| 21. |
- 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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| 22. |
- Dabrosin, Charlotta
(författare)
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Effects of sex steroids on normal human breast : studies in vivo using microdialysis and in vitro in cell culture
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Prolonged exposure to sex steroids may constitute a risk factor for the development of breast cancer. The biological mechanisms involved in breast carcinogenesis are not well understood.Basic knowledge of sex steroid effects on the normal human breast is still limited, one reason being the lack of an available in vivo technique for investigations of breast tissue metabolism.In this study, the microdialysis technique was developed and evaluated as a method for measurements of tissue-specific concentrations of amino acids, lactate, pyruvate and glutathione in normal human breast tissue during the menstrual cycle. The technique was successfully applied to breast tissue and it was observed that the concentrations of several amino acids as well as glutathione changed during the menstrual cycle. Oxidative damage to cells is one of the mechanisms which may be involved in the development of breast cancer. Normal aerobic metabolism generates potentially dangerous oxidants which are controlled by a variety of antioxidant systems. The exact regulatory mechanisms of these systems are not yet fully understood. We studied the effects of estradiol and progesterone on antioxidative activity in normal human breast tissue, in vivo with the microdialysis technique, and in vitro using normal human breast epithelial cells in culture. The in vivo levels of the antioxidant glutathione were measured early and late in the menstrual cycle in breast tissue and subcutaneous fat. The glutathione levels were higher late in the menstrual cycle in both tissues, when the serum levels of estradiol and progesterone were high. In vitro, breast epithelium exposed to estradiol and progesterone exhibited decreased activity of the antioxidative enzymes catalase and glutathione reductase, whereas the activity of glutathione peroxidase tended to increase compared with cells grown in medium without added sex hormones. The vulnerability to oxidative stress, induced by hydrogen peroxide, increased in cells grown with estradiol and progesterone present in the media. α-Tocopherol, and α-tocopherol in combination with ascorbic acid, but not ascorbic acid alone, protected from cell death induced by hydrogen peroxide. This effect was not dependent on estradiol and progesterone exposure.In conclusion, the data suggest an effect of estradiol and progesterone on antioxidative activity in normal human breast tissue both in vivo and in vitro.Microdialysis will be a useful tool in future research of these and other aspects concerning human breast tissue.
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| 23. |
- 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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| 24. |
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| 25. |
- 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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| 26. |
- Dabrosin, Charlotta, 1961-
(författare)
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Increased extracellular local levels of estradiol in normal breast in vivo during the luteal phase of the menstrual cycle
- 2005
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Ingår i: Journal of Endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 187:1, s. 103-108
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Tidskriftsartikel (refereegranskat)abstract
- Estrogen exposure is a major risk factor for breast cancer. Tissue estrogen originates from the ovaries but a significant portion is also produced by enzyme activity locally in the breast itself. How these enzymes are regulated is not fully understood. The extracellular space, where the metabolic exchange and cell interactions take place, reflects the environment that surrounds the epithelium but there has been no previous study of hormone concentrations in this compartment. In the present study microdialysis was used to measure extracellular estrogen concentrations in breast tissue and abdominal subcutaneous fat in 12 healthy women in vivo. It was found that women with high plasma progesterone levels had significant increased levels of estradiol in breast tissue compared with fat tissue (breast tissue 168 ± 6 pM, subcutaneous fat, 154 ± 5 pM, P<0.05), whereas women with low plasma progesterone exhibited no difference. Moreover, there was a significant correlation between local breast tissue estradiol and plasma progesterone levels (r=0.709, P<0.01). There was no difference in estrone sulphate in breast and fat tissue regardless of progesterone levels. Estrone was not detectable. The results in this study suggest that progesterone may be one regulator in the local conversion of estrogen precursors into potent estradiol in normal breast tissue. © 2005 Society for Endocrinology.
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| 27. |
- 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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| 28. |
- Dabrosin, Charlotta, 1961-
(författare)
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Positive correlation between estradiol and vascular endothelial growth factor but not fibroblast growth factor-2 in normal human breast tissue in vivo
- 2005
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Ingår i: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 11:22, s. 8036-8041
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Angiogenesis is crucial in tumor development and progression. Ovarian hormones regulate angiogenesis in the reproductive tract but very little is known about its regulation in the normal breast. Sex steroids play an important role in breast cancer development by poorly understood mechanisms. Vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) are potent stimulators of angiogenesis. Both VEGF and FGF-2 function in autocrine/ paracrine pathways and there is a major contribution of bioactive proteins by a posttranslational activation of sequestered molecules in the extracellular space. A direct measurement of these molecules in the extracellular compartment is, therefore, needed. Experimental Design: In this study, microdialysis was used to measure extracellular VEGF and FGF-2 in normal human breast tissue in situ in 11 premenopausal and 5 postmenopausal women. Results: Significantly higher level of VEGF in breast tissue of premenopausal women was found. Plasma as well as local estradiol and breast tissue VEGF exhibited significant correlations, whereas progesterone had no correlation with breast VEGF. FGF-2 did not correlate with either estradiol or progesterone. Conclusion: The result suggests that estradiol is a more potent regulator of free VEGF levels than progesterone in the normal breast. The control of free FGF-2 seems to be independent of sex steroids in the breast. Estrogen induction of free extracellular VEGF may be one mechanism involved in sex steroid - dependent breast carcinogenesis. © 2005 American Association for Cancer Research.
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| 29. |
- Dabrosin, Charlotta, 1961-
(författare)
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Sex steroid regulation of angiogenesis in breast tissue
- 2005
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Ingår i: Angiogenesis. - : Springer Science and Business Media LLC. - 0969-6970 .- 1573-7209. ; 8:2, s. 127-136
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Tidskriftsartikel (refereegranskat)abstract
- Angiogenesis is essential for normal function in the female reproductive tract and a prerequisite for growth and metastasis of solid tumors. Several factors, both inducers and inhibitors, play essential roles in the regulation of the angiogenic process. Exposure to sex steroids increases the risk of breast cancer but the mechanisms are poorly understood and the importance of angiogenesis in breast carcinogenesis is undefined. In the female reproductive tract ovarian hormones tightly regulate angiogenesis. The breast is also a target organ for sex steroids but very little is known about sex steroid effects on angiogenesis in normal breast tissue and breast cancer. In this review several regulators of angiogenesis, and their relation to sex steroids, in breast tissue are discussed. Increased knowledge in this area is of utmost importance for future therapeutic treatment options and for breast cancer prevention. © Springer 2005.
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| 30. |
- 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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