Phthalocyanine-mediated photodynamic therapy induces cell death and a G0/G1 cell cycle arrest in cervical cancer cells

Photoactive metabolite mediated photodynamic therapy of Rhabdomyosarcoma cell lines using medicinal plants and Doxorubicin co-treatments

BACKGROUND

Medicinal plant-mediated combinational therapies have gained importance globally due to minimal side effects and enhanced treatment outcomes compared to single-drug modalities. We aimed to analyze the cytotoxic potential of each conventional treatment i.e., photodynamic therapy (PDT), chemotherapy (doxorubicin hydrochloride; Dox-HCl) with or without various concentrations of medicinal plant extracts (PE) on soft tissue cancer Rhabdomyosarcoma (RD) cell line.

METHODS

The Rhabdomyosarcoma (RD) cell line was cultured and treated with Photosensitizer (Photosense (AlPc4)), Chemo (Dox-HCl), and their combinations with different concentrations of each plant extract i.e., Thuja occidentalis, Moringa oleifera, Solanum surattense. For the source of illumination, a Diode laser (λ = 630 nm ± 1 nm, Pmax = 1.5 mW) was used. Photosensitizer uptake time (∼ 45 min) was optimized through spectrophotometric measurements (absorption spectroscopy). Drug response of each treatment arm was assessed post 24 h of administration using 3-(4, 5-dimethyl-2-thiazolyl)-2, 5- 5-diphenyl-2 H- tetrazolium bromide (MTT) assay.

RESULTS

PE-mediated Chemo-Photodynamic therapy (PDT) exhibited synergistic effects (CI < 1). Moreover, Rhabdomyosarcoma culture pretreated with various plant extracts for 24 h exhibited significant inhibition of cell viability however most effective outcomes were shown by low and high doses of Moringa oleifera compared to other plant extracts. Post low doses treated culture with all plant extracts followed by PDT came up with more effectiveness when compared to all di-therapy treatments.

CONCLUSION

The general outcome of this work shows that the ethanolic plant extracts (higher doses) promote the death of cancerous cells in a dose-dependent way and combining Dox-HCl and photo-mediated photodynamic therapy can yield better therapeutic outcomes.

Attritional evaluation of lipophilic and hydrophilic metallated phthalocyanines for oncological photodynamic therapy

BACKGROUND AND AIM

Oncological photodynamic therapy (PDT) relies on photosensitizers (PSs) to photo-oxidatively destroy tumor cells. Currently approved PSs yield satisfactory results in superficial and easy-to-access tumors but are less suited for solid cancers in internal organs such as the biliary system and the pancreas. For these malignancies, second-generation PSs such as metallated phthalocyanines are more appropriate. Presently it is not known which of the commonly employed metallated phtahlocyanines, namely aluminum phthalocyanine (AlPC) and zinc phthalocyanine (ZnPC) as well as their tetrasulfonated derivatives AlPCS4 and ZnPCS4, is most cytotoxic to tumor cells. This study therefore employed an attritional approach to ascertain the best metallated phthalocyanine for oncological PDT in a head-to-head comparative analysis and standardized experimental design.

METHODS

ZnPC and AlPC were encapsulated in PEGylated liposomes. Analyses were performed in cultured A431 cells as a template for tumor cells with a dysfunctional P53 tumor suppressor gene and EGFR overexpression. First, dark toxicity was assessed as a function of PS concentration using the WST-1 and sulforhodamine B assay. Second, time-dependent uptake and intracellular distribution were determined by flow cytometry and confocal microscopy, respectively, using the intrinsic fluorescence of the PSs. Third, the LC₅₀ values were established for each PS at 671 nm and a radiant exposure of 15 J/cm² following 1-h PS exposure. Finally, the mode of cell death as a function of post-PDT time and cell cycle arrest at 24 h after PDT were analyzed.

RESULTS

In the absence of illumination, AlPC and ZnPC were not toxic to cells up to a 1.5-μM PS concentration and exposure for up to 72 h. Dark toxicity was noted for AlPCS4 at 5 μM and ZnPCS4 at 2.5 μM. Uptake of all PSs was observed as early as 1 min after PS addition to cells and increased in amplitude during a 2-h incubation period. After 60 min, the entire non-nuclear space of the cell was photosensitized, with PS accumulation in multiple subcellular structures, especially in case of AlPC and AlPCS4. PDT of cells photosensitized with ZnPC, AlPC, and AlPCS4 yielded LC₅₀ values of 0.13 μM, 0.04 μM, and 0.81 μM, respectively, 24 h post-PDT (based on sulforhodamine B assay). ZnPCS4 did not induce notable phototoxicity, which was echoed in the mode of cell death and cell cycle arrest data. At 4 h post-PDT, the mode of cell death comprised mainly apoptosis for ZnPC and AlPC, the extent of which was gradually exacerbated in AlPC-photosensitized cells during 8 h. ZnPC-treated cells seemed to recover at 8 h post-PDT compared to 4 h post-PDT, which had been observed before in another cell line. AlPCS4 induced considerable necrosis in addition to apoptosis, whereby most of the cell death had already manifested at 2 h after PDT. During the course of 8 h, necrotic cell death transitioned into mainly late apoptotic cell death. Cell death signaling coincided with a reduction in cells in the G₀/G₁ phase (ZnPC, AlPC, AlPCS4) and cell cycle arrest in the S-phase (ZnPC, AlPC, AlPCS4) and G₂ phase (ZnPC and AlPC). Cell cycle arrest was most profound in cells that had been photosensitized with AlPC and subjected to PDT.

CONCLUSIONS

Liposomal AlPC is the most potent PS for oncological PDT, whereas ZnPCS4 was photodynamically inert in A431 cells. AlPC did not induce dark toxicity at PS concentrations of up to 1.5 μM, i.e., > 37 times the LC₅₀ value, which is favorable in terms of clinical phototoxicity issues. AlPC photosensitized multiple intracellular loci, which was associated with extensive, irreversible cell death signaling that is expected to benefit treatment efficacy and possibly immunological long-term tumor control, granted that sufficient AlPC will reach the tumor in vivo. Given the differential pharmacokinetics, intracellular distribution, and cell death dynamics, liposomal AlPC may be combined with AlPCS4 in a PS cocktail to further improve PDT efficacy.

Evaluation of histone deacetylase inhibitor substituted zinc and indium phthalocyanines for chemo- and photodynamic therapy

In this study, we synthesized and characterized 3-hydroxypyridin-2-thione (3-HPT) bearing zinc (ZnPc-1 and ZnPc-2) and indium (InPc-1 and InPc-2) phthalocyanine (Pc) derivatives, either non-peripherally or peripherally substituted as photosensitizer (PS) agents and evaluated their anti-cancer efficacy on two breast cancer cell lines, MDA-MB-231 and MCF-7 as well as a human endothelial cell line, HUVEC. Our results indicated different localization patterns between ZnPcs and InPcs in addition to enhanced effects on the mitochondrial network for InPcs. Moreover, peripheral or non-peripheral substitution of HDACi moieties altered cellular localization between ZnPc-1 and ZnPc-2, leading to increased IC₅₀ values along with decreased anti-cancer activity for non-peripheral substitution. When considering the compounds' differential effects in vitro, our data indicates that further research is required to determine the ideal Pcs for anti-cancer PDT treatments since the core metals of the compounds have affected the cellular localization, and positioning of the chemotherapeutic residues may inhibit cellular penetrance.

3-Hydroxypyridin-2-thione bearing zinc and indium phthalocyanine derivatives, as photosensitizer agents have been synthesized and evaluated for their anti-cancer efficacy on two breast cancer cell lines, MDA-MB-231 and MCF-7 as well as a human endothelial cell line, HUVEC.

A Translational Study of a Silicon Phthalocyanine Substituted with a Histone Deacetylase Inhibitor for Photodynamic Therapy

In this study, we synthesized and characterized a silicon phthalocyanine substituted with 3-hydroxypyridin-2-thione (SiPc-HDACi), designed to be a chemophotodynamic therapy agent acting as a histone deacetylase inhibitor, and we determined its photophysical, photochemical, and photobiological properties. Next, we evaluated its anticancer efficacy on MCF-7, double positive and MDA-MB-231, triple negative breast cancer cell lines, as well as on a healthy human endothelial cell line (HUVEC). Our results indicate that SiPc-HDACi can target nucleoli of cells, effectively inducing apoptosis while promoting cell cycle arrest thanks to its high singlet oxygen yield and its histone deacetylase downregulating properties, suggesting a powerful anticancer effect on breast cancer in vitro. Our further studies will be conducted with primary breast cancer cell culture to give a better insight into the anticancer mechanism of the compound.

Zinc(II) phthalocyanines as photosensitizers for antitumor photodynamic therapy

Photodynamic therapy (PDT) is a highly specific and clinically approved method for cancer treatment in which a nontoxic drug known as photosensitizer (PS) is administered to a patient. After selective tumor irradiation, an almost complete eradication of the tumor can be reached as a consequence of reactive oxygen species (ROS) generation, which not only damage tumor cells, but also lead to tumor-associated vasculature occlusion and the induction of an immune response. Despite exhaustive investigation and encouraging results, zinc(II) phthalocyanines (ZnPcs) have not been approved as PSs for clinical use yet. This review presents an overview on the physicochemical properties of ZnPcs and biological results obtained both in vitro and in more complex models, such as 3D cell cultures, chicken chorioallantoic membranes and tumor-bearing mice. Cell death pathways induced after PDT treatment with ZnPcs are discussed in each case. Finally, combined therapeutic strategies including ZnPcs and the currently available clinical trials are mentioned.

Synergistic Effect in Zinc Phthalocyanine—Nanoporous Gold Hybrid Materials for Enhanced Photocatalytic Oxidations

Nanoporous gold (npAu) supports were prepared as disks and powders by corrosion of Au-Ag alloys. The npAu materials have pore sizes in the range of 40 nm as shown by scanning electron microscopy (SEM). The surface was modified by a self-assembled monolayer (SAM) with an azidohexylthioate and then functionalized by a zinc (II) phthalocyanine (ZnPc) derivative using “click chemistry”. By atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) the content of zinc was determined and the amount of immobilized ZnPc on npAu was calculated. Energy-dispersive X-ray (EDX) spectroscopy gave information about the spatial distribution of the ZnPc throughout the whole porous structure. NpAu and ZnPc are both absorbing light in the visible region, therefore, the heterogeneous hybrid systems were studied as photocatalysts for photooxidations using molecular oxygen. By irradiation of the hybrid system, singlet oxygen is formed, which was quantified using the photooxidation of 1,3-diphenylisobenzofuran (DPBF) as a selective singlet oxygen quencher. The illuminated surface area of the npAu-ZnPc hybrid system and the coverage of the ZnPc were optimized. The synergistic effect between the plasmon resonance of npAu and the photosensitizer ZnPc was shown by selective irradiation and excitation of only the phthalocyanine, the plasmon resonance of the npAu support and both absorption bands simultaneously, resulting in an enhanced photooxidation activity by nearly an order of magnitude.

A New Tool in the Quest for Biocompatible Phthalocyanines: Palladium Catalyzed Aminocarbonylation for Amide Substituted Phthalonitriles and Illustrative Phthalocyanines Thereof

The amide peptide bond type linkage is one of the most natural conjugations available, present in many biological synthons and pharmaceutical drugs. Hence, aiming the direct conjugation of potentially biologically active compounds to phthalocyanines, herein we disclose a new strategy for direct modulation of phthalonitriles, inspired by an attractive synthetic strategy for the preparation of carboxamides based on palladium-catalyzed aminocarbonylation of aryl halides in the presence of carbon monoxide (CO) which, to our knowledge, has never been used to prepare amide-substituted phthalonitriles, the natural precursors for the synthesis of phthalocyanines. Some examples of phthalocyanines prepared thereof are also reported, along with their full spectroscopic characterization and photophysical properties initial assessment.

Effective phthalocyanines mediated photodynamic therapy with doxorubicin or methotrexate combination therapy at sub-micromolar concentrations in vitro

To improve a cancer patient's quality of life, short treatment duration resulting in rapid tumour removal while sparing normal tissue are highly desirable. Photodynamic therapy (PDT) commonly applied in a single treatment, while often effective can be limited at low photosensitizer or light doses. Combination therapies can overcome the efficacy limitations while not increasing treatment-associated morbidity. Here the efficacy of combination therapy comprised of doxorubicin (DOX) or methotrexate (MTX) with Photosens mediated PDT was investigated in three cell lines in vitro, employing multiple incubation sequences. Photosense is a mixture of aluminium phthalocyanines with different sulfonation. The results demonstrated higher synergistic effects when DOX or MTX-mediated chemotherapy preceded PDT light activation by 24 h. MTX is marginally more cytotoxic than DOX, when combined with Photosens (AlPcS_2-4) mediated PDT. While MTX and DOX exposure prior to AlPcS_2-4 incubation may enhance mitochondrial localisation photosensitizer, the simultaneous targeting of DNA, proteins, and lipids of the combination therapies leads to the observed high cytotoxicity at sub μM drug doses.

Porphyrinoid biohybrid materials as an emerging toolbox for biomedical light management

The present article reviews the most important developing strategies in light-induced nanomedicine, based on the combination of porphyrinoid photosensitizers with a wide variety of biomolecules and biomolecular assemblies.

Therapeutic Considerations and Conjugated Polymer-Based Photosensitizers for Photodynamic Therapy

Conjugated polymers have recently attracted a great deal of attention for applications in photodynamic therapy (PDT) because of their light-harvesting capability, efficient energy transfer, and singlet oxygen generation properties. This review describes recent advances in PDT development, including therapeutic mechanisms of PDT in cancer treatments, light excitation methods, and especially recent advances of conjugated polyelectrolytes and conjugated polymer nanoparticles as photosensitizers. The future direction on PDT and further development of conjugated polymer photosensitizers are discussed. The aim of this review is to stimulate innovative ideas to synthesize a new generation of conjugated polymer photosensitizers and promote their translation to clinical applications of PDT.

The interaction between the light source dose and caspase-dependent and -independent apoptosis in human SK-MEL-3 skin cancer cells following photodynamic therapy with zinc phthalocyanine: A comparative study

The aim of this study is to determine the behavior of relative expression of Bcl-2, caspase-8, caspase-9, and caspase-3 genes of/in SK-MEL-3 cancer cells and explore molecular mechanisms responsible for the apoptosis response during an in vitro photodynamic therapy (PDT) with Zinc Phthalocyanine (ZnPc) using different doses of the light source. In this study, firstly the cytotoxic effects of ZnPc-PDT on SK-MEL-3 cells were evaluated. By irradiating the laser, ZnPc induced a significant amount of apoptosis on SK-MEL-3 cells in three IC₅₀s including 0.064±0.01, 0.043±0.01, and 0.036±0.01μg/mL at the doses of 8, 16, and 24J/cm², respectively. Moreover, flow cytometry and QRT-PCR experiments were done. The high percentage of apoptotic cells was seen in the early apoptosis stage. The expression of Bcl-2 and caspase-8 genes at all doses of laser experienced an obvious reduction in comparison to the control group. On the other hand, although the expression of caspase-9 and caspase-3 genes remains almost constant at 8J/cm², but they faced an increment at 16 and 24J/cm² doses. These data reveal caspase-dependent apoptosis in high and caspase-independent apoptosis in low doses of laser. Based on the results of present work, it can be suggested that the dose of the light source is a key factor in induction of caspase-dependent and caspase-independent apoptosis pathways following PDT.

Novel carbohydrate-substituted metallo-porphyrazine comparison for cancer tissue-type specificity during PDT

A longstanding obstacle to cancer eradication centers on the heterogeneous nature of the tissue that manifests it. Variations between cancer cell resistance profiles often result in a survival percentage following classic therapeutics. As an alternative, photodynamic therapys' (PDT) unique non-specific cell damage mechanism and high degree of application control enables it to potentially deliver an efficient treatment regime to a broad range of heterogeneous tissue types thereby overcoming individual resistance profiles. This study follows on from previous design, characterization and solubility analyses of three novel carbohydrate-ligated zinc-porphyrazine (Zn(II)Pz) derivatives. Here we report on their PDT application potential in the treatment of five common cancer tissue types in vitro. Following analyses of metabolic homeostasis, toxicity and cell death induction, overall Zn(II)Pz-PDT proved comparably efficient between all cancer tissue populations. Differential localization patterns of Zn(II)Pz derivatives between cell types did not appear to influence the overall PDT effect. All cell types exhibited significant disruptions to mitochondrial activity and associated ATP production levels. Toxicity and chromatin structure profiles revealed indiscernible patterns of damage between Zn(II)Pz derivatives and cell type. The subtle differences observed between individual Zn(II)Pz derivatives is most likely due to a combination of carbohydrate moiety characteristics on energy transfer processes and associated dosage optimization requirements per tissue type. Collectively, this indicates that resistance profiles are negated to a significant extent by Zn(II)Pz-PDT making these derivatives attractive candidates for PDT applications across multiple tissue types and subtypes.

Synthesis and photophysicochemical properties of BODIPY dye functionalized gold nanorods for use in antimicrobial photodynamic therapy

A series of boron dipyrromethene (BODIPY) dyes with properties that are ideal for a good photosensitizer have been prepared. Functionalization with bromine atoms and attachment to gold nanoparticles through a meso-aniline group results in high singlet oxygen quantum yields and low fluorescent quantum yields. Molecular modelling was used to analyze trends in the MO energies of various brominated aniline BODIPY dyes.

Iontophoresis Improved Growth Reduction of Invasive Squamous Cell Carcinoma in Topical Photodynamic Therapy

This study examined the potential of iontophoresis in topical photodynamic therapy (PDT) of human invasive squamous cells carcinomas (SCC). SCC was induced in nude BALB/c mice by subcutaneous injection of A431 cells. Tumor penetration and distribution of the photosensitizer tetrasulfonated zinc phthalocyanine (ZnPcS4) was investigated after 10 and 30 min of in vivo iontophoresis of a gel containing ZnPcS4. PDT was performed immediately after iontophoresis using laser at 660 nm with a dose of irradiation of 100 J/cm(2) and irradiance of 48 mW/cm(2) while tumor growth was measured for 30 days. Iontophoresis increased ZnPcS4 penetration into tumors by 6-fold after 30 min when compared with passive delivery. Confocal microscopy analysis showed that ZnPcS4 was homogeneous distributed within deep regions of the tumor after iontophoresis. Irradiation of the tumors immediately after iontophoresis showed reduction in tumor size by more than 2-fold when compared to non-treated tumors. Iontophoretic-PDT treated tumors presented large areas of necrosis. The study concluded that iontophoretic delivery of photosensitizers could be a valuable strategy for topical PDT of invasive SCC.

The effect of ascorbic acid on the photophysical properties and photodynamic therapy activities of zinc phthalocyanine-single walled carbon nanotube conjugate on MCF-7 cancer cells

Zinc mono carboxy phenoxy phthalocyanine (1) was chemical modified with ascorbic acid via an ester bond to give ZnMCPPc-AA (2). Complexes 2 and 1 were coordinated to single walled carbon nanotubes via π-π interaction to give ZnMCPPc-AA-SWCNT (3) and ZnMCPPc-SWCNT (4) respectively. Complexes 2, 3 and 4 showed better photophysical properties: with improved triplet lifetimes and quantum yields, and singlet oxygen quantum yields when compared to 1 alone. The photodynamic therapy activities of complexes 1, 2, 3 and 4 were tested in vitro on MCF-7 breast cancer cells. Ascorbic acid suppresses the photodynamic therapy effect of 1, due to its ability to reduce oxidative DNA damage as a result of its potent reducing properties. The highest phototoxicity was observed for 4 which resulted in 77% decrease in cell viability, followed by 3 which resulted in 67% decrease in cell viability. This shows the importance of combination therapy, where the phthalocyanines are the photodynamic therapy agents and single walled carbon nanotubes are the photothermal therapy agents.

Effect of DTPP-mediated photodynamic therapy on cell morphology, viability, cell cycle, and cytotoxicity in a murine lung adenocarcinoma cell line

Photodynamic therapy (PDT) involves the administration and activation of photosensitizing reagents in cancer tissues to induce cytotoxicity. Here we examined the effects of 5-5- (4-N, N-diacetoxylphenyl)-10,15,20- tetraphenylporphyrin (DTPP) -mediated PDT on cell morphology, viability, cell cycle, and cytotoxicity in a murine lung adenocarcinoma cell line. LA795 murine lung adenocarcinoma cell line was used in the study, with cellular uptake of DTPP being quantified by a UV-visible spectrophotometer. The subcellular localization of DTPP was detected by confocal laser scanning microscopy, alteration of cell morphology after PDT was observed by an inverted light microscope, and late-stage apoptosis was examined by terminal dUTP nick end labeling (TUNEL) . The effects of influencing factors on cytotoxicity of PDT in LA795 cells was investigated with varying concentrations of DTPP, energy densities, power densities, and antioxidants by 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Effects of PDT on cell cycle and plasma membrane integrity were studied by flow cytometry analysis. The uptake of DTPP by LA795 cells reached maximum after incubation for 24 h. Confocal laser scanning microscopy showed that DTPP was mainly in the mitochondrion, and slight localization was detected in the lysosomes. Cellular inhibitory effects increased with increased irradiation dose and DTPP concentration, while unactivated DTPP had low toxicity. Flow cytometry analysis revealed that DTPP-PDT-treated cells showed S phase arrest. Cell membrane damage initiation, repair, and irreversible damage were observed at 2, 4, and 5 h after DTPP-PDT , respectively. Together, our results demonstrated cell apoptosis, compromised viability, and cell cycle S phase arrest of LA795 in response to DTPP-PDT , while no effect on the lung cancer cells was observed with irradiation or photosensitizer treatment alone.

Antitumor activity of photodynamic therapy performed with nanospheres containing zinc-phthalocyanine

BACKGROUND

The increasing incidence of cancer and the search for more effective therapies with minimal collateral effects have prompted studies to find alternative new treatments. Among these, photodynamic therapy (PDT) has been proposed as a very promising new modality in cancer treatment with the lowest rates of side effects, revealing itself to be particularly successful when the photosensitizer is associated with nanoscaled carriers. This study aimed to design and develop a new formulation based on albumin nanospheres containing zinc-phthalocyanine tetrasulfonate (ZnPcS4-AN) for use in the PDT protocol and to investigate its antitumor activity in Swiss albino mice using the Ehrlich solid tumor as an experimental model for breast cancer.

METHODS

Ehrlich tumor's volume, histopathology and morphometry were used to assess the efficacy of intratumoral injection of ZnPcS4-AN in containing tumor aggressiveness and promoting its regression, while the toxicity of possible treatments was assessed by animal weight, morphological analysis of the liver and kidneys, hemogram, and serum levels of total bilirubin, direct bilirubin, indirect bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), alkaline phosphatase, creatinine and urea. In order to evaluate the efficacy of PDT, groups of animals treated with intratumoral injection of doxorubicin (Dox) were also investigated.

RESULTS

Intratumoral injection of ZnPcS4-AN was found to be efficient in mediating PDT to refrain tumor aggressiveness and to induce its regression. Although tumor volume reduction was not significant, PDT induced a remarkable increase in the necrosis area seen in the tumor's central region, as in other experimental groups, including tumor and Dox treated groups, but also in the tumor's peripheral region. Further, PDT showed minimal adverse effects. Indeed, the use of ZnPcS4-AN in mediating PDT revealed anti-neoplastic activity similar to that obtained while using intratumoral Dox therapy.

CONCLUSIONS

PDT mediated by the new formulation ZnPcS4-AN enhanced the inhibition of tumor growth while producing practically no adverse effects and thus emerges as a very promising nanotechnology-based strategy for solid cancer treatment.

Syntheses of near infrared absorbed phthalocyanines to utilize photosensitizers

Phthalocyanines have become of major interest as functional colorants for various applications. In order to use various applications especially photosensitizers, the absorption maxima called Q-band of phthalocyanines are required to be shifted to the near infrared region. Substituted phthalocyanine analog alkylbenzopiridoporphyrazins, especially zinc bis(1,4-didecylbenzo)-bis(3,4-pyrido)porphyrazine, and toroidal-shaped phthalocyanines having aminoamine dendric side chains such as toroidal zinc poly(aminoamine)phthalocyanine dendrons were synthesized. Phthalocyanines of two types reportedly use photosensitizers for photodynamic therapy of cancer. The respective efficacies of photodynamic therapy of cancer for zinc bis(1,4-didecylbenzo)-bis(3,4-pyrido)porphyrazine and its regioisomers were estimated using laser-flash photolysis. The capability of using photodynamic therapy for toroidal zinc poly(aminoamine)phthalocyanine dendrons was assessed using a cancer cell culture. Both phthalocyanines were suitable for the use as a photosensitizer as photodynamic therapy of cancer. Then, non-peripheral thioaryl substituted phthalocyanines, 1,4,8,11,15,18,22,25-octakis(thioaryl)phthalocyanines, such as 1,4,8,11,15,18,22,25-octakis(thiophenylmethyl)phthalocyanines, 1,4,8,11,15,18,22,25-octakis(thiophenylmethoxy)phthalocyanines, and 1,4,8,11,15,18,22,25-octakis(thiophenyl tert-butyl)phthalocyanines were also synthesized in order to develop next- generation photovoltaic cells and/or dye-sensitized solar cells. Non-peripheral substituted 1,4,8,11,15,18,22,25-octakis(thioaryl)phthalocyanines exhibited a Q-band in the near infrared region. Electrochemical measurements were performed on the above-mentioned 1,4,8,11,15,18,22,25-octakis(thioaryl)phthalocyanines described above to examine their electron transfer abilities and electrochemical mechanisms. The compounds 1,4,8,11,15,18,22,25-octakis(thioaryl)phthalocyanines are anticipated to be appropriate materials for use in the next generation of photovoltaic cells.

Development of rapid and highly sensitive HSPA1A promoter-driven luciferase reporter system for assessing oxidative stress associated with low-dose photodynamic therapy

Photodynamic therapy (PDT) is a regulatory-approved modality for treating a variety of malignant tumors. It induces tumor tissue damage via photosensitizer-mediated oxidative cytotoxicity. The heat shock protein 70 (HSP70-1) is a stress protein encoded by the HSPA1A gene and is significantly induced by oxidative stress associated with PDT. The aim of this study was to identify the functional region of the HSPA1A promoter that responds to PDT-induced oxidative stress and uses the stress responsiveness of HSPA1A expression to establish a rapid and cost-effective photocytotoxic assessment bioassay to evaluate the photodynamic potential of photosensitizers. By constructing luciferase vectors with a variety of hspa1a promoter fractions and examining their relative luciferase activity, we demonstrated that the DNA sequence from -218 to +87 of the HSPA1A gene could be used as a functional promoter to detect the PDT-induced oxidative stress. The maximal relative luciferase activity level of HSPA1A (HSP70-1) induced by hypericin-PDT was nearly nine times that of the control. Our results suggest that the novel reporter gene assay using a functional region of the HSP70A1A promoter has significant advantages for the detection of photoactivity in terms of both speed and sensitivity, when compared with a cell viability test based on ATP quantification and ROS levels. Furthermore, phthalocyanine zinc and methylene blue both induced significantly elevated levels of relative luciferase activity in a dose-dependent manner.

Synthesis and evaluation of cationic bacteriochlorin amphiphiles with effective in vitro photodynamic activity against cancer cells at low nanomolar concentration

Bacteriochlorins are attractive candidates as photosensitizers for photodynamic therapy (PDT) due to their intense absorption in the near-infrared (NIR) region of the spectrum where light transmission through tissue is maximal. Many naturally occurring bacteriochlorins are inherently unstable due to adventitious atmospheric oxidation. A de novo synthesis affords bacteriochlorins that contain a geminal dimethyl group in each reduced pyrrole ring to increase stability against oxidation. Here, three new synthetic bacteriochlorins, each bearing a single side-chain containing one or two positive charges, were investigated for their in vitro PDT activity against HeLa human cancer cells. All bacteriochlorins were active at low nanomolar concentration when activated with NIR light; those bearing a single positive charge exhibited faster uptake and higher activity. The bacteriochlorins were localized in mitochondria, lysosomes and endoplasmic reticulum as shown by organelle specific fluorescent probes. Cell death was via apoptosis as shown by cell morphology and nuclear condensation. Taken together, the results show the importance of appropriate peripheral groups about a photosensitizer for effective PDT applications.

Protonation of some non-transition metal phthalocyanines — spectral and photophysicochemical consequences

The photophysics and photochemistry of phthalocyanine complexes of magnesium (MgPc), aluminum chloride (ClAlPc) and zinc (ZnPc) are studied in N,N′-dimethylformamide (DMF). The values obtained for the photophysical and photochemical parameters are normal for simple metallophthalocyanine (MPc) complexes. Protonation of the azomethine bridges reduced the photoactivities of the complexes considerably; however the excited triplet states of the protonated species are more stable towards ground state oxygen. The interaction of the non-protonated MPcs with ground state oxygen is shown to be diffusion-assisted, with bimolecular rate constant values of the order of 1010 M-1.s-1. MgPc could not be protonated; it was easily demetalated by the protonating acid. The kinetics of the demetalation yielded the rate equation: Rate = 0.1[MgPc][H+]2/3

Photodynamic hyperthermal therapy with indocyanine green (ICG) induces apoptosis and cell cycle arrest in B16F10 murine melanoma cells

We examined the effects of photodynamic hyperthemal therapy (PHT), which is a combination of photodynamic therapy (PDT) and hyperthermia (HT), on the apoptosis and cell cycle progression of murine melanoma B16F10 cells. The percentage of apoptotic cell was determined by flow cytometry using fluorescein isothiocyanate (FITC)-conjugated Annexin V and propidium iodide (PI) double staining. The cell cycle analysis was performed by PI staining with flow cytometry. The expression of cyclins and heat shock protein 70 (Hsp70) were examined by a Western blotting analysis. PHT induces death in B16F10 cells, and PHT-mediated apoptosis occurred acutely and persistently in vitro. Our study demonstrated that PHT using indocyanine green (ICG) and near infrared (NIR) light source induces apoptosis and G0/G1 cell cycle arrest in the B16F10 cells.

New hydrophilic/lipophilic tetra-α-(4-carboxyphenoxy) phthalocyanine zinc-mediated photodynamic therapy inhibits the proliferation of human hepatocellular carcinoma Bel-7402 cells by triggering apoptosis and arresting cell cycle

Photodynamic therapy (PDT) is a novel and promising antitumor treatment. Phthalocyanine-mediated PDT has shown antitumor activity in some tumor cells, but the effect of new hydrophilic/lipophilic tetra-α-(4-carboxyphenoxy)phthalocyanine zinc (TαPcZn)-mediated PDT (TαPcZn-PDT) on human hepatocellular carcinoma Bel-7402 cells and underlying mechanisms have not been clarified. In the present study, therefore, the ultraviolet-visible (UV-vis) absorption spectrum and cellular localization of TαPcZn, and effect of TαPcZn-PDT on the proliferation, apoptosis, cell cycle, Bcl-2 and Fas in Bel-7402 cells were investigated by spectrophotometry, inverted microscope, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, electron microscopy, annexinV-FITC/propidium iodide double staining, DNA content and immunoblot assay, respectively. We found that an intense absorption in UV-vis absorption spectrum of TαPcZn was in the red visible region at 650–680 nm, where light penetration in tissue is efficient, that green TαPcZn localized to both plasma membrane and nuclear membrane of Bel-7402 cells, signifying that there was a selective uptake of TαPcZn in Bel-7402 cells and TαPcZn-PDT would be expected to directly damage DNA, and that TαPcZn-PDT significantly resulted in the proliferation inhibition, apoptosis induction, S cell cycle arrest, and down-regulation of Bcl-2 and Fas. Taken together, we conclude that TαPcZn-PDT inhibits the proliferation of Bel-7402 cells by triggering apoptosis and arresting the cell cycle.

Modeling the interactions of phthalocyanines in water: from the Cu(II)-tetrasulphonate to the metal-free phthalocyanine

A quantum and statistical study on the effects of the ions Cu(2+) and SO(3)(-) in the solvent structure around the metal-free phthalocyanine (H(2)Pc) is presented. We developed an ab initio interaction potential for the system CuPc-H(2)O based on quantum chemical calculations and studied its transferability to the H(2)Pc-H(2)O and [CuPc(SO(3))(4)](4-)-H(2)O interactions. The use of the molecular dynamics technique allows the determination of energetic and structural properties of CuPc, H(2)Pc, and [CuPc(SO(3))(4)](4-) in water and the understanding of the keys for the different behaviors of the three phthalocyanine (Pc) derivatives in water. The inclusion of the Cu(2+) cation in the Pc structure reinforces the appearance of two axial water molecules and second-shell water molecules in the solvent structure, whereas the presence of SO(3)(-) anions implies a well defined hydration shell of about eight water molecules around them making the macrocycle soluble in water. Debye-Waller factors for axial water molecules have been obtained in order to examine the potential sensitivity of the extended x-ray absorption fine structure technique to detect the axial water molecules.

Effects of photodynamic therapy using hematoporphyrin monomethyl ether on experimental choroidal neovascularization

Hematoporphyrin monomethyl ether (HMME) is a novel and promising second-generation porphyrin-related photosensitizer for photodynamic therapy (PDT). To study the effects of HMME PDT on choroidal neovascularization (CNV) in rats, the PDT was performed 20 min after HMME bolus injection, which was investigated prior to the PDT by fluorescence microscopy with laser-induced CNV, and delivered at an irradiance of 400, 600 and 1000 mW cm(-2) corresponding to a fluence of 36, 54, 90 J cm(-2) in PDT plan I (15 mg kg(-1) HMME). In PDT plan II (30 mg kg(-1) HMME), the laser had a constant irradiance of 600 mW cm(-2), which was delivered for 60, 90 or 150 s, to also achieve total energy doses of 36, 54 or 90 J cm(-2). CNV closure rates assessed by fluorescein angiography and histologic damage to treated areas of choroid and retina varied as a function of the dose of HMME and of the activating light energy fluence. Endothelial cell labeled by platelet/endothelial cell adhesion molecule-1 presented treated CNV lesions that were significantly reduced in size (P < 0.01). It can be concluded that PDT using HMME can effectively occlude CNV. HMME is a potentially useful photosensitizer for the reduction in CNV size of irradiated areas.

Pentalysine beta-carbonylphthalocyanine zinc: an effective tumor-targeting photosensitizer for photodynamic therapy

Unsymmetrical phthalocyanine derivatives have been widely studied as photosensitizers for photodynamic therapy (PDT), targeting various tumor types. However, the preparation of unsymmetrical phthalocyanines is always a challenge due to the presence of many possible structural isomers. Herein we report a new unsymmetrical zinc phthalocyanine, pentalysine beta-carbonylphthalocyanine zinc (ZnPc-(Lys)(5)), that was prepared in large quantity and high purity. This is a water-soluble cationic photosensitizer and maintains a high quantum yield of singlet oxygen generation similar to that of unsubstituted zinc phthalocyanine (ZnPc). Compared with anionic ZnPc counterparts, ZnPc-(Lys)(5) shows a higher level cellular uptake and 20-fold higher phototoxicity toward tumor cells. Pharmacokinetics and PDT studies of ZnPc-(Lys)(5) in S180 tumor-bearing mice showed a high ratio of tumor versus skin retention and significant tumor inhibition. This new molecular framework will allow synthetic diversity in the number of lysine residues incorporated and will facilitate future QSAR studies.

Apoptotic mechanism of MCF-7 breast cells in vivo and in vitro induced by photodynamic therapy with C-phycocyanin

The aim of this study was to investigate the pro-apoptotic mechanism of C-phycocyanin (C-PC)-mediated photodynamic therapy (PDT) in a murine tumor model and cultured MCF-7 cells. The mice were divided into four groups: control, He-Ne laser radiation, C-PC treatment, and C-PC treatment + He-Ne laser radiation. The effects of C-PC and/or laser on immune organs, immunocyte proliferation, tumor genesis, and apoptosis-related proteins expressions were investigated by immunohistochemistry, in situ hybridization, MTT, electron microscope, western blot, and immunofluorescence assay. The results showed that He-Ne laser treatment alone showed marginal effects. In C-PC-treated mice, the weight of immune organs, proliferation of immunocytes, and expression of pro-apoptotic Fas protein were increased, whereas the tumor weight and the expressions of anti-apoptotic proteins (NF-kappaB and P53) and CD44 mRNA were comparatively decreased. In vitro, C-PC was able to inhibit MCF-7 cell proliferation and cause ultrastructural changes including microvilli loss, formation of membrane blebs, and chromatin condensation. Moreover, C-PC treatment could activate caspase-9 expression, induce cytochrome c release, and downregulate Bcl-2 expression. When combined with He-Ne laser irradiation, the effects of C-PC treatment were further enhanced. Facilitating the apoptosis signals transduction and finally leading to the apoptosis of MCF-7 cells may be the mechanism of the anti-tumor activities of C-PC-mediated PDT.

Intracellular free calcium mediates glioma cell detachment and cytotoxicity after photodynamic therapy

Photofrin photodynamic therapy (PDT) caused a dose-dependent decrease of enzymatic cell detachment by trypsin/ethylenediamine tetra-acetic acid (EDTA) in human glioma U251n and U87 cells. This happened coincidently with the increase of intracellular free calcium ([Ca(2+)](i)). Thapsigargin, which increased [Ca(2+)](i), induced further decrease in enzymatic cell detachment and increased cytotoxicity. Opposite effects were observed when 1,2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetra-acetic acid tetrakis, an intracellular Ca(2+) chelator, was used. PDT-induced changes in [Ca(2+)](i) and cell detachment were not blocked by calcium channel antagonists nickel (Ni(2+)) or nimodipine, nor were they altered when cells were irradiated in a buffer free from Ca(2+) and magnesium (Mg(2+)), suggesting that [Ca(2+)](i) is derived from the internal calcium stores. Decreased cell migration was observed after PDT, as assessed by chemotactic and wound-healing assays. Our findings indicated that internal calcium store-derived [Ca(2+)](i) plays an important role in PDT-induced enzymatic cell detachment decrease and cytotoxicity. Cell migration may be affected by these changes.

Energy transfer in zinc porphyrin-phthalocyanine heterotrimer and heterononamer studied by fluorescence resonance energy transfer (FRET)

Two or eight zinc triphenyl porphyrins were conjugated with Zn-phthalocyanine or H2-phthalocyanine to form ZnPc-(ZnTPP)2, ZnPc-(ZnTPP)8, H2Pc-(ZnTPP)2 and H2Pc-(ZnTPP)8. Energy transfers from the porphyrin moiety to phthalocyanine part were quantitatively studied with the modality of fluorescence resonance energy transfer (FRET). By measuring the fluorescence increment from the phthalocyanine moiety and the decrease from porphyrin part under selective excitation at the B band of the porphyrin part in those conjugated compounds and their equimolar mixture of compositions, energy transfer efficiencies were estimated to be 90% for H2Pc-(ZnTPP)8 and ZnPc-(ZnTPP)8, and 60%, 30% for ZnPc-(ZnTPP)2 and H2Pc-(ZnTPP)2, respectively.

Involvement of mitochondria-caspase pathway in Hemoporfin-mediated cell death

Hemoporfin is a novel second-generation porphyrin-related photosensitizer for ovarian cancer photodynamic treatment (PDT). The purpose of this study was to investigate the molecular mechanisms of Hemoporfin-mediated photocytotoxicity. Human epithelial ovarian cancer cell line 3AO was incubated with different concentrations of Hemoporfin, and phototoxic effects of Hemoporfin on cells were determined using a Cell Viability Analyzer. Apoptosis or necrosis was determined by flow cytometry analysis using the Annexin V-FITC apoptosis kit. Cellular caspase activation was determined using the fluorescent assay kit for caspase-3 and caspase-9. Rhodamine123 was used as a mitochondrial probe and Lucifer Yellow as a lysosomal probe to investigate the intracellular localization of Hemoporfin in 3AO cancer cells. We demonstrated that both high-dose (30 microg mL(-1)) and low-dose (3 microg mL(-1)) Hemoporfin significantly reduced the viability of ovarian cancer cell 3AO with light illumination, and the photocytotoxicity was dose-dependent (P < 0.01). Using a mitochondrial fluorescence probe, we demonstrated a distinct mitochondrial aggregation in 3AO cells with a low concentration of Hemoporfin. Loss of mitochondrial membrane potential was detected as early as 1 h after Hemoporfin-mediated PDT. PDT with low-dose Hemoporfin predominantly induced apoptosis but not necrosis, and both caspase-3 and caspase-9 were activated. Based on our results, mitochondria play an important role in the Hemoporfin-induced apoptosis, and mitochondria membrane potential loss initiated apoptosis via the activation of caspases. Understanding the mechanisms involved in PDT-mediated apoptosis may improve its therapeutic efficacy and facilitate its transition into the clinic.

Interleukin-6 trans signalling enhances photodynamic therapy by modulating cell cycling

Photodynamic therapy (PDT) of solid tumours causes tissue damage that elicits local and systemic inflammation with major involvement of interleukin-6 (IL-6). We have previously reported that PDT-treated cells lose responsiveness to IL-6 cytokines. Therefore, it is unclear whether PDT surviving tumour cells are subject to regulation by IL-6 and whether this regulation could contribute to tumour control by PDT. We demonstrate in epithelial tumour cells that while the action of IL-6 cytokines through their membrane receptors is attenuated, regulation by IL-6 via trans-signalling is established. Soluble interleukin-6 receptor-α (IL-6Rα) (sIL-6Rα) and IL-6 were released by leucocytes in the presence of conditioned medium from PDT-treated tumour cells. Cells that had lost their membrane receptor IL-6Rα due to PDT responded to treatment with the IL-6R–IL-6 complex (Hyper-IL-6) with activation of signal transducers and activator of transcription (STAT3) and ERK. Photodynamic therapy-treated cells, which were maintained during post-PDT recovery in presence of IL-6 or Hyper-IL-6, showed an enhanced suppression of proliferation. Cytokine-dependent inhibition of proliferation correlated with a decrease in cyclin E, CDK2 and Cdc25A, and enhancement of p27kip1 and hypophosphorylated Rb. The IL-6 trans-signalling-mediated attenuation of cell proliferation was also effective in vivo detectable by an improved Colon26 tumour cure by PDT combined with Hyper-IL-6 treatment. Prevention of IL-6 trans-signalling using soluble gp130 reduced curability. The data suggest that the post-PDT tumour milieu contains the necessary components to establish effective IL-6 trans-signalling, thus providing a means for more effective tumour control.

Synthesis and evaluation of cationic phthalocyanine derivatives as potential inhibitors of telomerase

A series of water-soluble cationic phthalocyanine derivatives (1-10) were designed and synthesized to develop novel and potent telomerase inhibitors. These phthalocyanine derivatives as inhibitors of telomerase were investigated via modified telomerase repeat amplification protocol (TRAP) assay. The TRAP assay indicates that these cationic compounds had strong telomerase inhibitory activity (IC(50)<1.65 microM). To determine whether the phthalocyanine derivatives binding to G-quadruplex enhance the block to DNA synthesis, primer extension reactions were carried out in the presence of phthalocyanines. The interaction of the G-quadruplex of telomerase DNA with these molecules was examined by CD melting and PCR stop assay. These cationic phthalocyanine derivatives can stabilize G-quadruplex, which is demonstrated by the increased T(m) values. All these results indicate that the phthalocyanine derivatives might be potential lead compounds for the development of new telomerase inhibitor.

Zinc Phthalocyanine Tetrasulfonate (ZnPcS4): A New Photosensitizer for Photodynamic Therapy in Choroidal Neovascularization

PURPOSE

The aim of this sutdy was to demonstrate the selective localization of a new photosensitizer, zinc phthalocyanine tetrasulfonate (ZnPcS(4)), in rat eyes and investigate the ability of ZnPcS(4) to produce a photochemical closure of experimental choroidal neovascularization (CNV) upon irradiation with a 670-nm laser light.

METHODS

To determine the biodistribution of ZnPcS(4) and the optimal timing of laser irradiation after photosensitizer administration, fluorescence microscopy with ZnPcS(4) was performed. CNV was created in the fundi of Brown-Norway rats using the argon laser model and documented by fluorescein angiography (FFA) and optical coherence tomography (OCT). Photodynamic therapy (PDT) was performed at the dose of 2.0 mg/m(2) and laser fluences of 600 mW/cm(2) on the CNV and on normal retina and choroid. Treatment outcomes were assessed by FFA and OCT and confirmed by light and electron microscopy.

RESULTS

Fluorescence microscopy demonstrated intense ZnPcS(4) fluorescence from the CNV, choriocapillaris, and retinal pigment epithelial cells. Peak ZnPcS(4) intensities in the choriocapillaris and CNV were detected at 10-20 min after an intravenous injection. FFA and OCT indicated that irradiation with 670 nm of laser light 20 min after a ZnPcS(4) injection produced a complete closure of CNV with minimal damage to the overlying retina. Histologic studies, using light and electron microscopy, demonstrated CNV endothelial cell necrosis with minimal damage to the surrounding tissues.

CONCLUSIONS

ZnPcS(4) selectively localizes to the choriocapillaris and CNV in rats, resulting in the occlusion of laser-induced CNV with minimal damage to the retina tissues. ZnPcS(4) -PDT is a potential new strategy for the treatment of macular degeneration and other human diseases manifesting as CNV.

Phase I clinical trial of the use of zinc phthalocyanine tetrasulfonate as a photosensitizer for photodynamic therapy in dogs

OBJECTIVE

To determine the threshold for acute toxicosis of parenterally administered zinc phthalocyanine tetrasulfonate (ZnPcS(4)), a candidate second-generation photosensitizer, in mice and evaluate the compound's safety in a phase I clinical trial of ZnPcS(4)-based photodynamic therapy (PDT) in pet dogs with naturally occurring tumors.

ANIMALS

Male Swiss-Webster mice and client-owned dogs with naturally occurring neoplasms.

PROCEDURES

For the study of acute toxicosis, mice were given graded doses of ZnPcS(4). To determine safety, a rapid-titration phase I clinical trial of ZnPcS(4)-based PDT in tumor-bearing dogs was conducted.

RESULTS

In mice, administration of >or= 100 mg of ZnPcS(4)/kg resulted in renal tubular necrosis 24 hours after IP injection. In tumor-bearing dogs, ZnPcS(4) doses <or= 4 mg/kg induced no signs of toxicosis and resulted in partial to complete tumor responses in 10 of 12 dogs 4 weeks after PDT. Tumor remission was observed with ZnPcS(4) doses as low as 0.25 mg/kg.

CONCLUSIONS AND CLINICAL RELEVANCE

A conservative starting dose of ZnPcS(4) was arrived at on the basis of mouse toxicosis findings. Zinc phthalocyanine tetrasulfonate-based PDT was tolerated well by all dogs and warrants further study. The identification of the maximum tolerated dose through traditional phase I clinical trials may be unnecessary for evaluating novel PDT protocols.

Hypericin-induced photocytotoxicity is connected with G2/M arrest in HT-29 and S-phase arrest in U937 cells

Susceptibility of the HT-29 human colon adenocarcinoma cell line and human myeloid leukemia cell line U937 to hypericin-mediated photocytotoxicity was investigated and compared in this study. Cellular parameters as viability, cell number, metabolic activity and total protein amount were monitored in screening experiments with subsequent cell-cycle analysis and apoptosis detection to determine the cellular response of the different tumor types to various concentrations of photoactivated hypericin. The results show concentration dependence of the photosensitizer's cytotoxicity on the studied cell lines, with higher sensitivity of U937 cells. Whereas the two extreme hypericin concentrations (1 x 10(-9) M and 1 x 10(-6) M) resulted in similar changes in all tested cellular parameters on the two studied cell lines, 1 x 10(-8) M and 1 x 10(-7) M hypericin treatment resulted in different responses of the cell lines in all monitored parameters except for viability. Although leukemic cells proved sensitive to both 1 x 10(-8) M and 1 x 10(-7) M hypericin, significant changes on HT-29 cells were detected only after the 1 x 10(-7) M hypericin concentration. Cell-cycle arrest was related to simultaneously occurring apoptosis in colon cancer. Remarkable is the difference in cell-cycle profile where G2/M arrest in colon cancer cells versus accumulation of leukemic cells in the S phase appears. This suggests that hypericin treatment affecting the cell-cycle machinery of different cancer cells is not universal in effect.