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S Sassa

Publications and source records attributed to S Sassa.

At least 73 records · Page 4Linked to original sources
PubMed1995

Expression of cytochrome P450 mRNAs in the colon and the rectum in normal human subjects.

The expression of mRNA for three isozymes of cytochrome P450, CYP1A1, 1A2 and 3A3, was examined in biopsied samples of colon and rectum from five healthy subjects. Using RT-PCR, it was possible to detect the three CYP mRNA species at both sites in all samples examined. The expression of each CYP mRNA was site-specific in that rectum had higher levels of CYP1A1 mRNA than colon, while colon had higher levels of CYP3A3 mRNA than in rectum. In contrast, there was no consistent trend in CYP1A2 mRNA expression between the two sites. Variability of alimentary CYP expression may contribute to individual differences in susceptibility to carcinogens and/or drugs.

Aged↗
PubMed1995

The effect of porphyrin and radiation on ferrochelatase and 5-aminolevulinic acid synthase in epidermal cells.

The effects of ultraviolet A (UVA) and blue light on ferrochelatase protein, and its mRNA level, in 5-aminolevulinic acid (ALA)-loaded A431 cells was evaluated. Western blot analysis of ferrochelatase protein showed a protein band of 43 kDa. There was a decrease in the protein concentration 24 h and 48 h after irradiation of these cells. In contrast, as judged by Northern blot analysis, there was no change in ferrochelatase mRNA level. Measurement of ALA synthase activity showed an ALA dose-dependent but radiation-independent decrease of enzyme activity, suggesting an end-product feedback inhibition. Since reactive oxygen species generated by porphyrin-induced photochemical reaction may be involved in the decrease in ferrochelatase protein, the effect of scavengers of reactive oxygen species was evaluated by measuring porphyrin accumulation in irradiated, ALA-loaded A431 cells. Porphyrin accumulation was significantly decreased in the presence of singlet oxygen scavenger sodium azide (0.05 mM, 40.6% suppression) or hydroxyl radical scavenger mannitol (5.0 mM, 45.0% suppression). These data suggest that the photochemical reaction induced by porphyrin and irradiation resulted in a decrease in ferrochelatase protein content, but had no effect on ferrochelatase mRNA level nor on ALA synthase activity. The decrease in protein was partly mediated by the reactive oxygen species.

5-Aminolevulinate Synthetase↗
PubMed1995

The effect of ALA and radiation on porphyrin/heme biosynthesis in endothelial cells.

To study porphyrin biosynthesis in human microvascular endothelial cells, HMEC-1 cells, a transformed human microvascular endothelial cell line, were incubated with 5-aminolevulinic acid (ALA), the precursor of endogenous porphyrins, and porphyrin accumulation was measured spectro-fluorometrically. The HMEC-1 cells accumulated porphyrin in a concentration-related and a time-dependent fashion. Protoporphyrin was the predominant porphyrin accumulated in the cells. The effect of light on protoporphyrin accumulation was evaluated by exposing the ALA-loaded HMEC-1 cells to ultraviolet-A (UVA) and blue light, followed by another incubation with ALA for 2-24 h. Enhancement of protoporphyrin accumulation in irradiated HMEC-1 cells was observed 2-24 h after irradiation, which was associated with a decrease in ferrochelatase protein and activity. Porphyrin accumulation from ALA after irradiation was significantly decreased when catalase (750-3000 U/mL, 29.3-44.3% suppression) or superoxide dismutase (270 U/mL, 36.4% suppression) was present during irradiation. These data demonstrate that HMEC-1 cells were capable of porphyrin biosynthesis, and that exposure of protoporphyrin-containing HMEC-1 cells to UVA and blue light, which includes the Soret band spectrum, decreased the ferrochelatase activity and its protein. These changes were mediated, at least in part, by reactive oxygen species.

Aminolevulinic Acid↗
PubMed1994

Suppression of cytochrome P450IA1 by interleukin-6 in human HepG2 hepatoma cells.

The effects of interleukin-6 (IL-6), the major inducer of the acute-phase reaction, on the expression of cytochrome P450IA1 (CYPIA1) were examined using human HepG2 hepatoma cells. Treatment of cells with IL-6 decreased the level of 3-methylcholanthrene-induced CYPIA1 protein and its mRNA. Nuclear runoff analysis revealed that the effect of IL-6 was largely transcriptional. IL-6 treatment of HepG2 cells increased mRNA for microsomal heme oxygenase, the rate-limiting enzyme in heme catabolism, suggesting that the suppressive effect of IL-6 on CYPIA1 mRNA may be due to a loss of heme. Consistent with this hypothesis, simultaneous treatment of cells with Sn-mesoporphyrin, an inhibitor of heme oxygenase, prevented the IL-6-mediated suppression of CYPIA1. These findings suggest that the suppression of P450IA1 mRNA by IL-6 appears to occur, at least in part, from the decline in free heme content as a result of the induction of heme oxygenase. Our results raise the possibility that other physiological as well as environmental stimuli which affect cellular heme concentrations may also modulate the expression of P450s.

Carcinoma, Hepatocellular↗
PubMed1994

[Long-term observation of serum hormone fluctuations in aging model of gonadectomized rat].

Serum LH increased rapidly in both sexes after gonadectomy, showing a peak at the 8th week. Afterwards, LH decreased gradually until the 75th week. In general, LH values in males were lower than those in females. FSH, as well as LH, increased rapidly after gonadectomy. In male serum FSH reached a peak at the 8th week and then decreased showing two peaks at the 34th and 92nd weeks. Serum FSH level decreased remarkably after the 96th week in males. In females FSH increased gradually with a subsequent rapid increase from the 28th week and reached a peak at the 42nd week. Afterwards, this FSH level was maintained to the 128th week. Serum progesterone (P4) decreased after gonadectomy in females, whereas it increased to 4 fold in males. In males this high level was maintained to the 66th week. Serum estradiol (E2) decreased in both sexes until the 3rd week after gonadectomy. However, in males the serum E2 level increased at the 4th and 5th weeks and reached the level of the 1st week after gonadectomy. Afterwards, the E2 level decreased to 10pg/ml at the 40th week which was maintained to the 128th week. In females, E2 increased from the 5th to 22nd week and decreased again from the 33rd week, and then the E2 level decreased rapidly to about 10pg/ml which was maintained to the 128th week. The present experiment indicated two results in male rats. 1. Serum FSH decreased remarkably after the 96th week of gonadectomy. 2. Serum P4 increased in spite of gonadectomy.

Aging↗
PubMed1994

Regulation of beta-globin mRNA accumulation by heme in dimethyl sulfoxide (DMSO)-sensitive and DMSO-resistant murine erythroleukemia cells.

The level of mRNA encoding beta-globin was examined in dimethyl sulfoxide (DMSO)-sensitive (DS), and DMSO-resistant (DR) murine erythroleukemia (MEL) cells. DR cells lack erythroid-specific delta-aminolevulinate (ALA) synthase (AL-AS-E), and fail to undergo erythroid differentiation following treatment with DMSO. Treatment of cells with DMSO markedly increased ALAS-E mRNA in DS cells, while the same treatment downregulated the nonspecific ALA synthase (ALAS-N) mRNA levels in both DS and DR cells. The levels of beta-globin mRNA, heme content, and hemoglobin in DS cells increased, while those in DR cells decreased following treatment with DMSO. Treatment of DR cells with hemin caused an increase in beta-globin mRNA and hemoglobin, and partially restored the DMSO-mediated suppression of beta-globin mRNA and hemoglobin synthesis. DMSO treatment decreased heme oxygenase (HO) mRNA in hemin-treated DS cells, but not in hemin-treated DR cells. These findings indicate that heme is necessary for accumulation of the beta-globin transcript during erythroid differentiation, and that hemin-mediated HO induction becomes markedly downregulated in differentiated erythroid cells, presumably because less free heme is available for HO induction by a greater demand for the synthesis of hemoglobin.

5-Aminolevulinate Synthetase↗
PubMed1994

Characterization and expression of cDNA encoding coproporphyrinogen oxidase from a patient with hereditary coproporphyria.

Hereditary coproporphyria (HCP) is an acute hepatic porphyria with autosomal dominant inheritance, but with a variable degree of clinical expression. Molecular cloning, sequencing and expression of the defective gene for coproporphyrinogen oxidase (CPO) in a patient with HCP were carried out. Enzyme assays revealed that CPO activity in EBV-transformed lymphoblastoid cells from the proband and one of her sisters was approximately 50% of normal. Nucleotide sequence analysis of CPO cDNAs isolated from the proband's cells demonstrated three base substitutions, and three accompanying amino acid substitutions. An A514-->C transition causing a Asn172-->His substitution occurred in one allele, while two other transitions, G265-->A and G580-->A, caused Gly89-->Ser and Val194-->Ile substitutions, respectively, in the other allele. The A514-->C and the G580-->A transitions are known genetic polymorphisms. Transfection of CPO cDNA into Escherichia coli demonstrated that cDNA with the G265-->A transition produced a protein with less than 5% of normal enzyme activity. These findings indicate that the G265-->A transition, involving the highly conserved glycine residue at the 89th position, is responsible for the CPO defect in the patient and accounts for the partial deficiency of CPO activity in this pedigree.

Amino Acid Sequence↗
PubMed1994

Changes with age of mammary glands in male and female soft-furred rat, Millardia meltada, in relation to prolactin and testosterone.

The soft-furred rat, millardia (Millardia meltada), is characterized by the development of androgen-dependent mammary tumours only in males. The age-related changes of the activities of thymidylate synthetase (TS) and thymidine kinase (TK), which contribute to DNA synthesis through de novo and salvage pathways, respectively, and structure in the mammary glands were studied in both males and females of this species between 5-28 months of age. While TK activity had no relation to age, TS activity decreased with age in males. In the females, TK activity increased with age, but not TS activity. These enzyme activities were generally higher in females than in males. The mammary glands of both sexes consisted of fine ducts with small end-buds and the glands of males contained mostly black pigments at any age examined. In either males or females, serum levels of prolactin and testosterone related little with age, DNA synthesizing enzyme activities or structure of the mammary glands. Furthermore, elevation by pituitary grafting of circulating prolactin affected neither DNA synthesizing enzyme activities nor structure of mammary glands in both sexes. The histological structures of adrenal, testis, ovary, ventral prostate and uterus of millardia were essentially similar to those of mice or rats.

Adrenal Glands↗
PubMed1993

Establishment and characterization of an erythropoietin-dependent subline, UT-7/Epo, derived from human leukemia cell line, UT-7.

UT-7 is a human leukemic cell line capable of growing in interleukin-3 (IL-3), granulocyte/macrophage colony-stimulating factor (GM-CSF), or erythropoietin (Epo) (Komatsu et al, Cancer Res 51:341, 1991). To study the effect of Epo on proliferation and differentiation of UT-7, we maintained the UT-7 cell culture for more than 6 months in the presence of Epo. As a result, a subline, UT-7/Epo, was established. The growth of UT-7/Epo could be supported by Epo but not by GM-CSF or IL-3. UT-7/Epo showed a greater level of heme content and ratio of benzidine-positive staining cells than did UT-7. Butyric acid promoted the synthesis of hemoglobin in UT-7/Epo, but not UT-7. Further, the mRNA concentrations of the c-myb oncogene and GM-CSF receptor beta-subunit were decreased substantially in UT-7/Epo cells. These findings showed that UT-7/Epo cells had progressed further in erythroid development than UT-7 cells, and suggested that long-term culture in Epo had promoted this differentiation. Whereas availability of the Epo receptor (Epo-R) for binding of Epo was reduced in UT-7/Epo cells compared with UT-7 cells, the Epo-R showed a similar affinity for Epo. This observation suggested that change(s) in postreceptor signaling step might be involved in the establishment and maintenance of the UT-7/Epo phenotype.

Butyrates↗
PubMed1993

Effect of interleukin-11 on the levels of mRNAs encoding heme oxygenase and haptoglobin in human HepG2 hepatoma cells.

Effect of recombinant human interleukin-11 (rhIL-11) on the expression of transcripts encoding microsomal heme oxygenase (HO), the rate-limiting enzyme in heme catabolism, and haptoglobin (Hpt), a major acute-phase protein, were examined in human HepG2 hepatoma cells. Treatment of HepG2 cells with rhIL-11 elicited an increase in HO mRNA in a dose- and a time-dependent fashion. The dose response curve, its magnitude of response and its time course were similar to those observed with recombinant human interleukin-6 (rhIL-6). In contrast, rhIL-11 had a far smaller effect on the level of Hpt mRNA than did rhIL-6. These findings demonstrate that the two cytokines are similar in regulating heme catabolism, while markedly different in inducing certain acute-phase proteins.

Gene Expression↗
PubMed1993

The role of inorganic metals and metalloporphyrins in the induction of haem oxygenase and heat-shock protein 70 in human hepatoma cells.

The role of inorganic metals and metalloporphyrins in the induction of mRNAs for haem oxygenase and heat-shock protein 70 (hsp70), the two heat-shock proteins, was examined in human HepG2 and Hep3B hepatoma cells. SnCl2, but not Sn-protoporphyrin, was found to be a potent inducer of both haem oxygenase and hsp70 mRNAs. In contrast, CoCl2, ZnCl2 and FeCl2 caused little induction of haem oxygenase and hsp70 mRNAs, whereas the porphyrin complexes of these metals strongly induced haem oxygenase mRNA, without influencing the level of hsp70 mRNA. The induction process was largely transcriptional, as judged by the inhibition of induction by actinomycin D, but not by cycloheximide, and by increased transcription demonstrated by nuclear run-off analysis. Since CoCl2 is a potent inducer of haem oxygenase in vivo in animals, the possibility of the biosynthesis of Co-protoporphyrin was examined in human hepatoma cells by incubating them with CoCl2 and protoporphyrin, or delta-aminolaevulinate (ALA), the precursor of protoporphyrin. Both types of treatment led to a potent induction of haem oxygenase mRNA. Co-protoporphyrin formation was also spectrally demonstrated in cells incubated with the metal and ALA. The results of this study indicate that certain metals, e.g. SnCl2, may directly induce haem oxygenase mRNA, whereas with other elements, incorporation of the metal into the porphyrin macrocycle is necessary for induction. Therefore CoCl2, like haemin, may activate the haem oxygenase gene via a haem-responsive transcription factor, whereas SnCl2 may exert its effect via a metal-responsive transcription factor.

Carcinoma, Hepatocellular↗
PubMed1993

Effects of danazol on DNA synthesis in rat prostate.

Effects of danazol, an isoxazol derivative of the synthetic steroid 17 alpha-ethinyltestosterone, on activities of thymidylate synthetase and thymidine kinase, which are the DNA-synthesizing enzymes included in de novo and salvage pathways of pyrimidine metabolism, respectively, were investigated in rat prostate. Danazol markedly reduced plasma levels of luteinizing hormone and testosterone, and organ weight, both enzyme activities and bromodeoxyuridine-immunoreactive cells which were regarded as the S-phase cells in prostate. These results indicate that danazol shows a property as a potent antigonadotropin.

Animals↗
PubMed1993

Effects of danazol on endometrial DNA synthesis in rats.

The suppressive effects of Danazol, an isoxazol derivative of the synthetic steroid 17 alpha-ethinyltestosterone, on endometrial DNA synthesis were investigated in rats by immunohistochemistry with bromodeoxyuridine (BrdU) and DNA-synthesizing enzyme assays. Rats treated with Danazol for 14 days at 17-19 weeks of age showed a decrease of plasma gonadotropins associated with ovarian hypofunction, persistent diestrus, and a smaller number of corpora lutea in ovary, resulting in no BrdU-immunoreactive (S-phase) cells in endometrial epithelium and lower activity of thymidine kinase in the uterus compared with control.

Adrenal Glands↗
PubMed1993

Haem is necessary for a continued increase in ferrochelatase mRNA in murine erythroleukaemia cells during erythroid differentiation.

The level of mRNA encoding ferrochelatase (FeC) was examined in two murine erythroleukaemia (MEL) clones, DS and DR, a DMSO-sensitive, and a DMSO-resistant clone, respectively. DS cells undergo erythroid differentiation by DMSO treatment with a marked increase in haem synthesis, while DR cells fail to do so due to the lack of the erythroid-specific delta-aminolaevulinate synthase (ALAS-E). Both DS and DR cells showed an increase in the level of FeC mRNA within 18 h of DMSO treatment. The level of FeC mRNA in DR cells was then decreased, while that in DS cells continued to increase for 72 h. Treatment with haemin significantly increased FeC mRNA in DR cells. When cells were treated with both DMSO and haemin, the level of FeC mRNA in DR cells increased to a level comparable to that in DS cells. These findings suggest that the failure to maintain increased FeC mRNA DR cells after DMSO treatment may be due to a deficiency of haem in these cells.

Animals↗
PubMed1993

Dimethyl sulphoxide and haemin induce ferrochelatase mRNA by different mechanisms in murine erythroleukaemia cells.

The level of mRNA encoding ferrochelatase (FeC), the terminal enzyme of the haem biosynthetic pathway, was examined in murine erythroleukaemia (MEL) cells when they were induced to undergo erythroid cell differentiation by treatment with dimethyl sulphoxide (DMSO), or haemin. FeC mRNA increased within 12 h after DMSO or haemin treatment of MEL cells, and its level continued to increase for 48 h. Treatment of cells with succinylacetone (SA), a potent inhibitor of haem synthesis, suppressed a DMSO-mediated increase in FeC mRNA, and haemin treatment reversed a SA-mediated decrease in FeC mRNA. Nuclear runoff analyses showed that, while DMSO increased the rate of transcription of FeC mRNA, haemin did not. These results indicate that the induction of FeC mRNA by DMSO is largely transcriptional, while that by haemin is post-transcriptional.

Animals↗
PubMed1993

Effect of UVA and blue light on porphyrin biosynthesis in epidermal cells.

To study porphyrin biosynthesis in normal human keratinocytes and A431 cells derived from human epidermoid carcinoma, cultured cells were incubated with delta-aminolevulinic acid (ALA), the precursor of porphyrin synthesis, and accumulation of porphyrins was measured spectrofluorometrically. Both human keratinocytes and A431 cells accumulated porphyrins in a time-dependent and a dose-dependent fashion. Protoporphyrin was the predominant porphyrin accumulated by both cell types. Porphyrin accumulation was enhanced by Ca Mg ethylenediaminetetraacetic acid, a ferrochelatase inhibitor, and the enhancement was reversed by the addition of iron, suggesting the utilization of iron by ferrochelatase. The effect of light on porphyrin accumulation was evaluated by exposing the ALA-loaded A431 cells to ultraviolet-A (UVA) and blue light radiation, followed by continued incubation with ALA for 2-48 h. There was an enhancement of porphyrin accumulation 2-48 h after the radiation as compared with nonirradiated controls. Consistent with this finding, ferrochelatase activity decreased in these cells at 24 h and 48 h. These data demonstrate that human keratinocytes and A431 cells are capable of porphyrin biosynthesis, and that exposure of porphyrin-containing A431 cells to light, which includes the Soret band spectrum, decreases the ferrochelatase activity, which is responsible, at least in part, for the further increase in porphyrin level.

Calcium↗
PubMed1993

Porphyrin synthesis by murine epidermal cells.

Incubation of murine epidermal cells with delta-aminolevulinic acid (ALA) resulted in a dose- and time-dependent accumulation of porphyrins, predominantly of protoporphyrin. Porphyrin accumulation decreased in the presence of iron, and the iron-mediated decrease was partially reversed by CaMg EDTA (1.25-10.0 mM), suggesting that there is functionally active ferrochelatase in these cells. This study suggests that these cells may be a useful model for the study of cutaneous porphyrin metabolism involving ferrochelatase activity.

Aminolevulinic Acid↗