| 1. |
- Dabrosin, Charlotta, 1961-, et al.
(författare)
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Decreased secretion of Cathepsin D in breast cancer in vivo by tamoxifen : Mediated by the mannose-6-phosphate/IGF-II receptor?
- 2004
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Ingår i: Breast Cancer Research and Treatment. - 0167-6806 .- 1573-7217. ; 85:3, s. 229-238
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Tidskriftsartikel (refereegranskat)abstract
- The lysosomal protease Catliepsin D (Cath D) is associated with increased invasiveness and metastasis in breast cancer. Both estrogen and tamoxifen have been reported to increase Cath D, which seems to contradict the efficacy of tamoxifen as an adjuvant for estrogen dependent breast cancer. Cath D is bioactive in the extracellular space but very little is known about hormonal regulation of secreted Cath D in vivo. In this study we used microdialysis to sample the extracellular fluid in estrogen receptor positive MCF-7 tumors in nude mice. We show that tamoxifen in combination with estradiol decreased secreted Cath D compared with estradiol treatment only in solid tumors in situ. Cell culture of MCF-7 cells revealed that estradiol and tamoxifen increased intracellular proteolytic activity of Cath D in a similar fashion whereas secretion of Cath D was increased by estradiol and inhibited by tamoxifen. Immunofluorescence showed that estradiol located Cath D to the cell surface, while tamoxifen accumulated Cath D to dense lysosomes in perinuclear regions. Moreover, tamoxifen increased the intracellular transporter of Cath D, the mannose 6-phosphate/IGF-II receptor (M6P/IGF2R). In contrast, estradiol decreased the levels of this receptor. Thus, secretion of Cath D is hormone dependent and may be mediated by altered expression of the M6P/IGF2R. Our results highlight the importance of measurements of proteins in all compartments where they are biological active and show that microdialysis is a viable technique for sampling of Cath D in vivo.
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| 2. |
- Dabrosin, Charlotta, 1961-, et al.
(författare)
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Variability of glutathione during the menstrual cycle - Due to estrogen effects on hepatocytes?
- 2004
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Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 36:2, s. 145-151
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Tidskriftsartikel (refereegranskat)abstract
- Oxidative stress and alterations in the antioxidative defense system may be involved in carcinogenesis. We have previously shown that the levels of glutathione (GSH) in vivo in both breast tissue and subcutaneous fat were higher in the luteal phase compared with the follicular phase, suggesting an overall increase in GSH. This result was confirmed in the present study. Moreover, we exposed normal breast tissue in vivo, breast epithelial cells in vitro, and hepatocytes in culture to ovarian hormones. We found that local perfusion with estradiol, using microdialysis, in normal human breast tissue did not alter the local GSH levels in vivo. In vitro, treatment with estradiol and progesterone of normal human breast epithelial cells did not alter GSH levels. However, levels of GSH in hepatocytes were after 8 h estradiol exposure initially decreased, 76.6 ± 5% of control cells, p < .05, whereas 20 h exposure more than doubled GSH, 209 ± 26% compared with control cells, p < .01. Progesterone had no additional effect. Exposure of hepatocytes to estradiol increased the cellular content of γ-glutamylcysteine synthetase, the rate-limiting enzyme in GSH synthesis. In conclusion we suggest that estradiol affects the GSH homeostasis mainly by effects on hepatocytes, whereas local production in the breast is unaffected by estradiol.
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| 3. |
- Schöier, Johan, et al.
(författare)
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Chlamydia trachomatis -induced apoptosis occurs in uninfected McCoy cells late in the developmental cycle and is regulated by the intracellular redox state
- 2001
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Ingår i: Microbial Pathogenesis. - : Elsevier BV. - 0882-4010 .- 1096-1208. ; 31:4, s. 173-184
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Tidskriftsartikel (refereegranskat)abstract
- Infections with the obligate intracellular bacterium Chlamydia trachomatis are characterized by avoidance of fusion between chlamydia-containing endosomes and lysosomes, bacterial persistence and development of post-infectious sequelae. In this report we show that C. trachomatis induces apoptosis in McCoy and HeLa cells. Apoptosis was monitored by three different techniques; enzyme-linked immunoassay (EIA) of fragmented nucleosomes, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) and flow cytometry of propidium iodide-stained cells. Apoptosis occurred in uninfected cells, was induced late in the chlamydial developmental cycle, beyond 24 h post-infection and was dependent on bacterial protein synthesis. Apoptosis was not significantly increased in infected, inclusion-containing cells. Treatment of cells with the antioxidants ascorbic acid (10 μM) and α-tocopherol (10 μM) reduced the degree of apoptosis. These results suggest that host cells infected with C. trachomatis generate proapoptotic stimuli that induce apoptosis in uninfected, neighbouring cells and that the redox state of the cell is a regulator in chlamydia-induced apoptosis.
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| 4. |
- Terman, Alexei, 1957-, et al.
(författare)
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Decreased apoptotic response of inclusion-cell disease fibroblasts : A consequence of lysosomal enzyme missorting?
- 2002
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 274:1
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Tidskriftsartikel (refereegranskat)abstract
- To better understand the role of lysosomes in apoptosis, we compared the responses to apoptotic stimuli of normal fibroblasts with those of inclusion cells (I-cells), i.e., fibroblasts with impaired function of lysosomal enzymes due to their missorting and ensuing nonlysosomal localization. Although both cell types did undergo apoptosis when exposed to the lysosomotropic detergent MSDH, the redox-cycling quinone naphthazarin, or the protein kinase inhibitor staurosporine, I-cells exerted a markedly decreased response to these agonists than did normal fibroblasts. Furthermore, leupeptin and pepstatin A (inhibitors of cysteine and aspartic proteases, respectively) suppressed staurosporine-induced apoptosis of normal fibroblasts, whereas survival of I-cells was unaffected. These findings give further support for the involvement of lysosomal enzymes in apoptosis and suggest I-cells as a suitable model for studying the role of lysosomes in programmed cell death.
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| 5. |
- Öllinger, Karin, 1962-, et al.
(författare)
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Induction of apoptosis by redoxcycling quinones
- 2002
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Ingår i: Phospholipid metabolism in apoptosis. - Linköping : Linköpings universitet. - 0306467828 - 9780306479311 ; , s. 151-170
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The last few years have witnessed an explosion of both interest and knowledge about apoptosis, the process by which a cell actively commits suicide. It is now well recognised that apoptosis is essential in many aspects of normal development and is required for maintaining tissue homeostasis. The molecular mechanisms of apoptosis are presently unknown and the subject of focused research effort. It is clear that cell membrane structure and properties play an early part in the induction process. There is increasing evidence that the arrangement of polar lipids in the membrane lipid matrix is an important factor coupled with the homeostatic mechanisms responsible for preserving membrane lipid composition and asymmetry. Changes in membrane permeability are also likely to be involved, possibly as a direct consequence of disturbances in the lipid bilayer matrix. The purpose of this volume is to examine the involvement of membrane lipids in early events of apoptosis. In particular, the role of phospholipids in mitochondrial permeability, membrane lipid asymmetry, and sphingolipid and phospholipid signalling processes in early apoptotic events are reviewed by current researchers in these fields
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| 6. |
- Öllinger, Karin, 1962-
(författare)
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Inhibition of cathepsin D prevents free-radical-induced apoptosis in rat cardiomyocytes
- 2000
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861 .- 1096-0384. ; 373:2, s. 346-351
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Tidskriftsartikel (refereegranskat)abstract
- Apoptosis was inhibited in rat cardiomyocytes pretreated with the aspartic protease inhibitor pepstatin A and subsequently exposed to naphthazarin (5,8-dihydroxy-1,4-naphthoquinone). Cathepsin D was released from lysosomes to the cytosol upon exposure to naphthazarin, and the enzyme activity decreased simultaneously. Later, cathepsin D reappeared in granules of increased size, and enzyme activity was restored. Activation of caspase-3- like proteases was detected, and the number of cells showing apoptotic morphology increased with time. Pepstatin A pretreatment did not prevent release of cathepsin D from lysosomes but did significantly inhibit subsequent naphthazarin-induced caspase activation and apoptotic morphology. This suggests that cathepsin D exerts its apoptosis-stimulating effect upstream of caspase-3-like activation. (C) 2000 Academic Press.
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