Dagfinn Ekse

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Previous studies have suggested elevated estrogen production in tumour-bearing breast quadrants as well as in breast cancers versus benign tissue. Using highly sensitive assays, we determined breast cancer tissue estrogen concentrations together with plasma and benign tissue estrogen concentrations in each quadrant obtained from mastectomy specimens (34(More)
A major obstacle to the understanding of the mechanisms of action of aromatase inhibitors in breast cancer is the observation that plasma estrogens are sustained at about 30-50% of their control levels despite 85-95% inhibition of the conversion of tracer androstenedione (A) to estrone (E1). The discrepancy could be due to lack of sensitivity of current(More)
Following the introduction of potent aromatase inhibitors for the treatment of breast cancer patients, highly sensitive methods have become mandatory to evaluate the influence of these drugs on plasma estrogen levels. Commercially available kits for estrogen measurements are not suitable for these kinds of evaluations due to their detection limits that are(More)
Aromatase inhibition is a well-defined treatment option for postmenopausal breast cancer. Although several aromatase inhibitors such as aminoglutethimide, formestane and fadrozole have been found to inhibit in vivo aromatization by >85%, previous studies reported plasma estrogen levels to be sustained at approximately 20-50% of their control level during(More)
BACKGROUND The cytochrome P450 (CYP) enzymes 2C19, 2D6, and 3A5 are responsible for converting the selective estrogen receptor modulator (SERM), tamoxifen to its active metabolites 4-hydroxy-tamoxifen (4OHtam) and 4-hydroxy-N-demethyltamoxifen (4OHNDtam, endoxifen). Inter-individual variations of the activity of these enzymes due to polymorphisms may be(More)
Plasma insulin-like growth factor (IGF)-I, free IGF-I and -II, IGF-binding protein (IGFBP)-1, -2, and -3 together with IGFBP-3 protease activity were measured in 114 postmenopausal and 39 premenopausal healthy women. For each parameter, the mathematical distribution was characterised, and the normal range for pre- and postmenopausal women described,(More)
The adipocytokine leptin has recently been shown to enhance the expression of aromatase via promoter II and I.3 using an AP-1 motif. Thus, we evaluated the correlation between plasma leptin concentrations and total body aromatization (TBA) as well as plasma levels of estrone (E(1)), estradiol (E(2)) and estrone sulfate (E(1)S) in postmenopausal breast(More)
Estrone sulphate (E1S) may be an important estrogen source in breast cancers, particularly in postmenopausal women. Recent studies have shown that tamoxifen inhibits the uptake and metabolism of E1S to estradiol (E2) in cell cultures. To evaluate a possible influence of tamoxifen on E1S disposition in vivo, we measured plasma levels of E1S together with(More)
The aromatase inhibitor aminoglutethimide (AG) is widely used in the treatment of advanced breast cancer in postmenopausal women. Apart from the inhibition of estrogen synthesis, previous studies by our group have shown that AG selectively enhances plasma clearance of the estrogen conjugate estrone sulphate (E1S). In the present study we used a novel,(More)
Droloxifene (3-hydroxytamoxifen) is a novel antiestrogen currently undergoing clinical investigations for treatment of breast cancer patients. We measured plasma levels of sex hormone binding globulin (SHBG) and the gonadotrophins (LH and FSH) at baseline and after 3 months on treatment in a group of fourteen postmenopausal women treated with droloxifene 40(More)