Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.2 (focal adhesion kinase)
 44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitroimidazoles are good quenchers of triplet state porphyrins in chemical systems, thereby inhibiting singlet oxygen formation and type II photodynamic reactions. Photobiological studies were performed with EMT-6 tumor cells in vitro utilizing Photofrin II (PII) in combination with etanidazole (ETAN), misonidazole (MISO), and trifluoromisonidazole (TF-MISO). After short-term (1 h) exposure of cells to PII, 5 mM ETAN and MISO had no effect on photoinactivation while 5 mM TF-MISO had a small but significant protective effect. When the intracellular oxygen level was equilibrated with 0.3% oxygen in the gas phase, all three nitroimidazoles produced significant photoprotection at concentrations as low as 0.3 microM. After long-term (24 h) exposure of cells to PII, all three nitroimidazoles demonstrated large photoprotective effects under both aerobic and 0.3% oxygen conditions. At equal concentrations of nitroimidazole, photoprotection was greatest for the most lipophilic compound (TF-MISO) and least effective for the most hydrophilic compound (ETAN). These studies suggest that nitroimidazoles can quench triplet state porphyrins (within cells) to reduce intracellular concentrations of singlet oxygen, the putative toxin in PII photoinactivation. In addition, after long-term exposures to PII when porphyrins have partitioned into cellular membranes and lipid environments, the lipophilicity of this class of photoprotector correlates with effectiveness in these mammalian cells.
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PMID:Protection against light-activated photofrin II killing of tumor cells by nitroimidazoles. 153 56

Asynchronous populations of mouse EMT-6 tumor cells were treated with Photofrin II and exposed to various doses of 630 nm light in slowly stirred suspensions which had been equilibrated with various concentrations of oxygen. Survival curves were generated with cells exposed to 20 micrograms/ml Photofrin II in tissue culture medium for 1 h, a procedure which made it possible to remove more than 50% of the drug by washing. It is expected that under these conditions the drug would be loosely bound to cell surface and plasma membranes and in the cellular cytosol. Survival curves were also generated with cells exposed to 5 micrograms/ml Photofrin II for 20-24 h, a procedure which resulted in greater than 90% of the drug being tightly bound within cells, presumably to cellular lipids and membranes. Oxygen was obligatory for killing cells which had been exposed for both "short term" and "long term" to Photofrin II. After 30-40 min of pregassing cells with nitrogen gas which contained precise levels of oxygen, the concentration required to reduce rates of cell killing to 50% of maximum was approximately 0.5% O2 (gas phase) for short-term drug exposures and less than or equal to 0.05% O2 for long-term drug exposures. Even after pregassing times of 90-120 min prior to light administration, a Km of approximately equal to 0.1% O2 was observed for cells exposed to the drug for the longer time. When the same cells were exposed to 137Cs gamma rays in this irradiation chamber, no change in radiation sensitivity was observed after 30 min of pregassing cells with all oxygen concentrations studied.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oxygen dependency of tumor cell killing in vitro by light-activated Photofrin II. 182 59

Asynchronous populations of mouse EMT-6 tumor cells were exposed to various doses of 630-nm light in slowly stirred aerobic suspensions after both short-term and long-term exposures to Photofrin II. All survival curves are characterized by a "threshold" light dose below which no cell inactivation occurs followed by a steep light-dose response. Both the shoulder widths and the inactivation curve slopes are functions of Photofrin II concentration. After high doses of light where survival levels are 0.003 and lower, "resistant tails" are observed on some survival curves. Light doses required to inactivate 50% of tumor cell populations were obtained from whole survival curves and their reciprocals (1/D50% survival) used as inactivation "rates". The amount of Photofrin II within cells was measured by a fluorescence assay. Per unit of fluorescence, this photosensitizer is at least 10 times more effective after long-term than after short-term exposures. After long-term exposures, both fluorescence activity and photosensitizing effectiveness are retained in washed cells for several hours. After short-term exposures, a majority of both the fluorescence and photosensitizing activity is lost by multiple washings or stirring in tissue culture medium without drug. These data suggest that the cellular compartments associated with photosensitization after short-term exposures to Photofrin II are probably different from the cellular compartments associated with photosensitization after long-term exposures to the drug. The data are consistent with known properties of the monomeric and oligomeric components of Photofrin II.
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PMID:The effectiveness of short-term versus long-term exposures to Photofrin II in killing light-activated tumor cells. 183 85

Several studies have examined the synergism of hyperthermia or chemotherapy agents in combination with photodynamic therapy (PDT) to enhance tumor eradication. In our unique approach to treatment, multiple photosensitizers and wavelengths were used: two photosensitizers, Photofrin II and meso-tetra-(4-sulfonatophenyl)-porphine (TPPS4), irradiated at the appropriate therapeutic wavelength for each photosensitizer. EMT-6 mammary tumors were induced in the flanks of BALB/c mice. The mice were assigned to a control group (50 mice) or treatment group (150 mice). All treatment animals and some control animals received photosensitizing drug (5 mg/kg of TPPS4, 5 mg/kg of Photofrin II, or 2.5 mg/kg of both TPPS4 and Photofrin II). All treatment animals and some control animals also received light treatment (630 nm for TPPS4 and/or 658 nm for Photofrin II). The results show that the approach using both drugs and the corresponding therapeutic wavelengths enhanced the effectiveness of PDT. This approach achieved a cure rate of up to 100%, which was, depending on the light intensity used, as much as 40% greater than the rate achieved by the approach using one drug and one wavelength. The results also show that lesser amounts of drug and/or light may be required if both drugs and wavelengths are used, thus lowering the chances of side effects common to PDT. Furthermore, the results indicate that the increased tumor kill is due to a synergistic effect of the two photosensitizers that was tested on the tumor microvasculature in the first few hours after PDT.
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PMID:Use of multiple photosensitizers and wavelengths during photodynamic therapy: a new approach to enhance tumor eradication. 213 4

The in vivo biological activity of uroporphyrin I has been studied by determining the amount of necrosis produced in murine tumors exposed to various total doses of light at 615 nm. Similarly, the in vitro photosensitizing activity of uroporphyrin I was examined by measuring the percentage of cells killed in a cell culture system. Light doses used were 25-400 J/cm2. Mice that received uroporphyrin I at 40 mg/kg had only minimal superficial necrosis upon histological examination at doses of 400 J/cm2 (615 nm). Those tumors that received 300 J/cm2 or less showed no histological evidence of necrosis. Mice that received hematoporphyrin derivative (Photofrin II) at 10 mg/kg were completely necrotic at total doses of 100 J/cm2 (630 nm). PTK2 epithelial cells incubated with uroporphyrin I at either 40 micrograms/ml or 80 mu/ml and 10 J/cm2 (615 nm) showed no apparent damage and had 100% cell survival. By contrast, those cells treated with hematoporphyrin derivative (Photofrin II) at 25 micrograms/ml and 10 J/cm2 (630 nm) exhibited 100% cell kill. It is concluded that uroporphyrin I is a poor photosensitizer in both in vivo and in vitro systems compared to hematoporphyrin derivative (Photofrin II).
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PMID:Study of the in vivo and in vitro photosensitizing capabilities of uroporphyrin I compared to photofrin II. 294 30

Structural modifications to the photoinactive benzophenoxazine Nile blue A have led to three novel derivatives which include 5-ethylamino-9-diethylaminobenzo[a]phenoxazinium (EtNBA), 5-ethylamino-9-diethylaminobenzo[a]phenothiazinium (EtNBS), and 5-ethylamino-9-diethylaminobenzo[a]phenoselenazinium (EtNBSe) chlorides. The incorporation of sulfur and selenium into the benzophenoxazine moiety results in lipophilic, red-absorbing (650-660 nm) chromophores which possess significantly increased singlet oxygen yields (0.025 and 0.65, respectively, compared to 0.005 for EtNBA). This study examines the photosensitizing efficacies and pharmacokinetics in vitro in the EMT-6 murine mammary sarcoma cell line as well as the physicochemical, photochemical, and redox properties of these new analogues. Comparisons with Photofrin II, the only photosensitizer available clinically, were made in an attempt to high-light their different pharmacological characteristics. The photodynamic activity of the benzophenoxazine dyes correlates with their ability to generate the phototoxin singlet oxygen and increases in the following order: EtNBA < EtNBS << EtNBSe. At an extracellular dye concentration of 0.5 microM, the light dose required to kill approximately 50% of the cells was 2.0 and < 0.5 J/cm2 for the sulfur and selenium dyes, respectively. The light dose required to kill approximately 50% of the cells for both EtNBA and Photofrin II could not be determined because of their weak phototoxic effect under these conditions. At a light dose of 3.3 J/cm2, EtNBSe is approximately 1000 times more phototoxic than Photofrin II. All three benzophenoxazine derivatives are characterized by a similar uptake/efflux pattern in vitro consisting of a rapid and extensive cellular accumulation followed by a slow efflux rate. Contrary to their rapid uptake, 50% of the accumulated EtNBS and EtNBSe is retained intracellularly after a 6-h period in dye-free medium. Video-enhanced fluorescence microscopy corroborates the rapid uptake measurements as well as indicating the intracellular localization of the dyes in both living and thermally inactivated cells. Low extracellular dye concentrations (0.05 microM) result in a punctate fluorescence pattern in the perinuclear region, while higher dye concentrations (> 0.1 microM) lead to additional fluorescence in the cytoplasm, cytomembranes, and other organelles but apparently not the nucleus. Absorption spectrometry revealed that living cells rapidly reduce the dyes to their colorless leuko form (photoinactive) if oxygen is not readily available in the environment. It is shown that the cellular reduction is an enzymatic process and that an oxygen-free and cell-free medium containing both the coenzyme NADH and the hydride transfer enzyme diaphorase is capable of reducing the dyes to the colorless leuko form.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Phototoxicity, redox behavior, and pharmacokinetics of benzophenoxazine analogues in EMT-6 murine sarcoma cells. 849 21

The influence of the calcium channel blocker verapamil on the sensitivity of mouse fibrosarcoma cells of the line EMT-6 to treatment with Photofrin II (PII) or tetra(4-sulfonatophenyl)porphine (TPPS4) and light has been assessed. Cells were treated with 1.5 microg/ml PII or 75 microg/ml TPPS4 overnight in the absence or presence of 50 microg/ml verapamil and subsequently exposed to light. Verapamil increased the sensitivity of the EMT-6 cells to PII-induced photoinactivation by a factor of 2. In contrast, verapamil decreased the sensitivity of the cells to TPPS4-induced photoinactivation by 50-60%. Both sensitizers were found to be located to a large extent in lysosomes as revealed by fluorescence microscopy and by photochemical inactivation of the lysosomal marker enzyme beta-N-acetyl-D-glucosaminidase. Verapamil increased the uptake of PII by 30% and reduced the uptake of TPPS4 by 20%. Furthermore, verapamil enhanced the binding and uptake of LDL by about 40%. In conclusion, the effects of verapamil-induced sensitization of EMT-6 cells treated with PII or TPPS4 and light can to a large extent be attributed to the modulatory effects of verapamil on endocytosis.
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PMID:Verapamil enhances the uptake and the photocytotoxic effect of PII, but not that of tetra(4-sulfonatophenyl)porphine. 954 91

Pretreatment of EMT-6 murine tumor cells for 24 h with 10(-4) M 8-methoxypsoralen (8-MOP) increased the photocytotoxicity of Photofrin II (P2) after cell exposure to low doses (1-1.5 J/cm2) of UVA by two- to three-fold. 8-MOP alone had no cytotoxic action under these experimental conditions and did not significantly change the amount of P2 recovered in cells. 8-MOP enhanced the lipid peroxidation end product formation measured as thiobarbituric acid reactive substances (TBARS) during cell photosensitization by P2. The psoralen alone also slightly increased the TBARS level after UVA exposure. These results suggest that 8-MOP, albeit non-photocytotoxic by itself under our experimental conditions, could enhance the efficiency of P2 by increasing cellular lipid peroxidation following light exposure.
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PMID:8-Methoxypsoralen potentiates the photocytotoxic effect of Photofrin II towards EMT-6 murine tumor cells. 968 80

Tolyporphin (TP), a porphyrin extracted from cyanobacteria, was found to be a very potent photosensitizer of EMT-6 tumor cells grown both in vitro as suspensions or monolayers and in vivo in tumors implanted on the backs of C.B17/Icr severe combined immunodeficient mice. Thus, during photodynamic treatment (PDT) of EMT-6 tumor cells in vitro, the photokilling effectiveness of TP measured as the product of the reciprocal of D50 (the light dose necessary to kill 50% of cells) and the concentration of TP is approximately 5000 times higher than that of Photofrin II (PII), the only PDT photosensitizer thus far approved for clinical trials. TP almost exclusively localizes in the perinuclear region and specifically in the endoplasmic reticulum (ER), as shown by microspectrofluorometry on single living EMT-6 cells costained with the ER and/or Golgi fluorescent vital probes, 3,3'-dihexyloxacarbocyanine iodide and N-[4,4-difluoro-(5,7-dimethyl-BODIPY)-1-pentanoyl]-D-erythro-sphin gosine (Molecular Probes, Eugene, OR). As a result, the singlet oxygen-mediated photodynamic activity of TP induces an effective inactivation of the acyl CoA:cholesterol-O-acyltransferase, a sensitive marker of ER membrane integrity and alterations of the nuclear membrane. In vivo, with the EMT-6 mouse tumor model, an exceptional effectiveness is also observed as compared to that of PII and other second generation photosensitizers of the pheophorbide class, which are themselves much more potent than PII. The outstanding PDT activity of TP observed in vivo may be due to its unique biodistribution properties, in particular much less extraction by the liver, resulting in a higher delivery to other tissues, including tumor.
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PMID:Tolyporphin: a natural product from cyanobacteria with potent photosensitizing activity against tumor cells in vitro and in vivo. 972 63