Growth Cycle‐Dependent Overproduction and Accumulation of Protoporphyrin IX in Tetrahymena: Effect of Heavy Metals1
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ABSTRACT Cells of the ciliate Tetrahymena pyriformis GL overproduce and accumulate massive quantities of the heme intermediate, protoporphyrin IX. Protoporphyrin is localized intracellularly in discrete membranous compartments. The amount of porphyrin stored in the cell changes dramatically as cells progress through the growth cycle. Porphyrin overproduction is stimulated by δ‐aminolevulinic acid, but only during the mid‐stationary phase. Overproduction of protoporphyrin IX apparently results from an increase, late in the growth cycle, of activities subsequent to δ‐aminolevulinic acid synthetase. Feedback inhibition in the pathway by accumulated protoporphyrin IX does not occur. The presence of Co 2+ completely inhibits accumulation of protoporphyrin IX in a manner reversed by δ‐aminolevulinic acid. Sn 4+ stimulates protoporphyrin IX accumulation in the culture.Keywords:
Protoporphyrin IX
Overproduction
Tetrahymena pyriformis
Hematoporphyrin
Abstract The photosensitizing activities of hematoporphyrin, Cu‐hematoporphyrin, protoporphyrin. Zn‐protoporphyrin, deuteroporphyrin and uroporphyrin are studied. The relative yields of 1 O 2 are measured in buffer (pH 8.0) and compared to the yields of Type II photodamages induced on cholesterol embedded in egg lecithin liposomes. Results show that the solubilization of the sensitizer in the lipid bilayer is a prerequisite for its photosensitizing activity at the membrane level. In this context, the partition coefficient represents an important parameter.
Hematoporphyrin
Phototoxicity
Egg lecithin
Hemin
Protoporphyrin IX
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In vivo fluorescence studies of Cyanidium caldarium mutants grown in the dark in dextrose-containing media have shown that these organisms accumulate protoporphyrin IX. In the dark the accumulated protoporphyrin IX is gradually turned into a metalloporphyrin, Zn protoporphyrin. In the light, in the chlorophyll-lacking mutant GGB, both compounds are degraded and phycobiliproteins are formed. These results implicate protoporphyrin IX in situ as the general precursor to tetrapyrrole pigments and Zn protoporphyrin IX as a possible intermediate or regulator in the biosynthesis of phycobilins.
Protoporphyrin IX
Tetrapyrrole
Phycobiliprotein
Protochlorophyllide
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The effectiveness of hematin and protoporphyrin IX as photosensitizers in singlet oxygen(1O2)generation was determined and at the same time the influence of different light wavelength on them was studied. The results revealed protoporphyrin IX showed stronger photosensitizing activity than hematin in singlet oxygen generation. The light intensity above 430lux activated protoporphyrin IX and the light intensity above 630lux activated hematin in accelerating lipid oxidation. And the stronger the intensity, the stronger the activated function.
Protoporphyrin IX
Light intensity
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[Objective] To explore the characteristics of cumulation of protoporphyrin Ⅸ in SW480 cells induced by DFO and 5-ALA. [Method] SW480 cells were respectively cultivated in 4 groups, Group A, B, C, D, using culture solution, RPMI1640 with DFO 0.1 mmol/mL, 0.1 mmol/mL DFO + 2 mmol/mL 5-ALA, 5-ALA 2 mmol/mL, without DFO, 5-ALA for 10 hr. Fluorescence distribution and intensity of protoporphyrin Ⅸ in SW480 cells were observed under fluorescence microscope, the content of protoporphyrin Ⅸ in SW480 cells were quantitatively analyzed by high performance liquid chromatography. [Results] Different intensities of red fluorescence can be observed in SW480 from Group B and Group C. The fluorescence intensity of protoporphyrin Ⅸ from Group B is significantly higher than that from Group C. The count of high intensive fluorescence cells are respectively (57.67±2.49)% and (20.07±2.05)%, with significant difference (P 0.001); the content of protoporphyrin Ⅸin SW480 cells from 4 groups are different, Group A Group D Group C Group B. [Conclusion] It could efficiently increase cumulation of protoporphyrin IX in SW480 cells induced by DFO and 5-ALA.
Protoporphyrin IX
Group A
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Abstract δ‐Aminolevulinic acid (ALA)‐induced porphyrin accumulation is widely used in the treatment of cancer, as photodynamic therapy. To clarify the mechanisms of the tumor‐preferential accumulation of protoporphyrin, we examined the effect of the expression of heme‐biosynthetic and ‐degradative enzymes on the ALA‐induced accumulation of protoporphyrin as well as photodamage. The transient expression of heme‐biosynthetic enzymes in HeLa cells caused variations of the ALA‐induced accumulation of protoporphyrin. When ALA‐treated cells were exposed to white light, the extent of photodamage of the cells was dependent on the accumulation of protoporphyrin. The decrease of the accumulation of protoporphyrin was observed in the cells treated with inducers of heme oxygenase (HO)‐1. The ALA‐dependent accumulation of protoporphyrin was decreased in HeLa cells by transfection with HO‐1 and HO‐2 cDNA. Conversely, knockdown of HO‐1/‐2 with siRNAs enhanced the ALA‐induced protoporphyrin accumulation and photodamage. The ALA effect was decreased with HeLa cells expressing mitoferrin‐2, a mitochondrial iron transporter, whereas it was enhanced by the mitoferrin‐2 siRNA transfection. These results indicated that not only the production of porphyrin intermediates but also the reuse of iron from heme and mitochondrial iron utilization control the ALA‐induced accumulation of protoporphyrin in cancerous cells.
Protoporphyrin IX
HeLa
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ABSTRACT Cells of the ciliate Tetrahymena pyriformis GL overproduce and accumulate massive quantities of the heme intermediate, protoporphyrin IX. Protoporphyrin is localized intracellularly in discrete membranous compartments. The amount of porphyrin stored in the cell changes dramatically as cells progress through the growth cycle. Porphyrin overproduction is stimulated by δ‐aminolevulinic acid, but only during the mid‐stationary phase. Overproduction of protoporphyrin IX apparently results from an increase, late in the growth cycle, of activities subsequent to δ‐aminolevulinic acid synthetase. Feedback inhibition in the pathway by accumulated protoporphyrin IX does not occur. The presence of Co 2+ completely inhibits accumulation of protoporphyrin IX in a manner reversed by δ‐aminolevulinic acid. Sn 4+ stimulates protoporphyrin IX accumulation in the culture.
Protoporphyrin IX
Overproduction
Tetrahymena pyriformis
Hematoporphyrin
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Photodynamic effects of various types of porphyrins on cultured hepatocellular carcinoma cells (JTC-16) were studied, using an argon and dye laser. The porphyrins examined were hematoporphyrin derivative(HpD), hematoporphyrin, protoporphyrin, 31-hydroxyethyl-8-vinyldeuteroporphyrin (HVD) and 31-methoxyethyl-8-vinyldeuteroporphyrin (MVD). The photodynamic effects on the cells were evaluated by a phase contrast microscope at 24 hours after laser irradiation. An order of cell degeneration was obtained for protoporphyrin>MVD>HpD>HVD>hematoporphyrin.We conclude that photodynamic effects of porphyrins on the cultured cells would be due to photochemical response, since laser irradiation did not elevate the temperature of culture medium.
Hematoporphyrin
Protoporphyrin IX
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Objective To investigate the changes in levels of blood and tissue protoporphyrin IX in Sprague Dawley rats with colorectal carcinoma and normal Sprague Dawley rats.Methods Seventy Sprague Dawley rats were divided into two groups:experimental group ( n = 60) and control group ( n = 10). In experimental group,DMH (25 mg per kg) was injected into rat abdominal cavity once a week for 18 weeks.In control group,rats were not treated by DMH.At 20th week blood protoporphyrin IX in two groups and tissue protoporphyrin IX in experimental group were examined by fluorospectrophotometer.Results Blood protoporphyrin IX in experimental group and control group was (2.224± 0.323) mg/L, (1.663± 0.092) mg/L respectively.Blood protoporphyrin IX in experimental group was higher than that in control group ( P 0.01). Blood protoporphyrin IX/Hb in experimental group and control group was (25.908± 12.540) μg/g and 10.609± 0.929 μg/g respectively.Blood protoporphyrin IX/Hb in experimental group was higher than that in control group ( P 0.05). Protoporphyrin IX in normal tissue,early stage colorectal carcinoma and advanced colorectal carcinoma was (317.099± 16.859) ng/g, (416.814± 6.786) ng/g and (606.874± 21.798) ng/g respectively.The protoporphyrin IX in advanced colorectal carcinoma was higher than that in normal tissue,early stage colorectal carcinoma ( P 0.01). The protoporphyrin IX in early stage colorectal carcinoma was higher than that in normal tissue ( P 0.01). Conclusion Blood and tissue protoporphyrin IX levels are increased in colorectal carcinoma.Blood protoporphyrin IX may be used as a factor to screen colorectal carcinoma.
Protoporphyrin IX
Abdominal cavity
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Photodynamic effects of hematoporphyrin derivative(HpD), hematoporphyrin(Hp) and protoporphyrin (Pp) on cultured rat hepatocellular carcinoma cells (JTC-16), human hepatocellular carcinoma (HCC-1) and gastric cancer (GCA-1) serially transplanted in nude mice were studied, under the influence of a dye laser irradiation.The cell degeneration was observed most strongly in Pp, HpD and then Hp in order. The tumor degeneration of HCC-1 was observed most strongly in Hp and then HpD in order. On the other hand, the tumor degeneration of GCA-1 was observed most strongly in HpD and then Hp in order. Photodynamic effect of Pp was not observed in both GCA-1 and HCC-1.Therefore, it is suggested that Pp had the most powerful photodynamic effect on the cultured cells, but not on human cancer. This phenomenon would indicate that Pp has no affinity with the cancer tissue.
Hematoporphyrin
Protoporphyrin IX
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Of 18 compounds studied, only protoporphyrin significantly protected mice injected with lethal doses of “hematoporphyrin.” Results of separate experiments with 277 mice showed (a) 14% survival in 76 mice which received “Hp” and vehicle alone, (b) 47% survival in 90 mice injected with protoporphyrin in addition to the “Hp” and kept in the dark, and (c) 30% survival in 109 mice injected with both porphyrins and kept in a room illuminated with fluorescent lights. The marked fall in total body oxygen uptake associated with “Hp” administration was decreased considerably by administration of protoporphyrin.
Hematoporphyrin
Protoporphyrin IX
Ratón
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