Thomas Rabe

Testosterone and 5α-dihydrotestosterone inhibit in vitro growth of human breast cancer cell lines

Androgens are of biological and clinical importance for the growth and development of breast cancer in women, and the androgen receptor (AR) has been shown to be a predictor of tumor differentiation. In the present study, we investigated the relationship between AR status and testosterone and 5α-dihydrotestosterone (DHT)-dependent proliferation of the human breast carcinoma cell lines MCF-7, T47-D, MDA-MB 435S and BT-20. AR status was studied by means of immunocytochemistry and Western blot analysis. All four cell lines stained positively for AR. Western blot analysis revealed a strong expression of AR in MCF-7, in contrast to BT-20 cells. According to proliferation kinetics, we observed a significant (p ≤ 0.05) dose-dependent inhibition of cell growth by testosterone and DHT treatment in all four cell lines. In the estrogen receptor (ER)-negative cell lines BT-20 and MDA-MB 435S, testosterone was a more potent inhibitor of cell proliferation than DHT (p ≤ 0.05), in contrast to the ER-positive cells lines MCF-7 and T47-D, in which a stronger inhibition of proliferation was achieved by DHT. A partial transformation of testosterone to estrogen in ER-positive cells might be an explanation for this effect. Our data favor a possible role of androgens in growth regulation of breast cancer. Clinical studies are needed to analyze the importance of AR as a possible predictor in response to endocrine therapy of breast cancer.

Gonadotropin releasing hormone enhances polyphosphoinositide hydrolysis in rat pituitary cells

Addition of gonadotropin releasing hormone to myo-[2-3H]inositol-prelabeled rat pituitary cells in primary culture evoked a dose-dependent increase of the accumulation of [3H]inositol phosphates with a rise of inositol triphosphate within 30 sec of stimulation, followed by a rise in inositol diphosphate and inositol monophosphate. Inositol phosphate accumulation was enhanced up to 5-to-8-fold and was time-dependent between up to 15 min incubation without further increase beyond this time period. Without preincubation with LiCl2, there was no measurable increase of GnRH-induced inositol phosphate accumulation compared to controls. The presence of calcium in the incubation medium did not affect the increase of inositol phosphates. These data give evidence, that polyphosphoinositide breakdown may be an early step in the action of gonadotropin releasing hormone on gonadotropin secretion.

New progestogens in oral contraceptives

The aim of using new synthetic progestogens (gestodene and norgestimate) in oral hormonal contraceptives is to find a combination that has a more beneficial effect on metabolism and endometrium than presently available formulations. Our studies with low-dose pills containing 30 µLg ethinyl estradiol/150 µg levonorgestrel or 30 µg ethinyl estradiol/150 µg desogestrel compared with the new pills with 35 µg ethinyl estradiol/250 µg norgestimate or 30 µg ethinyl estradiol/75 µg gestodene revealed no significant alterations of serum glucose after glucose loading. With all four combination pills, insulin levels were slightly elevated when compared with controls. Studies of the lipid metabolism showed that depending on the type and estrogen combination, progestogens have different effects on lipid metabolism. The new progestogens seem to have a more pronounced effect on triglycerides, whereas total cholesterol and high-density lipoprotein cholesterol remain almost unchanged. In general, it could be shown that low-dose oral contraceptives have little impact on lipid metabolism. Studies with low-dose monophasic preparations, including the new formulations, reveal only a low effect on blood coagulation. According to our and other data on the new progestogens in oral contraceptives available so far, it can be expected that such low-dose monophasic and triphasic combination pills will be beneficial during longtime use with respect to side effects on the cardiovascular system and control of the menstrual cycle.

S2k-Leitlinie zur Therapie der Akne

To optimize the treatment of acne in Germany, the German Society of Dermatology (DDG) and the Association of German Dermatologists (BVDD) initiated a project to develop consensus-based guidelines for the management of acne. The Acne Guidelines focus on induction therapy, maintenance therapy and treatment of post-acne scarring. They include an evaluation of the most commonly used therapeutic options in Germany. In addition, they offer detailed information on how to administer the various treatments and on contraindications, adverse drug reactions, and drug interactions, taking into account gender and special conditions such as pregnancy and lactation. The Acne Guidelines were developed following the recommendations of the Association of Scientific Medical Societies in Germany (AWMF). The treatment recommendations were developed by an expert group and finalized by an interdisciplinary consensus conference. The first choice treatments for acute acne according to acne type are as follows: 1) comedonal acne: topical retinoids; 2) mild papular/pustular acne: fixed or sequential combinations of BPO and topical retinoids or of BPO and topical antibiotics; 3) moderate papular/pustular acne: oral antibiotic plus BPO or plus topical retinoid, or in a fixed combination 4) acne papulo-pustulosa nodosa and acne conglobata: oral antibiotic plus topical retinoid plus BPO or oral isotretinoin. For maintenance treatment: topical retinoid or its combination with BPO. Particular attention should be paid to compliance and quality of life. Additional treatment options are discussed in the main body of the text.

The efficacy and tolerability of norgestimate/ethinyl estradiol (250 μg of norgestimate/35 μg of ethinyl estradiol): Results of an open, multicenter study of 59,701 women

The efficacy and tolerability of a new oral contraceptive, norgestimate/ethinyl estradiol (250 μg of norgestimate/35 μg of ethinyl estradiol; Cilag GmbH Research, Sulzbach, Germany) were examined in an open-label study of 59,701 women who were evaluated during 342,348 menstrual cycles; 42,022 women completed the planned treatment regimen of six cycles. A use-efficacy (overall) Pearl index of 0.25 pregnancies per 100 woman-years was calculated based on 342,348 cycles. Tolerability was assessed for all women who completed six treatment cycles. Reductions in mean cycle length and duration of bleeding were noted; 32% of the women experienced reductions in the intensity of bleeding by the end of cycle 6. After six cycles of use, amenorrhea occurred in 1%, spotting in 4%, and breakthrough bleeding in 3% of the participating women. Treatment with norgestimate/ethinyl estradiol had minimal effects on weight, blood pressure, pulse, lipid metabolism, and blood glucose. Adverse effects (acne, nausea, or headaches) occurred at low frequencies and in many cases, were reduced compared with pretreatment levels. The results of this large-scale open trial were comparable with results from two other multicenter trials of the same formulation.

Stimulation of luteinizing hormone release by melittin and phospholipase A2 in rat pituitary cells

Gonadotropin release in rat pituitary monolayer cultures was stimulated by phospholipase A2, as well as by its activator melittin. A dose-dependent stimulation of luteinizing hormone secretion by melittin was observed in a dose range of 10(-8) to 10(-4) M. A higher dose (1 mM) melittin had a sub-optimal effect. The stimulatory action of melittin was calcium-dependent and blocked by phospholipase A2 inhibitors, chloroquine and quinacrine. Similar to melittin, phospholipase A2 enhanced the effect of LH release in a dose range of 0.1-100 units/ml. The effect of this enzyme was also calcium-dependent with optimal calcium concentrations at 1.5 mM, as obtained also for melittin. In superfusion experiments, the stimulatory action of melittin and phospholipase A2 was reproducible in their effects on LH release in gonadotrophs. In addition, melittin (10(-7) M) stimulated LH and 3H-arachidonic acid efflux in superfused pituicytes following prelabelling with radiolabelled arachidonate. These data suggest that phospholipase A2, which releases arachidonic acid from phospholipids, may participate in controlling gonadotropin secretion in gonadotrophs, since arachidonic acid and its metabolites have previously been found to enhance gonadotropin release.

Stimulation of gonadotropin release by arachidonic acid and its lipoxygenase metabolites in superfused pituitary cells

Luteinizing hormone and follicle stimulating hormone secretion was stimulated by 4 min pulses of arachidonic acid (3 X 10(-5) to 10(-4)M) in superfused rat pituitary cells. The effect of its lipoxygenase metabolites, 5-hydroxy-6,8,11,14-eicosatetranoic acid (5-HETE) and 15-hydroxy-5,8,10,14-eicosatetranoic acid (15-HETE) was more potent on hormone release when added in the same dose. Using 3 X 10(-5)M 5-HETE, its releasing activity on gonadotropins was comparable to that of GnRH (10(-9)M). 15-HETE (3 X 10(-5)M) was even more potent on LH and FSH secretion than 5-HETE. The secretory profile induced by 5-HETE and 15-HETE was also similar to that shown for GnRH, resulting in a rapid increase and a more prolonged decline of the hormone release. The addition of these fatty acids to superfused pituitary cells did not alter the response of the cells to their physiological ligand. These findings give further support to the proposal that metabolites of arachidonic acid may be involved in receptor-mediated mechanisms of gonadotropin release in pituitary cells.

INFLUENCE OF ETHANOL ON IN VITRO GROWTH OF HUMAN MAMMARY CARCINOMA CELL LINE MCF-7

We have shown that ethanol in concentrations of 0,0001%-10% significantly enhances 3H-thymidine uptake in cultured human mammary carcinoma cell line MCF-7. Methanol only enhances 3H-thymidine uptake in a concentration of 0,01%.

Induction of estrogen receptor-α and -β activities by synthetic progestins

The cellular action of steroid hormones is mediated by specific receptors. Recently, two different estrogen receptors (ER), α and β, have been cloned with a specific tissue distribution. Active estrogen as well as active progestin are compounds of oral hormonal contraceptives and hormone replacement therapy. To examinate the regulation of ER-α and -β activities after treatment with synthetic progestins and synthetic and natural estrogens, COS 7 cells were transfected with the vector expressing ER-α and -β in combination with a luciferase reporter vector. ER-α activity was upregulated in the presence of synthetic progestins in a dose-dependent manner. Norethisterone, norethynodrel and desogestrel proved to be the most potent stimulatory agents of ER-α expression. On the other hand, not all progestins exhibited a stimulatory action on ER-β activity. Only norgestrel, levonorgestrel, norethynodrel and norethisterone induced ER-β-activating functions in a dose-dependent manner. Luciferase activity due to estrogen stimulation served as a positive control. Our results indicate that progestins have different effects on the activities of ER-α and -β.

Leukotrienes stimulate gonadotropin release in vitro

Monolayer cell cultures of female rat anterior pituitaries were used to investigate the effect of leukotrienes (LT) LTA4, LTB4, LTC4, LTD4, LTE4 and other lipoxygenase metabolites of arachidonic acid (5-HETE, 5-HPETE, and 15-HETE) in vitro. 3H-arachidonic acid was rapidly incorporated into pituicytes and its release was enhanced by gonadotropin releasing hormone (GnRH) in superfused pituitary cells. Leukotrienes were found to be very potent stimulators of the release of luteinizing hormone (LH) when added as pulses to superfused pituicytes. At equimolar concentrations, LTA4, LTB4, LTC4 and LTE4 were found to be more potent than the physiological stimulus GnRH. LTD4 did not affect gonadotropin secretion. Other lipoxygenase metabolites of arachidonic acid, such as 5-HETE, 5-HPETE and 15-HETE were less effective on the exocytosis of LH. These results suggest that leukotrienes are potential mediators of GnRH action on gonadotropin secretion and are possible sites of regulation of pituitary function.