Upon excitation with light of an optimal wavelength, the photosensitizer and surrounding molecules generate reactive oxygen species, resulting in cancer cell-specific cytotoxicity. Porphylipoprotein (PLP) has a porphyrin-based nanostructure. The porphyrin moiety of PLP is quenched because of its structure. When PLP is disrupted, the stacked porphyrins are separated into single molecules and act as photosensitizers. Unless PLP is disrupted, there is no photosensitive disorder in normal tissues. PLP can attenuate the photosensitive disorder compared with other photosensitizers and is ideal for use as a photosensitizer. However, the efficacy of PLP has not yet been evaluated. In this study, the mechanism of cancer cell-specific accumulation of PLP and its cytotoxic effect on cholangiocarcinoma cells were evaluated. The effects were investigated on normal and cancer-like mutant cells. The cytotoxicity effect of PLP PDT in cancer cells was significantly stronger than in normal cells. In addition, reactive oxygen species regulated intracellular PLP accumulation. The cytotoxic effects were also investigated using a cholangiocarcinoma cell line. The cytotoxicity of PLP PDT was significantly higher than that of laserphyrin-based PDT, a conventional type of PDT. PLP PDT could also inhibit tumor growth in vivo.

Immune Reprogramming Precision Photodynamic Therapy of Peritoneal Metastasis by Scalable Stem-Cell-Derived Extracellular Vesicles

The dissemination of tumor metastasis in the peritoneal cavity, also called peritoneal metastasis (PM) or carcinomatosis, represents a late stage of gastrointestinal and gynecological cancer with very poor prognosis, even when cytoreductive surgery is effective, due to residual microscopic disease. Photodynamic therapy (PDT) in the management of peritoneal metastasis has been clinically limited by the low tumor selectivity of photosensitizers (PS) and important adverse effects. Here, we propose extracellular nanovesicles (EVs) derived from mesenchymal stem/stromal cells (MSCs) as the fourth generation of immune active PS vectors that are able to target peritoneal metastasis with superior selectivity, potentiate PDT cytotoxicity at the tumor site without affecting healthy tissues, modulate the tumor microenvironment of immunocompetent colorectal and ovarian carcinomatosis models, and promote an antitumor immune response. A pioneering strategy was developed for high yield, large-scale production of MSC-EVs encapsulating the drug meta(tetrahydroxyphenyl)chlorin (mTHPC) (EVs-mTHPC) that is compatible with requirements of clinical translation and also preserves the topology and integrity of naturally produced EVs. Intraperitoneal injection of EVs-mTHPC showed an impressive enhancement of tumoral selectivity in comparison to the free drug and to the liposomal formulation Foslip (mean ratio of PS in tumors/organs of 40 for EVs-mTHPC versus 1.5 for the free PS and 5.5 for Foslip). PDT mediated by EVs-mTHPC permitted an important tumoral necrosis (55% of necrotic tumoral nodules versus 18% for Foslip (p < 0.0001)) and promoted antitumor immune cell infiltration, mainly proinflammatory M1-like CD80+ and CD8+ T cell effector. Intratumor proliferation was significantly decreased after PDT with EVs-mTHPC. Overall EVs vectorization of mTHPC afforded important tumoral selectivity while overcoming the PDT toxicity of the free drug and prolonged mice survival in the colorectal carcinomatosis model. MSC-EVs produced by our scalable manufacturing method appears like the clinically relevant fourth-generation PDT vehicle to overcome current limitations of PDT in the treatment of peritoneal metastasis and promote a hot tumor immune environment in PM.

Epigallocatechin Gallate Enhances MAL-PDT Cytotoxic Effect on PDT-Resistant Skin Cancer Squamous Cells.

Photodynamic therapy (PDT) has been used to treat certain types of non-melanoma skin cancer with promising results. However, some skin lesions have not fully responded to this treatment, suggesting a potential PDT-resistant phenotype. Therefore, novel therapeutic alternatives must be identified that improve PDT in resistant skin cancer. In this study, we analyzed the cell viability, intracellular protoporphyrin IX (PpIX) content and subcellular localization, proliferation profile, cell death, reactive oxygen species (ROS) detection and relative gene expression in PDT-resistant HSC-1 cells. PDT-resistant HSC-1 cells show a low quantity of protoporphyrin IX and low levels of ROS, and thus a low rate of death cell. Furthermore, the resistant phenotype showed a downregulation of HSPB1, SLC15A2, FECH, SOD2 and an upregulation of HMBS and BIRC5 genes. On the other hand, epigallocatechin gallate catechin enhanced the MAL-PDT effect, increasing levels of protoporphyrin IX and ROS, and killing 100% of resistant cells. The resistant MAL-PDT model of skin cancer squamous cells (HSC-1) is a reliable and useful tool to understand PDT cytotoxicity and cellular response. These resistant cells were successfully sensitized with epigallocatechin gallate catechin. The in vitro epigallocatechin gallate catechin effect as an enhancer of MAL-PDT in resistant cells is promising in the treatment of difficult skin cancer lesions.

Effective Combined Photodynamic Therapy with Lipid Platinum Chloride Nanoparticles Therapies of Oral Squamous Carcinoma Tumor Inhibition.

Encapsulating cisplatin (CDDP) into liposomes to form lipid-platinum-chloride nanoparticles (LPC NPs) has shown a promising anticancer effect in melanoma, bladder, and liver cancer models. This promising anticancer effect of LPC NPs challenges us to study its implications in combination with photodynamic therapy (PDT). Herein, we report the therapeutic efficacy of PDT+LPC on a xenograft model of oral squamous cell carcinoma (OSCC). Results showed that PDT+LPC significantly reduced the tumor volume by up to ~112%. Meanwhile, LPC, PDT+CDDP, or the CDDP group showed ~98.8%, ~73.1%, or ~39.5% volume reductions, respectively. Histological examination suggests that PDT+LPC or LPC treatment showed minimal side effects on renal damage compared to either CDDP or the PDT+CDDP group. Immunohistochemistry staining (IHC) staining on Ki-67, CD31, cleaved caspase-3, TUNEL assays, and western blots of tumor suppressor p53 confirmed consistent results. Most importantly, PDT+LPC prolonged tumor growth inhibition, which leads to minimum chemotherapy treatment administrations. Results suggest that PDT cytotoxicity provided a potent additive effect towards chemotherapy efficacy. Therefore, combined PDT with LPC NPs enhanced the therapeutic outcome in human OSCC.

Antimalarial Drugs Enhance the Cytotoxicity of 5-Aminolevulinic Acid-Based Photodynamic Therapy against the Mammary Tumor Cells of Mice In Vitro.

Artemisinin and its derivatives, including artesunate (ART) and artemether (ARM), exert anticancer effects in the micromolar range in drug and radiation-resistant cell lines. Artemisinin has been reported to sensitize cervical cancer cells to radiotherapy. In the present study, we determined whether ART and ARM could enhance the cytotoxicity of 5-aminolevulinic acid (5-ALA)-based photodynamic therapy (PDT) against the mammary tumor cells of mice. The corrected PpIX fluorescence intensities in the control, 5-ALA, 5-ALA + ART, and 5-ALA + ARM groups were 3.385 ± 3.730, 165.7 ± 33.45, 139.0 ± 52.77, and 165.4 ± 51.10 a.u., respectively. At light doses of 3 and 5 J/cm2, the viability of 5-ALA-PDT-treated cells significantly decreased with ART (p < 0.01 and p < 0.01) and ARM treatment (p < 0.01 and p < 0.01). Besides, the number of annexin V-FITC and ethidium homodimer III-positive cells was greater in the 5-ALA-PDT with ARM group than that in the other groups. N-acetylcysteine could not significantly inhibit the percentages of apoptotic cells or inviable cells induced by 5-ALA-PDT with ARM. These reactive oxygen species-independent mechanisms might enhance cytotoxicity in 5-ALA-PDT with ARM-treated tumor cells, suggesting that the use of 5-ALA-PDT with ARM could be a new strategy to enhance PDT cytotoxicity against tumor cells. However, as these results are only based on in vitro studies, further in vivo investigations are required.

The role of ABCG2 in modulating responses to anti-cancer photodynamic therapy.

The ATP-binding cassette (ABC) superfamily G member 2 (ABCG2) transmembrane protein transporter is known for conferring resistance to treatment in cancers. Photodynamic therapy (PDT) is a promising anti-cancer method involving the use of light-activated photosensitisers to precisely induce oxidative stress and cell death in cancers. ABCG2 can efflux photosensitisers from out of cells, reducing the capacity of PDT and limiting the efficacy of treatment. Many studies have attempted to elucidate the relationship between the expression of ABCG2 in cancers, its effect on the cellular retention of photosensitisers and its impact on PDT. This review looks at the studies which investigate the effect of ABCG2 on a range of different photosensitisers in different pre-clinical models of cancer. This work also evaluates the approaches that are being investigated to address the role of ABCG2 in PDT with an outlook on potential clinical validation.

Nitric oxide regulates the expression of heme carrier protein-1 via hypoxia inducible factor-1α stabilization.

Photodynamic therapy (PDT) is a cancer therapy that capitalizes on cancer-specific porphyrin accumulation. We have investigated this phenomenon to propose the following three conclusions: 1) the mechanism underlying this phenomenon is closely related to both nitric oxide (NO) and heme carrier protein-1 (HCP-1), 2) NO inactivates ferrochelatase, and thus, the intracellular porphyrin levels in the cells are increased by the administration of an NO donor after 5-aminolevulinic acid treatment, 3) HCP-1 transports not only heme but also other porphyrins. Since NO stabilizes hypoxia-inducible factor (HIF)-1α, resulting in the upregulation of heme biosynthesis, HCP-1 expression can be increased by HIF-1α stabilization. In this study, we determined whether NO regulates HCP-1 expression by stabilizing HIF-1α expression. For this purpose, rat gastric cancer cell line RGK36 was treated with L-arginine or N6-(1-iminoethyl)-L-lysine (L-NIL). L-arginine treatment increased the intracellular NO concentration, and both HCP-1 and HIF-1α expression, while L-NIL treatment decreased them. Cytotoxicity of PDT was enhanced by L-arginine, following intracellular hemato-porphyrin dihydrochloride (HpD) accumulation. Both Cytotoxicity of PDT and HpD accumulation were decreased by L-NIL. The HCP-1 and HIF-1α expression, intracellular HpD accumulation and PDT cytotoxicity were decreased by 2-methoxyestradiol, which is a HIF-1α inhibitor. Moreover, these phenomena were not increased by a combination of both L-arginine and 2-Me. Thus, HCP-1 can be a downstream target of HIF-1α. These effects were also induced in the human gastric cancer cell line MKN45. Taken together, we conclude that HCP-1 expression is regulated by NO via HIF-1α stabilization.

Hydrophobic IR780 loaded sericin nanomicelles for phototherapy with enhanced antitumor efficiency

The near-infrared dye, IR780 iodide, has been utilized in photodynamic therapy (PDT) and photothermal therapy (PTT). However, the hydrophobicity and photosensitivity of IR780 limit its further applications in biomedical fields. Herein, the hydrophilic sericin was modified with hydrophobic cholesterol to form an amphiphilic macromolecular conjugate (Ser-Chol). The tumor-targeting agent, folic acid (FA), was further linked to the conjugate (FA-Ser-Chol). The IR780 could be encapsulated into such amphiphilic macromolecule to form stable micelles (FA-Ser-Chol/IR780) by self-assembly, and the solubility and photo-stability of IR780 were greatly improved. The FA-Ser-Chol/IR780 micelles could be efficiently absorbed by FA-positive gastric cancer cells (BGC-823) through FA receptors, while the uptake micelles showed remarkable PDT and PTT cytotoxicity towards BGC-823 cells under laser irradiation of 808 nm. Therefore, FA-Ser-Chol micelles may serve as a promising IR780 carrier for PDT and PTT therapy.

Hyperthermia enhances photodynamic therapy by regulation of HCP1 and ABCG2 expressions via high level ROS generation

Photodynamic therapy (PDT) is a cancer treatment that make use of the cancer-specific accumulation of porphyrins. We have reported that mitochondrial reactive oxygen species (mitROS) upregulate uptake transporter of porphyrins, heme carrier protein-1 (HCP-1). The accumulation of cancer-specific porphyrins was increased by mitROS production, thereby the cancer-specific PDT cytotoxicity was enhanced. Thus we investigated whether mitROS production by hyperthermia can enhanced the cytotoxicity of PDT or not. In this study, 1 h of hyperthermia at 42 °C increased the mitROS production, and both the accumulation of cancer-specific porphyrins and the PDT cytotoxicity increased. Moreover, the authors treated cells with N-acetyl-L-cysteine (NAC) to examine the effect of mitROS. NAC inhibited the increasing ROS production after hyperthermia to restrain the post-treatment increase of cancer-specific porphyrins accumulation. Moreover, the increase of ROS production in cancer cells after hyperthermia upregulated HCP-1 expression and downregulated ABCG2 expression. These regulation were inhibited by NAC. These results suggest that hyperthermia treatment increased mitROS production, which involved HpD accumulation and enhanced PDT effects in cancer cells. The mechanism of this phenomenon was most likely to be due to both the upregulation of HCP-1 and the downregulation of ABCG2 by mitROS.

Modeling Epidermal Growth Factor Inhibitor-mediated Enhancement of Photodynamic Therapy Efficacy Using 3D Mesothelioma Cell Culture.

We have demonstrated that lung-sparing surgery with intraoperative photodynamic therapy (PDT) achieves remarkably extended survival for patients with malignant pleural mesothelioma (MPM). Nevertheless, most patients treated using this approach experience local recurrence, so it is essential to identify ways to enhance tumor response. We previously reported that PDT transiently activates EGFR/STAT3 in lung and ovarian cancer cells and inhibiting EGFR via erlotinib can increase PDT sensitivity. Additionally, we have seen higher EGFR expression associating with worse outcomes after Photofrin-mediated PDT for MPM, and the extensive desmoplastic reaction associated with MPM influences tumor phenotype and therapeutic response. Since extracellular matrix (ECM) proteins accrued during stroma development can alter EGF signaling within tumors, we have characterized novel 3D models of MPM to determine their response to erlotinib combined with Photofrin-PDT. Our MPM cell lines formed a range of acinar phenotypes when grown on ECM gels, recapitulating the locally invasive phenotype of MPM in pleura and endothoracic fascia. Using these models, we confirmed that EGFR inhibition increases PDT cytotoxicity. Together with emerging evidence that EGFR inhibition may improve survival of lung cancer patients through immunologic and direct cell killing mechanisms, these results suggest erlotinib-enhanced PDT may significantly improve outcomes for MPM patients.

Hybrid Nanomedicine Fabricated from Photosensitizer-Terminated Metal-Organic Framework Nanoparticles for Photodynamic Therapy and Hypoxia-Activated Cascade Chemotherapy.

During photodynamic therapy (PDT), severe hypoxia often occurs as an undesirable limitation of PDT owing to the O2 -consuming photodynamic process, compromising the effectiveness of PDT. To overcome this problem, several strategies aiming to improve tumor oxygenation are developed. Unlike these traditional approaches, an opposite method combining hypoxia-activated prodrug and PDT may provide a promising strategy for cancer synergistic therapy. In light of this, azido-/photosensitizer-terminated UiO-66 nanoscale metal-organic frameworks (UiO-66-H/N3 NMOFs) which serve as nanocarriers for the bioreductive prodrug banoxantrone (AQ4N) are engineered. Owing to the effective shielding of the nanoparticles, the stability of AQ4N is well preserved, highlighting the vital function of the nanocarriers. By virtue of strain-promoted azide-alkyne cycloaddition, the nanocarriers are further decorated with a dense PEG layer to enhance their dispersion in the physiological environment and improve their therapeutic performance. Both in vitro and in vivo studies reveal that the O2 -depleting PDT process indeed aggravates intracellular/tumor hypoxia that activates the cytotoxicity of AQ4N through a cascade process, consequently achieving PDT-induced and hypoxia-activated synergistic therapy. Benefiting from the localized therapeutic effect of PDT and hypoxia-activated cytotoxicity of AQ4N, this hybrid nanomedicine exhibits enhanced therapeutic efficacy with negligible systemic toxicity, making it a promising candidate for cancer therapy.

Highly Selective Photodynamic Therapy with a Short Drug-Light Interval Using a Cytotoxic Photosensitizer Porphyrus Envelope for Drug-Resistant Prostate Cancer Cells

Background: Photodynamic therapy (PDT) is a less invasive cancer treatment using photochemical reactions induced by light irradiation to a photosensitizer (PS). Highly selective PDT with fast accumulation of the PS in target site might be a promising treatment option for drug-resistant prostate cancer facing high incidence rate of elderly men who have no effective treatment options and require a minimally invasive treatment. Hemagglutinating virus of Japan envelope (HVJ-E) allows selective and fast drug delivery to the drug-resistant prostate cancer cells via rapid cell membrane fusion. PS named porphyrus envelope (PE) has been developed by insertion of lipidated protoporphyrin IX (PpIX lipid) into HVJ-E. In this study, we investigated the optimal conditions for PE preparation and laser irradiation for highly selective PDT using PE with a short drug-light interval. Materials and Methods: Human hormon refractory prostate cancer cell line PC-3 and human normal prostate epithelial cell line PNT2 were cultured. PpIX lipid uptake and cytotoxicity of PDT in the cells incubated with PE for 10 min were evaluated by measuring fluorescence intensity and by using a cell counting reagent 24 h after PDT, respectively. Results: PpIX lipid uptake and cytotoxicity of PDT were increased with PpIX lipid concentration. Cytotoxicity of PDT using PE was more than 9 times as strong as that with PpIX lipid and PpIX induced by 5-aminolevulinic acid. Much stronger cytotoxicity was induced in PC-3 cells than PNT2 cells with the ratio of cell death rate for cancer to normal cells up to 4.64 ± 0.09. Conclusions: Fast PS delivery with HVJ-E allows highly selective PDT with a short drug-light interval. Therefore, PDT using PE has a potential to shorten treatment period and reduce side effects of PDT.

The water soluble axially disubstituted silicon phthalocyanines: photophysicochemical properties and in vitro studies.

Two novel silicon(IV) phthalocyanines bearing 1,3-bis[3(dimethylamino)phenoxy]propan-2-ol or 1,3-bis[3(diethylamino)phenoxy]propan-2-ol groups at their axial positions were synthesized. These phthalocyanines were converted into their water soluble derivatives by the quaternization reaction with methyl iodide. The quaternized phthalocyanines show excellent solubility aqueous solutions without any aggregation which makes them potential photosensitizers for use in photodynamic therapy (PDT). For this reason, the photophysical and photochemical properties such as fluorescence quantum yields, lifetimes, singlet oxygen generation and photodegradation of both non-ionic (3 and 5) and quaternized cationic silicon(IV) phthalocyanines were investigated. Furthermore, the cytotoxicity of PDT was determined by colorimetric proliferation assay against to hepatocellular carcinoma (HuH-7) cancer cells. In this study, the cells were incubated with a novel water soluble silicon(IV) phthalocyanine derivatives and thereafter the cells were illuminated using broad-band incoherent light source.

Photodynamic Therapy with Liposomal Zinc Phthalocyanine and Tirapazamine Increases Tumor Cell Death via DNA Damage.

The efficacy of photodynamic therapy (PDT) in some solid tumors is limited by the poor biodistributive properties of conventional photosensitizers and a natural predisposition of tumor cells to survive hypoxia and oxidative stress. This study investigated the therapeutic potential of a third-generation photosensitizer, liposomal zinc phthalocyanine (ZnPC), in combination with the hypoxic cytotoxin tirapazamine (TPZ). TPZ induces DNA double strand breaks (DSBs) under hypoxic conditions and subsequent apoptosis via p53 signaling. Experiments were performed in tumor cells with functional p53 (Sk-Cha1) and dysfunctional p53 (A431). The combination therapy of TPZ and PDT induced DNA DSBs and cell cycle stalling and enhanced the cytotoxicity of PDT by exacerbating apopotic and non-apoptotic tumor cell death. These phenomena occurred regardless of oxygen tension and the mechanism of cell death differed per cell line. Liposomes containing both ZnPC and TPZ exhibited no dark toxicity but were more lethal to both cell types after PDT compared to ZnPC-liposomes lacking TPZ—an effect that was more pronounced under hypoxic conditions. In conclusion, TPZ is a suitable pharmaceutical compound to increase PDT efficacy by exploiting the post-PDT tumor hypoxia. The inclusion of TPZ and ZnPC into a single liposomal delivery system was feasible. The PDT strategy described in this study may be valuable for the treatment of PDT-recalcitrant tumors.