| 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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Estradiol increases extracellular levels of vascular endothelial growth factor in vivo in murine mammary cancer
- 2003
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 107:4, s. 535-540
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Tidskriftsartikel (refereegranskat)abstract
- Angiogenesis is essential for tumor growth and metastasis and an important prognostic factor in breast cancer. VEGF, a key factor for angiogenesis, has been correlated with tumor vessel density in breast cancer. Estrogen, another crucial factor in breast cancer, stimulates VEGF, and an ERE in the VEGF gene has been defined. VEGF is bioactive in the extracellular fluid, where it becomes available to endothelial cells. Whether E2 affects VEGF levels in the extracellular fluid is not known. We show, using intratumoral microdialysis in vivo, that E2 treatment increased tumor extracellular levels of VEGF in an estrogen-dependent breast cancer model. Moreover, extracellular levels of VEGF in the tumor showed a strong correlation with total tumor VEGF, contrary to plasma levels of VEGF. Ninety-three percent of measured VEGF in the extracellular fluid in the tumor was tumor-derived, while only 45% of VEGF in circularing plasma originated from the tumor. We conclude that E2 increases extracellular VEGF and that microdialysis is a sensitive method for measurement of local VEGF production in vivo. Our results have potential application to the assessment of tumor characteristics in vivo in human tumors for individualized cancer therapy.
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| 3. |
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| 4. |
- Dabrosin, Charlotta, 1961-
(författare)
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Increase of free insulin-like growth factor-1 in normal human breast in vivo late in the menstrual cycle
- 2003
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Ingår i: Breast Cancer Research and Treatment. - 0167-6806 .- 1573-7217. ; 80:2, s. 193-198
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Tidskriftsartikel (refereegranskat)abstract
- Prolonged exposure to endogenous and exogenous sex steroids increases the risk of breast cancer but the mechanisms are poorly understood. Increased levels of circulating insulin-like growth factor-1 (IGF-1) and low levels of IGF binding protein are associated with increased risk of breast cancer suggesting that IGF-1 has to be in its free form to be biologically active. Little is known about sex steroid regulation of IGF-1 locally in the breast. In this study microdialysis was used to determine the local levels of free IGF-1 in normal human breast tissue in healthy female volunteers during the menstrual cycle. The results showed that the extracellular levels of free IGF-1 locally in the breast were doubled in the luteal phase, when estradiol and progesterone levels were elevated, compared with the follicular phase. In plasma, free IGF-1 levels also exhibited a cyclic variation but to a less extent. The increased local levels of the tree form of IGF-1 may promote proliferation in the breast epithelium. This could be important in sex steroid dependent breast cancer development.
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| 5. |
- Dabrosin, Charlotta, 1961-, et al.
(författare)
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Oestradiol enhances tumour regression induced by B7-I/IL-2 adenoviral gene transfer in a murine model of breast cancer
- 2003
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 89:2, s. 385-390
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Tidskriftsartikel (refereegranskat)abstract
- The majority of breast cancers are oestrogen dependent and although current treatment strategies have improved, approximately 50% of the patients will develop metastasis. New treatments that result in long-term systemic immunity are therefore being developed. We have previously shown that adenoviral gene transfer of B7-I/IL-2 to murine breast cancer induces a high rate of complete turnout regression and systemic immunity. Since oestrogens not only affect breast cancer but also have been shown to modulate immune function and secretion of immune-regulatory cytokines, we explored whether administration of oestradiol altered the immune response induced by an adenoviral vector expressing B7-I/IL-2. An oestrogen-dependent murine breast cancer tumour was used in ovariectomised mice, supplemented either oestradiol or placebo. We report the somewhat unexpected finding that intratumoral injection of adenovirus expressing B7-I/IL-2 induces complete turnout regression in 76% of oestradiol-supplemented mice, while only 18% of the tumours regressed in the oestrogen-depleted group. Cured mice in both groups exhibited a similar CTL response against the tumour antigen. However, intratumoral IFN-? levels, 2 days after B7-I/IL-2 injection, were significantly higher in mice treated with oestradiol compared to placebo. This may be one mechanism explaining the higher response rate of tumours in oestradiol-replenished mice.
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| 6. |
- Dabrosin, Charlotta, 1961-
(författare)
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Technical aspects of microdialysis of human breast
- 2001
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 61:4, s. 269-272
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Tidskriftsartikel (refereegranskat)abstract
- In this study a technique for insertion of microdialysis catheters and the influence of the position of the catheters within normal human breast tissue were evaluated by measuring amino acids. Moreover, to assess variability over time, the levels of amino acids were measured during a period of 3 h. In nine healthy women two parallel microdialysis catheters were implanted, guided by a catheter for intravenous use, into the breast tissue. All insertions were successful and there were no complications. The levels of amino acids were equal in the two parallel catheters and varied less than 10% over a period of 3 h. Insertion of the microdialysis catheter via an intravenous catheter is suitable for the dense breast tissue. The position of the microdialysis catheter within the same breast seems to be of minor importance for measurements of amino acids. Thus, the described technique is a safe and reproducible way of investigating the human breast in vivo.
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| 7. |
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| 8. |
- 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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| 9. |
- Dabrosin, Charlotta
(författare)
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Variability of vascular endothelial growth factor in normal human breast tissue in vivo during the menstrual cycle
- 2003
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 88:6, s. 2695-2698
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to sex steroids increases the risk of breast cancer, but the mechanisms are poorly understood. Angiogenesis is crucial in tumor development and progression. Very little is known about the regulation of angiogenesis in the normal breast. Vascular endothelial growth factor ( VEGF) has a key stimulatory role in angiogenesis. Interferon-inducible protein 10 (IP-10) is a potent inhibitor of angiogenesis in vivo. These factors function in autocrine/paracrine pathways, therefore, direct measurements in the target tissue are needed. I measured VEGF and IP-10 in normal human breast tissue in situ in healthy women, using microdialysis, in the follicular and luteal phase of the menstrual cycle. In breast tissue, VEGF levels increased in the luteal phase, compared with the follicular phase (17.8+/-4 pg/ml to 34+/-9 pg/ml, P<0.05). Plasma VEGF did not show a cyclic variation (10.6&PLUSMN,2.8 pg/ml vs. 14.6&PLUSMN,3.5 pg/liter, P=0.3). IP-10 levels did not vary during the menstrual cycle either in breast tissue (65&PLUSMN,17 pg/ml vs. 75&PLUSMN,21 pg/ml, P=0.6) or in plasma (64&PLUSMN,7 pg/ml vs. 81&PLUSMN,10 pg/ml, P=0.06). The data suggests that, in the luteal phase, VEGF and IP-10, in the normal human breast, exhibit a proangiogenic profile. This may be one mechanism by which sex steroids contribute to breast cancer development.
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| 10. |
- Garvin, Stina, et al.
(författare)
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Tamoxifen inhibits secretion of vascular endothelial growth factor in breast cancer in vivo
- 2003
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Ingår i: Cancer research. - 0008-5472. ; 63, s. 8742-8748
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Tidskriftsartikel (refereegranskat)abstract
- Vascular endothelial growth factor (VEGF) is considered a key mediator of tumor angiogenesis, including neovascularization in human breast cancer. High tissue VEGF levels appear to correlate with poor prognosis and decreased overall survival in node-positive and node-negative breast cancer patients. Hormonal regulation of VEGF expression has been demonstrated, and some reports indicate that tamoxifen, a partial estrogen receptor agonist, increases VEGF mRNA in breast cancer cells. These results appear to contradict the efficacy of tamoxifen as an adjuvant for estrogen-dependent breast cancer, yet clinical data show that tamoxifen prevents metastasis and increases overall survival. In this study, we confirmed previous studies showing that intracellular levels of VEGF in vitro increased in response to tamoxifen to levels similar to those observed after estrogen treatment. To further study hormonal effects on the release of VEGF, we used microdialysis to sample the extracellular space, where VEGF is biologically active, in solid tumors in situ. We show for the first time that tamoxifen decreased extracellular VEGF in vivo in solid MCF-7 tumors in nude mice. These in vivo findings were confirmed in vitro where extracellular VEGF in the cell culture medium was decreased significantly by tamoxifen treatment. Furthermore, we illustrate that microdialysis is a viable method that may be applied in human breast tissue to detect soluble VEGF in situ released by the tumor.
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