| 401. |
- Nilsson, Ulrika, et al.
(författare)
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Tamoxifen and Flaxseed Alter Angiogenesis Regulators in Normal Human Breast Tissue In Vivo
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 6:9
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Tidskriftsartikel (refereegranskat)abstract
- The incidence of breast cancer is increasing in the Western world and there is an urgent need for studies of the mechanisms of sex steroids in order to develop novel preventive strategies. Diet modifications may be among the means for breast cancer prevention. Angiogenesis, key in tumor progression, is regulated by the balance between pro-and anti-angiogenic factors, which are controlled in the extracellular space. Sampling of these molecules at their bioactive compartment is therefore needed. The aims of this study were to explore if tamoxifen, one of the most used anti-estrogen treatments for breast cancer affected some of the most important endogenous angiogenesis regulators, vascular endothelial growth factor (VEGF), angiogenin, and endostatin in normal breast tissue in vivo and if a diet supplementation with flaxseed had similar effects as tamoxifen in the breast. Microdialysis was used for in situ sampling of extracellular proteins in normal breast tissue of women before and after six weeks of tamoxifen treatment or before and after addition of 25 g/day of ground flaxseed to the diet or in control women. We show significant correlations between estradiol and levels of VEGF, angiogenin, and endostatin in vivo, which was verified in ex vivo breast tissue culture. Moreover, tamoxifen decreased the levels of VEGF and angiogenin in the breast whereas endostatin increased significantly. Flaxseed did not alter VEGF or angiogenin levels but similar to tamoxifen the levels of endostatin increased significantly. We conclude that one of the mechanisms of tamoxifen in normal breast tissue include tipping of the angiogenic balance into an anti-angiogenic state and that flaxseed has limited effects on the pro-angiogenic factors whereas the anti-angiogenic endostatin may be modified by diet. Further studies of diet modifications for breast cancer prevention are warranted.
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| 402. |
- Nilsson, Ulrika, et al.
(författare)
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Tamoxifen decreases extracellular TGF-beta 1 secreted from breast cancer cells - A post-translational regulation involving matrix metalloproteinase activity
- 2009
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 315:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor-beta 1 (TGF-beta 1) promotes cancer progression by regulating tumor cell growth and angiogenesis and high levels of TGF-beta 1 have been associated with metastatic disease and poor prognosis in breast cancer patients. We have previously reported anti-angiogenic effects of the anti-estrogen tamoxifen in breast cancer, by increased matrix metalloproteinase-9 (MMP-9) activity and generation of endostatin. Here, we show that exposure of tamoxifen to ER-positive breast cancer cells for 7 days, decreased extracellular TGF-beta 1. Intracellular TGF-beta 1 levels were unaffected by tamoxifen treatment, indicating a post-translational regulation of TGF-beta 1. Inhibition of MMP activity restored TGF-beta 1 levels, suggesting an involvement of MMP activities in the down-regulation of TGF-beta 1 by tamoxifen. Moreover, using an in vivo model of solid MCF-7 tumors in nude mice, we analyzed tumor levels of TGF-beta 1 after in vivo treatment with estradiol and tamoxifen. Exposure of tumor-bearing mice to tamoxifen significantly decreased tumor TGF-beta 1 protein levels, tumor growth and angiogenesis. In conclusion, our findings suggest a novel mechanism of action of tamoxifen in breast cancer via sex steroid dependent modulation of the proteolytic tumor microenvironment resulting in reduced extracellular TGF-beta 1 levels.
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| 403. |
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| 404. |
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| 405. |
- Nilsson, Ulrika
(författare)
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Under huden
- 2005
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Ingår i: Kroppen. - : Nationalmuseum, Stockholm.
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Bokkapitel (populärvet., debatt m.m.)
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| 406. |
- Nilsson, Ulrika
(författare)
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Under huden
- 2005
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Ingår i: Kroppen. - : Nationalmuseum, Stockholm.
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Bokkapitel (populärvet., debatt m.m.)
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| 407. |
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| 408. |
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| 409. |
- Nilsson, Ulrika W., 1977-
(författare)
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Effects of sex steroids and tamoxifen on matrix metalloproteinase activity and generation of endostatin in the breast
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sex steroids are inevitable in women. However, long-term exposure to sex steroids increases the risk of breast cancer. A complete understanding of sex steroid control of the breast and how it relates to breast cancer risk is still lacking. Angiogenesis and proteolytic enzyme activity are crucial for the process by which tumors evolve into a vascularized, invasive phenotype. Matrix metalloproteinases are potent matrixdegrading enzymes that affect several steps in tumor progression including angiogenesis. In the female reproductive organs, sex steroids regulate angiogenesis and MMP activity, yet little is known how sex steroids affect these crucial events in normal and malignant breast tissue.This thesis elucidates a link between sex steroids, MMP activity, and angiogenesis. It is shown that estradiol down-regulates while tamoxifen up-regulates the protein expression and activity of MMP-2 and MMP-9 in human breast cancer cells in vitro and in human breast cancer xenografts in vivo. The results further suggest that a biological consequence of this regulation may be modulation of tumor angiogenesis. The net effect of adding tamoxifen to estradiol treatment was an increase in extracellular levels of the endogenous angiogenesis inhibitor endostatin and decreased levels of the tumor promoter TGF-β1 compared to estradiol treatment only. This was accompanied by reduced vasculature and decreased tumor growth. Similarly, a regulatory effect of estradiol and tamoxifen on endostatin generation was observed in normal human breast tissue by whole-tissue culture and microdialysis in human breast tissue in situ.In conclusion, the results presented in this thesis suggest previously unknown mechanisms of action of estradiol and tamoxifen in breast cancer and in normal human breast tissue, and novel means by which estradiol may tip the scale to favor angiogenesis. This knowledge may be important for the understanding of sex steroid dependent breast carcinogenesis and in the future development of tissue-specific preventive as well as therapeutic strategies against breast cancer.
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| 410. |
- Nilsson, Ulrika W., et al.
(författare)
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Estradiol and tamoxifen regulate endostatin generation via matrix metalloproteinase activity in breast cancer in vivo
- 2006
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Ingår i: Cancer Research. - 0008-5472 .- 1538-7445. ; 66:9, s. 4789-4794
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Tidskriftsartikel (refereegranskat)abstract
- Matrix metalloproteinases (MMP) are important regulators of tumor progression and angiogenesis. MMPs generate both proangiogenic and antiangiogenic fragments, such as vascular endothelial growth factor and endostatin. The in vivo activation of MMPs and endostatin generation occur mainly in the extracellular environment by interactions of different cell types. Therefore, these processes are necessary to study in the extracellular space in vivo. Sex steroids play a dominant role in breast carcinogenesis, by largely unknown mechanisms. In the present study, we used in vivo microdialysis to directly quantify MMP-2 and MMP-9 activity and sample endostatin from both stroma (murine) and tumor (human) cells in vivo in solid MCF-7 tumors in nude mice. We found that tamoxifen in combination with estradiol increased tumor MMP-2/MMP-9 in vivo activity, endostatin levels, and decreased tumor vascularization compared with estradiol treatment only. The stroma-derived endostatin was three to five times higher than cancer cell–generated endostatin. After inhibition of MMP-2/MMP-9, endostatin levels decreased, providing evidence that these proteases are highly involved in the generation of endostatin. Our results support the previously reported concept that MMPs may serve as negative regulators of angiogenesis. The regulation of endostatin generation by modulation of MMP-2/MMP-9 activities suggests a previously unrecognized mechanism of estradiol and tamoxifen, which may have implications for the pathogenesis of breast cancer.
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