Doxorubicin-loaded PLGA nanoparticles for the chemotherapy of glioblastoma: Towards the pharmaceutical development.

Brain delivery of drugs by nanoparticles is a promising strategy that could open up new possibilities for the chemotherapy of brain tumors. As demonstrated in previous studies, the loading of doxorubicin in poly(lactide-co-glycolide) nanoparticles coated with poloxamer 188 (Dox-PLGA) enabled the brain delivery of this cytostatic that normally cannot penetrate across the blood-brain barrier in free form. The Dox-PLGA nanoparticles produced a very considerable anti-tumor effect against the intracranial 101.8 glioblastoma in rats, thus representing a promising candidate for the chemotherapy of brain tumors that warrants clinical evaluation. The objective of the present study, therefore, was the optimization of the Dox-PLGA formulation and the development of a pilot scale manufacturing process. Optimization of the preparation procedure involved the alteration of the technological parameters such as replacement of the particle stabilizer PVA 30-70 kDa with a presumably safer low molecular mass PVA 9-10 kDa as well as the modification of the external emulsion medium and the homogenization conditions. The optimized procedure enabled an increase of the encapsulation efficiency from 66% to >90% and reduction of the nanoparticle size from 250 nm to 110 nm thus enabling the sterilization by membrane filtration. The pilot scale process was characterized by an excellent reproducibility with very low inter-batch variations. The in vitro hematotoxicity of the nanoparticles was negligible at therapeutically relevant concentrations. The anti-tumor efficacy of the optimized formulation and the ability of the nanoparticles to penetrate into the intracranial tumor and normal brain tissue were confirmed by in vivo experiments.

pH/NIR-responsive semiconducting polymer nanoparticles for highly effective photoacoustic image guided chemo-photothermal synergistic therapy.

Multifunctional drug delivery nanoplatform (PDPP3T@PSNiAA NPs) based on NIR absorbing semiconducting polymer nanoparticles for pH/NIR light-controllably regulated drug release has been successfully prepared. In this strategy, pH/thermal-sensitive multifunctional polymer polystyrene-b-poly(N-isopropylacrylamide-co-acrylic acid) (PSNiAA) was meticulously designed and synthesized using the reversible addition fragmentation chain transfer (RAFT) polymerization method. Furthermore, PSNiAA was used to functionalize diketopyrrolopyrrole-based semiconducting polymer (PDPP3T) to combine photothermal capacity and pH/thermo-responsive drug release in one entity. The prepared PDPP3T@PSNiAA NPs exhibited high photothermal conversion efficiency (η = 34.1%) and excellent photoacoustic (PA) brightness. Meanwhile, benefiting from the photothermal effect of PDPP3T and the pH/thermal-responsive properties of PSNiAA, Dox-loaded PDPP3T@PSNiAA NPs (PDPP3T@PSNiAA-Dox NPs) were able to controllably regulate the release of Dox by pH/NIR light, in which the enhanced drug release at acidic condition upon NIR irradiation phenomenon would minimize unnecessary drug release in normal tissues and was highly beneficial for precise synergistic chemo- and photothermal therapy.

PEGylated doxorubicin cloaked nano-graphene oxide for dual-responsive photochemical therapy.

Graphene oxide (GO) owns huge surface area and high drug loading capacity for aromatic molecules, such as doxorubicin (DOX). However, its biocompatibility is poor and it might agglomerate in physiological conditions. Chemical modification of GO with hydrophilicpolymer, especially PEGylation, was a common method to improve its biocompatibility. But the chemical modification of GO was complicated, and its drug loading capacity might be reduced because of the occupation of its functional groups. In this study, DOX-PEG polymers with different PEG molecular weights were synthesized to modify nano graphene oxide (NGO) to simultaneously realize the solubilization of NGO and the high loading capacity of DOX. The result showed that the drug release of NGO@DOX-PEG was pH sensitive. NIR irradiation could augment the drug release, cellular uptake, cytotoxicity and nuclear translocation of nanodrugs. Among the three kinds of nanodrugs, NGO@DOX-PEG5K was superior to others. It suggested that after conjugating with PEG, the bond between DOX-PEG and NGO was weakened, which resulted in a better drug release and treatment effect. In summary, the NIR and pH dual-responsive NGO@DOX-PEG nanodrugs were developed by noncovalent modification, and it demonstrated excellent biocompatibility and photochemical therapeutic effect, presenting a promising candidate for antitumor therapy, especially NGO@DOX-PEG5K.

Photochemical Activation of Enediyne Warheads: A Potential Tool for Targeted Antitumor Therapy.

Spatial and temporal control over DNA cleavage by photoactivated enediynes can be complemented by additional factors such as the release of internal strain, chelation, pH changes, intramolecular H-bonds, and substituent effects. This review presents design and reactivity of photoactivated enediynes/enynes and analyses the chemical, biological, and photophysical challenges in their applications.

Near infrared light mediated release of doxorubicin using upconversion nanoparticles.

Lanthanide doped upconversion nanoparticles grafted with a photocaged analog of doxorubicin allow near IR-release of doxorubicin.

In vitro localized release of thermosensitive liposomes with ultrasound-induced hyperthermia.

Localized drug delivery with ultrasound-induced hyperthermia can enhance the therapeutic index of chemotherapeutic drugs by improving efficacy and reducing systemic toxicity. A novel in vitro method for the activation of drug-loaded thermosensitive liposomes is described. In particular, a dual-compartment, acoustically transparent container is used in which thermosensitive liposomes suspended in cell culture medium are immersed in a thermally absorptive medium, glycerol. Hyperthermia is induced with ultrasound in the glycerol, which in turn heats the culture medium by thermal conduction. The method approximately mimics the in vivo scenario of thermosensitive liposomes collected in the interstitial spaces of tumors, where ultrasound induces hyperthermia in the tumor tissue, which in turn heats the thermosensitive liposomes by conduction and induces release of the encapsulated drug. The acoustic conditions for the desired hyperthermia are derived theoretically and validated experimentally. Eighty percent release of doxorubicin from thermosensitive liposomes is achieved.

Free radicals generated by tantalum implants antagonize the cytotoxic effect of doxorubicin.

Little is known about the interaction between antineoplastic drugs and implants in bone cancer patients. We investigated the interaction between commercially available porous tantalum (Ta) implants and the chemotherapeutic drug, Doxorubicin (DOX). DOX solutions were prepared in the presence of Ta implant. The changes in fluorescence intensity of the DOX chromophore were measured by spectrofluorometry and the efficacy of DOX was evaluated by viability of rabbit rectal tumor cells (VX2). After 5 min interaction of the DOX solution (5 µg/ml) with the Ta implant, the fluorescent intensity of the DOX solution was 85% degraded, and only 20% the drug efficacy to kill VX2 cells was retained. However, after adding a reducing agent, Dithiothreitol (DTT, 10 µg/ml), 80% of the original fluorescence and 50% of the drug efficacy were restored while UV irradiation enhanced drug degradation in the presence of Ta implant. The action of DTT and UV irradiation indicated that reactive oxygen species (ROS) were involved in the drug degradation mechanism. We detected that Ta implants in aqueous medium produced hydroxyl radicals. Cells showed higher intracellular ROS activity when culture medium was incubated with the Ta implant prior to cell culture. It is concluded that the porous Ta implant antagonizes the cytotoxicity of DOX via ROS generation of the porous Ta implant.

A novel Doxorubicin prodrug with controllable photolysis activation for cancer chemotherapy.

PURPOSE: Doxorubicin (DOX) is a very effective anticancer agent. However, in its pure form, its application is limited by significant cardiotoxic side effects. The purpose of this study was to develop a controllably activatable chemotherapy prodrug of DOX created by blocking its free amine group with a biotinylated photocleavable blocking group (PCB). METHODS: An n-hydroxy succunamide protecting group on the PCB allowed selective binding at the DOX active amine group. The PCB included an ortho-nitrophenyl group for photo cleavability and a water-soluble glycol spacer arm ending in a biotin group for enhanced membrane interaction. RESULTS: This novel DOX-PCB prodrug had a 200-fold decrease in cytotoxicity compared to free DOX and could release active DOX upon exposure to UV light at 350 nm. Unlike DOX, DOX-PCB stayed in the cell cytoplasm, did not enter the nucleus, and did not stain the exposed DNA during mitosis. Human liver microsome incubation with DOX-PCB indicated stability against liver metabolic breakdown. CONCLUSIONS: The development of the DOX-PCB prodrug demonstrates the possibility of using light as a method of prodrug activation in deep internal tissues without relying on inherent physical or biochemical differences between the tumor and healthy tissue for use as the trigger.

Effect of gamma irradiation on spleen cell function and cytotoxicity of doxorubicin.

The present study was attempted to evaluate the effects of gamma-irradiated doxorubicin (IRD) on spleen cell proliferation, cytokines release (IFN-gamma and IL-2) and lung metastasis in mice. Gamma irradiation induced degradation of doxorubicin molecule and cytotoxicity on melanoma (B16BL6) and myoblast (H9c2) cell lines were determined by high performance liquid chromatography (HPLC) and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazole) assay, respectively. Non-irradiated doxorubicin (NIRD) was used as a control. The mice injected with NIRD (2mg/kg body weight for 5 days, 24h interval) showed a considerable decrease (P<0.05) in the body, spleen weight, proliferation and cytokine release (IL-2 and IFN-gamma) as compared to control. However, a non-significant variation was observed in IRD treated mice compared with normal. Tumor bearing mice treated with NIRD and IRD (2mg/kg body weight, five doses at 48 h interval) showed diverse results on spleen cell cytokine release, proliferation and metastasis. HPLC results revealed the formation of several trace level degradation (P<0.05) products of IRD. IRD displayed a non-significant variation of cytotoxicity on B16BL6 cells, and low percentage (P<0.01) of cardiotoxicity on H9c2 cells as compared to NIRD. Altogether, this present study emphasis that gamma irradiation altered the property of doxorubicin.

Photoexcited calphostin C selectively destroys nuclear lamin B1 in neoplastic human and rat cells - a novel mechanism of action of a photodynamic tumor therapy agent.

Lamin B1, a major component of the nuclear lamina, anchors the nucleus to the cytoskeletal cage, and controls nuclear orientation, chromosome positioning and, alongside several enzymes, fundamental nuclear functions. Exposing polyomavirus-transformed rat pyF111 fibroblasts and human cervical carcinoma (HCC) C4-I cells for 30 min to photoexcited perylenequinone calphostin C, i.e. Cal C(phiE), an established reactive oxygen species (ROS)-generator and protein kinase C (PKC) inhibitor, caused the cells to selectively oxidize and then totally destroy their nuclear lamin B1 by only 60 min after starting the treatment, i.e. when apoptotic caspases' activities had not yet increased. However, while the oxidized lamin B1 was being destroyed, lamins A/C, the lamin A-associated nuclear envelope protein emerin, and the nucleoplasmic protein cyclin E were neither oxidized nor destroyed. The oxidized lamin B was ubiquitinated and demolished in the proteasome probably by an enhanced peptidyl-glutaminase-like activity. Hence, the Cal C(phiE)-induced rapid and selective lamin B1 oxidation and proteasomal destruction ahead of the activation of apoptotic caspases was by itself a most severe molecular lesion impairing vital nuclear functions. Conversely, Cal C directly added to the cells kept in the dark damaged neither nuclear lamin B1 nor cell viability. Thus, our findings reveal a novel cell-damaging mechanism of a photodynamic tumor therapeutic agent.

Radiation sterilisation of doxorubicin bound to poly(butyl cyanoacrylate) nanoparticles.

Doxorubicin-loaded poly(butyl cyanoacrylate) (PBCA) nanoparticles were prepared by anionic polymerisation under non-aseptic conditions. The feasibility of sterilisation of this formulation using either gamma-irradiation or electron beam irradiation was investigated. The irradiation doses ranged from 10 to 35 kGy. Bacillus pumilus was used as the official test microorganism. The bioburden of the untreated formulation was found to be 100 CFU/g. Microbiological monitoring revealed that at this level of the bioburden the irradiation dose of 15 kGy was sufficient for sterilisation of the nanoparticles. The formulation showed excellent stability with both types of irradiation in the investigated dose range. The irradiation did not influence the physicochemical parameters of the drug-loaded and empty nanoparticles, such as the mean particle size, polydispersity, and aggregation stability. The molecular weights of the PBCA polymer as well as the polydispersity indices (M(w)/M(n)) remained nearly unchanged. The drug substance was stable to radiolysis. Additionally, the presence of irradiation-induced radicals was evaluated by ESR spectroscopy after storage of the particles at ambient temperature. The paramagnetic species found in the formulation were mainly produced by irradiation of mannitol and dextran used as excipients.

Effects of extremely low-frequency electromagnetic fields on delayed chromosomal instability induced by bleomycin in normal human fibroblast cells.

This study was carried out to examine the interaction of extremely low-frequency electromagnetic fields (ELF-EMF) on delayed chromosomal instability by bleomycin (BLM) in human fibroblast cells. A micronucleus-centromere assay using DNA probes for chromosomes 1 and 4 was performed and a 60-Hz ELF-EMF of 0.8 mT field strength was applied either alone or with BLM throughout the culture period. The frequencies of micronuclei (MN) and aneuploidy were analyzed at 28, 88, and 240 h after treatment with BLM. The coexposure of cells to BLM and ELF-EMF led to a significant increase in the frequencies of MN and aneuploidy compared to the cells treated with BLM alone. No difference was observed between field-exposed and sham-exposed control cells. The frequency of MN induced by BLM was increased at 28 h, and further analysis showed a persistent increase up to 240 h, but the new levels were not significantly different from the level at 28 h. BLM increased the frequencies of aneuploidy at 28, 88, and 240 h, and significantly higher frequency of aneuploidy was observed in the cells analyzed at 240 h compared to the cells examined at 28 h. No interaction of ELF-EMF on delayed chromosomal instability by BLM was observed. Our results suggest that ELF-EMF enhances the cytotoxicity of BLM. BLM might induce delayed chromosomal instability, but no effect of ELF-EMF was observed on the BLM-induced delayed chromosomal instability in fibroblast cells.

A novel concept to activate enediynes for DNA cleavage.

A novel concept is presented to activate enediynes via a biscumulenic intermediate using photoinduced electron transfer (PET).

The riboflavin-mediated photooxidation of doxorubicin.

PURPOSE: Previously, it was shown that exposing doxorubicin (ADR) to 365 nm light resulted in the loss of its cytotoxic activity as well as its absorbance at 480 nm. These processes were much enhanced when mediated by riboflavin. In the present study we investigated the quantitative and qualitative aspects of riboflavin-mediated photodegradation of ADR. METHODS: ADR solutions containing variable concentrations of riboflavin and other agents were exposed to 365 nm light for variable time periods and then the absorbance spectrum of ADR was measured by a double beam spectrophotometer. These measurements were used to calculate the half-time of the ADR degradation process. The degraded ADR solutions were analyzed by chromatography and mass spectrometry. RESULTS: Analysis of the riboflavin effect indicated that a maximal rate of photolytic degradation of ADR was obtained only after most of the ADR molecules had formed bimolecular complexes with riboflavin. The retardation of lumichrome formation by ADR and the inhibition of ADR bleaching by excess of ascorbic acid suggested that ADR was degraded by a photooxidation process. Similar spectral changes occurred when ADR was exposed to strong oxidizers such as sodium hypochlorite and dipotassium hexachloroiridate. Cyclic voltammetry revealed that the oxidation-reduction process of ADR was not electrochemically reversible and therefore the oxidation potential could not be determined accurately; however its value should be between 0.23 and 0.78 V. Analysis of the photooxidative process revealed that it was not mediated by the formation of singlet oxygen, superoxide anion radicals, hydrogen peroxide or hydroxyl radicals, and it is suggested that ADR was oxidized directly by the excited triplet riboflavin. The mass spectrograms and the HPLC chromatograms of photooxidized ADR indicate that the central ring of ADR was opened and that 3-methoxysalicylic acid was produced by this cleavage. CONCLUSIONS: The riboflavin-mediated photodegradation of ADR is an oxidative process resulting in the cleavage of the anthraquinone moiety. 3-Methoxysalicylic acid was identified as one of the resulting fragments. It is possible that some of the large fractions of the ADR metabolites that are non-fluorescent are the result of an in vivo oxidation of ADR and that 3-methoxysalicylic acid may play a role in the different biological activities of ADR.

Laser chemotherapy of human carcinoma cells with three new anticancer drugs.

A new experimental therapy for squamous carcinoma was tested by sensitizing human tumor cells with light-sensitive anticancer drugs followed by laser illumination at visible or infrared wavelengths. The anthrapyrazole DUP-941 and the isoquinoline derivative DUP-840 were compared with the dianthraquinone hypericin. P3 human squamous carcinoma cells were incubated for 2 h with the drugs at escalating doses ranging from 5 to 100 micrograms/ml, then exposed to visible green 532-nm or infrared 1064-nm light at 300 J output from a KTP/Nd:YAG laser. Tumor cell toxicity measured by in vitro MTT viability assays was minimal after DUP-840 uptake but was slightly enhanced by infrared laser emissions. By contrast, the strong tumoricidal effects seen after DUP-941 uptake were amplified over 10-fold by 532-nm light and up to 2-fold by 1064-nm light. Hypericin-sensitized tumor cells were killed after 532 nm irradiation even at the lowest drug dose but were not affected by 1064-nm illumination. The results suggest that laser chemotherapy with drugs sensitive to photothermal energy could become a useful new treatment modality for cancer.

The inactivation of doxorubicin by long ultraviolet light.

PURPOSE: Irradiation of doxorubicin (DOX) dissolved in RPMI medium 1640 by long ultraviolet (UVA) light results in a rapid decline in the cytotoxic activity of the drug. The present study was designed to sort out which component(s) of this medium are associated with the UVA inactivation of DOX. METHODS: The effects of UVA irradiation of DOX in solutions of various compositions were evaluated by measuring the changes in the drug growth inhibitory activity in P388 cells and in the DOX absorbance spectrum. RESULTS: Riboflavin seemed to be the major photosensitizing component in the medium and the effect was enhanced by the presence of histidine, methionine, tryptophan and tyrosine but not by other amino acids. The changes in DOX resulting from UVA irradiation in the presence of riboflavin, were not blocked by 1,4-diazabicyclo [2.2.2]octane (5 mM), superoxide dismutase (300 units/ml), catalase (150 units/ml) or sodium benzoate (50 mM). The effects of UVA light on doxorubicin could be prevented by excess ascorbic acid. CONCLUSIONS: The effects of UVA on DOX are mediated by riboflavin. The photoexcited riboflavin apparently interacts directly with DOX rather than by first forming reactive oxygen species. The results suggest that the photoinactivation of DOX may involve an oxidation step. The mechanism by which certain amino acids facilitate the photoinactivation of DOX is not known. It is suggested that patient intake of riboflavin and exposure to the sun and fluorescent light could affect the outcome of anthracycline treatment.

A comparative study of the visible light photochemistry of gilvocarcins V and M.

Quantum yields for the formation of superoxide ions, O2-., and singlet oxygen, 1O2, were determined during the photolyses of gilvocarcin M (GM) in air-saturated dry dimethylsulfoxide (DMSO) and in 45:55 (vol/vol) DMSO-water mixtures. The quantum yield for the photoreduction of methyl viologen by GM in nitrogen-saturated dry DMSO was also determined. These values are not different, within experimental error, from those corresponding to gilvocarcin V (GV). Because GV is a strong photocytotoxic agent and GM is not, these results imply that Type I and Type II mechanisms are not important pathways in the cytotoxicity of GV.

Gilvocarcin V exhibits both equilibrium DNA binding and UV light induced DNA adduct formation which is sequence context dependent.

The relative degree of both equilibrium binding and of ultraviolet light induced adduct formation for the antitumor antibiotic gilvocarin V with two hexaecamer DNA sequence isomers, d[ATATATAGCTATATAT]2 and d[AAAAAAAGCTTTTTTT]2, was assessed. The experiments reveal that gilvocarin V binds, under equilibrium conditions, and reacts, in the presence of exogenously applied UV light, more efficiently with the alternating purine:pyrimidine sequence hexadecamer than the homopurine:homopyrimidine duplex at identical gilvocarcin V to DNA duplex ratios. DNAse I digests of adduct containing duplexes derived from the d[AAAAAAAGCTTTTTTT]2 duplex, identified and isolated using gel shift assays employing denaturing polyacrylamide gels, confirm that gilvocarcin V adducts can be formed with thymine residues but suggest that adduct formation with either adenine or guanine residues is also possible.

Aminopeptidase activity of an antitumor antibiotic, C-1027.

An antitumor antibiotic C-1027, a complex protein consisting of an apoprotein and a non-covalently bound chromophore, showed some aminopeptidase activity, 1/15 (on the basis of activity per mg protein) that of porcine kidney enzyme [E.C. 3.4.11.2] by use of L-phenylalanyl 4-methyl-coumaryl-7-amide as the substrate. Neither the apoprotein alone nor the chromophore alone were active. Amastatin and bestatin but not leupeptin inhibited the activity. The enzyme activity of the holo-antibiotic, as opposed to that of the porcine kidney enzyme, was readily lost by UV irradiation, indicating that the intact structure of the chromophore was needed to maintain the native conformation of the holo-antibiotic. The cytotoxicity of the holo-antibiotic, but not that of the chromophore, to Ehrlich carcinoma cells in vitro was reduced to 1/5 by 1 microgram/ml of amastatin which alone had no effect on cell growth. The porcine aminopeptidase was not cytotoxic at all even at higher concentrations (higher enzyme activities/ml). Amastatin possibly occupied the catalytic domain of the holo-antibiotic, interfering with the binding of the holo-antibiotic with some cell-surface protein(s). Amastatin did not inhibit the holo-antibiotic to cleave isolated DNA.

An ESR study of the visible light photochemistry of gilvocarcin V.

Photolysis of gilvocarcin (GV) at 405 nm in argon saturated dimethylsulfoxide (DMSO) or 50% DMSO-water solutions in the presence of the sodium salt of 3,5-dibromo-2,6-dideutero-4-nitrosobenzene sulfonic acid (DBNBS-d2) generates the CH3-DBNBS-d2.spin adduct. It is postulated that this spin adduct is produced by photoreduction of DMSO by GV and the consequent formation and trapping of the generated methyl radicals. Gilvocarcin V also photoreduces oxygen and methyl viologen with quantum yields of 0.019 and 0.0012 respectively. The quantum yield for singlet oxygen formation by GV in DMSO, determined by measuring the rate of production of the nitroxyl radical produced by the reaction of 2,2,6,6-tetramethylpiperidinol with singlet oxygen, was found to be 0.15. Thus, GV photochemistry proceeds by both Type I and Type II pathways which could contribute to the reported GV phototoxicity in biological systems.