Reinhard Hackenberg

Androgen receptor mediated growth control of breast cancer and endometrial cancer modulated by antiandrogen- and androgen-like steroids

Androgens are involved in many regulatory processes in mammary and endometrial epithelium, but their role in the development and progression of breast and endometrial carcinoma is poorly understood. Androgen receptors (AR) are found in normal epithelium as well as in more than 50% of specimen from both tumor types. The occurrence of AR is correlated with estrogen and progesterone receptors. Androgen receptor positive cell lines were established during the last few years in our laboratory from malignant mammary (MFM-223) and endometrial (MFE-296) tumors supplementing the small number of androgen-responsive cell lines published so far. In this paper some aspects of the role of androgens in these two types of hormone responsive female cancers are presented. The proliferation of ZR-75-1, MFM-223 and MFE-296 cells is inhibited by androgens. The progestin medroxyprogesterone acetate inhibits the proliferation of estrogen- and progesterone receptor negative MFM-223 cells via the androgen receptor. Some steroid metabolites with distinct estrogenic properties like androst-5-ene-3 beta,17 beta-diol possess androgenic properties in this model system. Androgens stimulate the in vitro secretion of gross cystic disease fluid proteins by human mammary cancer cells. These proteins are normally found in benign breast cysts in vivo. The occurrence of gross cystic disease is correlated with an increased risk of breast cancer. The AR is autoregulated in MFM-223 mammary cancer cells on the protein and mRNA level. In MFE-296 cells with endometrial origin AR protein was increased after incubation with androgens.

Medroxyprogesterone acetate inhibits the proliferation of estrogen- and progesterone-receptor negative MFM-223 human mammary cancer cells via the androgen receptor

SummaryThis study demonstrates for the first time, that medroxyprogesterone acetate (MPA) inhibits the proliferation of the estrogen and progesterone receptor negative mammary cancer cell line MFM-223 via the androgen receptor. MPA is a progestin, which is used in the hormonal treatment of disseminated breast cancer. It binds to the progesterone, androgen, and glucocorticoid receptor and may exert its antiproliferative effects via different receptors. MFM-223 human mammary cancer cells contain a very high level of androgen receptors (160 fmol/mg protein) and low levels of estrogen, progesterone, and glucocorticoid receptors (<20 fmol/mg protein). This cell line provides therefore a good model system to analyze the possible role of the androgen receptor in the action of MPA avoiding interference with other steroid hormone receptors. Effective inhibition of proliferation is achieved by 10 nM MPA or 1 nM of the androgen dihydrotestosterone, corresponding well to the binding affinities of both compounds (3.6 and 0.18 nM, respectively). The involvement of the androgen receptor was confirmed by competition experiments with antiandrogens. Furthermore, MFMDHT cells, which are an androgen resistant subline of MFM-223 cells, are also resistant to MPA. This data supports the involvement of the androgen receptor in the action of MPA and additionally rules out direct hormone-independent cytotoxic effects of MPA.

Estrogen and androgen receptor mediated stimulation and inhibition of proliferation by androst-5-ene-3β,17β-diol in human mammary cancer cells

Abstract Androst-5-ene-3β,17β-diol (ADIOL) and 5α-adrostane-3β,17β-diol (5αA), which are metabolites of dehydroepiandrosterone and dihydrotestosterone, are known to have estrogenic properties. This reevaluates the estrogenic effects of ADIOL and 5αA in MCF-7 cells and demonstrates additionally androgen-like inhibitory properties of these compounds in human hormone-dependent mammary cancer cells. ADIOL and 5αA (10–100 nM) stimulate the proliferation of estrogen-sensitive MCF-7 cells. Binding assays with the estrogen receptor and inhibition of stimulation with the antiestrogen tamoxifen support the involvement of the estrogen receptor. On the other hand, the mammary cancer cell line MFM-223 is strongly inhibited by ADIOL and 5αA in the same concentration range. This cell line is androgen receptor positive and is inhibited by androgens, but unresponsive to estrogens and progestins. The inhibitory effects of ADIOL and 5αA in MFM-223 cells are mediated by the androgen receptor as demonstrated by receptor studies and competition experiments with hormone antagonists. ADIOL and 5αA thus possess estrogen- and androgen-like properties and can stimulate or inhibit proliferation of human mammary cancer cells. The reactions of mammary cancer cells to these steroids depend on the receptor content and the growth properties of the individual cell line.

Stimulatory effects of androgen and antiandrogen on the in vitro proliferation of human mammary carcinoma cells

SummaryThe proliferation of three mammary carcinoma cell lines was explored for the effectiveness of dihydrotestosterone (DHT) and the antiandrogenic substances cyproterone acetate (CPA) or hydroxyflutamide. The cell growth, determined in multiple experimental cultures of the estrogen-sensitive lines MCF-7 and EFM-19, was stimulated by 10-9M to 10-6M DHT, whereas estrogen-resistant MFM-21 cells were unresponsive to the hormonal factors applied. Growth-promoting effects of 10-8M to 10-6M CPA were detected in cultures of those cell lines which were sensitive to estrogen and androgen. Competition experiments with DHT and the antiandrogens suggested involvement of the androgen receptor in the stimulation of cell growth by CPA. Participation of the estrogen receptor was excluded by lack of competition between CPA and the enhancement of proliferation by estradiol-17β. At the receptor level the anti-androgens were able to compete with androgen binding. The results of the study demonstrate androgenic properties of CPA in regard to the growth of human mammary carcinoma cells.

Regulation of androgen receptor mRNA and protein level by steroid hormones in human mammary cancer cells

The regulation of the human androgen receptor (AR) by steroid hormones in human mammary cancer cells was investigated using immunocytochemical and ligand binding assays for its protein and Northern blot analyses for the corresponding mRNA. MFM-223 cells contain high levels of ARs and are growth-inhibited by dihydrotestosterone (DHT). The AR protein is down-regulated to 57% of the control by 10 nM DHT after 24 h, and the corresponding mRNA is also reduced. The nonsteroidal antiandrogen hydroxyflutamide had no effect on the AR level, whereas after incubation with 1 microM cyproterone acetate a slight down-regulation was observed. The AR level was restored completely after release from a 7 day treatment with DHT. However, only 60% of the control level was restored, if the cells wer grown in the presence of DHT for 6 weeks. In androgen-pretreated cells the proliferation rate remained decreased even after the withdrawal of DHT. Concomitantly the distinct growth inhibition was lost. Transfection experiments demonstrated a reduced activity of the residual androgen receptor in these pretreated cells. In addition to the AR, EFM-19 cells also contain significant amounts of estrogen and progesterone receptors. EFM-19 cells are not growth inhibited by physiological concentrations of DHT. Autoregulation of AR was also found in this cell line. Additionally, reduced levels of AR protein and mRNA were found in EFM-19 cells after treatment with the synthetic progestin R5020. The maximum effect of R5020 was observed at the high concentration of 1 microM. Estrogen treatment with 10 nM 17 beta-estradiol for 3 days reduced the AR level only by 25%.

Down-regulation of androgen receptor by progestins and interference with estrogenic or androgenic stimulation of mammary carcinoma cell growth

SummaryThe regulatory influence of medroxyprogesterone acetate (MPA) on estrogen and androgen receptors of the human breast cancer cell lines MCF-7 and EFM-19 was explored in conjunction with the growth-promoting properties of these steroids. In the absence of steroidal stimulation, up to 1 μM MPA had no effect on the proliferation of the MCF-7 cell strain used and of EFM-19 cells. Under stimulation with 10 nM 17β-estradiol or 1 μM dihydrotestosterone, dose-dependent inhibition of the cell proliferation rates by 0.1–1 μM MPA was observed. Binding of MPA to the androgen receptor (Kd=2.1 nM) but not to the estrogen receptor was demonstrable. During incubation of MCF-7 or EFM-19 cells with 1 μM MPA for 7 days, the estrogen and androgen receptor contents were down-regulated by approximately 50% and 60%, respectively. Likewise, the number of androgen-binding sites was reduced to 35% of the untreated controls after incubation of MCF-7 cells with 1 μM synthetic progestin R5020 for 7 days. The results indicate down-regulation of estrogen and androgen receptors by progestins in the absence of stimulatory effects on the proliferation of mammary carcinoma cells.

Production of insulin-like growth factor binding proteins by human ovarian carcinoma cells.

Cells of the human ovarian carcinoma lines EFO-21, EFO-27, MFO-35 and MFO-36 secrete binding proteins for insulin-like growth factors (IGFBPs) into their culture media. By sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) and ligand blotting, seven groups of IGFBPs with molecular masses of 25, 30 (doublet), 34, 37, 40, 45, and 50 kDa were observed, depending on the cell line under investigation. By Northern blot analyses using cDNAs or oligonucleotides specific for the six types of IGFBP (IGFBP-1 to IGFBP-6), mRNA for all IGFBPs tested except for IGFBP-1 could be detected in the ovarian carcinoma cell extracts. In detail, analysis of EFO-21 protein products by SDS-PAGE yielded IGFBPs of 25, 34, and 50 kDa; extracts of EFO-21 cells contained mRNAs for IGFBP-2, -3, -4, and -6. EFO-27 cells produced IGFBPs of 40 kDa and 45 kDa as determined by SDS-PAGE, and mRNAs for IGFBP-3, -4, and -6 were detected. In the conditioned medium of MFO-35 cells, IGFBPs of 25, 30 (doublet), 34, 37, 40, and 45 kDa were observed by SDS-PAGE, while mRNAs for the five proteins IGFBP-2 to IGFBP-6 were found. MFO-36 cells produced IGFBPs of 34 kDa and 50 kDa as determined by SDS-PAGE, and the cells expressed mRNAs for IGFBP-2, -3, -4, and -6. In relation to published molecular mass data of the known IGFBPs, the size of the secreted proteins could be correlated to the mRNA patterns expressed by the ovarian carcinoma cells. It is concluded that ovarian carcinoma cells frequently express IGFBP-3, -4, and -6 and, to a lesser extent, IGFBP-2; the expression of IGFBP-5 appears as a rather rare event, while IGFBP-1 was not found to be expressed in ovarian carcinoma cells.

The response of uterine fibroids to GnRH-agonist treatment can be predicted in most cases after one month

Twenty-seven patients with uterine fibroids were treated for 3 months with the GnRH-agonist goserelin prior to surgical myomectomy. Ovarian function was suppressed reliably in all patients. After three applications, 15 fibroids were reduced in volume by more than 50%, and one complete remission was achieved. Seven patients showed a decrease of 10-50% in volume. However, in 5 cases there was no significant reduction. Analysing the time course of the fibroid reduction, the response can be predicted in most cases as early as four weeks after the first injection. Retrospective statistical analysis showed that a 50% reduction in fibroid size due to GnRH treatment is preceded by a 35% reduction after 4 weeks in 81% of cases, and after 8 weeks in all cases. Only 2 of 12 fibroids, which showed a smaller response (less than 50%) to GnRH therapy, were reduced by more than 35% after 4 and 8 weeks. In most cases it seems to be possible to estimate the individual response to GnRH-application after the first injection, so that it is possible to stop therapy in non-responding patients.

Establishment of new epithelial carcinoma cell lines by blocking monolayer formation

Abstract Human endometrial carcinoma cell lines were established by using a new cell culture technique. The malignant endometrial tumors were grossly disaggregated by mechanical means and cultivated in suspension culture. Adhesion to the bottom of the culture flasks was prevented by first coating the flasks with a thin agarose layer. Four cell lines were derived from 17 samples by this new technique. The cell lines obtained in this way were fully characterized, including karyotyping, intermediate filament staining and transplantation to nude mice. This new technique of initial suspension culture may also be applicable to other human tumors that are equally difficult to cultivate in vitro.

Das Endometriumkarzinom: Ein harmloser Tumor?

Noch vor wenigen Jahren wurde das Endometriumkarzinom als harmloser Tumor eingestuft, dessen Diagnose und Therapie im Vergleich zu Malignomen anderer primarer Organlokalisation unproblematisch erschien. Die bevorzugte Entstehung des Endometriumkarzinoms bei Frauen hoheren Lebensalters fuhrte zusatzlich zu einer Fehleinschatzung der gegenwartig erkannten Problematik. Unter Bezugnahme auf die verfugbaren Zahlen des Annual-Report hat sich wahrend der letzten Jahrzehnte eine enttauschend geringe Verbesserung der Heilungsergebnisse von etwa 10% herausgestellt. Dies wurde nicht durch eine Verbesserung der Therapie selbst, sondern lediglich durch eine bessere Nutzbarkeit langst etablierter Therapiemoglichkeiten erreicht. Diese Verdienste sind den modernen Entwicklungen in der Anasthesie und Intensivmedizin zuzuschreiben und nicht etwa Fortschritten in der onkologischen Forschung.